source: downloads/tcl8.5.2/generic/tclVar.c @ 42

/*
 * tclVar.c --
 *
 *      This file contains routines that implement Tcl variables (both scalars
 *      and arrays).
 *
 *      The implementation of arrays is modelled after an initial
 *      implementation by Mark Diekhans and Karl Lehenbauer.
 *
 * Copyright (c) 1987-1994 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 * Copyright (c) 1998-1999 by Scriptics Corporation.
 * Copyright (c) 2001 by Kevin B. Kenny. All rights reserved.
 * Copyright (c) 2007 Miguel Sofer
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclVar.c,v 1.160 2008/03/11 17:23:56 msofer Exp $
 */

#include "tclInt.h"

/*
 * Prototypes for the variable hash key methods.
 */

static Tcl_HashEntry *  AllocVarEntry(Tcl_HashTable *tablePtr, void *keyPtr);
static void             FreeVarEntry(Tcl_HashEntry *hPtr);
static int              CompareVarKeys(void *keyPtr, Tcl_HashEntry *hPtr);
static unsigned int     HashVarKey(Tcl_HashTable *tablePtr, void *keyPtr);

static Tcl_HashKeyType tclVarHashKeyType = {
    TCL_HASH_KEY_TYPE_VERSION,  /* version */
    0,                          /* flags */
    HashVarKey,                 /* hashKeyProc */
    CompareVarKeys,             /* compareKeysProc */
    AllocVarEntry,              /* allocEntryProc */
    FreeVarEntry                /* freeEntryProc */
};

static inline Var *     VarHashCreateVar(TclVarHashTable *tablePtr,
                            Tcl_Obj *key, int *newPtr);
static inline Var *     VarHashFirstVar(TclVarHashTable *tablePtr,
                            Tcl_HashSearch *searchPtr);
static inline Var *     VarHashNextVar(Tcl_HashSearch *searchPtr);
static inline void      CleanupVar(Var *varPtr, Var *arrayPtr);

#define VarHashGetValue(hPtr) \
    ((Var *) ((char *)hPtr - TclOffset(VarInHash, entry)))

static inline Var *
VarHashCreateVar(
    TclVarHashTable *tablePtr,
    Tcl_Obj *key,
    int *newPtr)
{
    Tcl_HashEntry *hPtr = Tcl_CreateHashEntry((Tcl_HashTable *) tablePtr,
            (char *) key, newPtr);

    if (hPtr) {
        return VarHashGetValue(hPtr);
    } else {
        return NULL;
    }
}

#define VarHashFindVar(tablePtr, key) \
    VarHashCreateVar((tablePtr), (key), NULL)

#define VarHashInvalidateEntry(varPtr) \
    ((varPtr)->flags |= VAR_DEAD_HASH)

#define VarHashDeleteEntry(varPtr) \
    Tcl_DeleteHashEntry(&(((VarInHash *) varPtr)->entry))

#define VarHashFirstEntry(tablePtr, searchPtr) \
    Tcl_FirstHashEntry((Tcl_HashTable *) (tablePtr), (searchPtr))

#define VarHashNextEntry(searchPtr) \
    Tcl_NextHashEntry((searchPtr))

static inline Var *
VarHashFirstVar(
    TclVarHashTable *tablePtr,
    Tcl_HashSearch *searchPtr)
{
    Tcl_HashEntry *hPtr = VarHashFirstEntry(tablePtr, searchPtr);

    if (hPtr) {
        return VarHashGetValue(hPtr);
    } else {
        return NULL;
    }
}

static inline Var *
VarHashNextVar(
    Tcl_HashSearch *searchPtr)
{
    Tcl_HashEntry *hPtr = VarHashNextEntry(searchPtr);

    if (hPtr) {
        return VarHashGetValue(hPtr);
    } else {
        return NULL;
    }
}

#define VarHashGetKey(varPtr) \
    (((VarInHash *)(varPtr))->entry.key.objPtr)

#define VarHashDeleteTable(tablePtr) \
    Tcl_DeleteHashTable((Tcl_HashTable *) (tablePtr))

/*
 * The strings below are used to indicate what went wrong when a variable
 * access is denied.
 */

static const char *noSuchVar =          "no such variable";
static const char *isArray =            "variable is array";
static const char *needArray =          "variable isn't array";
static const char *noSuchElement =      "no such element in array";
static const char *danglingElement =
        "upvar refers to element in deleted array";
static const char *danglingVar =
        "upvar refers to variable in deleted namespace";
static const char *badNamespace =       "parent namespace doesn't exist";
static const char *missingName =        "missing variable name";
static const char *isArrayElement =
        "name refers to an element in an array";

/*
 * A test to see if we are in a call frame that has local variables. This is
 * true if we are inside a procedure body.
 */

#define HasLocalVars(framePtr) ((framePtr)->isProcCallFrame & FRAME_IS_PROC)

/*
 * Forward references to functions defined later in this file:
 */

static void             AppendLocals(Tcl_Interp *interp, Tcl_Obj *listPtr,
                            Tcl_Obj *patternPtr, int includeLinks);
static void             DeleteSearches(Interp *iPtr, Var *arrayVarPtr);
static void             DeleteArray(Interp *iPtr, Tcl_Obj *arrayNamePtr,
                            Var *varPtr, int flags);
static Tcl_Var          ObjFindNamespaceVar(Tcl_Interp *interp,
                            Tcl_Obj *namePtr, Tcl_Namespace *contextNsPtr,
                            int flags);
static int              ObjMakeUpvar(Tcl_Interp *interp,
                            CallFrame *framePtr, Tcl_Obj *otherP1Ptr,
                            const char *otherP2, const int otherFlags,
                            Tcl_Obj *myNamePtr, int myFlags, int index);
static ArraySearch *    ParseSearchId(Tcl_Interp *interp, const Var *varPtr,
                            Tcl_Obj *varNamePtr, Tcl_Obj *handleObj);
static void             UnsetVarStruct(Var *varPtr, Var *arrayPtr,
                            Interp *iPtr, Tcl_Obj *part1Ptr,
                            Tcl_Obj *part2Ptr, int flags);
static int              SetArraySearchObj(Tcl_Interp *interp,
                            Tcl_Obj *objPtr);

/*
 * Functions defined in this file that may be exported in the future for use
 * by the bytecode compiler and engine or to the public interface.
 */

MODULE_SCOPE Var *      TclLookupSimpleVar(Tcl_Interp *interp,
                            Tcl_Obj *varNamePtr, int flags, const int create,
                            const char **errMsgPtr, int *indexPtr);

static Tcl_DupInternalRepProc   DupLocalVarName;
static Tcl_FreeInternalRepProc  FreeLocalVarName;
static Tcl_UpdateStringProc     PanicOnUpdateVarName;

static Tcl_FreeInternalRepProc  FreeParsedVarName;
static Tcl_DupInternalRepProc   DupParsedVarName;
static Tcl_UpdateStringProc     UpdateParsedVarName;

static Tcl_UpdateStringProc     PanicOnUpdateVarName;
static Tcl_SetFromAnyProc       PanicOnSetVarName;

/*
 * Types of Tcl_Objs used to cache variable lookups.
 *
 * localVarName - INTERNALREP DEFINITION:
 *   ptrAndLongRep.ptr:   pointer to name obj in varFramePtr->localCache
 *                        or NULL if it is this same obj
 *   ptrAndLongRep.value: index into locals table
 *
 * nsVarName - INTERNALREP DEFINITION:
 *   twoPtrValue.ptr1:  pointer to the namespace containing the reference
 *   twoPtrValue.ptr2:  pointer to the corresponding Var
 *
 * parsedVarName - INTERNALREP DEFINITION:
 *   twoPtrValue.ptr1:  pointer to the array name Tcl_Obj, or NULL if it is a
 *                      scalar variable
 *   twoPtrValue.ptr2:  pointer to the element name string (owned by this
 *                      Tcl_Obj), or NULL if it is a scalar variable
 */

static Tcl_ObjType localVarNameType = {
    "localVarName",
    FreeLocalVarName, DupLocalVarName, PanicOnUpdateVarName, PanicOnSetVarName
};

/*
 * Caching of namespace variables disabled: no simple way was found to avoid
 * interfering with the resolver's idea of variable existence. A cached
 * varName may keep a variable's name in the namespace's hash table, which is
 * the resolver's criterion for existence (see test namespace-17.10).
 */

#define ENABLE_NS_VARNAME_CACHING 0

#if ENABLE_NS_VARNAME_CACHING
static Tcl_FreeInternalRepProc FreeNsVarName;
static Tcl_DupInternalRepProc DupNsVarName;

static Tcl_ObjType tclNsVarNameType = {
    "namespaceVarName",
    FreeNsVarName, DupNsVarName, PanicOnUpdateVarName, PanicOnSetVarName
};
#endif

static Tcl_ObjType tclParsedVarNameType = {
    "parsedVarName",
    FreeParsedVarName, DupParsedVarName, UpdateParsedVarName, PanicOnSetVarName
};

/*
 * Type of Tcl_Objs used to speed up array searches.
 *
 * INTERNALREP DEFINITION:
 *   twoPtrValue.ptr1:  searchIdNumber (cast to pointer)
 *   twoPtrValue.ptr2:  variableNameStartInString (cast to pointer)
 *
 * Note that the value stored in ptr2 is the offset into the string of the
 * start of the variable name and not the address of the variable name itself,
 * as this can be safely copied.
 */

Tcl_ObjType tclArraySearchType = {
    "array search",
    NULL, NULL, NULL, SetArraySearchObj
};

Var *
TclVarHashCreateVar(
    TclVarHashTable *tablePtr,
    const char *key,
    int *newPtr)
{
    Tcl_Obj *keyPtr;
    Var *varPtr;

    keyPtr = Tcl_NewStringObj(key, -1);
    Tcl_IncrRefCount(keyPtr);
    varPtr = VarHashCreateVar(tablePtr, keyPtr, newPtr);
    Tcl_DecrRefCount(keyPtr);

    return varPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCleanupVar --
 *
 *      This function is called when it looks like it may be OK to free up a
 *      variable's storage. If the variable is in a hashtable, its Var
 *      structure and hash table entry will be freed along with those of its
 *      containing array, if any. This function is called, for example, when
 *      a trace on a variable deletes a variable.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If the variable (or its containing array) really is dead and in a
 *      hashtable, then its Var structure, and possibly its hash table entry,
 *      is freed up.
 *
 *----------------------------------------------------------------------
 */

static inline void
CleanupVar(
    Var *varPtr,                /* Pointer to variable that may be a candidate
                                 * for being expunged. */
    Var *arrayPtr)              /* Array that contains the variable, or NULL
                                 * if this variable isn't an array element. */
{
    if (TclIsVarUndefined(varPtr) && TclIsVarInHash(varPtr)
            && !TclIsVarTraced(varPtr)
            && (VarHashRefCount(varPtr) == !TclIsVarDeadHash(varPtr))) {
        if (VarHashRefCount(varPtr) == 0) {
            ckfree((char *) varPtr);
        } else {
            VarHashDeleteEntry(varPtr);
        }
    }
    if (arrayPtr != NULL && TclIsVarUndefined(arrayPtr) &&
            TclIsVarInHash(arrayPtr) && !TclIsVarTraced(arrayPtr) &&
            (VarHashRefCount(arrayPtr) == !TclIsVarDeadHash(arrayPtr))) {
        if (VarHashRefCount(arrayPtr) == 0) {
            ckfree((char *) arrayPtr);
        } else {
            VarHashDeleteEntry(arrayPtr);
        }
    }
}

void
TclCleanupVar(
    Var *varPtr,                /* Pointer to variable that may be a candidate
                                 * for being expunged. */
    Var *arrayPtr)              /* Array that contains the variable, or NULL
                                 * if this variable isn't an array element. */
{
    CleanupVar(varPtr, arrayPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * TclLookupVar --
 *
 *      This function is used to locate a variable given its name(s). It has
 *      been mostly superseded by TclObjLookupVar, it is now only used by the
 *      trace code. It is kept in tcl8.5 mainly because it is in the internal
 *      stubs table, so that some extension may be calling it.
 *
 * Results:
 *      The return value is a pointer to the variable structure indicated by
 *      part1 and part2, or NULL if the variable couldn't be found. If the
 *      variable is found, *arrayPtrPtr is filled in with the address of the
 *      variable structure for the array that contains the variable (or NULL
 *      if the variable is a scalar). If the variable can't be found and
 *      either createPart1 or createPart2 are 1, a new as-yet-undefined
 *      (VAR_UNDEFINED) variable structure is created, entered into a hash
 *      table, and returned.
 *
 *      If the variable isn't found and creation wasn't specified, or some
 *      other error occurs, NULL is returned and an error message is left in
 *      the interp's result if TCL_LEAVE_ERR_MSG is set in flags.
 *
 *      Note: it's possible for the variable returned to be VAR_UNDEFINED even
 *      if createPart1 or createPart2 are 1 (these only cause the hash table
 *      entry or array to be created). For example, the variable might be a
 *      global that has been unset but is still referenced by a procedure, or
 *      a variable that has been unset but it only being kept in existence (if
 *      VAR_UNDEFINED) by a trace.
 *
 * Side effects:
 *      New hashtable entries may be created if createPart1 or createPart2
 *      are 1.
 *
 *----------------------------------------------------------------------
 */

Var *
TclLookupVar(
    Tcl_Interp *interp,         /* Interpreter to use for lookup. */
    const char *part1,          /* If part2 isn't NULL, this is the name of an
                                 * array. Otherwise, this is a full variable
                                 * name that could include a parenthesized
                                 * array element. */
    const char *part2,          /* Name of element within array, or NULL. */
    int flags,                  /* Only TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * and TCL_LEAVE_ERR_MSG bits matter. */
    const char *msg,            /* Verb to use in error messages, e.g. "read"
                                 * or "set". Only needed if TCL_LEAVE_ERR_MSG
                                 * is set in flags. */
    int createPart1,            /* If 1, create hash table entry for part 1 of
                                 * name, if it doesn't already exist. If 0,
                                 * return error if it doesn't exist. */
    int createPart2,            /* If 1, create hash table entry for part 2 of
                                 * name, if it doesn't already exist. If 0,
                                 * return error if it doesn't exist. */
    Var **arrayPtrPtr)          /* If the name refers to an element of an
                                 * array, *arrayPtrPtr gets filled in with
                                 * address of array variable. Otherwise this
                                 * is set to NULL. */
{
    Tcl_Obj *part1Ptr;
    Var *varPtr;

    part1Ptr = Tcl_NewStringObj(part1, -1);
    Tcl_IncrRefCount(part1Ptr);

    varPtr = TclObjLookupVar(interp, part1Ptr, part2, flags, msg,
            createPart1, createPart2, arrayPtrPtr);

    TclDecrRefCount(part1Ptr);
    return varPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * TclObjLookupVar, TclObjLookupVarEx --
 *
 *      This function is used by virtually all of the variable code to locate
 *      a variable given its name(s). The parsing into array/element
 *      components and (if possible) the lookup results are cached in
 *      part1Ptr, which is converted to one of the varNameTypes.
 *
 * Results:
 *      The return value is a pointer to the variable structure indicated by
 *      part1Ptr and part2, or NULL if the variable couldn't be found. If *
 *      the variable is found, *arrayPtrPtr is filled with the address of the
 *      variable structure for the array that contains the variable (or NULL
 *      if the variable is a scalar). If the variable can't be found and
 *      either createPart1 or createPart2 are 1, a new as-yet-undefined
 *      (VAR_UNDEFINED) variable structure is created, entered into a hash
 *      table, and returned.
 *
 *      If the variable isn't found and creation wasn't specified, or some
 *      other error occurs, NULL is returned and an error message is left in
 *      the interp's result if TCL_LEAVE_ERR_MSG is set in flags.
 *
 *      Note: it's possible for the variable returned to be VAR_UNDEFINED even
 *      if createPart1 or createPart2 are 1 (these only cause the hash table
 *      entry or array to be created). For example, the variable might be a
 *      global that has been unset but is still referenced by a procedure, or
 *      a variable that has been unset but it only being kept in existence (if
 *      VAR_UNDEFINED) by a trace.
 *
 * Side effects:
 *      New hashtable entries may be created if createPart1 or createPart2
 *      are 1. The object part1Ptr is converted to one of localVarNameType,
 *      tclNsVarNameType or tclParsedVarNameType and caches as much of the
 *      lookup as it can.
 *
 *----------------------------------------------------------------------
 */

Var *
TclObjLookupVar(
    Tcl_Interp *interp,         /* Interpreter to use for lookup. */
    register Tcl_Obj *part1Ptr, /* If part2 isn't NULL, this is the name of an
                                 * array. Otherwise, this is a full variable
                                 * name that could include a parenthesized
                                 * array element. */
    const char *part2,          /* Name of element within array, or NULL. */
    int flags,                  /* Only TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * and TCL_LEAVE_ERR_MSG bits matter. */
    const char *msg,            /* Verb to use in error messages, e.g. "read"
                                 * or "set". Only needed if TCL_LEAVE_ERR_MSG
                                 * is set in flags. */
    const int createPart1,      /* If 1, create hash table entry for part 1 of
                                 * name, if it doesn't already exist. If 0,
                                 * return error if it doesn't exist. */
    const int createPart2,      /* If 1, create hash table entry for part 2 of
                                 * name, if it doesn't already exist. If 0,
                                 * return error if it doesn't exist. */
    Var **arrayPtrPtr)          /* If the name refers to an element of an
                                 * array, *arrayPtrPtr gets filled in with
                                 * address of array variable. Otherwise this
                                 * is set to NULL. */
{
    Tcl_Obj *part2Ptr;
    Var *resPtr;

    if (part2) {
        part2Ptr = Tcl_NewStringObj(part2, -1);
        Tcl_IncrRefCount(part2Ptr);
    } else {
        part2Ptr = NULL;
    }

    resPtr = TclObjLookupVarEx(interp, part1Ptr, part2Ptr,
            flags, msg, createPart1, createPart2, arrayPtrPtr);

    if (part2Ptr) {
        Tcl_DecrRefCount(part2Ptr);
    }

    return resPtr;
}

Var *
TclObjLookupVarEx(
    Tcl_Interp *interp,         /* Interpreter to use for lookup. */
    Tcl_Obj *part1Ptr,          /* If part2Ptr isn't NULL, this is the name of
                                 * an array. Otherwise, this is a full
                                 * variable name that could include a
                                 * parenthesized array element. */
    Tcl_Obj *part2Ptr,          /* Name of element within array, or NULL. */
    int flags,                  /* Only TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * and TCL_LEAVE_ERR_MSG bits matter. */
    const char *msg,            /* Verb to use in error messages, e.g. "read"
                                 * or "set". Only needed if TCL_LEAVE_ERR_MSG
                                 * is set in flags. */
    const int createPart1,      /* If 1, create hash table entry for part 1 of
                                 * name, if it doesn't already exist. If 0,
                                 * return error if it doesn't exist. */
    const int createPart2,      /* If 1, create hash table entry for part 2 of
                                 * name, if it doesn't already exist. If 0,
                                 * return error if it doesn't exist. */
    Var **arrayPtrPtr)          /* If the name refers to an element of an
                                 * array, *arrayPtrPtr gets filled in with
                                 * address of array variable. Otherwise this
                                 * is set to NULL. */
{
    Interp *iPtr = (Interp *) interp;
    register Var *varPtr;       /* Points to the variable's in-frame Var
                                 * structure. */
    char *part1;
    int index, len1, len2;
    int parsed = 0;
    Tcl_Obj *objPtr;
    const Tcl_ObjType *typePtr = part1Ptr->typePtr;
    const char *errMsg = NULL;
    CallFrame *varFramePtr = iPtr->varFramePtr;
    Namespace *nsPtr;
    char *part2 = part2Ptr? TclGetString(part2Ptr):NULL;
    char *newPart2 = NULL;

    *arrayPtrPtr = NULL;

    if (varFramePtr) {
        nsPtr = varFramePtr->nsPtr;
    } else {
        /*
         * Some variables in the global ns have to be initialized before the
         * root call frame is in place.
         */

        nsPtr = NULL;
    }

    if (typePtr == &localVarNameType) {
        int localIndex;

    localVarNameTypeHandling:
        localIndex = (int) part1Ptr->internalRep.ptrAndLongRep.value;
        if (HasLocalVars(varFramePtr)
                && !(flags & (TCL_GLOBAL_ONLY | TCL_NAMESPACE_ONLY))
                && (localIndex < varFramePtr->numCompiledLocals)) {
            /*
             * Use the cached index if the names coincide.
             */

            Tcl_Obj *namePtr = (Tcl_Obj *)
                    part1Ptr->internalRep.ptrAndLongRep.ptr;
            Tcl_Obj *checkNamePtr = localName(iPtr->varFramePtr, localIndex);

            if ((!namePtr && (checkNamePtr == part1Ptr)) ||
                    (namePtr && (checkNamePtr == namePtr))) {
                varPtr = (Var *) &(varFramePtr->compiledLocals[localIndex]);
                goto donePart1;
            }
        }
        goto doneParsing;
#if ENABLE_NS_VARNAME_CACHING
    } else if (typePtr == &tclNsVarNameType) {
        int useGlobal, useReference;
        Namespace *cachedNsPtr = part1Ptr->internalRep.twoPtrValue.ptr1;
        varPtr = part1Ptr->internalRep.twoPtrValue.ptr2;

        useGlobal = (cachedNsPtr == iPtr->globalNsPtr) && (
                (flags & TCL_GLOBAL_ONLY) ||
                (part1[0]==':' && part1[1]==':') ||
                (!HasLocalVars(varFramePtr) && (nsPtr==iPtr->globalNsPtr)));

        useReference = useGlobal || ((cachedNsPtr == nsPtr) && (
                (flags & TCL_NAMESPACE_ONLY) ||
                (!HasLocalVars(varFramePtr) && !(flags & TCL_GLOBAL_ONLY) &&
                /*
                 * Careful: an undefined ns variable could be hiding a valid
                 * global reference.
                 */
                !TclIsVarUndefined(varPtr))));

        if (useReference && !TclIsVarDeadHash(varPtr)) {
            /*
             * A straight global or namespace reference, use it. It isn't so
             * simple to deal with 'implicit' namespace references, i.e.,
             * those where the reference could be to either a namespace or a
             * global variable. Those we lookup again.
             *
             * If TclIsVarDeadHash(varPtr), this might be a reference to a
             * variable in a deleted namespace, kept alive by e.g. part1Ptr.
             * We could conceivably be so unlucky that a new namespace was
             * created at the same address as the deleted one, so to be safe
             * we test for a valid hPtr.
             */

            goto donePart1;
        }
        goto doneParsing;
#endif
    }

    /*
     * If part1Ptr is a tclParsedVarNameType, separate it into the pre-parsed
     * parts.
     */

    if (typePtr == &tclParsedVarNameType) {
        if (part1Ptr->internalRep.twoPtrValue.ptr1 != NULL) {
            if (part2Ptr != NULL) {
                /*
                 * ERROR: part1Ptr is already an array element, cannot specify
                 * a part2.
                 */

                if (flags & TCL_LEAVE_ERR_MSG) {
                    TclObjVarErrMsg(interp, part1Ptr, part2Ptr, msg,
                            noSuchVar, -1);
                }
                return NULL;
            }
            part2 = newPart2 = part1Ptr->internalRep.twoPtrValue.ptr2;
            if (newPart2) {
                part2Ptr = Tcl_NewStringObj(newPart2, -1);
                Tcl_IncrRefCount(part2Ptr);
            }
            part1Ptr = part1Ptr->internalRep.twoPtrValue.ptr1;
            typePtr = part1Ptr->typePtr;
            if (typePtr == &localVarNameType) {
                goto localVarNameTypeHandling;
            }
        }
        parsed = 1;
    }
    part1 = TclGetStringFromObj(part1Ptr, &len1);

    if (!parsed && (*(part1 + len1 - 1) == ')')) {
        /*
         * part1Ptr is possibly an unparsed array element.
         */

        register int i;

        len2 = -1;
        for (i = 0; i < len1; i++) {
            if (*(part1 + i) == '(') {
                if (part2Ptr != NULL) {
                    if (flags & TCL_LEAVE_ERR_MSG) {
                        TclObjVarErrMsg(interp, part1Ptr, part2Ptr, msg,
                                needArray, -1);
                    }
                    return NULL;
                }

