parse.c

C++的一个好库。。。现在很流行

/*
 * 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);
}