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Diffstat (limited to 'dfa.c')
| -rw-r--r-- | dfa.c | 1099 |
1 files changed, 1099 insertions, 0 deletions
@@ -0,0 +1,1099 @@ +/* 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 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" +#include "tables.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) \ +do{ trans1[state] = trans1[state] - MARKER_DIFFERENCE;} while(0) + +#define IS_MARKED(state) (trans1[state] < 0) + +#define UNMARK_STATE(state) \ +do{ trans1[state] = trans1[state] + MARKER_DIFFERENCE;} while(0) + +#define CHECK_ACCEPT(state) \ +do{ \ +nfaccnum = accptnum[state]; \ +if ( nfaccnum != NIL ) \ +accset[++nacc] = nfaccnum; \ +}while(0) + +#define DO_REALLOCATION() \ +do { \ +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 ); \ +}while(0) \ + +#define PUT_ON_STACK(state) \ +do { \ +if ( ++stkend >= current_max_dfa_size ) \ +DO_REALLOCATION(); \ +stk[stkend] = state; \ +MARK_STATE(state); \ +}while(0) + +#define ADD_STATE(state) \ +do { \ +if ( ++numstates >= current_max_dfa_size ) \ +DO_REALLOCATION(); \ +t[numstates] = state; \ +hashval += state; \ +}while(0) + +#define STACK_STATE(state) \ +do { \ +PUT_ON_STACK(state); \ +CHECK_ACCEPT(state); \ +if ( nfaccnum != NIL || transchar[state] != SYM_EPSILON ) \ +ADD_STATE(state); \ +}while(0) + + + 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=0; /* 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; + + struct yytbl_data *yynxt_tbl = 0; + flex_int32_t *yynxt_data = 0, yynxt_curr = 0; + + /* 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 needs to be large enough to hold all of the rules present + * in the input, *plus* their YY_TRAILING_HEAD_MASK variants. + */ + accset = allocate_integer_array ((num_rules + 1) * 2); + 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; + + /* Begin generating yy_nxt[][] + * This spans the entire LONG function. + * This table is tricky because we don't know how big it will be. + * So we'll have to realloc() on the way... + * we'll wait until we can calculate yynxt_tbl->td_hilen. + */ + yynxt_tbl = + (struct yytbl_data *) calloc (1, + sizeof (struct + yytbl_data)); + yytbl_data_init (yynxt_tbl, YYTD_ID_NXT); + yynxt_tbl->td_hilen = 1; + yynxt_tbl->td_lolen = num_full_table_rows; + yynxt_tbl->td_data = yynxt_data = + (flex_int32_t *) calloc (yynxt_tbl->td_lolen * + yynxt_tbl->td_hilen, + sizeof (flex_int32_t)); + yynxt_curr = 0; + + buf_prints (&yydmap_buf, + "\t{YYTD_ID_NXT, (void**)&yy_nxt, sizeof(%s)},\n", + long_align ? "flex_int32_t" : "flex_int16_t"); + + /* Unless -Ca, declare it "short" because it's a real + * long-shot that that won't be large enough. + */ + if (gentables) + out_str_dec + ("static yyconst %s yy_nxt[][%d] =\n {\n", + long_align ? "flex_int32_t" : "flex_int16_t", + num_full_table_rows); + else { + out_dec ("#undef YY_NXT_LOLEN\n#define YY_NXT_LOLEN (%d)\n", num_full_table_rows); + out_str ("static yyconst %s *yy_nxt =0;\n", + long_align ? "flex_int32_t" : "flex_int16_t"); + } + + + if (gentables) + outn (" {"); + + /* Generate 0 entries for state #0. */ + for (i = 0; i < num_full_table_rows; ++i) { + mk2data (0); + yynxt_data[yynxt_curr++] = 0; + } + + dataflush (); + if (gentables) + 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; + } + } + + + 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) { + + /* Each time we hit here, it's another td_hilen, so we realloc. */ + yynxt_tbl->td_hilen++; + yynxt_tbl->td_data = yynxt_data = + (flex_int32_t *) realloc (yynxt_data, + yynxt_tbl->td_hilen * + yynxt_tbl->td_lolen * + sizeof (flex_int32_t)); + + + if (gentables) + outn (" {"); + + /* Supply array's 0-element. */ + if (ds == end_of_buffer_state) { + mk2data (-end_of_buffer_state); + yynxt_data[yynxt_curr++] = + -end_of_buffer_state; + } + else { + mk2data (end_of_buffer_state); + yynxt_data[yynxt_curr++] = + 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); + yynxt_data[yynxt_curr++] = + state[i] ? state[i] : -ds; + } + + dataflush (); + if (gentables) + 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 (); + if (tablesext) { + yytbl_data_compress (yynxt_tbl); + if (yytbl_data_fwrite (&tableswr, yynxt_tbl) < 0) + flexerror (_ + ("Could not write yynxt_tbl[][]")); + } + if (yynxt_tbl) { + yytbl_data_destroy (yynxt_tbl); + yynxt_tbl = 0; + } + } + + 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 == 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; + } + } + } + } +} |