source: downloads/tcl8.5.2/generic/tclCompCmds.c @ 35

/*
 * tclCompCmds.c --
 *
 *      This file contains compilation procedures that compile various Tcl
 *      commands into a sequence of instructions ("bytecodes").
 *
 * Copyright (c) 1997-1998 Sun Microsystems, Inc.
 * Copyright (c) 2001 by Kevin B. Kenny.  All rights reserved.
 * Copyright (c) 2002 ActiveState Corporation.
 * Copyright (c) 2004-2006 by Donal K. Fellows.
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclCompCmds.c,v 1.143 2008/03/16 17:00:43 dkf Exp $
 */

#include "tclInt.h"
#include "tclCompile.h"

/*
 * Macro that encapsulates an efficiency trick that avoids a function call for
 * the simplest of compiles. The ANSI C "prototype" for this macro is:
 *
 * static void          CompileWord(CompileEnv *envPtr, Tcl_Token *tokenPtr,
 *                          Tcl_Interp *interp, int word);
 */

#define CompileWord(envPtr, tokenPtr, interp, word) \
    if ((tokenPtr)->type == TCL_TOKEN_SIMPLE_WORD) { \
        TclEmitPush(TclRegisterNewLiteral((envPtr), (tokenPtr)[1].start, \
                (tokenPtr)[1].size), (envPtr)); \
    } else { \
        envPtr->line = mapPtr->loc[eclIndex].line[word]; \
        TclCompileTokens((interp), (tokenPtr)+1, (tokenPtr)->numComponents, \
                (envPtr)); \
    }

/*
 * TIP #280: Remember the per-word line information of the current command. An
 * index is used instead of a pointer as recursive compilation may reallocate,
 * i.e. move, the array. This is also the reason to save the nuloc now, it may
 * change during the course of the function.
 *
 * Macro to encapsulate the variable definition and setup.
 */

#define DefineLineInformation \
    ExtCmdLoc *mapPtr = envPtr->extCmdMapPtr; \
    int eclIndex = mapPtr->nuloc - 1

/*
 * Convenience macro for use when compiling bodies of commands. The ANSI C
 * "prototype" for this macro is:
 *
 * static void          CompileBody(CompileEnv *envPtr, Tcl_Token *tokenPtr,
 *                          Tcl_Interp *interp);
 */

#define CompileBody(envPtr, tokenPtr, interp) \
    TclCompileCmdWord((interp), (tokenPtr)+1, (tokenPtr)->numComponents, \
            (envPtr))

/*
 * Convenience macro for use when compiling tokens to be pushed. The ANSI C
 * "prototype" for this macro is:
 *
 * static void          CompileTokens(CompileEnv *envPtr, Tcl_Token *tokenPtr,
 *                          Tcl_Interp *interp);
 */

#define CompileTokens(envPtr, tokenPtr, interp) \
    TclCompileTokens((interp), (tokenPtr)+1, (tokenPtr)->numComponents, \
            (envPtr));
/*
 * Convenience macro for use when pushing literals. The ANSI C "prototype" for
 * this macro is:
 *
 * static void          PushLiteral(CompileEnv *envPtr,
 *                          const char *string, int length);
 */

#define PushLiteral(envPtr, string, length) \
    TclEmitPush(TclRegisterNewLiteral((envPtr), (string), (length)), (envPtr))

/*
 * Macro to advance to the next token; it is more mnemonic than the address
 * arithmetic that it replaces. The ANSI C "prototype" for this macro is:
 *
 * static Tcl_Token *   TokenAfter(Tcl_Token *tokenPtr);
 */

#define TokenAfter(tokenPtr) \
    ((tokenPtr) + ((tokenPtr)->numComponents + 1))

/*
 * Macro to get the offset to the next instruction to be issued. The ANSI C
 * "prototype" for this macro is:
 *
 * static int   CurrentOffset(CompileEnv *envPtr);
 */

#define CurrentOffset(envPtr) \
    ((envPtr)->codeNext - (envPtr)->codeStart)

/*
 * Note: the exceptDepth is a bit of a misnomer: TEBC only needs the
 * maximal depth of nested CATCH ranges in order to alloc runtime
 * memory. These macros should compute precisely that? OTOH, the nesting depth
 * of LOOP ranges is an interesting datum for debugging purposes, and that is
 * what we compute now.
 *
 * static int   DeclareExceptionRange(CompileEnv *envPtr, int type);
 * static int   ExceptionRangeStarts(CompileEnv *envPtr, int index);
 * static void  ExceptionRangeEnds(CompileEnv *envPtr, int index);
 * static void  ExceptionRangeTarget(CompileEnv *envPtr, int index, LABEL);
 */

#define DeclareExceptionRange(envPtr, type) \
    (TclCreateExceptRange((type), (envPtr)))
#define ExceptionRangeStarts(envPtr, index) \
    (((envPtr)->exceptDepth++), \
    ((envPtr)->maxExceptDepth = \
            TclMax((envPtr)->exceptDepth, (envPtr)->maxExceptDepth)), \
    ((envPtr)->exceptArrayPtr[(index)].codeOffset = CurrentOffset(envPtr)))
#define ExceptionRangeEnds(envPtr, index) \
    (((envPtr)->exceptDepth--), \
    ((envPtr)->exceptArrayPtr[(index)].numCodeBytes = \
        CurrentOffset(envPtr) - (envPtr)->exceptArrayPtr[(index)].codeOffset))
#define ExceptionRangeTarget(envPtr, index, targetType) \
    ((envPtr)->exceptArrayPtr[(index)].targetType = CurrentOffset(envPtr))

/*
 * Prototypes for procedures defined later in this file:
 */

static ClientData       DupDictUpdateInfo(ClientData clientData);
static void             FreeDictUpdateInfo(ClientData clientData);
static void             PrintDictUpdateInfo(ClientData clientData,
                            Tcl_Obj *appendObj, ByteCode *codePtr,
                            unsigned int pcOffset);
static ClientData       DupForeachInfo(ClientData clientData);
static void             FreeForeachInfo(ClientData clientData);
static void             PrintForeachInfo(ClientData clientData,
                            Tcl_Obj *appendObj, ByteCode *codePtr,
                            unsigned int pcOffset);
static ClientData       DupJumptableInfo(ClientData clientData);
static void             FreeJumptableInfo(ClientData clientData);
static void             PrintJumptableInfo(ClientData clientData,
                            Tcl_Obj *appendObj, ByteCode *codePtr,
                            unsigned int pcOffset);
static int              PushVarName(Tcl_Interp *interp,
                            Tcl_Token *varTokenPtr, CompileEnv *envPtr,
                            int flags, int *localIndexPtr,
                            int *simpleVarNamePtr, int *isScalarPtr, int line);
static int              CompileAssociativeBinaryOpCmd(Tcl_Interp *interp,
                            Tcl_Parse *parsePtr, const char *identity,
                            int instruction, CompileEnv *envPtr);
static int              CompileComparisonOpCmd(Tcl_Interp *interp,
                            Tcl_Parse *parsePtr, int instruction,
                            CompileEnv *envPtr);
static int              CompileStrictlyBinaryOpCmd(Tcl_Interp *interp,
                            Tcl_Parse *parsePtr, int instruction,
                            CompileEnv *envPtr);
static int              CompileUnaryOpCmd(Tcl_Interp *interp,
                            Tcl_Parse *parsePtr, int instruction,
                            CompileEnv *envPtr);
static void             CompileReturnInternal(CompileEnv *envPtr,
                            unsigned char op, int code, int level,
                            Tcl_Obj *returnOpts);

/*
 * Flags bits used by PushVarName.
 */

#define TCL_CREATE_VAR     1    /* Create a compiled local if none is found */
#define TCL_NO_LARGE_INDEX 2    /* Do not return localIndex value > 255 */

/*
 * The structures below define the AuxData types defined in this file.
 */

AuxDataType tclForeachInfoType = {
    "ForeachInfo",              /* name */
    DupForeachInfo,             /* dupProc */
    FreeForeachInfo,            /* freeProc */
    PrintForeachInfo            /* printProc */
};

AuxDataType tclJumptableInfoType = {
    "JumptableInfo",            /* name */
    DupJumptableInfo,           /* dupProc */
    FreeJumptableInfo,          /* freeProc */
    PrintJumptableInfo          /* printProc */
};

AuxDataType tclDictUpdateInfoType = {
    "DictUpdateInfo",           /* name */
    DupDictUpdateInfo,          /* dupProc */
    FreeDictUpdateInfo,         /* freeProc */
    PrintDictUpdateInfo         /* printProc */
};

/*
 *----------------------------------------------------------------------
 *
 * TclCompileAppendCmd --
 *
 *      Procedure called to compile the "append" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "append" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileAppendCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *varTokenPtr, *valueTokenPtr;
    int simpleVarName, isScalar, localIndex, numWords;
    DefineLineInformation;      /* TIP #280 */

    numWords = parsePtr->numWords;
    if (numWords == 1) {
        return TCL_ERROR;
    } else if (numWords == 2) {
        /*
         * append varName == set varName
         */

        return TclCompileSetCmd(interp, parsePtr, cmdPtr, envPtr);
    } else if (numWords > 3) {
        /*
         * APPEND instructions currently only handle one value.
         */

        return TCL_ERROR;
    }

    /*
     * Decide if we can use a frame slot for the var/array name or if we need
     * to emit code to compute and push the name at runtime. We use a frame
     * slot (entry in the array of local vars) if we are compiling a procedure
     * body and if the name is simple text that does not include namespace
     * qualifiers.
     */

    varTokenPtr = TokenAfter(parsePtr->tokenPtr);

    PushVarName(interp, varTokenPtr, envPtr, TCL_CREATE_VAR,
                &localIndex, &simpleVarName, &isScalar,
                mapPtr->loc[eclIndex].line[1]);

    /*
     * We are doing an assignment, otherwise TclCompileSetCmd was called, so
     * push the new value. This will need to be extended to push a value for
     * each argument.
     */

    if (numWords > 2) {
        valueTokenPtr = TokenAfter(varTokenPtr);
        CompileWord(envPtr, valueTokenPtr, interp, 2);
    }

    /*
     * Emit instructions to set/get the variable.
     */

    if (simpleVarName) {
        if (isScalar) {
            if (localIndex < 0) {
                TclEmitOpcode(INST_APPEND_STK, envPtr);
            } else if (localIndex <= 255) {
                TclEmitInstInt1(INST_APPEND_SCALAR1, localIndex, envPtr);
            } else {
                TclEmitInstInt4(INST_APPEND_SCALAR4, localIndex, envPtr);
            }
        } else {
            if (localIndex < 0) {
                TclEmitOpcode(INST_APPEND_ARRAY_STK, envPtr);
            } else if (localIndex <= 255) {
                TclEmitInstInt1(INST_APPEND_ARRAY1, localIndex, envPtr);
            } else {
                TclEmitInstInt4(INST_APPEND_ARRAY4, localIndex, envPtr);
            }
        }
    } else {
        TclEmitOpcode(INST_APPEND_STK, envPtr);
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileBreakCmd --
 *
 *      Procedure called to compile the "break" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "break" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileBreakCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    if (parsePtr->numWords != 1) {
        return TCL_ERROR;
    }

    /*
     * Emit a break instruction.
     */

    TclEmitOpcode(INST_BREAK, envPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileCatchCmd --
 *
 *      Procedure called to compile the "catch" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "catch" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileCatchCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    JumpFixup jumpFixup;
    Tcl_Token *cmdTokenPtr, *resultNameTokenPtr, *optsNameTokenPtr;
    const char *name;
    int resultIndex, optsIndex, nameChars, range;
    int savedStackDepth = envPtr->currStackDepth;
    DefineLineInformation;      /* TIP #280 */

    /*
     * If syntax does not match what we expect for [catch], do not compile.
     * Let runtime checks determine if syntax has changed.
     */

    if ((parsePtr->numWords < 2) || (parsePtr->numWords > 4)) {
        return TCL_ERROR;
    }

    /*
     * If variables were specified and the catch command is at global level
     * (not in a procedure), don't compile it inline: the payoff is too small.
     */

    if ((parsePtr->numWords >= 3) && (envPtr->procPtr == NULL)) {
        return TCL_ERROR;
    }

    /*
     * Make sure the variable names, if any, have no substitutions and just
     * refer to local scalars.
     */

    resultIndex = optsIndex = -1;
    cmdTokenPtr = TokenAfter(parsePtr->tokenPtr);
    if (parsePtr->numWords >= 3) {
        resultNameTokenPtr = TokenAfter(cmdTokenPtr);
        /* DGP */
        if (resultNameTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
            return TCL_ERROR;
        }

        name = resultNameTokenPtr[1].start;
        nameChars = resultNameTokenPtr[1].size;
        if (!TclIsLocalScalar(name, nameChars)) {
            return TCL_ERROR;
        }
        resultIndex = TclFindCompiledLocal(resultNameTokenPtr[1].start,
                resultNameTokenPtr[1].size, /*create*/ 1, envPtr->procPtr);

        /* DKF */
        if (parsePtr->numWords == 4) {
            optsNameTokenPtr = TokenAfter(resultNameTokenPtr);
            if (optsNameTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
                return TCL_ERROR;
            }
            name = optsNameTokenPtr[1].start;
            nameChars = optsNameTokenPtr[1].size;
            if (!TclIsLocalScalar(name, nameChars)) {
                return TCL_ERROR;
            }
            optsIndex = TclFindCompiledLocal(optsNameTokenPtr[1].start,
                    optsNameTokenPtr[1].size, /*create*/ 1, envPtr->procPtr);
        }
    }

    /*
     * We will compile the catch command. Emit a beginCatch instruction at the
     * start of the catch body: the subcommand it controls.
     */

    range = DeclareExceptionRange(envPtr, CATCH_EXCEPTION_RANGE);
    TclEmitInstInt4(INST_BEGIN_CATCH4, range, envPtr);

    /*
     * If the body is a simple word, compile the instructions to eval it.
     * Otherwise, compile instructions to substitute its text without
     * catching, a catch instruction that resets the stack to what it was
     * before substituting the body, and then an instruction to eval the body.
     * Care has to be taken to register the correct startOffset for the catch
     * range so that errors in the substitution are not catched [Bug 219184]
     */

    envPtr->line = mapPtr->loc[eclIndex].line[1];
    if (cmdTokenPtr->type == TCL_TOKEN_SIMPLE_WORD) {
        ExceptionRangeStarts(envPtr, range);
        CompileBody(envPtr, cmdTokenPtr, interp);
        ExceptionRangeEnds(envPtr, range);
    } else {
        CompileTokens(envPtr, cmdTokenPtr, interp);
        ExceptionRangeStarts(envPtr, range);
        TclEmitOpcode(INST_EVAL_STK, envPtr);
        ExceptionRangeEnds(envPtr, range);
    }

    /*
     * The "no errors" epilogue code: store the body's result into the
     * variable (if any), push "0" (TCL_OK) as the catch's "no error" result,
     * and jump around the "error case" code. Note that we issue the push of
     * the return options first so that if alterations happen to the current
     * interpreter state during the writing of the variable, we won't see
     * them; this results in a slightly complex instruction issuing flow
     * (can't exchange, only duplicate and pop).
     */

    if (resultIndex != -1) {
        if (optsIndex != -1) {
            TclEmitOpcode(INST_PUSH_RETURN_OPTIONS, envPtr);
            TclEmitInstInt4(INST_OVER, 1, envPtr);
        }
        if (resultIndex <= 255) {
            TclEmitInstInt1(INST_STORE_SCALAR1, resultIndex, envPtr);
        } else {
            TclEmitInstInt4(INST_STORE_SCALAR4, resultIndex, envPtr);
        }
        if (optsIndex != -1) {
            TclEmitOpcode(INST_POP, envPtr);
            if (optsIndex <= 255) {
                TclEmitInstInt1(INST_STORE_SCALAR1, optsIndex, envPtr);
            } else {
                TclEmitInstInt4(INST_STORE_SCALAR4, optsIndex, envPtr);
            }
            TclEmitOpcode(INST_POP, envPtr);
        }
    }
    TclEmitOpcode(INST_POP, envPtr);
    PushLiteral(envPtr, "0", 1);
    TclEmitForwardJump(envPtr, TCL_UNCONDITIONAL_JUMP, &jumpFixup);

    /*
     * The "error case" code: store the body's result into the variable (if
     * any), then push the error result code. The initial PC offset here is
     * the catch's error target. Note that if we are saving the return
     * options, we do that first so the preservation cannot get affected by
     * any intermediate result handling.
     */

    envPtr->currStackDepth = savedStackDepth;
    ExceptionRangeTarget(envPtr, range, catchOffset);
    if (resultIndex != -1) {
        if (optsIndex != -1) {
            TclEmitOpcode(INST_PUSH_RETURN_OPTIONS, envPtr);
        }
        TclEmitOpcode(INST_PUSH_RESULT, envPtr);
        if (resultIndex <= 255) {
            TclEmitInstInt1(INST_STORE_SCALAR1, resultIndex, envPtr);
        } else {
            TclEmitInstInt4(INST_STORE_SCALAR4, resultIndex, envPtr);
        }
        TclEmitOpcode(INST_POP, envPtr);
        if (optsIndex != -1) {
            if (optsIndex <= 255) {
                TclEmitInstInt1(INST_STORE_SCALAR1, optsIndex, envPtr);
            } else {
                TclEmitInstInt4(INST_STORE_SCALAR4, optsIndex, envPtr);
            }
            TclEmitOpcode(INST_POP, envPtr);
        }
    }
    TclEmitOpcode(INST_PUSH_RETURN_CODE, envPtr);

    /*
     * Update the target of the jump after the "no errors" code, then emit an
     * endCatch instruction at the end of the catch command.
     */

    if (TclFixupForwardJumpToHere(envPtr, &jumpFixup, 127)) {
        Tcl_Panic("TclCompileCatchCmd: bad jump distance %d",
                CurrentOffset(envPtr) - jumpFixup.codeOffset);
    }
    TclEmitOpcode(INST_END_CATCH, envPtr);

    envPtr->currStackDepth = savedStackDepth + 1;
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileContinueCmd --
 *
 *      Procedure called to compile the "continue" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "continue" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileContinueCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    /*
     * There should be no argument after the "continue".
     */

    if (parsePtr->numWords != 1) {
        return TCL_ERROR;
    }

    /*
     * Emit a continue instruction.
     */

    TclEmitOpcode(INST_CONTINUE, envPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileDict*Cmd --
 *
 *      Functions called to compile "dict" sucommands.
 *
 * Results:
 *      All return TCL_OK for a successful compile, and TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "dict" subcommand at
 *      runtime.
 *
 * Notes:
 *      The following commands are in fairly common use and are possibly worth
 *      bytecoding:
 *              dict append
 *              dict create     [*]
 *              dict exists     [*]
 *              dict for
 *              dict get        [*]
 *              dict incr
 *              dict keys       [*]
 *              dict lappend
 *              dict set
 *              dict unset
 *
 *      In practice, those that are pure-value operators (marked with [*]) can
 *      probably be left alone (except perhaps [dict get] which is very very
 *      common) and [dict update] should be considered instead (really big
 *      win!)
 *
 *----------------------------------------------------------------------
 */

int
TclCompileDictSetCmd(
    Tcl_Interp *interp,         /* Used for looking up stuff. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *tokenPtr;
    int numWords, i;
    Proc *procPtr = envPtr->procPtr;
    DefineLineInformation;      /* TIP #280 */
    Tcl_Token *varTokenPtr;
    int dictVarIndex, nameChars;
    const char *name;

    /*
     * There must be at least one argument after the command.
     */

    if (parsePtr->numWords < 4 || procPtr == NULL) {
        return TCL_ERROR;
    }

    /*
     * The dictionary variable must be a local scalar that is knowable at
     * compile time; anything else exceeds the complexity of the opcode. So
     * discover what the index is.
     */

    varTokenPtr = TokenAfter(parsePtr->tokenPtr);
    if (varTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
        return TCL_ERROR;
    }
    name = varTokenPtr[1].start;
    nameChars = varTokenPtr[1].size;
    if (!TclIsLocalScalar(name, nameChars)) {
        return TCL_ERROR;
    }
    dictVarIndex = TclFindCompiledLocal(name, nameChars, 1, procPtr);

    /*
     * Remaining words (key path and value to set) can be handled normally.
     */

    tokenPtr = TokenAfter(varTokenPtr);
    numWords = parsePtr->numWords-1;
    for (i=1 ; i<numWords ; i++) {
        CompileWord(envPtr, tokenPtr, interp, i);
        tokenPtr = TokenAfter(tokenPtr);
    }

    /*
     * Now emit the instruction to do the dict manipulation.
     */

    TclEmitInstInt4( INST_DICT_SET, numWords-2,         envPtr);
    TclEmitInt4(     dictVarIndex,                      envPtr);
    return TCL_OK;
}

int
TclCompileDictIncrCmd(
    Tcl_Interp *interp,         /* Used for looking up stuff. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Proc *procPtr = envPtr->procPtr;
    DefineLineInformation;      /* TIP #280 */
    Tcl_Token *varTokenPtr, *keyTokenPtr;
    int dictVarIndex, nameChars, incrAmount;
    const char *name;

    /*
     * There must be at least two arguments after the command.
     */

    if (parsePtr->numWords < 3 || parsePtr->numWords > 4 || procPtr == NULL) {
        return TCL_ERROR;
    }
    varTokenPtr = TokenAfter(parsePtr->tokenPtr);
    keyTokenPtr = TokenAfter(varTokenPtr);

    /*
     * Parse the increment amount, if present.
     */

    if (parsePtr->numWords == 4) {
        const char *word;
        int numBytes, code;
        Tcl_Token *incrTokenPtr;
        Tcl_Obj *intObj;

        incrTokenPtr = TokenAfter(keyTokenPtr);
        if (incrTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
            return TCL_ERROR;
        }
        word = incrTokenPtr[1].start;
        numBytes = incrTokenPtr[1].size;

        intObj = Tcl_NewStringObj(word, numBytes);
        Tcl_IncrRefCount(intObj);
        code = TclGetIntFromObj(NULL, intObj, &incrAmount);
        TclDecrRefCount(intObj);
        if (code != TCL_OK) {
            return TCL_ERROR;
        }
    } else {
        incrAmount = 1;
    }

