source: downloads/boost_1_33_1/tools/build/jam_src/parse.c @ 12

/*
 * Copyright 1993, 2000 Christopher Seiwald.
 *
 * This file is part of Jam - see jam.c for Copyright information.
 */

/*  This file is ALSO:
 *  Copyright 2001-2004 David Abrahams.
 *  Distributed under the Boost Software License, Version 1.0.
 *  (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
 */

# include "jam.h"
# include "lists.h"
# include "parse.h"
# include "scan.h"
# include "newstr.h"
# include "modules.h"
# include "frames.h"

/*
 * parse.c - make and destroy parse trees as driven by the parser
 *
 * 09/07/00 (seiwald) - ref count on PARSE to avoid freeing when used,
 *              as per Matt Armstrong.
 * 09/11/00 (seiwald) - structure reworked to reflect that (*func)()
 *              returns a LIST *.
 */

static PARSE *yypsave;

void
parse_file( char *f, FRAME* frame )
{
        /* Suspend scan of current file */
        /* and push this new file in the stream */

        yyfparse(f);

        /* Now parse each block of rules and execute it. */
        /* Execute it outside of the parser so that recursive */
        /* calls to yyrun() work (no recursive yyparse's). */

        for(;;)
        {
            PARSE *p;

            /* Filled by yyparse() calling parse_save() */

            yypsave = 0;

            /* If parse error or empty parse, outta here */

            if( yyparse() || !( p = yypsave ) )
                break;

            /* Run the parse tree. */

            parse_evaluate( p, frame );
            parse_free( p );
        }
}

void
parse_save( PARSE *p )
{
        yypsave = p;
}

PARSE *
parse_make( 
        LIST    *(*func)( PARSE *p, FRAME *args ),
        PARSE   *left,
        PARSE   *right,
        PARSE   *third,
        char    *string,
        char    *string1,
        int     num )
{
        PARSE   *p = (PARSE *)malloc( sizeof( PARSE ) );

        p->func = func;
        p->left = left;
        p->right = right;
        p->third = third;
        p->string = string;
        p->string1 = string1;
        p->num = num;
        p->refs = 1;
        p->rulename = 0;
        
        if ( left )
        {
            p->file = left->file;
            p->line = left->line;
        }
        else
        {
            yyinput_stream( &p->file, &p->line );
        }

        return p;
}

void
parse_refer( PARSE *p )
{
        ++p->refs;
}

void
parse_free( PARSE *p )
{
        if( --p->refs )
            return;

        if( p->string )
            freestr( p->string );
        if( p->string1 )
            freestr( p->string1 );
        if( p->left )
            parse_free( p->left );
        if( p->right )
            parse_free( p->right );
        if( p->third )
            parse_free( p->third );
        if ( p->rulename )
            freestr( p->rulename );
        
        free( (char *)p );
}

LIST* parse_evaluate( PARSE *p, FRAME* frame )
{
    frame->procedure = p;
    return (*p->func)(p, frame);
}