/* nfa - NFA construction routines */

/*  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. */

/*  This file is part of flex. */

/*  Redistribution and use in source and binary forms, with or without */

/*  modification, are permitted provided that the following conditions */

/*  are met: */

/*  1. Redistributions of source code must retain the above copyright */

/*     notice, this list of conditions and the following disclaimer. */

/*  2. Redistributions in binary form must reproduce the above copyright */

/*     notice, this list of conditions and the following disclaimer in the */

/*     documentation and/or other materials provided with the distribution. */

/*  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. */

#include "flexdef.h"

/* declare functions that have forward references */

int	dupmachine(int);

void	mkxtion(int, int);

/* add_accept - add an accepting state to a machine

 *

 * accepting_number becomes mach's accepting number.

 */

void    add_accept (int mach, int accepting_number)

{

	/* Hang the accepting number off an epsilon state.  if it is associated

	 * with a state that has a non-epsilon out-transition, then the state

	 * will accept BEFORE it makes that transition, i.e., one character

	 * too soon.

	 */

	if (transchar[finalst[mach]] == SYM_EPSILON)

		accptnum[finalst[mach]] = accepting_number;

	else {

		int     astate = mkstate (SYM_EPSILON);

		accptnum[astate] = accepting_number;

		(void) link_machines (mach, astate);

	}

}

/* copysingl - make a given number of copies of a singleton machine

 *

 * synopsis

 *

 *   newsng = copysingl( singl, num );

 *

 *     newsng - a new singleton composed of num copies of singl

 *     singl  - a singleton machine

 *     num    - the number of copies of singl to be present in newsng

 */

int     copysingl (int singl, int num)

{

	int     copy, i;

	copy = mkstate (SYM_EPSILON);

	for (i = 1; i <= num; ++i)

		copy = link_machines (copy, dupmachine (singl));

	return copy;

}

/* dumpnfa - debugging routine to write out an nfa */

void    dumpnfa (int state1)

{

	int     sym, tsp1, tsp2, anum, ns;

	fprintf (stderr,

		 _

		 ("\n\n********** beginning dump of nfa with start state %d\n"),

		 state1);

	/* We probably should loop starting at firstst[state1] and going to

	 * lastst[state1], but they're not maintained properly when we "or"

	 * all of the rules together.  So we use our knowledge that the machine

	 * starts at state 1 and ends at lastnfa.

	 */

	/* for ( ns = firstst[state1]; ns <= lastst[state1]; ++ns ) */

	for (ns = 1; ns <= lastnfa; ++ns) {

		fprintf (stderr, _("state # %4d\t"), ns);

		sym = transchar[ns];

		tsp1 = trans1[ns];

		tsp2 = trans2[ns];

		anum = accptnum[ns];

		fprintf (stderr, "%3d:  %4d, %4d", sym, tsp1, tsp2);

		if (anum != NIL)

			fprintf (stderr, "  [%d]", anum);

		fprintf (stderr, "\n");

	}

	fprintf (stderr, _("********** end of dump\n"));

}

/* dupmachine - make a duplicate of a given machine

 *

 * synopsis

 *

 *   copy = dupmachine( mach );

 *

 *     copy - holds duplicate of mach

 *     mach - machine to be duplicated

 *

 * note that the copy of mach is NOT an exact duplicate; rather, all the

 * transition states values are adjusted so that the copy is self-contained,

 * as the original should have been.