    /*
     * The dictionary variable must be a local scalar that is knowable at
     * compile time; anything else exceeds the complexity of the opcode. So
     * discover what the index is.
     */

    if (varTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
        return TCL_ERROR;
    }
    name = varTokenPtr[1].start;
    nameChars = varTokenPtr[1].size;
    if (!TclIsLocalScalar(name, nameChars)) {
        return TCL_ERROR;
    }
    dictVarIndex = TclFindCompiledLocal(name, nameChars, 1, procPtr);

    /*
     * Emit the key and the code to actually do the increment.
     */

    CompileWord(envPtr, keyTokenPtr, interp, 3);
    TclEmitInstInt4( INST_DICT_INCR_IMM, incrAmount,    envPtr);
    TclEmitInt4(     dictVarIndex,                      envPtr);
    return TCL_OK;
}

int
TclCompileDictGetCmd(
    Tcl_Interp *interp,         /* Used for looking up stuff. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *tokenPtr;
    int numWords, i;
    DefineLineInformation;      /* TIP #280 */

    /*
     * There must be at least two arguments after the command (the single-arg
     * case is legal, but too special and magic for us to deal with here).
     */

    if (parsePtr->numWords < 3) {
        return TCL_ERROR;
    }
    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    numWords = parsePtr->numWords-1;

    /*
     * Only compile this because we need INST_DICT_GET anyway.
     */

    for (i=0 ; i<numWords ; i++) {
        CompileWord(envPtr, tokenPtr, interp, i);
        tokenPtr = TokenAfter(tokenPtr);
    }
    TclEmitInstInt4(INST_DICT_GET, numWords-1, envPtr);
    return TCL_OK;
}

int
TclCompileDictForCmd(
    Tcl_Interp *interp,         /* Used for looking up stuff. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Proc *procPtr = envPtr->procPtr;
    DefineLineInformation;      /* TIP #280 */
    Tcl_Token *varsTokenPtr, *dictTokenPtr, *bodyTokenPtr;
    int keyVarIndex, valueVarIndex, nameChars, loopRange, catchRange;
    int infoIndex, jumpDisplacement, bodyTargetOffset, emptyTargetOffset;
    int numVars, endTargetOffset;
    int savedStackDepth = envPtr->currStackDepth;
                                /* Needed because jumps confuse the stack
                                 * space calculator. */
    const char **argv;
    Tcl_DString buffer;

    /*
     * There must be at least three argument after the command.
     */

    if (parsePtr->numWords != 4 || procPtr == NULL) {
        return TCL_ERROR;
    }

    varsTokenPtr = TokenAfter(parsePtr->tokenPtr);
    dictTokenPtr = TokenAfter(varsTokenPtr);
    bodyTokenPtr = TokenAfter(dictTokenPtr);
    if (varsTokenPtr->type != TCL_TOKEN_SIMPLE_WORD ||
            bodyTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
        return TCL_ERROR;
    }

    /*
     * Check we've got a pair of variables and that they are local variables.
     * Then extract their indices in the LVT.
     */

    Tcl_DStringInit(&buffer);
    Tcl_DStringAppend(&buffer, varsTokenPtr[1].start, varsTokenPtr[1].size);
    if (Tcl_SplitList(NULL, Tcl_DStringValue(&buffer), &numVars,
            &argv) != TCL_OK) {
        Tcl_DStringFree(&buffer);
        return TCL_ERROR;
    }
    Tcl_DStringFree(&buffer);
    if (numVars != 2) {
        ckfree((char *) argv);
        return TCL_ERROR;
    }

    nameChars = strlen(argv[0]);
    if (!TclIsLocalScalar(argv[0], nameChars)) {
        ckfree((char *) argv);
        return TCL_ERROR;
    }
    keyVarIndex = TclFindCompiledLocal(argv[0], nameChars, 1, procPtr);

    nameChars = strlen(argv[1]);
    if (!TclIsLocalScalar(argv[1], nameChars)) {
        ckfree((char *) argv);
        return TCL_ERROR;
    }
    valueVarIndex = TclFindCompiledLocal(argv[1], nameChars, 1, procPtr);
    ckfree((char *) argv);

    /*
     * Allocate a temporary variable to store the iterator reference. The
     * variable will contain a Tcl_DictSearch reference which will be
     * allocated by INST_DICT_FIRST and disposed when the variable is unset
     * (at which point it should also have been finished with).
     */

    infoIndex = TclFindCompiledLocal(NULL, 0, 1, procPtr);

    /*
     * Preparation complete; issue instructions. Note that this code issues
     * fixed-sized jumps. That simplifies things a lot!
     *
     * First up, get the dictionary and start the iteration. No catching of
     * errors at this point.
     */

    CompileWord(envPtr, dictTokenPtr, interp, 3);
    TclEmitInstInt4( INST_DICT_FIRST, infoIndex,                envPtr);
    emptyTargetOffset = CurrentOffset(envPtr);
    TclEmitInstInt4( INST_JUMP_TRUE4, 0,                        envPtr);

    /*
     * Now we catch errors from here on so that we can finalize the search
     * started by Tcl_DictObjFirst above.
     */

    catchRange = DeclareExceptionRange(envPtr, CATCH_EXCEPTION_RANGE);
    TclEmitInstInt4( INST_BEGIN_CATCH4, catchRange,             envPtr);
    ExceptionRangeStarts(envPtr, catchRange);

    /*
     * Inside the iteration, write the loop variables.
     */

    bodyTargetOffset = CurrentOffset(envPtr);
    TclEmitInstInt4( INST_STORE_SCALAR4, keyVarIndex,           envPtr);
    TclEmitOpcode(   INST_POP,                                  envPtr);
    TclEmitInstInt4( INST_STORE_SCALAR4, valueVarIndex,         envPtr);
    TclEmitOpcode(   INST_POP,                                  envPtr);

    /*
     * Set up the loop exception targets.
     */

    loopRange = DeclareExceptionRange(envPtr, LOOP_EXCEPTION_RANGE);
    ExceptionRangeStarts(envPtr, loopRange);

    /*
     * Compile the loop body itself. It should be stack-neutral.
     */

    envPtr->line = mapPtr->loc[eclIndex].line[4];
    CompileBody(envPtr, bodyTokenPtr, interp);
    TclEmitOpcode(   INST_POP,                                  envPtr);

    /*
     * Both exception target ranges (error and loop) end here.
     */

    ExceptionRangeEnds(envPtr, loopRange);
    ExceptionRangeEnds(envPtr, catchRange);

    /*
     * Continue (or just normally process) by getting the next pair of items
     * from the dictionary and jumping back to the code to write them into
     * variables if there is another pair.
     */

    ExceptionRangeTarget(envPtr, loopRange, continueOffset);
    TclEmitInstInt4( INST_DICT_NEXT, infoIndex,                 envPtr);
    jumpDisplacement = bodyTargetOffset - CurrentOffset(envPtr);
    TclEmitInstInt4( INST_JUMP_FALSE4, jumpDisplacement,        envPtr);
    TclEmitOpcode(   INST_POP,                                  envPtr);
    TclEmitOpcode(   INST_POP,                                  envPtr);

    /*
     * Now do the final cleanup for the no-error case (this is where we break
     * out of the loop to) by force-terminating the iteration (if not already
     * terminated), ditching the exception info and jumping to the last
     * instruction for this command. In theory, this could be done using the
     * "finally" clause (next generated) but this is faster.
     */

    ExceptionRangeTarget(envPtr, loopRange, breakOffset);
    TclEmitInstInt4( INST_DICT_DONE, infoIndex,                 envPtr);
    TclEmitOpcode(   INST_END_CATCH,                            envPtr);
    endTargetOffset = CurrentOffset(envPtr);
    TclEmitInstInt4( INST_JUMP4, 0,                             envPtr);

    /*
     * Error handler "finally" clause, which force-terminates the iteration
     * and rethrows the error.
     */

    ExceptionRangeTarget(envPtr, catchRange, catchOffset);
    TclEmitOpcode(   INST_PUSH_RETURN_OPTIONS,                  envPtr);
    TclEmitOpcode(   INST_PUSH_RESULT,                          envPtr);
    TclEmitInstInt4( INST_DICT_DONE, infoIndex,                 envPtr);
    TclEmitOpcode(   INST_END_CATCH,                            envPtr);
    TclEmitOpcode(   INST_RETURN_STK,                           envPtr);

    /*
     * Otherwise we're done (the jump after the DICT_FIRST points here) and we
     * need to pop the bogus key/value pair (pushed to keep stack calculations
     * easy!) Note that we skip the END_CATCH. [Bug 1382528]
     */

    envPtr->currStackDepth = savedStackDepth+2;
    jumpDisplacement = CurrentOffset(envPtr) - emptyTargetOffset;
    TclUpdateInstInt4AtPc(INST_JUMP_TRUE4, jumpDisplacement,
            envPtr->codeStart + emptyTargetOffset);
    TclEmitOpcode(   INST_POP,                                  envPtr);
    TclEmitOpcode(   INST_POP,                                  envPtr);
    TclEmitInstInt4( INST_DICT_DONE, infoIndex,                 envPtr);

    /*
     * Final stage of the command (normal case) is that we push an empty
     * object. This is done last to promote peephole optimization when it's
     * dropped immediately.
     */

    jumpDisplacement = CurrentOffset(envPtr) - endTargetOffset;
    TclUpdateInstInt4AtPc(INST_JUMP4, jumpDisplacement,
            envPtr->codeStart + endTargetOffset);
    PushLiteral(envPtr, "", 0);
    return TCL_OK;
}

int
TclCompileDictUpdateCmd(
    Tcl_Interp *interp,         /* Used for looking up stuff. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Proc *procPtr = envPtr->procPtr;
    DefineLineInformation;      /* TIP #280 */
    const char *name;
    int i, nameChars, dictIndex, numVars, range, infoIndex;
    Tcl_Token **keyTokenPtrs, *dictVarTokenPtr, *bodyTokenPtr, *tokenPtr;
    DictUpdateInfo *duiPtr;
    JumpFixup jumpFixup;

    /*
     * There must be at least one argument after the command.
     */

    if (parsePtr->numWords < 5 || procPtr == NULL) {
        return TCL_ERROR;
    }

    /*
     * Parse the command. Expect the following:
     *   dict update <lit(eral)> <any> <lit> ?<any> <lit> ...? <lit>
     */

    if ((parsePtr->numWords - 1) & 1) {
        return TCL_ERROR;
    }
    numVars = (parsePtr->numWords - 3) / 2;

    /*
     * The dictionary variable must be a local scalar that is knowable at
     * compile time; anything else exceeds the complexity of the opcode. So
     * discover what the index is.
     */

    dictVarTokenPtr = TokenAfter(parsePtr->tokenPtr);
    if (dictVarTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
        return TCL_ERROR;
    }
    name = dictVarTokenPtr[1].start;
    nameChars = dictVarTokenPtr[1].size;
    if (!TclIsLocalScalar(name, nameChars)) {
        return TCL_ERROR;
    }
    dictIndex = TclFindCompiledLocal(name, nameChars, 1, procPtr);

    /*
     * Assemble the instruction metadata. This is complex enough that it is
     * represented as auxData; it holds an ordered list of variable indices
     * that are to be used.
     */

    duiPtr = (DictUpdateInfo *)
            ckalloc(sizeof(DictUpdateInfo) + sizeof(int) * (numVars - 1));
    duiPtr->length = numVars;
    keyTokenPtrs = (Tcl_Token **) TclStackAlloc(interp,
            sizeof(Tcl_Token *) * numVars);
    tokenPtr = TokenAfter(dictVarTokenPtr);

    for (i=0 ; i<numVars ; i++) {
        /*
         * Put keys to one side for later compilation to bytecode.
         */

        keyTokenPtrs[i] = tokenPtr;

        /*
         * Variables first need to be checked for sanity.
         */

        tokenPtr = TokenAfter(tokenPtr);
        if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
            ckfree((char *) duiPtr);
            TclStackFree(interp, keyTokenPtrs);
            return TCL_ERROR;
        }
        name = tokenPtr[1].start;
        nameChars = tokenPtr[1].size;
        if (!TclIsLocalScalar(name, nameChars)) {
            ckfree((char *) duiPtr);
            TclStackFree(interp, keyTokenPtrs);
            return TCL_ERROR;
        }

        /*
         * Stash the index in the auxiliary data.
         */

        duiPtr->varIndices[i] =
                TclFindCompiledLocal(name, nameChars, 1, procPtr);
        tokenPtr = TokenAfter(tokenPtr);
    }
    if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
        ckfree((char *) duiPtr);
        TclStackFree(interp, keyTokenPtrs);
        return TCL_ERROR;
    }
    bodyTokenPtr = tokenPtr;

    /*
     * The list of variables to bind is stored in auxiliary data so that it
     * can't be snagged by literal sharing and forced to shimmer dangerously.
     */

    infoIndex = TclCreateAuxData(duiPtr, &tclDictUpdateInfoType, envPtr);

    for (i=0 ; i<numVars ; i++) {
        CompileWord(envPtr, keyTokenPtrs[i], interp, i);
    }
    TclEmitInstInt4( INST_LIST, numVars,                        envPtr);
    TclEmitInstInt4( INST_DICT_UPDATE_START, dictIndex,         envPtr);
    TclEmitInt4(     infoIndex,                                 envPtr);

    range = DeclareExceptionRange(envPtr, CATCH_EXCEPTION_RANGE);
    TclEmitInstInt4( INST_BEGIN_CATCH4, range,                  envPtr);

    ExceptionRangeStarts(envPtr, range);
    CompileBody(envPtr, bodyTokenPtr, interp);
    ExceptionRangeEnds(envPtr, range);

    /*
     * Normal termination code: the stack has the key list below the result of
     * the body evaluation: swap them and finish the update code.
     */

    TclEmitOpcode(   INST_END_CATCH,                            envPtr);
    TclEmitInstInt4( INST_REVERSE, 2,                           envPtr);
    TclEmitInstInt4( INST_DICT_UPDATE_END, dictIndex,           envPtr);
    TclEmitInt4(     infoIndex,                                 envPtr);

    /*
     * Jump around the exceptional termination code.
     */

    TclEmitForwardJump(envPtr, TCL_UNCONDITIONAL_JUMP, &jumpFixup);

    /*
     * Termination code for non-ok returns: stash the result and return
     * options in the stack, bring up the key list, finish the update code,
     * and finally return with the catched return data
     */

    ExceptionRangeTarget(envPtr, range, catchOffset);
    TclEmitOpcode(   INST_PUSH_RESULT,                          envPtr);
    TclEmitOpcode(   INST_PUSH_RETURN_OPTIONS,                  envPtr);
    TclEmitOpcode(   INST_END_CATCH,                            envPtr);
    TclEmitInstInt4( INST_REVERSE, 3,                           envPtr);

    TclEmitInstInt4( INST_DICT_UPDATE_END, dictIndex,           envPtr);
    TclEmitInt4(     infoIndex,                                 envPtr);
    TclEmitOpcode(   INST_RETURN_STK,                           envPtr);

    if (TclFixupForwardJumpToHere(envPtr, &jumpFixup, 127)) {
        Tcl_Panic("TclCompileDictCmd(update): bad jump distance %d",
                CurrentOffset(envPtr) - jumpFixup.codeOffset);
    }
    TclStackFree(interp, keyTokenPtrs);
    return TCL_OK;
}

int
TclCompileDictAppendCmd(
    Tcl_Interp *interp,         /* Used for looking up stuff. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Proc *procPtr = envPtr->procPtr;
    DefineLineInformation;      /* TIP #280 */
    Tcl_Token *tokenPtr;
    int i, dictVarIndex;

    /*
     * There must be at least two argument after the command. And we impose an
     * (arbirary) safe limit; anyone exceeding it should stop worrying about
     * speed quite so much. ;-)
     */

    if (parsePtr->numWords<4 || parsePtr->numWords>100 || procPtr==NULL) {
        return TCL_ERROR;
    }

    /*
     * Get the index of the local variable that we will be working with.
     */

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
        return TCL_ERROR;
    } else {
        register const char *name = tokenPtr[1].start;
        register int nameChars = tokenPtr[1].size;

        if (!TclIsLocalScalar(name, nameChars)) {
            return TCL_ERROR;
        }
        dictVarIndex = TclFindCompiledLocal(name, nameChars, 1, procPtr);
    }

    /*
     * Produce the string to concatenate onto the dictionary entry.
     */

    tokenPtr = TokenAfter(tokenPtr);
    for (i=2 ; i<parsePtr->numWords ; i++) {
        CompileWord(envPtr, tokenPtr, interp, i);
        tokenPtr = TokenAfter(tokenPtr);
    }
    if (parsePtr->numWords > 4) {
        TclEmitInstInt1(INST_CONCAT1, parsePtr->numWords-2, envPtr);
    }

    /*
     * Do the concatenation.
     */

    TclEmitInstInt4(INST_DICT_APPEND, dictVarIndex, envPtr);
    return TCL_OK;
}

int
TclCompileDictLappendCmd(
    Tcl_Interp *interp,         /* Used for looking up stuff. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Proc *procPtr = envPtr->procPtr;
    DefineLineInformation;      /* TIP #280 */
    Tcl_Token *varTokenPtr, *keyTokenPtr, *valueTokenPtr;
    int dictVarIndex, nameChars;
    const char *name;

    /*
     * There must be three arguments after the command.
     */

    if (parsePtr->numWords != 4 || procPtr == NULL) {
        return TCL_ERROR;
    }

    varTokenPtr = TokenAfter(parsePtr->tokenPtr);
    keyTokenPtr = TokenAfter(varTokenPtr);
    valueTokenPtr = TokenAfter(keyTokenPtr);
    if (varTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
        return TCL_ERROR;
    }
    name = varTokenPtr[1].start;
    nameChars = varTokenPtr[1].size;
    if (!TclIsLocalScalar(name, nameChars)) {
        return TCL_ERROR;
    }
    dictVarIndex = TclFindCompiledLocal(name, nameChars, 1, procPtr);
    CompileWord(envPtr, keyTokenPtr, interp, 3);
    CompileWord(envPtr, valueTokenPtr, interp, 4);
    TclEmitInstInt4( INST_DICT_LAPPEND, dictVarIndex, envPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DupDictUpdateInfo, FreeDictUpdateInfo --
 *
 *      Functions to duplicate, release and print the aux data created for use
 *      with the INST_DICT_UPDATE_START and INST_DICT_UPDATE_END instructions.
 *
 * Results:
 *      DupDictUpdateInfo: a copy of the auxiliary data
 *      FreeDictUpdateInfo: none
 *      PrintDictUpdateInfo: none
 *
 * Side effects:
 *      DupDictUpdateInfo: allocates memory
 *      FreeDictUpdateInfo: releases memory
 *      PrintDictUpdateInfo: none
 *
 *----------------------------------------------------------------------
 */

static ClientData
DupDictUpdateInfo(
    ClientData clientData)
{
    DictUpdateInfo *dui1Ptr, *dui2Ptr;
    unsigned len;

    dui1Ptr = clientData;
    len = sizeof(DictUpdateInfo) + sizeof(int) * (dui1Ptr->length - 1);
    dui2Ptr = (DictUpdateInfo *) ckalloc(len);
    memcpy(dui2Ptr, dui1Ptr, len);
    return dui2Ptr;
}

static void
FreeDictUpdateInfo(
    ClientData clientData)
{
    ckfree(clientData);
}

static void
PrintDictUpdateInfo(
    ClientData clientData,
    Tcl_Obj *appendObj,
    ByteCode *codePtr,
    unsigned int pcOffset)
{
    DictUpdateInfo *duiPtr = clientData;
    int i;

    for (i=0 ; i<duiPtr->length ; i++) {
        if (i) {
            Tcl_AppendToObj(appendObj, ", ", -1);
        }
        Tcl_AppendPrintfToObj(appendObj, "%%v%u", duiPtr->varIndices[i]);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileExprCmd --
 *
 *      Procedure called to compile the "expr" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "expr" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileExprCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *firstWordPtr;

    if (parsePtr->numWords == 1) {
        return TCL_ERROR;
    }

    /*
     * TIP #280: Use the per-word line information of the current command.
     */

    envPtr->line = envPtr->extCmdMapPtr->loc[
            envPtr->extCmdMapPtr->nuloc-1].line[1];

    firstWordPtr = TokenAfter(parsePtr->tokenPtr);
    TclCompileExprWords(interp, firstWordPtr, parsePtr->numWords-1, envPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileForCmd --
 *
 *      Procedure called to compile the "for" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "for" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileForCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *startTokenPtr, *testTokenPtr, *nextTokenPtr, *bodyTokenPtr;
    JumpFixup jumpEvalCondFixup;
    int testCodeOffset, bodyCodeOffset, nextCodeOffset, jumpDist;
    int bodyRange, nextRange;
    int savedStackDepth = envPtr->currStackDepth;
    DefineLineInformation;      /* TIP #280 */

    if (parsePtr->numWords != 5) {
        return TCL_ERROR;
    }

    /*
     * If the test expression requires substitutions, don't compile the for
     * command inline. E.g., the expression might cause the loop to never
     * execute or execute forever, as in "for {} "$x > 5" {incr x} {}".
     */

    startTokenPtr = TokenAfter(parsePtr->tokenPtr);
    testTokenPtr = TokenAfter(startTokenPtr);
    if (testTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
        return TCL_ERROR;
    }

    /*
     * Bail out also if the body or the next expression require substitutions
     * in order to insure correct behaviour [Bug 219166]
     */

    nextTokenPtr = TokenAfter(testTokenPtr);
    bodyTokenPtr = TokenAfter(nextTokenPtr);
    if ((nextTokenPtr->type != TCL_TOKEN_SIMPLE_WORD)
            || (bodyTokenPtr->type != TCL_TOKEN_SIMPLE_WORD)) {
        return TCL_ERROR;
    }

    /*
     * Create ExceptionRange records for the body and the "next" command. The
     * "next" command's ExceptionRange supports break but not continue (and
     * has a -1 continueOffset).
     */

    bodyRange = DeclareExceptionRange(envPtr, LOOP_EXCEPTION_RANGE);
    nextRange = TclCreateExceptRange(LOOP_EXCEPTION_RANGE, envPtr);

