amiga-request@abcfd20.larc.nasa.gov (Amiga Sources/Binaries Moderator) (08/20/90)
Submitted-by: loftus@wpllabs.uucp (William P Loftus)
Posting-number: Volume 90, Issue 232
Archive-name: unix/flex-2.3/part05
#!/bin/sh
# This is a shell archive. Remove anything before this line, then unpack
# it by saving it into a file and typing "sh file". To overwrite existing
# files, type "sh file -c". You can also feed this as standard input via
# unshar, or by typing "sh <file", e.g.. If this archive is complete, you
# will see the following message at the end:
# "End of archive 5 (of 13)."
# Contents: dfa.c flex.Doc
# Wrapped by tadguy@abcfd20 on Sun Aug 19 18:41:44 1990
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
if test -f 'dfa.c' -a "${1}" != "-c" ; then
echo shar: Will not clobber existing file \"'dfa.c'\"
else
echo shar: Extracting \"'dfa.c'\" \(26919 characters\)
sed "s/^X//" >'dfa.c' <<'END_OF_FILE'
X/* dfa - DFA construction routines */
X
X/*-
X * Copyright (c) 1990 The Regents of the University of California.
X * All rights reserved.
X *
X * This code is derived from software contributed to Berkeley by
X * Vern Paxson.
X *
X * The United States Government has rights in this work pursuant
X * to contract no. DE-AC03-76SF00098 between the United States
X * Department of Energy and the University of California.
X *
X * Redistribution and use in source and binary forms are permitted provided
X * that: (1) source distributions retain this entire copyright notice and
X * comment, and (2) distributions including binaries display the following
X * acknowledgement: ``This product includes software developed by the
X * University of California, Berkeley and its contributors'' in the
X * documentation or other materials provided with the distribution and in
X * all advertising materials mentioning features or use of this software.
X * Neither the name of the University nor the names of its contributors may
X * be used to endorse or promote products derived from this software without
X * specific prior written permission.
X * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
X * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
X * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
X */
X
X#ifndef lint
Xstatic char rcsid[] =
X "@(#) $Header: /usr/fsys/odin/a/vern/flex/RCS/dfa.c,v 2.7 90/06/27 23:48:15 vern Exp $ (LBL)";
X#endif
X
X#include "flexdef.h"
X
X
X/* declare functions that have forward references */
X
Xvoid dump_associated_rules PROTO((FILE*, int));
Xvoid dump_transitions PROTO((FILE*, int[]));
Xvoid sympartition PROTO((int[], int, int[], int[]));
Xint symfollowset PROTO((int[], int, int, int[]));
X
X
X/* check_for_backtracking - check a DFA state for backtracking
X *
X * synopsis
X * int ds, state[numecs];
X * check_for_backtracking( ds, state );
X *
X * ds is the number of the state to check and state[] is its out-transitions,
X * indexed by equivalence class, and state_rules[] is the set of rules
X * associated with this state
X */
X
Xvoid check_for_backtracking( ds, state )
Xint ds;
Xint state[];
X
X {
X if ( (reject && ! dfaacc[ds].dfaacc_set) || ! dfaacc[ds].dfaacc_state )
X { /* state is non-accepting */
X ++num_backtracking;
X
X if ( backtrack_report )
X {
X fprintf( backtrack_file, "State #%d is non-accepting -\n", ds );
X
X /* identify the state */
X dump_associated_rules( backtrack_file, ds );
X
X /* now identify it further using the out- and jam-transitions */
X dump_transitions( backtrack_file, state );
X
X putc( '\n', backtrack_file );
X }
X }
X }
X
X
X/* check_trailing_context - check to see if NFA state set constitutes
X * "dangerous" trailing context
X *
X * synopsis
X * int nfa_states[num_states+1], num_states;
X * int accset[nacc+1], nacc;
X * check_trailing_context( nfa_states, num_states, accset, nacc );
X *
X * NOTES
X * Trailing context is "dangerous" if both the head and the trailing
X * part are of variable size \and/ there's a DFA state which contains
X * both an accepting state for the head part of the rule and NFA states
X * which occur after the beginning of the trailing context.
X * When such a rule is matched, it's impossible to tell if having been
X * in the DFA state indicates the beginning of the trailing context
X * or further-along scanning of the pattern. In these cases, a warning
X * message is issued.
X *
X * nfa_states[1 .. num_states] is the list of NFA states in the DFA.
X * accset[1 .. nacc] is the list of accepting numbers for the DFA state.
X */
X
Xvoid check_trailing_context( nfa_states, num_states, accset, nacc )
Xint *nfa_states, num_states;
Xint *accset;
Xregister int nacc;
X
X {
X register int i, j;
X
X for ( i = 1; i <= num_states; ++i )
X {
X int ns = nfa_states[i];
X register int type = state_type[ns];
X register int ar = assoc_rule[ns];
X
X if ( type == STATE_NORMAL || rule_type[ar] != RULE_VARIABLE )
X { /* do nothing */
X }
X
X else if ( type == STATE_TRAILING_CONTEXT )
X {
X /* potential trouble. Scan set of accepting numbers for
X * the one marking the end of the "head". We assume that
X * this looping will be fairly cheap since it's rare that
X * an accepting number set is large.
X */
X for ( j = 1; j <= nacc; ++j )
X if ( accset[j] & YY_TRAILING_HEAD_MASK )
X {
X fprintf( stderr,
X "%s: Dangerous trailing context in rule at line %d\n",
X program_name, rule_linenum[ar] );
X return;
X }
X }
X }
X }
X
X
X/* dump_associated_rules - list the rules associated with a DFA state
X *
X * synopisis
X * int ds;
X * FILE *file;
X * dump_associated_rules( file, ds );
X *
X * goes through the set of NFA states associated with the DFA and
X * extracts the first MAX_ASSOC_RULES unique rules, sorts them,
X * and writes a report to the given file
X */
X
Xvoid dump_associated_rules( file, ds )
XFILE *file;
Xint ds;
X
X {
X register int i, j;
X register int num_associated_rules = 0;
X int rule_set[MAX_ASSOC_RULES + 1];
X int *dset = dss[ds];
X int size = dfasiz[ds];
X
X for ( i = 1; i <= size; ++i )
X {
X register rule_num = rule_linenum[assoc_rule[dset[i]]];
X
X for ( j = 1; j <= num_associated_rules; ++j )
X if ( rule_num == rule_set[j] )
X break;
X
X if ( j > num_associated_rules )
X { /* new rule */
X if ( num_associated_rules < MAX_ASSOC_RULES )
X rule_set[++num_associated_rules] = rule_num;
X }
X }
X
X bubble( rule_set, num_associated_rules );
X
X fprintf( file, " associated rule line numbers:" );
X
X for ( i = 1; i <= num_associated_rules; ++i )
X {
X if ( i % 8 == 1 )
X putc( '\n', file );
X
X fprintf( file, "\t%d", rule_set[i] );
X }
X
X putc( '\n', file );
X }
X
X
X/* dump_transitions - list the transitions associated with a DFA state
X *
X * synopisis
X * int state[numecs];
X * FILE *file;
X * dump_transitions( file, state );
X *
X * goes through the set of out-transitions and lists them in human-readable
X * form (i.e., not as equivalence classes); also lists jam transitions
X * (i.e., all those which are not out-transitions, plus EOF). The dump
X * is done to the given file.
