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psyclpc/src/regexp.c

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/*---------------------------------------------------------------------------
* Regular Expressions, implementing the minimal set required by P1003.
*
* Based on the code by Henry Spencer, and modified by Ian Phillipps,
* Joern Rennecke and Lars Duening.
*
* The original copyright and authors notice:
*
* Copyright (c) 1986 by University of Toronto.
* Written by Henry Spencer. Not derived from licensed software.
*
* Permission is granted to anyone to use this software for any
* purpose on any computer system, and to redistribute it freely,
* subject to the following restrictions:
*
* 1. The author is not responsible for the consequences of use of
* this software, no matter how awful, even if they arise
* from defects in it.
*
* 2. The origin of this software must not be misrepresented, either
* by explicit claim or by omission.
*
* 3. Altered versions must be plainly marked as such, and must not
* be misrepresented as being the original software.
*
* AUTHORS
*
* Mark H. Colburn, NAPS International (mark@jhereg.mn.org)
* Henry Spencer, University of Torronto (henry@utzoo.edu)
*
* Sponsored by The USENIX Association for public distribution.
*---------------------------------------------------------------------------
* Beware that some of this code is subtly aware of the way operator
* precedence is structured in regular expressions. Serious changes in
* regular-expression syntax might require a total rethink.
* TODO: This could be documented better.
*/
/* Headers */
#include "driver.h"
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include "regexp.h"
#include "simulate.h"
#include "xalloc.h"
#ifdef DEBUG
#include "main.h"
#endif
#include "i-eval_cost.h"
/*-------------------------------------------------------------------------*/
/* The "internal use only" fields in regexp.h are present to pass info from
* compile to execute that permits the execute phase to run lots faster on
* simple cases. They are:
*
* regstart char that must begin a match; '\0' if none obvious
* reganch is the match anchored (at beginning-of-line only)?
* regmust string (pointer into program) that match must include, or NULL
* regmlen length of regmust string
*
* Regstart and reganch permit very fast decisions on suitable starting points
* for a match, cutting down the work a lot. Regmust permits fast rejection
* of lines that cannot possibly match. The regmust tests are costly enough
* that hs_regcomp() supplies a regmust only if the r.e. contains something
* potentially expensive (at present, the only such thing detected is * or +
* at the start of the r.e., which can involve a lot of backup). Regmlen is
* supplied because the test in hs_regexec() needs it and hs_regcomp() is
* computing it anyway.
*
*----------------------------------------------------------------------------
*
* Structure for regexp "program". This is essentially a linear encoding
* of a nondeterministic finite-state machine (aka syntax charts or
* "railroad normal form" in parsing technology). Each node is an opcode
* plus a "nxt" pointer, possibly plus an operand. "Nxt" pointers of
* all nodes except BRANCH implement concatenation; a "nxt" pointer with
* a BRANCH on both ends of it is connecting two alternatives. (Here we
* have one of the subtle syntax dependencies: an individual BRANCH (as
* opposed to a collection of them) is never concatenated with anything
* because of operator precedence.) The operand of some types of node is
* a literal string; for others, it is a node leading into a sub-FSM. In
* particular, the operand of a BRANCH node is the first node of the branch.
* (NB this is *not* a tree structure: the tail of the branch connects
* to the thing following the set of BRANCHes.) The opcodes are:
*/
/* definition num opnd? meaning */
#define END 0 /* no End of program. */
#define BOL 1 /* no Match "" at beginning of line. */
#define EOL 2 /* no Match "" at end of line. */
#define ANY 3 /* no Match any one character. */
#define ANYOF 4 /* str Match any character in this string. */
#define ANYBUT 5 /* str Match any character not in this string. */
#define BRANCH 6 /* node Match this alternative, or the nxt... */
#define BACK 7 /* no Match "", "nxt" ptr points backward. */
#define EXACTLY 8 /* str Match this string. */
#define NOTHING 9 /* no Match empty string. */
#define STAR 10 /* node Match this (simple) thing 0 or more times. */
#define PLUS 11 /* node Match this (simple) thing 1 or more times */
#define WORDSTART 12 /* node matching a start of a word */
#define WORDEND 13 /* node matching an end of a word */
#define NOTEDGE 14 /* node matching anything not at word edge */
#define OPEN 20 /* no Mark this point in input as start of #n. */
/* OPEN+1 is number 1, etc. */
#define CLOSE (OPEN+NSUBEXP) /* no Analogous to OPEN. */
/* The first byte of the regexp internal "program" is actually this magic
* number; the start node begins in the second byte.
