source: trunk/third/flex/dfa.c @ 16044

/* dfa - DFA 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.
 *
 * Redistribution and use in source and binary forms with or without
 * modification are permitted provided that: (1) source distributions retain
 * this entire copyright notice and comment, and (2) distributions including
 * binaries display the following acknowledgement:  ``This product includes
 * software developed by the University of California, Berkeley and its
 * contributors'' in the documentation or other materials provided with the
 * distribution and in all advertising materials mentioning features or use
 * of this software.  Neither the name of the University nor the names of
 * its contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/* $Header: /afs/dev.mit.edu/source/repository/third/flex/dfa.c,v 1.1.1.1 2001-04-10 17:05:14 ghudson Exp $ */

#include "flexdef.h"


/* declare functions that have forward references */

void dump_associated_rules PROTO((FILE*, int));
void dump_transitions PROTO((FILE*, int[]));
void sympartition PROTO((int[], int, int[], int[]));
int symfollowset PROTO((int[], int, int, int[]));


/* check_for_backing_up - check a DFA state for backing up
 *
 * synopsis
 *     void check_for_backing_up( int ds, int state[numecs] );
 *
 * ds is the number of the state to check and state[] is its out-transitions,
 * indexed by equivalence class.
 */

void check_for_backing_up( ds, state )
int ds;
int state[];
        {
        if ( (reject && ! dfaacc[ds].dfaacc_set) ||
             (! reject && ! dfaacc[ds].dfaacc_state) )
                { /* state is non-accepting */
                ++num_backing_up;

                if ( backing_up_report )
                        {
                        fprintf( backing_up_file,
                                _( "State #%d is non-accepting -\n" ), ds );

                        /* identify the state */
                        dump_associated_rules( backing_up_file, ds );

                        /* Now identify it further using the out- and
                         * jam-transitions.
                         */
                        dump_transitions( backing_up_file, state );

                        putc( '\n', backing_up_file );
                        }
                }
        }


/* check_trailing_context - check to see if NFA state set constitutes
 *                          "dangerous" trailing context
 *
 * synopsis
 *    void check_trailing_context( int nfa_states[num_states+1], int num_states,
 *                              int accset[nacc+1], int nacc );
 *
 * NOTES
 *  Trailing context is "dangerous" if both the head and the trailing
 *  part are of variable size \and/ there's a DFA state which contains
 *  both an accepting state for the head part of the rule and NFA states
 *  which occur after the beginning of the trailing context.
 *
 *  When such a rule is matched, it's impossible to tell if having been
 *  in the DFA state indicates the beginning of the trailing context or
 *  further-along scanning of the pattern.  In these cases, a warning
 *  message is issued.
 *
 *    nfa_states[1 .. num_states] is the list of NFA states in the DFA.
 *    accset[1 .. nacc] is the list of accepting numbers for the DFA state.
 */

void check_trailing_context( nfa_states, num_states, accset, nacc )
int *nfa_states, num_states;
int *accset;
int nacc;
        {
        register int i, j;

        for ( i = 1; i <= num_states; ++i )
                {
                int ns = nfa_states[i];
                register int type = state_type[ns];
                register int ar = assoc_rule[ns];

                if ( type == STATE_NORMAL || rule_type[ar] != RULE_VARIABLE )
                        { /* do nothing */
                        }

                else if ( type == STATE_TRAILING_CONTEXT )
                        {
                        /* Potential trouble.  Scan set of accepting numbers
                         * for the one marking the end of the "head".  We
                         * assume that this looping will be fairly cheap
                         * since it's rare that an accepting number set
                         * is large.
                         */
                        for ( j = 1; j <= nacc; ++j )
                                if ( accset[j] & YY_TRAILING_HEAD_MASK )
                                        {
                                        line_warning(
                                        _( "dangerous trailing context" ),
                                                rule_linenum[ar] );
                                        return;
                                        }
                        }
                }
        }