    /*
     * Inline compile the initial command.
     */

    envPtr->line = mapPtr->loc[eclIndex].line[1];
    CompileBody(envPtr, startTokenPtr, interp);
    TclEmitOpcode(INST_POP, envPtr);

    /*
     * Jump to the evaluation of the condition. This code uses the "loop
     * rotation" optimisation (which eliminates one branch from the loop).
     * "for start cond next body" produces then:
     *       start
     *       goto A
     *    B: body                : bodyCodeOffset
     *       next                : nextCodeOffset, continueOffset
     *    A: cond -> result      : testCodeOffset
     *       if (result) goto B
     */

    TclEmitForwardJump(envPtr, TCL_UNCONDITIONAL_JUMP, &jumpEvalCondFixup);

    /*
     * Compile the loop body.
     */

    bodyCodeOffset = ExceptionRangeStarts(envPtr, bodyRange);
    envPtr->line = mapPtr->loc[eclIndex].line[4];
    CompileBody(envPtr, bodyTokenPtr, interp);
    ExceptionRangeEnds(envPtr, bodyRange);
    envPtr->currStackDepth = savedStackDepth + 1;
    TclEmitOpcode(INST_POP, envPtr);

    /*
     * Compile the "next" subcommand.
     */

    envPtr->currStackDepth = savedStackDepth;
    nextCodeOffset = ExceptionRangeStarts(envPtr, nextRange);
    envPtr->line = mapPtr->loc[eclIndex].line[3];
    CompileBody(envPtr, nextTokenPtr, interp);
    ExceptionRangeEnds(envPtr, nextRange);
    envPtr->currStackDepth = savedStackDepth + 1;
    TclEmitOpcode(INST_POP, envPtr);
    envPtr->currStackDepth = savedStackDepth;

    /*
     * Compile the test expression then emit the conditional jump that
     * terminates the for.
     */

    testCodeOffset = CurrentOffset(envPtr);

    jumpDist = testCodeOffset - jumpEvalCondFixup.codeOffset;
    if (TclFixupForwardJump(envPtr, &jumpEvalCondFixup, jumpDist, 127)) {
        bodyCodeOffset += 3;
        nextCodeOffset += 3;
        testCodeOffset += 3;
    }

    envPtr->line = mapPtr->loc[eclIndex].line[2];
    envPtr->currStackDepth = savedStackDepth;
    TclCompileExprWords(interp, testTokenPtr, 1, envPtr);
    envPtr->currStackDepth = savedStackDepth + 1;

    jumpDist = CurrentOffset(envPtr) - bodyCodeOffset;
    if (jumpDist > 127) {
        TclEmitInstInt4(INST_JUMP_TRUE4, -jumpDist, envPtr);
    } else {
        TclEmitInstInt1(INST_JUMP_TRUE1, -jumpDist, envPtr);
    }

    /*
     * Fix the starting points of the exception ranges (may have moved due to
     * jump type modification) and set where the exceptions target.
     */

    envPtr->exceptArrayPtr[bodyRange].codeOffset = bodyCodeOffset;
    envPtr->exceptArrayPtr[bodyRange].continueOffset = nextCodeOffset;

    envPtr->exceptArrayPtr[nextRange].codeOffset = nextCodeOffset;

    ExceptionRangeTarget(envPtr, bodyRange, breakOffset);
    ExceptionRangeTarget(envPtr, nextRange, breakOffset);

    /*
     * The for command's result is an empty string.
     */

    envPtr->currStackDepth = savedStackDepth;
    PushLiteral(envPtr, "", 0);

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileForeachCmd --
 *
 *      Procedure called to compile the "foreach" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "foreach" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileForeachCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Proc *procPtr = envPtr->procPtr;
    ForeachInfo *infoPtr;       /* Points to the structure describing this
                                 * foreach command. Stored in a AuxData
                                 * record in the ByteCode. */
    int firstValueTemp;         /* Index of the first temp var in the frame
                                 * used to point to a value list. */
    int loopCtTemp;             /* Index of temp var holding the loop's
                                 * iteration count. */
    Tcl_Token *tokenPtr, *bodyTokenPtr;
    unsigned char *jumpPc;
    JumpFixup jumpFalseFixup;
    int jumpBackDist, jumpBackOffset, infoIndex, range, bodyIndex;
    int numWords, numLists, numVars, loopIndex, tempVar, i, j, code;
    int savedStackDepth = envPtr->currStackDepth;
    DefineLineInformation;      /* TIP #280 */

    /*
     * We parse the variable list argument words and create two arrays:
     *    varcList[i] is number of variables in i-th var list.
     *    varvList[i] points to array of var names in i-th var list.
     */

    int *varcList;
    const char ***varvList;

    /*
     * If the foreach command isn't in a procedure, don't compile it inline:
     * the payoff is too small.
     */

    if (procPtr == NULL) {
        return TCL_ERROR;
    }

    numWords = parsePtr->numWords;
    if ((numWords < 4) || (numWords%2 != 0)) {
        return TCL_ERROR;
    }

    /*
     * Bail out if the body requires substitutions in order to insure correct
     * behaviour. [Bug 219166]
     */

    for (i = 0, tokenPtr = parsePtr->tokenPtr; i < numWords-1; i++) {
        tokenPtr = TokenAfter(tokenPtr);
    }
    bodyTokenPtr = tokenPtr;
    if (bodyTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
        return TCL_ERROR;
    }

    bodyIndex = i-1;

    /*
     * Allocate storage for the varcList and varvList arrays if necessary.
     */

    numLists = (numWords - 2)/2;
    varcList = (int *) TclStackAlloc(interp, numLists * sizeof(int));
    memset(varcList, 0, numLists * sizeof(int));
    varvList = (const char ***) TclStackAlloc(interp,
            numLists * sizeof(const char **));
    memset((char*) varvList, 0, numLists * sizeof(const char **));

    /*
     * Break up each var list and set the varcList and varvList arrays. Don't
     * compile the foreach inline if any var name needs substitutions or isn't
     * a scalar, or if any var list needs substitutions.
     */

    loopIndex = 0;
    for (i = 0, tokenPtr = parsePtr->tokenPtr;
            i < numWords-1;
            i++, tokenPtr = TokenAfter(tokenPtr)) {
        Tcl_DString varList;

        if (i%2 != 1) {
            continue;
        }
        if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
            code = TCL_ERROR;
            goto done;
        }

        /*
         * Lots of copying going on here. Need a ListObj wizard to show a
         * better way.
         */

        Tcl_DStringInit(&varList);
        Tcl_DStringAppend(&varList, tokenPtr[1].start, tokenPtr[1].size);
        code = Tcl_SplitList(interp, Tcl_DStringValue(&varList),
                &varcList[loopIndex], &varvList[loopIndex]);
        Tcl_DStringFree(&varList);
        if (code != TCL_OK) {
            code = TCL_ERROR;
            goto done;
        }
        numVars = varcList[loopIndex];

        /*
         * If the variable list is empty, we can enter an infinite loop when
         * the interpreted version would not. Take care to ensure this does
         * not happen. [Bug 1671138]
         */

        if (numVars == 0) {
            code = TCL_ERROR;
            goto done;
        }

        for (j = 0;  j < numVars;  j++) {
            const char *varName = varvList[loopIndex][j];

            if (!TclIsLocalScalar(varName, (int) strlen(varName))) {
                code = TCL_ERROR;
                goto done;
            }
        }
        loopIndex++;
    }

    /*
     * We will compile the foreach command. Reserve (numLists + 1) temporary
     * variables:
     *    - numLists temps to hold each value list
     *    - 1 temp for the loop counter (index of next element in each list)
     *
     * At this time we don't try to reuse temporaries; if there are two
     * nonoverlapping foreach loops, they don't share any temps.
     */

    code = TCL_OK;
    firstValueTemp = -1;
    for (loopIndex = 0;  loopIndex < numLists;  loopIndex++) {
        tempVar = TclFindCompiledLocal(NULL, /*nameChars*/ 0,
                /*create*/ 1, procPtr);
        if (loopIndex == 0) {
            firstValueTemp = tempVar;
        }
    }
    loopCtTemp = TclFindCompiledLocal(NULL, /*nameChars*/ 0,
            /*create*/ 1, procPtr);

    /*
     * Create and initialize the ForeachInfo and ForeachVarList data
     * structures describing this command. Then create a AuxData record
     * pointing to the ForeachInfo structure.
     */

    infoPtr = (ForeachInfo *) ckalloc((unsigned)
            sizeof(ForeachInfo) + numLists*sizeof(ForeachVarList *));
    infoPtr->numLists = numLists;
    infoPtr->firstValueTemp = firstValueTemp;
    infoPtr->loopCtTemp = loopCtTemp;
    for (loopIndex = 0;  loopIndex < numLists;  loopIndex++) {
        ForeachVarList *varListPtr;
        numVars = varcList[loopIndex];
        varListPtr = (ForeachVarList *) ckalloc((unsigned)
                sizeof(ForeachVarList) + numVars*sizeof(int));
        varListPtr->numVars = numVars;
        for (j = 0;  j < numVars;  j++) {
            const char *varName = varvList[loopIndex][j];
            int nameChars = strlen(varName);

            varListPtr->varIndexes[j] = TclFindCompiledLocal(varName,
                    nameChars, /*create*/ 1, procPtr);
        }
        infoPtr->varLists[loopIndex] = varListPtr;
    }
    infoIndex = TclCreateAuxData(infoPtr, &tclForeachInfoType, envPtr);

    /*
     * Create an exception record to handle [break] and [continue].
     */

    range = DeclareExceptionRange(envPtr, LOOP_EXCEPTION_RANGE);

    /*
     * Evaluate then store each value list in the associated temporary.
     */

    loopIndex = 0;
    for (i = 0, tokenPtr = parsePtr->tokenPtr;
            i < numWords-1;
            i++, tokenPtr = TokenAfter(tokenPtr)) {
        if ((i%2 == 0) && (i > 0)) {
            envPtr->line = mapPtr->loc[eclIndex].line[i];
            CompileTokens(envPtr, tokenPtr, interp);
            tempVar = (firstValueTemp + loopIndex);
            if (tempVar <= 255) {
                TclEmitInstInt1(INST_STORE_SCALAR1, tempVar, envPtr);
            } else {
                TclEmitInstInt4(INST_STORE_SCALAR4, tempVar, envPtr);
            }
            TclEmitOpcode(INST_POP, envPtr);
            loopIndex++;
        }
    }

    /*
     * Initialize the temporary var that holds the count of loop iterations.
     */

    TclEmitInstInt4(INST_FOREACH_START4, infoIndex, envPtr);

    /*
     * Top of loop code: assign each loop variable and check whether
     * to terminate the loop.
     */

    ExceptionRangeTarget(envPtr, range, continueOffset);
    TclEmitInstInt4(INST_FOREACH_STEP4, infoIndex, envPtr);
    TclEmitForwardJump(envPtr, TCL_FALSE_JUMP, &jumpFalseFixup);

    /*
     * Inline compile the loop body.
     */

    envPtr->line = mapPtr->loc[eclIndex].line[bodyIndex];
    ExceptionRangeStarts(envPtr, range);
    CompileBody(envPtr, bodyTokenPtr, interp);
    ExceptionRangeEnds(envPtr, range);
    envPtr->currStackDepth = savedStackDepth + 1;
    TclEmitOpcode(INST_POP, envPtr);

    /*
     * Jump back to the test at the top of the loop. Generate a 4 byte jump if
     * the distance to the test is > 120 bytes. This is conservative and
     * ensures that we won't have to replace this jump if we later need to
     * replace the ifFalse jump with a 4 byte jump.
     */

    jumpBackOffset = CurrentOffset(envPtr);
    jumpBackDist = jumpBackOffset-envPtr->exceptArrayPtr[range].continueOffset;
    if (jumpBackDist > 120) {
        TclEmitInstInt4(INST_JUMP4, -jumpBackDist, envPtr);
    } else {
        TclEmitInstInt1(INST_JUMP1, -jumpBackDist, envPtr);
    }

    /*
     * Fix the target of the jump after the foreach_step test.
     */

    if (TclFixupForwardJumpToHere(envPtr, &jumpFalseFixup, 127)) {
        /*
         * Update the loop body's starting PC offset since it moved down.
         */

        envPtr->exceptArrayPtr[range].codeOffset += 3;

        /*
         * Update the jump back to the test at the top of the loop since it
         * also moved down 3 bytes.
         */

        jumpBackOffset += 3;
        jumpPc = (envPtr->codeStart + jumpBackOffset);
        jumpBackDist += 3;
        if (jumpBackDist > 120) {
            TclUpdateInstInt4AtPc(INST_JUMP4, -jumpBackDist, jumpPc);
        } else {
            TclUpdateInstInt1AtPc(INST_JUMP1, -jumpBackDist, jumpPc);
        }
    }

    /*
     * Set the loop's break target.
     */

    ExceptionRangeTarget(envPtr, range, breakOffset);

    /*
     * The foreach command's result is an empty string.
     */

    envPtr->currStackDepth = savedStackDepth;
    PushLiteral(envPtr, "", 0);
    envPtr->currStackDepth = savedStackDepth + 1;

  done:
    for (loopIndex = 0;  loopIndex < numLists;  loopIndex++) {
        if (varvList[loopIndex] != NULL) {
            ckfree((char *) varvList[loopIndex]);
        }
    }
    TclStackFree(interp, (void *)varvList);
    TclStackFree(interp, varcList);
    return code;
}

/*
 *----------------------------------------------------------------------
 *
 * DupForeachInfo --
 *
 *      This procedure duplicates a ForeachInfo structure created as auxiliary
 *      data during the compilation of a foreach command.
 *
 * Results:
 *      A pointer to a newly allocated copy of the existing ForeachInfo
 *      structure is returned.
 *
 * Side effects:
 *      Storage for the copied ForeachInfo record is allocated. If the
 *      original ForeachInfo structure pointed to any ForeachVarList records,
 *      these structures are also copied and pointers to them are stored in
 *      the new ForeachInfo record.
 *
 *----------------------------------------------------------------------
 */

static ClientData
DupForeachInfo(
    ClientData clientData)      /* The foreach command's compilation auxiliary
                                 * data to duplicate. */
{
    register ForeachInfo *srcPtr = clientData;
    ForeachInfo *dupPtr;
    register ForeachVarList *srcListPtr, *dupListPtr;
    int numVars, i, j, numLists = srcPtr->numLists;

    dupPtr = (ForeachInfo *) ckalloc((unsigned)
            sizeof(ForeachInfo) + numLists*sizeof(ForeachVarList *));
    dupPtr->numLists = numLists;
    dupPtr->firstValueTemp = srcPtr->firstValueTemp;
    dupPtr->loopCtTemp = srcPtr->loopCtTemp;

    for (i = 0;  i < numLists;  i++) {
        srcListPtr = srcPtr->varLists[i];
        numVars = srcListPtr->numVars;
        dupListPtr = (ForeachVarList *) ckalloc((unsigned)
                sizeof(ForeachVarList) + numVars*sizeof(int));
        dupListPtr->numVars = numVars;
        for (j = 0;  j < numVars;  j++) {
            dupListPtr->varIndexes[j] = srcListPtr->varIndexes[j];
        }
        dupPtr->varLists[i] = dupListPtr;
    }
    return dupPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * FreeForeachInfo --
 *
 *      Procedure to free a ForeachInfo structure created as auxiliary data
 *      during the compilation of a foreach command.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Storage for the ForeachInfo structure pointed to by the ClientData
 *      argument is freed as is any ForeachVarList record pointed to by the
 *      ForeachInfo structure.
 *
 *----------------------------------------------------------------------
 */

static void
FreeForeachInfo(
    ClientData clientData)      /* The foreach command's compilation auxiliary
                                 * data to free. */
{
    register ForeachInfo *infoPtr = clientData;
    register ForeachVarList *listPtr;
    int numLists = infoPtr->numLists;
    register int i;

    for (i = 0;  i < numLists;  i++) {
        listPtr = infoPtr->varLists[i];
        ckfree((char *) listPtr);
    }
    ckfree((char *) infoPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * PrintForeachInfo --
 *
 *      Function to write a human-readable representation of a ForeachInfo
 *      structure to stdout for debugging.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static void
PrintForeachInfo(
    ClientData clientData,
    Tcl_Obj *appendObj,
    ByteCode *codePtr,
    unsigned int pcOffset)
{
    register ForeachInfo *infoPtr = clientData;
    register ForeachVarList *varsPtr;
    int i, j;

    Tcl_AppendToObj(appendObj, "data=[", -1);

    for (i=0 ; i<infoPtr->numLists ; i++) {
        if (i) {
            Tcl_AppendToObj(appendObj, ", ", -1);
        }
        Tcl_AppendPrintfToObj(appendObj, "%%v%u",
                (unsigned) (infoPtr->firstValueTemp + i));
    }
    Tcl_AppendPrintfToObj(appendObj, "], loop=%%v%u",
            (unsigned) infoPtr->loopCtTemp);
    for (i=0 ; i<infoPtr->numLists ; i++) {
        if (i) {
            Tcl_AppendToObj(appendObj, ",", -1);
        }
        Tcl_AppendPrintfToObj(appendObj, "\n\t\t it%%v%u\t[",
                (unsigned) (infoPtr->firstValueTemp + i));
        varsPtr = infoPtr->varLists[i];
        for (j=0 ; j<varsPtr->numVars ; j++) {
            if (j) {
                Tcl_AppendToObj(appendObj, ", ", -1);
            }
            Tcl_AppendPrintfToObj(appendObj, "%%v%u",
                    (unsigned) varsPtr->varIndexes[j]);
        }
        Tcl_AppendToObj(appendObj, "]", -1);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileIfCmd --
 *
 *      Procedure called to compile the "if" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "if" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileIfCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    JumpFixupArray jumpFalseFixupArray;
                                /* Used to fix the ifFalse jump after each
                                 * test when its target PC is determined. */
    JumpFixupArray jumpEndFixupArray;
                                /* Used to fix the jump after each "then" body
                                 * to the end of the "if" when that PC is
                                 * determined. */
    Tcl_Token *tokenPtr, *testTokenPtr;
    int jumpIndex = 0;          /* Avoid compiler warning. */
    int jumpFalseDist, numWords, wordIdx, numBytes, j, code;
    const char *word;
    int savedStackDepth = envPtr->currStackDepth;
                                /* Saved stack depth at the start of the first
                                 * test; the envPtr current depth is restored
                                 * to this value at the start of each test. */
    int realCond = 1;           /* Set to 0 for static conditions:
                                 * "if 0 {..}" */
    int boolVal;                /* Value of static condition. */
    int compileScripts = 1;
    DefineLineInformation;      /* TIP #280 */

    /*
     * Only compile the "if" command if all arguments are simple words, in
     * order to insure correct substitution [Bug 219166]
     */

    tokenPtr = parsePtr->tokenPtr;
    wordIdx = 0;
    numWords = parsePtr->numWords;

    for (wordIdx = 0; wordIdx < numWords; wordIdx++) {
        if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
            return TCL_ERROR;
        }
        tokenPtr = TokenAfter(tokenPtr);
    }

    TclInitJumpFixupArray(&jumpFalseFixupArray);
    TclInitJumpFixupArray(&jumpEndFixupArray);
    code = TCL_OK;

    /*
     * Each iteration of this loop compiles one "if expr ?then? body" or
     * "elseif expr ?then? body" clause.
     */

    tokenPtr = parsePtr->tokenPtr;
    wordIdx = 0;
    while (wordIdx < numWords) {
        /*
         * Stop looping if the token isn't "if" or "elseif".
         */

        word = tokenPtr[1].start;
        numBytes = tokenPtr[1].size;
        if ((tokenPtr == parsePtr->tokenPtr)
                || ((numBytes == 6) && (strncmp(word, "elseif", 6) == 0))) {
            tokenPtr = TokenAfter(tokenPtr);
            wordIdx++;
        } else {
            break;
        }
        if (wordIdx >= numWords) {
            code = TCL_ERROR;
            goto done;
        }

        /*
         * Compile the test expression then emit the conditional jump around
         * the "then" part.
         */

        envPtr->currStackDepth = savedStackDepth;
        testTokenPtr = tokenPtr;

        if (realCond) {
            /*
             * Find out if the condition is a constant.
             */

            Tcl_Obj *boolObj = Tcl_NewStringObj(testTokenPtr[1].start,
                    testTokenPtr[1].size);
            Tcl_IncrRefCount(boolObj);
            code = Tcl_GetBooleanFromObj(NULL, boolObj, &boolVal);
            TclDecrRefCount(boolObj);
            if (code == TCL_OK) {
                /*
                 * A static condition.
                 */

                realCond = 0;
                if (!boolVal) {
                    compileScripts = 0;
                }
            } else {
                envPtr->line = mapPtr->loc[eclIndex].line[wordIdx];
                Tcl_ResetResult(interp);
                TclCompileExprWords(interp, testTokenPtr, 1, envPtr);
                if (jumpFalseFixupArray.next >= jumpFalseFixupArray.end) {
                    TclExpandJumpFixupArray(&jumpFalseFixupArray);
                }
                jumpIndex = jumpFalseFixupArray.next;
                jumpFalseFixupArray.next++;
                TclEmitForwardJump(envPtr, TCL_FALSE_JUMP,
                        jumpFalseFixupArray.fixup+jumpIndex);
            }
            code = TCL_OK;
        }

        /*
         * Skip over the optional "then" before the then clause.
         */

        tokenPtr = TokenAfter(testTokenPtr);
        wordIdx++;
        if (wordIdx >= numWords) {
            code = TCL_ERROR;
            goto done;
        }
        if (tokenPtr->type == TCL_TOKEN_SIMPLE_WORD) {
            word = tokenPtr[1].start;
            numBytes = tokenPtr[1].size;
            if ((numBytes == 4) && (strncmp(word, "then", 4) == 0)) {
                tokenPtr = TokenAfter(tokenPtr);
                wordIdx++;
                if (wordIdx >= numWords) {
                    code = TCL_ERROR;
                    goto done;
                }
            }
        }