*/
#define MAGIC 0234
/* Opcode notes:
*
* BRANCH The set of branches constituting a single choice are hooked
* together with their "nxt" pointers, since precedence prevents
* anything being concatenated to any individual branch. The
* "nxt" pointer of the last BRANCH in a choice points to the
* thing following the whole choice. This is also where the
* final "nxt" pointer of each individual branch points; each
* branch starts with the operand node of a BRANCH node.
*
* BACK Normal "nxt" pointers all implicitly point forward; BACK
* exists to make loop structures possible.
*
* STAR,PLUS complex '*' and '+', are implemented as circular BRANCH
* structures using BACK. Simple cases (one character per match)
* are implemented with STAR for speed and to minimize recursive
* plunges.
*
* OPEN,CLOSE ...are numbered at compile time.
*/
/* A node is one char of opcode followed by two chars of "nxt" pointer.
* "Nxt" pointers are stored as two 8-bit pieces, high order first. The
* value is a positive offset from the opcode of the node containing it.
* An operand, if any, simply follows the node. (Note that much of the
* code generation knows about this implicit relationship.)
*
* Using two bytes for the "nxt" pointer is vast overkill for most things,
* but allows patterns to get big without disasters.
*/
#define OP(p) (*(p))
#define NEXT(p) (((*((p)+1)&0377)<<8) + (*((p)+2)&0377))
#define OPERAND(p) ((p) + 3)
/*
* Utility definitions.
*/
#define SPECIAL 0x100
#define LBRAC ('('|SPECIAL)
#define RBRAC (')'|SPECIAL)
#define ASTERIX ('*'|SPECIAL)
#define CROSS ('+'|SPECIAL)
#define OR_OP ('|'|SPECIAL)
#define DOLLAR ('$'|SPECIAL)
#define DOT ('.'|SPECIAL)
#define CARET ('^'|SPECIAL)
#define LSQBRAC ('['|SPECIAL)
#define RSQBRAC (']'|SPECIAL)
#define LSHBRAC ('<'|SPECIAL)
#define RSHBRAC ('>'|SPECIAL)
#define SLASHB ('B'|SPECIAL)
#define FAIL(m) { *ppErrMsg = m; return(NULL); }
#define XFREE(m) { if (m) xfree(m); m = NULL; }
#define ISMULT(c) ((c) == ASTERIX || (c) == CROSS)
#define META "^$.[()|+*\\"
#ifndef CHAR_BIT
#define UCHARAT(p) ((int)*(unsigned char *)(p))
#else
#define UCHARAT(p) ((int)*(p)&CHARBIT_MASK)
#endif
#define ISWORDPART(c) isalunum(c)
/*
* Flags to be passed up and down.
*/
#define HASWIDTH 01 /* Known never to match null string. */
#define SIMPLE 02 /* Simple enough to be STAR or PLUS operand. */
#define SPSTART 04 /* Starts with * */
#define WORST 0 /* Worst case. */
/*-------------------------------------------------------------------------*/
/* Global work variables for hs_regcomp().
*/
static short *regparse; /* Input-scan pointer. */
static int regnpar; /* () count. */
static unsigned char regdummy;
static unsigned char *regcode; /* Code-emit pointer; &regdummy = don't. */
static long regsize; /* Code size. */
static char **ppErrMsg; /* Place where to store an error message */
/* Global variables for hs_regexec().
*/
static unsigned char *reginput; /* String-input pointer. */
static unsigned char *regbol; /* Beginning of input, for ^ check. */
static char **regstartp; /* Pointer to startp array. */
static char **regendp; /* Ditto for endp. */
#ifdef DEBUG
Bool regnarrate = MY_FALSE; /* TRUE: dump matching operations */
#endif
/*-------------------------------------------------------------------------*/
/* Forward declarations */
static unsigned char *regatom (int *flagp);
static void regtail (unsigned char *p, unsigned char *val);
static void regoptail (unsigned char *p, unsigned char *val);
static void reginsert (char op, unsigned char *opnd);
static unsigned char *reg (Bool paren, int *flagp);
static int regtry(regexp*, char *);
static Bool regmatch(unsigned char *);
static int regrepeat(unsigned char *);
#ifdef DEBUG
static char *regprop(unsigned char *);
#endif
/*-------------------------------------------------------------------------*/
static void
regc (char b)
/* regc - emit (if appropriate) a byte of code
*/
{
if (regcode != &regdummy)
*regcode++ = b;
else
regsize++;
} /* regc() */
/*-------------------------------------------------------------------------*/
static unsigned char *
regnode (char op)
/* Emit a node, or at least count its size.