                /*
                 * part1Ptr points to an array element; first copy the element
                 * name to a new string part2.
                 */

                part2 = part1 + i + 1;
                len2 = len1 - i - 2;
                len1 = i;

                newPart2 = ckalloc((unsigned int) (len2+1));
                memcpy(newPart2, part2, (unsigned int) len2);
                *(newPart2+len2) = '\0';
                part2 = newPart2;
                part2Ptr = Tcl_NewStringObj(newPart2, -1);
                Tcl_IncrRefCount(part2Ptr);

                /*
                 * Free the internal rep of the original part1Ptr, now renamed
                 * objPtr, and set it to tclParsedVarNameType.
                 */

                objPtr = part1Ptr;
                TclFreeIntRep(objPtr);
                objPtr->typePtr = &tclParsedVarNameType;

                /*
                 * Define a new string object to hold the new part1Ptr, i.e.,
                 * the array name. Set the internal rep of objPtr, reset
                 * typePtr and part1 to contain the references to the array
                 * name.
                 */

                TclNewStringObj(part1Ptr, part1, len1);
                Tcl_IncrRefCount(part1Ptr);

                objPtr->internalRep.twoPtrValue.ptr1 = part1Ptr;
                objPtr->internalRep.twoPtrValue.ptr2 = (void *) part2;

                typePtr = part1Ptr->typePtr;
                part1 = TclGetString(part1Ptr);
                break;
            }
        }
    }

  doneParsing:
    /*
     * part1Ptr is not an array element; look it up, and convert it to one of
     * the cached types if possible.
     */

    TclFreeIntRep(part1Ptr);
    part1Ptr->typePtr = NULL;

    varPtr = TclLookupSimpleVar(interp, part1Ptr, flags, createPart1,
            &errMsg, &index);
    if (varPtr == NULL) {
        if ((errMsg != NULL) && (flags & TCL_LEAVE_ERR_MSG)) {
            TclObjVarErrMsg(interp, part1Ptr, part2Ptr, msg, errMsg, -1);
        }
        if (newPart2) {
            Tcl_DecrRefCount(part2Ptr);
        }
        return NULL;
    }

    /*
     * Cache the newly found variable if possible.
     */

    if (index >= 0) {
        /*
         * An indexed local variable.
         */

        part1Ptr->typePtr = &localVarNameType;
        if (part1Ptr != localName(iPtr->varFramePtr, index)) {
            part1Ptr->internalRep.ptrAndLongRep.ptr =
                    localName(iPtr->varFramePtr, index);
            Tcl_IncrRefCount((Tcl_Obj *)
                    part1Ptr->internalRep.ptrAndLongRep.ptr);
        } else {
            part1Ptr->internalRep.ptrAndLongRep.ptr = NULL;
        }
        part1Ptr->internalRep.ptrAndLongRep.value = (long) index;
#if ENABLE_NS_VARNAME_CACHING
    } else if (index > -3) {
        /*
         * A cacheable namespace or global variable.
         */

        Namespace *nsPtr;

        nsPtr = ((index == -1) ? iPtr->globalNsPtr : varFramePtr->nsPtr);
        varPtr->refCount++;
        part1Ptr->typePtr = &tclNsVarNameType;
        part1Ptr->internalRep.twoPtrValue.ptr1 = nsPtr;
        part1Ptr->internalRep.twoPtrValue.ptr2 = varPtr;
#endif
    } else {
        /*
         * At least mark part1Ptr as already parsed.
         */

        part1Ptr->typePtr = &tclParsedVarNameType;
        part1Ptr->internalRep.twoPtrValue.ptr1 = NULL;
        part1Ptr->internalRep.twoPtrValue.ptr2 = NULL;
    }

  donePart1:
#if 0
    if (varPtr == NULL) {
        if (flags & TCL_LEAVE_ERR_MSG) {
            part1 = TclGetString(part1Ptr);
            TclObjVarErrMsg(interp, part1Ptr, part2Ptr, msg,
                    "Cached variable reference is NULL.", -1);
        }
        return NULL;
    }
#endif
    while (TclIsVarLink(varPtr)) {
        varPtr = varPtr->value.linkPtr;
    }

    if (part2Ptr != NULL) {
        /*
         * Array element sought: look it up.
         */

        *arrayPtrPtr = varPtr;
        varPtr = TclLookupArrayElement(interp, part1Ptr, part2Ptr, flags, msg,
                createPart1, createPart2, varPtr, -1);
        if (newPart2) {
            Tcl_DecrRefCount(part2Ptr);
        }
    }
    return varPtr;
}

/*
 * This flag bit should not interfere with TCL_GLOBAL_ONLY,
 * TCL_NAMESPACE_ONLY, or TCL_LEAVE_ERR_MSG; it signals that the variable
 * lookup is performed for upvar (or similar) purposes, with slightly
 * different rules:
 *    - Bug #696893 - variable is either proc-local or in the current
 *      namespace; never follow the second (global) resolution path
 *    - Bug #631741 - do not use special namespace or interp resolvers
 *
 * It should also not collide with the (deprecated) TCL_PARSE_PART1 flag
 * (Bug #835020)
 */

#define AVOID_RESOLVERS 0x40000

/*
 *----------------------------------------------------------------------
 *
 * TclLookupSimpleVar --
 *
 *      This function is used by to locate a simple variable (i.e., not an
 *      array element) given its name.
 *
 * Results:
 *      The return value is a pointer to the variable structure indicated by
 *      varName, or NULL if the variable couldn't be found. If the variable
 *      can't be found and create is 1, a new as-yet-undefined (VAR_UNDEFINED)
 *      variable structure is created, entered into a hash table, and
 *      returned.
 *
 *      If the current CallFrame corresponds to a proc and the variable found
 *      is one of the compiledLocals, its index is placed in *indexPtr.
 *      Otherwise, *indexPtr will be set to (according to the needs of
 *      TclObjLookupVar):
 *          -1 a global reference
 *          -2 a reference to a namespace variable
 *          -3 a non-cachable reference, i.e., one of:
 *              . non-indexed local var
 *              . a reference of unknown origin;
 *              . resolution by a namespace or interp resolver
 *
 *      If the variable isn't found and creation wasn't specified, or some
 *      other error occurs, NULL is returned and the corresponding error
 *      message is left in *errMsgPtr.
 *
 *      Note: it's possible for the variable returned to be VAR_UNDEFINED even
 *      if create is 1 (this only causes the hash table entry to be created).
 *      For example, the variable might be a global that has been unset but is
 *      still referenced by a procedure, or a variable that has been unset but
 *      it only being kept in existence (if VAR_UNDEFINED) by a trace.
 *
 * Side effects:
 *      A new hashtable entry may be created if create is 1.
 *
 *----------------------------------------------------------------------
 */

Var *
TclLookupSimpleVar(
    Tcl_Interp *interp,         /* Interpreter to use for lookup. */
    Tcl_Obj *varNamePtr,        /* This is a simple variable name that could
                                 * represent a scalar or an array. */
    int flags,                  /* Only TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * AVOID_RESOLVERS and TCL_LEAVE_ERR_MSG bits
                                 * matter. */
    const int create,           /* If 1, create hash table entry for varname,
                                 * if it doesn't already exist. If 0, return
                                 * error if it doesn't exist. */
    const char **errMsgPtr,
    int *indexPtr)
{
    Interp *iPtr = (Interp *) interp;
    CallFrame *varFramePtr = iPtr->varFramePtr;
                                /* Points to the procedure call frame whose
                                 * variables are currently in use. Same as the
                                 * current procedure's frame, if any, unless
                                 * an "uplevel" is executing. */
    TclVarHashTable *tablePtr;  /* Points to the hashtable, if any, in which
                                 * to look up the variable. */
    Tcl_Var var;                /* Used to search for global names. */
    Var *varPtr;                /* Points to the Var structure returned for
                                 * the variable. */
    Namespace *varNsPtr, *cxtNsPtr, *dummy1Ptr, *dummy2Ptr;
    ResolverScheme *resPtr;
    int isNew, i, result;
    const char *varName = TclGetString(varNamePtr);

    varPtr = NULL;
    varNsPtr = NULL;            /* Set non-NULL if a nonlocal variable. */
    *indexPtr = -3;

    if (flags & TCL_GLOBAL_ONLY) {
        cxtNsPtr = iPtr->globalNsPtr;
    } else {
        cxtNsPtr = iPtr->varFramePtr->nsPtr;
    }

    /*
     * If this namespace has a variable resolver, then give it first crack at
     * the variable resolution. It may return a Tcl_Var value, it may signal
     * to continue onward, or it may signal an error.
     */

    if ((cxtNsPtr->varResProc != NULL || iPtr->resolverPtr != NULL)
            && !(flags & AVOID_RESOLVERS)) {
        resPtr = iPtr->resolverPtr;
        if (cxtNsPtr->varResProc) {
            result = (*cxtNsPtr->varResProc)(interp, varName,
                    (Tcl_Namespace *) cxtNsPtr, flags, &var);
        } else {
            result = TCL_CONTINUE;
        }

        while (result == TCL_CONTINUE && resPtr) {
            if (resPtr->varResProc) {
                result = (*resPtr->varResProc)(interp, varName,
                        (Tcl_Namespace *) cxtNsPtr, flags, &var);
            }
            resPtr = resPtr->nextPtr;
        }

        if (result == TCL_OK) {
            return (Var *) var;
        } else if (result != TCL_CONTINUE) {
            return NULL;
        }
    }

    /*
     * Look up varName. Look it up as either a namespace variable or as a
     * local variable in a procedure call frame (varFramePtr). Interpret
     * varName as a namespace variable if:
     *    1) so requested by a TCL_GLOBAL_ONLY or TCL_NAMESPACE_ONLY flag,
     *    2) there is no active frame (we're at the global :: scope),
     *    3) the active frame was pushed to define the namespace context for a
     *       "namespace eval" or "namespace inscope" command,
     *    4) the name has namespace qualifiers ("::"s).
     * Otherwise, if varName is a local variable, search first in the frame's
     * array of compiler-allocated local variables, then in its hashtable for
     * runtime-created local variables.
     *
     * If create and the variable isn't found, create the variable and, if
     * necessary, create varFramePtr's local var hashtable.
     */

    if (((flags & (TCL_GLOBAL_ONLY | TCL_NAMESPACE_ONLY)) != 0)
            || !HasLocalVars(varFramePtr)
            || (strstr(varName, "::") != NULL)) {
        const char *tail;
        int lookGlobal = (flags & TCL_GLOBAL_ONLY)
                || (cxtNsPtr == iPtr->globalNsPtr)
                || ((*varName == ':') && (*(varName+1) == ':'));

        if (lookGlobal) {
            *indexPtr = -1;
            flags = (flags | TCL_GLOBAL_ONLY) & ~TCL_NAMESPACE_ONLY;
        } else {
            if (flags & AVOID_RESOLVERS) {
                flags = (flags | TCL_NAMESPACE_ONLY);
            }
            if (flags & TCL_NAMESPACE_ONLY) {
                *indexPtr = -2;
            }
        }

        /*
         * Don't pass TCL_LEAVE_ERR_MSG, we may yet create the variable, or
         * otherwise generate our own error!
         */

        varPtr = (Var *) ObjFindNamespaceVar(interp, varNamePtr,
                (Tcl_Namespace *) cxtNsPtr,
                (flags | AVOID_RESOLVERS) & ~TCL_LEAVE_ERR_MSG);
        if (varPtr == NULL) {
            Tcl_Obj *tailPtr;

            if (create) {       /* Var wasn't found so create it. */
                TclGetNamespaceForQualName(interp, varName, cxtNsPtr,
                        flags, &varNsPtr, &dummy1Ptr, &dummy2Ptr, &tail);
                if (varNsPtr == NULL) {
                    *errMsgPtr = badNamespace;
                    return NULL;
                } else if (tail == NULL) {
                    *errMsgPtr = missingName;
                    return NULL;
                }
                if (tail != varName) {
                    tailPtr = Tcl_NewStringObj(tail, -1);
                } else {
                    tailPtr = varNamePtr;
                }
                varPtr = VarHashCreateVar(&varNsPtr->varTable, tailPtr,
                        &isNew);
                if (lookGlobal) {
                    /*
                     * The variable was created starting from the global
                     * namespace: a global reference is returned even if it
                     * wasn't explicitly requested.
                     */

                    *indexPtr = -1;
                } else {
                    *indexPtr = -2;
                }
            } else {            /* Var wasn't found and not to create it. */
                *errMsgPtr = noSuchVar;
                return NULL;
            }
        }
    } else {                    /* Local var: look in frame varFramePtr. */
        Proc *procPtr = varFramePtr->procPtr;
        int localCt = procPtr->numCompiledLocals;
        Tcl_Obj **objPtrPtr = &varFramePtr->localCachePtr->varName0;

        for (i=0 ; i<localCt ; i++, objPtrPtr++) {
            register Tcl_Obj *objPtr = *objPtrPtr;

            if (objPtr) {
                char *localName = TclGetString(objPtr);

                if ((varName[0] == localName[0])
                        && (strcmp(varName, localName) == 0)) {
                    *indexPtr = i;
                    return (Var *) &varFramePtr->compiledLocals[i];
                }
            }
        }
        tablePtr = varFramePtr->varTablePtr;
        if (create) {
            if (tablePtr == NULL) {
                tablePtr = (TclVarHashTable *)
                        ckalloc(sizeof(TclVarHashTable));
                TclInitVarHashTable(tablePtr, NULL);
                varFramePtr->varTablePtr = tablePtr;
            }
            varPtr = VarHashCreateVar(tablePtr, varNamePtr, &isNew);
        } else {
            varPtr = NULL;
            if (tablePtr != NULL) {
                varPtr = VarHashFindVar(tablePtr, varNamePtr);
            }
            if (varPtr == NULL) {
                *errMsgPtr = noSuchVar;
            }
        }
    }
    return varPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * TclLookupArrayElement --
 *
 *      This function is used to locate a variable which is in an array's
 *      hashtable given a pointer to the array's Var structure and the
 *      element's name.
 *
 * Results:
 *      The return value is a pointer to the variable structure , or NULL if
 *      the variable couldn't be found.
 *
 *      If arrayPtr points to a variable that isn't an array and createPart1
 *      is 1, the corresponding variable will be converted to an array.
 *      Otherwise, NULL is returned and an error message is left in the
 *      interp's result if TCL_LEAVE_ERR_MSG is set in flags.
 *
 *      If the variable is not found and createPart2 is 1, the variable is
 *      created. Otherwise, NULL is returned and an error message is left in
 *      the interp's result if TCL_LEAVE_ERR_MSG is set in flags.
 *
 *      Note: it's possible for the variable returned to be VAR_UNDEFINED even
 *      if createPart1 or createPart2 are 1 (these only cause the hash table
 *      entry or array to be created). For example, the variable might be a
 *      global that has been unset but is still referenced by a procedure, or
 *      a variable that has been unset but it only being kept in existence (if
 *      VAR_UNDEFINED) by a trace.
 *
 * Side effects:
 *      The variable at arrayPtr may be converted to be an array if
 *      createPart1 is 1. A new hashtable entry may be created if createPart2
 *      is 1.
 *
 *----------------------------------------------------------------------
 */

Var *
TclLookupArrayElement(
    Tcl_Interp *interp,         /* Interpreter to use for lookup. */
    Tcl_Obj *arrayNamePtr,      /* This is the name of the array, or NULL if
                                 * index>= 0. */
    Tcl_Obj *elNamePtr,         /* Name of element within array. */
    const int flags,            /* Only TCL_LEAVE_ERR_MSG bit matters. */
    const char *msg,            /* Verb to use in error messages, e.g. "read"
                                 * or "set". Only needed if TCL_LEAVE_ERR_MSG
                                 * is set in flags. */
    const int createArray,      /* If 1, transform arrayName to be an array if
                                 * it isn't one yet and the transformation is
                                 * possible. If 0, return error if it isn't
                                 * already an array. */
    const int createElem,       /* If 1, create hash table entry for the
                                 * element, if it doesn't already exist. If 0,
                                 * return error if it doesn't exist. */
    Var *arrayPtr,              /* Pointer to the array's Var structure. */
    int index)                  /* If >=0, the index of the local array. */
{
    int isNew;
    Var *varPtr;
    TclVarHashTable *tablePtr;
    Namespace *nsPtr;

    /*
     * We're dealing with an array element. Make sure the variable is an array
     * and look up the element (create the element if desired).
     */

    if (TclIsVarUndefined(arrayPtr) && !TclIsVarArrayElement(arrayPtr)) {
        if (!createArray) {
            if (flags & TCL_LEAVE_ERR_MSG) {
                TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg,
                        noSuchVar, index);
            }
            return NULL;
        }

        /*
         * Make sure we are not resurrecting a namespace variable from a
         * deleted namespace!
         */

        if (TclIsVarDeadHash(arrayPtr)) {
            if (flags & TCL_LEAVE_ERR_MSG) {
                TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg,
                        danglingVar, index);
            }
            return NULL;
        }

        TclSetVarArray(arrayPtr);
        tablePtr = (TclVarHashTable *) ckalloc(sizeof(TclVarHashTable));
        arrayPtr->value.tablePtr = tablePtr;

        if (TclIsVarInHash(arrayPtr) && TclGetVarNsPtr(arrayPtr)) {
            nsPtr = TclGetVarNsPtr(arrayPtr);
        } else {
            nsPtr = NULL;
        }
        TclInitVarHashTable(arrayPtr->value.tablePtr, nsPtr);
    } else if (!TclIsVarArray(arrayPtr)) {
        if (flags & TCL_LEAVE_ERR_MSG) {
            TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg, needArray,
                    index);
        }
        return NULL;
    }

    if (createElem) {
        varPtr = VarHashCreateVar(arrayPtr->value.tablePtr, elNamePtr,
                &isNew);
        if (isNew) {
            if (arrayPtr->flags & VAR_SEARCH_ACTIVE) {
                DeleteSearches((Interp *) interp, arrayPtr);
            }
            TclSetVarArrayElement(varPtr);
        }
    } else {
        varPtr = VarHashFindVar(arrayPtr->value.tablePtr, elNamePtr);
        if (varPtr == NULL) {
            if (flags & TCL_LEAVE_ERR_MSG) {
                TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg,
                        noSuchElement, index);
                Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ELEMENT",
                        TclGetString(elNamePtr), NULL);
            }
        }
    }
    return varPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetVar --
 *
 *      Return the value of a Tcl variable as a string.
 *
 * Results:
 *      The return value points to the current value of varName as a string.
 *      If the variable is not defined or can't be read because of a clash in
 *      array usage then a NULL pointer is returned and an error message is
 *      left in the interp's result if the TCL_LEAVE_ERR_MSG flag is set.
 *      Note: the return value is only valid up until the next change to the
 *      variable; if you depend on the value lasting longer than that, then
 *      make yourself a private copy.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

const char *
Tcl_GetVar(
    Tcl_Interp *interp,         /* Command interpreter in which varName is to
                                 * be looked up. */
    const char *varName,        /* Name of a variable in interp. */
    int flags)                  /* OR-ed combination of TCL_GLOBAL_ONLY,
                                 * TCL_NAMESPACE_ONLY or TCL_LEAVE_ERR_MSG
                                 * bits. */
{
    return Tcl_GetVar2(interp, varName, NULL, flags);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetVar2 --
 *
 *      Return the value of a Tcl variable as a string, given a two-part name
 *      consisting of array name and element within array.
 *
 * Results:
 *      The return value points to the current value of the variable given by
 *      part1 and part2 as a string. If the specified variable doesn't exist,
 *      or if there is a clash in array usage, then NULL is returned and a
 *      message will be left in the interp's result if the TCL_LEAVE_ERR_MSG
 *      flag is set. Note: the return value is only valid up until the next
 *      change to the variable; if you depend on the value lasting longer than
 *      that, then make yourself a private copy.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

const char *
Tcl_GetVar2(
    Tcl_Interp *interp,         /* Command interpreter in which variable is to
                                 * be looked up. */
    const char *part1,          /* Name of an array (if part2 is non-NULL) or
                                 * the name of a variable. */
    const char *part2,          /* If non-NULL, gives the name of an element
                                 * in the array part1. */
    int flags)                  /* OR-ed combination of TCL_GLOBAL_ONLY,
                                 * TCL_NAMESPACE_ONLY and TCL_LEAVE_ERR_MSG *
                                 * bits. */
{
    Tcl_Obj *objPtr;

    objPtr = Tcl_GetVar2Ex(interp, part1, part2, flags);
    if (objPtr == NULL) {
        return NULL;
    }
    return TclGetString(objPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetVar2Ex --
 *
 *      Return the value of a Tcl variable as a Tcl object, given a two-part
 *      name consisting of array name and element within array.
 *
 * Results:
 *      The return value points to the current object value of the variable
 *      given by part1Ptr and part2Ptr. If the specified variable doesn't
 *      exist, or if there is a clash in array usage, then NULL is returned
 *      and a message will be left in the interpreter's result if the
 *      TCL_LEAVE_ERR_MSG flag is set.
 *
 * Side effects:
 *      The ref count for the returned object is _not_ incremented to reflect
 *      the returned reference; if you want to keep a reference to the object
 *      you must increment its ref count yourself.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
Tcl_GetVar2Ex(
    Tcl_Interp *interp,         /* Command interpreter in which variable is to
                                 * be looked up. */
    const char *part1,          /* Name of an array (if part2 is non-NULL) or
                                 * the name of a variable. */
    const char *part2,          /* If non-NULL, gives the name of an element
                                 * in the array part1. */
    int flags)                  /* OR-ed combination of TCL_GLOBAL_ONLY, and
                                 * TCL_LEAVE_ERR_MSG bits. */
{
    Tcl_Obj *part1Ptr, *part2Ptr, *resPtr;

    part1Ptr = Tcl_NewStringObj(part1, -1);
    Tcl_IncrRefCount(part1Ptr);
    if (part2) {
        part2Ptr = Tcl_NewStringObj(part2, -1);
        Tcl_IncrRefCount(part2Ptr);
    } else {
        part2Ptr = NULL;
    }

    resPtr = Tcl_ObjGetVar2(interp, part1Ptr, part2Ptr, flags);