        /*
         * Compile the "then" command body.
         */

        if (compileScripts) {
            envPtr->line = mapPtr->loc[eclIndex].line[wordIdx];
            envPtr->currStackDepth = savedStackDepth;
            CompileBody(envPtr, tokenPtr, interp);
        }

        if (realCond) {
            /*
             * Jump to the end of the "if" command. Both jumpFalseFixupArray
             * and jumpEndFixupArray are indexed by "jumpIndex".
             */

            if (jumpEndFixupArray.next >= jumpEndFixupArray.end) {
                TclExpandJumpFixupArray(&jumpEndFixupArray);
            }
            jumpEndFixupArray.next++;
            TclEmitForwardJump(envPtr, TCL_UNCONDITIONAL_JUMP,
                    jumpEndFixupArray.fixup+jumpIndex);

            /*
             * Fix the target of the jumpFalse after the test. Generate a 4
             * byte jump if the distance is > 120 bytes. This is conservative,
             * and ensures that we won't have to replace this jump if we later
             * also need to replace the proceeding jump to the end of the "if"
             * with a 4 byte jump.
             */

            if (TclFixupForwardJumpToHere(envPtr,
                    jumpFalseFixupArray.fixup+jumpIndex, 120)) {
                /*
                 * Adjust the code offset for the proceeding jump to the end
                 * of the "if" command.
                 */

                jumpEndFixupArray.fixup[jumpIndex].codeOffset += 3;
            }
        } else if (boolVal) {
            /*
             * We were processing an "if 1 {...}"; stop compiling scripts.
             */

            compileScripts = 0;
        } else {
            /*
             * We were processing an "if 0 {...}"; reset so that the rest
             * (elseif, else) is compiled correctly.
             */

            realCond = 1;
            compileScripts = 1;
        }

        tokenPtr = TokenAfter(tokenPtr);
        wordIdx++;
    }

    /*
     * Restore the current stack depth in the environment; the "else" clause
     * (or its default) will add 1 to this.
     */

    envPtr->currStackDepth = savedStackDepth;

    /*
     * Check for the optional else clause. Do not compile anything if this was
     * an "if 1 {...}" case.
     */

    if ((wordIdx < numWords) && (tokenPtr->type == TCL_TOKEN_SIMPLE_WORD)) {
        /*
         * There is an else clause. Skip over the optional "else" word.
         */

        word = tokenPtr[1].start;
        numBytes = tokenPtr[1].size;
        if ((numBytes == 4) && (strncmp(word, "else", 4) == 0)) {
            tokenPtr = TokenAfter(tokenPtr);
            wordIdx++;
            if (wordIdx >= numWords) {
                code = TCL_ERROR;
                goto done;
            }
        }

        if (compileScripts) {
            /*
             * Compile the else command body.
             */

            envPtr->line = mapPtr->loc[eclIndex].line[wordIdx];
            CompileBody(envPtr, tokenPtr, interp);
        }

        /*
         * Make sure there are no words after the else clause.
         */

        wordIdx++;
        if (wordIdx < numWords) {
            code = TCL_ERROR;
            goto done;
        }
    } else {
        /*
         * No else clause: the "if" command's result is an empty string.
         */

        if (compileScripts) {
            PushLiteral(envPtr, "", 0);
        }
    }

    /*
     * Fix the unconditional jumps to the end of the "if" command.
     */

    for (j = jumpEndFixupArray.next;  j > 0;  j--) {
        jumpIndex = (j - 1);    /* i.e. process the closest jump first. */
        if (TclFixupForwardJumpToHere(envPtr,
                jumpEndFixupArray.fixup+jumpIndex, 127)) {
            /*
             * Adjust the immediately preceeding "ifFalse" jump. We moved it's
             * target (just after this jump) down three bytes.
             */

            unsigned char *ifFalsePc = envPtr->codeStart
                    + jumpFalseFixupArray.fixup[jumpIndex].codeOffset;
            unsigned char opCode = *ifFalsePc;

            if (opCode == INST_JUMP_FALSE1) {
                jumpFalseDist = TclGetInt1AtPtr(ifFalsePc + 1);
                jumpFalseDist += 3;
                TclStoreInt1AtPtr(jumpFalseDist, (ifFalsePc + 1));
            } else if (opCode == INST_JUMP_FALSE4) {
                jumpFalseDist = TclGetInt4AtPtr(ifFalsePc + 1);
                jumpFalseDist += 3;
                TclStoreInt4AtPtr(jumpFalseDist, (ifFalsePc + 1));
            } else {
                Tcl_Panic("TclCompileIfCmd: unexpected opcode \"%d\" updating ifFalse jump", (int) opCode);
            }
        }
    }

    /*
     * Free the jumpFixupArray array if malloc'ed storage was used.
     */

  done:
    envPtr->currStackDepth = savedStackDepth + 1;
    TclFreeJumpFixupArray(&jumpFalseFixupArray);
    TclFreeJumpFixupArray(&jumpEndFixupArray);
    return code;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileIncrCmd --
 *
 *      Procedure called to compile the "incr" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "incr" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileIncrCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *varTokenPtr, *incrTokenPtr;
    int simpleVarName, isScalar, localIndex, haveImmValue, immValue;
    DefineLineInformation;      /* TIP #280 */

    if ((parsePtr->numWords != 2) && (parsePtr->numWords != 3)) {
        return TCL_ERROR;
    }

    varTokenPtr = TokenAfter(parsePtr->tokenPtr);

    PushVarName(interp, varTokenPtr, envPtr, TCL_NO_LARGE_INDEX|TCL_CREATE_VAR,
                &localIndex, &simpleVarName, &isScalar,
                mapPtr->loc[eclIndex].line[1]);

    /*
     * If an increment is given, push it, but see first if it's a small
     * integer.
     */

    haveImmValue = 0;
    immValue = 1;
    if (parsePtr->numWords == 3) {
        incrTokenPtr = TokenAfter(varTokenPtr);
        if (incrTokenPtr->type == TCL_TOKEN_SIMPLE_WORD) {
            const char *word = incrTokenPtr[1].start;
            int numBytes = incrTokenPtr[1].size;
            int code;
            Tcl_Obj *intObj = Tcl_NewStringObj(word, numBytes);
            Tcl_IncrRefCount(intObj);
            code = TclGetIntFromObj(NULL, intObj, &immValue);
            TclDecrRefCount(intObj);
            if ((code == TCL_OK) && (-127 <= immValue) && (immValue <= 127)) {
                haveImmValue = 1;
            }
            if (!haveImmValue) {
                PushLiteral(envPtr, word, numBytes);
            }
        } else {
            envPtr->line = mapPtr->loc[eclIndex].line[2];
            CompileTokens(envPtr, incrTokenPtr, interp);
        }
    } else {                    /* No incr amount given so use 1. */
        haveImmValue = 1;
    }

    /*
     * Emit the instruction to increment the variable.
     */

    if (simpleVarName) {
        if (isScalar) {
            if (localIndex >= 0) {
                if (haveImmValue) {
                    TclEmitInstInt1(INST_INCR_SCALAR1_IMM, localIndex, envPtr);
                    TclEmitInt1(immValue, envPtr);
                } else {
                    TclEmitInstInt1(INST_INCR_SCALAR1, localIndex, envPtr);
                }
            } else {
                if (haveImmValue) {
                    TclEmitInstInt1(INST_INCR_SCALAR_STK_IMM, immValue, envPtr);
                } else {
                    TclEmitOpcode(INST_INCR_SCALAR_STK, envPtr);
                }
            }
        } else {
            if (localIndex >= 0) {
                if (haveImmValue) {
                    TclEmitInstInt1(INST_INCR_ARRAY1_IMM, localIndex, envPtr);
                    TclEmitInt1(immValue, envPtr);
                } else {
                    TclEmitInstInt1(INST_INCR_ARRAY1, localIndex, envPtr);
                }
            } else {
                if (haveImmValue) {
                    TclEmitInstInt1(INST_INCR_ARRAY_STK_IMM, immValue, envPtr);
                } else {
                    TclEmitOpcode(INST_INCR_ARRAY_STK, envPtr);
                }
            }
        }
    } else {                    /* Non-simple variable name. */
        if (haveImmValue) {
            TclEmitInstInt1(INST_INCR_STK_IMM, immValue, envPtr);
        } else {
            TclEmitOpcode(INST_INCR_STK, envPtr);
        }
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileLappendCmd --
 *
 *      Procedure called to compile the "lappend" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "lappend" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileLappendCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *varTokenPtr;
    int simpleVarName, isScalar, localIndex, numWords;
    DefineLineInformation;      /* TIP #280 */

    /*
     * If we're not in a procedure, don't compile.
     */

    if (envPtr->procPtr == NULL) {
        return TCL_ERROR;
    }

    numWords = parsePtr->numWords;
    if (numWords == 1) {
        return TCL_ERROR;
    }
    if (numWords != 3) {
        /*
         * LAPPEND instructions currently only handle one value appends.
         */

        return TCL_ERROR;
    }

    /*
     * Decide if we can use a frame slot for the var/array name or if we
     * need to emit code to compute and push the name at runtime. We use a
     * frame slot (entry in the array of local vars) if we are compiling a
     * procedure body and if the name is simple text that does not include
     * namespace qualifiers.
     */

    varTokenPtr = TokenAfter(parsePtr->tokenPtr);

    PushVarName(interp, varTokenPtr, envPtr, TCL_CREATE_VAR,
                &localIndex, &simpleVarName, &isScalar,
                mapPtr->loc[eclIndex].line[1]);

    /*
     * If we are doing an assignment, push the new value. In the no values
     * case, create an empty object.
     */

    if (numWords > 2) {
        Tcl_Token *valueTokenPtr = TokenAfter(varTokenPtr);
        CompileWord(envPtr, valueTokenPtr, interp, 2);
    }

    /*
     * Emit instructions to set/get the variable.
     */

    /*
     * The *_STK opcodes should be refactored to make better use of existing
     * LOAD/STORE instructions.
     */

    if (simpleVarName) {
        if (isScalar) {
            if (localIndex < 0) {
                TclEmitOpcode(INST_LAPPEND_STK, envPtr);
            } else if (localIndex <= 255) {
                TclEmitInstInt1(INST_LAPPEND_SCALAR1, localIndex, envPtr);
            } else {
                TclEmitInstInt4(INST_LAPPEND_SCALAR4, localIndex, envPtr);
            }
        } else {
            if (localIndex < 0) {
                TclEmitOpcode(INST_LAPPEND_ARRAY_STK, envPtr);
            } else if (localIndex <= 255) {
                TclEmitInstInt1(INST_LAPPEND_ARRAY1, localIndex, envPtr);
            } else {
                TclEmitInstInt4(INST_LAPPEND_ARRAY4, localIndex, envPtr);
            }
        }
    } else {
        TclEmitOpcode(INST_LAPPEND_STK, envPtr);
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileLassignCmd --
 *
 *      Procedure called to compile the "lassign" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "lassign" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileLassignCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *tokenPtr;
    int simpleVarName, isScalar, localIndex, numWords, idx;
    DefineLineInformation;      /* TIP #280 */

    numWords = parsePtr->numWords;

    /*
     * Check for command syntax error, but we'll punt that to runtime.
     */

    if (numWords < 3) {
        return TCL_ERROR;
    }

    /*
     * Generate code to push list being taken apart by [lassign].
     */

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    CompileWord(envPtr, tokenPtr, interp, 1);

    /*
     * Generate code to assign values from the list to variables.
     */

    for (idx=0 ; idx<numWords-2 ; idx++) {
        tokenPtr = TokenAfter(tokenPtr);

        /*
         * Generate the next variable name.
         */

        PushVarName(interp, tokenPtr, envPtr, TCL_CREATE_VAR, &localIndex,
                &simpleVarName, &isScalar, mapPtr->loc[eclIndex].line[idx+2]);

        /*
         * Emit instructions to get the idx'th item out of the list value on
         * the stack and assign it to the variable.
         */

        if (simpleVarName) {
            if (isScalar) {
                if (localIndex >= 0) {
                    TclEmitOpcode(INST_DUP, envPtr);
                    TclEmitInstInt4(INST_LIST_INDEX_IMM, idx, envPtr);
                    if (localIndex <= 255) {
                        TclEmitInstInt1(INST_STORE_SCALAR1,localIndex,envPtr);
                    } else {
                        TclEmitInstInt4(INST_STORE_SCALAR4,localIndex,envPtr);
                    }
                } else {
                    TclEmitInstInt4(INST_OVER, 1, envPtr);
                    TclEmitInstInt4(INST_LIST_INDEX_IMM, idx, envPtr);
                    TclEmitOpcode(INST_STORE_SCALAR_STK, envPtr);
                }
            } else {
                if (localIndex >= 0) {
                    TclEmitInstInt4(INST_OVER, 1, envPtr);
                    TclEmitInstInt4(INST_LIST_INDEX_IMM, idx, envPtr);
                    if (localIndex <= 255) {
                        TclEmitInstInt1(INST_STORE_ARRAY1, localIndex, envPtr);
                    } else {
                        TclEmitInstInt4(INST_STORE_ARRAY4, localIndex, envPtr);
                    }
                } else {
                    TclEmitInstInt4(INST_OVER, 2, envPtr);
                    TclEmitInstInt4(INST_LIST_INDEX_IMM, idx, envPtr);
                    TclEmitOpcode(INST_STORE_ARRAY_STK, envPtr);
                }
            }
        } else {
            TclEmitInstInt4(INST_OVER, 1, envPtr);
            TclEmitInstInt4(INST_LIST_INDEX_IMM, idx, envPtr);
            TclEmitOpcode(INST_STORE_STK, envPtr);
        }
        TclEmitOpcode(INST_POP, envPtr);
    }

    /*
     * Generate code to leave the rest of the list on the stack.
     */

    TclEmitInstInt4(INST_LIST_RANGE_IMM, idx, envPtr);
    TclEmitInt4(-2, envPtr);    /* -2 == "end" */

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileLindexCmd --
 *
 *      Procedure called to compile the "lindex" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "lindex" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileLindexCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *idxTokenPtr, *valTokenPtr;
    int i, numWords = parsePtr->numWords;
    DefineLineInformation;      /* TIP #280 */

    /*
     * Quit if too few args.
     */

    if (numWords <= 1) {
        return TCL_ERROR;
    }

    valTokenPtr = TokenAfter(parsePtr->tokenPtr);
    if (numWords != 3) {
        goto emitComplexLindex;
    }

    idxTokenPtr = TokenAfter(valTokenPtr);
    if (idxTokenPtr->type == TCL_TOKEN_SIMPLE_WORD) {
        Tcl_Obj *tmpObj;
        int idx, result;

        tmpObj = Tcl_NewStringObj(idxTokenPtr[1].start, idxTokenPtr[1].size);
        result = TclGetIntFromObj(NULL, tmpObj, &idx);
        TclDecrRefCount(tmpObj);

        if (result == TCL_OK && idx >= 0) {
            /*
             * All checks have been completed, and we have exactly this
             * construct:
             *   lindex <arbitraryValue> <posInt>
             * This is best compiled as a push of the arbitrary value followed
             * by an "immediate lindex" which is the most efficient variety.
             */

            CompileWord(envPtr, valTokenPtr, interp, 1);
            TclEmitInstInt4(INST_LIST_INDEX_IMM, idx, envPtr);
            return TCL_OK;
        }

        /*
         * If the conversion failed or the value was negative, we just keep on
         * going with the more complex compilation.
         */
    }

    /*
     * Push the operands onto the stack.
     */

  emitComplexLindex:
    for (i=1 ; i<numWords ; i++) {
        CompileWord(envPtr, valTokenPtr, interp, i);
        valTokenPtr = TokenAfter(valTokenPtr);
    }

    /*
     * Emit INST_LIST_INDEX if objc==3, or INST_LIST_INDEX_MULTI if there are
     * multiple index args.
     */

    if (numWords == 3) {
        TclEmitOpcode(INST_LIST_INDEX, envPtr);
    } else {
        TclEmitInstInt4(INST_LIST_INDEX_MULTI, numWords-1, envPtr);
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileListCmd --
 *
 *      Procedure called to compile the "list" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "list" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileListCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    DefineLineInformation;      /* TIP #280 */

    /*
     * If we're not in a procedure, don't compile.
     */

    if (envPtr->procPtr == NULL) {
        return TCL_ERROR;
    }

    if (parsePtr->numWords == 1) {
        /*
         * [list] without arguments just pushes an empty object.
         */

        PushLiteral(envPtr, "", 0);
    } else {
        /*
         * Push the all values onto the stack.
         */

        Tcl_Token *valueTokenPtr;
        int i, numWords;

        numWords = parsePtr->numWords;

        valueTokenPtr = TokenAfter(parsePtr->tokenPtr);
        for (i = 1; i < numWords; i++) {
            CompileWord(envPtr, valueTokenPtr, interp, i);
            valueTokenPtr = TokenAfter(valueTokenPtr);
        }
        TclEmitInstInt4(INST_LIST, numWords - 1, envPtr);
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileLlengthCmd --
 *
 *      Procedure called to compile the "llength" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "llength" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileLlengthCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *varTokenPtr;
    DefineLineInformation;      /* TIP #280 */

    if (parsePtr->numWords != 2) {
        return TCL_ERROR;
    }
    varTokenPtr = TokenAfter(parsePtr->tokenPtr);

    CompileWord(envPtr, varTokenPtr, interp, 1);
    TclEmitOpcode(INST_LIST_LENGTH, envPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileLsetCmd --
 *
 *      Procedure called to compile the "lset" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "lset" command at
 *      runtime.
 *
 * The general template for execution of the "lset" command is:
 *      (1) Instructions to push the variable name, unless the variable is
 *          local to the stack frame.
 *      (2) If the variable is an array element, instructions to push the
 *          array element name.
 *      (3) Instructions to push each of zero or more "index" arguments to the
 *          stack, followed with the "newValue" element.
 *      (4) Instructions to duplicate the variable name and/or array element
 *          name onto the top of the stack, if either was pushed at steps (1)
 *          and (2).
 *      (5) The appropriate INST_LOAD_* instruction to place the original
 *          value of the list variable at top of stack.
 *      (6) At this point, the stack contains:
 *              varName? arrayElementName? index1 index2 ... newValue oldList
 *          The compiler emits one of INST_LSET_FLAT or INST_LSET_LIST
 *          according as whether there is exactly one index element (LIST) or
 *          either zero or else two or more (FLAT). This instruction removes
 *          everything from the stack except for the two names and pushes the
 *          new value of the variable.
 *      (7) Finally, INST_STORE_* stores the new value in the variable and
 *          cleans up the stack.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileLsetCmd(
    Tcl_Interp *interp,         /* Tcl interpreter for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the
                                 * command. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds the resulting instructions. */
{
    int tempDepth;              /* Depth used for emitting one part of the
                                 * code burst. */
    Tcl_Token *varTokenPtr;     /* Pointer to the Tcl_Token representing the
                                 * parse of the variable name. */
    int localIndex;             /* Index of var in local var table. */
    int simpleVarName;          /* Flag == 1 if var name is simple. */
    int isScalar;               /* Flag == 1 if scalar, 0 if array. */
    int i;
    DefineLineInformation;      /* TIP #280 */

    /*
     * Check argument count.
     */

    if (parsePtr->numWords < 3) {
        /*
         * Fail at run time, not in compilation.
         */

        return TCL_ERROR;
    }

    /*
     * Decide if we can use a frame slot for the var/array name or if we need
     * to emit code to compute and push the name at runtime. We use a frame
     * slot (entry in the array of local vars) if we are compiling a procedure
     * body and if the name is simple text that does not include namespace
     * qualifiers.
     */

    varTokenPtr = TokenAfter(parsePtr->tokenPtr);
    PushVarName(interp, varTokenPtr, envPtr, TCL_CREATE_VAR,
                &localIndex, &simpleVarName, &isScalar,
                mapPtr->loc[eclIndex].line[1]);

    /*
     * Push the "index" args and the new element value.
     */

    for (i=2 ; i<parsePtr->numWords ; ++i) {
        varTokenPtr = TokenAfter(varTokenPtr);
        CompileWord(envPtr, varTokenPtr, interp, i);
    }

    /*
     * Duplicate the variable name if it's been pushed.
     */

    if (!simpleVarName || localIndex < 0) {
        if (!simpleVarName || isScalar) {
            tempDepth = parsePtr->numWords - 2;
        } else {
            tempDepth = parsePtr->numWords - 1;
        }
        TclEmitInstInt4(INST_OVER, tempDepth, envPtr);
    }

    /*
     * Duplicate an array index if one's been pushed.
     */

    if (simpleVarName && !isScalar) {
        if (localIndex < 0) {
            tempDepth = parsePtr->numWords - 1;
        } else {
            tempDepth = parsePtr->numWords - 2;
        }
        TclEmitInstInt4(INST_OVER, tempDepth, envPtr);
    }

    /*
     * Emit code to load the variable's value.
     */

    if (!simpleVarName) {
        TclEmitOpcode(INST_LOAD_STK, envPtr);
    } else if (isScalar) {
        if (localIndex < 0) {
            TclEmitOpcode(INST_LOAD_SCALAR_STK, envPtr);
        } else if (localIndex < 0x100) {
            TclEmitInstInt1(INST_LOAD_SCALAR1, localIndex, envPtr);
        } else {
            TclEmitInstInt4(INST_LOAD_SCALAR4, localIndex, envPtr);
        }
    } else {
        if (localIndex < 0) {
            TclEmitOpcode(INST_LOAD_ARRAY_STK, envPtr);
        } else if (localIndex < 0x100) {
            TclEmitInstInt1(INST_LOAD_ARRAY1, localIndex, envPtr);
        } else {
            TclEmitInstInt4(INST_LOAD_ARRAY4, localIndex, envPtr);
        }
    }

    /*
     * Emit the correct variety of 'lset' instruction.
     */

    if (parsePtr->numWords == 4) {
        TclEmitOpcode(INST_LSET_LIST, envPtr);
    } else {
        TclEmitInstInt4(INST_LSET_FLAT, parsePtr->numWords-1, envPtr);
    }