*/
{
unsigned char *ret;
unsigned char *ptr;
ret = regcode;
if (ret == &regdummy)
{
regsize += 3;
return ret;
}
ptr = ret;
*ptr++ = op;
*ptr++ = '\0'; /* Null "nxt" pointer. */
*ptr++ = '\0';
regcode = ptr;
return ret;
} /* regnode() */
/*-------------------------------------------------------------------------*/
static unsigned char *
regnext (unsigned char *p)
/* regnext - dig the "nxt" pointer out of a node
*/
{
int offset;
if (p == &regdummy)
return NULL;
offset = NEXT(p);
if (offset == 0)
return NULL;
if (OP(p) == BACK)
return (p - offset);
else
return (p + offset);
} /* regnext() */
/*-------------------------------------------------------------------------*/
static unsigned char *
regpiece (int *flagp)
/* regpiece - something followed by possible [*+]
*
* Note that the branching code sequence used for * and + is somewhat optimized:
* they use the same NOTHING node as both the endmarker for their branch
* list and the body of the last branch. It might seem that this node could
* be dispensed with entirely, but the endmarker role is not redundant.
*/
{
unsigned char *ret;
unsigned char *nxt;
short op;
int flags;
ret = regatom(&flags);
if (ret == NULL)
return NULL;
op = *regparse;
if (!ISMULT(op))
{
*flagp = flags;
return ret;
}
if (!(flags & HASWIDTH))
FAIL("* operand could be empty");
*flagp = (op != CROSS) ? (WORST | SPSTART) : (WORST | HASWIDTH);
if (op == ASTERIX && (flags & SIMPLE))
reginsert(STAR, ret);
else if (op == ASTERIX)
{
/* Emit x* as (x&|), where & means "self". */
reginsert(BRANCH, ret); /* Either x */
regoptail(ret, regnode(BACK)); /* and loop */
regoptail(ret, ret); /* back */
regtail(ret, regnode(BRANCH)); /* or */
regtail(ret, regnode(NOTHING)); /* null. */
}
else if (op == CROSS && (flags & SIMPLE))
reginsert(PLUS, ret);
else if (op == CROSS)
{
/* Emit x+ as x(&|), where & means "self" */
nxt = regnode(BRANCH); /* Either x */
regtail(ret, nxt);
regtail(regnode(BACK), ret); /* and loop back */
regtail(nxt, regnode(BRANCH)); /* or */
regtail(nxt, regnode(NOTHING)); /* null. */
}
regparse++;
if (ISMULT(*regparse))
FAIL("nested */+");
return ret;
} /* regpiece() */
/*-------------------------------------------------------------------------*/
static void
regtail (unsigned char *p, unsigned char *val)
/* regtail - set the next-pointer at the end of a node chain
*/
{
unsigned char *scan;
unsigned char *temp;
int offset;
if (p == &regdummy)
return;
/* Find last node. */
scan = p;
for (;;)
{
temp = regnext(scan);
if (temp == NULL)
break;
scan = temp;
}
if (OP(scan) == BACK)
offset = scan - val;
else
offset = val - scan;
*(scan + 1) = (offset >> 8) & 0377;
*(scan + 2) = offset & 0377;
} /* regtail() */
/*-------------------------------------------------------------------------*/
static void
regoptail (unsigned char *p, unsigned char *val)
/* regoptail - regtail on operand of first argument; nop if operandless
*/
{
/* "Operandless" and "op != BRANCH" are synonymous in practice. */
if (p == NULL || p == &regdummy || OP(p) != BRANCH)
return;
regtail(OPERAND(p), val);
} /* regoptail() */
/*-------------------------------------------------------------------------*/
static unsigned char *
regbranch (int *flagp)
/* One alternative of an | operator.
*
* Implements the concatenation operator.
*/
{
unsigned char *ret;
unsigned char *chain;
unsigned char *latest;
int flags;
*flagp = WORST; /* Tentatively. */
ret = regnode(BRANCH);
chain = NULL;
while (*regparse != '\0' && *regparse != OR_OP && *regparse != RBRAC)
{
latest = regpiece(&flags);
if (latest == NULL)
return NULL;
*flagp |= flags & HASWIDTH;
if (chain == NULL) /* First piece. */
*flagp |= flags & SPSTART;
else
regtail(chain, latest);
chain = latest;
}
if (chain == NULL) /* Loop ran zero times. */
regnode(NOTHING);
return ret;
} /* regbranch() */
/*-------------------------------------------------------------------------*/
static unsigned char *
regatom (int *flagp)
/* regatom - the lowest level
*
* Optimization: gobbles an entire sequence of ordinary characters so that
* it can turn them into a single node, which is smaller to store and
* faster to run.