X */
X
Xvoid dump_transitions( file, state )
XFILE *file;
Xint state[];
X
X {
X register int i, ec;
X int out_char_set[CSIZE];
X
X for ( i = 0; i < csize; ++i )
X {
X ec = abs( ecgroup[i] );
X out_char_set[i] = state[ec];
X }
X
X fprintf( file, " out-transitions: " );
X
X list_character_set( file, out_char_set );
X
X /* now invert the members of the set to get the jam transitions */
X for ( i = 0; i < csize; ++i )
X out_char_set[i] = ! out_char_set[i];
X
X fprintf( file, "\n jam-transitions: EOF " );
X
X list_character_set( file, out_char_set );
X
X putc( '\n', file );
X }
X
X
X/* epsclosure - construct the epsilon closure of a set of ndfa states
X *
X * synopsis
X * int t[current_max_dfa_size], numstates, accset[num_rules + 1], nacc;
X * int hashval;
X * int *epsclosure();
X * t = epsclosure( t, &numstates, accset, &nacc, &hashval );
X *
X * NOTES
X * the epsilon closure is the set of all states reachable by an arbitrary
X * number of epsilon transitions which themselves do not have epsilon
X * transitions going out, unioned with the set of states which have non-null
X * accepting numbers. t is an array of size numstates of nfa state numbers.
X * Upon return, t holds the epsilon closure and numstates is updated. accset
X * holds a list of the accepting numbers, and the size of accset is given
X * by nacc. t may be subjected to reallocation if it is not large enough
X * to hold the epsilon closure.
X *
X * hashval is the hash value for the dfa corresponding to the state set
X */
X
Xint *epsclosure( t, ns_addr, accset, nacc_addr, hv_addr )
Xint *t, *ns_addr, accset[], *nacc_addr, *hv_addr;
X
X {
X register int stkpos, ns, tsp;
X int numstates = *ns_addr, nacc, hashval, transsym, nfaccnum;
X int stkend, nstate;
X static int did_stk_init = false, *stk;
X
X#define MARK_STATE(state) \
X trans1[state] = trans1[state] - MARKER_DIFFERENCE;
X
X#define IS_MARKED(state) (trans1[state] < 0)
X
X#define UNMARK_STATE(state) \
X trans1[state] = trans1[state] + MARKER_DIFFERENCE;
X
X#define CHECK_ACCEPT(state) \
X { \
X nfaccnum = accptnum[state]; \
X if ( nfaccnum != NIL ) \
X accset[++nacc] = nfaccnum; \
X }
X
X#define DO_REALLOCATION \
X { \
X current_max_dfa_size += MAX_DFA_SIZE_INCREMENT; \
X ++num_reallocs; \
X t = reallocate_integer_array( t, current_max_dfa_size ); \
X stk = reallocate_integer_array( stk, current_max_dfa_size ); \
X } \
X
X#define PUT_ON_STACK(state) \
X { \
X if ( ++stkend >= current_max_dfa_size ) \
X DO_REALLOCATION \
X stk[stkend] = state; \
X MARK_STATE(state) \
X }
X
X#define ADD_STATE(state) \
X { \
X if ( ++numstates >= current_max_dfa_size ) \
X DO_REALLOCATION \
X t[numstates] = state; \
X hashval = hashval + state; \
X }
X
X#define STACK_STATE(state) \
X { \
X PUT_ON_STACK(state) \
X CHECK_ACCEPT(state) \
X if ( nfaccnum != NIL || transchar[state] != SYM_EPSILON ) \
X ADD_STATE(state) \
X }
X
X if ( ! did_stk_init )
X {
X stk = allocate_integer_array( current_max_dfa_size );
X did_stk_init = true;
X }
X
X nacc = stkend = hashval = 0;
X
X for ( nstate = 1; nstate <= numstates; ++nstate )
X {
X ns = t[nstate];
X
X /* the state could be marked if we've already pushed it onto
X * the stack
X */
X if ( ! IS_MARKED(ns) )
X PUT_ON_STACK(ns)
X
X CHECK_ACCEPT(ns)
X hashval = hashval + ns;
X }
X
X for ( stkpos = 1; stkpos <= stkend; ++stkpos )
X {
X ns = stk[stkpos];
X transsym = transchar[ns];
X
X if ( transsym == SYM_EPSILON )
X {
X tsp = trans1[ns] + MARKER_DIFFERENCE;
X
X if ( tsp != NO_TRANSITION )
X {
X if ( ! IS_MARKED(tsp) )
X STACK_STATE(tsp)
X
X tsp = trans2[ns];
X
X if ( tsp != NO_TRANSITION )
X if ( ! IS_MARKED(tsp) )
X STACK_STATE(tsp)
X }
X }
X }
X
X /* clear out "visit" markers */
X
X for ( stkpos = 1; stkpos <= stkend; ++stkpos )
X {
X if ( IS_MARKED(stk[stkpos]) )
X {
X UNMARK_STATE(stk[stkpos])
X }
X else
X flexfatal( "consistency check failed in epsclosure()" );
X }
X
X *ns_addr = numstates;
X *hv_addr = hashval;
X *nacc_addr = nacc;
X
X return ( t );
X }
X
X
X/* increase_max_dfas - increase the maximum number of DFAs */
X
Xvoid increase_max_dfas()
X
X {
X current_max_dfas += MAX_DFAS_INCREMENT;
X
X ++num_reallocs;
X
X base = reallocate_integer_array( base, current_max_dfas );
X def = reallocate_integer_array( def, current_max_dfas );
X dfasiz = reallocate_integer_array( dfasiz, current_max_dfas );
X accsiz = reallocate_integer_array( accsiz, current_max_dfas );
X dhash = reallocate_integer_array( dhash, current_max_dfas );
X dss = reallocate_int_ptr_array( dss, current_max_dfas );
X dfaacc = reallocate_dfaacc_union( dfaacc, current_max_dfas );
X
X if ( nultrans )
X nultrans = reallocate_integer_array( nultrans, current_max_dfas );
X }
X
X
X/* ntod - convert an ndfa to a dfa
X *
X * synopsis
X * ntod();
X *
X * creates the dfa corresponding to the ndfa we've constructed. the
X * dfa starts out in state #1.