    /*
     * Emit code to put the value back in the variable.
     */

    if (!simpleVarName) {
        TclEmitOpcode(INST_STORE_STK, envPtr);
    } else if (isScalar) {
        if (localIndex < 0) {
            TclEmitOpcode(INST_STORE_SCALAR_STK, envPtr);
        } else if (localIndex < 0x100) {
            TclEmitInstInt1(INST_STORE_SCALAR1, localIndex, envPtr);
        } else {
            TclEmitInstInt4(INST_STORE_SCALAR4, localIndex, envPtr);
        }
    } else {
        if (localIndex < 0) {
            TclEmitOpcode(INST_STORE_ARRAY_STK, envPtr);
        } else if (localIndex < 0x100) {
            TclEmitInstInt1(INST_STORE_ARRAY1, localIndex, envPtr);
        } else {
            TclEmitInstInt4(INST_STORE_ARRAY4, localIndex, envPtr);
        }
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileRegexpCmd --
 *
 *      Procedure called to compile the "regexp" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "regexp" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileRegexpCmd(
    Tcl_Interp *interp,         /* Tcl interpreter for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the
                                 * command. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds the resulting instructions. */
{
    Tcl_Token *varTokenPtr;     /* Pointer to the Tcl_Token representing the
                                 * parse of the RE or string. */
    int i, len, nocase, exact, sawLast, simple;
    char *str;
    DefineLineInformation;      /* TIP #280 */

    /*
     * We are only interested in compiling simple regexp cases. Currently
     * supported compile cases are:
     *   regexp ?-nocase? ?--? staticString $var
     *   regexp ?-nocase? ?--? {^staticString$} $var
     */

    if (parsePtr->numWords < 3) {
        return TCL_ERROR;
    }

    simple = 0;
    nocase = 0;
    sawLast = 0;
    varTokenPtr = parsePtr->tokenPtr;

    /*
     * We only look for -nocase and -- as options. Everything else gets pushed
     * to runtime execution. This is different than regexp's runtime option
     * handling, but satisfies our stricter needs.
     */

    for (i = 1; i < parsePtr->numWords - 2; i++) {
        varTokenPtr = TokenAfter(varTokenPtr);
        if (varTokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
            /*
             * Not a simple string, so punt to runtime.
             */

            return TCL_ERROR;
        }
        str = (char *) varTokenPtr[1].start;
        len = varTokenPtr[1].size;
        if ((len == 2) && (str[0] == '-') && (str[1] == '-')) {
            sawLast++;
            i++;
            break;
        } else if ((len > 1) && (strncmp(str,"-nocase",(unsigned)len) == 0)) {
            nocase = 1;
        } else {
            /*
             * Not an option we recognize.
             */

            return TCL_ERROR;
        }
    }

    if ((parsePtr->numWords - i) != 2) {
        /*
         * We don't support capturing to variables.
         */

        return TCL_ERROR;
    }

    /*
     * Get the regexp string. If it is not a simple string or can't be
     * converted to a glob pattern, push the word for the INST_REGEXP.
     * Keep changes here in sync with TclCompileSwitchCmd Switch_Regexp.
     */

    varTokenPtr = TokenAfter(varTokenPtr);

    if (varTokenPtr->type == TCL_TOKEN_SIMPLE_WORD) {
        Tcl_DString ds;

        str = (char *) varTokenPtr[1].start;
        len = varTokenPtr[1].size;
        /*
         * If it has a '-', it could be an incorrectly formed regexp command.
         */

        if ((*str == '-') && !sawLast) {
            return TCL_ERROR;
        }

        if (len == 0) {
            /*
             * The semantics of regexp are always match on re == "".
             */

            PushLiteral(envPtr, "1", 1);
            return TCL_OK;
        }

        /*
         * Attempt to convert pattern to glob.  If successful, push the
         * converted pattern as a literal.
         */

        if (TclReToGlob(NULL, varTokenPtr[1].start, len, &ds, &exact)
                == TCL_OK) {
            simple = 1;
            PushLiteral(envPtr, Tcl_DStringValue(&ds),Tcl_DStringLength(&ds));
            Tcl_DStringFree(&ds);
        }
    }

    if (!simple) {
        CompileWord(envPtr, varTokenPtr, interp, parsePtr->numWords-2);
    }

    /*
     * Push the string arg.
     */

    varTokenPtr = TokenAfter(varTokenPtr);
    CompileWord(envPtr, varTokenPtr, interp, parsePtr->numWords-1);

    if (simple) {
        if (exact && !nocase) {
            TclEmitOpcode(INST_STR_EQ, envPtr);
        } else {
            TclEmitInstInt1(INST_STR_MATCH, nocase, envPtr);
        }
    } else {
        /*
         * Pass correct RE compile flags.  We use only Int1 (8-bit), but
         * that handles all the flags we want to pass.
         * Don't use TCL_REG_NOSUB as we may have backrefs.
         */
        int cflags = TCL_REG_ADVANCED | (nocase ? TCL_REG_NOCASE : 0);
        TclEmitInstInt1(INST_REGEXP, cflags, envPtr);
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileReturnCmd --
 *
 *      Procedure called to compile the "return" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "return" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileReturnCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    /*
     * General syntax: [return ?-option value ...? ?result?]
     * An even number of words means an explicit result argument is present.
     */
    int level, code, objc, size, status = TCL_OK;
    int numWords = parsePtr->numWords;
    int explicitResult = (0 == (numWords % 2));
    int numOptionWords = numWords - 1 - explicitResult;
    Tcl_Obj *returnOpts, **objv;
    Tcl_Token *wordTokenPtr = TokenAfter(parsePtr->tokenPtr);
    DefineLineInformation;      /* TIP #280 */

    /*
     * Check for special case which can always be compiled:
     *      return -options <opts> <msg>
     * Unlike the normal [return] compilation, this version does everything at
     * runtime so it can handle arbitrary words and not just literals. Note
     * that if INST_RETURN_STK wasn't already needed for something else
     * ('finally' clause processing) this piece of code would not be present.
     */

    if ((numWords == 4) && (wordTokenPtr->type == TCL_TOKEN_SIMPLE_WORD)
            && (wordTokenPtr[1].size == 8)
            && (strncmp(wordTokenPtr[1].start, "-options", 8) == 0)) {
        Tcl_Token *optsTokenPtr = TokenAfter(wordTokenPtr);
        Tcl_Token *msgTokenPtr = TokenAfter(optsTokenPtr);

        CompileWord(envPtr, optsTokenPtr, interp, 2);
        CompileWord(envPtr, msgTokenPtr,  interp, 3);
        TclEmitOpcode(INST_RETURN_STK, envPtr);
        return TCL_OK;
    }

    /*
     * Allocate some working space.
     */

    objv = (Tcl_Obj **) TclStackAlloc(interp,
            numOptionWords * sizeof(Tcl_Obj *));

    /*
     * Scan through the return options. If any are unknown at compile time,
     * there is no value in bytecompiling. Save the option values known in an
     * objv array for merging into a return options dictionary.
     */

    for (objc = 0; objc < numOptionWords; objc++) {
        objv[objc] = Tcl_NewObj();
        Tcl_IncrRefCount(objv[objc]);
        if (!TclWordKnownAtCompileTime(wordTokenPtr, objv[objc])) {
            objc++;
            status = TCL_ERROR;
            goto cleanup;
        }
        wordTokenPtr = TokenAfter(wordTokenPtr);
    }
    status = TclMergeReturnOptions(interp, objc, objv,
            &returnOpts, &code, &level);
  cleanup:
    while (--objc >= 0) {
        TclDecrRefCount(objv[objc]);
    }
    TclStackFree(interp, objv);
    if (TCL_ERROR == status) {
        /*
         * Something was bogus in the return options. Clear the error message,
         * and report back to the compiler that this must be interpreted at
         * runtime.
         */

        Tcl_ResetResult(interp);
        return TCL_ERROR;
    }

    /*
     * All options are known at compile time, so we're going to bytecompile.
     * Emit instructions to push the result on the stack.
     */

    if (explicitResult) {
         CompileWord(envPtr, wordTokenPtr, interp, numWords-1);
    } else {
        /*
         * No explict result argument, so default result is empty string.
         */

        PushLiteral(envPtr, "", 0);
    }

    /*
     * Check for optimization: When [return] is in a proc, and there's no
     * enclosing [catch], and there are no return options, then the INST_DONE
     * instruction is equivalent, and may be more efficient.
     */

    if (numOptionWords == 0 && envPtr->procPtr != NULL) {
        /*
         * We have default return options and we're in a proc ...
         */

        int index = envPtr->exceptArrayNext - 1;
        int enclosingCatch = 0;

        while (index >= 0) {
            ExceptionRange range = envPtr->exceptArrayPtr[index];
            if ((range.type == CATCH_EXCEPTION_RANGE)
                    && (range.catchOffset == -1)) {
                enclosingCatch = 1;
                break;
            }
            index--;
        }
        if (!enclosingCatch) {
            /*
             * ... and there is no enclosing catch. Issue the maximally
             * efficient exit instruction.
             */

            Tcl_DecrRefCount(returnOpts);
            TclEmitOpcode(INST_DONE, envPtr);
            return TCL_OK;
        }
    }

    /* Optimize [return -level 0 $x]. */
    Tcl_DictObjSize(NULL, returnOpts, &size);
    if (size == 0 && level == 0 && code == TCL_OK) {
        Tcl_DecrRefCount(returnOpts);
        return TCL_OK;
    }

    /*
     * Could not use the optimization, so we push the return options dict, and
     * emit the INST_RETURN_IMM instruction with code and level as operands.
     */

    CompileReturnInternal(envPtr, INST_RETURN_IMM, code, level, returnOpts);
    return TCL_OK;
}

static void
CompileReturnInternal(
    CompileEnv *envPtr,
    unsigned char op,
    int code,
    int level,
    Tcl_Obj *returnOpts)
{
    TclEmitPush(TclAddLiteralObj(envPtr, returnOpts, NULL), envPtr);
    TclEmitInstInt4(op, code, envPtr);
    TclEmitInt4(level, envPtr);
}

void
TclCompileSyntaxError(
    Tcl_Interp *interp,
    CompileEnv *envPtr)
{
    Tcl_Obj *msg = Tcl_GetObjResult(interp);
    int numBytes;
    const char *bytes = TclGetStringFromObj(msg, &numBytes);

    TclEmitPush(TclRegisterNewLiteral(envPtr, bytes, numBytes), envPtr);
    CompileReturnInternal(envPtr, INST_SYNTAX, TCL_ERROR, 0,
            Tcl_GetReturnOptions(interp, TCL_ERROR));
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileSetCmd --
 *
 *      Procedure called to compile the "set" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "set" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileSetCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *varTokenPtr, *valueTokenPtr;
    int isAssignment, isScalar, simpleVarName, localIndex, numWords;
    DefineLineInformation;      /* TIP #280 */

    numWords = parsePtr->numWords;
    if ((numWords != 2) && (numWords != 3)) {
        return TCL_ERROR;
    }
    isAssignment = (numWords == 3);

    /*
     * Decide if we can use a frame slot for the var/array name or if we need
     * to emit code to compute and push the name at runtime. We use a frame
     * slot (entry in the array of local vars) if we are compiling a procedure
     * body and if the name is simple text that does not include namespace
     * qualifiers.
     */

    varTokenPtr = TokenAfter(parsePtr->tokenPtr);
    PushVarName(interp, varTokenPtr, envPtr, TCL_CREATE_VAR,
                &localIndex, &simpleVarName, &isScalar,
                mapPtr->loc[eclIndex].line[1]);

    /*
     * If we are doing an assignment, push the new value.
     */

    if (isAssignment) {
        valueTokenPtr = TokenAfter(varTokenPtr);
        CompileWord(envPtr, valueTokenPtr, interp, 2);
    }

    /*
     * Emit instructions to set/get the variable.
     */

    if (simpleVarName) {
        if (isScalar) {
            if (localIndex < 0) {
                TclEmitOpcode((isAssignment?
                        INST_STORE_SCALAR_STK : INST_LOAD_SCALAR_STK), envPtr);
            } else if (localIndex <= 255) {
                TclEmitInstInt1((isAssignment?
                        INST_STORE_SCALAR1 : INST_LOAD_SCALAR1),
                        localIndex, envPtr);
            } else {
                TclEmitInstInt4((isAssignment?
                        INST_STORE_SCALAR4 : INST_LOAD_SCALAR4),
                        localIndex, envPtr);
            }
        } else {
            if (localIndex < 0) {
                TclEmitOpcode((isAssignment?
                        INST_STORE_ARRAY_STK : INST_LOAD_ARRAY_STK), envPtr);
            } else if (localIndex <= 255) {
                TclEmitInstInt1((isAssignment?
                        INST_STORE_ARRAY1 : INST_LOAD_ARRAY1),
                        localIndex, envPtr);
            } else {
                TclEmitInstInt4((isAssignment?
                        INST_STORE_ARRAY4 : INST_LOAD_ARRAY4),
                        localIndex, envPtr);
            }
        }
    } else {
        TclEmitOpcode((isAssignment? INST_STORE_STK : INST_LOAD_STK), envPtr);
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileStringCmpCmd --
 *
 *      Procedure called to compile the simplest and most common form of the
 *      "string compare" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "string compare"
 *      command at runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileStringCmpCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    DefineLineInformation;      /* TIP #280 */
    Tcl_Token *tokenPtr;

    /*
     * We don't support any flags; the bytecode isn't that sophisticated.
     */

    if (parsePtr->numWords != 3) {
        return TCL_ERROR;
    }

    /*
     * Push the two operands onto the stack and then the test.
     */

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    CompileWord(envPtr, tokenPtr, interp, 1);
    tokenPtr = TokenAfter(tokenPtr);
    CompileWord(envPtr, tokenPtr, interp, 2);
    TclEmitOpcode(INST_STR_CMP, envPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileStringEqualCmd --
 *
 *      Procedure called to compile the simplest and most common form of the
 *      "string equal" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "string equal" command
 *      at runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileStringEqualCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    DefineLineInformation;      /* TIP #280 */
    Tcl_Token *tokenPtr;

    /*
     * We don't support any flags; the bytecode isn't that sophisticated.
     */

    if (parsePtr->numWords != 3) {
        return TCL_ERROR;
    }

    /*
     * Push the two operands onto the stack and then the test.
     */

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    CompileWord(envPtr, tokenPtr, interp, 1);
    tokenPtr = TokenAfter(tokenPtr);
    CompileWord(envPtr, tokenPtr, interp, 2);
    TclEmitOpcode(INST_STR_EQ, envPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileStringIndexCmd --
 *
 *      Procedure called to compile the simplest and most common form of the
 *      "string index" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "string index" command
 *      at runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileStringIndexCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    DefineLineInformation;      /* TIP #280 */
    Tcl_Token *tokenPtr;

    if (parsePtr->numWords != 3) {
        return TCL_ERROR;
    }

    /*
     * Push the two operands onto the stack and then the index operation.
     */

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    CompileWord(envPtr, tokenPtr, interp, 1);
    tokenPtr = TokenAfter(tokenPtr);
    CompileWord(envPtr, tokenPtr, interp, 2);
    TclEmitOpcode(INST_STR_INDEX, envPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileStringMatchCmd --
 *
 *      Procedure called to compile the simplest and most common form of the
 *      "string match" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "string match" command
 *      at runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileStringMatchCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    DefineLineInformation;      /* TIP #280 */
    Tcl_Token *tokenPtr;
    int i, length, exactMatch = 0, nocase = 0;
    const char *str;

    if (parsePtr->numWords < 3 || parsePtr->numWords > 4) {
        return TCL_ERROR;
    }
    tokenPtr = TokenAfter(parsePtr->tokenPtr);

    /*
     * Check if we have a -nocase flag.
     */

    if (parsePtr->numWords == 4) {
        if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
            return TCL_ERROR;
        }
        str = tokenPtr[1].start;
        length = tokenPtr[1].size;
        if ((length <= 1) || strncmp(str, "-nocase", (size_t) length)) {
            /*
             * Fail at run time, not in compilation.
             */

            return TCL_ERROR;
        }
        nocase = 1;
        tokenPtr = TokenAfter(tokenPtr);
    }

    /*
     * Push the strings to match against each other.
     */

    for (i = 0; i < 2; i++) {
        if (tokenPtr->type == TCL_TOKEN_SIMPLE_WORD) {
            str = tokenPtr[1].start;
            length = tokenPtr[1].size;
            if (!nocase && (i == 0)) {
                /*
                 * Trivial matches can be done by 'string equal'. If -nocase
                 * was specified, we can't do this because INST_STR_EQ has no
                 * support for nocase.
                 */

                Tcl_Obj *copy = Tcl_NewStringObj(str, length);

                Tcl_IncrRefCount(copy);
                exactMatch = TclMatchIsTrivial(TclGetString(copy));
                TclDecrRefCount(copy);
            }
            PushLiteral(envPtr, str, length);
        } else {
            envPtr->line = mapPtr->loc[eclIndex].line[i+1+nocase];
            CompileTokens(envPtr, tokenPtr, interp);
        }
        tokenPtr = TokenAfter(tokenPtr);
    }

    /*
     * Push the matcher.
     */

    if (exactMatch) {
        TclEmitOpcode(INST_STR_EQ, envPtr);
    } else {
        TclEmitInstInt1(INST_STR_MATCH, nocase, envPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileStringLenCmd --
 *
 *      Procedure called to compile the simplest and most common form of the
 *      "string length" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "string length"
 *      command at runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileStringLenCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    DefineLineInformation;      /* TIP #280 */
    Tcl_Token *tokenPtr;

    if (parsePtr->numWords != 2) {
        return TCL_ERROR;
    }

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    if (tokenPtr->type == TCL_TOKEN_SIMPLE_WORD) {
        /*
         * Here someone is asking for the length of a static string. Just push
         * the actual character (not byte) length.
         */

        char buf[TCL_INTEGER_SPACE];
        int len = Tcl_NumUtfChars(tokenPtr[1].start, tokenPtr[1].size);

        len = sprintf(buf, "%d", len);
        PushLiteral(envPtr, buf, len);
    } else {
        envPtr->line = mapPtr->loc[eclIndex].line[1];
        CompileTokens(envPtr, tokenPtr, interp);
        TclEmitOpcode(INST_STR_LEN, envPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileSwitchCmd --
 *
 *      Procedure called to compile the "switch" command.
 *
 * Results:
 *      Returns TCL_OK for successful compile, or TCL_ERROR to defer
 *      evaluation to runtime (either when it is too complex to get the
 *      semantics right, or when we know for sure that it is an error but need
 *      the error to happen at the right time).
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "switch" command at
 *      runtime.
 *
 * FIXME:
 *      Stack depths are probably not calculated correctly.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileSwitchCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *tokenPtr;        /* Pointer to tokens in command. */
    int numWords;               /* Number of words in command. */

    Tcl_Token *valueTokenPtr;   /* Token for the value to switch on. */
    enum {Switch_Exact, Switch_Glob, Switch_Regexp} mode;
                                /* What kind of switch are we doing? */

    Tcl_Token *bodyTokenArray;  /* Array of real pattern list items. */
    Tcl_Token **bodyToken;      /* Array of pointers to pattern list items. */
    int *bodyLines;             /* Array of line numbers for body list
                                 * items. */
    int foundDefault;           /* Flag to indicate whether a "default" clause
                                 * is present. */

    JumpFixup *fixupArray;      /* Array of forward-jump fixup records. */
    int *fixupTargetArray;      /* Array of places for fixups to point at. */
    int fixupCount;             /* Number of places to fix up. */
    int contFixIndex;           /* Where the first of the jumps due to a group
                                 * of continuation bodies starts, or -1 if
                                 * there aren't any. */
    int contFixCount;           /* Number of continuation bodies pointing to
                                 * the current (or next) real body. */

    int savedStackDepth = envPtr->currStackDepth;
    int noCase;                 /* Has the -nocase flag been given? */
    int foundMode = 0;          /* Have we seen a mode flag yet? */
    int isListedArms = 0;
    int i, valueIndex;
    DefineLineInformation;      /* TIP #280 */

    /*
     * Only handle the following versions:
     *   switch         ?--? word {pattern body ...}
     *   switch -exact  ?--? word {pattern body ...}
     *   switch -glob   ?--? word {pattern body ...}
     *   switch -regexp ?--? word {pattern body ...}
     *   switch         --   word simpleWordPattern simpleWordBody ...
     *   switch -exact  --   word simpleWordPattern simpleWordBody ...
     *   switch -glob   --   word simpleWordPattern simpleWordBody ...
     *   switch -regexp --   word simpleWordPattern simpleWordBody ...
     * When the mode is -glob, can also handle a -nocase flag.
     *
     * First off, we don't care how the command's word was generated; we're
     * compiling it anyway! So skip it...
     */

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    valueIndex = 1;
    numWords = parsePtr->numWords-1;

    /*
     * Check for options.
     */

    noCase = 0;
    mode = Switch_Exact;
    if (numWords == 2) {
        /*
         * There's just the switch value and the bodies list. In that case, we
         * can skip all option parsing and move on to consider switch values
         * and the body list.
         */

        goto finishedOptionParse;
    }

    /*
     * There must be at least one option, --, because without that there is no
     * way to statically avoid the problems you get from strings-to-be-matched
     * that start with a - (the interpreted code falls apart if it encounters
     * them, so we punt if we *might* encounter them as that is the easiest
     * way of emulating the behaviour).
     */

    for (; numWords>=3 ; tokenPtr=TokenAfter(tokenPtr),numWords--) {
        register unsigned size = tokenPtr[1].size;
        register const char *chrs = tokenPtr[1].start;