*/
{
unsigned char *ret;
int flags;
*flagp = WORST; /* Tentatively. */
switch (*regparse++)
{
case CARET:
ret = regnode(BOL);
break;
case DOLLAR:
ret = regnode(EOL);
break;
case DOT:
ret = regnode(ANY);
*flagp |= HASWIDTH | SIMPLE;
break;
case LSHBRAC:
ret = regnode(WORDSTART);
break;
case RSHBRAC:
ret = regnode(WORDEND);
break;
case SLASHB:
ret = regnode(NOTEDGE);
break;
case LSQBRAC:
{
int class;
int classend;
if (*regparse == CARET)
{
/* Complement of range. */
ret = regnode(ANYBUT);
regparse++;
}
else
ret = regnode(ANYOF);
if (*regparse == RSQBRAC || *regparse == '-')
regc(*regparse++);
while (*regparse != '\0' && *regparse != RSQBRAC)
{
if (*regparse == '-')
{
regparse++;
if (*regparse == RSQBRAC || *regparse == '\0')
regc('-');
else
{
class = (CHARBIT_MASK & *(regparse - 2)) + 1;
classend = (CHARBIT_MASK & *(regparse));
if (class > classend + 1)
FAIL("invalid [] range");
for (; class <= classend; class++)
regc(class);
regparse++;
}
}
else
regc(*regparse++);
}
regc('\0');
if (*regparse != RSQBRAC)
FAIL("unmatched []");
regparse++;
*flagp |= HASWIDTH | SIMPLE;
break;
}
case LBRAC:
ret = reg(MY_TRUE, &flags);
if (ret == NULL)
return NULL;
*flagp |= flags & (HASWIDTH | SPSTART);
break;
case '\0':
case OR_OP:
case RBRAC:
FAIL("internal urp"); /* Supposed to be caught earlier. */
break;
case ASTERIX:
FAIL("* follows nothing");
break;
case CROSS:
FAIL("+ follows nothing");
break;
default:
{
int len;
short ender;
regparse--;
for ( len = 0
; regparse[len]
&& !(regparse[len]&SPECIAL)
&& regparse[len] != RSQBRAC
; len++) NOOP;
if (len <= 0)
{
if (len == 0 && regparse[len] == RSQBRAC)
{
FAIL("unmatched []");
}
FAIL("internal disaster");
}
ender = *(regparse + len);
if (len > 1 && ISMULT(ender))
len--; /* Back off clear of * operand. */
*flagp |= HASWIDTH;
if (len == 1)
*flagp |= SIMPLE;
ret = regnode(EXACTLY);
while (len > 0)
{
regc(*regparse++);
len--;
}
regc('\0');
break;
}
}
return ret;
} /* regatom() */
/*-------------------------------------------------------------------------*/
static void
reginsert (char op, unsigned char *opnd)
/* reginsert - insert an operator in front of already-emitted operand
*
* Means relocating the operand.
*/
{
unsigned char *src;
unsigned char *dst;
unsigned char *place;
if (regcode == &regdummy)
{
regsize += 3;
return;
}
src = regcode;
regcode += 3;
dst = regcode;
while (src > opnd)
*--dst = *--src;
place = opnd; /* Op node, where operand used to be. */
*place++ = op;
*place++ = '\0';
*place++ = '\0';
} /* reginsert() */
/*-------------------------------------------------------------------------*/
static unsigned char *
reg (Bool paren, int *flagp)
/* Compile a top-level regular expression, ie. the main body or parenthesized
* thing (<paren> is true in the latter case).
*
* Caller must absorb opening parenthesis.
*
* Combining parenthesis handling with the base level of regular expression
* is a trifle forced, but the need to tie the tails of the branches to what
* follows makes it hard to avoid.