 *

 * also note that the original MUST be contiguous, with its low and high

 * states accessible by the arrays firstst and lastst

 */

int     dupmachine (int mach)

{

	int     i, init, state_offset;

	int     state = 0;

	int     last = lastst[mach];

	for (i = firstst[mach]; i <= last; ++i) {

		state = mkstate (transchar[i]);

		if (trans1[i] != NO_TRANSITION) {

			mkxtion (finalst[state], trans1[i] + state - i);

			if (transchar[i] == SYM_EPSILON &&

			    trans2[i] != NO_TRANSITION)

					mkxtion (finalst[state],

						 trans2[i] + state - i);

		}

		accptnum[state] = accptnum[i];

	}

	if (state == 0)

		flexfatal (_("empty machine in dupmachine()"));

	state_offset = state - i + 1;

	init = mach + state_offset;

	firstst[init] = firstst[mach] + state_offset;

	finalst[init] = finalst[mach] + state_offset;

	lastst[init] = lastst[mach] + state_offset;

	return init;

}

/* finish_rule - finish up the processing for a rule

 *

 * An accepting number is added to the given machine.  If variable_trail_rule

 * is true then the rule has trailing context and both the head and trail

 * are variable size.  Otherwise if headcnt or trailcnt is non-zero then

 * the machine recognizes a pattern with trailing context and headcnt is

 * the number of characters in the matched part of the pattern, or zero

 * if the matched part has variable length.  trailcnt is the number of

 * trailing context characters in the pattern, or zero if the trailing

 * context has variable length.

 */

void    finish_rule (int mach, int variable_trail_rule, int headcnt, int trailcnt,

		     int pcont_act)

{

	char    action_text[MAXLINE];

	add_accept (mach, num_rules);

	/* We did this in new_rule(), but it often gets the wrong

	 * number because we do it before we start parsing the current rule.

	 */

	rule_linenum[num_rules] = linenum;

	/* If this is a continued action, then the line-number has already

	 * been updated, giving us the wrong number.

	 */

	if (continued_action)

		--rule_linenum[num_rules];

	/* If the previous rule was continued action, then we inherit the

	 * previous newline flag, possibly overriding the current one.

	 */

	if (pcont_act && rule_has_nl[num_rules - 1])

		rule_has_nl[num_rules] = true;

	snprintf (action_text, sizeof(action_text), "case %d:\n", num_rules);

	add_action (action_text);

	if (rule_has_nl[num_rules]) {

		snprintf (action_text, sizeof(action_text), "/* rule %d can match eol */\n",

			 num_rules);

		add_action (action_text);

	}

	if (variable_trail_rule) {

		rule_type[num_rules] = RULE_VARIABLE;

		if (performance_report > 0)

			fprintf (stderr,

				 _

				 ("Variable trailing context rule at line %d\n"),

				 rule_linenum[num_rules]);

		variable_trailing_context_rules = true;

	}

	else {

		rule_type[num_rules] = RULE_NORMAL;

		if (headcnt > 0 || trailcnt > 0) {

			/* Do trailing context magic to not match the trailing

			 * characters.

			 */

			char   *scanner_cp = "YY_G(yy_c_buf_p) = yy_cp";

			char   *scanner_bp = "yy_bp";

			add_action

				("*yy_cp = YY_G(yy_hold_char); /* undo effects of setting up yytext */\n");

			if (headcnt > 0) {

				if (rule_has_nl[num_rules]) {

					snprintf (action_text, sizeof(action_text),

						"YY_LINENO_REWIND_TO(%s + %d);\n", scanner_bp, headcnt);

					add_action (action_text);

				}

				snprintf (action_text, sizeof(action_text), "%s = %s + %d;\n",

					 scanner_cp, scanner_bp, headcnt);

				add_action (action_text);

			}

			else {

				if (rule_has_nl[num_rules]) {

					snprintf (action_text, sizeof(action_text),

						 "YY_LINENO_REWIND_TO(yy_cp - %d);\n", trailcnt);

					add_action (action_text);

				}

				snprintf (action_text, sizeof(action_text), "%s -= %d;\n",

					 scanner_cp, trailcnt);

				add_action (action_text);

			}

			add_action

				("YY_DO_BEFORE_ACTION; /* set up yytext again */\n");

		}

	}

	/* Okay, in the action code at this point yytext and yyleng have

	 * their proper final values for this rule, so here's the point

	 * to do any user action.  But don't do it for continued actions,

	 * as that'll result in multiple YY_RULE_SETUP's.