X */
X
Xvoid ntod()
X
X {
X int *accset, ds, nacc, newds;
X int sym, hashval, numstates, dsize;
X int num_full_table_rows; /* used only for -f */
X int *nset, *dset;
X int targptr, totaltrans, i, comstate, comfreq, targ;
X int *epsclosure(), snstods(), symlist[CSIZE + 1];
X int num_start_states;
X int todo_head, todo_next;
X
X /* note that the following are indexed by *equivalence classes*
X * and not by characters. Since equivalence classes are indexed
X * beginning with 1, even if the scanner accepts NUL's, this
X * means that (since every character is potentially in its own
X * equivalence class) these arrays must have room for indices
X * from 1 to CSIZE, so their size must be CSIZE + 1.
X */
X int duplist[CSIZE + 1], state[CSIZE + 1];
X int targfreq[CSIZE + 1], targstate[CSIZE + 1];
X
X /* this is so find_table_space(...) will know where to start looking in
X * chk/nxt for unused records for space to put in the state
X */
X if ( fullspd )
X firstfree = 0;
X
X accset = allocate_integer_array( num_rules + 1 );
X nset = allocate_integer_array( current_max_dfa_size );
X
X /* the "todo" queue is represented by the head, which is the DFA
X * state currently being processed, and the "next", which is the
X * next DFA state number available (not in use). We depend on the
X * fact that snstods() returns DFA's \in increasing order/, and thus
X * need only know the bounds of the dfas to be processed.
X */
X todo_head = todo_next = 0;
X
X for ( i = 0; i <= csize; ++i )
X {
X duplist[i] = NIL;
X symlist[i] = false;
X }
X
X for ( i = 0; i <= num_rules; ++i )
X accset[i] = NIL;
X
X if ( trace )
X {
X dumpnfa( scset[1] );
X fputs( "\n\nDFA Dump:\n\n", stderr );
X }
X
X inittbl();
X
X /* check to see whether we should build a separate table for transitions
X * on NUL characters. We don't do this for full-speed (-F) scanners,
X * since for them we don't have a simple state number lying around with
X * which to index the table. We also don't bother doing it for scanners
X * unless (1) NUL is in its own equivalence class (indicated by a
X * positive value of ecgroup[NUL]), (2) NUL's equilvalence class is
X * the last equivalence class, and (3) the number of equivalence classes
X * is the same as the number of characters. This latter case comes about
X * when useecs is false or when its true but every character still
X * manages to land in its own class (unlikely, but it's cheap to check
X * for). If all these things are true then the character code needed
X * to represent NUL's equivalence class for indexing the tables is
X * going to take one more bit than the number of characters, and therefore
X * we won't be assured of being able to fit it into a YY_CHAR variable.
X * This rules out storing the transitions in a compressed table, since
X * the code for interpreting them uses a YY_CHAR variable (perhaps it
X * should just use an integer, though; this is worth pondering ... ###).
X *
X * Finally, for full tables, we want the number of entries in the
X * table to be a power of two so the array references go fast (it
X * will just take a shift to compute the major index). If encoding
X * NUL's transitions in the table will spoil this, we give it its
X * own table (note that this will be the case if we're not using
X * equivalence classes).
X */
X
X /* note that the test for ecgroup[0] == numecs below accomplishes
X * both (1) and (2) above
X */
X if ( ! fullspd && ecgroup[0] == numecs )
X { /* NUL is alone in its equivalence class, which is the last one */
X int use_NUL_table = (numecs == csize);
X
X if ( fulltbl && ! use_NUL_table )
X { /* we still may want to use the table if numecs is a power of 2 */
X int power_of_two;
X
X for ( power_of_two = 1; power_of_two <= csize; power_of_two *= 2 )
X if ( numecs == power_of_two )
X {
X use_NUL_table = true;
X break;
X }
X }
X
X if ( use_NUL_table )
X nultrans = allocate_integer_array( current_max_dfas );
X /* from now on, nultrans != nil indicates that we're
X * saving null transitions for later, separate encoding
X */
X }
X
X
X if ( fullspd )
X {
X for ( i = 0; i <= numecs; ++i )
X state[i] = 0;
X place_state( state, 0, 0 );
X }
X
X else if ( fulltbl )
X {
X if ( nultrans )
X /* we won't be including NUL's transitions in the table,
X * so build it for entries from 0 .. numecs - 1
X */
X num_full_table_rows = numecs;
X
X else
X /* take into account the fact that we'll be including
X * the NUL entries in the transition table. Build it
X * from 0 .. numecs.
X */
X num_full_table_rows = numecs + 1;
X
X /* declare it "short" because it's a real long-shot that that
X * won't be large enough.