*/
{
unsigned char *ret;
unsigned char *br;
unsigned char *ender;
int parno = 0;
int flags;
*flagp = HASWIDTH; /* Tentatively. */
/* Make an OPEN node, if parenthesized. */
if (paren)
{
if (regnpar >= NSUBEXP)
FAIL("too many ()");
parno = regnpar;
regnpar++;
ret = regnode(OPEN + parno);
}
else
ret = NULL;
/* Pick up the branches, linking them together. */
br = regbranch(&flags);
if (br == NULL)
return NULL;
if (ret != NULL)
regtail(ret, br); /* OPEN -> first. */
else
ret = br;
if (!(flags & HASWIDTH))
*flagp &= ~HASWIDTH;
*flagp |= flags & SPSTART;
while (*regparse == OR_OP)
{
regparse++;
br = regbranch(&flags);
if (br == NULL)
return NULL;
regtail(ret, br); /* BRANCH -> BRANCH. */
if (!(flags & HASWIDTH))
*flagp &= ~HASWIDTH;
*flagp |= flags & SPSTART;
}
/* Make a closing node, and hook it on the end. */
ender = regnode((paren) ? CLOSE + parno : END);
regtail(ret, ender);
/* Hook the tails of the branches to the closing node. */
for (br = ret; br != NULL; br = regnext(br))
regoptail(br, ender);
/* Check for proper termination. */
if (paren && *regparse++ != RBRAC)
{
FAIL("unmatched ()");
}
else if (!paren && *regparse != '\0')
{
if (*regparse == RBRAC)
{
FAIL("unmatched ()");
}
else
FAIL("junk on end");/* "Can't happen". */
/* NOTREACHED */
}
return (ret);
} /* reg() */
/*-------------------------------------------------------------------------*/
regexp *
hs_regcomp (unsigned char *expr, Bool excompat
, char ** errmsg, int * erridx)
/* Compile a regular expression in <expr> into internal code; if <excompat>
* is TRUE; \( \) operators like in Unix ex are allowed. Result is the
* regexp structure with the program.
*
* If an error occured during the compilation, *<errmsg> is set to the
* static string with the error message, *<erridx> to the approximate
* position in <expr> where the error happened, and the function returns NULL.
*
* We can't allocate space until we know how big the compiled form will be,
* but we can't compile it (and thus know how big it is) until we've got a
* place to put the code. So we cheat: we compile it twice, once with code
* generation turned off and size counting turned on, and once "for real".
* This also means that we don't allocate space until we are sure that the
* thing really will compile successfully, and we never have to move the
* code and thus invalidate pointers into it. (Note that it has to be in
* one piece because free() must be able to free it all.)
*
* Beware that the optimization-preparation code in here knows about some
* of the structure of the compiled regexp.
*/
{
unsigned char *scan;
unsigned char *longest;
int len;
int flags;
short *dest, c;
regexp *rc; /* Holds the result to be returned */
regexp *r = NULL; /* The resulting regexp */
short *expr2 = NULL; /* Expression currently compiled */
ppErrMsg = errmsg;
*ppErrMsg = NULL;
*erridx = 0;
#ifdef DEBUG
/* Check the invariant for the global vars */
if (r != NULL)
{
debug_message("DEBUG: (regexp:regcomp) r == %p\n", r);
#ifdef VERBOSE
fprintf(stderr, "DEBUG: (regexp:regcomp) r == %p\n", r);
#endif
r = NULL;
}
if (expr2 != NULL)
{
debug_message("DEBUG: (regexp:regcomp) expr2 == %p\n", expr2);
#ifdef VERBOSE
fprintf(stderr, "DEBUG: (regexp:regcomp) expr2 == %p\n", expr2);
#endif
expr2 = NULL;
}
#endif
if (expr == NULL)
FAIL("NULL argument");
/* Get some memory, maybe slightly more than needed */
expr2 = xalloc( (strlen((char *)expr)+1) * (sizeof(short[8])/sizeof(char[8])) );
if (expr2 == NULL)
FAIL("out of space");
/* Copy the expression into expr2 for compilation, marking
* the special characters.