/* dump_associated_rules - list the rules associated with a DFA state
 *
 * Goes through the set of NFA states associated with the DFA and
 * extracts the first MAX_ASSOC_RULES unique rules, sorts them,
 * and writes a report to the given file.
 */

void dump_associated_rules( file, ds )
FILE *file;
int ds;
        {
        register int i, j;
        register int num_associated_rules = 0;
        int rule_set[MAX_ASSOC_RULES + 1];
        int *dset = dss[ds];
        int size = dfasiz[ds];

        for ( i = 1; i <= size; ++i )
                {
                register int rule_num = rule_linenum[assoc_rule[dset[i]]];

                for ( j = 1; j <= num_associated_rules; ++j )
                        if ( rule_num == rule_set[j] )
                                break;

                if ( j > num_associated_rules )
                        { /* new rule */
                        if ( num_associated_rules < MAX_ASSOC_RULES )
                                rule_set[++num_associated_rules] = rule_num;
                        }
                }

        bubble( rule_set, num_associated_rules );

        fprintf( file, _( " associated rule line numbers:" ) );

        for ( i = 1; i <= num_associated_rules; ++i )
                {
                if ( i % 8 == 1 )
                        putc( '\n', file );

                fprintf( file, "\t%d", rule_set[i] );
                }

        putc( '\n', file );
        }


/* dump_transitions - list the transitions associated with a DFA state
 *
 * synopsis
 *     dump_transitions( FILE *file, int state[numecs] );
 *
 * Goes through the set of out-transitions and lists them in human-readable
 * form (i.e., not as equivalence classes); also lists jam transitions
 * (i.e., all those which are not out-transitions, plus EOF).  The dump
 * is done to the given file.
 */

void dump_transitions( file, state )
FILE *file;
int state[];
        {
        register int i, ec;
        int out_char_set[CSIZE];

        for ( i = 0; i < csize; ++i )
                {
                ec = ABS( ecgroup[i] );
                out_char_set[i] = state[ec];
                }

        fprintf( file, _( " out-transitions: " ) );

        list_character_set( file, out_char_set );

        /* now invert the members of the set to get the jam transitions */
        for ( i = 0; i < csize; ++i )
                out_char_set[i] = ! out_char_set[i];

        fprintf( file, _( "\n jam-transitions: EOF " ) );

        list_character_set( file, out_char_set );

        putc( '\n', file );
        }


/* epsclosure - construct the epsilon closure of a set of ndfa states
 *
 * synopsis
 *    int *epsclosure( int t[num_states], int *numstates_addr,
 *                      int accset[num_rules+1], int *nacc_addr,
 *                      int *hashval_addr );
 *
 * NOTES
 *  The epsilon closure is the set of all states reachable by an arbitrary
 *  number of epsilon transitions, which themselves do not have epsilon
 *  transitions going out, unioned with the set of states which have non-null
 *  accepting numbers.  t is an array of size numstates of nfa state numbers.
 *  Upon return, t holds the epsilon closure and *numstates_addr is updated.
 *  accset holds a list of the accepting numbers, and the size of accset is
 *  given by *nacc_addr.  t may be subjected to reallocation if it is not
 *  large enough to hold the epsilon closure.
 *
 *  hashval is the hash value for the dfa corresponding to the state set.
 */

int *epsclosure( t, ns_addr, accset, nacc_addr, hv_addr )
int *t, *ns_addr, accset[], *nacc_addr, *hv_addr;
        {
        register int stkpos, ns, tsp;
        int numstates = *ns_addr, nacc, hashval, transsym, nfaccnum;
        int stkend, nstate;
        static int did_stk_init = false, *stk; 

#define MARK_STATE(state) \
trans1[state] = trans1[state] - MARKER_DIFFERENCE;

#define IS_MARKED(state) (trans1[state] < 0)

#define UNMARK_STATE(state) \
trans1[state] = trans1[state] + MARKER_DIFFERENCE;

#define CHECK_ACCEPT(state) \
{ \
nfaccnum = accptnum[state]; \
if ( nfaccnum != NIL ) \
accset[++nacc] = nfaccnum; \
}

#define DO_REALLOCATION \
{ \
current_max_dfa_size += MAX_DFA_SIZE_INCREMENT; \
++num_reallocs; \
t = reallocate_integer_array( t, current_max_dfa_size ); \
stk = reallocate_integer_array( stk, current_max_dfa_size ); \
} \

#define PUT_ON_STACK(state) \
{ \
if ( ++stkend >= current_max_dfa_size ) \
DO_REALLOCATION \
stk[stkend] = state; \
MARK_STATE(state) \
}

#define ADD_STATE(state) \
{ \
if ( ++numstates >= current_max_dfa_size ) \
DO_REALLOCATION \
t[numstates] = state; \
hashval += state; \
}

