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712 lines
17 KiB
C
712 lines
17 KiB
C
/* nfa - NFA construction routines */
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/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Vern Paxson.
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*
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* The United States Government has rights in this work pursuant
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* to contract no. DE-AC03-76SF00098 between the United States
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* Department of Energy and the University of California.
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*
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* Redistribution and use in source and binary forms are permitted provided
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* that: (1) source distributions retain this entire copyright notice and
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* comment, and (2) distributions including binaries display the following
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* acknowledgement: ``This product includes software developed by the
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* University of California, Berkeley and its contributors'' in the
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* documentation or other materials provided with the distribution and in
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* all advertising materials mentioning features or use of this software.
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* Neither the name of the University nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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/* $Header: /home/daffy/u0/vern/flex/RCS/nfa.c,v 2.17 95/03/04 16:11:42 vern Exp $ */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "flexdef.h"
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/* declare functions that have forward references */
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int dupmachine PROTO((int));
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void mkxtion PROTO((int, int));
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/* add_accept - add an accepting state to a machine
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*
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* accepting_number becomes mach's accepting number.
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*/
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void add_accept( mach, accepting_number )
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int mach, accepting_number;
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{
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/* Hang the accepting number off an epsilon state. if it is associated
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* with a state that has a non-epsilon out-transition, then the state
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* will accept BEFORE it makes that transition, i.e., one character
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* too soon.
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*/
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if ( transchar[finalst[mach]] == SYM_EPSILON )
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accptnum[finalst[mach]] = accepting_number;
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else
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{
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int astate = mkstate( SYM_EPSILON );
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accptnum[astate] = accepting_number;
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(void) link_machines( mach, astate );
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}
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}
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/* copysingl - make a given number of copies of a singleton machine
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*
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* synopsis
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*
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* newsng = copysingl( singl, num );
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*
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* newsng - a new singleton composed of num copies of singl
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* singl - a singleton machine
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* num - the number of copies of singl to be present in newsng
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*/
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int copysingl( singl, num )
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int singl, num;
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{
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int copy, i;
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copy = mkstate( SYM_EPSILON );
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for ( i = 1; i <= num; ++i )
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copy = link_machines( copy, dupmachine( singl ) );
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return copy;
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}
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/* dumpnfa - debugging routine to write out an nfa */
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void dumpnfa( state1 )
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int state1;
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{
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int sym, tsp1, tsp2, anum, ns;
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fprintf( stderr,
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_( "\n\n********** beginning dump of nfa with start state %d\n" ),
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state1 );
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/* We probably should loop starting at firstst[state1] and going to
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* lastst[state1], but they're not maintained properly when we "or"
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* all of the rules together. So we use our knowledge that the machine
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* starts at state 1 and ends at lastnfa.
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*/
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/* for ( ns = firstst[state1]; ns <= lastst[state1]; ++ns ) */
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for ( ns = 1; ns <= lastnfa; ++ns )
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{
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fprintf( stderr, _( "state # %4d\t" ), ns );
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sym = transchar[ns];
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tsp1 = trans1[ns];
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tsp2 = trans2[ns];
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anum = accptnum[ns];
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fprintf( stderr, "%3d: %4d, %4d", sym, tsp1, tsp2 );
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if ( anum != NIL )
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fprintf( stderr, " [%d]", anum );
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fprintf( stderr, "\n" );
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}
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fprintf( stderr, _( "********** end of dump\n" ) );
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}
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/* dupmachine - make a duplicate of a given machine
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*
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* synopsis
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*
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* copy = dupmachine( mach );
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*
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* copy - holds duplicate of mach
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* mach - machine to be duplicated
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*
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* note that the copy of mach is NOT an exact duplicate; rather, all the
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* transition states values are adjusted so that the copy is self-contained,
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* as the original should have been.
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*
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* also note that the original MUST be contiguous, with its low and high
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* states accessible by the arrays firstst and lastst
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*/
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int dupmachine( mach )
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int mach;
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{
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int i, init, state_offset;
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int state = 0;
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int last = lastst[mach];
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for ( i = firstst[mach]; i <= last; ++i )
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{
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state = mkstate( transchar[i] );
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if ( trans1[i] != NO_TRANSITION )
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{
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mkxtion( finalst[state], trans1[i] + state - i );
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if ( transchar[i] == SYM_EPSILON &&
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trans2[i] != NO_TRANSITION )
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mkxtion( finalst[state],
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trans2[i] + state - i );
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}
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accptnum[state] = accptnum[i];
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}
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if ( state == 0 )
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flexfatal( _( "empty machine in dupmachine()" ) );
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state_offset = state - i + 1;
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init = mach + state_offset;
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firstst[init] = firstst[mach] + state_offset;
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finalst[init] = finalst[mach] + state_offset;
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lastst[init] = lastst[mach] + state_offset;
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return init;
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}
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/* finish_rule - finish up the processing for a rule
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*
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* An accepting number is added to the given machine. If variable_trail_rule
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* is true then the rule has trailing context and both the head and trail
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* are variable size. Otherwise if headcnt or trailcnt is non-zero then
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* the machine recognizes a pattern with trailing context and headcnt is
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* the number of characters in the matched part of the pattern, or zero
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* if the matched part has variable length. trailcnt is the number of
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* trailing context characters in the pattern, or zero if the trailing
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* context has variable length.
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*/
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void finish_rule( mach, variable_trail_rule, headcnt, trailcnt )
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int mach, variable_trail_rule, headcnt, trailcnt;
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{
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char action_text[MAXLINE];
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add_accept( mach, num_rules );
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/* We did this in new_rule(), but it often gets the wrong
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* number because we do it before we start parsing the current rule.
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*/
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rule_linenum[num_rules] = linenum;
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/* If this is a continued action, then the line-number has already
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* been updated, giving us the wrong number.
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*/
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if ( continued_action )
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--rule_linenum[num_rules];
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sprintf( action_text, "case %d:\n", num_rules );
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add_action( action_text );
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if ( variable_trail_rule )
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{
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rule_type[num_rules] = RULE_VARIABLE;
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if ( performance_report > 0 )
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fprintf( stderr,
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_( "Variable trailing context rule at line %d\n" ),
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rule_linenum[num_rules] );
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variable_trailing_context_rules = true;
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}
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else
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{
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rule_type[num_rules] = RULE_NORMAL;
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if ( headcnt > 0 || trailcnt > 0 )
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{
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/* Do trailing context magic to not match the trailing
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* characters.
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*/
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char *scanner_cp = "yy_c_buf_p = yy_cp";
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char *scanner_bp = "yy_bp";
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add_action(
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"*yy_cp = yy_hold_char; /* undo effects of setting up yytext */\n" );
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if ( headcnt > 0 )
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{
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sprintf( action_text, "%s = %s + %d;\n",
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scanner_cp, scanner_bp, headcnt );
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add_action( action_text );
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}
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else
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{
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sprintf( action_text, "%s -= %d;\n",
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scanner_cp, trailcnt );
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add_action( action_text );
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}
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add_action(
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"YY_DO_BEFORE_ACTION; /* set up yytext again */\n" );
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}
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}
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/* Okay, in the action code at this point yytext and yyleng have
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* their proper final values for this rule, so here's the point
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* to do any user action. But don't do it for continued actions,
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* as that'll result in multiple YY_RULE_SETUP's.
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*/
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if ( ! continued_action )
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add_action( "YY_RULE_SETUP\n" );
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line_directive_out( (FILE *) 0, 1 );
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}
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/* link_machines - connect two machines together
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*
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* synopsis
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*
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* new = link_machines( first, last );
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*
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* new - a machine constructed by connecting first to last
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* first - the machine whose successor is to be last
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* last - the machine whose predecessor is to be first
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*
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* note: this routine concatenates the machine first with the machine
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* last to produce a machine new which will pattern-match first first
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* and then last, and will fail if either of the sub-patterns fails.
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* FIRST is set to new by the operation. last is unmolested.
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*/
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int link_machines( first, last )
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int first, last;
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{
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if ( first == NIL )
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return last;
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else if ( last == NIL )
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return first;
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else
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{
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mkxtion( finalst[first], last );
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finalst[first] = finalst[last];
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lastst[first] = MAX( lastst[first], lastst[last] );
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firstst[first] = MIN( firstst[first], firstst[last] );
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return first;
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}
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}
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/* mark_beginning_as_normal - mark each "beginning" state in a machine
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* as being a "normal" (i.e., not trailing context-
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* associated) states
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*
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* The "beginning" states are the epsilon closure of the first state
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*/
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void mark_beginning_as_normal( mach )
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register int mach;
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{
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switch ( state_type[mach] )
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{
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case STATE_NORMAL:
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/* Oh, we've already visited here. */
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return;
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case STATE_TRAILING_CONTEXT:
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state_type[mach] = STATE_NORMAL;
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if ( transchar[mach] == SYM_EPSILON )
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{
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if ( trans1[mach] != NO_TRANSITION )
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mark_beginning_as_normal(
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trans1[mach] );
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if ( trans2[mach] != NO_TRANSITION )
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mark_beginning_as_normal(
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trans2[mach] );
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}
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break;
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default:
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flexerror(
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_( "bad state type in mark_beginning_as_normal()" ) );
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break;
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}
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}
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/* mkbranch - make a machine that branches to two machines
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*
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* synopsis
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*
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* branch = mkbranch( first, second );
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*
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* branch - a machine which matches either first's pattern or second's
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* first, second - machines whose patterns are to be or'ed (the | operator)
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*
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* Note that first and second are NEITHER destroyed by the operation. Also,
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* the resulting machine CANNOT be used with any other "mk" operation except
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* more mkbranch's. Compare with mkor()
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*/
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int mkbranch( first, second )
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int first, second;
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{
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int eps;
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if ( first == NO_TRANSITION )
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return second;
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else if ( second == NO_TRANSITION )
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return first;
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eps = mkstate( SYM_EPSILON );
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mkxtion( eps, first );
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mkxtion( eps, second );
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return eps;
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}
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/* mkclos - convert a machine into a closure
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*
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* synopsis
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* new = mkclos( state );
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*
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* new - a new state which matches the closure of "state"
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*/
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int mkclos( state )
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int state;
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{
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return mkopt( mkposcl( state ) );
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}
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/* mkopt - make a machine optional
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*
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* synopsis
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*
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* new = mkopt( mach );
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*
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* new - a machine which optionally matches whatever mach matched
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* mach - the machine to make optional
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*
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* notes:
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* 1. mach must be the last machine created
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* 2. mach is destroyed by the call
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*/
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int mkopt( mach )
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int mach;
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{
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int eps;
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if ( ! SUPER_FREE_EPSILON(finalst[mach]) )
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{
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eps = mkstate( SYM_EPSILON );
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mach = link_machines( mach, eps );
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}
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/* Can't skimp on the following if FREE_EPSILON(mach) is true because
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* some state interior to "mach" might point back to the beginning
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* for a closure.
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*/
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eps = mkstate( SYM_EPSILON );
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mach = link_machines( eps, mach );
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mkxtion( mach, finalst[mach] );
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return mach;
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}
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/* mkor - make a machine that matches either one of two machines
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*
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* synopsis
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*
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* new = mkor( first, second );
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*
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* new - a machine which matches either first's pattern or second's
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* first, second - machines whose patterns are to be or'ed (the | operator)
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*
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* note that first and second are both destroyed by the operation
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* the code is rather convoluted because an attempt is made to minimize
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* the number of epsilon states needed
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*/
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int mkor( first, second )
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int first, second;
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{
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int eps, orend;
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if ( first == NIL )
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return second;
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else if ( second == NIL )
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return first;
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else
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{
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/* See comment in mkopt() about why we can't use the first
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* state of "first" or "second" if they satisfy "FREE_EPSILON".
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*/
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eps = mkstate( SYM_EPSILON );
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first = link_machines( eps, first );
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mkxtion( first, second );
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if ( SUPER_FREE_EPSILON(finalst[first]) &&
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accptnum[finalst[first]] == NIL )
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{
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orend = finalst[first];
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mkxtion( finalst[second], orend );
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}
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else if ( SUPER_FREE_EPSILON(finalst[second]) &&
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accptnum[finalst[second]] == NIL )
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{
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orend = finalst[second];
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mkxtion( finalst[first], orend );
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}
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else
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{
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eps = mkstate( SYM_EPSILON );
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first = link_machines( first, eps );
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orend = finalst[first];
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mkxtion( finalst[second], orend );
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}
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}
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finalst[first] = orend;
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return first;
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}
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/* mkposcl - convert a machine into a positive closure
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*
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* synopsis
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* new = mkposcl( state );
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*
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* new - a machine matching the positive closure of "state"
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*/
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int mkposcl( state )
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int state;
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{
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int eps;
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if ( SUPER_FREE_EPSILON(finalst[state]) )
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{
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mkxtion( finalst[state], state );
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return state;
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}
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else
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{
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eps = mkstate( SYM_EPSILON );
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mkxtion( eps, state );
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return link_machines( state, eps );
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}
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}
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/* mkrep - make a replicated machine
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*
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* synopsis
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* new = mkrep( mach, lb, ub );
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*
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* new - a machine that matches whatever "mach" matched from "lb"
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* number of times to "ub" number of times
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*
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* note
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* if "ub" is INFINITY then "new" matches "lb" or more occurrences of "mach"
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*/
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int mkrep( mach, lb, ub )
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int mach, lb, ub;
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{
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int base_mach, tail, copy, i;
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base_mach = copysingl( mach, lb - 1 );
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if ( ub == INFINITY )
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{
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copy = dupmachine( mach );
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mach = link_machines( mach,
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link_machines( base_mach, mkclos( copy ) ) );
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}
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else
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{
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tail = mkstate( SYM_EPSILON );
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for ( i = lb; i < ub; ++i )
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{
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copy = dupmachine( mach );
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tail = mkopt( link_machines( copy, tail ) );
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}
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mach = link_machines( mach, link_machines( base_mach, tail ) );
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}
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return mach;
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}
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/* mkstate - create a state with a transition on a given symbol
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*
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* synopsis
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*
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* state = mkstate( sym );
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*
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* state - a new state matching sym
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* sym - the symbol the new state is to have an out-transition on
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*
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* note that this routine makes new states in ascending order through the
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* state array (and increments LASTNFA accordingly). The routine DUPMACHINE
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* relies on machines being made in ascending order and that they are
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* CONTIGUOUS. Change it and you will have to rewrite DUPMACHINE (kludge
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* that it admittedly is)
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*/
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int mkstate( sym )
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int sym;
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{
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if ( ++lastnfa >= current_mns )
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{
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if ( (current_mns += MNS_INCREMENT) >= MAXIMUM_MNS )
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lerrif(
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_( "input rules are too complicated (>= %d NFA states)" ),
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current_mns );
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++num_reallocs;
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firstst = reallocate_integer_array( firstst, current_mns );
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lastst = reallocate_integer_array( lastst, current_mns );
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finalst = reallocate_integer_array( finalst, current_mns );
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transchar = reallocate_integer_array( transchar, current_mns );
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trans1 = reallocate_integer_array( trans1, current_mns );
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trans2 = reallocate_integer_array( trans2, current_mns );
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accptnum = reallocate_integer_array( accptnum, current_mns );
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assoc_rule =
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reallocate_integer_array( assoc_rule, current_mns );
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state_type =
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reallocate_integer_array( state_type, current_mns );
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}
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firstst[lastnfa] = lastnfa;
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finalst[lastnfa] = lastnfa;
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lastst[lastnfa] = lastnfa;
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transchar[lastnfa] = sym;
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trans1[lastnfa] = NO_TRANSITION;
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trans2[lastnfa] = NO_TRANSITION;
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accptnum[lastnfa] = NIL;
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assoc_rule[lastnfa] = num_rules;
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state_type[lastnfa] = current_state_type;
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/* Fix up equivalence classes base on this transition. Note that any
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* character which has its own transition gets its own equivalence
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* class. Thus only characters which are only in character classes
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* have a chance at being in the same equivalence class. E.g. "a|b"
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* puts 'a' and 'b' into two different equivalence classes. "[ab]"
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* puts them in the same equivalence class (barring other differences
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* elsewhere in the input).
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*/
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if ( sym < 0 )
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{
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/* We don't have to update the equivalence classes since
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* that was already done when the ccl was created for the
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* first time.
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*/
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}
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else if ( sym == SYM_EPSILON )
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++numeps;
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else
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{
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check_char( sym );
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if ( useecs )
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/* Map NUL's to csize. */
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mkechar( sym ? sym : csize, nextecm, ecgroup );
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}
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return lastnfa;
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}
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/* mkxtion - make a transition from one state to another
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*
|
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* synopsis
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*
|
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* mkxtion( statefrom, stateto );
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*
|
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* statefrom - the state from which the transition is to be made
|
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* stateto - the state to which the transition is to be made
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*/
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void mkxtion( statefrom, stateto )
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int statefrom, stateto;
|
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{
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if ( trans1[statefrom] == NO_TRANSITION )
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trans1[statefrom] = stateto;
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else if ( (transchar[statefrom] != SYM_EPSILON) ||
|
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(trans2[statefrom] != NO_TRANSITION) )
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flexfatal( _( "found too many transitions in mkxtion()" ) );
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else
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{ /* second out-transition for an epsilon state */
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++eps2;
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trans2[statefrom] = stateto;
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|
}
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}
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/* new_rule - initialize for a new rule */
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|
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void new_rule()
|
|
{
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|
if ( ++num_rules >= current_max_rules )
|
|
{
|
|
++num_reallocs;
|
|
current_max_rules += MAX_RULES_INCREMENT;
|
|
rule_type = reallocate_integer_array( rule_type,
|
|
current_max_rules );
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rule_linenum = reallocate_integer_array( rule_linenum,
|
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current_max_rules );
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rule_useful = reallocate_integer_array( rule_useful,
|
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current_max_rules );
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}
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if ( num_rules > MAX_RULE )
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|
lerrif( _( "too many rules (> %d)!" ), MAX_RULE );
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|
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|
rule_linenum[num_rules] = linenum;
|
|
rule_useful[num_rules] = false;
|
|
}
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