*/
for (scan = expr, dest = expr2; '\0' != (c = *scan++); )
{
switch (c)
{
case '(':
case ')':
*dest++ = excompat ? c : c | SPECIAL;
break;
case '.':
case '*':
case '+':
case '|':
case '$':
case '^':
case '[':
case ']':
*dest++ = c | SPECIAL;
break;
case '\\':
switch ( c = *scan++ )
{
case '(':
case ')':
*dest++ = excompat ? c | SPECIAL : c;
break;
case '<':
case '>':
case 'B':
*dest++ = c | SPECIAL;
break;
case '{':
case '}':
XFREE(expr2);
FAIL("sorry, unimplemented operator {}");
case 'b': *dest++ = '\b'; break;
case 't': *dest++ = '\t'; break;
case 'r': *dest++ = '\r'; break;
case '\0': scan--;
default:
*dest++ = c;
}
break;
default:
*dest++ = c;
}
}
*dest = '\0';
/* First pass: determine size, legality. */
regparse = expr2;
regnpar = 1;
regsize = 0L;
regcode = &regdummy;
regc(MAGIC);
if (reg(MY_FALSE, &flags) == NULL)
{
*erridx = regparse - expr2;
XFREE(expr2);
return NULL;
}
/* Small enough for pointer-storage convention? */
if (regsize >= 32767L) /* TODO: Probably could be 65535L. */
{
/* Probably could be any amount of memory we could spare... */
*erridx = regparse - expr2;
XFREE(expr2);
FAIL("regexp too big");
}
/* Allocate space. */
r = xalloc(sizeof(regexp) + (size_t) regsize);
if (r == NULL)
{
*erridx = regparse - expr2;
XFREE(expr2);
FAIL("out of space");
}
r->regalloc = sizeof(regexp)+regsize;
/* Second pass: emit code. */
regparse = expr2;
regnpar = 1;
regcode = r->program;
regc(MAGIC);
if (reg(MY_FALSE, &flags) == NULL)
{
*erridx = regparse - expr2;
XFREE(r);
XFREE(expr2);
return NULL;
}
/* Dig out information for optimizations. */
r->regstart = '\0'; /* Worst-case defaults. */
r->reganch = 0;
r->regmust = NULL;
r->regmlen = 0;
scan = r->program + 1; /* First BRANCH. */
if (OP(regnext(scan)) == END)
{
/* Only one top-level choice. */
scan = OPERAND(scan);
/* Starting-point info. */
if (OP(scan) == EXACTLY)
r->regstart = *OPERAND(scan);
else if (OP(scan) == BOL)
r->reganch++;
/* If there's something expensive in the r.e., find the longest
* literal string that must appear and make it the regmust. Resolve
* ties in favor of later strings, since the regstart check works
* with the beginning of the r.e. and avoiding duplication
* strengthens checking. Not a strong reason, but sufficient in the
* absence of others.
*/
if (flags & SPSTART)
{
longest = NULL;
len = 0;
for (; scan != NULL; scan = regnext(scan))
if (OP(scan) == EXACTLY && (int)strlen((char *)OPERAND(scan)) >= len)
{
longest = OPERAND(scan);
len = strlen((char *)OPERAND(scan));
}
r->regmust = longest;
r->regmlen = len;
}
}
/* Done: reset the global vars and return the result */
XFREE(expr2);
rc = r; r = NULL;
return rc;
} /* hs_regcomp() */
/*-------------------------------------------------------------------------*/
int
hs_regexec (regexp *prog, char *string, char *start)
/* Match the regexp <prog> against the <string> starting at the
* position <start>.
*
* Return one of the RE_ERROR_ codes depending on the result.
*/
{
int rc;
char *s;
/* Be paranoid... */
if (prog == NULL || string == NULL)
return RE_ERROR_NULL;
/* Check validity of program. */
if (UCHARAT(prog->program) != MAGIC)
{
return RE_ERROR_CORRUPT;
}
/* If there is a "must appear" string, look for it. */
if (prog->regmust != NULL)
{
s = string;
while ((s = strchr(s, prog->regmust[0])) != NULL)
{
if (strncmp(s, (char *)(prog->regmust), prog->regmlen) == 0)
break; /* Found it. */
s++;
}
if (s == NULL) /* Not present. */
return RE_NOMATCH;
}
/* Mark beginning of line for ^ . */
regbol = (unsigned char *)start;
/* Simplest case: anchored match need be tried only once. */
if (prog->reganch)
return regtry(prog, string);
/* Messy cases: unanchored match. */
s = string;
if (prog->regstart != '\0')
/* We know what char it must start with. */
while ((s = strchr(s, prog->regstart)) != NULL)
{
rc = regtry(prog,s);
if (rc != RE_NOMATCH)
return rc;
s++;
}
else
/* We don't -- general case. */
do {
rc = regtry(prog,s);
if (rc != RE_NOMATCH)
return rc;
} while (*s++ != '\0');
/* Failure. */
return RE_NOMATCH;
} /* hs_regexec() */
/*-------------------------------------------------------------------------*/
static int
regtry (regexp *prog, char *string)
/* regtry - try match at specific point
*/
{
int i, rc;
char **sp;
char **ep;
reginput = (unsigned char *)string;
regstartp = prog->startp;
regendp = prog->endp;
sp = prog->startp;
ep = prog->endp;
for (i = NSUBEXP; i > 0; i--)
{
*sp++ = NULL;
*ep++ = NULL;
}
rc = regmatch(prog->program + 1);
if (rc == RE_MATCH)
{
prog->startp[0] = string;
prog->endp[0] = (char *)reginput;
return RE_MATCH;
}
else
return rc;
} /* regtry() */
/*-------------------------------------------------------------------------*/
static Bool
regmatch (unsigned char *prog)
/* regmatch - main matching routine
*
* Conceptually the strategy is simple: check to see whether the current
* node matches, call self recursively to see whether the rest matches,
* and then act accordingly. In practice we make some effort to avoid
* recursion, in particular by going through "ordinary" nodes (that don't
* need to know whether the rest of the match failed) by a loop instead of
* by recursion.