#define STACK_STATE(state) \
{ \
PUT_ON_STACK(state) \
CHECK_ACCEPT(state) \
if ( nfaccnum != NIL || transchar[state] != SYM_EPSILON ) \
ADD_STATE(state) \
}


        if ( ! did_stk_init )
                {
                stk = allocate_integer_array( current_max_dfa_size );
                did_stk_init = true;
                }

        nacc = stkend = hashval = 0;

        for ( nstate = 1; nstate <= numstates; ++nstate )
                {
                ns = t[nstate];

                /* The state could be marked if we've already pushed it onto
                 * the stack.
                 */
                if ( ! IS_MARKED(ns) )
                        {
                        PUT_ON_STACK(ns)
                        CHECK_ACCEPT(ns)
                        hashval += ns;
                        }
                }

        for ( stkpos = 1; stkpos <= stkend; ++stkpos )
                {
                ns = stk[stkpos];
                transsym = transchar[ns];

                if ( transsym == SYM_EPSILON )
                        {
                        tsp = trans1[ns] + MARKER_DIFFERENCE;

                        if ( tsp != NO_TRANSITION )
                                {
                                if ( ! IS_MARKED(tsp) )
                                        STACK_STATE(tsp)

                                tsp = trans2[ns];

                                if ( tsp != NO_TRANSITION && ! IS_MARKED(tsp) )
                                        STACK_STATE(tsp)
                                }
                        }
                }

        /* Clear out "visit" markers. */

        for ( stkpos = 1; stkpos <= stkend; ++stkpos )
                {
                if ( IS_MARKED(stk[stkpos]) )
                        UNMARK_STATE(stk[stkpos])
                else
                        flexfatal(
                        _( "consistency check failed in epsclosure()" ) );
                }

        *ns_addr = numstates;
        *hv_addr = hashval;
        *nacc_addr = nacc;

        return t;
        }


/* increase_max_dfas - increase the maximum number of DFAs */

void increase_max_dfas()
        {
        current_max_dfas += MAX_DFAS_INCREMENT;

        ++num_reallocs;

        base = reallocate_integer_array( base, current_max_dfas );
        def = reallocate_integer_array( def, current_max_dfas );
        dfasiz = reallocate_integer_array( dfasiz, current_max_dfas );
        accsiz = reallocate_integer_array( accsiz, current_max_dfas );
        dhash = reallocate_integer_array( dhash, current_max_dfas );
        dss = reallocate_int_ptr_array( dss, current_max_dfas );
        dfaacc = reallocate_dfaacc_union( dfaacc, current_max_dfas );

        if ( nultrans )
                nultrans =
                        reallocate_integer_array( nultrans, current_max_dfas );
        }


/* ntod - convert an ndfa to a dfa
 *
 * Creates the dfa corresponding to the ndfa we've constructed.  The
 * dfa starts out in state #1.
 */

void ntod()
        {
        int *accset, ds, nacc, newds;
        int sym, hashval, numstates, dsize;
        int num_full_table_rows;        /* used only for -f */
        int *nset, *dset;
        int targptr, totaltrans, i, comstate, comfreq, targ;
        int symlist[CSIZE + 1];
        int num_start_states;
        int todo_head, todo_next;

        /* Note that the following are indexed by *equivalence classes*
         * and not by characters.  Since equivalence classes are indexed
         * beginning with 1, even if the scanner accepts NUL's, this
         * means that (since every character is potentially in its own
         * equivalence class) these arrays must have room for indices
         * from 1 to CSIZE, so their size must be CSIZE + 1.
         */
        int duplist[CSIZE + 1], state[CSIZE + 1];
        int targfreq[CSIZE + 1], targstate[CSIZE + 1];

        accset = allocate_integer_array( num_rules + 1 );
        nset = allocate_integer_array( current_max_dfa_size );

        /* The "todo" queue is represented by the head, which is the DFA
         * state currently being processed, and the "next", which is the
         * next DFA state number available (not in use).  We depend on the
         * fact that snstods() returns DFA's \in increasing order/, and thus
         * need only know the bounds of the dfas to be processed.
         */
        todo_head = todo_next = 0;

        for ( i = 0; i <= csize; ++i )
                {
                duplist[i] = NIL;
                symlist[i] = false;
                }

        for ( i = 0; i <= num_rules; ++i )
                accset[i] = NIL;

        if ( trace )
                {
                dumpnfa( scset[1] );
                fputs( _( "\n\nDFA Dump:\n\n" ), stderr );
                }

        inittbl();

        /* Check to see whether we should build a separate table for
         * transitions on NUL characters.  We don't do this for full-speed
         * (-F) scanners, since for them we don't have a simple state
         * number lying around with which to index the table.  We also
         * don't bother doing it for scanners unless (1) NUL is in its own
         * equivalence class (indicated by a positive value of
         * ecgroup[NUL]), (2) NUL's equivalence class is the last
         * equivalence class, and (3) the number of equivalence classes is
         * the same as the number of characters.  This latter case comes
         * about when useecs is false or when it's true but every character
         * still manages to land in its own class (unlikely, but it's
         * cheap to check for).  If all these things are true then the
         * character code needed to represent NUL's equivalence class for
         * indexing the tables is going to take one more bit than the
         * number of characters, and therefore we won't be assured of
         * being able to fit it into a YY_CHAR variable.  This rules out
         * storing the transitions in a compressed table, since the code
         * for interpreting them uses a YY_CHAR variable (perhaps it
         * should just use an integer, though; this is worth pondering ...
         * ###).
         *
         * Finally, for full tables, we want the number of entries in the
         * table to be a power of two so the array references go fast (it
         * will just take a shift to compute the major index).  If
         * encoding NUL's transitions in the table will spoil this, we
         * give it its own table (note that this will be the case if we're
         * not using equivalence classes).
         */

        /* Note that the test for ecgroup[0] == numecs below accomplishes
         * both (1) and (2) above
         */
        if ( ! fullspd && ecgroup[0] == numecs )
                {
                /* NUL is alone in its equivalence class, which is the
                 * last one.
                 */
                int use_NUL_table = (numecs == csize);

                if ( fulltbl && ! use_NUL_table )
                        {
                        /* We still may want to use the table if numecs
                         * is a power of 2.
                         */
                        int power_of_two;

                        for ( power_of_two = 1; power_of_two <= csize;
                              power_of_two *= 2 )
                                if ( numecs == power_of_two )
                                        {
                                        use_NUL_table = true;
                                        break;
                                        }
                        }

                if ( use_NUL_table )
                        nultrans = allocate_integer_array( current_max_dfas );

                /* From now on, nultrans != nil indicates that we're
                 * saving null transitions for later, separate encoding.
                 */
                }


        if ( fullspd )
                {
                for ( i = 0; i <= numecs; ++i )
                        state[i] = 0;

                place_state( state, 0, 0 );
                dfaacc[0].dfaacc_state = 0;
                }

        else if ( fulltbl )
                {
                if ( nultrans )
                        /* We won't be including NUL's transitions in the
                         * table, so build it for entries from 0 .. numecs - 1.
                         */
                        num_full_table_rows = numecs;

                else
                        /* Take into account the fact that we'll be including
                         * the NUL entries in the transition table.  Build it
                         * from 0 .. numecs.
                         */
                        num_full_table_rows = numecs + 1;

                /* Unless -Ca, declare it "short" because it's a real
                 * long-shot that that won't be large enough.
                 */
                out_str_dec( "static yyconst %s yy_nxt[][%d] =\n    {\n",
                        /* '}' so vi doesn't get too confused */
                        long_align ? "long" : "short", num_full_table_rows );

                outn( "    {" );

                /* Generate 0 entries for state #0. */
                for ( i = 0; i < num_full_table_rows; ++i )
                        mk2data( 0 );

                dataflush();
                outn( "    },\n" );
                }

        /* Create the first states. */

        num_start_states = lastsc * 2;

        for ( i = 1; i <= num_start_states; ++i )
                {
                numstates = 1;

                /* For each start condition, make one state for the case when
                 * we're at the beginning of the line (the '^' operator) and
                 * one for the case when we're not.
                 */
                if ( i % 2 == 1 )
                        nset[numstates] = scset[(i / 2) + 1];
                else
                        nset[numstates] =
                                mkbranch( scbol[i / 2], scset[i / 2] );

                nset = epsclosure( nset, &numstates, accset, &nacc, &hashval );

                if ( snstods( nset, numstates, accset, nacc, hashval, &ds ) )
                        {
                        numas += nacc;
                        totnst += numstates;
                        ++todo_next;

                        if ( variable_trailing_context_rules && nacc > 0 )
                                check_trailing_context( nset, numstates,
                                                        accset, nacc );
                        }
                }

        if ( ! fullspd )
                {
                if ( ! snstods( nset, 0, accset, 0, 0, &end_of_buffer_state ) )
                        flexfatal(
                        _( "could not create unique end-of-buffer state" ) );

                ++numas;
                ++num_start_states;
                ++todo_next;
                }

        while ( todo_head < todo_next )
                {
                targptr = 0;
                totaltrans = 0;

                for ( i = 1; i <= numecs; ++i )
                        state[i] = 0;

                ds = ++todo_head;

                dset = dss[ds];
                dsize = dfasiz[ds];

                if ( trace )
                        fprintf( stderr, _( "state # %d:\n" ), ds );

                sympartition( dset, dsize, symlist, duplist );

                for ( sym = 1; sym <= numecs; ++sym )
                        {
                        if ( symlist[sym] )
                                {
                                symlist[sym] = 0;

                                if ( duplist[sym] == NIL )
                                        {
                                        /* Symbol has unique out-transitions. */
                                        numstates = symfollowset( dset, dsize,
                                                                sym, nset );
                                        nset = epsclosure( nset, &numstates,
                                                accset, &nacc, &hashval );

                                        if ( snstods( nset, numstates, accset,
                                                nacc, hashval, &newds ) )
                                                {
                                                totnst = totnst + numstates;
                                                ++todo_next;
                                                numas += nacc;

                                                if (
                                        variable_trailing_context_rules &&
                                                        nacc > 0 )
                                                        check_trailing_context(
                                                                nset, numstates,
                                                                accset, nacc );
                                                }

                                        state[sym] = newds;

                                        if ( trace )
                                                fprintf( stderr, "\t%d\t%d\n",
                                                        sym, newds );

                                        targfreq[++targptr] = 1;
                                        targstate[targptr] = newds;
                                        ++numuniq;
                                        }

                                else
                                        {
                                        /* sym's equivalence class has the same
                                         * transitions as duplist(sym)'s
                                         * equivalence class.
                                         */
                                        targ = state[duplist[sym]];
                                        state[sym] = targ;

                                        if ( trace )
                                                fprintf( stderr, "\t%d\t%d\n",
                                                        sym, targ );

                                        /* Update frequency count for
                                         * destination state.
                                         */

                                        i = 0;
                                        while ( targstate[++i] != targ )
                                                ;

                                        ++targfreq[i];
                                        ++numdup;
                                        }

                                ++totaltrans;
                                duplist[sym] = NIL;
                                }
                        }

                if ( caseins && ! useecs )
                        {
                        register int j;

                        for ( i = 'A', j = 'a'; i <= 'Z'; ++i, ++j )
                                {
                                if ( state[i] == 0 && state[j] != 0 )
                                        /* We're adding a transition. */
                                        ++totaltrans;

                                else if ( state[i] != 0 && state[j] == 0 )
                                        /* We're taking away a transition. */
                                        --totaltrans;

                                state[i] = state[j];
                                }
                        }

                numsnpairs += totaltrans;

                if ( ds > num_start_states )
                        check_for_backing_up( ds, state );

                if ( nultrans )
                        {
                        nultrans[ds] = state[NUL_ec];
                        state[NUL_ec] = 0;      /* remove transition */
                        }

                if ( fulltbl )
                        {
                        outn( "    {" );

                        /* Supply array's 0-element. */
                        if ( ds == end_of_buffer_state )
                                mk2data( -end_of_buffer_state );
                        else
                                mk2data( end_of_buffer_state );

                        for ( i = 1; i < num_full_table_rows; ++i )
                                /* Jams are marked by negative of state
                                 * number.
                                 */
                                mk2data( state[i] ? state[i] : -ds );

                        dataflush();
                        outn( "    },\n" );
                        }

                else if ( fullspd )
                        place_state( state, ds, totaltrans );

                else if ( ds == end_of_buffer_state )
                        /* Special case this state to make sure it does what
                         * it's supposed to, i.e., jam on end-of-buffer.
                         */
                        stack1( ds, 0, 0, JAMSTATE );

                else /* normal, compressed state */
                        {
                        /* Determine which destination state is the most
                         * common, and how many transitions to it there are.
                         */

                        comfreq = 0;
                        comstate = 0;

                        for ( i = 1; i <= targptr; ++i )
                                if ( targfreq[i] > comfreq )
                                        {
                                        comfreq = targfreq[i];
                                        comstate = targstate[i];
                                        }

                        bldtbl( state, ds, totaltrans, comstate, comfreq );
                        }
                }

        if ( fulltbl )
                dataend();

        else if ( ! fullspd )
                {
                cmptmps();  /* create compressed template entries */

                /* Create tables for all the states with only one
                 * out-transition.
                 */
                while ( onesp > 0 )
                        {
                        mk1tbl( onestate[onesp], onesym[onesp], onenext[onesp],
                        onedef[onesp] );
                        --onesp;
                        }

                mkdeftbl();
                }

        flex_free( (void *) accset );
        flex_free( (void *) nset );
        }


/* snstods - converts a set of ndfa states into a dfa state
 *
 * synopsis
 *    is_new_state = snstods( int sns[numstates], int numstates,
 *                              int accset[num_rules+1], int nacc,
 *                              int hashval, int *newds_addr );
 *
 * On return, the dfa state number is in newds.
 */

int snstods( sns, numstates, accset, nacc, hashval, newds_addr )
int sns[], numstates, accset[], nacc, hashval, *newds_addr;
        {
        int didsort = 0;
        register int i, j;
        int newds, *oldsns;

        for ( i = 1; i <= lastdfa; ++i )
                if ( hashval == dhash[i] )
                        {
                        if ( numstates == dfasiz[i] )
                                {
                                oldsns = dss[i];

                                if ( ! didsort )
                                        {
                                        /* We sort the states in sns so we
                                         * can compare it to oldsns quickly.
                                         * We use bubble because there probably
                                         * aren't very many states.
                                         */
                                        bubble( sns, numstates );
                                        didsort = 1;
                                        }

                                for ( j = 1; j <= numstates; ++j )
                                        if ( sns[j] != oldsns[j] )
                                                break;

                                if ( j > numstates )
                                        {
                                        ++dfaeql;
                                        *newds_addr = i;
                                        return 0;
                                        }

                                ++hshcol;
                                }

                        else
                                ++hshsave;
                        }

        /* Make a new dfa. */

        if ( ++lastdfa >= current_max_dfas )
                increase_max_dfas();

        newds = lastdfa;

        dss[newds] = allocate_integer_array( numstates + 1 );

        /* If we haven't already sorted the states in sns, we do so now,
         * so that future comparisons with it can be made quickly.
         */

        if ( ! didsort )
                bubble( sns, numstates );

        for ( i = 1; i <= numstates; ++i )
                dss[newds][i] = sns[i];

        dfasiz[newds] = numstates;
        dhash[newds] = hashval;

        if ( nacc == 0 )
                {
                if ( reject )
                        dfaacc[newds].dfaacc_set = (int *) 0;
                else
                        dfaacc[newds].dfaacc_state = 0;

                accsiz[newds] = 0;
                }

        else if ( reject )
                {
                /* We sort the accepting set in increasing order so the
                 * disambiguating rule that the first rule listed is considered
                 * match in the event of ties will work.  We use a bubble
                 * sort since the list is probably quite small.
                 */

                bubble( accset, nacc );

                dfaacc[newds].dfaacc_set = allocate_integer_array( nacc + 1 );

                /* Save the accepting set for later */
                for ( i = 1; i <= nacc; ++i )
                        {
                        dfaacc[newds].dfaacc_set[i] = accset[i];

                        if ( accset[i] <= num_rules )
                                /* Who knows, perhaps a REJECT can yield
                                 * this rule.
                                 */
                                rule_useful[accset[i]] = true;
                        }

                accsiz[newds] = nacc;
                }

        else
                {
                /* Find lowest numbered rule so the disambiguating rule
                 * will work.
                 */
                j = num_rules + 1;

                for ( i = 1; i <= nacc; ++i )
                        if ( accset[i] < j )
                                j = accset[i];

                dfaacc[newds].dfaacc_state = j;

                if ( j <= num_rules )
                        rule_useful[j] = true;
                }