        /*
         * We only process literal options, and we assume that -e, -g and -n
         * are unique prefixes of -exact, -glob and -nocase respectively (true
         * at time of writing). Note that -exact and -glob may only be given
         * at most once or we bail out (error case).
         */

        if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD || size < 2) {
            return TCL_ERROR;
        }

        if ((size <= 6) && !memcmp(chrs, "-exact", size)) {
            if (foundMode) {
                return TCL_ERROR;
            }
            mode = Switch_Exact;
            foundMode = 1;
            valueIndex++;
            continue;
        } else if ((size <= 5) && !memcmp(chrs, "-glob", size)) {
            if (foundMode) {
                return TCL_ERROR;
            }
            mode = Switch_Glob;
            foundMode = 1;
            valueIndex++;
            continue;
        } else if ((size <= 7) && !memcmp(chrs, "-regexp", size)) {
            if (foundMode) {
                return TCL_ERROR;
            }
            mode = Switch_Regexp;
            foundMode = 1;
            valueIndex++;
            continue;
        } else if ((size <= 7) && !memcmp(chrs, "-nocase", size)) {
            noCase = 1;
            valueIndex++;
            continue;
        } else if ((size == 2) && !memcmp(chrs, "--", 2)) {
            valueIndex++;
            break;
        }

        /*
         * The switch command has many flags we cannot compile at all (e.g.
         * all the RE-related ones) which we must have encountered. Either
         * that or we have run off the end. The action here is the same: punt
         * to interpreted version.
         */

        return TCL_ERROR;
    }
    if (numWords < 3) {
        return TCL_ERROR;
    }
    tokenPtr = TokenAfter(tokenPtr);
    numWords--;
    if (noCase && (mode == Switch_Exact)) {
        /*
         * Can't compile this case; no opcode for case-insensitive equality!
         */

        return TCL_ERROR;
    }

    /*
     * The value to test against is going to always get pushed on the stack.
     * But not yet; we need to verify that the rest of the command is
     * compilable too.
     */

  finishedOptionParse:
    valueTokenPtr = tokenPtr;
    /* For valueIndex, see previous loop. */
    tokenPtr = TokenAfter(tokenPtr);
    numWords--;

    /*
     * Build an array of tokens for the matcher terms and script bodies. Note
     * that in the case of the quoted bodies, this is tricky as we cannot use
     * copies of the string from the input token for the generated tokens (it
     * causes a crash during exception handling). When multiple tokens are
     * available at this point, this is pretty easy.
     */

    if (numWords == 1) {
        Tcl_DString bodyList;
        const char **argv = NULL, *tokenStartPtr, *p;
        int bline;              /* TIP #280: line of the pattern/action list,
                                 * and start of list for when tracking the
                                 * location. This list comes immediately after
                                 * the value we switch on. */
        int isTokenBraced;

        /*
         * Test that we've got a suitable body list as a simple (i.e. braced)
         * word, and that the elements of the body are simple words too. This
         * is really rather nasty indeed.
         */

        if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
            return TCL_ERROR;
        }

        Tcl_DStringInit(&bodyList);
        Tcl_DStringAppend(&bodyList, tokenPtr[1].start, tokenPtr[1].size);
        if (Tcl_SplitList(NULL, Tcl_DStringValue(&bodyList), &numWords,
                &argv) != TCL_OK) {
            Tcl_DStringFree(&bodyList);
            return TCL_ERROR;
        }
        Tcl_DStringFree(&bodyList);

        /*
         * Now we know what the switch arms are, we've got to see whether we
         * can synthesize tokens for the arms. First check whether we've got a
         * valid number of arms since we can do that now.
         */

        if (numWords == 0 || numWords % 2) {
            ckfree((char *) argv);
            return TCL_ERROR;
        }

        isListedArms = 1;
        bodyTokenArray = (Tcl_Token *) ckalloc(sizeof(Tcl_Token) * numWords);
        bodyToken = (Tcl_Token **) ckalloc(sizeof(Tcl_Token *) * numWords);
        bodyLines = (int *) ckalloc(sizeof(int) * numWords);

        /*
         * Locate the start of the arms within the overall word.
         */

        bline = mapPtr->loc[eclIndex].line[valueIndex+1];
        p = tokenStartPtr = tokenPtr[1].start;
        while (isspace(UCHAR(*tokenStartPtr))) {
            tokenStartPtr++;
        }
        if (*tokenStartPtr == '{') {
            tokenStartPtr++;
            isTokenBraced = 1;
        } else {
            isTokenBraced = 0;
        }

        /*
         * TIP #280: Count lines within the literal list.
         */

        for (i=0 ; i<numWords ; i++) {
            bodyTokenArray[i].type = TCL_TOKEN_TEXT;
            bodyTokenArray[i].start = tokenStartPtr;
            bodyTokenArray[i].size = strlen(argv[i]);
            bodyTokenArray[i].numComponents = 0;
            bodyToken[i] = bodyTokenArray+i;
            tokenStartPtr += bodyTokenArray[i].size;

            /*
             * Test to see if we have guessed the end of the word correctly;
             * if not, we can't feed the real string to the sub-compilation
             * engine, and we're then stuck and so have to punt out to doing
             * everything at runtime.
             */

            if ((isTokenBraced && *(tokenStartPtr++) != '}') ||
                    (tokenStartPtr < tokenPtr[1].start+tokenPtr[1].size
                    && !isspace(UCHAR(*tokenStartPtr)))) {
                ckfree((char *) argv);
                ckfree((char *) bodyToken);
                ckfree((char *) bodyTokenArray);
                ckfree((char *) bodyLines);
                return TCL_ERROR;
            }

            /*
             * TIP #280: Now determine the line the list element starts on
             * (there is no need to do it earlier, due to the possibility of
             * aborting, see above).
             */

            TclAdvanceLines(&bline, p, bodyTokenArray[i].start);
            bodyLines[i] = bline;
            p = bodyTokenArray[i].start;

            while (isspace(UCHAR(*tokenStartPtr))) {
                tokenStartPtr++;
                if (tokenStartPtr >= tokenPtr[1].start+tokenPtr[1].size) {
                    break;
                }
            }
            if (*tokenStartPtr == '{') {
                tokenStartPtr++;
                isTokenBraced = 1;
            } else {
                isTokenBraced = 0;
            }
        }
        ckfree((char *) argv);

        /*
         * Check that we've parsed everything we thought we were going to
         * parse. If not, something odd is going on (I believe it is possible
         * to defeat the code above) and we should bail out.
         */

        if (tokenStartPtr != tokenPtr[1].start+tokenPtr[1].size) {
            ckfree((char *) bodyToken);
            ckfree((char *) bodyTokenArray);
            ckfree((char *) bodyLines);
            return TCL_ERROR;
        }

    } else if (numWords % 2 || numWords == 0) {
        /*
         * Odd number of words (>1) available, or no words at all available.
         * Both are error cases, so punt and let the interpreted-version
         * generate the error message. Note that the second case probably
         * should get caught earlier, but it's easy to check here again anyway
         * because it'd cause a nasty crash otherwise.
         */

        return TCL_ERROR;
    } else {
        /*
         * Multi-word definition of patterns & actions.
         */

        bodyToken = (Tcl_Token **) ckalloc(sizeof(Tcl_Token *) * numWords);
        bodyLines = (int *) ckalloc(sizeof(int) * numWords);
        bodyTokenArray = NULL;
        for (i=0 ; i<numWords ; i++) {
            /*
             * We only handle the very simplest case. Anything more complex is
             * a good reason to go to the interpreted case anyway due to
             * traces, etc.
             */

            if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD ||
                    tokenPtr->numComponents != 1) {
                ckfree((char *) bodyToken);
                ckfree((char *) bodyLines);
                return TCL_ERROR;
            }
            bodyToken[i] = tokenPtr+1;

            /*
             * TIP #280: Copy line information from regular cmd info.
             */

            bodyLines[i] = mapPtr->loc[eclIndex].line[valueIndex+1+i];
            tokenPtr = TokenAfter(tokenPtr);
        }
    }

    /*
     * Fall back to interpreted if the last body is a continuation (it's
     * illegal, but this makes the error happen at the right time).
     */

    if (bodyToken[numWords-1]->size == 1 &&
            bodyToken[numWords-1]->start[0] == '-') {
        ckfree((char *) bodyToken);
        ckfree((char *) bodyLines);
        if (bodyTokenArray != NULL) {
            ckfree((char *) bodyTokenArray);
        }
        return TCL_ERROR;
    }

    /*
     * Now we commit to generating code; the parsing stage per se is done.
     * First, we push the value we're matching against on the stack.
     */

    envPtr->line = mapPtr->loc[eclIndex].line[valueIndex];
    CompileTokens(envPtr, valueTokenPtr, interp);

    /*
     * Check if we can generate a jump table, since if so that's faster than
     * doing an explicit compare with each body. Note that we're definitely
     * over-conservative with determining whether we can do the jump table,
     * but it handles the most common case well enough.
     */

    if (isListedArms && mode == Switch_Exact && !noCase) {
        JumptableInfo *jtPtr;
        int infoIndex, isNew, *finalFixups, numRealBodies = 0, jumpLocation;
        int mustGenerate, jumpToDefault;
        Tcl_DString buffer;
        Tcl_HashEntry *hPtr;

        /*
         * Compile the switch by using a jump table, which is basically a
         * hashtable that maps from literal values to match against to the
         * offset (relative to the INST_JUMP_TABLE instruction) to jump to.
         * The jump table itself is independent of any invokation of the
         * bytecode, and as such is stored in an auxData block.
         *
         * Start by allocating the jump table itself, plus some workspace.
         */

        jtPtr = (JumptableInfo *) ckalloc(sizeof(JumptableInfo));
        Tcl_InitHashTable(&jtPtr->hashTable, TCL_STRING_KEYS);
        infoIndex = TclCreateAuxData(jtPtr, &tclJumptableInfoType, envPtr);
        finalFixups = (int *) ckalloc(sizeof(int) * (numWords/2));
        foundDefault = 0;
        mustGenerate = 1;

        /*
         * Next, issue the instruction to do the jump, together with what we
         * want to do if things do not work out (jump to either the default
         * clause or the "default" default, which just sets the result to
         * empty). Note that we will come back and rewrite the jump's offset
         * parameter when we know what it should be, and that all jumps we
         * issue are of the wide kind because that makes the code much easier
         * to debug!
         */

        jumpLocation = CurrentOffset(envPtr);
        TclEmitInstInt4(INST_JUMP_TABLE, infoIndex, envPtr);
        jumpToDefault = CurrentOffset(envPtr);
        TclEmitInstInt4(INST_JUMP4, 0, envPtr);

        for (i=0 ; i<numWords ; i+=2) {
            /*
             * For each arm, we must first work out what to do with the match
             * term.
             */

            if (i!=numWords-2 || bodyToken[numWords-2]->size != 7 ||
                    memcmp(bodyToken[numWords-2]->start, "default", 7)) {
                /*
                 * This is not a default clause, so insert the current
                 * location as a target in the jump table (assuming it isn't
                 * already there, which would indicate that this clause is
                 * probably masked by an earlier one). Note that we use a
                 * Tcl_DString here simply because the hash API does not let
                 * us specify the string length.
                 */

                Tcl_DStringInit(&buffer);
                Tcl_DStringAppend(&buffer, bodyToken[i]->start,
                        bodyToken[i]->size);
                hPtr = Tcl_CreateHashEntry(&jtPtr->hashTable,
                        Tcl_DStringValue(&buffer), &isNew);
                if (isNew) {
                    /*
                     * First time we've encountered this match clause, so it
                     * must point to here.
                     */

                    Tcl_SetHashValue(hPtr, (ClientData)
                            (CurrentOffset(envPtr) - jumpLocation));
                }
                Tcl_DStringFree(&buffer);
            } else {
                /*
                 * This is a default clause, so patch up the fallthrough from
                 * the INST_JUMP_TABLE instruction to here.
                 */

                foundDefault = 1;
                isNew = 1;
                TclStoreInt4AtPtr(CurrentOffset(envPtr)-jumpToDefault,
                        envPtr->codeStart+jumpToDefault+1);
            }

            /*
             * Now, for each arm we must deal with the body of the clause.
             *
             * If this is a continuation body (never true of a final clause,
             * whether default or not) we're done because the next jump target
             * will also point here, so we advance to the next clause.
             */

            if (bodyToken[i+1]->size == 1 && bodyToken[i+1]->start[0] == '-') {
                mustGenerate = 1;
                continue;
            }

            /*
             * Also skip this arm if its only match clause is masked. (We
             * could probably be more aggressive about this, but that would be
             * much more difficult to get right.)
             */

            if (!isNew && !mustGenerate) {
                continue;
            }
            mustGenerate = 0;

            /*
             * Compile the body of the arm.
             */

            envPtr->line = bodyLines[i+1];      /* TIP #280 */
            TclCompileCmdWord(interp, bodyToken[i+1], 1, envPtr);

            /*
             * Compile a jump in to the end of the command if this body is
             * anything other than a user-supplied default arm (to either skip
             * over the remaining bodies or the code that generates an empty
             * result).
             */

            if (i+2 < numWords || !foundDefault) {
                finalFixups[numRealBodies++] = CurrentOffset(envPtr);

                /*
                 * Easier by far to issue this jump as a fixed-width jump.
                 * Otherwise we'd need to do a lot more (and more awkward)
                 * rewriting when we fixed this all up.
                 */

                TclEmitInstInt4(INST_JUMP4, 0, envPtr);
            }
        }

        /*
         * We're at the end. If we've not already done so through the
         * processing of a user-supplied default clause, add in a "default"
         * default clause now.
         */

        if (!foundDefault) {
            TclStoreInt4AtPtr(CurrentOffset(envPtr)-jumpToDefault,
                    envPtr->codeStart+jumpToDefault+1);
            PushLiteral(envPtr, "", 0);
        }

        /*
         * No more instructions to be issued; everything that needs to jump to
         * the end of the command is fixed up at this point.
         */

        for (i=0 ; i<numRealBodies ; i++) {
            TclStoreInt4AtPtr(CurrentOffset(envPtr)-finalFixups[i],
                    envPtr->codeStart+finalFixups[i]+1);
        }

        /*
         * Clean up all our temporary space and return.
         */

        ckfree((char *) finalFixups);
        ckfree((char *) bodyToken);
        ckfree((char *) bodyLines);
        if (bodyTokenArray != NULL) {
            ckfree((char *) bodyTokenArray);
        }
        return TCL_OK;
    }

    /*
     * Generate a test for each arm.
     */

    contFixIndex = -1;
    contFixCount = 0;
    fixupArray = (JumpFixup *) ckalloc(sizeof(JumpFixup) * numWords);
    fixupTargetArray = (int *) ckalloc(sizeof(int) * numWords);
    memset(fixupTargetArray, 0, numWords * sizeof(int));
    fixupCount = 0;
    foundDefault = 0;
    for (i=0 ; i<numWords ; i+=2) {
        int nextArmFixupIndex = -1;

        envPtr->currStackDepth = savedStackDepth + 1;
        if (i!=numWords-2 || bodyToken[numWords-2]->size != 7 ||
                memcmp(bodyToken[numWords-2]->start, "default", 7)) {
            /*
             * Generate the test for the arm.
             */

            switch (mode) {
            case Switch_Exact:
                TclEmitOpcode(INST_DUP, envPtr);
                TclCompileTokens(interp, bodyToken[i], 1, envPtr);
                TclEmitOpcode(INST_STR_EQ, envPtr);
                break;
            case Switch_Glob:
                TclCompileTokens(interp, bodyToken[i], 1, envPtr);
                TclEmitInstInt4(INST_OVER, 1, envPtr);
                TclEmitInstInt1(INST_STR_MATCH, noCase, envPtr);
                break;
            case Switch_Regexp: {
                int simple = 0, exact = 0;

                /*
                 * Keep in sync with TclCompileRegexpCmd.
                 */

                if (bodyToken[i]->type == TCL_TOKEN_TEXT) {
                    Tcl_DString ds;

                    if (bodyToken[i]->size == 0) {
                        /*
                         * The semantics of regexps are that they always match
                         * when the RE == "".
                         */

                        PushLiteral(envPtr, "1", 1);
                        break;
                    }

                    /*
                     * Attempt to convert pattern to glob. If successful, push
                     * the converted pattern.
                     */

                    if (TclReToGlob(NULL, bodyToken[i]->start,
                            bodyToken[i]->size, &ds, &exact) == TCL_OK) {
                        simple = 1;
                        PushLiteral(envPtr, Tcl_DStringValue(&ds),
                                Tcl_DStringLength(&ds));
                        Tcl_DStringFree(&ds);
                    }
                }
                if (!simple) {
                    TclCompileTokens(interp, bodyToken[i], 1, envPtr);
                }

                TclEmitInstInt4(INST_OVER, 1, envPtr);
                if (simple) {
                    if (exact && !noCase) {
                        TclEmitOpcode(INST_STR_EQ, envPtr);
                    } else {
                        TclEmitInstInt1(INST_STR_MATCH, noCase, envPtr);
                    }
                } else {
                    /*
                     * Pass correct RE compile flags. We use only Int1
                     * (8-bit), but that handles all the flags we want to
                     * pass. Don't use TCL_REG_NOSUB as we may have backrefs
                     * or capture vars.
                     */

                    int cflags = TCL_REG_ADVANCED
                            | (noCase ? TCL_REG_NOCASE : 0);

                    TclEmitInstInt1(INST_REGEXP, cflags, envPtr);
                }
                break;
            }
            default:
                Tcl_Panic("unknown switch mode: %d", mode);
            }

            /*
             * In a fall-through case, we will jump on _true_ to the place
             * where the body starts (generated later, with guarantee of this
             * ensured earlier; the final body is never a fall-through).
             */

            if (bodyToken[i+1]->size==1 && bodyToken[i+1]->start[0]=='-') {
                if (contFixIndex == -1) {
                    contFixIndex = fixupCount;
                    contFixCount = 0;
                }
                TclEmitForwardJump(envPtr, TCL_TRUE_JUMP,
                        fixupArray+contFixIndex+contFixCount);
                fixupCount++;
                contFixCount++;
                continue;
            }

            TclEmitForwardJump(envPtr, TCL_FALSE_JUMP, fixupArray+fixupCount);
            nextArmFixupIndex = fixupCount;
            fixupCount++;
        } else {
            /*
             * Got a default clause; set a flag to inhibit the generation of
             * the jump after the body and the cleanup of the intermediate
             * value that we are switching against.
             *
             * Note that default clauses (which are always terminal clauses)
             * cannot be fall-through clauses as well, since the last clause
             * is never a fall-through clause (which we have already
             * verified).
             */

            foundDefault = 1;
        }

        /*
         * Generate the body for the arm. This is guaranteed not to be a
         * fall-through case, but it might have preceding fall-through cases,
         * so we must process those first.
         */

        if (contFixIndex != -1) {
            int j;

            for (j=0 ; j<contFixCount ; j++) {
                fixupTargetArray[contFixIndex+j] = CurrentOffset(envPtr);
            }
            contFixIndex = -1;
        }

        /*
         * Now do the actual compilation. Note that we do not use CompileBody
         * because we may have synthesized the tokens in a non-standard
         * pattern.
         */

        TclEmitOpcode(INST_POP, envPtr);
        envPtr->currStackDepth = savedStackDepth + 1;
        envPtr->line = bodyLines[i+1];          /* TIP #280 */
        TclCompileCmdWord(interp, bodyToken[i+1], 1, envPtr);

        if (!foundDefault) {
            TclEmitForwardJump(envPtr, TCL_UNCONDITIONAL_JUMP,
                    fixupArray+fixupCount);
            fixupCount++;
            fixupTargetArray[nextArmFixupIndex] = CurrentOffset(envPtr);
        }
    }

    /*
     * Clean up all our temporary space and return.
     */

    ckfree((char *) bodyToken);
    ckfree((char *) bodyLines);
    if (bodyTokenArray != NULL) {
        ckfree((char *) bodyTokenArray);
    }

    /*
     * Discard the value we are matching against unless we've had a default
     * clause (in which case it will already be gone due to the code at the
     * start of processing an arm, guaranteed) and make the result of the
     * command an empty string.
     */

    if (!foundDefault) {
        TclEmitOpcode(INST_POP, envPtr);
        PushLiteral(envPtr, "", 0);
    }

    /*
     * Do jump fixups for arms that were executed. First, fill in the jumps of
     * all jumps that don't point elsewhere to point to here.
     */

    for (i=0 ; i<fixupCount ; i++) {
        if (fixupTargetArray[i] == 0) {
            fixupTargetArray[i] = envPtr->codeNext-envPtr->codeStart;
        }
    }

    /*
     * Now scan backwards over all the jumps (all of which are forward jumps)
     * doing each one. When we do one and there is a size changes, we must
     * scan back over all the previous ones and see if they need adjusting
     * before proceeding with further jump fixups (the interleaved nature of
     * all the jumps makes this impossible to do without nested loops).
     */

    for (i=fixupCount-1 ; i>=0 ; i--) {
        if (TclFixupForwardJump(envPtr, &fixupArray[i],
                fixupTargetArray[i] - fixupArray[i].codeOffset, 127)) {
            int j;

            for (j=i-1 ; j>=0 ; j--) {
                if (fixupTargetArray[j] > fixupArray[i].codeOffset) {
                    fixupTargetArray[j] += 3;
                }
            }
        }
    }
    ckfree((char *) fixupArray);
    ckfree((char *) fixupTargetArray);

    envPtr->currStackDepth = savedStackDepth + 1;
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * DupJumptableInfo, FreeJumptableInfo --
 *
 *      Functions to duplicate, release and print a jump-table created for use
 *      with the INST_JUMP_TABLE instruction.
 *
 * Results:
 *      DupJumptableInfo: a copy of the jump-table
 *      FreeJumptableInfo: none
 *      PrintJumptableInfo: none
 *
 * Side effects:
 *      DupJumptableInfo: allocates memory
 *      FreeJumptableInfo: releases memory
 *      PrintJumptableInfo: none
 *
 *----------------------------------------------------------------------
 */

static ClientData
DupJumptableInfo(
    ClientData clientData)
{
    JumptableInfo *jtPtr = clientData;
    JumptableInfo *newJtPtr = (JumptableInfo *)
            ckalloc(sizeof(JumptableInfo));
    Tcl_HashEntry *hPtr, *newHPtr;
    Tcl_HashSearch search;
    int isNew;