*/
{
unsigned char *scan; /* Current node. */
unsigned char *nxt; /* nxt node. */
scan = prog;
#ifdef DEBUG
if (scan != NULL && regnarrate)
fprintf(stderr, "%s(\n", regprop(scan));
#endif
while (scan != NULL)
{
#ifdef DEBUG
if (regnarrate)
fprintf(stderr, "%s...\n", regprop(scan));
#endif
nxt = regnext(scan);
switch (OP(scan))
{
case BOL:
if (reginput != regbol)
return RE_NOMATCH;
break;
case EOL:
if (*reginput != '\0')
return RE_NOMATCH;
break;
case ANY:
if (*reginput == '\0')
return RE_NOMATCH;
reginput++;
break;
case WORDSTART:
if (reginput == regbol)
break;
if (*reginput == '\0'
|| ISWORDPART( *(reginput-1) ) || !ISWORDPART( *reginput ) )
return RE_NOMATCH;
break;
case WORDEND:
if (*reginput == '\0')
break;
if ( reginput == regbol
|| !ISWORDPART( *(reginput-1) ) || ISWORDPART( *reginput ) )
return RE_NOMATCH;
break;
case NOTEDGE:
if (reginput == regbol)
{
if (ISWORDPART(*reginput))
return RE_NOMATCH;
break;
}
if ( ISWORDPART( *(reginput-1) ) != ISWORDPART( *reginput ) )
return RE_NOMATCH;
break;
case EXACTLY:
{
int len;
unsigned char *opnd;
opnd = OPERAND(scan);
/* Inline the first character, for speed. */
if (*opnd != *reginput)
return RE_NOMATCH;
len = strlen((char *)opnd);
if (len > 1 && strncmp((char *)opnd, (char *)reginput, len) != 0)
return RE_NOMATCH;
reginput += len;
break;
}
case ANYOF:
if (*reginput == '\0'
|| strchr((char *)OPERAND(scan), *reginput) == NULL)
return RE_NOMATCH;
reginput++;
break;
case ANYBUT:
if (*reginput == '\0'
|| strchr((char *)OPERAND(scan), *reginput) != NULL)
return RE_NOMATCH;
reginput++;
break;
case NOTHING:
break;
case BACK:
break;
case BRANCH:
{
unsigned char *save;
if (OP(nxt) != BRANCH) /* No choice. */
nxt = OPERAND(scan); /* Avoid recursion. */
else
{
do {
int rc;
save = reginput;
rc = regmatch(OPERAND(scan));
if (rc != RE_NOMATCH)
return rc;
reginput = save;
scan = regnext(scan);
} while (scan != NULL && OP(scan) == BRANCH);
return RE_NOMATCH;
/* NOTREACHED */
}
break;
}
case STAR:
case PLUS:
{
unsigned char nextch;
int no;
unsigned char *save;
int minimum;
/* Lookahead to avoid useless match attempts when we know
* what character comes next.
*/
nextch = '\0';
if (OP(nxt) == EXACTLY)
nextch = *OPERAND(nxt);
minimum = (OP(scan) == STAR) ? 0 : 1;
save = reginput;
no = regrepeat(OPERAND(scan));
while (no >= minimum)
{
/* If it could work, try it. */
if (nextch == '\0' || *reginput == nextch)
{
int rc;
rc = regmatch(nxt);
if (rc != RE_NOMATCH)
return rc;
}
/* Couldn't or didn't -- back up. */
no--;
reginput = save + no;
if (add_eval_cost(1))
return RE_ERROR_BACKTRACK;
}
return RE_NOMATCH;
break;
}
case END:
return MY_TRUE; /* Success! */
break;
default:
if (OP(scan) > OPEN && OP(scan) < OPEN+NSUBEXP)
{
int no, rc;
unsigned char *save;
no = OP(scan) - OPEN;
save = reginput;
rc = regmatch(nxt);
if (rc == RE_MATCH)
{
/* Don't set startp if some later invocation of the same
* parentheses already has.
*/
if (regstartp[no] == NULL)
regstartp[no] = (char *)save;
return RE_MATCH;
}
else
return rc;
}
else if (OP(scan) > CLOSE && OP(scan) < CLOSE+NSUBEXP)
{
int no, rc;
unsigned char *save;
no = OP(scan) - CLOSE;
save = reginput;
rc = regmatch(nxt);
if (rc == RE_MATCH)
{
/*
* Don't set endp if some later invocation of the same
* parentheses already has.