X */
X printf( "static short int yy_nxt[][%d] =\n {\n",
X /* '}' so vi doesn't get too confused */
X num_full_table_rows );
X
X /* generate 0 entries for state #0 */
X for ( i = 0; i < num_full_table_rows; ++i )
X mk2data( 0 );
X
X /* force ',' and dataflush() next call to mk2data */
X datapos = NUMDATAITEMS;
X
X /* force extra blank line next dataflush() */
X dataline = NUMDATALINES;
X }
X
X /* create the first states */
X
X num_start_states = lastsc * 2;
X
X for ( i = 1; i <= num_start_states; ++i )
X {
X numstates = 1;
X
X /* for each start condition, make one state for the case when
X * we're at the beginning of the line (the '%' operator) and
X * one for the case when we're not
X */
X if ( i % 2 == 1 )
X nset[numstates] = scset[(i / 2) + 1];
X else
X nset[numstates] = mkbranch( scbol[i / 2], scset[i / 2] );
X
X nset = epsclosure( nset, &numstates, accset, &nacc, &hashval );
X
X if ( snstods( nset, numstates, accset, nacc, hashval, &ds ) )
X {
X numas += nacc;
X totnst += numstates;
X ++todo_next;
X
X if ( variable_trailing_context_rules && nacc > 0 )
X check_trailing_context( nset, numstates, accset, nacc );
X }
X }
X
X if ( ! fullspd )
X {
X if ( ! snstods( nset, 0, accset, 0, 0, &end_of_buffer_state ) )
X flexfatal( "could not create unique end-of-buffer state" );
X
X ++numas;
X ++num_start_states;
X ++todo_next;
X }
X
X while ( todo_head < todo_next )
X {
X targptr = 0;
X totaltrans = 0;
X
X for ( i = 1; i <= numecs; ++i )
X state[i] = 0;
X
X ds = ++todo_head;
X
X dset = dss[ds];
X dsize = dfasiz[ds];
X
X if ( trace )
X fprintf( stderr, "state # %d:\n", ds );
X
X sympartition( dset, dsize, symlist, duplist );
X
X for ( sym = 1; sym <= numecs; ++sym )
X {
X if ( symlist[sym] )
X {
X symlist[sym] = 0;
X
X if ( duplist[sym] == NIL )
X { /* symbol has unique out-transitions */
X numstates = symfollowset( dset, dsize, sym, nset );
X nset = epsclosure( nset, &numstates, accset,
X &nacc, &hashval );
X
X if ( snstods( nset, numstates, accset,
X nacc, hashval, &newds ) )
X {
X totnst = totnst + numstates;
X ++todo_next;
X numas += nacc;
X
X if ( variable_trailing_context_rules && nacc > 0 )
X check_trailing_context( nset, numstates,
X accset, nacc );
X }
X
X state[sym] = newds;
X
X if ( trace )
X fprintf( stderr, "\t%d\t%d\n", sym, newds );
X
X targfreq[++targptr] = 1;
X targstate[targptr] = newds;
X ++numuniq;
X }
X
X else
X {
X /* sym's equivalence class has the same transitions
X * as duplist(sym)'s equivalence class
X */
X targ = state[duplist[sym]];
X state[sym] = targ;
X
X if ( trace )
X fprintf( stderr, "\t%d\t%d\n", sym, targ );
X
X /* update frequency count for destination state */
X
X i = 0;
X while ( targstate[++i] != targ )
X ;
X
X ++targfreq[i];
X ++numdup;
X }
X
X ++totaltrans;
X duplist[sym] = NIL;
X }
X }
X
X numsnpairs = numsnpairs + totaltrans;
X
X if ( caseins && ! useecs )
X {
X register int j;
X
X for ( i = 'A', j = 'a'; i <= 'Z'; ++i, ++j )
X state[i] = state[j];
X }
X
X if ( ds > num_start_states )
X check_for_backtracking( ds, state );
X
X if ( nultrans )
X {
X nultrans[ds] = state[NUL_ec];
X state[NUL_ec] = 0; /* remove transition */
X }
X
X if ( fulltbl )
X {
X /* supply array's 0-element */
X if ( ds == end_of_buffer_state )
X mk2data( -end_of_buffer_state );
X else
X mk2data( end_of_buffer_state );
X
X for ( i = 1; i < num_full_table_rows; ++i )
X /* jams are marked by negative of state number */
X mk2data( state[i] ? state[i] : -ds );
X
X /* force ',' and dataflush() next call to mk2data */
X datapos = NUMDATAITEMS;
X
X /* force extra blank line next dataflush() */
X dataline = NUMDATALINES;
X }
X
X else if ( fullspd )
X place_state( state, ds, totaltrans );
X
X else if ( ds == end_of_buffer_state )
X /* special case this state to make sure it does what it's
X * supposed to, i.e., jam on end-of-buffer
X */
X stack1( ds, 0, 0, JAMSTATE );
X
X else /* normal, compressed state */
X {
X /* determine which destination state is the most common, and
X * how many transitions to it there are
X */
X
X comfreq = 0;
X comstate = 0;
X
X for ( i = 1; i <= targptr; ++i )
X if ( targfreq[i] > comfreq )
X {
X comfreq = targfreq[i];
X comstate = targstate[i];
X }
X
X bldtbl( state, ds, totaltrans, comstate, comfreq );
X }
X }
X
X if ( fulltbl )
X dataend();
X
X else if ( ! fullspd )
X {
X cmptmps(); /* create compressed template entries */
X
X /* create tables for all the states with only one out-transition */
X while ( onesp > 0 )
X {
X mk1tbl( onestate[onesp], onesym[onesp], onenext[onesp],
X onedef[onesp] );
X --onesp;
X }
X
X mkdeftbl();
X }
X }
X
X
X/* snstods - converts a set of ndfa states into a dfa state
X *
X * synopsis
X * int sns[numstates], numstates, newds, accset[num_rules + 1], nacc, hashval;
X * int snstods();
X * is_new_state = snstods( sns, numstates, accset, nacc, hashval, &newds );
X *
X * on return, the dfa state number is in newds.
X */
X
Xint snstods( sns, numstates, accset, nacc, hashval, newds_addr )
Xint sns[], numstates, accset[], nacc, hashval, *newds_addr;
X
X {
X int didsort = 0;
X register int i, j;
X int newds, *oldsns;
X
X for ( i = 1; i <= lastdfa; ++i )
X if ( hashval == dhash[i] )
X {
X if ( numstates == dfasiz[i] )
X {
X oldsns = dss[i];
X
X if ( ! didsort )
X {
X /* we sort the states in sns so we can compare it to
X * oldsns quickly. we use bubble because there probably
X * aren't very many states
X */
X bubble( sns, numstates );
X didsort = 1;
X }
X
X for ( j = 1; j <= numstates; ++j )
X if ( sns[j] != oldsns[j] )
X break;
X
X if ( j > numstates )
X {
X ++dfaeql;
X *newds_addr = i;
X return ( 0 );
X }
X
X ++hshcol;
X }
X
X else
X ++hshsave;
X }
X
X /* make a new dfa */
X
X if ( ++lastdfa >= current_max_dfas )
X increase_max_dfas();
X
X newds = lastdfa;
X
X dss[newds] = (int *) malloc( (unsigned) ((numstates + 1) * sizeof( int )) );
X
X if ( ! dss[newds] )
X flexfatal( "dynamic memory failure in snstods()" );
X
X /* if we haven't already sorted the states in sns, we do so now, so that
X * future comparisons with it can be made quickly
X */
X
X if ( ! didsort )
X bubble( sns, numstates );
X
X for ( i = 1; i <= numstates; ++i )
X dss[newds][i] = sns[i];
X
X dfasiz[newds] = numstates;
X dhash[newds] = hashval;
X
X if ( nacc == 0 )
X {
X if ( reject )
X dfaacc[newds].dfaacc_set = (int *) 0;
X else
X dfaacc[newds].dfaacc_state = 0;
X
X accsiz[newds] = 0;
X }
X
X else if ( reject )
X {
X /* we sort the accepting set in increasing order so the disambiguating
X * rule that the first rule listed is considered match in the event of
X * ties will work. We use a bubble sort since the list is probably
X * quite small.
X */
X
X bubble( accset, nacc );
X
X dfaacc[newds].dfaacc_set =
X (int *) malloc( (unsigned) ((nacc + 1) * sizeof( int )) );
X
X if ( ! dfaacc[newds].dfaacc_set )
X flexfatal( "dynamic memory failure in snstods()" );
X
X /* save the accepting set for later */
X for ( i = 1; i <= nacc; ++i )
X dfaacc[newds].dfaacc_set[i] = accset[i];
X
X accsiz[newds] = nacc;
X }
X
X else
X { /* find lowest numbered rule so the disambiguating rule will work */
X j = num_rules + 1;
X
X for ( i = 1; i <= nacc; ++i )
X if ( accset[i] < j )
X j = accset[i];
X
X dfaacc[newds].dfaacc_state = j;
X }
X
X *newds_addr = newds;
X
X return ( 1 );
X }
X
X
X/* symfollowset - follow the symbol transitions one step
X *
X * synopsis
X * int ds[current_max_dfa_size], dsize, transsym;
X * int nset[current_max_dfa_size], numstates;
X * numstates = symfollowset( ds, dsize, transsym, nset );
X */
X
Xint symfollowset( ds, dsize, transsym, nset )
Xint ds[], dsize, transsym, nset[];
X
X {
X int ns, tsp, sym, i, j, lenccl, ch, numstates;
X int ccllist;
X
X numstates = 0;
X
X for ( i = 1; i <= dsize; ++i )
X { /* for each nfa state ns in the state set of ds */
X ns = ds[i];
X sym = transchar[ns];
X tsp = trans1[ns];
X
X if ( sym < 0 )
X { /* it's a character class */
X sym = -sym;
X ccllist = cclmap[sym];
X lenccl = ccllen[sym];
X
X if ( cclng[sym] )
X {
X for ( j = 0; j < lenccl; ++j )
X { /* loop through negated character class */
X ch = ccltbl[ccllist + j];
X
X if ( ch == 0 )
X ch = NUL_ec;
X
X if ( ch > transsym )
X break; /* transsym isn't in negated ccl */
X
X else if ( ch == transsym )
X /* next 2 */ goto bottom;
X }
X
X /* didn't find transsym in ccl */
X nset[++numstates] = tsp;
X }
X
X else
X for ( j = 0; j < lenccl; ++j )
X {
X ch = ccltbl[ccllist + j];
X
X if ( ch == 0 )
X ch = NUL_ec;
X
X if ( ch > transsym )
X break;
X
X else if ( ch == transsym )
X {
X nset[++numstates] = tsp;
X break;
X }
X }
X }
X
X else if ( sym >= 'A' && sym <= 'Z' && caseins )
X flexfatal( "consistency check failed in symfollowset" );
X
X else if ( sym == SYM_EPSILON )
X { /* do nothing */
X }
X
X else if ( abs( ecgroup[sym] ) == transsym )
X nset[++numstates] = tsp;
X
Xbottom:
X ;
X }
X
X return ( numstates );
X }
X
X
X/* sympartition - partition characters with same out-transitions
X *
X * synopsis
X * integer ds[current_max_dfa_size], numstates, duplist[numecs];
X * symlist[numecs];
X * sympartition( ds, numstates, symlist, duplist );
X */
X
Xvoid sympartition( ds, numstates, symlist, duplist )
Xint ds[], numstates, duplist[];
Xint symlist[];
X
X {
X int tch, i, j, k, ns, dupfwd[CSIZE + 1], lenccl, cclp, ich;
X
X /* partitioning is done by creating equivalence classes for those
X * characters which have out-transitions from the given state. Thus
X * we are really creating equivalence classes of equivalence classes.
X */
X
X for ( i = 1; i <= numecs; ++i )
X { /* initialize equivalence class list */
X duplist[i] = i - 1;
X dupfwd[i] = i + 1;
X }
X
X duplist[1] = NIL;
X dupfwd[numecs] = NIL;
X
X for ( i = 1; i <= numstates; ++i )
X {
X ns = ds[i];
X tch = transchar[ns];
X
X if ( tch != SYM_EPSILON )
X {
X if ( tch < -lastccl || tch > csize )
X {
X if ( tch > csize && tch <= CSIZE )
X flexerror( "scanner requires -8 flag" );
X
X else
X flexfatal(
X "bad transition character detected in sympartition()" );
X }
X
X if ( tch >= 0 )
X { /* character transition */
X /* abs() needed for fake %t ec's */
X int ec = abs( ecgroup[tch] );
X
X mkechar( ec, dupfwd, duplist );
X symlist[ec] = 1;
X }
X
X else
X { /* character class */
X tch = -tch;
X
X lenccl = ccllen[tch];
X cclp = cclmap[tch];
X mkeccl( ccltbl + cclp, lenccl, dupfwd, duplist, numecs,
X NUL_ec );
X
X if ( cclng[tch] )
X {
X j = 0;
X
X for ( k = 0; k < lenccl; ++k )
X {
X ich = ccltbl[cclp + k];
X
X if ( ich == 0 )
X ich = NUL_ec;
X
X for ( ++j; j < ich; ++j )
X symlist[j] = 1;
X }
X
X for ( ++j; j <= numecs; ++j )
X symlist[j] = 1;
X }
X
X else
X for ( k = 0; k < lenccl; ++k )
X {
X ich = ccltbl[cclp + k];
X
X if ( ich == 0 )
X ich = NUL_ec;
X
X symlist[ich] = 1;
X }
X }
X }
X }
X }
END_OF_FILE
if test 26919 -ne `wc -c <'dfa.c'`; then
echo shar: \"'dfa.c'\" unpacked with wrong size!
fi
# end of 'dfa.c'
fi
if test -f 'flex.Doc' -a "${1}" != "-c" ; then
echo shar: Will not clobber existing file \"'flex.Doc'\"
else
echo shar: Extracting \"'flex.Doc'\" \(25372 characters\)
sed "s/^X//" >'flex.Doc' <<'END_OF_FILE'
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
XNAME
X flex - fast lexical analyzer generator
X
XSYNOPSIS
X flex [-bcdfinpstvFILT8 -C[efmF] -Sskeleton] [filename ...]
X
XDESCRIPTION
X flex is a tool for generating scanners: programs which
X recognized lexical patterns in text. flex reads the given
X input files, or its standard input if no file names are
X given, for a description of a scanner to generate. The
X description is in the form of pairs of regular expressions
X and C code, called rules. flex generates as output a C
X source file, lex.yy.c, which defines a routine yylex(). This
X file is compiled and linked with the -lfl library to produce
X an executable. When the executable is run, it analyzes its
X input for occurrences of the regular expressions. Whenever
X it finds one, it executes the corresponding C code.
X
X For full documentation, see flexdoc(1). This manual entry is
X intended for use as a quick reference.
X
XOPTIONS
X flex has the following options:
X
X -b Generate backtracking information to lex.backtrack.
X This is a list of scanner states which require back-
X tracking and the input characters on which they do so.
X By adding rules one can remove backtracking states. If
X all backtracking states are eliminated and -f or -F is
X used, the generated scanner will run faster.
X
X -c is a do-nothing, deprecated option included for POSIX
X compliance.
X
X NOTE: in previous releases of flex -c specified table-
X compression options. This functionality is now given
X by the -C flag. To ease the the impact of this change,
X when flex encounters -c, it currently issues a warning
X message and assumes that -C was desired instead. In
X the future this "promotion" of -c to -C will go away in
X the name of full POSIX compliance (unless the POSIX
X meaning is removed first).
X
X -d makes the generated scanner run in debug mode. When-
X ever a pattern is recognized and the global
X yy_flex_debug is non-zero (which is the default), the
X scanner will write to stderr a line of the form:
X
X --accepting rule at line 53 ("the matched text")
X
X The line number refers to the location of the rule in
X
X
X
XVersion 2.3 Last change: 26 May 1990 1
X
X
X
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
X the file defining the scanner (i.e., the file that was
X fed to flex). Messages are also generated when the
X scanner backtracks, accepts the default rule, reaches
X the end of its input buffer (or encounters a NUL; the
X two look the same as far as the scanner's concerned),
X or reaches an end-of-file.
X
X -f specifies (take your pick) full table or fast scanner.
X No table compression is done. The result is large but
X fast. This option is equivalent to -Cf (see below).
X
X -i instructs flex to generate a case-insensitive scanner.
X The case of letters given in the flex input patterns
X will be ignored, and tokens in the input will be
X matched regardless of case. The matched text given in
X yytext will have the preserved case (i.e., it will not
X be folded).
X
X -n is another do-nothing, deprecated option included only
X for POSIX compliance.
X
X -p generates a performance report to stderr. The report
X consists of comments regarding features of the flex
X input file which will cause a loss of performance in
X the resulting scanner.
X
X -s causes the default rule (that unmatched scanner input
X is echoed to stdout) to be suppressed. If the scanner
X encounters input that does not match any of its rules,
X it aborts with an error.
X
X -t instructs flex to write the scanner it generates to
X standard output instead of lex.yy.c.
X
X -v specifies that flex should write to stderr a summary of
X statistics regarding the scanner it generates.
X
X -F specifies that the fast scanner table representation
X should be used. This representation is about as fast
X as the full table representation (-f), and for some
X sets of patterns will be considerably smaller (and for
X others, larger). See flexdoc(1) for details.
X
X This option is equivalent to -CF (see below).
X
X -I instructs flex to generate an interactive scanner, that
X is, a scanner which stops immediately rather than look-
X ing ahead if it knows that the currently scanned text
X cannot be part of a longer rule's match. Again, see
X flexdoc(1) for details.
X
X Note, -I cannot be used in conjunction with full or
X
X
X
XVersion 2.3 Last change: 26 May 1990 2
X
X
X
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
X fast tables, i.e., the -f, -F, -Cf, or -CF flags.
X
X -L instructs flex not to generate #line directives in
X lex.yy.c. The default is to generate such directives so
X error messages in the actions will be correctly located
X with respect to the original flex input file, and not
X to the fairly meaningless line numbers of lex.yy.c.
X
X -T makes flex run in trace mode. It will generate a lot
X of messages to stdout concerning the form of the input
X and the resultant non-deterministic and deterministic
X finite automata. This option is mostly for use in
X maintaining flex.
X
X -8 instructs flex to generate an 8-bit scanner. On some
X sites, this is the default. On others, the default is
X 7-bit characters. To see which is the case, check the
X verbose (-v) output for "equivalence classes created".
X If the denominator of the number shown is 128, then by
X default flex is generating 7-bit characters. If it is
X 256, then the default is 8-bit characters.
X
X -C[efmF]
X controls the degree of table compression.
X
X -Ce directs flex to construct equivalence classes,
X i.e., sets of characters which have identical lexical
X properties. Equivalence classes usually give dramatic
X reductions in the final table/object file sizes (typi-
X cally a factor of 2-5) and are pretty cheap
X performance-wise (one array look-up per character
X scanned).
X
X -Cf specifies that the full scanner tables should be
X generated - flex should not compress the tables by tak-
X ing advantages of similar transition functions for dif-
X ferent states.
X
X -CF specifies that the alternate fast scanner represen-
X tation (described in flexdoc(1)) should be used.
X
X -Cm directs flex to construct meta-equivalence classes,
X which are sets of equivalence classes (or characters,
X if equivalence classes are not being used) that are
X commonly used together. Meta-equivalence classes are
X often a big win when using compressed tables, but they
X have a moderate performance impact (one or two "if"
X tests and one array look-up per character scanned).
X
X A lone -C specifies that the scanner tables should be
X compressed but neither equivalence classes nor meta-
X equivalence classes should be used.
X
X
X
XVersion 2.3 Last change: 26 May 1990 3
X
X
X
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
X The options -Cf or -CF and -Cm do not make sense
X together - there is no opportunity for meta-equivalence
X classes if the table is not being compressed. Other-
X wise the options may be freely mixed.
X
X The default setting is -Cem, which specifies that flex
X should generate equivalence classes and meta-
X equivalence classes. This setting provides the highest
X degree of table compression. You can trade off
X faster-executing scanners at the cost of larger tables
X with the following generally being true:
X
X slowest & smallest
X -Cem
X -Cm
X -Ce
X -C
X -C{f,F}e
X -C{f,F}
X fastest & largest
X
X
X -C options are not cumulative; whenever the flag is
X encountered, the previous -C settings are forgotten.
X
X -Sskeleton_file
X overrides the default skeleton file from which flex
X constructs its scanners. You'll never need this option
X unless you are doing flex maintenance or development.
X
XSUMMARY OF FLEX REGULAR EXPRESSIONS
X The patterns in the input are written using an extended set
X of regular expressions. These are:
X
X x match the character 'x'
X . any character except newline
X [xyz] a "character class"; in this case, the pattern
X matches either an 'x', a 'y', or a 'z'
X [abj-oZ] a "character class" with a range in it; matches
X an 'a', a 'b', any letter from 'j' through 'o',
X or a 'Z'
X [^A-Z] a "negated character class", i.e., any character
X but those in the class. In this case, any
X character EXCEPT an uppercase letter.