    Tcl_InitHashTable(&newJtPtr->hashTable, TCL_STRING_KEYS);
    hPtr = Tcl_FirstHashEntry(&jtPtr->hashTable, &search);
    while (hPtr != NULL) {
        newHPtr = Tcl_CreateHashEntry(&newJtPtr->hashTable,
                Tcl_GetHashKey(&jtPtr->hashTable, hPtr), &isNew);
        Tcl_SetHashValue(newHPtr, Tcl_GetHashValue(hPtr));
    }
    return newJtPtr;
}

static void
FreeJumptableInfo(
    ClientData clientData)
{
    JumptableInfo *jtPtr = clientData;

    Tcl_DeleteHashTable(&jtPtr->hashTable);
    ckfree((char *) jtPtr);
}

static void
PrintJumptableInfo(
    ClientData clientData,
    Tcl_Obj *appendObj,
    ByteCode *codePtr,
    unsigned int pcOffset)
{
    register JumptableInfo *jtPtr = clientData;
    Tcl_HashEntry *hPtr;
    Tcl_HashSearch search;
    const char *keyPtr;
    int offset, i = 0;

    hPtr = Tcl_FirstHashEntry(&jtPtr->hashTable, &search);
    for (; hPtr ; hPtr = Tcl_NextHashEntry(&search)) {
        keyPtr = Tcl_GetHashKey(&jtPtr->hashTable, hPtr);
        offset = PTR2INT(Tcl_GetHashValue(hPtr));

        if (i++) {
            Tcl_AppendToObj(appendObj, ", ", -1);
            if (i%4==0) {
                Tcl_AppendToObj(appendObj, "\n\t\t", -1);
            }
        }
        Tcl_AppendPrintfToObj(appendObj, "\"%s\"->pc %d",
                keyPtr, pcOffset + offset);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileWhileCmd --
 *
 *      Procedure called to compile the "while" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "while" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileWhileCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *testTokenPtr, *bodyTokenPtr;
    JumpFixup jumpEvalCondFixup;
    int testCodeOffset, bodyCodeOffset, jumpDist, range, code, boolVal;
    int savedStackDepth = envPtr->currStackDepth;
    int loopMayEnd = 1;         /* This is set to 0 if it is recognized as an
                                 * infinite loop. */
    Tcl_Obj *boolObj;
    DefineLineInformation;      /* TIP #280 */

    if (parsePtr->numWords != 3) {
        return TCL_ERROR;
    }

    /*
     * If the test expression requires substitutions, don't compile the while
     * command inline. E.g., the expression might cause the loop to never
     * execute or execute forever, as in "while "$x < 5" {}".
     *
     * Bail out also if the body expression requires substitutions in order to
     * insure correct behaviour [Bug 219166]
     */

    testTokenPtr = TokenAfter(parsePtr->tokenPtr);
    bodyTokenPtr = TokenAfter(testTokenPtr);

    if ((testTokenPtr->type != TCL_TOKEN_SIMPLE_WORD)
            || (bodyTokenPtr->type != TCL_TOKEN_SIMPLE_WORD)) {
        return TCL_ERROR;
    }

    /*
     * Find out if the condition is a constant.
     */

    boolObj = Tcl_NewStringObj(testTokenPtr[1].start, testTokenPtr[1].size);
    Tcl_IncrRefCount(boolObj);
    code = Tcl_GetBooleanFromObj(NULL, boolObj, &boolVal);
    TclDecrRefCount(boolObj);
    if (code == TCL_OK) {
        if (boolVal) {
            /*
             * It is an infinite loop; flag it so that we generate a more
             * efficient body.
             */

            loopMayEnd = 0;
        } else {
            /*
             * This is an empty loop: "while 0 {...}" or such. Compile no
             * bytecodes.
             */

            goto pushResult;
        }
    }

    /*
     * Create a ExceptionRange record for the loop body. This is used to
     * implement break and continue.
     */

    range = DeclareExceptionRange(envPtr, LOOP_EXCEPTION_RANGE);

    /*
     * Jump to the evaluation of the condition. This code uses the "loop
     * rotation" optimisation (which eliminates one branch from the loop).
     * "while cond body" produces then:
     *       goto A
     *    B: body                : bodyCodeOffset
     *    A: cond -> result      : testCodeOffset, continueOffset
     *       if (result) goto B
     *
     * The infinite loop "while 1 body" produces:
     *    B: body                : all three offsets here
     *       goto B
     */

    if (loopMayEnd) {
        TclEmitForwardJump(envPtr, TCL_UNCONDITIONAL_JUMP, &jumpEvalCondFixup);
        testCodeOffset = 0;     /* Avoid compiler warning. */
    } else {
        /*
         * Make sure that the first command in the body is preceded by an
         * INST_START_CMD, and hence counted properly. [Bug 1752146]
         */

        envPtr->atCmdStart = 0;
        testCodeOffset = CurrentOffset(envPtr);
    }

    /*
     * Compile the loop body.
     */

    envPtr->line = mapPtr->loc[eclIndex].line[2];
    bodyCodeOffset = ExceptionRangeStarts(envPtr, range);
    CompileBody(envPtr, bodyTokenPtr, interp);
    ExceptionRangeEnds(envPtr, range);
    envPtr->currStackDepth = savedStackDepth + 1;
    TclEmitOpcode(INST_POP, envPtr);

    /*
     * Compile the test expression then emit the conditional jump that
     * terminates the while. We already know it's a simple word.
     */

    if (loopMayEnd) {
        testCodeOffset = CurrentOffset(envPtr);
        jumpDist = testCodeOffset - jumpEvalCondFixup.codeOffset;
        if (TclFixupForwardJump(envPtr, &jumpEvalCondFixup, jumpDist, 127)) {
            bodyCodeOffset += 3;
            testCodeOffset += 3;
        }
        envPtr->currStackDepth = savedStackDepth;
        envPtr->line = mapPtr->loc[eclIndex].line[1];
        TclCompileExprWords(interp, testTokenPtr, 1, envPtr);
        envPtr->currStackDepth = savedStackDepth + 1;

        jumpDist = CurrentOffset(envPtr) - bodyCodeOffset;
        if (jumpDist > 127) {
            TclEmitInstInt4(INST_JUMP_TRUE4, -jumpDist, envPtr);
        } else {
            TclEmitInstInt1(INST_JUMP_TRUE1, -jumpDist, envPtr);
        }
    } else {
        jumpDist = CurrentOffset(envPtr) - bodyCodeOffset;
        if (jumpDist > 127) {
            TclEmitInstInt4(INST_JUMP4, -jumpDist, envPtr);
        } else {
            TclEmitInstInt1(INST_JUMP1, -jumpDist, envPtr);
        }
    }

    /*
     * Set the loop's body, continue and break offsets.
     */

    envPtr->exceptArrayPtr[range].continueOffset = testCodeOffset;
    envPtr->exceptArrayPtr[range].codeOffset = bodyCodeOffset;
    ExceptionRangeTarget(envPtr, range, breakOffset);

    /*
     * The while command's result is an empty string.
     */

  pushResult:
    envPtr->currStackDepth = savedStackDepth;
    PushLiteral(envPtr, "", 0);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * PushVarName --
 *
 *      Procedure used in the compiling where pushing a variable name is
 *      necessary (append, lappend, set).
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "set" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

static int
PushVarName(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Token *varTokenPtr,     /* Points to a variable token. */
    CompileEnv *envPtr,         /* Holds resulting instructions. */
    int flags,                  /* TCL_CREATE_VAR or TCL_NO_LARGE_INDEX. */
    int *localIndexPtr,         /* Must not be NULL. */
    int *simpleVarNamePtr,      /* Must not be NULL. */
    int *isScalarPtr,           /* Must not be NULL. */
    int line)                   /* Line the token starts on. */
{
    register const char *p;
    const char *name, *elName;
    register int i, n;
    Tcl_Token *elemTokenPtr = NULL;
    int nameChars, elNameChars, simpleVarName, localIndex;
    int elemTokenCount = 0, allocedTokens = 0, removedParen = 0;

    /*
     * Decide if we can use a frame slot for the var/array name or if we need
     * to emit code to compute and push the name at runtime. We use a frame
     * slot (entry in the array of local vars) if we are compiling a procedure
     * body and if the name is simple text that does not include namespace
     * qualifiers.
     */

    simpleVarName = 0;
    name = elName = NULL;
    nameChars = elNameChars = 0;
    localIndex = -1;

    /*
     * Check not only that the type is TCL_TOKEN_SIMPLE_WORD, but whether
     * curly braces surround the variable name. This really matters for array
     * elements to handle things like
     *    set {x($foo)} 5
     * which raises an undefined var error if we are not careful here.
     */

    if ((varTokenPtr->type == TCL_TOKEN_SIMPLE_WORD) &&
            (varTokenPtr->start[0] != '{')) {
        /*
         * A simple variable name. Divide it up into "name" and "elName"
         * strings. If it is not a local variable, look it up at runtime.
         */

        simpleVarName = 1;

        name = varTokenPtr[1].start;
        nameChars = varTokenPtr[1].size;
        if (name[nameChars-1] == ')') {
            /*
             * last char is ')' => potential array reference.
             */

            for (i=0,p=name ; i<nameChars ; i++,p++) {
                if (*p == '(') {
                    elName = p + 1;
                    elNameChars = nameChars - i - 2;
                    nameChars = i;
                    break;
                }
            }

            if ((elName != NULL) && elNameChars) {
                /*
                 * An array element, the element name is a simple string:
                 * assemble the corresponding token.
                 */

                elemTokenPtr = (Tcl_Token *) TclStackAlloc(interp,
                        sizeof(Tcl_Token));
                allocedTokens = 1;
                elemTokenPtr->type = TCL_TOKEN_TEXT;
                elemTokenPtr->start = elName;
                elemTokenPtr->size = elNameChars;
                elemTokenPtr->numComponents = 0;
                elemTokenCount = 1;
            }
        }
    } else if (((n = varTokenPtr->numComponents) > 1)
            && (varTokenPtr[1].type == TCL_TOKEN_TEXT)
            && (varTokenPtr[n].type == TCL_TOKEN_TEXT)
            && (varTokenPtr[n].start[varTokenPtr[n].size - 1] == ')')) {

        /*
         * Check for parentheses inside first token.
         */

        simpleVarName = 0;
        for (i = 0, p = varTokenPtr[1].start;
                i < varTokenPtr[1].size; i++, p++) {
            if (*p == '(') {
                simpleVarName = 1;
                break;
            }
        }
        if (simpleVarName) {
            int remainingChars;

            /*
             * Check the last token: if it is just ')', do not count it.
             * Otherwise, remove the ')' and flag so that it is restored at
             * the end.
             */

            if (varTokenPtr[n].size == 1) {
                --n;
            } else {
                --varTokenPtr[n].size;
                removedParen = n;
            }

            name = varTokenPtr[1].start;
            nameChars = p - varTokenPtr[1].start;
            elName = p + 1;
            remainingChars = (varTokenPtr[2].start - p) - 1;
            elNameChars = (varTokenPtr[n].start - p) + varTokenPtr[n].size - 2;

            if (remainingChars) {
                /*
                 * Make a first token with the extra characters in the first
                 * token.
                 */

                elemTokenPtr = (Tcl_Token *) TclStackAlloc(interp,
                        n * sizeof(Tcl_Token));
                allocedTokens = 1;
                elemTokenPtr->type = TCL_TOKEN_TEXT;
                elemTokenPtr->start = elName;
                elemTokenPtr->size = remainingChars;
                elemTokenPtr->numComponents = 0;
                elemTokenCount = n;

                /*
                 * Copy the remaining tokens.
                 */

                memcpy(elemTokenPtr+1, varTokenPtr+2,
                        (n-1) * sizeof(Tcl_Token));
            } else {
                /*
                 * Use the already available tokens.
                 */

                elemTokenPtr = &varTokenPtr[2];
                elemTokenCount = n - 1;
            }
        }
    }

    if (simpleVarName) {
        /*
         * See whether name has any namespace separators (::'s).
         */

        int hasNsQualifiers = 0;
        for (i = 0, p = name;  i < nameChars;  i++, p++) {
            if ((*p == ':') && ((i+1) < nameChars) && (*(p+1) == ':')) {
                hasNsQualifiers = 1;
                break;
            }
        }

        /*
         * Look up the var name's index in the array of local vars in the proc
         * frame. If retrieving the var's value and it doesn't already exist,
         * push its name and look it up at runtime.
         */

        if ((envPtr->procPtr != NULL) && !hasNsQualifiers) {
            localIndex = TclFindCompiledLocal(name, nameChars,
                    /*create*/ flags & TCL_CREATE_VAR,
                    envPtr->procPtr);
            if ((flags & TCL_NO_LARGE_INDEX) && (localIndex > 255)) {
                /*
                 * We'll push the name.
                 */

                localIndex = -1;
            }
        }
        if (localIndex < 0) {
            PushLiteral(envPtr, name, nameChars);
        }

        /*
         * Compile the element script, if any.
         */

        if (elName != NULL) {
            if (elNameChars) {
                envPtr->line = line;
                TclCompileTokens(interp, elemTokenPtr, elemTokenCount, envPtr);
            } else {
                PushLiteral(envPtr, "", 0);
            }
        }
    } else {
        /*
         * The var name isn't simple: compile and push it.
         */

        envPtr->line = line;
        CompileTokens(envPtr, varTokenPtr, interp);
    }

    if (removedParen) {
        ++varTokenPtr[removedParen].size;
    }
    if (allocedTokens) {
        TclStackFree(interp, elemTokenPtr);
    }
    *localIndexPtr = localIndex;
    *simpleVarNamePtr = simpleVarName;
    *isScalarPtr = (elName == NULL);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * CompileUnaryOpCmd --
 *
 *      Utility routine to compile the unary operator commands.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the compiled command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

static int
CompileUnaryOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    int instruction,
    CompileEnv *envPtr)
{
    Tcl_Token *tokenPtr;
    DefineLineInformation;      /* TIP #280 */

    if (parsePtr->numWords != 2) {
        return TCL_ERROR;
    }
    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    CompileWord(envPtr, tokenPtr, interp, 1);
    TclEmitOpcode(instruction, envPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * CompileAssociativeBinaryOpCmd --
 *
 *      Utility routine to compile the binary operator commands that accept an
 *      arbitrary number of arguments, and that are associative operations.
 *      Because of the associativity, we may combine operations from right to
 *      left, saving us any effort of re-ordering the arguments on the stack
 *      after substitutions are completed.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the compiled command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

static int
CompileAssociativeBinaryOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    const char *identity,
    int instruction,
    CompileEnv *envPtr)
{
    Tcl_Token *tokenPtr = parsePtr->tokenPtr;
    DefineLineInformation;      /* TIP #280 */
    int words;

    for (words=1 ; words<parsePtr->numWords ; words++) {
        tokenPtr = TokenAfter(tokenPtr);
        CompileWord(envPtr, tokenPtr, interp, words);
    }
    if (parsePtr->numWords <= 2) {
        PushLiteral(envPtr, identity, -1);
        words++;
    }
    if (words > 3) {
        /*
         * Reverse order of arguments to get precise agreement with
         * [expr] in calcuations, including roundoff errors.
         */
        TclEmitInstInt4(INST_REVERSE, words-1, envPtr);
    }
    while (--words > 1) {
        TclEmitOpcode(instruction, envPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * CompileStrictlyBinaryOpCmd --
 *
 *      Utility routine to compile the binary operator commands, that strictly
 *      accept exactly two arguments.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the compiled command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

static int
CompileStrictlyBinaryOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    int instruction,
    CompileEnv *envPtr)
{
    if (parsePtr->numWords != 3) {
        return TCL_ERROR;
    }
    return CompileAssociativeBinaryOpCmd(interp, parsePtr,
            NULL, instruction, envPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * CompileComparisonOpCmd --
 *
 *      Utility routine to compile the n-ary comparison operator commands.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the compiled command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

static int
CompileComparisonOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    int instruction,
    CompileEnv *envPtr)
{
    Tcl_Token *tokenPtr;
    DefineLineInformation;      /* TIP #280 */

    if (parsePtr->numWords < 3) {
        PushLiteral(envPtr, "1", 1);
    } else if (parsePtr->numWords == 3) {
        tokenPtr = TokenAfter(parsePtr->tokenPtr);
        CompileWord(envPtr, tokenPtr, interp, 1);
        tokenPtr = TokenAfter(tokenPtr);
        CompileWord(envPtr, tokenPtr, interp, 2);
        TclEmitOpcode(instruction, envPtr);
    } else if (envPtr->procPtr == NULL) {
        /*
         * No local variable space!
         */

        return TCL_ERROR;
    } else {
        int tmpIndex = TclFindCompiledLocal(NULL, 0, 1, envPtr->procPtr);
        int words;

        tokenPtr = TokenAfter(parsePtr->tokenPtr);
        CompileWord(envPtr, tokenPtr, interp, 1);
        tokenPtr = TokenAfter(tokenPtr);
        CompileWord(envPtr, tokenPtr, interp, 2);
        if (tmpIndex <= 255) {
            TclEmitInstInt1(INST_STORE_SCALAR1, tmpIndex, envPtr);
        } else {
            TclEmitInstInt4(INST_STORE_SCALAR4, tmpIndex, envPtr);
        }
        TclEmitOpcode(instruction, envPtr);
        for (words=3 ; words<parsePtr->numWords ;) {
            if (tmpIndex <= 255) {
                TclEmitInstInt1(INST_LOAD_SCALAR1, tmpIndex, envPtr);
            } else {
                TclEmitInstInt4(INST_LOAD_SCALAR4, tmpIndex, envPtr);
            }
            tokenPtr = TokenAfter(tokenPtr);
            CompileWord(envPtr, tokenPtr, interp, words);
            if (++words < parsePtr->numWords) {
                if (tmpIndex <= 255) {
                    TclEmitInstInt1(INST_STORE_SCALAR1, tmpIndex, envPtr);
                } else {
                    TclEmitInstInt4(INST_STORE_SCALAR4, tmpIndex, envPtr);
                }
            }
            TclEmitOpcode(instruction, envPtr);
        }
        for (; words>3 ; words--) {
            TclEmitOpcode(INST_BITAND, envPtr);
        }

        /*
         * Drop the value from the temp variable; retaining that reference
         * might be expensive elsewhere.
         */

        PushLiteral(envPtr, "", 0);
        if (tmpIndex <= 255) {
            TclEmitInstInt1(INST_STORE_SCALAR1, tmpIndex, envPtr);
        } else {
            TclEmitInstInt4(INST_STORE_SCALAR4, tmpIndex, envPtr);
        }
        TclEmitOpcode(INST_POP, envPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompile*OpCmd --
 *
 *      Procedures called to compile the corresponding "::tcl::mathop::*"
 *      commands. These are all wrappers around the utility operator command
 *      compiler functions, except for the compilers for subtraction and
 *      division, which are special.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the compiled command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileInvertOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileUnaryOpCmd(interp, parsePtr, INST_BITNOT, envPtr);
}

int
TclCompileNotOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileUnaryOpCmd(interp, parsePtr, INST_LNOT, envPtr);
}

int
TclCompileAddOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileAssociativeBinaryOpCmd(interp, parsePtr, "0", INST_ADD,
            envPtr);
}

int
TclCompileMulOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileAssociativeBinaryOpCmd(interp, parsePtr, "1", INST_MULT,
            envPtr);
}

int
TclCompileAndOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileAssociativeBinaryOpCmd(interp, parsePtr, "-1", INST_BITAND,
            envPtr);
}

int
TclCompileOrOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileAssociativeBinaryOpCmd(interp, parsePtr, "0", INST_BITOR,
            envPtr);
}

int
TclCompileXorOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileAssociativeBinaryOpCmd(interp, parsePtr, "0", INST_BITXOR,
            envPtr);
}

int
TclCompilePowOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    /*
     * This one has its own implementation because the ** operator is
     * the only one with right associativity.
     */
    Tcl_Token *tokenPtr = parsePtr->tokenPtr;
    DefineLineInformation;      /* TIP #280 */
    int words;

    for (words=1 ; words<parsePtr->numWords ; words++) {
        tokenPtr = TokenAfter(tokenPtr);
        CompileWord(envPtr, tokenPtr, interp, words);
    }
    if (parsePtr->numWords <= 2) {
        PushLiteral(envPtr, "1", 1);
        words++;
    }
    while (--words > 1) {
        TclEmitOpcode(INST_EXPON, envPtr);
    }
    return TCL_OK;
}

int
TclCompileLshiftOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileStrictlyBinaryOpCmd(interp, parsePtr, INST_LSHIFT, envPtr);
}

int
TclCompileRshiftOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileStrictlyBinaryOpCmd(interp, parsePtr, INST_RSHIFT, envPtr);
}

int
TclCompileModOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileStrictlyBinaryOpCmd(interp, parsePtr, INST_MOD, envPtr);
}

int
TclCompileNeqOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileStrictlyBinaryOpCmd(interp, parsePtr, INST_NEQ, envPtr);
}

int
TclCompileStrneqOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileStrictlyBinaryOpCmd(interp, parsePtr, INST_STR_NEQ, envPtr);
}

int
TclCompileInOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileStrictlyBinaryOpCmd(interp, parsePtr, INST_LIST_IN, envPtr);
}

int
TclCompileNiOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileStrictlyBinaryOpCmd(interp, parsePtr, INST_LIST_NOT_IN,
            envPtr);
}

int
TclCompileLessOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileComparisonOpCmd(interp, parsePtr, INST_LT, envPtr);
}

int
TclCompileLeqOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileComparisonOpCmd(interp, parsePtr, INST_LE, envPtr);
}

int
TclCompileGreaterOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileComparisonOpCmd(interp, parsePtr, INST_GT, envPtr);
}

int
TclCompileGeqOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileComparisonOpCmd(interp, parsePtr, INST_GE, envPtr);
}

int
TclCompileEqOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileComparisonOpCmd(interp, parsePtr, INST_EQ, envPtr);
}

int
TclCompileStreqOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    return CompileComparisonOpCmd(interp, parsePtr, INST_STR_EQ, envPtr);
}

int
TclCompileMinusOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    Tcl_Token *tokenPtr = parsePtr->tokenPtr;
    DefineLineInformation;      /* TIP #280 */
    int words;

    if (parsePtr->numWords == 1) {
        /* Fallback to direct eval to report syntax error */
        return TCL_ERROR;
    }
    for (words=1 ; words<parsePtr->numWords ; words++) {
        tokenPtr = TokenAfter(tokenPtr);
        CompileWord(envPtr, tokenPtr, interp, words);
    }
    if (words == 2) {
        TclEmitOpcode(INST_UMINUS, envPtr);
        return TCL_OK;
    }
    if (words == 3) {
        TclEmitOpcode(INST_SUB, envPtr);
        return TCL_OK;
    }
    /*
     * Reverse order of arguments to get precise agreement with
     * [expr] in calcuations, including roundoff errors.
     */
    TclEmitInstInt4(INST_REVERSE, words-1, envPtr);
    while (--words > 1) {
        TclEmitInstInt4(INST_REVERSE, 2, envPtr);
        TclEmitOpcode(INST_SUB, envPtr);
    }
    return TCL_OK;
}

int
TclCompileDivOpCmd(
    Tcl_Interp *interp,
    Tcl_Parse *parsePtr,
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)
{
    Tcl_Token *tokenPtr = parsePtr->tokenPtr;
    DefineLineInformation;      /* TIP #280 */
    int words;

    if (parsePtr->numWords == 1) {
        /* Fallback to direct eval to report syntax error */
        return TCL_ERROR;
    }
    if (parsePtr->numWords == 2) {
        PushLiteral(envPtr, "1.0", 3);
    }
    for (words=1 ; words<parsePtr->numWords ; words++) {
        tokenPtr = TokenAfter(tokenPtr);
        CompileWord(envPtr, tokenPtr, interp, words);
    }
    if (words <= 3) {
        TclEmitOpcode(INST_DIV, envPtr);
        return TCL_OK;
    }
    /*
     * Reverse order of arguments to get precise agreement with
     * [expr] in calcuations, including roundoff errors.
     */
    TclEmitInstInt4(INST_REVERSE, words-1, envPtr);
    while (--words > 1) {
        TclEmitInstInt4(INST_REVERSE, 2, envPtr);
        TclEmitOpcode(INST_DIV, envPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * IndexTailVarIfKnown --
 *
 *      Procedure used in compiling [global] and [variable] commands. It
 *      inspects the variable name described by varTokenPtr and, if the tail
 *      is known at compile time, defines a corresponding local variable.
 *
 * Results:
 *      Returns the variable's index in the table of compiled locals if the
 *      tail is known at compile time, or -1 otherwise.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static int
IndexTailVarIfKnown(
    Tcl_Interp *interp,
    Tcl_Token *varTokenPtr,     /* Token representing the variable name */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Obj *tailPtr;
    const char *tailName, *p;
    int len, n = varTokenPtr->numComponents;
    Tcl_Token *lastTokenPtr;
    int full, localIndex;