    Tcl_DecrRefCount(part1Ptr);
    if (part2Ptr) {
        Tcl_DecrRefCount(part2Ptr);
    }

    return resPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_ObjGetVar2 --
 *
 *      Return the value of a Tcl variable as a Tcl object, given a two-part
 *      name consisting of array name and element within array.
 *
 * Results:
 *      The return value points to the current object value of the variable
 *      given by part1Ptr and part2Ptr. If the specified variable doesn't
 *      exist, or if there is a clash in array usage, then NULL is returned
 *      and a message will be left in the interpreter's result if the
 *      TCL_LEAVE_ERR_MSG flag is set.
 *
 * Side effects:
 *      The ref count for the returned object is _not_ incremented to reflect
 *      the returned reference; if you want to keep a reference to the object
 *      you must increment its ref count yourself.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
Tcl_ObjGetVar2(
    Tcl_Interp *interp,         /* Command interpreter in which variable is to
                                 * be looked up. */
    register Tcl_Obj *part1Ptr, /* Points to an object holding the name of an
                                 * array (if part2 is non-NULL) or the name of
                                 * a variable. */
    register Tcl_Obj *part2Ptr, /* If non-null, points to an object holding
                                 * the name of an element in the array
                                 * part1Ptr. */
    int flags)                  /* OR-ed combination of TCL_GLOBAL_ONLY and
                                 * TCL_LEAVE_ERR_MSG bits. */
{
    Var *varPtr, *arrayPtr;

    /*
     * Filter to pass through only the flags this interface supports.
     */

    flags &= (TCL_GLOBAL_ONLY|TCL_NAMESPACE_ONLY|TCL_LEAVE_ERR_MSG);
    varPtr = TclObjLookupVarEx(interp, part1Ptr, part2Ptr, flags, "read",
            /*createPart1*/ 0, /*createPart2*/ 1, &arrayPtr);
    if (varPtr == NULL) {
        return NULL;
    }

    return TclPtrGetVar(interp, varPtr, arrayPtr, part1Ptr, part2Ptr,
            flags, -1);
}

/*
 *----------------------------------------------------------------------
 *
 * TclPtrGetVar --
 *
 *      Return the value of a Tcl variable as a Tcl object, given the pointers
 *      to the variable's (and possibly containing array's) VAR structure.
 *
 * Results:
 *      The return value points to the current object value of the variable
 *      given by varPtr. If the specified variable doesn't exist, or if there
 *      is a clash in array usage, then NULL is returned and a message will be
 *      left in the interpreter's result if the TCL_LEAVE_ERR_MSG flag is set.
 *
 * Side effects:
 *      The ref count for the returned object is _not_ incremented to reflect
 *      the returned reference; if you want to keep a reference to the object
 *      you must increment its ref count yourself.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
TclPtrGetVar(
    Tcl_Interp *interp,         /* Command interpreter in which variable is to
                                 * be looked up. */
    register Var *varPtr,       /* The variable to be read.*/
    Var *arrayPtr,              /* NULL for scalar variables, pointer to the
                                 * containing array otherwise. */
    Tcl_Obj *part1Ptr,          /* Name of an array (if part2 is non-NULL) or
                                 * the name of a variable. */
    Tcl_Obj *part2Ptr,          /* If non-NULL, gives the name of an element
                                 * in the array part1. */
    const int flags,            /* OR-ed combination of TCL_GLOBAL_ONLY, and
                                 * TCL_LEAVE_ERR_MSG bits. */
    int index)                  /* Index into the local variable table of the
                                 * variable, or -1. Only used when part1Ptr is
                                 * NULL. */
{
    Interp *iPtr = (Interp *) interp;
    const char *msg;

    /*
     * Invoke any read traces that have been set for the variable.
     */

    if ((varPtr->flags & VAR_TRACED_READ)
            || (arrayPtr && (arrayPtr->flags & VAR_TRACED_READ))) {
        if (TCL_ERROR == TclObjCallVarTraces(iPtr, arrayPtr, varPtr,
                part1Ptr, part2Ptr,
                (flags & (TCL_NAMESPACE_ONLY|TCL_GLOBAL_ONLY))
                | TCL_TRACE_READS, (flags & TCL_LEAVE_ERR_MSG), index)) {
            goto errorReturn;
        }
    }

    /*
     * Return the element if it's an existing scalar variable.
     */

    if (TclIsVarScalar(varPtr) && !TclIsVarUndefined(varPtr)) {
        return varPtr->value.objPtr;
    }

    if (flags & TCL_LEAVE_ERR_MSG) {
        if (TclIsVarUndefined(varPtr) && arrayPtr
                && !TclIsVarUndefined(arrayPtr)) {
            msg = noSuchElement;
        } else if (TclIsVarArray(varPtr)) {
            msg = isArray;
        } else {
            msg = noSuchVar;
        }
        TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "read", msg, index);
    }

    /*
     * An error. If the variable doesn't exist anymore and no-one's using it,
     * then free up the relevant structures and hash table entries.
     */

  errorReturn:
    if (TclIsVarUndefined(varPtr)) {
        TclCleanupVar(varPtr, arrayPtr);
    }
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetObjCmd --
 *
 *      This function is invoked to process the "set" Tcl command. See the
 *      user documentation for details on what it does.
 *
 * Results:
 *      A standard Tcl result value.
 *
 * Side effects:
 *      A variable's value may be changed.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
int
Tcl_SetObjCmd(
    ClientData dummy,           /* Not used. */
    register Tcl_Interp *interp,/* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    Tcl_Obj *varValueObj;

    if (objc == 2) {
        varValueObj = Tcl_ObjGetVar2(interp, objv[1], NULL,TCL_LEAVE_ERR_MSG);
        if (varValueObj == NULL) {
            return TCL_ERROR;
        }
        Tcl_SetObjResult(interp, varValueObj);
        return TCL_OK;
    } else if (objc == 3) {
        varValueObj = Tcl_ObjSetVar2(interp, objv[1], NULL, objv[2],
                TCL_LEAVE_ERR_MSG);
        if (varValueObj == NULL) {
            return TCL_ERROR;
        }
        Tcl_SetObjResult(interp, varValueObj);
        return TCL_OK;
    } else {
        Tcl_WrongNumArgs(interp, 1, objv, "varName ?newValue?");
        return TCL_ERROR;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetVar --
 *
 *      Change the value of a variable.
 *
 * Results:
 *      Returns a pointer to the malloc'ed string which is the character
 *      representation of the variable's new value. The caller must not modify
 *      this string. If the write operation was disallowed then NULL is
 *      returned; if the TCL_LEAVE_ERR_MSG flag is set, then an explanatory
 *      message will be left in the interp's result. Note that the returned
 *      string may not be the same as newValue; this is because variable
 *      traces may modify the variable's value.
 *
 * Side effects:
 *      If varName is defined as a local or global variable in interp, its
 *      value is changed to newValue. If varName isn't currently defined, then
 *      a new global variable by that name is created.
 *
 *----------------------------------------------------------------------
 */

const char *
Tcl_SetVar(
    Tcl_Interp *interp,         /* Command interpreter in which varName is to
                                 * be looked up. */
    const char *varName,        /* Name of a variable in interp. */
    const char *newValue,       /* New value for varName. */
    int flags)                  /* Various flags that tell how to set value:
                                 * any of TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * TCL_APPEND_VALUE, TCL_LIST_ELEMENT,
                                 * TCL_LEAVE_ERR_MSG. */
{
    return Tcl_SetVar2(interp, varName, NULL, newValue, flags);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetVar2 --
 *
 *      Given a two-part variable name, which may refer either to a scalar
 *      variable or an element of an array, change the value of the variable.
 *      If the named scalar or array or element doesn't exist then create one.
 *
 * Results:
 *      Returns a pointer to the malloc'ed string which is the character
 *      representation of the variable's new value. The caller must not modify
 *      this string. If the write operation was disallowed because an array
 *      was expected but not found (or vice versa), then NULL is returned; if
 *      the TCL_LEAVE_ERR_MSG flag is set, then an explanatory message will be
 *      left in the interp's result. Note that the returned string may not be
 *      the same as newValue; this is because variable traces may modify the
 *      variable's value.
 *
 * Side effects:
 *      The value of the given variable is set. If either the array or the
 *      entry didn't exist then a new one is created.
 *
 *----------------------------------------------------------------------
 */

const char *
Tcl_SetVar2(
    Tcl_Interp *interp,         /* Command interpreter in which variable is to
                                 * be looked up. */
    const char *part1,          /* If part2 is NULL, this is name of scalar
                                 * variable. Otherwise it is the name of an
                                 * array. */
    const char *part2,          /* Name of an element within an array, or
                                 * NULL. */
    const char *newValue,       /* New value for variable. */
    int flags)                  /* Various flags that tell how to set value:
                                 * any of TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * TCL_APPEND_VALUE, TCL_LIST_ELEMENT, or
                                 * TCL_LEAVE_ERR_MSG. */
{
    register Tcl_Obj *valuePtr;
    Tcl_Obj *varValuePtr;

    /*
     * Create an object holding the variable's new value and use Tcl_SetVar2Ex
     * to actually set the variable.
     */

    valuePtr = Tcl_NewStringObj(newValue, -1);
    Tcl_IncrRefCount(valuePtr);
    varValuePtr = Tcl_SetVar2Ex(interp, part1, part2, valuePtr, flags);
    Tcl_DecrRefCount(valuePtr);

    if (varValuePtr == NULL) {
        return NULL;
    }
    return TclGetString(varValuePtr);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SetVar2Ex --
 *
 *      Given a two-part variable name, which may refer either to a scalar
 *      variable or an element of an array, change the value of the variable
 *      to a new Tcl object value. If the named scalar or array or element
 *      doesn't exist then create one.
 *
 * Results:
 *      Returns a pointer to the Tcl_Obj holding the new value of the
 *      variable. If the write operation was disallowed because an array was
 *      expected but not found (or vice versa), then NULL is returned; if the
 *      TCL_LEAVE_ERR_MSG flag is set, then an explanatory message will be
 *      left in the interpreter's result. Note that the returned object may
 *      not be the same one referenced by newValuePtr; this is because
 *      variable traces may modify the variable's value.
 *
 * Side effects:
 *      The value of the given variable is set. If either the array or the
 *      entry didn't exist then a new variable is created.
 *
 *      The reference count is decremented for any old value of the variable
 *      and incremented for its new value. If the new value for the variable
 *      is not the same one referenced by newValuePtr (perhaps as a result of
 *      a variable trace), then newValuePtr's ref count is left unchanged by
 *      Tcl_SetVar2Ex. newValuePtr's ref count is also left unchanged if we
 *      are appending it as a string value: that is, if "flags" includes
 *      TCL_APPEND_VALUE but not TCL_LIST_ELEMENT.
 *
 *      The reference count for the returned object is _not_ incremented: if
 *      you want to keep a reference to the object you must increment its ref
 *      count yourself.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
Tcl_SetVar2Ex(
    Tcl_Interp *interp,         /* Command interpreter in which variable is to
                                 * be found. */
    const char *part1,          /* Name of an array (if part2 is non-NULL) or
                                 * the name of a variable. */
    const char *part2,          /* If non-NULL, gives the name of an element
                                 * in the array part1. */
    Tcl_Obj *newValuePtr,       /* New value for variable. */
    int flags)                  /* Various flags that tell how to set value:
                                 * any of TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * TCL_APPEND_VALUE, TCL_LIST_ELEMENT or
                                 * TCL_LEAVE_ERR_MSG. */
{
    Tcl_Obj *part1Ptr, *part2Ptr, *resPtr;

    part1Ptr = Tcl_NewStringObj(part1, -1);
    Tcl_IncrRefCount(part1Ptr);
    if (part2) {
        part2Ptr = Tcl_NewStringObj(part2, -1);
        Tcl_IncrRefCount(part2Ptr);
    } else {
        part2Ptr = NULL;
    }

    resPtr = Tcl_ObjSetVar2(interp, part1Ptr, part2Ptr, newValuePtr, flags);

    Tcl_DecrRefCount(part1Ptr);
    if (part2Ptr) {
        Tcl_DecrRefCount(part2Ptr);
    }

    return resPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_ObjSetVar2 --
 *
 *      This function is the same as Tcl_SetVar2Ex above, except the variable
 *      names are passed in Tcl object instead of strings.
 *
 * Results:
 *      Returns a pointer to the Tcl_Obj holding the new value of the
 *      variable. If the write operation was disallowed because an array was
 *      expected but not found (or vice versa), then NULL is returned; if the
 *      TCL_LEAVE_ERR_MSG flag is set, then an explanatory message will be
 *      left in the interpreter's result. Note that the returned object may
 *      not be the same one referenced by newValuePtr; this is because
 *      variable traces may modify the variable's value.
 *
 * Side effects:
 *      The value of the given variable is set. If either the array or the
 *      entry didn't exist then a new variable is created.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
Tcl_ObjSetVar2(
    Tcl_Interp *interp,         /* Command interpreter in which variable is to
                                 * be found. */
    register Tcl_Obj *part1Ptr, /* Points to an object holding the name of an
                                 * array (if part2 is non-NULL) or the name of
                                 * a variable. */
    register Tcl_Obj *part2Ptr, /* If non-NULL, points to an object holding
                                 * the name of an element in the array
                                 * part1Ptr. */
    Tcl_Obj *newValuePtr,       /* New value for variable. */
    int flags)                  /* Various flags that tell how to set value:
                                 * any of TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * TCL_APPEND_VALUE, TCL_LIST_ELEMENT, or
                                 * TCL_LEAVE_ERR_MSG. */
{
    Var *varPtr, *arrayPtr;

    /*
     * Filter to pass through only the flags this interface supports.
     */

    flags &= (TCL_GLOBAL_ONLY|TCL_NAMESPACE_ONLY|TCL_LEAVE_ERR_MSG
            |TCL_APPEND_VALUE|TCL_LIST_ELEMENT);
    varPtr = TclObjLookupVarEx(interp, part1Ptr, part2Ptr, flags, "set",
            /*createPart1*/ 1, /*createPart2*/ 1, &arrayPtr);
    if (varPtr == NULL) {
        if (newValuePtr->refCount == 0) {
            Tcl_DecrRefCount(newValuePtr);
        }
        return NULL;
    }

    return TclPtrSetVar(interp, varPtr, arrayPtr, part1Ptr, part2Ptr,
            newValuePtr, flags, -1);
}

/*
 *----------------------------------------------------------------------
 *
 * TclPtrSetVar --
 *
 *      This function is the same as Tcl_SetVar2Ex above, except that it
 *      requires pointers to the variable's Var structs in addition to the
 *      variable names.
 *
 * Results:
 *      Returns a pointer to the Tcl_Obj holding the new value of the
 *      variable. If the write operation was disallowed because an array was
 *      expected but not found (or vice versa), then NULL is returned; if the
 *      TCL_LEAVE_ERR_MSG flag is set, then an explanatory message will be
 *      left in the interpreter's result. Note that the returned object may
 *      not be the same one referenced by newValuePtr; this is because
 *      variable traces may modify the variable's value.
 *
 * Side effects:
 *      The value of the given variable is set. If either the array or the
 *      entry didn't exist then a new variable is created.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
TclPtrSetVar(
    Tcl_Interp *interp,         /* Command interpreter in which variable is to
                                 * be looked up. */
    register Var *varPtr,       /* Reference to the variable to set. */
    Var *arrayPtr,              /* Reference to the array containing the
                                 * variable, or NULL if the variable is a
                                 * scalar. */
    Tcl_Obj *part1Ptr,          /* Name of an array (if part2 is non-NULL) or
                                 * the name of a variable. NULL if the 'index'
                                 * parameter is >= 0 */
    Tcl_Obj *part2Ptr,          /* If non-NULL, gives the name of an element
                                 * in the array part1. */
    Tcl_Obj *newValuePtr,       /* New value for variable. */
    const int flags,            /* OR-ed combination of TCL_GLOBAL_ONLY, and
                                 * TCL_LEAVE_ERR_MSG bits. */
    int index)                  /* Index of local var where part1 is to be
                                 * found. */
{
    Interp *iPtr = (Interp *) interp;
    Tcl_Obj *oldValuePtr;
    Tcl_Obj *resultPtr = NULL;
    int result;

    /*
     * If the variable is in a hashtable and its hPtr field is NULL, then we
     * may have an upvar to an array element where the array was deleted or an
     * upvar to a namespace variable whose namespace was deleted. Generate an
     * error (allowing the variable to be reset would screw up our storage
     * allocation and is meaningless anyway).
     */

    if (TclIsVarDeadHash(varPtr)) {
        if (flags & TCL_LEAVE_ERR_MSG) {
            if (TclIsVarArrayElement(varPtr)) {
                TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "set",
                        danglingElement, index);
            } else {
                TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "set",
                        danglingVar, index);
            }
        }
        goto earlyError;
    }

    /*
     * It's an error to try to set an array variable itself.
     */

    if (TclIsVarArray(varPtr)) {
        if (flags & TCL_LEAVE_ERR_MSG) {
            TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "set", isArray,index);
        }
        goto earlyError;
    }

    /*
     * Invoke any read traces that have been set for the variable if it is
     * requested; this is only done in the core by the INST_LAPPEND_*
     * instructions.
     */

    if ((flags & TCL_TRACE_READS) && ((varPtr->flags & VAR_TRACED_READ)
            || (arrayPtr && (arrayPtr->flags & VAR_TRACED_READ)))) {
        if (TCL_ERROR == TclObjCallVarTraces(iPtr, arrayPtr, varPtr,
                part1Ptr, part2Ptr,
                TCL_TRACE_READS, (flags & TCL_LEAVE_ERR_MSG), index)) {
            goto earlyError;
        }
    }

    /*
     * Set the variable's new value. If appending, append the new value to the
     * variable, either as a list element or as a string. Also, if appending,
     * then if the variable's old value is unshared we can modify it directly,
     * otherwise we must create a new copy to modify: this is "copy on write".
     */

    oldValuePtr = varPtr->value.objPtr;
    if (flags & TCL_LIST_ELEMENT && !(flags & TCL_APPEND_VALUE)) {
        varPtr->value.objPtr = NULL;
    }
    if (flags & (TCL_APPEND_VALUE|TCL_LIST_ELEMENT)) {
#if 0
        /*
         * Can't happen now!
         */

        if (TclIsVarUndefined(varPtr) && (oldValuePtr != NULL)) {
            TclDecrRefCount(oldValuePtr);       /* Discard old value. */
            varPtr->value.objPtr = NULL;
            oldValuePtr = NULL;
        }
#endif
        if (flags & TCL_LIST_ELEMENT) {         /* Append list element. */
            if (oldValuePtr == NULL) {
                TclNewObj(oldValuePtr);
                varPtr->value.objPtr = oldValuePtr;
                Tcl_IncrRefCount(oldValuePtr);  /* Since var is referenced. */
            } else if (Tcl_IsShared(oldValuePtr)) {
                varPtr->value.objPtr = Tcl_DuplicateObj(oldValuePtr);
                TclDecrRefCount(oldValuePtr);
                oldValuePtr = varPtr->value.objPtr;
                Tcl_IncrRefCount(oldValuePtr);  /* Since var is referenced. */
            }
            result = Tcl_ListObjAppendElement(interp, oldValuePtr,
                    newValuePtr);
            if (result != TCL_OK) {
                goto earlyError;
            }
        } else {                                /* Append string. */
            /*
             * We append newValuePtr's bytes but don't change its ref count.
             */

            if (oldValuePtr == NULL) {
                varPtr->value.objPtr = newValuePtr;
                Tcl_IncrRefCount(newValuePtr);
            } else {
                if (Tcl_IsShared(oldValuePtr)) {        /* Append to copy. */
                    varPtr->value.objPtr = Tcl_DuplicateObj(oldValuePtr);
                    TclDecrRefCount(oldValuePtr);
                    oldValuePtr = varPtr->value.objPtr;
                    Tcl_IncrRefCount(oldValuePtr);      /* Since var is ref */
                }
                Tcl_AppendObjToObj(oldValuePtr, newValuePtr);
            }
        }
    } else if (newValuePtr != oldValuePtr) {
        /*
         * In this case we are replacing the value, so we don't need to do
         * more than swap the objects.
         */

        varPtr->value.objPtr = newValuePtr;
        Tcl_IncrRefCount(newValuePtr);          /* Var is another ref. */
        if (oldValuePtr != NULL) {
            TclDecrRefCount(oldValuePtr);       /* Discard old value. */
        }
    }

    /*
     * Invoke any write traces for the variable.
     */

    if ((varPtr->flags & VAR_TRACED_WRITE)
            || (arrayPtr && (arrayPtr->flags & VAR_TRACED_WRITE))) {
        if (TCL_ERROR == TclObjCallVarTraces(iPtr, arrayPtr, varPtr, part1Ptr,
                part2Ptr, (flags & (TCL_GLOBAL_ONLY|TCL_NAMESPACE_ONLY))
                | TCL_TRACE_WRITES, (flags & TCL_LEAVE_ERR_MSG), index)) {
            goto cleanup;
        }
    }

    /*
     * Return the variable's value unless the variable was changed in some
     * gross way by a trace (e.g. it was unset and then recreated as an
     * array).
     */

    if (TclIsVarScalar(varPtr) && !TclIsVarUndefined(varPtr)) {
        return varPtr->value.objPtr;
    }

    /*
     * A trace changed the value in some gross way. Return an empty string
     * object.
     */

    resultPtr = iPtr->emptyObjPtr;

    /*
     * If the variable doesn't exist anymore and no-one's using it, then free
     * up the relevant structures and hash table entries.
     */

  cleanup:
    if (TclIsVarUndefined(varPtr)) {
        TclCleanupVar(varPtr, arrayPtr);
    }
    return resultPtr;

  earlyError:
    if (newValuePtr->refCount == 0) {
        Tcl_DecrRefCount(newValuePtr);
    }
    goto cleanup;
}

/*
 *----------------------------------------------------------------------
 *
 * TclIncrObjVar2 --
 *
 *      Given a two-part variable name, which may refer either to a scalar
 *      variable or an element of an array, increment the Tcl object value of
 *      the variable by a specified Tcl_Obj increment value.
 *
 * Results:
 *      Returns a pointer to the Tcl_Obj holding the new value of the
 *      variable. If the specified variable doesn't exist, or there is a clash
 *      in array usage, or an error occurs while executing variable traces,
 *      then NULL is returned and a message will be left in the interpreter's
 *      result.
 *
 * Side effects:
 *      The value of the given variable is incremented by the specified
 *      amount. If either the array or the entry didn't exist then a new
 *      variable is created. The ref count for the returned object is _not_
 *      incremented to reflect the returned reference; if you want to keep a
 *      reference to the object you must increment its ref count yourself.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
TclIncrObjVar2(
    Tcl_Interp *interp,         /* Command interpreter in which variable is to
                                 * be found. */
    Tcl_Obj *part1Ptr,          /* Points to an object holding the name of an
                                 * array (if part2 is non-NULL) or the name of
                                 * a variable. */
    Tcl_Obj *part2Ptr,          /* If non-null, points to an object holding
                                 * the name of an element in the array
                                 * part1Ptr. */
    Tcl_Obj *incrPtr,           /* Amount to be added to variable. */
    int flags)                  /* Various flags that tell how to incr value:
                                 * any of TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * TCL_APPEND_VALUE, TCL_LIST_ELEMENT,
                                 * TCL_LEAVE_ERR_MSG. */
{
    Var *varPtr, *arrayPtr;

    varPtr = TclObjLookupVarEx(interp, part1Ptr, part2Ptr, flags, "read",
            1, 1, &arrayPtr);
    if (varPtr == NULL) {
        Tcl_AddObjErrorInfo(interp,
                "\n    (reading value of variable to increment)", -1);
        return NULL;
    }
    return TclPtrIncrObjVar(interp, varPtr, arrayPtr, part1Ptr, part2Ptr,
            incrPtr, flags, -1);
}

/*
 *----------------------------------------------------------------------
 *
 * TclPtrIncrObjVar --
 *
 *      Given the pointers to a variable and possible containing array,
 *      increment the Tcl object value of the variable by a Tcl_Obj increment.
 *
 * Results:
 *      Returns a pointer to the Tcl_Obj holding the new value of the
 *      variable. If the specified variable doesn't exist, or there is a clash
 *      in array usage, or an error occurs while executing variable traces,
 *      then NULL is returned and a message will be left in the interpreter's
 *      result.
 *
 * Side effects:
 *      The value of the given variable is incremented by the specified
 *      amount. If either the array or the entry didn't exist then a new
 *      variable is created. The ref count for the returned object is _not_
 *      incremented to reflect the returned reference; if you want to keep a
 *      reference to the object you must increment its ref count yourself.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
TclPtrIncrObjVar(
    Tcl_Interp *interp,         /* Command interpreter in which variable is to
                                 * be found. */
    Var *varPtr,                /* Reference to the variable to set. */
    Var *arrayPtr,              /* Reference to the array containing the
                                 * variable, or NULL if the variable is a
                                 * scalar. */
    Tcl_Obj *part1Ptr,          /* Points to an object holding the name of an
                                 * array (if part2 is non-NULL) or the name of
                                 * a variable. */
    Tcl_Obj *part2Ptr,          /* If non-null, points to an object holding
                                 * the name of an element in the array
                                 * part1Ptr. */
    Tcl_Obj *incrPtr,           /* Increment value. */
/* TODO: Which of these flag values really make sense? */
    const int flags,            /* Various flags that tell how to incr value:
                                 * any of TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * TCL_APPEND_VALUE, TCL_LIST_ELEMENT,
                                 * TCL_LEAVE_ERR_MSG. */
    int index)                  /* Index into the local variable table of the
                                 * variable, or -1. Only used when part1Ptr is
                                 * NULL. */
{
    register Tcl_Obj *varValuePtr, *newValuePtr = NULL;
    int duplicated, code;

    if (TclIsVarInHash(varPtr)) {
        VarHashRefCount(varPtr)++;
    }
    varValuePtr = TclPtrGetVar(interp, varPtr, arrayPtr, part1Ptr, part2Ptr,
            flags, index);
    if (TclIsVarInHash(varPtr)) {
        VarHashRefCount(varPtr)--;
    }
    if (varValuePtr == NULL) {
        varValuePtr = Tcl_NewIntObj(0);
    }
    if (Tcl_IsShared(varValuePtr)) {
        duplicated = 1;
        varValuePtr = Tcl_DuplicateObj(varValuePtr);
    } else {
        duplicated = 0;
    }
    code = TclIncrObj(interp, varValuePtr, incrPtr);
    if (code == TCL_OK) {
        newValuePtr = TclPtrSetVar(interp, varPtr, arrayPtr, part1Ptr,
                part2Ptr, varValuePtr, flags, index);
    } else if (duplicated) {
        Tcl_DecrRefCount(varValuePtr);
    }
    return newValuePtr;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_UnsetVar --
 *
 *      Delete a variable, so that it may not be accessed anymore.
 *
 * Results:
 *      Returns TCL_OK if the variable was successfully deleted, TCL_ERROR if
 *      the variable can't be unset. In the event of an error, if the
 *      TCL_LEAVE_ERR_MSG flag is set then an error message is left in the
 *      interp's result.
 *
 * Side effects:
 *      If varName is defined as a local or global variable in interp, it is
 *      deleted.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_UnsetVar(
    Tcl_Interp *interp,         /* Command interpreter in which varName is to
                                 * be looked up. */
    const char *varName,        /* Name of a variable in interp. May be either
                                 * a scalar name or an array name or an
                                 * element in an array. */
    int flags)                  /* OR-ed combination of any of
                                 * TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY or
                                 * TCL_LEAVE_ERR_MSG. */
{
    return Tcl_UnsetVar2(interp, varName, NULL, flags);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_UnsetVar2 --
 *
 *      Delete a variable, given a 2-part name.
 *
 * Results:
 *      Returns TCL_OK if the variable was successfully deleted, TCL_ERROR if
 *      the variable can't be unset. In the event of an error, if the
 *      TCL_LEAVE_ERR_MSG flag is set then an error message is left in the
 *      interp's result.
 *
 * Side effects:
 *      If part1 and part2 indicate a local or global variable in interp, it
 *      is deleted. If part1 is an array name and part2 is NULL, then the
 *      whole array is deleted.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_UnsetVar2(
    Tcl_Interp *interp,         /* Command interpreter in which varName is to
                                 * be looked up. */
    const char *part1,          /* Name of variable or array. */
    const char *part2,          /* Name of element within array or NULL. */
    int flags)                  /* OR-ed combination of any of
                                 * TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * TCL_LEAVE_ERR_MSG. */
{
    int result;
    Tcl_Obj *part1Ptr, *part2Ptr = NULL;

    part1Ptr = Tcl_NewStringObj(part1, -1);
    Tcl_IncrRefCount(part1Ptr);
    if (part2) {
        part2Ptr = Tcl_NewStringObj(part2, -1);
        Tcl_IncrRefCount(part2Ptr);
    }

    /*
     * Filter to pass through only the flags this interface supports.
     */

    flags &= (TCL_GLOBAL_ONLY|TCL_NAMESPACE_ONLY|TCL_LEAVE_ERR_MSG);
    result = TclObjUnsetVar2(interp, part1Ptr, part2Ptr, flags);

    Tcl_DecrRefCount(part1Ptr);
    if (part2Ptr) {
        Tcl_DecrRefCount(part2Ptr);
    }
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * TclObjUnsetVar2 --
 *
 *      Delete a variable, given a 2-object name.
 *
 * Results:
 *      Returns TCL_OK if the variable was successfully deleted, TCL_ERROR if
 *      the variable can't be unset. In the event of an error, if the
 *      TCL_LEAVE_ERR_MSG flag is set then an error message is left in the
 *      interp's result.
 *
 * Side effects:
 *      If part1ptr and part2Ptr indicate a local or global variable in
 *      interp, it is deleted. If part1Ptr is an array name and part2Ptr is
 *      NULL, then the whole array is deleted.
 *
 *----------------------------------------------------------------------
 */

int
TclObjUnsetVar2(
    Tcl_Interp *interp,         /* Command interpreter in which varName is to
                                 * be looked up. */
    Tcl_Obj *part1Ptr,          /* Name of variable or array. */
    Tcl_Obj *part2Ptr,          /* Name of element within array or NULL. */
    int flags)                  /* OR-ed combination of any of
                                 * TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY,
                                 * TCL_LEAVE_ERR_MSG. */
{
    Var *varPtr;
    Interp *iPtr = (Interp *) interp;
    Var *arrayPtr;
    int result;

    varPtr = TclObjLookupVarEx(interp, part1Ptr, part2Ptr, flags, "unset",
            /*createPart1*/ 0, /*createPart2*/ 0, &arrayPtr);
    if (varPtr == NULL) {
        return TCL_ERROR;
    }

    result = (TclIsVarUndefined(varPtr)? TCL_ERROR : TCL_OK);

    /*
     * Keep the variable alive until we're done with it. We used to
     * increase/decrease the refCount for each operation, making it hard to
     * find [Bug 735335] - caused by unsetting the variable whose value was
     * the variable's name.
     */

    if (TclIsVarInHash(varPtr)) {
        VarHashRefCount(varPtr)++;
    }

    UnsetVarStruct(varPtr, arrayPtr, iPtr, part1Ptr, part2Ptr, flags);

    /*
     * It's an error to unset an undefined variable.
     */

    if (result != TCL_OK) {
        if (flags & TCL_LEAVE_ERR_MSG) {
            TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "unset",
                    ((arrayPtr == NULL) ? noSuchVar : noSuchElement), -1);
        }
    }

#if ENABLE_NS_VARNAME_CACHING
    /*
     * Try to avoid keeping the Var struct allocated due to a tclNsVarNameType
     * keeping a reference. This removes some additional exteriorisations of
     * [Bug 736729], but may be a good thing independently of the bug.
     */

    if (part1Ptr->typePtr == &tclNsVarNameType) {
        TclFreeIntRep(part1Ptr);
        part1Ptr->typePtr = NULL;
    }
#endif

    /*
     * Finally, if the variable is truly not in use then free up its Var
     * structure and remove it from its hash table, if any. The ref count of
     * its value object, if any, was decremented above.
     */

    if (TclIsVarInHash(varPtr)) {
        VarHashRefCount(varPtr)--;
        CleanupVar(varPtr, arrayPtr);
    }
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * UnsetVarStruct --
 *
 *      Unset and delete a variable. This does the internal work for
 *      TclObjUnsetVar2 and TclDeleteNamespaceVars, which call here for each
 *      variable to be unset and deleted.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If the arguments indicate a local or global variable in iPtr, it is
 *      unset and deleted.
 *
 *----------------------------------------------------------------------
 */

static void
UnsetVarStruct(
    Var *varPtr,
    Var *arrayPtr,
    Interp *iPtr,
    Tcl_Obj *part1Ptr,
    Tcl_Obj *part2Ptr,
    int flags)
{
    Var dummyVar;
    int traced = TclIsVarTraced(varPtr)
            || (arrayPtr && (arrayPtr->flags & VAR_TRACED_UNSET));

    if (arrayPtr && (arrayPtr->flags & VAR_SEARCH_ACTIVE)) {
        DeleteSearches(iPtr, arrayPtr);
    } else if (varPtr->flags & VAR_SEARCH_ACTIVE) {
        DeleteSearches(iPtr, varPtr);
    }

    /*
     * The code below is tricky, because of the possibility that a trace
     * function might try to access a variable being deleted. To handle this
     * situation gracefully, do things in three steps:
     * 1. Copy the contents of the variable to a dummy variable structure, and
     *    mark the original Var structure as undefined.
     * 2. Invoke traces and clean up the variable, using the dummy copy.
     * 3. If at the end of this the original variable is still undefined and
     *    has no outstanding references, then delete it (but it could have
     *    gotten recreated by a trace).
     */

    dummyVar = *varPtr;
    dummyVar.flags &= ~VAR_ALL_HASH;
    TclSetVarUndefined(varPtr);

    /*
     * Call trace functions for the variable being deleted. Then delete its
     * traces. Be sure to abort any other traces for the variable that are
     * still pending. Special tricks:
     * 1. We need to increment varPtr's refCount around this: TclCallVarTraces
     *    will use dummyVar so it won't increment varPtr's refCount itself.
     * 2. Turn off the VAR_TRACE_ACTIVE flag in dummyVar: we want to call
     *    unset traces even if other traces are pending.
     */

    if (traced) {
        VarTrace *tracePtr = NULL;
        Tcl_HashEntry *tPtr = NULL;

        if (TclIsVarTraced(&dummyVar)) {
            /*
             * Transfer any existing traces on var, IF there are unset traces.
             * Otherwise just delete them.
             */

            int isNew;
            Tcl_HashEntry *tPtr =
                    Tcl_FindHashEntry(&iPtr->varTraces, (char *) varPtr);

            tracePtr = Tcl_GetHashValue(tPtr);
            varPtr->flags &= ~VAR_ALL_TRACES;
            Tcl_DeleteHashEntry(tPtr);
            if (dummyVar.flags & VAR_TRACED_UNSET) {
                tPtr = Tcl_CreateHashEntry(&iPtr->varTraces,
                        (char *) &dummyVar, &isNew);
                Tcl_SetHashValue(tPtr, tracePtr);
            } else {
                tPtr = NULL;
            }
        }

        if ((dummyVar.flags & VAR_TRACED_UNSET)
                || (arrayPtr && (arrayPtr->flags & VAR_TRACED_UNSET))) {
            dummyVar.flags &= ~VAR_TRACE_ACTIVE;
            TclObjCallVarTraces(iPtr, arrayPtr, (Var *) &dummyVar,
                    part1Ptr, part2Ptr,
                    (flags & (TCL_GLOBAL_ONLY|TCL_NAMESPACE_ONLY))
                            | TCL_TRACE_UNSETS,
                    /* leaveErrMsg */ 0, -1);
            if (tPtr) {
                Tcl_DeleteHashEntry(tPtr);
            }
        }

        if (tracePtr) {
            ActiveVarTrace *activePtr;

            while (tracePtr) {
                VarTrace *prevPtr = tracePtr;

                tracePtr = tracePtr->nextPtr;
                Tcl_EventuallyFree((ClientData) prevPtr, TCL_DYNAMIC);
            }
            for (activePtr = iPtr->activeVarTracePtr;  activePtr != NULL;
                    activePtr = activePtr->nextPtr) {
                if (activePtr->varPtr == varPtr) {
                    activePtr->nextTracePtr = NULL;
                }
            }
            dummyVar.flags &= ~VAR_ALL_TRACES;
        }
    }

    if (TclIsVarScalar(&dummyVar) && (dummyVar.value.objPtr != NULL)) {
        /*
         * Decrement the ref count of the var's value.
         */

        Tcl_Obj *objPtr = dummyVar.value.objPtr;

        TclDecrRefCount(objPtr);
    } else if (TclIsVarArray(&dummyVar)) {
        /*
         * If the variable is an array, delete all of its elements. This must
         * be done after calling and deleting the traces on the array, above
         * (that's the way traces are defined). If the array name is not
         * present and is required for a trace on some element, it will be
         * computed at DeleteArray.
         */

        DeleteArray(iPtr, part1Ptr, (Var *) &dummyVar, (flags
                & (TCL_GLOBAL_ONLY|TCL_NAMESPACE_ONLY)) | TCL_TRACE_UNSETS);
    } else if (TclIsVarLink(&dummyVar)) {
        /*
         * For global/upvar variables referenced in procedures, decrement the
         * reference count on the variable referred to, and free the
         * referenced variable if it's no longer needed.
         */

        Var *linkPtr = dummyVar.value.linkPtr;

        if (TclIsVarInHash(linkPtr)) {
            VarHashRefCount(linkPtr)--;
            CleanupVar(linkPtr, NULL);
        }
    }

    /*
     * If the variable was a namespace variable, decrement its reference
     * count.
     */

    TclClearVarNamespaceVar(varPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_UnsetObjCmd --
 *
 *      This object-based function is invoked to process the "unset" Tcl
 *      command. See the user documentation for details on what it does.
 *
 * Results:
 *      A standard Tcl object result value.
 *
 * Side effects:
 *      See the user documentation.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
int
Tcl_UnsetObjCmd(
    ClientData dummy,           /* Not used. */
    Tcl_Interp *interp,         /* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    register int i, flags = TCL_LEAVE_ERR_MSG;
    register char *name;

    if (objc == 1) {
        /*
         * Do nothing if no arguments supplied, so as to match command
         * documentation.
         */

        return TCL_OK;
    }

    /*
     * Simple, restrictive argument parsing. The only options are -- and
     * -nocomplain (which must come first and be given exactly to be an
     * option).
     */

    i = 1;
    name = TclGetString(objv[i]);
    if (name[0] == '-') {
        if (strcmp("-nocomplain", name) == 0) {
            i++;
            if (i == objc) {
                return TCL_OK;
            }
            flags = 0;
            name = TclGetString(objv[i]);
        }
        if (strcmp("--", name) == 0) {
            i++;
        }
    }

    for (; i < objc; i++) {
        if ((TclObjUnsetVar2(interp, objv[i], NULL, flags) != TCL_OK)
                && (flags == TCL_LEAVE_ERR_MSG)) {
            return TCL_ERROR;
        }
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_AppendObjCmd --
 *
 *      This object-based function is invoked to process the "append" Tcl
 *      command. See the user documentation for details on what it does.
 *
 * Results:
 *      A standard Tcl object result value.
 *
 * Side effects:
 *      A variable's value may be changed.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
int
Tcl_AppendObjCmd(
    ClientData dummy,           /* Not used. */
    Tcl_Interp *interp,         /* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    Var *varPtr, *arrayPtr;
    register Tcl_Obj *varValuePtr = NULL;
                                /* Initialized to avoid compiler warning. */
    int i;

    if (objc < 2) {
        Tcl_WrongNumArgs(interp, 1, objv, "varName ?value value ...?");
        return TCL_ERROR;
    }

    if (objc == 2) {
        varValuePtr = Tcl_ObjGetVar2(interp, objv[1], NULL,TCL_LEAVE_ERR_MSG);
        if (varValuePtr == NULL) {
            return TCL_ERROR;
        }
    } else {
        varPtr = TclObjLookupVarEx(interp, objv[1], NULL, TCL_LEAVE_ERR_MSG,
                "set", /*createPart1*/ 1, /*createPart2*/ 1, &arrayPtr);
        if (varPtr == NULL) {
            return TCL_ERROR;
        }
        for (i=2 ; i<objc ; i++) {
            /*
             * Note that we do not need to increase the refCount of the Var
             * pointers: should a trace delete the variable, the return value
             * of TclPtrSetVar will be NULL, and we will not access the
             * variable again.
             */

            varValuePtr = TclPtrSetVar(interp, varPtr, arrayPtr, objv[1],
                    NULL, objv[i], TCL_APPEND_VALUE|TCL_LEAVE_ERR_MSG, -1);
            if (varValuePtr == NULL) {
                return TCL_ERROR;
            }
        }
    }
    Tcl_SetObjResult(interp, varValuePtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_LappendObjCmd --
 *
 *      This object-based function is invoked to process the "lappend" Tcl
 *      command. See the user documentation for details on what it does.
 *
 * Results:
 *      A standard Tcl object result value.
 *
 * Side effects:
 *      A variable's value may be changed.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
int
Tcl_LappendObjCmd(
    ClientData dummy,           /* Not used. */
    Tcl_Interp *interp,         /* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    Tcl_Obj *varValuePtr, *newValuePtr;
    int numElems, createdNewObj;
    Var *varPtr, *arrayPtr;
    int result;

    if (objc < 2) {
        Tcl_WrongNumArgs(interp, 1, objv, "varName ?value value ...?");
        return TCL_ERROR;
    }
    if (objc == 2) {
        newValuePtr = Tcl_ObjGetVar2(interp, objv[1], NULL, 0);
        if (newValuePtr == NULL) {
            /*
             * The variable doesn't exist yet. Just create it with an empty
             * initial value.
             */

            TclNewObj(varValuePtr);
            newValuePtr = Tcl_ObjSetVar2(interp, objv[1], NULL, varValuePtr,
                    TCL_LEAVE_ERR_MSG);
            if (newValuePtr == NULL) {
                return TCL_ERROR;
            }
        } else {
            result = TclListObjLength(interp, newValuePtr, &numElems);
            if (result != TCL_OK) {
                return result;
            }
        }
    } else {
        /*
         * We have arguments to append. We used to call Tcl_SetVar2 to append
         * each argument one at a time to ensure that traces were run for each
         * append step. We now append the arguments all at once because it's
         * faster. Note that a read trace and a write trace for the variable
         * will now each only be called once. Also, if the variable's old
         * value is unshared we modify it directly, otherwise we create a new
         * copy to modify: this is "copy on write".
         */

        createdNewObj = 0;

        /*
         * Protect the variable pointers around the TclPtrGetVar call
         * to insure that they remain valid even if the variable was undefined
         * and unused.
         */

        varPtr = TclObjLookupVarEx(interp, objv[1], NULL, TCL_LEAVE_ERR_MSG,
                "set", /*createPart1*/ 1, /*createPart2*/ 1, &arrayPtr);
        if (varPtr == NULL) {
            return TCL_ERROR;
        }
        if (TclIsVarInHash(varPtr)) {
            VarHashRefCount(varPtr)++;
        }
        if (arrayPtr && TclIsVarInHash(arrayPtr)) {
            VarHashRefCount(arrayPtr)++;
        }
        varValuePtr = TclPtrGetVar(interp, varPtr, arrayPtr, objv[1], NULL,
                TCL_LEAVE_ERR_MSG, -1);
        if (TclIsVarInHash(varPtr)) {
            VarHashRefCount(varPtr)--;
        }
        if (arrayPtr && TclIsVarInHash(arrayPtr)) {
            VarHashRefCount(arrayPtr)--;
        }

        if (varValuePtr == NULL) {
            /*
             * We couldn't read the old value: either the var doesn't yet
             * exist or it's an array element. If it's new, we will try to
             * create it with Tcl_ObjSetVar2 below.
             */

            TclNewObj(varValuePtr);
            createdNewObj = 1;
        } else if (Tcl_IsShared(varValuePtr)) {
            varValuePtr = Tcl_DuplicateObj(varValuePtr);
            createdNewObj = 1;
        }

        result = TclListObjLength(interp, varValuePtr, &numElems);
        if (result == TCL_OK) {
            result = Tcl_ListObjReplace(interp, varValuePtr, numElems, 0,
                    (objc-2), (objv+2));
        }
        if (result != TCL_OK) {
            if (createdNewObj) {
                TclDecrRefCount(varValuePtr); /* Free unneeded obj. */
            }
            return result;
        }

        /*
         * Now store the list object back into the variable. If there is an
         * error setting the new value, decrement its ref count if it was new
         * and we didn't create the variable.
         */

        newValuePtr = TclPtrSetVar(interp, varPtr, arrayPtr, objv[1], NULL,
                varValuePtr, TCL_LEAVE_ERR_MSG, -1);
        if (newValuePtr == NULL) {
            return TCL_ERROR;
        }
    }

    /*
     * Set the interpreter's object result to refer to the variable's value
     * object.
     */

    Tcl_SetObjResult(interp, newValuePtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_ArrayObjCmd --
 *
 *      This object-based function is invoked to process the "array" Tcl
 *      command. See the user documentation for details on what it does.
 *
 * Results:
 *      A standard Tcl result object.
 *
 * Side effects:
 *      See the user documentation.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
int
Tcl_ArrayObjCmd(
    ClientData dummy,           /* Not used. */
    Tcl_Interp *interp,         /* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    /*
     * The list of constants below should match the arrayOptions string array
     * below.
     */

    enum {
        ARRAY_ANYMORE, ARRAY_DONESEARCH, ARRAY_EXISTS, ARRAY_GET,
        ARRAY_NAMES, ARRAY_NEXTELEMENT, ARRAY_SET, ARRAY_SIZE,
        ARRAY_STARTSEARCH, ARRAY_STATISTICS, ARRAY_UNSET
    };
    static const char *arrayOptions[] = {
        "anymore", "donesearch", "exists", "get", "names", "nextelement",
        "set", "size", "startsearch", "statistics", "unset", NULL
    };

    Interp *iPtr = (Interp *) interp;
    Var *varPtr, *arrayPtr;
    Tcl_HashEntry *hPtr;
    Tcl_Obj *varNamePtr;
    int notArray;
    int index, result;

    if (objc < 3) {
        Tcl_WrongNumArgs(interp, 1, objv, "option arrayName ?arg ...?");
        return TCL_ERROR;
    }

    if (Tcl_GetIndexFromObj(interp, objv[1], arrayOptions, "option",
            0, &index) != TCL_OK) {
        return TCL_ERROR;
    }

    /*
     * Locate the array variable
     */

    varNamePtr = objv[2];
    varPtr = TclObjLookupVarEx(interp, varNamePtr, NULL, /*flags*/ 0,
            /*msg*/ 0, /*createPart1*/ 0, /*createPart2*/ 0, &arrayPtr);

    /*
     * Special array trace used to keep the env array in sync for array names,
     * array get, etc.
     */

    if (varPtr && (varPtr->flags & VAR_TRACED_ARRAY)
            && (TclIsVarArray(varPtr) || TclIsVarUndefined(varPtr))) {
        if (TclObjCallVarTraces(iPtr, arrayPtr, varPtr, varNamePtr, NULL,
                (TCL_LEAVE_ERR_MSG|TCL_NAMESPACE_ONLY|TCL_GLOBAL_ONLY|
                TCL_TRACE_ARRAY), /* leaveErrMsg */ 1, -1) == TCL_ERROR) {
            return TCL_ERROR;
        }
    }

    /*
     * Verify that it is indeed an array variable. This test comes after the
     * traces - the variable may actually become an array as an effect of said
     * traces.
     */

    notArray = 0;
    if ((varPtr == NULL) || !TclIsVarArray(varPtr)
            || TclIsVarUndefined(varPtr)) {
        notArray = 1;
    }

    switch (index) {
    case ARRAY_ANYMORE: {
        ArraySearch *searchPtr;

        if (objc != 4) {
            Tcl_WrongNumArgs(interp, 2, objv, "arrayName searchId");
            return TCL_ERROR;
        }
        if (notArray) {
            goto error;
        }
        searchPtr = ParseSearchId(interp, varPtr, varNamePtr, objv[3]);
        if (searchPtr == NULL) {
            return TCL_ERROR;
        }
        while (1) {
            Var *varPtr2;

            if (searchPtr->nextEntry != NULL) {
                varPtr2 = VarHashGetValue(searchPtr->nextEntry);
                if (!TclIsVarUndefined(varPtr2)) {
                    break;
                }
            }
            searchPtr->nextEntry = Tcl_NextHashEntry(&searchPtr->search);
            if (searchPtr->nextEntry == NULL) {
                Tcl_SetObjResult(interp, iPtr->execEnvPtr->constants[0]);
                return TCL_OK;
            }
        }
        Tcl_SetObjResult(interp, iPtr->execEnvPtr->constants[1]);
        break;
    }
    case ARRAY_DONESEARCH: {
        ArraySearch *searchPtr, *prevPtr;

        if (objc != 4) {
            Tcl_WrongNumArgs(interp, 2, objv, "arrayName searchId");
            return TCL_ERROR;
        }
        if (notArray) {
            goto error;
        }
        searchPtr = ParseSearchId(interp, varPtr, varNamePtr, objv[3]);
        if (searchPtr == NULL) {
            return TCL_ERROR;
        }
        hPtr = Tcl_FindHashEntry(&iPtr->varSearches,(char *) varPtr);
        if (searchPtr == Tcl_GetHashValue(hPtr)) {
            if (searchPtr->nextPtr) {
                Tcl_SetHashValue(hPtr, searchPtr->nextPtr);
            } else {
                varPtr->flags &= ~VAR_SEARCH_ACTIVE;
                Tcl_DeleteHashEntry(hPtr);
            }
        } else {
            for (prevPtr=Tcl_GetHashValue(hPtr) ;; prevPtr=prevPtr->nextPtr) {
                if (prevPtr->nextPtr == searchPtr) {
                    prevPtr->nextPtr = searchPtr->nextPtr;
                    break;
                }
            }
        }
        ckfree((char *) searchPtr);
        break;
    }
    case ARRAY_NEXTELEMENT: {
        ArraySearch *searchPtr;
        Tcl_HashEntry *hPtr;
        Var *varPtr2;

        if (objc != 4) {
            Tcl_WrongNumArgs(interp, 2, objv, "arrayName searchId");
            return TCL_ERROR;
        }
        if (notArray) {
            goto error;
        }
        searchPtr = ParseSearchId(interp, varPtr, varNamePtr, objv[3]);
        if (searchPtr == NULL) {
            return TCL_ERROR;
        }
        while (1) {
            hPtr = searchPtr->nextEntry;
            if (hPtr == NULL) {
                hPtr = Tcl_NextHashEntry(&searchPtr->search);
                if (hPtr == NULL) {
                    return TCL_OK;
                }
            } else {
                searchPtr->nextEntry = NULL;
            }
            varPtr2 = VarHashGetValue(hPtr);
            if (!TclIsVarUndefined(varPtr2)) {
                break;
            }
        }
        Tcl_SetObjResult(interp, VarHashGetKey(varPtr2));
        break;
    }
    case ARRAY_STARTSEARCH: {
        ArraySearch *searchPtr;
        int isNew;
        char *varName = TclGetString(varNamePtr);

        if (objc != 3) {
            Tcl_WrongNumArgs(interp, 2, objv, "arrayName");
            return TCL_ERROR;
        }
        if (notArray) {
            goto error;
        }
        searchPtr = (ArraySearch *) ckalloc(sizeof(ArraySearch));
        hPtr = Tcl_CreateHashEntry(&iPtr->varSearches,
                (char *) varPtr, &isNew);
        if (isNew) {
            searchPtr->id = 1;
            Tcl_AppendResult(interp, "s-1-", varName, NULL);
            varPtr->flags |= VAR_SEARCH_ACTIVE;
            searchPtr->nextPtr = NULL;
        } else {
            char string[TCL_INTEGER_SPACE];

            searchPtr->id = ((ArraySearch *) Tcl_GetHashValue(hPtr))->id + 1;
            TclFormatInt(string, searchPtr->id);
            Tcl_AppendResult(interp, "s-", string, "-", varName, NULL);
            searchPtr->nextPtr = Tcl_GetHashValue(hPtr);
        }
        searchPtr->varPtr = varPtr;
        searchPtr->nextEntry = VarHashFirstEntry(varPtr->value.tablePtr,
                &searchPtr->search);
        Tcl_SetHashValue(hPtr, searchPtr);
        break;
    }

    case ARRAY_EXISTS:
        if (objc != 3) {
            Tcl_WrongNumArgs(interp, 2, objv, "arrayName");
            return TCL_ERROR;
        }
        Tcl_SetObjResult(interp, iPtr->execEnvPtr->constants[!notArray]);
        break;
    case ARRAY_GET: {
        Tcl_HashSearch search;
        Var *varPtr2;
        char *pattern = NULL;
        char *name;
        Tcl_Obj *namePtr, *valuePtr, *nameLstPtr, *tmpResPtr, **namePtrPtr;
        int i, count;

        if ((objc != 3) && (objc != 4)) {
            Tcl_WrongNumArgs(interp, 2, objv, "arrayName ?pattern?");
            return TCL_ERROR;
        }
        if (notArray) {
            return TCL_OK;
        }
        if (objc == 4) {
            pattern = TclGetString(objv[3]);
        }

        /*
         * Store the array names in a new object.
         */

        TclNewObj(nameLstPtr);
        Tcl_IncrRefCount(nameLstPtr);
        if ((pattern != NULL) && TclMatchIsTrivial(pattern)) {
            varPtr2 = VarHashFindVar(varPtr->value.tablePtr, objv[3]);
            if (varPtr2 == NULL) {
                goto searchDone;
            }
            if (TclIsVarUndefined(varPtr2)) {
                goto searchDone;
            }
            result = Tcl_ListObjAppendElement(interp, nameLstPtr,
                    VarHashGetKey(varPtr2));
            if (result != TCL_OK) {
                TclDecrRefCount(nameLstPtr);
                return result;
            }
            goto searchDone;
        }
        for (varPtr2 = VarHashFirstVar(varPtr->value.tablePtr, &search);
                varPtr2; varPtr2 = VarHashNextVar(&search)) {
            if (TclIsVarUndefined(varPtr2)) {
                continue;
            }
            namePtr = VarHashGetKey(varPtr2);
            name = TclGetString(namePtr);
            if ((objc == 4) && !Tcl_StringMatch(name, pattern)) {
                continue;       /* Element name doesn't match pattern. */
            }

            result = Tcl_ListObjAppendElement(interp, nameLstPtr, namePtr);
            if (result != TCL_OK) {
                TclDecrRefCount(nameLstPtr);
                return result;
            }
        }

    searchDone:
        /*
         * Make sure the Var structure of the array is not removed by a trace
         * while we're working.
         */

        if (TclIsVarInHash(varPtr)) {
            VarHashRefCount(varPtr)++;
        }

        /*
         * Get the array values corresponding to each element name.
         */

        TclNewObj(tmpResPtr);
        result = Tcl_ListObjGetElements(interp, nameLstPtr, &count,
                &namePtrPtr);
        if (result != TCL_OK) {
            goto errorInArrayGet;
        }

        for (i=0 ; i<count ; i++) {
            namePtr = *namePtrPtr++;
            valuePtr = Tcl_ObjGetVar2(interp, objv[2], namePtr,
                    TCL_LEAVE_ERR_MSG);
            if (valuePtr == NULL) {
                /*
                 * Some trace played a trick on us; we need to diagnose to
                 * adapt our behaviour: was the array element unset, or did
                 * the modification modify the complete array?
                 */

                if (TclIsVarArray(varPtr)) {
                    /*
                     * The array itself looks OK, the variable was undefined:
                     * forget it.
                     */

                    continue;
                } else {
                    result = TCL_ERROR;
                    goto errorInArrayGet;
                }
            }
            result = Tcl_DictObjPut(interp, tmpResPtr, namePtr, valuePtr);
            if (result != TCL_OK) {
                goto errorInArrayGet;
            }
        }
        if (TclIsVarInHash(varPtr)) {
            VarHashRefCount(varPtr)--;
        }
        Tcl_SetObjResult(interp, tmpResPtr);
        TclDecrRefCount(nameLstPtr);
        break;

    errorInArrayGet:
        if (TclIsVarInHash(varPtr)) {
            VarHashRefCount(varPtr)--;
        }
        TclDecrRefCount(nameLstPtr);
        TclDecrRefCount(tmpResPtr);     /* Free unneeded temp result. */
        return result;
    }
    case ARRAY_NAMES: {
        Tcl_HashSearch search;
        Var *varPtr2;
        char *pattern;
        char *name;
        Tcl_Obj *namePtr, *resultPtr, *patternPtr;
        int mode, matched = 0;
        static const char *options[] = {
            "-exact", "-glob", "-regexp", NULL
        };
        enum options { OPT_EXACT, OPT_GLOB, OPT_REGEXP };

        mode = OPT_GLOB;

        if ((objc < 3) || (objc > 5)) {
            Tcl_WrongNumArgs(interp, 2,objv, "arrayName ?mode? ?pattern?");
            return TCL_ERROR;
        }
        if (notArray) {
            return TCL_OK;
        }
        if (objc == 4) {
            patternPtr = objv[3];
            pattern = TclGetString(patternPtr);
        } else if (objc == 5) {
            patternPtr = objv[4];
            pattern = TclGetString(patternPtr);
            if (Tcl_GetIndexFromObj(interp, objv[3], options, "option", 0,
                    &mode) != TCL_OK) {
                return TCL_ERROR;
            }
        } else {
            patternPtr = NULL;
            pattern = NULL;
        }
        TclNewObj(resultPtr);
        if (((enum options) mode)==OPT_GLOB && pattern!=NULL &&
                TclMatchIsTrivial(pattern)) {
            varPtr2 = VarHashFindVar(varPtr->value.tablePtr, patternPtr);
            if ((varPtr2 != NULL) && !TclIsVarUndefined(varPtr2)) {
                result = Tcl_ListObjAppendElement(interp, resultPtr,
                        VarHashGetKey(varPtr2));
                if (result != TCL_OK) {
                    TclDecrRefCount(resultPtr);
                    return result;
                }
            }
            Tcl_SetObjResult(interp, resultPtr);
            return TCL_OK;
        }
        for (varPtr2=VarHashFirstVar(varPtr->value.tablePtr, &search);
                varPtr2!=NULL ; varPtr2=VarHashNextVar(&search)) {
            if (TclIsVarUndefined(varPtr2)) {
                continue;
            }
            namePtr = VarHashGetKey(varPtr2);
            name = TclGetString(namePtr);
            if (objc > 3) {
                switch ((enum options) mode) {
                case OPT_EXACT:
                    matched = (strcmp(name, pattern) == 0);
                    break;
                case OPT_GLOB:
                    matched = Tcl_StringMatch(name, pattern);
                    break;
                case OPT_REGEXP:
                    matched = Tcl_RegExpMatch(interp, name, pattern);
                    if (matched < 0) {
                        TclDecrRefCount(resultPtr);
                        return TCL_ERROR;
                    }
                    break;
                }
                if (matched == 0) {
                    continue;
                }
            }

            result = Tcl_ListObjAppendElement(interp, resultPtr, namePtr);
            if (result != TCL_OK) {
                TclDecrRefCount(namePtr);       /* Free unneeded name obj. */
                return result;
            }
        }
        Tcl_SetObjResult(interp, resultPtr);
        break;
    }
    case ARRAY_SET:
        if (objc != 4) {
            Tcl_WrongNumArgs(interp, 2, objv, "arrayName list");
            return TCL_ERROR;
        }
        return TclArraySet(interp, objv[2], objv[3]);
    case ARRAY_UNSET: {
        Tcl_HashSearch search;
        Var *varPtr2;
        char *pattern = NULL;

        if ((objc != 3) && (objc != 4)) {
            Tcl_WrongNumArgs(interp, 2, objv, "arrayName ?pattern?");
            return TCL_ERROR;
        }
        if (notArray) {
            return TCL_OK;
        }
        if (objc == 3) {
            /*
             * When no pattern is given, just unset the whole array.
             */

            if (TclObjUnsetVar2(interp, varNamePtr, NULL, 0) != TCL_OK) {
                return TCL_ERROR;
            }
        } else {
            pattern = TclGetString(objv[3]);
            if (TclMatchIsTrivial(pattern)) {
                varPtr2 = VarHashFindVar(varPtr->value.tablePtr, objv[3]);
                if (varPtr2 != NULL && !TclIsVarUndefined(varPtr2)) {
                    return TclObjUnsetVar2(interp, varNamePtr, objv[3], 0);
                }
                return TCL_OK;
            }
            for (varPtr2=VarHashFirstVar(varPtr->value.tablePtr, &search);
                    varPtr2!=NULL ; varPtr2=VarHashNextVar(&search)) {
                Tcl_Obj *namePtr;

                if (TclIsVarUndefined(varPtr2)) {
                    continue;
                }
                namePtr = VarHashGetKey(varPtr2);
                if (Tcl_StringMatch(TclGetString(namePtr), pattern) &&
                        TclObjUnsetVar2(interp, varNamePtr, namePtr,
                                0) != TCL_OK) {
                    return TCL_ERROR;
                }
            }
        }
        break;
    }

    case ARRAY_SIZE: {
        Tcl_HashSearch search;
        Var *varPtr2;
        int size;

        if (objc != 3) {
            Tcl_WrongNumArgs(interp, 2, objv, "arrayName");
            return TCL_ERROR;
        }
        size = 0;

        /*
         * Must iterate in order to get chance to check for present but
         * "undefined" entries.
         */

        if (!notArray) {
            for (varPtr2=VarHashFirstVar(varPtr->value.tablePtr, &search);
                    varPtr2!=NULL ; varPtr2=VarHashNextVar(&search)) {
                if (TclIsVarUndefined(varPtr2)) {
                    continue;
                }
                size++;
            }
        }
        Tcl_SetObjResult(interp, Tcl_NewIntObj(size));
        break;
    }

    case ARRAY_STATISTICS: {
        const char *stats;

        if (notArray) {
            goto error;
        }

        stats = Tcl_HashStats((Tcl_HashTable *) varPtr->value.tablePtr);
        if (stats != NULL) {
            Tcl_SetObjResult(interp, Tcl_NewStringObj(stats, -1));
            ckfree((void *)stats);
        } else {
            Tcl_SetResult(interp,"error reading array statistics",TCL_STATIC);
            return TCL_ERROR;
        }
        break;
    }
    }
    return TCL_OK;

  error:
    Tcl_AppendResult(interp, "\"", TclGetString(varNamePtr),
            "\" isn't an array", NULL);
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * TclArraySet --
 *
 *      Set the elements of an array. If there are no elements to set, create
 *      an empty array. This routine is used by the Tcl_ArrayObjCmd and by the
 *      TclSetupEnv routine.
 *
 * Results:
 *      A standard Tcl result object.
 *
 * Side effects:
 *      A variable will be created if one does not already exist.
 *
 *----------------------------------------------------------------------
 */

int
TclArraySet(
    Tcl_Interp *interp,         /* Current interpreter. */
    Tcl_Obj *arrayNameObj,      /* The array name. */
    Tcl_Obj *arrayElemObj)      /* The array elements list or dict. If this is
                                 * NULL, create an empty array. */
{
    Var *varPtr, *arrayPtr;
    int result, i;

    varPtr = TclObjLookupVarEx(interp, arrayNameObj, NULL,
            /*flags*/ TCL_LEAVE_ERR_MSG, /*msg*/ "set", /*createPart1*/ 1,
            /*createPart2*/ 1, &arrayPtr);
    if (varPtr == NULL) {
        return TCL_ERROR;
    }
    if (arrayPtr) {
        CleanupVar(varPtr, arrayPtr);
        TclObjVarErrMsg(interp, arrayNameObj, NULL, "set", needArray, -1);
        return TCL_ERROR;
    }

    if (arrayElemObj == NULL) {
        goto ensureArray;
    }

    /*
     * Install the contents of the dictionary or list into the array.
     */

    if (arrayElemObj->typePtr == &tclDictType) {
        Tcl_Obj *keyPtr, *valuePtr;
        Tcl_DictSearch search;
        int done;

        if (Tcl_DictObjSize(interp, arrayElemObj, &done) != TCL_OK) {
            return TCL_ERROR;
        }
        if (done == 0) {
            /*
             * Empty, so we'll just force the array to be properly existing
             * instead.
             */

            goto ensureArray;
        }

        /*
         * Don't need to look at result of Tcl_DictObjFirst as we've just
         * successfully used a dictionary operation on the same object.
         */

        for (Tcl_DictObjFirst(interp, arrayElemObj, &search,
                &keyPtr, &valuePtr, &done) ; !done ;
                Tcl_DictObjNext(&search, &keyPtr, &valuePtr, &done)) {
            /*
             * At this point, it would be nice if the key was directly usable
             * by the array. This isn't the case though.
             */

            Var *elemVarPtr = TclLookupArrayElement(interp, arrayNameObj,
                    keyPtr, TCL_LEAVE_ERR_MSG, "set", 1, 1, varPtr, -1);

            if ((elemVarPtr == NULL) ||
                    (TclPtrSetVar(interp, elemVarPtr, varPtr, arrayNameObj,
                    keyPtr, valuePtr, TCL_LEAVE_ERR_MSG, -1) == NULL)) {
                Tcl_DictObjDone(&search);
                return TCL_ERROR;
            }
        }
        return TCL_OK;
    } else {
        /*
         * Not a dictionary, so assume (and convert to, for backward-
         * -compatability reasons) a list.
         */

        int elemLen;
        Tcl_Obj **elemPtrs, *copyListObj;

        result = TclListObjGetElements(interp, arrayElemObj,
                &elemLen, &elemPtrs);
        if (result != TCL_OK) {
            return result;
        }
        if (elemLen & 1) {
            Tcl_SetObjResult(interp, Tcl_NewStringObj(
                    "list must have an even number of elements", -1));
            return TCL_ERROR;
        }
        if (elemLen == 0) {
            goto ensureArray;
        }

        /*
         * We needn't worry about traces invalidating arrayPtr: should that be
         * the case, TclPtrSetVar will return NULL so that we break out of the
         * loop and return an error.
         */

        copyListObj = TclListObjCopy(NULL, arrayElemObj);
        for (i=0 ; i<elemLen ; i+=2) {
            Var *elemVarPtr = TclLookupArrayElement(interp, arrayNameObj,
                    elemPtrs[i], TCL_LEAVE_ERR_MSG, "set", 1, 1, varPtr, -1);

            if ((elemVarPtr == NULL) ||
                    (TclPtrSetVar(interp, elemVarPtr, varPtr, arrayNameObj,
                    elemPtrs[i],elemPtrs[i+1],TCL_LEAVE_ERR_MSG,-1) == NULL)){
                result = TCL_ERROR;
                break;
            }
        }
        Tcl_DecrRefCount(copyListObj);
        return result;
    }

    /*
     * The list is empty make sure we have an array, or create one if
     * necessary.
     */

  ensureArray:
    if (varPtr != NULL) {
        if (TclIsVarArray(varPtr)) {
            /*
             * Already an array, done.
             */

            return TCL_OK;
        }
        if (TclIsVarArrayElement(varPtr) || !TclIsVarUndefined(varPtr)) {
            /*
             * Either an array element, or a scalar: lose!
             */

            TclObjVarErrMsg(interp, arrayNameObj, NULL, "array set",
                    needArray, -1);
            return TCL_ERROR;
        }
    }
    TclSetVarArray(varPtr);
    varPtr->value.tablePtr = (TclVarHashTable *)
            ckalloc(sizeof(TclVarHashTable));
    TclInitVarHashTable(varPtr->value.tablePtr, TclGetVarNsPtr(varPtr));
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ObjMakeUpvar --
 *
 *      This function does all of the work of the "global" and "upvar"
 *      commands.
 *
 * Results:
 *      A standard Tcl completion code. If an error occurs then an error
 *      message is left in iPtr->result.
 *
 * Side effects:
 *      The variable given by myName is linked to the variable in framePtr
 *      given by otherP1 and otherP2, so that references to myName are
 *      redirected to the other variable like a symbolic link.
 *
 *----------------------------------------------------------------------
 */

static int
ObjMakeUpvar(
    Tcl_Interp *interp,         /* Interpreter containing variables. Used for
                                 * error messages, too. */
    CallFrame *framePtr,        /* Call frame containing "other" variable.
                                 * NULL means use global :: context. */
    Tcl_Obj *otherP1Ptr,
    const char *otherP2,        /* Two-part name of variable in framePtr. */
    const int otherFlags,       /* 0, TCL_GLOBAL_ONLY or TCL_NAMESPACE_ONLY:
                                 * indicates scope of "other" variable. */
    Tcl_Obj *myNamePtr,         /* Name of variable which will refer to
                                 * otherP1/otherP2. Must be a scalar. */
    int myFlags,                /* 0, TCL_GLOBAL_ONLY or TCL_NAMESPACE_ONLY:
                                 * indicates scope of myName. */
    int index)                  /* If the variable to be linked is an indexed
                                 * scalar, this is its index. Otherwise, -1 */
{
    Interp *iPtr = (Interp *) interp;
    Var *otherPtr, *arrayPtr;
    CallFrame *varFramePtr;

    /*
     * Find "other" in "framePtr". If not looking up other in just the current
     * namespace, temporarily replace the current var frame pointer in the
     * interpreter in order to use TclObjLookupVar.
     */

    if (framePtr == NULL) {
        framePtr = iPtr->rootFramePtr;
    }

    varFramePtr = iPtr->varFramePtr;
    if (!(otherFlags & TCL_NAMESPACE_ONLY)) {
        iPtr->varFramePtr = framePtr;
    }
    otherPtr = TclObjLookupVar(interp, otherP1Ptr, otherP2,
            (otherFlags | TCL_LEAVE_ERR_MSG), "access",
            /*createPart1*/ 1, /*createPart2*/ 1, &arrayPtr);
    if (!(otherFlags & TCL_NAMESPACE_ONLY)) {
        iPtr->varFramePtr = varFramePtr;
    }
    if (otherPtr == NULL) {
        return TCL_ERROR;
    }

    /*
     * Check that we are not trying to create a namespace var linked to a
     * local variable in a procedure. If we allowed this, the local
     * variable in the shorter-lived procedure frame could go away leaving
     * the namespace var's reference invalid.
     */

    if (index < 0) {
        if (!(arrayPtr != NULL
                     ? (TclIsVarInHash(arrayPtr) && TclGetVarNsPtr(arrayPtr))
                     : (TclIsVarInHash(otherPtr) && TclGetVarNsPtr(otherPtr)))
                && ((myFlags & (TCL_GLOBAL_ONLY | TCL_NAMESPACE_ONLY))
                        || (varFramePtr == NULL)
                        || !HasLocalVars(varFramePtr)
                        || (strstr(TclGetString(myNamePtr), "::") != NULL))) {
            Tcl_AppendResult((Tcl_Interp *) iPtr, "bad variable name \"",
                    TclGetString(myNamePtr), "\": upvar won't create "
                    "namespace variable that refers to procedure variable",
                    NULL);
            return TCL_ERROR;
        }
    }

    return TclPtrObjMakeUpvar(interp, otherPtr, myNamePtr, myFlags, index);
}

/*
 *----------------------------------------------------------------------
 *
 * TclPtrMakeUpvar --
 *
 *      This procedure does all of the work of the "global" and "upvar"
 *      commands.
 *
 * Results:
 *      A standard Tcl completion code. If an error occurs then an error
 *      message is left in iPtr->result.
 *
 * Side effects:
 *      The variable given by myName is linked to the variable in framePtr
 *      given by otherP1 and otherP2, so that references to myName are
 *      redirected to the other variable like a symbolic link.
 *
 *----------------------------------------------------------------------
 */

int
TclPtrMakeUpvar(
    Tcl_Interp *interp,         /* Interpreter containing variables. Used for
                                 * error messages, too. */
    Var *otherPtr,              /* Pointer to the variable being linked-to. */
    const char *myName,         /* Name of variable which will refer to
                                 * otherP1/otherP2. Must be a scalar. */
    int myFlags,                /* 0, TCL_GLOBAL_ONLY or TCL_NAMESPACE_ONLY:
                                 * indicates scope of myName. */
    int index)                  /* If the variable to be linked is an indexed
                                 * scalar, this is its index. Otherwise, -1 */
{
    Tcl_Obj *myNamePtr;
    int result;

    if (myName) {
        myNamePtr = Tcl_NewStringObj(myName, -1);
        Tcl_IncrRefCount(myNamePtr);
    } else {
        myNamePtr = NULL;
    }
    result = TclPtrObjMakeUpvar(interp, otherPtr, myNamePtr, myFlags, index);
    if (myNamePtr) {
        Tcl_DecrRefCount(myNamePtr);
    }
    return result;
}

int
TclPtrObjMakeUpvar(
    Tcl_Interp *interp,         /* Interpreter containing variables. Used for
                                 * error messages, too. */
    Var *otherPtr,              /* Pointer to the variable being linked-to. */
    Tcl_Obj *myNamePtr,         /* Name of variable which will refer to
                                 * otherP1/otherP2. Must be a scalar. */
    int myFlags,                /* 0, TCL_GLOBAL_ONLY or TCL_NAMESPACE_ONLY:
                                 * indicates scope of myName. */
    int index)                  /* If the variable to be linked is an indexed
                                 * scalar, this is its index. Otherwise, -1 */
{
    Interp *iPtr = (Interp *) interp;
    CallFrame *varFramePtr = iPtr->varFramePtr;
    const char *errMsg, *p, *myName;
    Var *varPtr;

    if (index >= 0) {
        if (!HasLocalVars(varFramePtr)) {
            Tcl_Panic("ObjMakeUpvar called with an index outside from a proc");
        }
        varPtr = (Var *) &(varFramePtr->compiledLocals[index]);
        myNamePtr = localName(iPtr->varFramePtr, index);
        myName = myNamePtr? TclGetString(myNamePtr) : NULL;
    } else {
        /*
         * Do not permit the new variable to look like an array reference, as
         * it will not be reachable in that case [Bug 600812, TIP 184]. The
         * "definition" of what "looks like an array reference" is consistent
         * (and must remain consistent) with the code in TclObjLookupVar().
         */

        myName = TclGetString(myNamePtr);
        p = strstr(myName, "(");
        if (p != NULL) {
            p += strlen(p)-1;
            if (*p == ')') {
                /*
                 * myName looks like an array reference.
                 */

                Tcl_AppendResult((Tcl_Interp *) iPtr, "bad variable name \"",
                        myName, "\": upvar won't create a scalar variable "
                        "that looks like an array element", NULL);
                return TCL_ERROR;
            }
        }

        /*
         * Lookup and eventually create the new variable. Set the flag bit
         * AVOID_RESOLVERS to indicate the special resolution rules for upvar
         * purposes:
         *   - Bug #696893 - variable is either proc-local or in the current
         *     namespace; never follow the second (global) resolution path.
         *   - Bug #631741 - do not use special namespace or interp resolvers.
         */

        varPtr = TclLookupSimpleVar(interp, myNamePtr,
                myFlags|AVOID_RESOLVERS, /* create */ 1, &errMsg, &index);
        if (varPtr == NULL) {
            TclObjVarErrMsg(interp, myNamePtr, NULL, "create", errMsg, -1);
            return TCL_ERROR;
        }
    }

    if (varPtr == otherPtr) {
        Tcl_SetResult((Tcl_Interp *) iPtr,
                "can't upvar from variable to itself", TCL_STATIC);
        return TCL_ERROR;
    }

    if (TclIsVarTraced(varPtr)) {
        Tcl_AppendResult((Tcl_Interp *) iPtr, "variable \"", myName,
                "\" has traces: can't use for upvar", NULL);
        return TCL_ERROR;
    } else if (!TclIsVarUndefined(varPtr)) {
        /*
         * The variable already existed. Make sure this variable "varPtr"
         * isn't the same as "otherPtr" (avoid circular links). Also, if it's
         * not an upvar then it's an error. If it is an upvar, then just
         * disconnect it from the thing it currently refers to.
         */

        if (TclIsVarLink(varPtr)) {
            Var *linkPtr = varPtr->value.linkPtr;
            if (linkPtr == otherPtr) {
                return TCL_OK;
            }
            if (TclIsVarInHash(linkPtr)) {
                VarHashRefCount(linkPtr)--;
                if (TclIsVarUndefined(linkPtr)) {
                    CleanupVar(linkPtr, NULL);
                }
            }
        } else {
            Tcl_AppendResult((Tcl_Interp *) iPtr, "variable \"", myName,
                    "\" already exists", NULL);
            return TCL_ERROR;
        }
    }
    TclSetVarLink(varPtr);
    varPtr->value.linkPtr = otherPtr;
    if (TclIsVarInHash(otherPtr)) {
        VarHashRefCount(otherPtr)++;
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_UpVar --
 *
 *      This function links one variable to another, just like the "upvar"
 *      command.
 *
 * Results:
 *      A standard Tcl completion code. If an error occurs then an error
 *      message is left in the interp's result.
 *
 * Side effects:
 *      The variable in frameName whose name is given by varName becomes
 *      accessible under the name localName, so that references to localName
 *      are redirected to the other variable like a symbolic link.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_UpVar(
    Tcl_Interp *interp,         /* Command interpreter in which varName is to
                                 * be looked up. */
    const char *frameName,      /* Name of the frame containing the source
                                 * variable, such as "1" or "#0". */
    const char *varName,        /* Name of a variable in interp to link to.
                                 * May be either a scalar name or an element
                                 * in an array. */
    const char *localName,      /* Name of link variable. */
    int flags)                  /* 0, TCL_GLOBAL_ONLY or TCL_NAMESPACE_ONLY:
                                 * indicates scope of localName. */
{
    return Tcl_UpVar2(interp, frameName, varName, NULL, localName, flags);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_UpVar2 --
 *
 *      This function links one variable to another, just like the "upvar"
 *      command.
 *
 * Results:
 *      A standard Tcl completion code. If an error occurs then an error
 *      message is left in the interp's result.
 *
 * Side effects:
 *      The variable in frameName whose name is given by part1 and part2
 *      becomes accessible under the name localName, so that references to
 *      localName are redirected to the other variable like a symbolic link.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_UpVar2(
    Tcl_Interp *interp,         /* Interpreter containing variables. Used for
                                 * error messages too. */
    const char *frameName,      /* Name of the frame containing the source
                                 * variable, such as "1" or "#0". */
    const char *part1,
    const char *part2,          /* Two parts of source variable name to link
                                 * to. */
    const char *localName,      /* Name of link variable. */
    int flags)                  /* 0, TCL_GLOBAL_ONLY or TCL_NAMESPACE_ONLY:
                                 * indicates scope of localName. */
{
    int result;
    CallFrame *framePtr;
    Tcl_Obj *part1Ptr, *localNamePtr;

    if (TclGetFrame(interp, frameName, &framePtr) == -1) {
        return TCL_ERROR;
    }

    part1Ptr = Tcl_NewStringObj(part1, -1);
    Tcl_IncrRefCount(part1Ptr);
    localNamePtr = Tcl_NewStringObj(localName, -1);
    Tcl_IncrRefCount(localNamePtr);

    result = ObjMakeUpvar(interp, framePtr, part1Ptr, part2, 0,
            localNamePtr, flags, -1);
    Tcl_DecrRefCount(part1Ptr);
    Tcl_DecrRefCount(localNamePtr);
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetVariableFullName --
 *
 *      Given a Tcl_Var token returned by Tcl_FindNamespaceVar, this function
 *      appends to an object the namespace variable's full name, qualified by
 *      a sequence of parent namespace names.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The variable's fully-qualified name is appended to the string
 *      representation of objPtr.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_GetVariableFullName(
    Tcl_Interp *interp,         /* Interpreter containing the variable. */
    Tcl_Var variable,           /* Token for the variable returned by a
                                 * previous call to Tcl_FindNamespaceVar. */
    Tcl_Obj *objPtr)            /* Points to the object onto which the
                                 * variable's full name is appended. */
{
    Interp *iPtr = (Interp *) interp;
    register Var *varPtr = (Var *) variable;
    Tcl_Obj *namePtr;
    Namespace *nsPtr;

    /*
     * Add the full name of the containing namespace (if any), followed by the
     * "::" separator, then the variable name.
     */

    if (varPtr) {
        if (!TclIsVarArrayElement(varPtr)) {
            nsPtr = TclGetVarNsPtr(varPtr);
            if (nsPtr) {
                Tcl_AppendToObj(objPtr, nsPtr->fullName, -1);
                if (nsPtr != iPtr->globalNsPtr) {
                    Tcl_AppendToObj(objPtr, "::", 2);
                }
            }
            if (TclIsVarInHash(varPtr)) {
                if (!TclIsVarDeadHash(varPtr)) {
                    namePtr = VarHashGetKey(varPtr);
                    Tcl_AppendObjToObj(objPtr, namePtr);
                }
            } else if (iPtr->varFramePtr->procPtr) {
                int index = varPtr - iPtr->varFramePtr->compiledLocals;

                if (index < iPtr->varFramePtr->numCompiledLocals) {
                    namePtr = localName(iPtr->varFramePtr, index);
                    Tcl_AppendObjToObj(objPtr, namePtr);
                }
            }
        }
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GlobalObjCmd --
 *
 *      This object-based function is invoked to process the "global" Tcl
 *      command. See the user documentation for details on what it does.
 *
 * Results:
 *      A standard Tcl object result value.
 *
 * Side effects:
 *      See the user documentation.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_GlobalObjCmd(
    ClientData dummy,           /* Not used. */
    Tcl_Interp *interp,         /* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    Interp *iPtr = (Interp *) interp;
    register Tcl_Obj *objPtr, *tailPtr;
    char *varName;
    register char *tail;
    int result, i;

    if (objc < 2) {
        Tcl_WrongNumArgs(interp, 1, objv, "varName ?varName ...?");
        return TCL_ERROR;
    }

    /*
     * If we are not executing inside a Tcl procedure, just return.
     */

    if (!HasLocalVars(iPtr->varFramePtr)) {
        return TCL_OK;
    }

    for (i=1 ; i<objc ; i++) {
        /*
         * Make a local variable linked to its counterpart in the global ::
         * namespace.
         */

        objPtr = objv[i];
        varName = TclGetString(objPtr);

        /*
         * The variable name might have a scope qualifier, but the name for
         * the local "link" variable must be the simple name at the tail.
         */

        for (tail=varName ; *tail!='\0' ; tail++) {
            /* empty body */
        }
        while ((tail > varName) && ((*tail != ':') || (*(tail-1) != ':'))) {
            tail--;
        }
        if ((*tail == ':') && (tail > varName)) {
            tail++;
        }

        if (tail == varName) {
            tailPtr = objPtr;
        } else {
            tailPtr = Tcl_NewStringObj(tail, -1);
            Tcl_IncrRefCount(tailPtr);
        }

        /*
         * Link to the variable "varName" in the global :: namespace.
         */

        result = ObjMakeUpvar(interp, NULL, objPtr, NULL,
                TCL_GLOBAL_ONLY, /*myName*/ tailPtr, /*myFlags*/ 0, -1);

        if (tail != varName) {
            Tcl_DecrRefCount(tailPtr);
        }

        if (result != TCL_OK) {
            return result;
        }
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_VariableObjCmd --
 *
 *      Invoked to implement the "variable" command that creates one or more
 *      global variables. Handles the following syntax:
 *
 *          variable ?name value...? name ?value?
 *
 *      One or more variables can be created. The variables are initialized
 *      with the specified values. The value for the last variable is
 *      optional.
 *
 *      If the variable does not exist, it is created and given the optional
 *      value. If it already exists, it is simply set to the optional value.
 *      Normally, "name" is an unqualified name, so it is created in the
 *      current namespace. If it includes namespace qualifiers, it can be
 *      created in another namespace.
 *
 *      If the variable command is executed inside a Tcl procedure, it creates
 *      a local variable linked to the newly-created namespace variable.
 *
 * Results:
 *      Returns TCL_OK if the variable is found or created. Returns TCL_ERROR
 *      if anything goes wrong.
 *
 * Side effects:
 *      If anything goes wrong, this function returns an error message as the
 *      result in the interpreter's result object.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_VariableObjCmd(
    ClientData dummy,           /* Not used. */
    Tcl_Interp *interp,         /* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    Interp *iPtr = (Interp *) interp;
    char *varName, *tail, *cp;
    Var *varPtr, *arrayPtr;
    Tcl_Obj *varValuePtr;
    int i, result;
    Tcl_Obj *varNamePtr, *tailPtr;

    if (objc < 2) {
        Tcl_WrongNumArgs(interp, 1, objv, "?name value...? name ?value?");
        return TCL_ERROR;
    }

    for (i=1 ; i<objc ; i+=2) {
        /*
         * Look up each variable in the current namespace context, creating it
         * if necessary.
         */

        varNamePtr = objv[i];
        varName = TclGetString(varNamePtr);
        varPtr = TclObjLookupVarEx(interp, varNamePtr, NULL,
                (TCL_NAMESPACE_ONLY | TCL_LEAVE_ERR_MSG), "define",
                /*createPart1*/ 1, /*createPart2*/ 0, &arrayPtr);

        if (arrayPtr != NULL) {
            /*
             * Variable cannot be an element in an array. If arrayPtr is
             * non-NULL, it is, so throw up an error and return.
             */

            TclObjVarErrMsg(interp, varNamePtr, NULL, "define",
                    isArrayElement, -1);
            return TCL_ERROR;
        }

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

        /*
         * Mark the variable as a namespace variable and increment its
         * reference count so that it will persist until its namespace is
         * destroyed or until the variable is unset.
         */

        TclSetVarNamespaceVar(varPtr);

        /*
         * If a value was specified, set the variable to that value.
         * Otherwise, if the variable is new, leave it undefined. (If the
         * variable already exists and no value was specified, leave its value
         * unchanged; just create the local link if we're in a Tcl procedure).
         */

        if (i+1 < objc) {       /* A value was specified. */
            varValuePtr = TclPtrSetVar(interp, varPtr, arrayPtr, varNamePtr,
                    NULL, objv[i+1], TCL_NAMESPACE_ONLY|TCL_LEAVE_ERR_MSG,-1);
            if (varValuePtr == NULL) {
                return TCL_ERROR;
            }
        }

        /*
         * If we are executing inside a Tcl procedure, create a local variable
         * linked to the new namespace variable "varName".
         */

        if (HasLocalVars(iPtr->varFramePtr)) {
            /*
             * varName might have a scope qualifier, but the name for the
             * local "link" variable must be the simple name at the tail.
             *
             * Locate tail in one pass: drop any prefix after two *or more*
             * consecutive ":" characters).
             */

            for (tail=cp=varName ; *cp!='\0' ;) {
                if (*cp++ == ':') {
                    while (*cp == ':') {
                        tail = ++cp;
                    }
                }
            }

            /*
             * Create a local link "tail" to the variable "varName" in the
             * current namespace.
             */

            if (tail == varName) {
                tailPtr = varNamePtr;
            } else {
                tailPtr = Tcl_NewStringObj(tail, -1);
                Tcl_IncrRefCount(tailPtr);
            }

            result = ObjMakeUpvar(interp, NULL, varNamePtr, /*otherP2*/ NULL,
                    /*otherFlags*/ TCL_NAMESPACE_ONLY,
                    /*myName*/ tailPtr, /*myFlags*/ 0, -1);

            if (tail != varName) {
                Tcl_DecrRefCount(tailPtr);
            }

            if (result != TCL_OK) {
                return result;
            }
        }
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_UpvarObjCmd --
 *
 *      This object-based function is invoked to process the "upvar" Tcl
 *      command. See the user documentation for details on what it does.
 *
 * Results:
 *      A standard Tcl object result value.
 *
 * Side effects:
 *      See the user documentation.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
int
Tcl_UpvarObjCmd(
    ClientData dummy,           /* Not used. */
    Tcl_Interp *interp,         /* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    CallFrame *framePtr;
    int result;

    if (objc < 3) {
    upvarSyntax:
        Tcl_WrongNumArgs(interp, 1, objv,
                "?level? otherVar localVar ?otherVar localVar ...?");
        return TCL_ERROR;
    }

    /*
     * Find the call frame containing each of the "other variables" to be
     * linked to.
     */

    result = TclObjGetFrame(interp, objv[1], &framePtr);
    if (result == -1) {
        return TCL_ERROR;
    }
    objc -= result+1;
    if ((objc & 1) != 0) {
        goto upvarSyntax;
    }
    objv += result+1;

    /*
     * Iterate over each (other variable, local variable) pair. Divide the
     * other variable name into two parts, then call MakeUpvar to do all the
     * work of linking it to the local variable.
     */

    for (; objc>0 ; objc-=2, objv+=2) {
        result = ObjMakeUpvar(interp, framePtr, /* othervarName */ objv[0],
                NULL, 0, /* myVarName */ objv[1], /*flags*/ 0, -1);
        if (result != TCL_OK) {
            return TCL_ERROR;
        }
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * SetArraySearchObj --
 *
 *      This function converts the given tcl object into one that has the
 *      "array search" internal type.
 *
 * Results:
 *      TCL_OK if the conversion succeeded, and TCL_ERROR if it failed (when
 *      an error message will be placed in the interpreter's result.)
 *
 * Side effects:
 *      Updates the internal type and representation of the object to make
 *      this an array-search object. See the tclArraySearchType declaration
 *      above for details of the internal representation.
 *
 *----------------------------------------------------------------------
 */

static int
SetArraySearchObj(
    Tcl_Interp *interp,
    Tcl_Obj *objPtr)
{
    char *string;
    char *end;
    int id;
    size_t offset;

    /*
     * Get the string representation. Make it up-to-date if necessary.
     */

    string = TclGetString(objPtr);

    /*
     * Parse the id into the three parts separated by dashes.
     */

    if ((string[0] != 's') || (string[1] != '-')) {
        goto syntax;
    }
    id = strtoul(string+2, &end, 10);
    if ((end == (string+2)) || (*end != '-')) {
        goto syntax;
    }

    /*
     * Can't perform value check in this context, so place reference to place
     * in string to use for the check in the object instead.
     */

    end++;
    offset = end - string;

    TclFreeIntRep(objPtr);
    objPtr->typePtr = &tclArraySearchType;
    objPtr->internalRep.twoPtrValue.ptr1 = INT2PTR(id);
    objPtr->internalRep.twoPtrValue.ptr2 = INT2PTR(offset);
    return TCL_OK;

  syntax:
    Tcl_AppendResult(interp, "illegal search identifier \"",string,"\"",NULL);
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseSearchId --
 *
 *      This function translates from a tcl object to a pointer to an active
 *      array search (if there is one that matches the string).
 *
 * Results:
 *      The return value is a pointer to the array search indicated by string,
 *      or NULL if there isn't one. If NULL is returned, the interp's result
 *      contains an error message.
 *
 * Side effects:
 *      The tcl object might have its internal type and representation
 *      modified.
 *
 *----------------------------------------------------------------------
 */

static ArraySearch *
ParseSearchId(
    Tcl_Interp *interp,         /* Interpreter containing variable. */
    const Var *varPtr,          /* Array variable search is for. */
    Tcl_Obj *varNamePtr,        /* Name of array variable that search is
                                 * supposed to be for. */
    Tcl_Obj *handleObj)         /* Object containing id of search. Must have
                                 * form "search-num-var" where "num" is a
                                 * decimal number and "var" is a variable
                                 * name. */
{
    Interp *iPtr = (Interp *) interp;
    register char *string;
    register size_t offset;
    int id;
    ArraySearch *searchPtr;
    char *varName = TclGetString(varNamePtr);

    /*
     * Parse the id.
     */

    if (Tcl_ConvertToType(interp, handleObj, &tclArraySearchType) != TCL_OK) {
        return NULL;
    }

    /*
     * Extract the information out of the Tcl_Obj.
     */

#if 1
    id = PTR2INT(handleObj->internalRep.twoPtrValue.ptr1);
    string = TclGetString(handleObj);
    offset = PTR2INT(handleObj->internalRep.twoPtrValue.ptr2);
#else
    id = (int)(((char *) handleObj->internalRep.twoPtrValue.ptr1) -
            ((char *) NULL));
    string = TclGetString(handleObj);
    offset = (((char *) handleObj->internalRep.twoPtrValue.ptr2) -
            ((char *) NULL));
#endif

    /*
     * This test cannot be placed inside the Tcl_Obj machinery, since it is
     * dependent on the variable context.
     */

    if (strcmp(string+offset, varName) != 0) {
        Tcl_AppendResult(interp, "search identifier \"", string,
                "\" isn't for variable \"", varName, "\"", NULL);
        goto badLookup;
    }

    /*
     * Search through the list of active searches on the interpreter to see if
     * the desired one exists.
     *
     * Note that we cannot store the searchPtr directly in the Tcl_Obj as that
     * would run into trouble when DeleteSearches() was called so we must scan
     * this list every time.
     */

    if (varPtr->flags & VAR_SEARCH_ACTIVE) {
        Tcl_HashEntry *hPtr =
                Tcl_FindHashEntry(&iPtr->varSearches, (char *) varPtr);

        for (searchPtr = (ArraySearch *) Tcl_GetHashValue(hPtr);
                searchPtr != NULL; searchPtr = searchPtr->nextPtr) {
            if (searchPtr->id == id) {
                return searchPtr;
            }
        }
    }
    Tcl_AppendResult(interp, "couldn't find search \"", string, "\"", NULL);
  badLookup:
    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ARRAYSEARCH", string, NULL);
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * DeleteSearches --
 *
 *      This function is called to free up all of the searches associated
 *      with an array variable.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Memory is released to the storage allocator.
 *
 *----------------------------------------------------------------------
 */

static void
DeleteSearches(
    Interp *iPtr,
    register Var *arrayVarPtr)  /* Variable whose searches are to be
                                 * deleted. */
{
    ArraySearch *searchPtr, *nextPtr;
    Tcl_HashEntry *sPtr;

    if (arrayVarPtr->flags & VAR_SEARCH_ACTIVE) {
        sPtr = Tcl_FindHashEntry(&iPtr->varSearches, (char *) arrayVarPtr);
        for (searchPtr = (ArraySearch *) Tcl_GetHashValue(sPtr);
                searchPtr != NULL; searchPtr = nextPtr) {
            nextPtr = searchPtr->nextPtr;
            ckfree((char *) searchPtr);
        }
        arrayVarPtr->flags &= ~VAR_SEARCH_ACTIVE;
        Tcl_DeleteHashEntry(sPtr);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TclDeleteNamespaceVars --
 *
 *      This function is called to recycle all the storage space associated
 *      with a namespace's table of variables.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Variables are deleted and trace functions are invoked, if any are
 *      declared.
 *
 *----------------------------------------------------------------------
 */

void
TclDeleteNamespaceVars(
    Namespace *nsPtr)
{
    TclVarHashTable *tablePtr = &nsPtr->varTable;
    Tcl_Interp *interp = nsPtr->interp;
    Interp *iPtr = (Interp *)interp;
    Tcl_HashSearch search;
    int flags = 0;
    Var *varPtr;

    /*
     * Determine what flags to pass to the trace callback functions.
     */

    if (nsPtr == iPtr->globalNsPtr) {
        flags = TCL_GLOBAL_ONLY;
    } else if (nsPtr == (Namespace *) TclGetCurrentNamespace(interp)) {
        flags = TCL_NAMESPACE_ONLY;
    }

    for (varPtr = VarHashFirstVar(tablePtr, &search);  varPtr != NULL;
            varPtr = VarHashFirstVar(tablePtr, &search)) {
        Tcl_Obj *objPtr = Tcl_NewObj();
        Tcl_IncrRefCount(objPtr);
        
        VarHashRefCount(varPtr)++;      /* Make sure we get to remove from
                                         * hash. */
        Tcl_GetVariableFullName(interp, (Tcl_Var) varPtr, objPtr);
        UnsetVarStruct(varPtr, NULL, iPtr, /* part1 */ objPtr,
                NULL, flags);
        Tcl_DecrRefCount(objPtr); /* free no longer needed obj */


        /*
         * Remove the variable from the table and force it undefined in case
         * an unset trace brought it back from the dead.
         */

        if (TclIsVarTraced(varPtr)) {
            Tcl_HashEntry *tPtr = Tcl_FindHashEntry(&iPtr->varTraces,
                    (char *) varPtr);
            VarTrace *tracePtr = (VarTrace *) Tcl_GetHashValue(tPtr);

            while (tracePtr) {
                VarTrace *prevPtr = tracePtr;

                tracePtr = tracePtr->nextPtr;
                Tcl_EventuallyFree((ClientData) prevPtr, TCL_DYNAMIC);
            }
            Tcl_DeleteHashEntry(tPtr);
            varPtr->flags &= ~VAR_ALL_TRACES;
        }
        VarHashRefCount(varPtr)--;
        VarHashDeleteEntry(varPtr);
    }
    VarHashDeleteTable(tablePtr);
}

/*
 *----------------------------------------------------------------------
 *
 * TclDeleteVars --
 *
 *      This function is called to recycle all the storage space associated
 *      with a table of variables. For this function to work correctly, it
 *      must not be possible for any of the variables in the table to be
 *      accessed from Tcl commands (e.g. from trace functions).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Variables are deleted and trace functions are invoked, if any are
 *      declared.
 *
 *----------------------------------------------------------------------
 */

void
TclDeleteVars(
    Interp *iPtr,               /* Interpreter to which variables belong. */
    TclVarHashTable *tablePtr)  /* Hash table containing variables to
                                 * delete. */
{
    Tcl_Interp *interp = (Tcl_Interp *) iPtr;
    Tcl_HashSearch search;
    register Var *varPtr;
    int flags;
    Namespace *currNsPtr = (Namespace *) TclGetCurrentNamespace(interp);

    /*
     * Determine what flags to pass to the trace callback functions.
     */

    flags = TCL_TRACE_UNSETS;
    if (tablePtr == &iPtr->globalNsPtr->varTable) {
        flags |= TCL_GLOBAL_ONLY;
    } else if (tablePtr == &currNsPtr->varTable) {
        flags |= TCL_NAMESPACE_ONLY;
    }

    for (varPtr = VarHashFirstVar(tablePtr, &search); varPtr != NULL;
            varPtr = VarHashNextVar(&search)) {
        /*
         * Lie about the validity of the hashtable entry. In this way the
         * variables will be deleted by VarHashDeleteTable.
         */

        VarHashInvalidateEntry(varPtr);
        UnsetVarStruct(varPtr, NULL, iPtr, VarHashGetKey(varPtr), NULL, flags);
    }
    VarHashDeleteTable(tablePtr);
}

/*
 *----------------------------------------------------------------------
 *
 * TclDeleteCompiledLocalVars --
 *
 *      This function is called to recycle storage space associated with the
 *      compiler-allocated array of local variables in a procedure call frame.
 *      This function resembles TclDeleteVars above except that each variable
 *      is stored in a call frame and not a hash table. For this function to
 *      work correctly, it must not be possible for any of the variable in the
 *      table to be accessed from Tcl commands (e.g. from trace functions).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Variables are deleted and trace functions are invoked, if any are
 *      declared.
 *
 *----------------------------------------------------------------------
 */

void
TclDeleteCompiledLocalVars(
    Interp *iPtr,               /* Interpreter to which variables belong. */
    CallFrame *framePtr)        /* Procedure call frame containing compiler-
                                 * assigned local variables to delete. */
{
    register Var *varPtr;
    int numLocals, i;
    Tcl_Obj **namePtrPtr;

    numLocals = framePtr->numCompiledLocals;
    varPtr = framePtr->compiledLocals;
    namePtrPtr = &localName(framePtr, 0);
    for (i=0 ; i<numLocals ; i++, namePtrPtr++, varPtr++) {
        UnsetVarStruct(varPtr, NULL, iPtr, *namePtrPtr, NULL,
                TCL_TRACE_UNSETS);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * DeleteArray --
 *
 *      This function is called to free up everything in an array variable.
 *      It's the caller's responsibility to make sure that the array is no
 *      longer accessible before this function is called.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      All storage associated with varPtr's array elements is deleted
 *      (including the array's hash table). Deletion trace functions for
 *      array elements are invoked, then deleted. Any pending traces for array
 *      elements are also deleted.
 *
 *----------------------------------------------------------------------
 */

static void
DeleteArray(
    Interp *iPtr,               /* Interpreter containing array. */
    Tcl_Obj *arrayNamePtr,      /* Name of array (used for trace callbacks),
                                 * or NULL if it is to be computed on
                                 * demand. */
    Var *varPtr,                /* Pointer to variable structure. */
    int flags)                  /* Flags to pass to TclCallVarTraces:
                                 * TCL_TRACE_UNSETS and sometimes
                                 * TCL_NAMESPACE_ONLY or TCL_GLOBAL_ONLY. */
{
    Tcl_HashSearch search;
    Tcl_HashEntry *tPtr;
    register Var *elPtr;
    ActiveVarTrace *activePtr;
    Tcl_Obj *objPtr;
    VarTrace *tracePtr;

    if (varPtr->flags & VAR_SEARCH_ACTIVE) {
        DeleteSearches(iPtr, varPtr);
    }
    for (elPtr = VarHashFirstVar(varPtr->value.tablePtr, &search);
            elPtr != NULL; elPtr = VarHashNextVar(&search)) {
        if (TclIsVarScalar(elPtr) && (elPtr->value.objPtr != NULL)) {
            objPtr = elPtr->value.objPtr;
            TclDecrRefCount(objPtr);
            elPtr->value.objPtr = NULL;
        }

        /*
         * Lie about the validity of the hashtable entry. In this way the
         * variables will be deleted by VarHashDeleteTable.
         */

        VarHashInvalidateEntry(elPtr);
        if (TclIsVarTraced(elPtr)) {
            /*
             * Compute the array name if it was not supplied.
             */

            if (elPtr->flags & VAR_TRACED_UNSET) {
                Tcl_Obj *elNamePtr = VarHashGetKey(elPtr);

                elPtr->flags &= ~VAR_TRACE_ACTIVE;
                TclObjCallVarTraces(iPtr, NULL, elPtr, arrayNamePtr,
                        elNamePtr, flags,/* leaveErrMsg */ 0, -1);
            }
            tPtr = Tcl_FindHashEntry(&iPtr->varTraces, (char *) elPtr);
            tracePtr = (VarTrace *) Tcl_GetHashValue(tPtr);
            while (tracePtr) {
                VarTrace *prevPtr = tracePtr;

                tracePtr = tracePtr->nextPtr;
                Tcl_EventuallyFree((ClientData) prevPtr, TCL_DYNAMIC);
            }
            Tcl_DeleteHashEntry(tPtr);
            elPtr->flags &= ~VAR_ALL_TRACES;
            for (activePtr = iPtr->activeVarTracePtr; activePtr != NULL;
                    activePtr = activePtr->nextPtr) {
                if (activePtr->varPtr == elPtr) {
                    activePtr->nextTracePtr = NULL;
                }
            }
        }
        TclSetVarUndefined(elPtr);

        /*
         * Even though array elements are not supposed to be namespace
         * variables, some combinations of [upvar] and [variable] may create
         * such beasts - see [Bug 604239]. This is necessary to avoid leaking
         * the corresponding Var struct, and is otherwise harmless.
         */

        TclClearVarNamespaceVar(elPtr);
    }
    VarHashDeleteTable(varPtr->value.tablePtr);
    ckfree((char *) varPtr->value.tablePtr);
}

/*
 *----------------------------------------------------------------------
 *
 * TclTclObjVarErrMsg --
 *
 *      Generate a reasonable error message describing why a variable
 *      operation failed.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The interp's result is set to hold a message identifying the variable
 *      given by part1 and part2 and describing why the variable operation
 *      failed.
 *
 *----------------------------------------------------------------------
 */

void
TclVarErrMsg(
    Tcl_Interp *interp,         /* Interpreter in which to record message. */
    const char *part1,
    const char *part2,          /* Variable's two-part name. */
    const char *operation,      /* String describing operation that failed,
                                 * e.g. "read", "set", or "unset". */
    const char *reason)         /* String describing why operation failed. */
{
    Tcl_Obj *part1Ptr = NULL, *part2Ptr = NULL;

    part1Ptr = Tcl_NewStringObj(part1, -1);
    Tcl_IncrRefCount(part1Ptr);
    if (part2) {
        part2Ptr = Tcl_NewStringObj(part2, -1);
        Tcl_IncrRefCount(part2Ptr);
    } else {
        part2 = NULL;
    }

    TclObjVarErrMsg(interp, part1Ptr, part2Ptr, operation, reason, -1);

    Tcl_DecrRefCount(part1Ptr);
    if (part2Ptr) {
        Tcl_DecrRefCount(part2Ptr);
    }
}

void
TclObjVarErrMsg(
    Tcl_Interp *interp,         /* Interpreter in which to record message. */
    Tcl_Obj *part1Ptr,          /* (may be NULL, if index >= 0) */
    Tcl_Obj *part2Ptr,          /* Variable's two-part name. */
    const char *operation,      /* String describing operation that failed,
                                 * e.g. "read", "set", or "unset". */
    const char *reason,         /* String describing why operation failed. */
    int index)                  /* Index into the local variable table of the
                                 * variable, or -1. Only used when part1Ptr is
                                 * NULL. */
{
    Tcl_ResetResult(interp);
    if (!part1Ptr) {
        part1Ptr = localName(((Interp *)interp)->varFramePtr, index);
    }
    Tcl_AppendResult(interp, "can't ", operation, " \"",
            TclGetString(part1Ptr), NULL);
    if (part2Ptr) {
        Tcl_AppendResult(interp, "(", TclGetString(part2Ptr), ")", NULL);
    }
    Tcl_AppendResult(interp, "\": ", reason, NULL);
}

/*
 *----------------------------------------------------------------------
 *
 * Internal functions for variable name object types --
 *
 *----------------------------------------------------------------------
 */

/*
 * Panic functions that should never be called in normal operation.
 */

static void
PanicOnUpdateVarName(
    Tcl_Obj *objPtr)
{
    Tcl_Panic("%s of type %s should not be called", "updateStringProc",
            objPtr->typePtr->name);
}

static int
PanicOnSetVarName(
    Tcl_Interp *interp,
    Tcl_Obj *objPtr)
{
    Tcl_Panic("%s of type %s should not be called", "setFromAnyProc",
            objPtr->typePtr->name);
    return TCL_ERROR;
}

/*
 * localVarName -
 *
 * INTERNALREP DEFINITION:
 *   ptrAndLongRep.ptr:   pointer to name obj in varFramePtr->localCache
 *                        or NULL if it is this same obj
 *   ptrAndLongRep.value: index into locals table
 */

static void
FreeLocalVarName(
    Tcl_Obj *objPtr)
{
    Tcl_Obj *namePtr = (Tcl_Obj *) objPtr->internalRep.ptrAndLongRep.ptr;
    if (namePtr) {
        Tcl_DecrRefCount(namePtr);
    }
}

static void
DupLocalVarName(
    Tcl_Obj *srcPtr,
    Tcl_Obj *dupPtr)
{
    Tcl_Obj *namePtr = srcPtr->internalRep.ptrAndLongRep.ptr;

    if (!namePtr) {
        namePtr = srcPtr;
    }
    dupPtr->internalRep.ptrAndLongRep.ptr = namePtr;
    Tcl_IncrRefCount(namePtr);

    dupPtr->internalRep.ptrAndLongRep.value =
            srcPtr->internalRep.ptrAndLongRep.value;
    dupPtr->typePtr = &localVarNameType;
}

#if ENABLE_NS_VARNAME_CACHING
/*
 * nsVarName -
 *
 * INTERNALREP DEFINITION:
 *   twoPtrValue.ptr1: pointer to the namespace containing the reference.
 *   twoPtrValue.ptr2: pointer to the corresponding Var
 */

static void
FreeNsVarName(
    Tcl_Obj *objPtr)
{
    register Var *varPtr = objPtr->internalRep.twoPtrValue.ptr2;

    if (TclIsVarInHash(varPtr)) {
        varPtr->refCount--;
        if (TclIsVarUndefined(varPtr) && (varPtr->refCount == 0)) {
            CleanupVar(varPtr, NULL);
        }
    }
}

static void
DupNsVarName(
    Tcl_Obj *srcPtr,
    Tcl_Obj *dupPtr)
{
    Namespace *nsPtr = srcPtr->internalRep.twoPtrValue.ptr1;
    register Var *varPtr = srcPtr->internalRep.twoPtrValue.ptr2;

    dupPtr->internalRep.twoPtrValue.ptr1 = nsPtr;
    dupPtr->internalRep.twoPtrValue.ptr2 = varPtr;
    if (TclIsVarInHash(varPtr)) {
        varPtr->refCount++;
    }
    dupPtr->typePtr = &tclNsVarNameType;
}
#endif

/*
 * parsedVarName -
 *
 * INTERNALREP DEFINITION:
 *   twoPtrValue.ptr1 = pointer to the array name Tcl_Obj (NULL if scalar)
 *   twoPtrValue.ptr2 = pointer to the element name string (owned by this
 *                      Tcl_Obj), or NULL if it is a scalar variable
 */

static void
FreeParsedVarName(
    Tcl_Obj *objPtr)
{
    register Tcl_Obj *arrayPtr = objPtr->internalRep.twoPtrValue.ptr1;
    register char *elem = objPtr->internalRep.twoPtrValue.ptr2;

    if (arrayPtr != NULL) {
        TclDecrRefCount(arrayPtr);
        ckfree(elem);
    }
}

static void
DupParsedVarName(
    Tcl_Obj *srcPtr,
    Tcl_Obj *dupPtr)
{
    register Tcl_Obj *arrayPtr = srcPtr->internalRep.twoPtrValue.ptr1;
    register char *elem = srcPtr->internalRep.twoPtrValue.ptr2;
    char *elemCopy;
    unsigned int elemLen;

    if (arrayPtr != NULL) {
        Tcl_IncrRefCount(arrayPtr);
        elemLen = strlen(elem);
        elemCopy = ckalloc(elemLen+1);
        memcpy(elemCopy, elem, elemLen);
        *(elemCopy + elemLen) = '\0';
        elem = elemCopy;
    }

    dupPtr->internalRep.twoPtrValue.ptr1 = arrayPtr;
    dupPtr->internalRep.twoPtrValue.ptr2 = elem;
    dupPtr->typePtr = &tclParsedVarNameType;
}

static void
UpdateParsedVarName(
    Tcl_Obj *objPtr)
{
    Tcl_Obj *arrayPtr = objPtr->internalRep.twoPtrValue.ptr1;
    char *part2 = objPtr->internalRep.twoPtrValue.ptr2;
    char *part1, *p;
    int len1, len2, totalLen;

    if (arrayPtr == NULL) {
        /*
         * This is a parsed scalar name: what is it doing here?
         */

        Tcl_Panic("scalar parsedVarName without a string rep");
    }

    part1 = TclGetStringFromObj(arrayPtr, &len1);
    len2 = strlen(part2);

    totalLen = len1 + len2 + 2;
    p = ckalloc((unsigned int) totalLen + 1);
    objPtr->bytes = p;
    objPtr->length = totalLen;

    memcpy(p, part1, (unsigned int) len1);
    p += len1;
    *p++ = '(';
    memcpy(p, part2, (unsigned int) len2);
    p += len2;
    *p++ = ')';
    *p = '\0';
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_FindNamespaceVar -- MOVED OVER from tclNamesp.c
 *
 *      Searches for a namespace variable, a variable not local to a
 *      procedure. The variable can be either a scalar or an array, but may
 *      not be an element of an array.
 *
 * Results:
 *      Returns a token for the variable if it is found. Otherwise, if it
 *      can't be found or there is an error, returns NULL and leaves an error
 *      message in the interpreter's result object if "flags" contains
 *      TCL_LEAVE_ERR_MSG.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

Tcl_Var
Tcl_FindNamespaceVar(
    Tcl_Interp *interp,         /* The interpreter in which to find the
                                 * variable. */
    const char *name,           /* Variable's name. If it starts with "::",
                                 * will be looked up in global namespace.
                                 * Else, looked up first in contextNsPtr
                                 * (current namespace if contextNsPtr is
                                 * NULL), then in global namespace. */
    Tcl_Namespace *contextNsPtr,/* Ignored if TCL_GLOBAL_ONLY flag set.
                                 * Otherwise, points to namespace in which to
                                 * resolve name. If NULL, look up name in the
                                 * current namespace. */
    int flags)                  /* An OR'd combination of: AVOID_RESOLVERS,
                                 * TCL_GLOBAL_ONLY (look up name only in
                                 * global namespace), TCL_NAMESPACE_ONLY (look
                                 * up only in contextNsPtr, or the current
                                 * namespace if contextNsPtr is NULL), and
                                 * TCL_LEAVE_ERR_MSG. If both TCL_GLOBAL_ONLY
                                 * and TCL_NAMESPACE_ONLY are given,
                                 * TCL_GLOBAL_ONLY is ignored. */
{
    Tcl_Obj *namePtr = Tcl_NewStringObj(name, -1);
    Tcl_Var var;

    Tcl_IncrRefCount(namePtr);
    var = ObjFindNamespaceVar(interp, namePtr, contextNsPtr, flags);
    Tcl_DecrRefCount(namePtr);
    return var;
}

static Tcl_Var
ObjFindNamespaceVar(
    Tcl_Interp *interp,         /* The interpreter in which to find the
                                 * variable. */
    Tcl_Obj *namePtr,           /* Variable's name. If it starts with "::",
                                 * will be looked up in global namespace.
                                 * Else, looked up first in contextNsPtr
                                 * (current namespace if contextNsPtr is
                                 * NULL), then in global namespace. */
    Tcl_Namespace *contextNsPtr,/* Ignored if TCL_GLOBAL_ONLY flag set.
                                 * Otherwise, points to namespace in which to
                                 * resolve name. If NULL, look up name in the
                                 * current namespace. */
    int flags)                  /* An OR'd combination of: AVOID_RESOLVERS,
                                 * TCL_GLOBAL_ONLY (look up name only in
                                 * global namespace), TCL_NAMESPACE_ONLY (look
                                 * up only in contextNsPtr, or the current
                                 * namespace if contextNsPtr is NULL), and
                                 * TCL_LEAVE_ERR_MSG. If both TCL_GLOBAL_ONLY
                                 * and TCL_NAMESPACE_ONLY are given,
                                 * TCL_GLOBAL_ONLY is ignored. */
{
    Interp *iPtr = (Interp *) interp;
    ResolverScheme *resPtr;
    Namespace *nsPtr[2], *cxtNsPtr;
    const char *simpleName;
    Var *varPtr;
    register int search;
    int result;
    Tcl_Var var;
    Tcl_Obj *simpleNamePtr;
    char *name = TclGetString(namePtr);

    /*
     * If this namespace has a variable resolver, then give it first crack at
     * the variable resolution. It may return a Tcl_Var value, it may signal
     * to continue onward, or it may signal an error.
     */

    if ((flags & TCL_GLOBAL_ONLY) != 0) {
        cxtNsPtr = (Namespace *) TclGetGlobalNamespace(interp);
    } else if (contextNsPtr != NULL) {
        cxtNsPtr = (Namespace *) contextNsPtr;
    } else {
        cxtNsPtr = (Namespace *) TclGetCurrentNamespace(interp);
    }

    if (!(flags & AVOID_RESOLVERS) &&
            (cxtNsPtr->varResProc != NULL || iPtr->resolverPtr != NULL)) {
        resPtr = iPtr->resolverPtr;

        if (cxtNsPtr->varResProc) {
            result = (*cxtNsPtr->varResProc)(interp, name,
                    (Tcl_Namespace *) cxtNsPtr, flags, &var);
        } else {
            result = TCL_CONTINUE;
        }

        while (result == TCL_CONTINUE && resPtr) {
            if (resPtr->varResProc) {
                result = (*resPtr->varResProc)(interp, name,
                        (Tcl_Namespace *) cxtNsPtr, flags, &var);
            }
            resPtr = resPtr->nextPtr;
        }

        if (result == TCL_OK) {
            return var;
        } else if (result != TCL_CONTINUE) {
            return (Tcl_Var) NULL;
        }
    }

    /*
     * Find the namespace(s) that contain the variable.
     */

    TclGetNamespaceForQualName(interp, name, (Namespace *) contextNsPtr,
            flags, &nsPtr[0], &nsPtr[1], &cxtNsPtr, &simpleName);

    /*
     * Look for the variable in the variable table of its namespace. Be sure
     * to check both possible search paths: from the specified namespace
     * context and from the global namespace.
     */

    varPtr = NULL;
    if (simpleName != name) {
        simpleNamePtr = Tcl_NewStringObj(simpleName, -1);
        Tcl_IncrRefCount(simpleNamePtr);
    } else {
        simpleNamePtr = namePtr;
    }

    for (search = 0;  (search < 2) && (varPtr == NULL);  search++) {
        if ((nsPtr[search] != NULL) && (simpleName != NULL)) {
            varPtr = VarHashFindVar(&nsPtr[search]->varTable, simpleNamePtr);
        }
    }
    if (simpleName != name) {
        Tcl_DecrRefCount(simpleNamePtr);
    }
    if ((varPtr == NULL) && (flags & TCL_LEAVE_ERR_MSG)) {
        Tcl_ResetResult(interp);
        Tcl_AppendResult(interp, "unknown variable \"", name, "\"", NULL);
        Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARIABLE", name, NULL);
    }
    return (Tcl_Var) varPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * InfoVarsCmd -- (moved over from tclCmdIL.c)
 *
 *      Called to implement the "info vars" command that returns the list of
 *      variables in the interpreter that match an optional pattern. The
 *      pattern, if any, consists of an optional sequence of namespace names
 *      separated by "::" qualifiers, which is followed by a glob-style
 *      pattern that restricts which variables are returned. Handles the
 *      following syntax:
 *
 *          info vars ?pattern?
 *
 * Results:
 *      Returns TCL_OK if successful and TCL_ERROR if there is an error.
 *
 * Side effects:
 *      Returns a result in the interpreter's result object. If there is an
 *      error, the result is an error message.
 *
 *----------------------------------------------------------------------
 */

int
TclInfoVarsCmd(
    ClientData dummy,           /* Not used. */
    Tcl_Interp *interp,         /* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    Interp *iPtr = (Interp *) interp;
    char *varName, *pattern;
    const char *simplePattern;
    Tcl_HashSearch search;
    Var *varPtr;
    Namespace *nsPtr;
    Namespace *globalNsPtr = (Namespace *) Tcl_GetGlobalNamespace(interp);
    Namespace *currNsPtr = (Namespace *) Tcl_GetCurrentNamespace(interp);
    Tcl_Obj *listPtr, *elemObjPtr;
    int specificNsInPattern = 0;/* Init. to avoid compiler warning. */
    Tcl_Obj *simplePatternPtr = NULL, *varNamePtr;

    /*
     * Get the pattern and find the "effective namespace" in which to list
     * variables. We only use this effective namespace if there's no active
     * Tcl procedure frame.
     */

    if (objc == 1) {
        simplePattern = NULL;
        nsPtr = currNsPtr;
        specificNsInPattern = 0;
    } else if (objc == 2) {
        /*
         * From the pattern, get the effective namespace and the simple
         * pattern (no namespace qualifiers or ::'s) at the end. If an error
         * was found while parsing the pattern, return it. Otherwise, if the
         * namespace wasn't found, just leave nsPtr NULL: we will return an
         * empty list since no variables there can be found.
         */

        Namespace *dummy1NsPtr, *dummy2NsPtr;

        pattern = TclGetString(objv[1]);
        TclGetNamespaceForQualName(interp, pattern, (Namespace *) NULL,
                /*flags*/ 0, &nsPtr, &dummy1NsPtr, &dummy2NsPtr,
                &simplePattern);

        if (nsPtr != NULL) {    /* We successfully found the pattern's ns. */
            specificNsInPattern = (strcmp(simplePattern, pattern) != 0);
            if (simplePattern == pattern) {
                simplePatternPtr = objv[1];
            } else {
                simplePatternPtr = Tcl_NewStringObj(simplePattern, -1);
            }
            Tcl_IncrRefCount(simplePatternPtr);
        }
    } else {
        Tcl_WrongNumArgs(interp, 1, objv, "?pattern?");
        return TCL_ERROR;
    }

    /*
     * If the namespace specified in the pattern wasn't found, just return.
     */

    if (nsPtr == NULL) {
        return TCL_OK;
    }

    listPtr = Tcl_NewListObj(0, NULL);

    if (!(iPtr->varFramePtr->isProcCallFrame & FRAME_IS_PROC)
            || specificNsInPattern) {
        /*
         * There is no frame pointer, the frame pointer was pushed only to
         * activate a namespace, or we are in a procedure call frame but a
         * specific namespace was specified. Create a list containing only the
         * variables in the effective namespace's variable table.
         */

        if (simplePattern && TclMatchIsTrivial(simplePattern)) {
            /*
             * If we can just do hash lookups, that simplifies things a lot.
             */

            varPtr = VarHashFindVar(&nsPtr->varTable, simplePatternPtr);
            if (varPtr) {
                if (!TclIsVarUndefined(varPtr)
                        || TclIsVarNamespaceVar(varPtr)) {
                    if (specificNsInPattern) {
                        elemObjPtr = Tcl_NewObj();
                        Tcl_GetVariableFullName(interp, (Tcl_Var) varPtr,
                                elemObjPtr);
                    } else {
                        elemObjPtr = VarHashGetKey(varPtr);
                    }
                    Tcl_ListObjAppendElement(interp, listPtr, elemObjPtr);
                }
            } else if ((nsPtr != globalNsPtr) && !specificNsInPattern) {
                varPtr = VarHashFindVar(&globalNsPtr->varTable,
                        simplePatternPtr);
                if (varPtr) {
                    if (!TclIsVarUndefined(varPtr)
                            || TclIsVarNamespaceVar(varPtr)) {
                        Tcl_ListObjAppendElement(interp, listPtr,
                                VarHashGetKey(varPtr));
                    }
                }
            }
        } else {
            /*
             * Have to scan the tables of variables.
             */

            varPtr = VarHashFirstVar(&nsPtr->varTable, &search);
            while (varPtr) {
                if (!TclIsVarUndefined(varPtr)
                        || TclIsVarNamespaceVar(varPtr)) {
                    varNamePtr = VarHashGetKey(varPtr);
                    varName = TclGetString(varNamePtr);
                    if ((simplePattern == NULL)
                            || Tcl_StringMatch(varName, simplePattern)) {
                        if (specificNsInPattern) {
                            elemObjPtr = Tcl_NewObj();
                            Tcl_GetVariableFullName(interp, (Tcl_Var) varPtr,
                                    elemObjPtr);
                        } else {
                            elemObjPtr = varNamePtr;
                        }
                        Tcl_ListObjAppendElement(interp, listPtr, elemObjPtr);
                    }
                }
                varPtr = VarHashNextVar(&search);
            }

            /*
             * If the effective namespace isn't the global :: namespace, and a
             * specific namespace wasn't requested in the pattern (i.e., the
             * pattern only specifies variable names), then add in all global
             * :: variables that match the simple pattern. Of course, add in
             * only those variables that aren't hidden by a variable in the
             * effective namespace.
             */

            if ((nsPtr != globalNsPtr) && !specificNsInPattern) {
                varPtr = VarHashFirstVar(&globalNsPtr->varTable,&search);
                while (varPtr) {
                    if (!TclIsVarUndefined(varPtr)
                            || TclIsVarNamespaceVar(varPtr)) {
                        varNamePtr = VarHashGetKey(varPtr);
                        varName = TclGetString(varNamePtr);
                        if ((simplePattern == NULL)
                                || Tcl_StringMatch(varName, simplePattern)) {
                            if (VarHashFindVar(&nsPtr->varTable,
                                    varNamePtr) == NULL) {
                                Tcl_ListObjAppendElement(interp, listPtr,
                                        varNamePtr);
                            }
                        }
                    }
                    varPtr = VarHashNextVar(&search);
                }
            }
        }
    } else if (((Interp *)interp)->varFramePtr->procPtr != NULL) {
        AppendLocals(interp, listPtr, simplePatternPtr, 1);
    }

    if (simplePatternPtr) {
        Tcl_DecrRefCount(simplePatternPtr);
    }
    Tcl_SetObjResult(interp, listPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * InfoGlobalsCmd -- (moved over from tclCmdIL.c)
 *
 *      Called to implement the "info globals" command that returns the list
 *      of global variables matching an optional pattern. Handles the
 *      following syntax:
 *
 *          info globals ?pattern?
 *
 * Results:
 *      Returns TCL_OK if successful and TCL_ERROR if there is an error.
 *
 * Side effects:
 *      Returns a result in the interpreter's result object. If there is an
 *      error, the result is an error message.
 *
 *----------------------------------------------------------------------
 */

int
TclInfoGlobalsCmd(
    ClientData dummy,           /* Not used. */
    Tcl_Interp *interp,         /* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    char *varName, *pattern;
    Namespace *globalNsPtr = (Namespace *) Tcl_GetGlobalNamespace(interp);
    Tcl_HashSearch search;
    Var *varPtr;
    Tcl_Obj *listPtr, *varNamePtr, *patternPtr;

    if (objc == 1) {
        pattern = NULL;
    } else if (objc == 2) {
        pattern = TclGetString(objv[1]);

        /*
         * Strip leading global-namespace qualifiers. [Bug 1057461]
         */

        if (pattern[0] == ':' && pattern[1] == ':') {
            while (*pattern == ':') {
                pattern++;
            }
        }
    } else {
        Tcl_WrongNumArgs(interp, 1, objv, "?pattern?");
        return TCL_ERROR;
    }

    /*
     * Scan through the global :: namespace's variable table and create a list
     * of all global variables that match the pattern.
     */

    listPtr = Tcl_NewListObj(0, NULL);
    if (pattern != NULL && TclMatchIsTrivial(pattern)) {
        if (pattern == TclGetString(objv[1])) {
            patternPtr = objv[1];
        } else {
            patternPtr = Tcl_NewStringObj(pattern, -1);
        }
        Tcl_IncrRefCount(patternPtr);

        varPtr = VarHashFindVar(&globalNsPtr->varTable, patternPtr);
        if (varPtr) {
            if (!TclIsVarUndefined(varPtr)) {
                Tcl_ListObjAppendElement(interp, listPtr,
                        VarHashGetKey(varPtr));
            }
        }
        Tcl_DecrRefCount(patternPtr);
    } else {
        for (varPtr = VarHashFirstVar(&globalNsPtr->varTable, &search);
                varPtr != NULL;
                varPtr = VarHashNextVar(&search)) {
            if (TclIsVarUndefined(varPtr)) {
                continue;
            }
            varNamePtr = VarHashGetKey(varPtr);
            varName = TclGetString(varNamePtr);
            if ((pattern == NULL) || Tcl_StringMatch(varName, pattern)) {
                Tcl_ListObjAppendElement(interp, listPtr, varNamePtr);
            }
        }
    }
    Tcl_SetObjResult(interp, listPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TclInfoLocalsCmd -- (moved over from tclCmdIl.c)
 *
 *      Called to implement the "info locals" command to return a list of
 *      local variables that match an optional pattern. Handles the following
 *      syntax:
 *
 *          info locals ?pattern?
 *
 * Results:
 *      Returns TCL_OK if successful and TCL_ERROR if there is an error.
 *
 * Side effects:
 *      Returns a result in the interpreter's result object. If there is an
 *      error, the result is an error message.
 *
 *----------------------------------------------------------------------
 */

int
TclInfoLocalsCmd(
    ClientData dummy,           /* Not used. */
    Tcl_Interp *interp,         /* Current interpreter. */
    int objc,                   /* Number of arguments. */
    Tcl_Obj *const objv[])      /* Argument objects. */
{
    Interp *iPtr = (Interp *) interp;
    Tcl_Obj *patternPtr;
    Tcl_Obj *listPtr;

    if (objc == 1) {
        patternPtr = NULL;
    } else if (objc == 2) {
        patternPtr = objv[1];
    } else {
        Tcl_WrongNumArgs(interp, 1, objv, "?pattern?");
        return TCL_ERROR;
    }

    if (!(iPtr->varFramePtr->isProcCallFrame & FRAME_IS_PROC )) {
        return TCL_OK;
    }

    /*
     * Return a list containing names of first the compiled locals (i.e. the
     * ones stored in the call frame), then the variables in the local hash
     * table (if one exists).
     */

    listPtr = Tcl_NewListObj(0, NULL);
    AppendLocals(interp, listPtr, patternPtr, 0);
    Tcl_SetObjResult(interp, listPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * AppendLocals --
 *
 *      Append the local variables for the current frame to the specified list
 *      object.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static void
AppendLocals(
    Tcl_Interp *interp,         /* Current interpreter. */
    Tcl_Obj *listPtr,           /* List object to append names to. */
    Tcl_Obj *patternPtr,        /* Pattern to match against. */
    int includeLinks)           /* 1 if upvars should be included, else 0. */
{
    Interp *iPtr = (Interp *) interp;
    Var *varPtr;
    int i, localVarCt;
    Tcl_Obj **varNamePtr;
    char *varName;
    TclVarHashTable *localVarTablePtr;
    Tcl_HashSearch search;
    const char *pattern = patternPtr? TclGetString(patternPtr) : NULL;
    Tcl_Obj *objNamePtr;

    localVarCt = iPtr->varFramePtr->numCompiledLocals;
    varPtr = iPtr->varFramePtr->compiledLocals;
    localVarTablePtr = iPtr->varFramePtr->varTablePtr;
    varNamePtr = &iPtr->varFramePtr->localCachePtr->varName0;

    for (i = 0; i < localVarCt; i++, varNamePtr++) {
        /*
         * Skip nameless (temporary) variables and undefined variables.
         */

        if (*varNamePtr && !TclIsVarUndefined(varPtr)
                && (includeLinks || !TclIsVarLink(varPtr))) {
            varName = TclGetString(*varNamePtr);
            if ((pattern == NULL) || Tcl_StringMatch(varName, pattern)) {
                Tcl_ListObjAppendElement(interp, listPtr, *varNamePtr);
            }
        }
        varPtr++;
    }

    /*
     * Do nothing if no local variables.
     */

    if (localVarTablePtr == NULL) {
        return;
    }

    /*
     * Check for the simple and fast case.
     */

    if ((pattern != NULL) && TclMatchIsTrivial(pattern)) {
        varPtr = VarHashFindVar(localVarTablePtr, patternPtr);
        if (varPtr != NULL) {
            if (!TclIsVarUndefined(varPtr)
                    && (includeLinks || !TclIsVarLink(varPtr))) {
                Tcl_ListObjAppendElement(interp, listPtr,
                        VarHashGetKey(varPtr));
            }
        }
        return;
    }

    /*
     * Scan over and process all local variables.
     */

    for (varPtr = VarHashFirstVar(localVarTablePtr, &search);
            varPtr != NULL;
            varPtr = VarHashNextVar(&search)) {
        if (!TclIsVarUndefined(varPtr)
                && (includeLinks || !TclIsVarLink(varPtr))) {
            objNamePtr = VarHashGetKey(varPtr);
            varName = TclGetString(objNamePtr);
            if ((pattern == NULL) || Tcl_StringMatch(varName, pattern)) {
                Tcl_ListObjAppendElement(interp, listPtr, objNamePtr);
            }
        }
    }
}

/*
 * Hash table implementation - first, just copy and adapt the obj key stuff
 */

void
TclInitVarHashTable(
    TclVarHashTable *tablePtr,
    Namespace *nsPtr)
{
    Tcl_InitCustomHashTable(&tablePtr->table,
            TCL_CUSTOM_TYPE_KEYS, &tclVarHashKeyType);
    tablePtr->nsPtr = nsPtr;
}

static Tcl_HashEntry *
AllocVarEntry(
    Tcl_HashTable *tablePtr,    /* Hash table. */
    void *keyPtr)               /* Key to store in the hash table entry. */
{
    Tcl_Obj *objPtr = (Tcl_Obj *) keyPtr;
    Tcl_HashEntry *hPtr;
    Var *varPtr;

    varPtr = (Var *) ckalloc(sizeof(VarInHash));
    varPtr->flags = VAR_IN_HASHTABLE;
    varPtr->value.objPtr = NULL;
    VarHashRefCount(varPtr) = 1;

    hPtr = &(((VarInHash *)varPtr)->entry);
    Tcl_SetHashValue(hPtr, varPtr);
    hPtr->key.objPtr = objPtr;
    Tcl_IncrRefCount(objPtr);

    return hPtr;
}

static void
FreeVarEntry(
    Tcl_HashEntry *hPtr)
{
    Var *varPtr = VarHashGetValue(hPtr);
    Tcl_Obj *objPtr = hPtr->key.objPtr;

    if (TclIsVarUndefined(varPtr) && !TclIsVarTraced(varPtr)
            && (VarHashRefCount(varPtr) == 1)) {
        ckfree((char *) varPtr);
    } else {
        VarHashInvalidateEntry(varPtr);
        TclSetVarUndefined(varPtr);
        VarHashRefCount(varPtr)--;
    }
    Tcl_DecrRefCount(objPtr);
}

static int
CompareVarKeys(
    void *keyPtr,               /* New key to compare. */
    Tcl_HashEntry *hPtr)        /* Existing key to compare. */
{
    Tcl_Obj *objPtr1 = (Tcl_Obj *) keyPtr;
    Tcl_Obj *objPtr2 = hPtr->key.objPtr;
    register const char *p1, *p2;
    register int l1, l2;

    /*
     * If the object pointers are the same then they match.
     */

    if (objPtr1 == objPtr2) {
        return 1;
    }

    /*
     * Don't use Tcl_GetStringFromObj as it would prevent l1 and l2 being in a
     * register.
     */

    p1 = TclGetString(objPtr1);
    l1 = objPtr1->length;
    p2 = TclGetString(objPtr2);
    l2 = objPtr2->length;

    /*
     * Only compare if the string representations are of the same length.
     */

    if (l1 == l2) {
        for (;; p1++, p2++, l1--) {
            if (*p1 != *p2) {
                break;
            }
            if (l1 == 0) {
                return 1;
            }
        }
    }

    return 0;
}

static unsigned int
HashVarKey(
    Tcl_HashTable *tablePtr,    /* Hash table. */
    void *keyPtr)               /* Key from which to compute hash value. */
{
    Tcl_Obj *objPtr = (Tcl_Obj *) keyPtr;
    const char *string = TclGetString(objPtr);
    int length = objPtr->length;
    unsigned int result = 0;
    int i;

    /*
     * I tried a zillion different hash functions and asked many other people
     * for advice. Many people had their own favorite functions, all
     * different, but no-one had much idea why they were good ones. I chose
     * the one below (multiply by 9 and add new character) because of the
     * following reasons:
     *
     * 1. Multiplying by 10 is perfect for keys that are decimal strings, and
     *    multiplying by 9 is just about as good.
     * 2. Times-9 is (shift-left-3) plus (old). This means that each
     *    character's bits hang around in the low-order bits of the hash value
     *    for ever, plus they spread fairly rapidly up to the high-order bits
     *    to fill out the hash value. This seems works well both for decimal
     *    and non-decimal strings.
     */

    for (i=0 ; i<length ; i++) {
        result += (result << 3) + string[i];
    }
    return result;
}

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