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previous commits. At the time we search the pattern for the "must" string, we now compute the longest offset from the beginning of the pattern at which the must string might be found. If that offset is found to be infinite (through use of "+" or "*"), we set it to -1 to disable the heuristics applied later. After we are done with pre-matching, we use that offset and the point in the text at which the must string was found to compute the earliest point at which the pattern might be found. Special care should be taken here. The variable "start" is passed to the automata-processing functions fast() and slow() to indicate the point in the text at which they should start working from. The real beginning of the text is passed in a struct match variable m, which is used to check for anchors. That variable, though, is initialized with "start", so we must not adjust "start" before "m" is properly initialized. Simple tests showed a speed increase from 100% to 400%, but they were biased in that regexec() was called for the whole file instead of line by line, and parenthized subexpressions were not searched for. This change adds a single integer to the size of the "guts" structure, and does not change the ABI. Further improvements possible: Since the speed increase observed here is so huge, one intuitive optimization would be to introduce a bias in the function that computes the "must" string so as to prefer a smaller string with a finite offset over a larger one with an infinite offset. Tests have shown this to be a bad idea, though, as the cost of false pre-matches far outweights the benefits of a must offset, even in biased situations. A number of other improvements suggest themselves, though: * identify the cases where the pattern is identical to the must string, and avoid entering fast() and slow() in these cases. * compute the maximum offset from the must string to the end of the pattern, and use that to set the point at which fast() and slow() should give up trying to find a match, and return then return to pre-matching. * return all the way to pre-matching if a "match" was found and later invalidated by back reference processing. Since back references are evil and should be avoided anyway, this is of little use.
179 lines
7.5 KiB
C
179 lines
7.5 KiB
C
/*-
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* Copyright (c) 1992, 1993, 1994 Henry Spencer.
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* Copyright (c) 1992, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Henry Spencer.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)regex2.h 8.4 (Berkeley) 3/20/94
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*
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* $FreeBSD$
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*/
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/*
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* First, the stuff that ends up in the outside-world include file
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= typedef off_t regoff_t;
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= typedef struct {
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= int re_magic;
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= size_t re_nsub; // number of parenthesized subexpressions
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= const char *re_endp; // end pointer for REG_PEND
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= struct re_guts *re_g; // none of your business :-)
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= } regex_t;
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= typedef struct {
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= regoff_t rm_so; // start of match
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= regoff_t rm_eo; // end of match
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= } regmatch_t;
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*/
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/*
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* internals of regex_t
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*/
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#define MAGIC1 ((('r'^0200)<<8) | 'e')
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/*
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* The internal representation is a *strip*, a sequence of
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* operators ending with an endmarker. (Some terminology etc. is a
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* historical relic of earlier versions which used multiple strips.)
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* Certain oddities in the representation are there to permit running
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* the machinery backwards; in particular, any deviation from sequential
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* flow must be marked at both its source and its destination. Some
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* fine points:
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*
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* - OPLUS_ and O_PLUS are *inside* the loop they create.
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* - OQUEST_ and O_QUEST are *outside* the bypass they create.
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* - OCH_ and O_CH are *outside* the multi-way branch they create, while
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* OOR1 and OOR2 are respectively the end and the beginning of one of
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* the branches. Note that there is an implicit OOR2 following OCH_
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* and an implicit OOR1 preceding O_CH.
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*
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* In state representations, an operator's bit is on to signify a state
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* immediately *preceding* "execution" of that operator.
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*/
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typedef unsigned long sop; /* strip operator */
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typedef long sopno;
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#define OPRMASK 0xf8000000L
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#define OPDMASK 0x07ffffffL
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#define OPSHIFT ((unsigned)27)
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#define OP(n) ((n)&OPRMASK)
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#define OPND(n) ((n)&OPDMASK)
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#define SOP(op, opnd) ((op)|(opnd))
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/* operators meaning operand */
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/* (back, fwd are offsets) */
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#define OEND (1L<<OPSHIFT) /* endmarker - */
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#define OCHAR (2L<<OPSHIFT) /* character unsigned char */
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#define OBOL (3L<<OPSHIFT) /* left anchor - */
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#define OEOL (4L<<OPSHIFT) /* right anchor - */
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#define OANY (5L<<OPSHIFT) /* . - */
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#define OANYOF (6L<<OPSHIFT) /* [...] set number */
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#define OBACK_ (7L<<OPSHIFT) /* begin \d paren number */
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#define O_BACK (8L<<OPSHIFT) /* end \d paren number */
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#define OPLUS_ (9L<<OPSHIFT) /* + prefix fwd to suffix */
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#define O_PLUS (10L<<OPSHIFT) /* + suffix back to prefix */
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#define OQUEST_ (11L<<OPSHIFT) /* ? prefix fwd to suffix */
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#define O_QUEST (12L<<OPSHIFT) /* ? suffix back to prefix */
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#define OLPAREN (13L<<OPSHIFT) /* ( fwd to ) */
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#define ORPAREN (14L<<OPSHIFT) /* ) back to ( */
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#define OCH_ (15L<<OPSHIFT) /* begin choice fwd to OOR2 */
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#define OOR1 (16L<<OPSHIFT) /* | pt. 1 back to OOR1 or OCH_ */
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#define OOR2 (17L<<OPSHIFT) /* | pt. 2 fwd to OOR2 or O_CH */
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#define O_CH (18L<<OPSHIFT) /* end choice back to OOR1 */
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#define OBOW (19L<<OPSHIFT) /* begin word - */
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#define OEOW (20L<<OPSHIFT) /* end word - */
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/*
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* Structure for [] character-set representation. Character sets are
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* done as bit vectors, grouped 8 to a byte vector for compactness.
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* The individual set therefore has both a pointer to the byte vector
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* and a mask to pick out the relevant bit of each byte. A hash code
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* simplifies testing whether two sets could be identical.
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*
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* This will get trickier for multicharacter collating elements. As
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* preliminary hooks for dealing with such things, we also carry along
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* a string of multi-character elements, and decide the size of the
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* vectors at run time.
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*/
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typedef struct {
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uch *ptr; /* -> uch [csetsize] */
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uch mask; /* bit within array */
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short hash; /* hash code */
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size_t smultis;
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char *multis; /* -> char[smulti] ab\0cd\0ef\0\0 */
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} cset;
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/* note that CHadd and CHsub are unsafe, and CHIN doesn't yield 0/1 */
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#define CHadd(cs, c) ((cs)->ptr[(uch)(c)] |= (cs)->mask, (cs)->hash += (uch)(c))
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#define CHsub(cs, c) ((cs)->ptr[(uch)(c)] &= ~(cs)->mask, (cs)->hash -= (uch)(c))
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#define CHIN(cs, c) ((cs)->ptr[(uch)(c)] & (cs)->mask)
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#define MCadd(p, cs, cp) mcadd(p, cs, cp) /* regcomp() internal fns */
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#define MCsub(p, cs, cp) mcsub(p, cs, cp)
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#define MCin(p, cs, cp) mcin(p, cs, cp)
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/* stuff for character categories */
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typedef unsigned char cat_t;
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/*
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* main compiled-expression structure
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*/
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struct re_guts {
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int magic;
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# define MAGIC2 ((('R'^0200)<<8)|'E')
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sop *strip; /* malloced area for strip */
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int csetsize; /* number of bits in a cset vector */
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int ncsets; /* number of csets in use */
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cset *sets; /* -> cset [ncsets] */
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uch *setbits; /* -> uch[csetsize][ncsets/CHAR_BIT] */
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int cflags; /* copy of regcomp() cflags argument */
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sopno nstates; /* = number of sops */
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sopno firststate; /* the initial OEND (normally 0) */
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sopno laststate; /* the final OEND */
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int iflags; /* internal flags */
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# define USEBOL 01 /* used ^ */
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# define USEEOL 02 /* used $ */
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# define BAD 04 /* something wrong */
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int nbol; /* number of ^ used */
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int neol; /* number of $ used */
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int ncategories; /* how many character categories */
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cat_t *categories; /* ->catspace[-CHAR_MIN] */
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char *must; /* match must contain this string */
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int moffset; /* latest point at which must may be located */
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int *charjump; /* Boyer-Moore char jump table */
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int *matchjump; /* Boyer-Moore match jump table */
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int mlen; /* length of must */
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size_t nsub; /* copy of re_nsub */
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int backrefs; /* does it use back references? */
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sopno nplus; /* how deep does it nest +s? */
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/* catspace must be last */
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cat_t catspace[1]; /* actually [NC] */
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};
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/* misc utilities */
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#define OUT (CHAR_MAX+1) /* a non-character value */
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#define ISWORD(c) (isalnum((uch)(c)) || (c) == '_')
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