    /*
     * Determine if the tail is (a) known at compile time, and (b) not an
     * array element. Should any of these fail, return an error so that
     * the non-compiled command will be called at runtime.
     * In order for the tail to be known at compile time, the last token
     * in the word has to be constant and contain "::" if it is not the
     * only one.
     */

    if (envPtr->procPtr == NULL) {
        return -1;
    }

    TclNewObj(tailPtr);
    if (TclWordKnownAtCompileTime(varTokenPtr, tailPtr)) {
        full = 1;
        lastTokenPtr = varTokenPtr;
    } else {
        full = 0;
        lastTokenPtr = varTokenPtr + n;
        if (!TclWordKnownAtCompileTime(lastTokenPtr, tailPtr)) {
            Tcl_DecrRefCount(tailPtr);
            return -1;
        }
    }

    tailName = TclGetStringFromObj(tailPtr, &len);

    if (len) {
        if (*(tailName+len-1) == ')') {
            /*
             * Possible array: bail out
             */

            Tcl_DecrRefCount(tailPtr);
            return -1;
        }

        /*
         * Get the tail: immediately after the last '::'
         */

        for(p = tailName + len -1; p > tailName; p--) {
            if ((*p == ':') && (*(p-1) == ':')) {
                p++;
                break;
            }
        }
        if (!full && (p == tailName)) {
            /*
             * No :: in the last component
             */
            Tcl_DecrRefCount(tailPtr);
            return -1;
        }
        len -= p - tailName;
        tailName = p;
    }

    localIndex = TclFindCompiledLocal(tailName, len,
            /*create*/ TCL_CREATE_VAR,
            envPtr->procPtr);
    Tcl_DecrRefCount(tailPtr);
    return localIndex;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileUpvarCmd --
 *
 *      Procedure called to compile the "upvar" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "upvar" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileUpvarCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *tokenPtr, *otherTokenPtr, *localTokenPtr;
    int simpleVarName, isScalar, localIndex, numWords, i;
    DefineLineInformation;      /* TIP #280 */
    Tcl_Obj *objPtr = Tcl_NewObj();

    if (envPtr->procPtr == NULL) {
        Tcl_DecrRefCount(objPtr);
        return TCL_ERROR;
    }

    numWords = parsePtr->numWords;
    if (numWords < 3) {
        Tcl_DecrRefCount(objPtr);
        return TCL_ERROR;
    }

    /*
     * Push the frame index if it is known at compile time
     */

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    if(TclWordKnownAtCompileTime(tokenPtr, objPtr)) {
        CallFrame *framePtr;
        Tcl_ObjType *newTypePtr, *typePtr = objPtr->typePtr;

        /*
         * Attempt to convert to a level reference. Note that TclObjGetFrame
         * only changes the obj type when a conversion was successful.
         */

        TclObjGetFrame(interp, objPtr, &framePtr);
        newTypePtr = objPtr->typePtr;
        Tcl_DecrRefCount(objPtr);

        if (newTypePtr != typePtr) {
            if(numWords%2) {
                return TCL_ERROR;
            }
            CompileWord(envPtr, tokenPtr, interp, 1);
            otherTokenPtr = TokenAfter(tokenPtr);
            i = 4;
        } else {
            if(!(numWords%2)) {
                return TCL_ERROR;
            }
            PushLiteral(envPtr, "1", 1);
            otherTokenPtr = tokenPtr;
            i = 3;
        }
    } else {
        Tcl_DecrRefCount(objPtr);
        return TCL_ERROR;
    }

    /*
     * Loop over the (otherVar, thisVar) pairs. If any of the thisVar is not a
     * local variable, return an error so that the non-compiled command will
     * be called at runtime.
     */

    for(; i<=numWords; i+=2, otherTokenPtr = TokenAfter(localTokenPtr)) {
        localTokenPtr = TokenAfter(otherTokenPtr);

        CompileWord(envPtr, otherTokenPtr, interp, 1);
        PushVarName(interp, localTokenPtr, envPtr, TCL_CREATE_VAR,
                &localIndex, &simpleVarName, &isScalar,
                mapPtr->loc[eclIndex].line[1]);

        if((localIndex < 0) || !isScalar) {
            return TCL_ERROR;
        }
        TclEmitInstInt4(INST_UPVAR, localIndex, envPtr);
    }

    /*
     * Pop the frame index, and set the result to empty
     */

    TclEmitOpcode(INST_POP, envPtr);
    PushLiteral(envPtr, "", 0);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileNamespaceCmd --
 *
 *      Procedure called to compile the "namespace" command; currently, only
 *      the subcommand "namespace upvar" is compiled to bytecodes.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "namespace upvar"
 *      command at runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileNamespaceCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *tokenPtr, *otherTokenPtr, *localTokenPtr;
    int simpleVarName, isScalar, localIndex, numWords, i;
    DefineLineInformation;      /* TIP #280 */

    if (envPtr->procPtr == NULL) {
        return TCL_ERROR;
    }

    /*
     * Only compile [namespace upvar ...]: needs an odd number of args, >=5
     */

    numWords = parsePtr->numWords;
    if (!(numWords%2) || (numWords < 5)) {
        return TCL_ERROR;
    }

    /*
     * Check if the second argument is "upvar"
     */

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    if ((tokenPtr->size != 5)  /* 5 == strlen("upvar") */
            || strncmp(tokenPtr->start, "upvar", 5)) {
        return TCL_ERROR;
    }

    /*
     * Push the namespace
     */

    tokenPtr = TokenAfter(tokenPtr);
    CompileWord(envPtr, tokenPtr, interp, 1);

    /*
     * Loop over the (otherVar, thisVar) pairs. If any of the thisVar is not a
     * local variable, return an error so that the non-compiled command will
     * be called at runtime.
     */

    localTokenPtr = tokenPtr;
    for(i=4; i<=numWords; i+=2) {
        otherTokenPtr = TokenAfter(localTokenPtr);
        localTokenPtr = TokenAfter(otherTokenPtr);

        CompileWord(envPtr, otherTokenPtr, interp, 1);
        PushVarName(interp, localTokenPtr, envPtr, TCL_CREATE_VAR,
                &localIndex, &simpleVarName, &isScalar,
                mapPtr->loc[eclIndex].line[1]);

        if((localIndex < 0) || !isScalar) {
            return TCL_ERROR;
        }
        TclEmitInstInt4(INST_NSUPVAR, localIndex, envPtr);
    }

    /*
     * Pop the namespace, and set the result to empty
     */

    TclEmitOpcode(INST_POP, envPtr);
    PushLiteral(envPtr, "", 0);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileGlobalCmd --
 *
 *      Procedure called to compile the "global" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "global" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileGlobalCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *varTokenPtr;
    int localIndex, numWords, i;
    DefineLineInformation;      /* TIP #280 */

    numWords = parsePtr->numWords;
    if (numWords < 2) {
        return TCL_ERROR;
    }

    /*
     * 'global' has no effect outside of proc bodies; handle that at runtime
     */

    if (envPtr->procPtr == NULL) {
        return TCL_ERROR;
    }

    /*
     * Push the namespace
     */

    PushLiteral(envPtr, "::", 2);

    /*
     * Loop over the variables.
     */

    varTokenPtr = TokenAfter(parsePtr->tokenPtr);
    for(i=2; i<=numWords; varTokenPtr = TokenAfter(varTokenPtr),i++) {
        localIndex = IndexTailVarIfKnown(interp, varTokenPtr, envPtr);

        if(localIndex < 0) {
            return TCL_ERROR;
        }

        CompileWord(envPtr, varTokenPtr, interp, 1);
        TclEmitInstInt4(INST_NSUPVAR, localIndex, envPtr);
    }

    /*
     * Pop the namespace, and set the result to empty
     */

    TclEmitOpcode(INST_POP, envPtr);
    PushLiteral(envPtr, "", 0);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileVariableCmd --
 *
 *      Procedure called to compile the "variable" command.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "variable" command at
 *      runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileVariableCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *varTokenPtr, *valueTokenPtr;
    int localIndex, numWords, i;
    DefineLineInformation;      /* TIP #280 */

    numWords = parsePtr->numWords;
    if (numWords < 2) {
        return TCL_ERROR;
    }

    /*
     * Bail out if not compiling a proc body
     */

    if (envPtr->procPtr == NULL) {
        return TCL_ERROR;
    }

    /*
     * Loop over the (var, value) pairs.
     */

    valueTokenPtr = parsePtr->tokenPtr;
    for(i=2; i<=numWords; i+=2) {
        varTokenPtr = TokenAfter(valueTokenPtr);
        valueTokenPtr = TokenAfter(varTokenPtr);

        localIndex = IndexTailVarIfKnown(interp, varTokenPtr, envPtr);

        if(localIndex < 0) {
            return TCL_ERROR;
        }

        CompileWord(envPtr, varTokenPtr, interp, 1);
        TclEmitInstInt4(INST_VARIABLE, localIndex, envPtr);

        if (i != numWords) {
            /*
             * A value has been given: set the variable, pop the value
             */

            CompileWord(envPtr, valueTokenPtr, interp, 1);
            TclEmitInstInt4(INST_STORE_SCALAR4, localIndex, envPtr);
            TclEmitOpcode(INST_POP, envPtr);
        }
    }

    /*
     * Set the result to empty
     */

    PushLiteral(envPtr, "", 0);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileEnsemble --
 *
 *      Procedure called to compile an ensemble command. Note that most
 *      ensembles are not compiled, since modifying a compiled ensemble causes
 *      a invalidation of all existing bytecode (expensive!) which is not
 *      normally warranted.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the subcommands of the
 *      ensemble at runtime if a compile-time mapping is possible.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileEnsemble(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *tokenPtr;
    Tcl_Obj *mapObj, *subcmdObj, *targetCmdObj, *listObj, **elems;
    Tcl_Command ensemble = (Tcl_Command) cmdPtr;
    Tcl_Parse synthetic;
    int len, numBytes, result, flags = 0, i;
    const char *word;

    if (parsePtr->numWords < 2) {
        return TCL_ERROR;
    }

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    if (tokenPtr->type != TCL_TOKEN_SIMPLE_WORD) {
        /*
         * Too hard.
         */

        return TCL_ERROR;
    }

    word = tokenPtr[1].start;
    numBytes = tokenPtr[1].size;

    /*
     * There's a sporting chance we'll be able to compile this. But now we
     * must check properly. To do that, check that we're compiling an ensemble
     * that has a compilable command as its appropriate subcommand.
     */

    if (Tcl_GetEnsembleMappingDict(NULL, ensemble, &mapObj) != TCL_OK
            || mapObj == NULL) {
        /*
         * Either not an ensemble or a mapping isn't installed. Crud. Too hard
         * to proceed.
         */

        return TCL_ERROR;
    }

    /*
     * Next, get the flags. We need them on several code paths.
     */

    (void) Tcl_GetEnsembleFlags(NULL, ensemble, &flags);

    /*
     * Check to see if there's also a subcommand list; must check to see if
     * the subcommand we are calling is in that list if it exists, since that
     * list filters the entries in the map.
     */

    (void) Tcl_GetEnsembleSubcommandList(NULL, ensemble, &listObj);
    if (listObj != NULL) {
        int sclen;
        const char *str;
        Tcl_Obj *matchObj = NULL;

        if (Tcl_ListObjGetElements(NULL, listObj, &len, &elems) != TCL_OK) {
            return TCL_ERROR;
        }
        for (i=0 ; i<len ; i++) {
            str = Tcl_GetStringFromObj(elems[i], &sclen);
            if (sclen==numBytes && !memcmp(word, str, (unsigned) numBytes)) {
                /*
                 * Exact match! Excellent!
                 */

                result = Tcl_DictObjGet(NULL, mapObj,elems[i], &targetCmdObj);
                if (result != TCL_OK || targetCmdObj == NULL) {
                    return TCL_ERROR;
                }
                goto doneMapLookup;
            }

            /*
             * Check to see if we've got a prefix match. A single prefix match
             * is fine, and allows us to refine our dictionary lookup, but
             * multiple prefix matches is a Bad Thing and will prevent us from
             * making progress. Note that we cannot do the lookup immediately
             * in the prefix case; might be another entry later in the list
             * that causes things to fail.
             */

            if ((flags & TCL_ENSEMBLE_PREFIX)
                    && strncmp(word, str, (unsigned) numBytes) == 0) {
                if (matchObj != NULL) {
                    return TCL_ERROR;
                }
                matchObj = elems[i];
            }
        }
        if (matchObj != NULL) {
            result = Tcl_DictObjGet(NULL, mapObj, matchObj, &targetCmdObj);
            if (result != TCL_OK || targetCmdObj == NULL) {
                return TCL_ERROR;
            }
            goto doneMapLookup;
        }
        return TCL_ERROR;
    } else {
        /*
         * No map, so check the dictionary directly.
         */

        TclNewStringObj(subcmdObj, word, numBytes);
        result = Tcl_DictObjGet(NULL, mapObj, subcmdObj, &targetCmdObj);
        TclDecrRefCount(subcmdObj);
        if (result == TCL_OK && targetCmdObj != NULL) {
            /*
             * Got it. Skip the fiddling around with prefixes.
             */

            goto doneMapLookup;
        }

        /*
         * We've not literally got a valid subcommand. But maybe we have a
         * prefix. Check if prefix matches are allowed.
         */

        if (flags & TCL_ENSEMBLE_PREFIX) {
            Tcl_DictSearch s;
            int done, matched;
            Tcl_Obj *tmpObj;

            /*
             * Iterate over the keys in the dictionary, checking to see if
             * we're a prefix.
             */

            Tcl_DictObjFirst(NULL,mapObj,&s,&subcmdObj,&tmpObj,&done);
            matched = 0;
            while (!done) {
                if (strncmp(TclGetString(subcmdObj), word,
                        (unsigned) numBytes) == 0) {
                    if (matched++) {
                        /*
                         * Must have matched twice! Not unique, so no point
                         * looking further.
                         */

                        break;
                    }
                    targetCmdObj = tmpObj;
                }
                Tcl_DictObjNext(&s, &subcmdObj, &tmpObj, &done);
            }
            Tcl_DictObjDone(&s);

            /*
             * If we have anything other than a single match, we've failed the
             * unique prefix check.
             */

            if (matched != 1) {
                return TCL_ERROR;
            }
        } else {
            return TCL_ERROR;
        }
    }

    /*
     * OK, we definitely map to something. But what?
     *
     * The command we map to is the first word out of the map element. Note
     * that we also reject dealing with multi-element rewrites if we are in a
     * safe interpreter, as there is otherwise a (highly gnarly!) way to make
     * Tcl crash open to exploit.
     */

  doneMapLookup:
    if (Tcl_ListObjGetElements(NULL, targetCmdObj, &len, &elems) != TCL_OK) {
        return TCL_ERROR;
    }
    if (len > 1 && Tcl_IsSafe(interp)) {
        return TCL_ERROR;
    }
    targetCmdObj = elems[0];

    Tcl_IncrRefCount(targetCmdObj);
    cmdPtr = (Command *) Tcl_GetCommandFromObj(interp, targetCmdObj);
    TclDecrRefCount(targetCmdObj);
    if (cmdPtr == NULL || cmdPtr->compileProc == NULL) {
        /*
         * Maps to an undefined command or a command without a compiler.
         * Cannot compile.
         */

        return TCL_ERROR;
    }

    /*
     * Now we've done the mapping process, can now actually try to compile.
     * We do this by handing off to the subcommand's actual compiler. But to
     * do that, we have to perform some trickery to rewrite the arguments.
     */

    TclParseInit(interp, NULL, 0, &synthetic);
    synthetic.numWords = parsePtr->numWords - 2 + len;
    TclGrowParseTokenArray(&synthetic, 2*len);
    synthetic.numTokens = 2*len;

    /*
     * Now we have the space to work in, install something rewritten. Note
     * that we are here praying for all our might that none of these words are
     * a script; the error detection code will crash if that happens and there
     * is nothing we can do to avoid it!
     */

    for (i=0 ; i<len ; i++) {
        int sclen;
        const char *str = Tcl_GetStringFromObj(elems[i], &sclen);

        synthetic.tokenPtr[2*i].type = TCL_TOKEN_SIMPLE_WORD;
        synthetic.tokenPtr[2*i].start = str;
        synthetic.tokenPtr[2*i].size = sclen;
        synthetic.tokenPtr[2*i].numComponents = 1;

        synthetic.tokenPtr[2*i+1].type = TCL_TOKEN_TEXT;
        synthetic.tokenPtr[2*i+1].start = str;
        synthetic.tokenPtr[2*i+1].size = sclen;
        synthetic.tokenPtr[2*i+1].numComponents = 0;
    }

    /*
     * Copy over the real argument tokens.
     */

    for (i=len; i<synthetic.numWords; i++) {
        int toCopy;
        tokenPtr = TokenAfter(tokenPtr);
        toCopy = tokenPtr->numComponents + 1;
        TclGrowParseTokenArray(&synthetic, toCopy);
        memcpy(synthetic.tokenPtr + synthetic.numTokens, tokenPtr,
                sizeof(Tcl_Token) * toCopy);
        synthetic.numTokens += toCopy;
    }

    /*
     * Hand off compilation to the subcommand compiler. At last!
     */

    result = cmdPtr->compileProc(interp, &synthetic, cmdPtr, envPtr);

    /*
     * Clean up if necessary.
     */

    Tcl_FreeParse(&synthetic);
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCompileInfoExistsCmd --
 *
 *      Procedure called to compile the "info exists" subcommand.
 *
 * Results:
 *      Returns TCL_OK for a successful compile. Returns TCL_ERROR to defer
 *      evaluation to runtime.
 *
 * Side effects:
 *      Instructions are added to envPtr to execute the "info exists"
 *      subcommand at runtime.
 *
 *----------------------------------------------------------------------
 */

int
TclCompileInfoExistsCmd(
    Tcl_Interp *interp,         /* Used for error reporting. */
    Tcl_Parse *parsePtr,        /* Points to a parse structure for the command
                                 * created by Tcl_ParseCommand. */
    Command *cmdPtr,            /* Points to defintion of command being
                                 * compiled. */
    CompileEnv *envPtr)         /* Holds resulting instructions. */
{
    Tcl_Token *tokenPtr;
    int isScalar, simpleVarName, localIndex;
    DefineLineInformation;      /* TIP #280 */

    if (parsePtr->numWords != 2) {
        return TCL_ERROR;
    }

    /*
     * Decide if we can use a frame slot for the var/array name or if we need
     * to emit code to compute and push the name at runtime. We use a frame
     * slot (entry in the array of local vars) if we are compiling a procedure
     * body and if the name is simple text that does not include namespace
     * qualifiers.
     */

    tokenPtr = TokenAfter(parsePtr->tokenPtr);
    PushVarName(interp, tokenPtr, envPtr, TCL_CREATE_VAR, &localIndex,
            &simpleVarName, &isScalar, mapPtr->loc[eclIndex].line[1]);

    /*
     * Emit instruction to check the variable for existence.
     */

    if (simpleVarName) {
        if (isScalar) {
            if (localIndex < 0) {
                TclEmitOpcode(INST_EXIST_STK, envPtr);
            } else {
                TclEmitInstInt4(INST_EXIST_SCALAR, localIndex, envPtr);
            }
        } else {
            if (localIndex < 0) {
                TclEmitOpcode(INST_EXIST_ARRAY_STK, envPtr);
            } else {
                TclEmitInstInt4(INST_EXIST_ARRAY, localIndex, envPtr);
            }
        }
    } else {
        TclEmitOpcode(INST_EXIST_STK, envPtr);
    }

    return TCL_OK;
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */