709 lines
18 KiB
C
709 lines
18 KiB
C
/* nfa - NFA construction routines */
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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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/* This code is derived from software contributed to Berkeley by */
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/* Vern Paxson. */
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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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/* This file is part of flex. */
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/* Redistribution and use in source and binary forms, with or without */
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/* modification, are permitted provided that the following conditions */
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/* are met: */
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/* 1. Redistributions of source code must retain the above copyright */
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/* notice, this list of conditions and the following disclaimer. */
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/* 2. Redistributions in binary form must reproduce the above copyright */
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/* notice, this list of conditions and the following disclaimer in the */
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/* documentation and/or other materials provided with the distribution. */
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/* Neither the name of the University nor the names of its contributors */
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/* may be used to endorse or promote products derived from this software */
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/* without specific prior written permission. */
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/* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR */
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/* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED */
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/* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR */
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/* PURPOSE. */
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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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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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_
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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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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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state = mkstate (transchar[i]);
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if (trans1[i] != NO_TRANSITION) {
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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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pcont_act)
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int mach, variable_trail_rule, headcnt, trailcnt, pcont_act;
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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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/* If the previous rule was continued action, then we inherit the
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* previous newline flag, possibly overriding the current one.
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*/
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if (pcont_act && rule_has_nl[num_rules - 1])
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rule_has_nl[num_rules] = true;
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snprintf (action_text, sizeof(action_text), "case %d:\n", num_rules);
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add_action (action_text);
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if (rule_has_nl[num_rules]) {
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snprintf (action_text, sizeof(action_text), "/* rule %d can match eol */\n",
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num_rules);
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add_action (action_text);
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}
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if (variable_trail_rule) {
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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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_
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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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rule_type[num_rules] = RULE_NORMAL;
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if (headcnt > 0 || trailcnt > 0) {
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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_G(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_G(yy_hold_char); /* undo effects of setting up yytext */\n");
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if (headcnt > 0) {
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snprintf (action_text, sizeof(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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snprintf (action_text, sizeof(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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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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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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if (trans1[mach] != NO_TRANSITION)
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mark_beginning_as_normal (trans1[mach]);
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if (trans2[mach] != NO_TRANSITION)
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mark_beginning_as_normal (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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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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/* 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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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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orend = finalst[second];
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mkxtion (finalst[first], orend);
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}
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else {
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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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mkxtion (finalst[state], state);
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return state;
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}
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else {
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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 INFINITE_REPEAT 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 == INFINITE_REPEAT) {
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copy = dupmachine (mach);
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mach = link_machines (mach,
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link_machines (base_mach,
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mkclos (copy)));
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}
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else {
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tail = mkstate (SYM_EPSILON);
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for (i = lb; i < ub; ++i) {
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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 =
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link_machines (mach,
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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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* note that this routine makes new states in ascending order through the
|
|
* state array (and increments LASTNFA accordingly). The routine DUPMACHINE
|
|
* relies on machines being made in ascending order and that they are
|
|
* CONTIGUOUS. Change it and you will have to rewrite DUPMACHINE (kludge
|
|
* that it admittedly is)
|
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*/
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|
|
|
int mkstate (sym)
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|
int sym;
|
|
{
|
|
if (++lastnfa >= current_mns) {
|
|
if ((current_mns += MNS_INCREMENT) >= maximum_mns)
|
|
lerrif (_
|
|
("input rules are too complicated (>= %d NFA states)"),
|
|
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 =
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|
reallocate_integer_array (transchar, current_mns);
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|
trans1 = reallocate_integer_array (trans1, current_mns);
|
|
trans2 = reallocate_integer_array (trans2, current_mns);
|
|
accptnum =
|
|
reallocate_integer_array (accptnum, current_mns);
|
|
assoc_rule =
|
|
reallocate_integer_array (assoc_rule, current_mns);
|
|
state_type =
|
|
reallocate_integer_array (state_type, current_mns);
|
|
}
|
|
|
|
firstst[lastnfa] = lastnfa;
|
|
finalst[lastnfa] = lastnfa;
|
|
lastst[lastnfa] = lastnfa;
|
|
transchar[lastnfa] = sym;
|
|
trans1[lastnfa] = NO_TRANSITION;
|
|
trans2[lastnfa] = NO_TRANSITION;
|
|
accptnum[lastnfa] = NIL;
|
|
assoc_rule[lastnfa] = num_rules;
|
|
state_type[lastnfa] = current_state_type;
|
|
|
|
/* Fix up equivalence classes base on this transition. Note that any
|
|
* character which has its own transition gets its own equivalence
|
|
* class. Thus only characters which are only in character classes
|
|
* have a chance at being in the same equivalence class. E.g. "a|b"
|
|
* puts 'a' and 'b' into two different equivalence classes. "[ab]"
|
|
* puts them in the same equivalence class (barring other differences
|
|
* elsewhere in the input).
|
|
*/
|
|
|
|
if (sym < 0) {
|
|
/* We don't have to update the equivalence classes since
|
|
* that was already done when the ccl was created for the
|
|
* first time.
|
|
*/
|
|
}
|
|
|
|
else if (sym == SYM_EPSILON)
|
|
++numeps;
|
|
|
|
else {
|
|
check_char (sym);
|
|
|
|
if (useecs)
|
|
/* Map NUL's to csize. */
|
|
mkechar (sym ? sym : csize, nextecm, ecgroup);
|
|
}
|
|
|
|
return lastnfa;
|
|
}
|
|
|
|
|
|
/* mkxtion - make a transition from one state to another
|
|
*
|
|
* synopsis
|
|
*
|
|
* mkxtion( statefrom, stateto );
|
|
*
|
|
* statefrom - the state from which the transition is to be made
|
|
* stateto - the state to which the transition is to be made
|
|
*/
|
|
|
|
void mkxtion (statefrom, stateto)
|
|
int statefrom, stateto;
|
|
{
|
|
if (trans1[statefrom] == NO_TRANSITION)
|
|
trans1[statefrom] = stateto;
|
|
|
|
else if ((transchar[statefrom] != SYM_EPSILON) ||
|
|
(trans2[statefrom] != NO_TRANSITION))
|
|
flexfatal (_("found too many transitions in mkxtion()"));
|
|
|
|
else { /* second out-transition for an epsilon state */
|
|
++eps2;
|
|
trans2[statefrom] = stateto;
|
|
}
|
|
}
|
|
|
|
/* new_rule - initialize for a new rule */
|
|
|
|
void new_rule ()
|
|
{
|
|
if (++num_rules >= current_max_rules) {
|
|
++num_reallocs;
|
|
current_max_rules += MAX_RULES_INCREMENT;
|
|
rule_type = reallocate_integer_array (rule_type,
|
|
current_max_rules);
|
|
rule_linenum = reallocate_integer_array (rule_linenum,
|
|
current_max_rules);
|
|
rule_useful = reallocate_integer_array (rule_useful,
|
|
current_max_rules);
|
|
rule_has_nl = reallocate_bool_array (rule_has_nl,
|
|
current_max_rules);
|
|
}
|
|
|
|
if (num_rules > MAX_RULE)
|
|
lerrif (_("too many rules (> %d)!"), MAX_RULE);
|
|
|
|
rule_linenum[num_rules] = linenum;
|
|
rule_useful[num_rules] = false;
|
|
rule_has_nl[num_rules] = false;
|
|
}
|