        *newds_addr = newds;

        return 1;
        }


/* symfollowset - follow the symbol transitions one step
 *
 * synopsis
 *    numstates = symfollowset( int ds[current_max_dfa_size], int dsize,
 *                              int transsym, int nset[current_max_dfa_size] );
 */

int symfollowset( ds, dsize, transsym, nset )
int ds[], dsize, transsym, nset[];
        {
        int ns, tsp, sym, i, j, lenccl, ch, numstates, ccllist;

        numstates = 0;

        for ( i = 1; i <= dsize; ++i )
                { /* for each nfa state ns in the state set of ds */
                ns = ds[i];
                sym = transchar[ns];
                tsp = trans1[ns];

                if ( sym < 0 )
                        { /* it's a character class */
                        sym = -sym;
                        ccllist = cclmap[sym];
                        lenccl = ccllen[sym];

                        if ( cclng[sym] )
                                {
                                for ( j = 0; j < lenccl; ++j )
                                        {
                                        /* Loop through negated character
                                         * class.
                                         */
                                        ch = ccltbl[ccllist + j];

                                        if ( ch == 0 )
                                                ch = NUL_ec;

                                        if ( ch > transsym )
                                                /* Transsym isn't in negated
                                                 * ccl.
                                                 */
                                                break;

                                        else if ( ch == transsym )
                                                /* next 2 */ goto bottom;
                                        }

                                /* Didn't find transsym in ccl. */
                                nset[++numstates] = tsp;
                                }

                        else
                                for ( j = 0; j < lenccl; ++j )
                                        {
                                        ch = ccltbl[ccllist + j];

                                        if ( ch == 0 )
                                                ch = NUL_ec;

                                        if ( ch > transsym )
                                                break;
                                        else if ( ch == transsym )
                                                {
                                                nset[++numstates] = tsp;
                                                break;
                                                }
                                        }
                        }

                else if ( sym >= 'A' && sym <= 'Z' && caseins )
                        flexfatal(
                        _( "consistency check failed in symfollowset" ) );

                else if ( sym == SYM_EPSILON )
                        { /* do nothing */
                        }

                else if ( ABS( ecgroup[sym] ) == transsym )
                        nset[++numstates] = tsp;

                bottom: ;
                }

        return numstates;
        }


/* sympartition - partition characters with same out-transitions
 *
 * synopsis
 *    sympartition( int ds[current_max_dfa_size], int numstates,
 *                      int symlist[numecs], int duplist[numecs] );
 */

void sympartition( ds, numstates, symlist, duplist )
int ds[], numstates;
int symlist[], duplist[];
        {
        int tch, i, j, k, ns, dupfwd[CSIZE + 1], lenccl, cclp, ich;

        /* Partitioning is done by creating equivalence classes for those
         * characters which have out-transitions from the given state.  Thus
         * we are really creating equivalence classes of equivalence classes.
         */

        for ( i = 1; i <= numecs; ++i )
                { /* initialize equivalence class list */
                duplist[i] = i - 1;
                dupfwd[i] = i + 1;
                }

        duplist[1] = NIL;
        dupfwd[numecs] = NIL;

        for ( i = 1; i <= numstates; ++i )
                {
                ns = ds[i];
                tch = transchar[ns];

                if ( tch != SYM_EPSILON )
                        {
                        if ( tch < -lastccl || tch >= csize )
                                {
                                flexfatal(
                _( "bad transition character detected in sympartition()" ) );
                                }

                        if ( tch >= 0 )
                                { /* character transition */
                                int ec = ecgroup[tch];

                                mkechar( ec, dupfwd, duplist );
                                symlist[ec] = 1;
                                }

                        else
                                { /* character class */
                                tch = -tch;

                                lenccl = ccllen[tch];
                                cclp = cclmap[tch];
                                mkeccl( ccltbl + cclp, lenccl, dupfwd,
                                        duplist, numecs, NUL_ec );

                                if ( cclng[tch] )
                                        {
                                        j = 0;

                                        for ( k = 0; k < lenccl; ++k )
                                                {
                                                ich = ccltbl[cclp + k];

                                                if ( ich == 0 )
                                                        ich = NUL_ec;

                                                for ( ++j; j < ich; ++j )
                                                        symlist[j] = 1;
                                                }

                                        for ( ++j; j <= numecs; ++j )
                                                symlist[j] = 1;
                                        }

                                else
                                        for ( k = 0; k < lenccl; ++k )
                                                {
                                                ich = ccltbl[cclp + k];

                                                if ( ich == 0 )
                                                        ich = NUL_ec;

                                                symlist[ich] = 1;
                                                }
                                }
                        }
                }
        }