X [^A-Z\n] any character EXCEPT an uppercase letter or
X a newline
X r* zero or more r's, where r is any regular expression
X r+ one or more r's
X r? zero or one r's (that is, "an optional r")
X r{2,5} anywhere from two to five r's
X r{2,} two or more r's
X r{4} exactly 4 r's
X
X
X
XVersion 2.3 Last change: 26 May 1990 4
X
X
X
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
X {name} the expansion of the "name" definition
X (see above)
X "[xyz]\"foo"
X the literal string: [xyz]"foo
X \X if X is an 'a', 'b', 'f', 'n', 'r', 't', or 'v',
X then the ANSI-C interpretation of \x.
X Otherwise, a literal 'X' (used to escape
X operators such as '*')
X \123 the character with octal value 123
X \x2a the character with hexadecimal value 2a
X (r) match an r; parentheses are used to override
X precedence (see below)
X
X
X rs the regular expression r followed by the
X regular expression s; called "concatenation"
X
X
X r|s either an r or an s
X
X
X r/s an r but only if it is followed by an s. The
X s is not part of the matched text. This type
X of pattern is called as "trailing context".
X ^r an r, but only at the beginning of a line
X r$ an r, but only at the end of a line. Equivalent
X to "r/\n".
X
X
X <s>r an r, but only in start condition s (see
X below for discussion of start conditions)
X <s1,s2,s3>r
X same, but in any of start conditions s1,
X s2, or s3
X
X
X <<EOF>> an end-of-file
X <s1,s2><<EOF>>
X an end-of-file when in start condition s1 or s2
X
X The regular expressions listed above are grouped according
X to precedence, from highest precedence at the top to lowest
X at the bottom. Those grouped together have equal pre-
X cedence.
X
X Some notes on patterns:
X
X - Negated character classes match newlines unless "\n"
X (or an equivalent escape sequence) is one of the char-
X acters explicitly present in the negated character
X class (e.g., "[^A-Z\n]").
X
X
X
X
XVersion 2.3 Last change: 26 May 1990 5
X
X
X
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
X - A rule can have at most one instance of trailing con-
X text (the '/' operator or the '$' operator). The start
X condition, '^', and "<<EOF>>" patterns can only occur
X at the beginning of a pattern, and, as well as with '/'
X and '$', cannot be grouped inside parentheses. The
X following are all illegal:
X
X foo/bar$
X foo|(bar$)
X foo|^bar
X <sc1>foo<sc2>bar
X
X
XSUMMARY OF SPECIAL ACTIONS
X In addition to arbitrary C code, the following can appear in
X actions:
X
X - ECHO copies yytext to the scanner's output.
X
X - BEGIN followed by the name of a start condition places
X the scanner in the corresponding start condition.
X
X - REJECT directs the scanner to proceed on to the "second
X best" rule which matched the input (or a prefix of the
X input). yytext and yyleng are set up appropriately.
X Note that REJECT is a particularly expensive feature in
X terms scanner performance; if it is used in any of the
X scanner's actions it will slow down all of the
X scanner's matching. Furthermore, REJECT cannot be used
X with the -f or -F options.
X
X Note also that unlike the other special actions, REJECT
X is a branch; code immediately following it in the
X action will not be executed.
X
X - yymore() tells the scanner that the next time it
X matches a rule, the corresponding token should be
X appended onto the current value of yytext rather than
X replacing it.
X
X - yyless(n) returns all but the first n characters of the
X current token back to the input stream, where they will
X be rescanned when the scanner looks for the next match.
X yytext and yyleng are adjusted appropriately (e.g.,
X yyleng will now be equal to n ).
X
X - unput(c) puts the character c back onto the input
X stream. It will be the next character scanned.
X
X - input() reads the next character from the input stream
X (this routine is called yyinput() if the scanner is
X compiled using C++).
X
X
X
XVersion 2.3 Last change: 26 May 1990 6
X
X
X
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
X - yyterminate() can be used in lieu of a return statement
X in an action. It terminates the scanner and returns a
X 0 to the scanner's caller, indicating "all done".
X
X By default, yyterminate() is also called when an end-
X of-file is encountered. It is a macro and may be rede-
X fined.
X
X - YY_NEW_FILE is an action available only in <<EOF>>
X rules. It means "Okay, I've set up a new input file,
X continue scanning".
X
X - yy_create_buffer( file, size ) takes a FILE pointer and
X an integer size. It returns a YY_BUFFER_STATE handle to
X a new input buffer large enough to accomodate size
X characters and associated with the given file. When in
X doubt, use YY_BUF_SIZE for the size.
X
X - yy_switch_to_buffer( new_buffer ) switches the
X scanner's processing to scan for tokens from the given
X buffer, which must be a YY_BUFFER_STATE.
X
X - yy_delete_buffer( buffer ) deletes the given buffer.
X
XVALUES AVAILABLE TO THE USER
X - char *yytext holds the text of the current token. It
X may not be modified.
X
X - int yyleng holds the length of the current token. It
X may not be modified.
X
X - FILE *yyin is the file which by default flex reads
X from. It may be redefined but doing so only makes
X sense before scanning begins. Changing it in the mid-
X dle of scanning will have unexpected results since flex
X buffers its input. Once scanning terminates because an
X end-of-file has been seen, void yyrestart( FILE
X *new_file ) may be called to point yyin at the new
X input file.
X
X - FILE *yyout is the file to which ECHO actions are done.
X It can be reassigned by the user.
X
X - YY_CURRENT_BUFFER returns a YY_BUFFER_STATE handle to
X the current buffer.
X
XMACROS THE USER CAN REDEFINE
X - YY_DECL controls how the scanning routine is declared.
X By default, it is "int yylex()", or, if prototypes are
X being used, "int yylex(void)". This definition may be
X changed by redefining the "YY_DECL" macro. Note that
X if you give arguments to the scanning routine using a
X
X
X
XVersion 2.3 Last change: 26 May 1990 7
X
X
X
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
X K&R-style/non-prototyped function declaration, you must
X terminate the definition with a semi-colon (;).
X
X - The nature of how the scanner gets its input can be
X controlled by redefining the YY_INPUT macro.
X YY_INPUT's calling sequence is
X "YY_INPUT(buf,result,max_size)". Its action is to
X place up to max_size characters in the character array
X buf and return in the integer variable result either
X the number of characters read or the constant YY_NULL
X (0 on Unix systems) to indicate EOF. The default
X YY_INPUT reads from the global file-pointer "yyin". A
X sample redefinition of YY_INPUT (in the definitions
X section of the input file):
X
X %{
X #undef YY_INPUT
X #define YY_INPUT(buf,result,max_size) \
X { \
X int c = getchar(); \
X result = (c == EOF) ? YY_NULL : (buf[0] = c, 1); \
X }
X %}
X
X
X - When the scanner receives an end-of-file indication
X from YY_INPUT, it then checks the yywrap() function.