	 */

	if (!continued_action)

		add_action ("YY_RULE_SETUP\n");

	line_directive_out(NULL, 1);

}

/* link_machines - connect two machines together

 *

 * synopsis

 *

 *   new = link_machines( first, last );

 *

 *     new    - a machine constructed by connecting first to last

 *     first  - the machine whose successor is to be last

 *     last   - the machine whose predecessor is to be first

 *

 * note: this routine concatenates the machine first with the machine

 *  last to produce a machine new which will pattern-match first first

 *  and then last, and will fail if either of the sub-patterns fails.

 *  FIRST is set to new by the operation.  last is unmolested.

 */

int     link_machines (int first, int last)

{

	if (first == NIL)

		return last;

	else if (last == NIL)

		return first;

	else {

		mkxtion (finalst[first], last);

		finalst[first] = finalst[last];

		lastst[first] = MAX (lastst[first], lastst[last]);

		firstst[first] = MIN (firstst[first], firstst[last]);

		return first;

	}

}

/* mark_beginning_as_normal - mark each "beginning" state in a machine

 *                            as being a "normal" (i.e., not trailing context-

 *                            associated) states

 *

 * The "beginning" states are the epsilon closure of the first state

 */

void    mark_beginning_as_normal (int mach)

{

	switch (state_type[mach]) {

	case STATE_NORMAL:

		/* Oh, we've already visited here. */

		return;

	case STATE_TRAILING_CONTEXT:

		state_type[mach] = STATE_NORMAL;

		if (transchar[mach] == SYM_EPSILON) {

			if (trans1[mach] != NO_TRANSITION)

				mark_beginning_as_normal (trans1[mach]);

			if (trans2[mach] != NO_TRANSITION)

				mark_beginning_as_normal (trans2[mach]);

		}

		break;

	default:

		flexerror (_

			   ("bad state type in mark_beginning_as_normal()"));

		break;

	}

}

/* mkbranch - make a machine that branches to two machines

 *

 * synopsis

 *

 *   branch = mkbranch( first, second );

 *

 *     branch - a machine which matches either first's pattern or second's

 *     first, second - machines whose patterns are to be or'ed (the | operator)

 *

 * Note that first and second are NEITHER destroyed by the operation.  Also,

 * the resulting machine CANNOT be used with any other "mk" operation except

 * more mkbranch's.  Compare with mkor()

 */

int     mkbranch (int first, int second)

{

	int     eps;

	if (first == NO_TRANSITION)

		return second;

	else if (second == NO_TRANSITION)

		return first;

	eps = mkstate (SYM_EPSILON);

	mkxtion (eps, first);

	mkxtion (eps, second);

	return eps;

}

/* mkclos - convert a machine into a closure

 *

 * synopsis

 *   new = mkclos( state );

 *

 * new - a new state which matches the closure of "state"

 */

int     mkclos (int state)

{

	return mkopt (mkposcl (state));

}

/* mkopt - make a machine optional

 *

 * synopsis

 *

 *   new = mkopt( mach );

 *

 *     new  - a machine which optionally matches whatever mach matched

 *     mach - the machine to make optional

 *

 * notes:

 *     1. mach must be the last machine created

 *     2. mach is destroyed by the call

 */

int     mkopt (int mach)

{

	int     eps;

	if (!SUPER_FREE_EPSILON (finalst[mach])) {

		eps = mkstate (SYM_EPSILON);

		mach = link_machines (mach, eps);

	}

	/* Can't skimp on the following if FREE_EPSILON(mach) is true because

	 * some state interior to "mach" might point back to the beginning

	 * for a closure.

