parse.y

C++版 词法分析、语法分析器

/* parse.y - parser for flex input */

%token CHAR NUMBER SECTEND SCDECL XSCDECL WHITESPACE NAME PREVCCL EOF_OP

%{
/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Vern Paxson.
 * 
 * The United States Government has rights in this work pursuant
 * to contract no. DE-AC03-76SF00098 between the United States
 * Department of Energy and the University of California.
 *
 * Redistribution and use in source and binary forms are permitted provided
 * that: (1) source distributions retain this entire copyright notice and
 * comment, and (2) distributions including binaries display the following
 * acknowledgement:  ``This product includes software developed by the
 * University of California, Berkeley and its contributors'' in the
 * documentation or other materials provided with the distribution and in
 * all advertising materials mentioning features or use of this software.
 * Neither the name of the University nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char rcsid[] =
    "@(#) $Header: c:\\program\040files\\development\\cvs\040repository/flex++/parse.y,v 1.1.1.1 2002/04/13 06:01:33 Bear Exp $ (LBL)";
#endif

#include "flexdef.h"
void yyerror();
void build_eof_action();

int pat, scnum, eps, headcnt, trailcnt, anyccl, lastchar, i, actvp, rulelen;
int trlcontxt, xcluflg, cclsorted, varlength, variable_trail_rule;
Char clower();

static int madeany = false;  /* whether we've made the '.' character class */
int previous_continued_action;	/* whether the previous rule's action was '|' */

%}

%%
goal            :  initlex sect1 sect1end sect2 initforrule
			{ /* add default rule */
			int def_rule;

			pat = cclinit();
			cclnegate( pat );

			def_rule = mkstate( -pat );

			finish_rule( def_rule, false, 0, 0 );

			for ( i = 1; i <= lastsc; ++i )
			    scset[i] = mkbranch( scset[i], def_rule );

			if ( spprdflt )
			    fputs( "YY_FATAL_ERROR( \"flex scanner jammed\" )",
				   temp_action_file );
			else
			    fputs( "ECHO", temp_action_file );

			fputs( ";\n\tYY_BREAK\n", temp_action_file );
			}
		;

initlex         :
			{
			/* initialize for processing rules */

			/* create default DFA start condition */
			scinstal( "INITIAL", false );
			}
		;

sect1		:  sect1 startconddecl WHITESPACE namelist1 '\n'
		|
		|  error '\n'
			{ synerr( "unknown error processing section 1" ); }
		;

sect1end	:  SECTEND
		;

startconddecl   :  SCDECL
			{
			/* these productions are separate from the s1object
			 * rule because the semantics must be done before
			 * we parse the remainder of an s1object
			 */

			xcluflg = false;
			}

		|  XSCDECL
			{ xcluflg = true; }
		;

namelist1	:  namelist1 WHITESPACE NAME
			{ scinstal( nmstr, xcluflg ); }

		|  NAME
			{ scinstal( nmstr, xcluflg ); }

		|  error
                        { synerr( "bad start condition list" ); }
		;

sect2           :  sect2 initforrule flexrule '\n'
		|
		;

initforrule     :
			{
			/* initialize for a parse of one rule */
			trlcontxt = variable_trail_rule = varlength = false;
			trailcnt = headcnt = rulelen = 0;
			current_state_type = STATE_NORMAL;
			previous_continued_action = continued_action;
			new_rule();
			}
		;

flexrule        :  scon '^' rule
                        {
			pat = $3;
			finish_rule( pat, variable_trail_rule,
				     headcnt, trailcnt );

			for ( i = 1; i <= actvp; ++i )
			    scbol[actvsc[i]] =
				mkbranch( scbol[actvsc[i]], pat );

			if ( ! bol_needed )
			    {
			    bol_needed = true;

			    if ( performance_report )
				pinpoint_message( 
			    "'^' operator results in sub-optimal performance" );
			    }
			}

		|  scon rule
                        {
			pat = $2;
			finish_rule( pat, variable_trail_rule,
				     headcnt, trailcnt );

			for ( i = 1; i <= actvp; ++i )
			    scset[actvsc[i]] =
				mkbranch( scset[actvsc[i]], pat );
			}

                |  '^' rule
			{
			pat = $2;
			finish_rule( pat, variable_trail_rule,
				     headcnt, trailcnt );

			/* add to all non-exclusive start conditions,
			 * including the default (0) start condition
			 */

			for ( i = 1; i <= lastsc; ++i )
			    if ( ! scxclu[i] )
				scbol[i] = mkbranch( scbol[i], pat );

			if ( ! bol_needed )
			    {
			    bol_needed = true;

			    if ( performance_report )
				pinpoint_message(
			    "'^' operator results in sub-optimal performance" );
			    }
			}

                |  rule
			{
			pat = $1;
			finish_rule( pat, variable_trail_rule,
				     headcnt, trailcnt );

			for ( i = 1; i <= lastsc; ++i )
			    if ( ! scxclu[i] )
				scset[i] = mkbranch( scset[i], pat );
			}

                |  scon EOF_OP
			{ build_eof_action(); }

                |  EOF_OP
			{
			/* this EOF applies to all start conditions
			 * which don't already have EOF actions
			 */
			actvp = 0;

			for ( i = 1; i <= lastsc; ++i )
			    if ( ! sceof[i] )
				actvsc[++actvp] = i;

			if ( actvp == 0 )
			    pinpoint_message(
		"warning - all start conditions already have <<EOF>> rules" );

			else
			    build_eof_action();
			}

                |  error
			{ synerr( "unrecognized rule" ); }
		;

scon            :  '<' namelist2 '>'
		;

namelist2       :  namelist2 ',' NAME
                        {
			if ( (scnum = sclookup( nmstr )) == 0 )
			    format_pinpoint_message(
				"undeclared start condition %s", nmstr );

			else
			    actvsc[++actvp] = scnum;
			}

		|  NAME
			{
			if ( (scnum = sclookup( nmstr )) == 0 )
			    format_pinpoint_message(
				"undeclared start condition %s", nmstr );
			else
			    actvsc[actvp = 1] = scnum;
			}

		|  error
			{ synerr( "bad start condition list" ); }
		;

rule            :  re2 re
			{
			if ( transchar[lastst[$2]] != SYM_EPSILON )
			    /* provide final transition \now/ so it
			     * will be marked as a trailing context
			     * state
			     */
			    $2 = link_machines( $2, mkstate( SYM_EPSILON ) );

			mark_beginning_as_normal( $2 );
			current_state_type = STATE_NORMAL;

			if ( previous_continued_action )
			    {
			    /* we need to treat this as variable trailing
			     * context so that the backup does not happen
			     * in the action but before the action switch
			     * statement.  If the backup happens in the
			     * action, then the rules "falling into" this
			     * one's action will *also* do the backup,
			     * erroneously.
			     */
			    if ( ! varlength || headcnt != 0 )
				{
				fprintf( stderr,
    "%s: warning - trailing context rule at line %d made variable because\n",
					 program_name, linenum );
				fprintf( stderr,
					 "      of preceding '|' action\n" );
				}

			    /* mark as variable */
			    varlength = true;
			    headcnt = 0;
			    }

			if ( varlength && headcnt == 0 )
			    { /* variable trailing context rule */
			    /* mark the first part of the rule as the accepting
			     * "head" part of a trailing context rule
			     */
			    /* by the way, we didn't do this at the beginning
			     * of this production because back then
			     * current_state_type was set up for a trail
			     * rule, and add_accept() can create a new
			     * state ...
			     */
			    add_accept( $1, num_rules | YY_TRAILING_HEAD_MASK );
			    variable_trail_rule = true;
			    }
			
			else
			    trailcnt = rulelen;

			$$ = link_machines( $1, $2 );
			}

		|  re2 re '$'
			{ synerr( "trailing context used twice" ); }

		|  re '$'
                        {
			if ( trlcontxt )
			    {
			    synerr( "trailing context used twice" );
			    $$ = mkstate( SYM_EPSILON );
			    }

			else if ( previous_continued_action )
			    {
			    /* see the comment in the rule for "re2 re"
			     * above
			     */
			    if ( ! varlength || headcnt != 0 )
				{
				fprintf( stderr,
    "%s: warning - trailing context rule at line %d made variable because\n",
					 program_name, linenum );
				fprintf( stderr,
					 "      of preceding '|' action\n" );
				}

			    /* mark as variable */
			    varlength = true;
			    headcnt = 0;
			    }

 			if ( varlength && headcnt == 0 )
 			    {
 			    /* again, see the comment in the rule for "re2 re"
 			     * above
 			     */
 			    add_accept( $1, num_rules | YY_TRAILING_HEAD_MASK );
 			    variable_trail_rule = true;
 			    }

 			else
 			    {
 			    if ( ! varlength )
 				headcnt = rulelen;

 			    ++rulelen;
 			    trailcnt = 1;
 			    }

			trlcontxt = true;

			eps = mkstate( SYM_EPSILON );
			$$ = link_machines( $1,
				 link_machines( eps, mkstate( '\n' ) ) );
			}

		|  re