X If yywrap() returns false (zero), then it is assumed
X that the function has gone ahead and set up yyin to
X point to another input file, and scanning continues.
X If it returns true (non-zero), then the scanner ter-
X minates, returning 0 to its caller.
X
X The default yywrap() always returns 1. Presently, to
X redefine it you must first "#undef yywrap", as it is
X currently implemented as a macro. It is likely that
X yywrap() will soon be defined to be a function rather
X than a macro.
X
X - YY_USER_ACTION can be redefined to provide an action
X which is always executed prior to the matched rule's
X action.
X
X - The macro YY_USER_INIT may be redefined to provide an
X action which is always executed before the first scan.
X
X - In the generated scanner, the actions are all gathered
X in one large switch statement and separated using
X YY_BREAK, which may be redefined. By default, it is
X simply a "break", to separate each rule's action from
X the following rule's.
X
X
X
X
XVersion 2.3 Last change: 26 May 1990 8
X
X
X
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
XFILES
X flex.skel
X skeleton scanner.
X
X lex.yy.c
X generated scanner (called lexyy.c on some systems).
X
X lex.backtrack
X backtracking information for -b flag (called lex.bck on
X some systems).
X
X -lfl library with which to link the scanners.
X
XSEE ALSO
X flexdoc(1), lex(1), yacc(1), sed(1), awk(1).
X
X M. E. Lesk and E. Schmidt, LEX - Lexical Analyzer Generator
X
XDIAGNOSTICS
X reject_used_but_not_detected undefined or
X
X yymore_used_but_not_detected undefined - These errors can
X occur at compile time. They indicate that the scanner uses
X REJECT or yymore() but that flex failed to notice the fact,
X meaning that flex scanned the first two sections looking for
X occurrences of these actions and failed to find any, but
X somehow you snuck some in (via a #include file, for exam-
X ple). Make an explicit reference to the action in your flex
X input file. (Note that previously flex supported a
X %used/%unused mechanism for dealing with this problem; this
X feature is still supported but now deprecated, and will go
X away soon unless the author hears from people who can argue
X compellingly that they need it.)
X
X flex scanner jammed - a scanner compiled with -s has encoun-
X tered an input string which wasn't matched by any of its
X rules.
X
X flex input buffer overflowed - a scanner rule matched a
X string long enough to overflow the scanner's internal input
X buffer (16K bytes - controlled by YY_BUF_MAX in
X "flex.skel").
X
X scanner requires -8 flag - Your scanner specification
X includes recognizing 8-bit characters and you did not
X specify the -8 flag (and your site has not installed flex
X with -8 as the default).
X
X fatal flex scanner internal error--end of buffer missed -
X This can occur in an scanner which is reentered after a
X long-jump has jumped out (or over) the scanner's activation
X frame. Before reentering the scanner, use:
X
X
X
XVersion 2.3 Last change: 26 May 1990 9
X
X
X
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
X yyrestart( yyin );
X
X
X too many %t classes! - You managed to put every single char-
X acter into its own %t class. flex requires that at least
X one of the classes share characters.
X
XAUTHOR
X Vern Paxson, with the help of many ideas and much inspira-
X tion from Van Jacobson. Original version by Jef Poskanzer.
X
X See flexdoc(1) for additional credits and the address to
X send comments to.
X
XDEFICIENCIES / BUGS
X Some trailing context patterns cannot be properly matched
X and generate warning messages ("Dangerous trailing con-
X text"). These are patterns where the ending of the first
X part of the rule matches the beginning of the second part,
X such as "zx*/xy*", where the 'x*' matches the 'x' at the
X beginning of the trailing context. (Note that the POSIX
X draft states that the text matched by such patterns is unde-
X fined.)
X
X For some trailing context rules, parts which are actually
X fixed-length are not recognized as such, leading to the
X abovementioned performance loss. In particular, parts using
X '|' or {n} (such as "foo{3}") are always considered
X variable-length.
X
X Combining trailing context with the special '|' action can
X result in fixed trailing context being turned into the more
X expensive variable trailing context. For example, this hap-
X pens in the following example:
X
X %%
X abc |
X xyz/def
X
X
X Use of unput() invalidates yytext and yyleng.
X
X Use of unput() to push back more text than was matched can
X result in the pushed-back text matching a beginning-of-line
X ('^') rule even though it didn't come at the beginning of
X the line (though this is rare!).
X
X Pattern-matching of NUL's is substantially slower than
X matching other characters.
X
X flex does not generate correct #line directives for code
X internal to the scanner; thus, bugs in flex.skel yield bogus
X
X
X
XVersion 2.3 Last change: 26 May 1990 10
X
X
X
X
X
X
XFLEX(1) USER COMMANDS FLEX(1)
X
X
X
X line numbers.
X
X Due to both buffering of input and read-ahead, you cannot
X intermix calls to <stdio.h> routines, such as, for example,
X getchar(), with flex rules and expect it to work. Call
X input() instead.
X
X The total table entries listed by the -v flag excludes the
X number of table entries needed to determine what rule has
X been matched. The number of entries is equal to the number
X of DFA states if the scanner does not use REJECT, and some-
X what greater than the number of states if it does.
X
X REJECT cannot be used with the -f or -F options.
X
X Some of the macros, such as yywrap(), may in the future
X become functions which live in the -lfl library. This will
X doubtless break a lot of code, but may be required for
X POSIX-compliance.
X
X The flex internal algorithms need documentation.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
XVersion 2.3 Last change: 26 May 1990 11
X
X
X
END_OF_FILE
if test 25372 -ne `wc -c <'flex.Doc'`; then
echo shar: \"'flex.Doc'\" unpacked with wrong size!
fi
# end of 'flex.Doc'
fi
echo shar: End of archive 5 \(of 13\).
cp /dev/null ark5isdone
MISSING=""
for I in 1 2 3 4 5 6 7 8 9 10 11 12 13 ; do
if test ! -f ark${I}isdone ; then
MISSING="${MISSING} ${I}"
fi
done
if test "${MISSING}" = "" ; then
echo You have unpacked all 13 archives.
rm -f ark[1-9]isdone ark[1-9][0-9]isdone
else
echo You still need to unpack the following archives:
echo " " ${MISSING}
fi
## End of shell archive.
exit 0
--
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