C/C++ Users Group Library 1996 July/C-C++ Users Group Library July 1996.iso/vol_400/405_01/flexpp/parse.y

Text File | 1993-04-15 | 14.6 KB | 725 lines

/* 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: /usr/fsys/odin/a/vern/flex/RCS/parse.y,v 2.7 90/06/27 23:48:31 vern 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
            {
                $$ = $1;

            if ( trlcontxt )
                {
                if ( varlength && headcnt == 0 )
                /* both head and trail are variable-length */
                variable_trail_rule = true;
                else
                trailcnt = rulelen;
                }
                }
        ;


re              :  re '|' series
                        {
            varlength = true;
            $$ = mkor( $1, $3 );
            }

        |  series
            { $$ = $1; }
        ;


re2        :  re '/'
            {
            /* this rule is written separately so
             * the reduction will occur before the trailing
             * series is parsed
             */

            if ( trlcontxt )
                synerr( "trailing context used twice" );
            else
                trlcontxt = true;

            if ( varlength )
                /* we hope the trailing context is fixed-length */
                varlength = false;
            else
                headcnt = rulelen;

            rulelen = 0;

            current_state_type = STATE_TRAILING_CONTEXT;
            $$ = $1;
            }
        ;

series          :  series singleton
                        {
            /* this is where concatenation of adjacent patterns
             * gets done
             */
            $$ = link_machines( $1, $2 );
            }

        |  singleton
            { $$ = $1; }
        ;

singleton       :  singleton '*'
                        {
            varlength = true;

            $$ = mkclos( $1 );
            }

        |  singleton '+'
            {
            varlength = true;

            $$ = mkposcl( $1 );
            }

        |  singleton '?'
            {
            varlength = true;

            $$ = mkopt( $1 );
            }

        |  singleton '{' NUMBER ',' NUMBER '}'
            {
            varlength = true;

            if ( $3 > $5 || $3 < 0 )
                {
                synerr( "bad iteration values" );
                $$ = $1;
                }
            else
                {
                if ( $3 == 0 )
                 {
                 if ( $5 <= 0 )
                     {
                     synerr( "bad iteration values" );
                     $$ = $1;
                     }
                 else
                     $$ = mkopt( mkrep( $1, 1, $5 ) );
                 }
                else
                $$ = mkrep( $1, $3, $5 );
                }
            }

        |  singleton '{' NUMBER ',' '}'
            {
            varlength = true;

            if ( $3 <= 0 )
                {
                synerr( "iteration value must be positive" );
                $$ = $1;
                }

            else
                $$ = mkrep( $1, $3, INFINITY );
            }

        |  singleton '{' NUMBER '}'
            {
            /* the singleton could be something like "(foo)",
             * in which case we have no idea what its length
             * is, so we punt here.
             */
            varlength = true;

            if ( $3 <= 0 )
                {
                synerr( "iteration value must be positive" );
                $$ = $1;
                }

            else
                $$ = link_machines( $1, copysingl( $1, $3 - 1 ) );
            }

        |  '.'
            {
            if ( ! madeany )
                {
                /* create the '.' character class */
                anyccl = cclinit();
                ccladd( anyccl, '\n' );
                cclnegate( anyccl );

                if ( useecs )
                mkeccl( ccltbl + cclmap[anyccl],
                    ccllen[anyccl], nextecm,
                    ecgroup, csize, csize );

                madeany = true;
                }

            ++rulelen;

            $$ = mkstate( -anyccl );
            }

        |  fullccl
            {
            if ( ! cclsorted )
                /* sort characters for fast searching.  We use a
                 * shell sort since this list could be large.
                 */
                cshell( ccltbl + cclmap[$1], ccllen[$1], true );

            if ( useecs )
                mkeccl( ccltbl + cclmap[$1], ccllen[$1],
                    nextecm, ecgroup, csize, csize );

            ++rulelen;

            $$ = mkstate( -$1 );
            }

        |  PREVCCL
            {
            ++rulelen;

            $$ = mkstate( -$1 );
            }

        |  '"' string '"'
            { $$ = $2; }

        |  '(' re ')'
            { $$ = $2; }

        |  CHAR
            {
            ++rulelen;

            if ( caseins && $1 >= 'A' && $1 <= 'Z' )
                $1 = clower( $1 );

            $$ = mkstate( $1 );
            }
        ;

fullccl        :  '[' ccl ']'
            { $$ = $2; }

        |  '[' '^' ccl ']'
            {
            /* *Sigh* - to be compatible Unix lex, negated ccls
             * match newlines
             */
#ifdef NOTDEF
            ccladd( $3, '\n' ); /* negated ccls don't match '\n' */
            cclsorted = false; /* because we added the newline */
#endif
            cclnegate( $3 );
            $$ = $3;
            }
        ;

ccl             :  ccl CHAR '-' CHAR
                        {
            if ( $2 > $4 )
                synerr( "negative range in character class" );

            else
                {
                if ( caseins )
                {
                if ( $2 >= 'A' && $2 <= 'Z' )
                    $2 = clower( $2 );
                if ( $4 >= 'A' && $4 <= 'Z' )
                    $4 = clower( $4 );
                }

                for ( i = $2; i <= $4; ++i )
                    ccladd( $1, i );

                /* keep track if this ccl is staying in alphabetical
                 * order
                 */
                cclsorted = cclsorted && ($2 > lastchar);
                lastchar = $4;
                }

            $$ = $1;
            }

        |  ccl CHAR
                {
            if ( caseins )
                if ( $2 >= 'A' && $2 <= 'Z' )
                $2 = clower( $2 );

            ccladd( $1, $2 );
            cclsorted = cclsorted && ($2 > lastchar);
            lastchar = $2;
            $$ = $1;
            }

        |
            {
            cclsorted = true;
            lastchar = 0;
            $$ = cclinit();
            }
        ;

string        :  string CHAR
                        {
            if ( caseins )
                if ( $2 >= 'A' && $2 <= 'Z' )
                $2 = clower( $2 );

            ++rulelen;

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

        |
            { $$ = mkstate( SYM_EPSILON ); }
        ;

%%


/* build_eof_action - build the "<<EOF>>" action for the active start
 *                    conditions
 */

void build_eof_action()

    {
    register int i;

    for ( i = 1; i <= actvp; ++i )
    {
    if ( sceof[actvsc[i]] )
        format_pinpoint_message(
        "multiple <<EOF>> rules for start condition %s",
            scname[actvsc[i]] );

    else
        {
        sceof[actvsc[i]] = true;
        fprintf( temp_action_file, "case YY_STATE_EOF(%s):\n",
             scname[actvsc[i]] );
        }
    }

    line_directive_out( temp_action_file );
    }


/* synerr - report a syntax error */

void synerr( str )
char str[];

    {
    syntaxerror = true;
    pinpoint_message( str );
    }


/* format_pinpoint_message - write out a message formatted with one string,
 *                 pinpointing its location
 */

void format_pinpoint_message( msg, arg )
char msg[], arg[];

    {
    char errmsg[MAXLINE];

    (void) sprintf( errmsg, msg, arg );
    pinpoint_message( errmsg );
    }


/* pinpoint_message - write out a message, pinpointing its location */

void pinpoint_message( str )
char str[];

    {
    fprintf( stderr, "\"%s\", line %d: %s\n", infilename, linenum, str );
    }


/* yyerror - eat up an error message from the parser;
 *         currently, messages are ignore
 */

void yyerror( msg )
char msg[];

    {
    }