	 */

	eps = mkstate (SYM_EPSILON);

	mach = link_machines (eps, mach);

	mkxtion (mach, finalst[mach]);

	return mach;

}

/* mkor - make a machine that matches either one of two machines

 *

 * synopsis

 *

 *   new = mkor( first, second );

 *

 *     new - a machine which matches either first's pattern or second's

 *     first, second - machines whose patterns are to be or'ed (the | operator)

 *

 * note that first and second are both destroyed by the operation

 * the code is rather convoluted because an attempt is made to minimize

 * the number of epsilon states needed

 */

int     mkor (int first, int second)

{

	int     eps, orend;

	if (first == NIL)

		return second;

	else if (second == NIL)

		return first;

	else {

		/* See comment in mkopt() about why we can't use the first

		 * state of "first" or "second" if they satisfy "FREE_EPSILON".

		 */

		eps = mkstate (SYM_EPSILON);

		first = link_machines (eps, first);

		mkxtion (first, second);

		if (SUPER_FREE_EPSILON (finalst[first]) &&

		    accptnum[finalst[first]] == NIL) {

			orend = finalst[first];

			mkxtion (finalst[second], orend);

		}

		else if (SUPER_FREE_EPSILON (finalst[second]) &&

			 accptnum[finalst[second]] == NIL) {

			orend = finalst[second];

			mkxtion (finalst[first], orend);

		}

		else {

			eps = mkstate (SYM_EPSILON);

			first = link_machines (first, eps);

			orend = finalst[first];

			mkxtion (finalst[second], orend);

		}

	}

	finalst[first] = orend;

	return first;

}

/* mkposcl - convert a machine into a positive closure

 *

 * synopsis

 *   new = mkposcl( state );

 *

 *    new - a machine matching the positive closure of "state"

 */

int     mkposcl (int state)

{

	int     eps;

	if (SUPER_FREE_EPSILON (finalst[state])) {

		mkxtion (finalst[state], state);

		return state;

	}

	else {

		eps = mkstate (SYM_EPSILON);

		mkxtion (eps, state);

		return link_machines (state, eps);

	}

}

/* mkrep - make a replicated machine

 *

 * synopsis

 *   new = mkrep( mach, lb, ub );

 *

 *    new - a machine that matches whatever "mach" matched from "lb"

 *          number of times to "ub" number of times

 *

 * note

 *   if "ub" is INFINITE_REPEAT then "new" matches "lb" or more occurrences of "mach"

 */

int     mkrep (int mach, int lb, int ub)

{

	int     base_mach, tail, copy, i;

	base_mach = copysingl (mach, lb - 1);

	if (ub == INFINITE_REPEAT) {

		copy = dupmachine (mach);

		mach = link_machines (mach,

				      link_machines (base_mach,

						     mkclos (copy)));

	}

	else {

		tail = mkstate (SYM_EPSILON);

		for (i = lb; i < ub; ++i) {

			copy = dupmachine (mach);

			tail = mkopt (link_machines (copy, tail));

		}

		mach =

			link_machines (mach,

				       link_machines (base_mach, tail));

	}

	return mach;

}

/* mkstate - create a state with a transition on a given symbol

 *

 * synopsis

 *

 *   state = mkstate( sym );

 *

 *     state - a new state matching sym

 *     sym   - the symbol the new state is to have an out-transition on

 *

 * 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)

 */

int     mkstate (int sym)

{

	if (++lastnfa >= current_mns) {

		if ((current_mns += MNS_INCREMENT) >= maximum_mns)

			lerr(_

				("input rules are too complicated (>= %d NFA states)"),

current_mns);

		++num_reallocs;

		firstst = reallocate_integer_array (firstst, current_mns);

		lastst = reallocate_integer_array (lastst, current_mns);

		finalst = reallocate_integer_array (finalst, current_mns);

		transchar =

			reallocate_integer_array (transchar, current_mns);

		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 (int statefrom, int 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 (void)

{

	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)

		lerr (_("too many rules (> %d)!"), MAX_RULE);

	rule_linenum[num_rules] = linenum;

	rule_useful[num_rules] = false;

	rule_has_nl[num_rules] = false;

}