*/
if (regendp[no] == NULL)
regendp[no] = (char *)save;
return RE_MATCH;
} else
return rc;
}
else
{
return RE_ERROR_CORRUPT;
}
break;
}
scan = nxt;
}
/* We get here only if there's trouble -- normally "case END" is the
* terminating point.
*/
return RE_ERROR_CORRUPT;
} /* regmatch() */
/*-------------------------------------------------------------------------*/
static int
regrepeat (unsigned char *p)
/* regrepeat - repeatedly match something simple, report how many
*/
{
int count = 0;
unsigned char *scan;
unsigned char *opnd;
scan = reginput;
opnd = OPERAND(p);
switch (OP(p))
{
case ANY:
count = strlen((char *)scan);
scan += count;
break;
case EXACTLY:
while (*opnd == *scan)
{
count++;
scan++;
}
break;
case ANYOF:
while (*scan != '\0' && strchr((char *)opnd, *scan) != NULL)
{
count++;
scan++;
}
break;
case ANYBUT:
while (*scan != '\0' && strchr((char *)opnd, *scan) == NULL)
{
count++;
scan++;
}
break;
default: /* Oh dear. Called inappropriately. */
fatal("regexp: internal foulup\n");
count = 0; /* Best compromise. */
break;
}
reginput = scan;
return count;
} /* regrepeat() */
/*-------------------------------------------------------------------------*/
#ifdef DEBUG
/*-------------------------------------------------------------------------*/
static char *
regprop (unsigned char *op)
/* regprop - printable representation of opcode
*/
{
char *p = NULL;
static char buf[50];
strcpy(buf, ":");
switch (OP(op))
{
case BOL:
p = "BOL";
break;
case EOL:
p = "EOL";
break;
case ANY:
p = "ANY";
break;
case ANYOF:
p = "ANYOF";
break;
case ANYBUT:
p = "ANYBUT";
break;
case BRANCH:
p = "BRANCH";
break;
case EXACTLY:
p = "EXACTLY";
break;
case NOTHING:
p = "NOTHING";
break;
case BACK:
p = "BACK";
break;
case END:
p = "END";
break;
case STAR:
p = "STAR";
break;
case PLUS:
p = "PLUS";
break;
case WORDSTART:
p = "WORDSTART";
break;
case WORDEND:
p = "WORDEND";
break;
case NOTEDGE:
p = "NOTEDGE";
break;
default:
if (OP(op) > OPEN && OP(op) < OPEN+NSUBEXP)
{
sprintf(buf + strlen(buf), "OPEN%d", OP(op) - OPEN);
p = (char *)NULL;
}
else if (OP(op) > CLOSE && OP(op) < CLOSE+NSUBEXP)
{
sprintf(buf + strlen(buf), "CLOSE%d", OP(op) - CLOSE);
p = (char *)NULL;
}
else
errorf("corrupted opcode\n");
break;
}
if (p != (char *)NULL)
strcat(buf, p);
return buf;
} /* regprop() */
/*-------------------------------------------------------------------------*/
void
hs_regdump (regexp *rg)
/* regdump - dump a regexp onto stdout in vaguely comprehensible form
*/
{
unsigned char *s;
unsigned char op = EXACTLY; /* Arbitrary non-END op. */
unsigned char *nxt;
s = rg->program + 1;
while (op != END) /* While that wasn't END last time... */
{
op = OP(s);
printf("%2ld%s", (long)(s - rg->program), regprop(s)); /* Where, what. */
nxt = regnext(s);
if (nxt == NULL) /* nxt ptr. */
printf("(0)");
else
printf("(%ld)", (long)(s - rg->program) + (nxt - s));
s += 3;
if (op == ANYOF || op == ANYBUT || op == EXACTLY)
{
/* Literal string, where present. */
while (*s != '\0')
{
putchar(*s);
s++;
}
s++;
}
putchar('\n');
}
/* Header fields of interest. */
if (rg->regstart != '\0')
printf("start `%c' ", rg->regstart);
if (rg->reganch)
printf("anchored ");
if (rg->regmust != NULL)
printf("must have \"%s\"", rg->regmust);
printf("\n");
} /* hs_regdump() */
#endif /* DEBUG */
/*-------------------------------------------------------------------------*/
#if 0
/*
* The following is provided for those people who do not have strcspn() in
* their C libraries. They should get off their butts and do something
* about it; at least one public-domain implementation of those (highly
* useful) string routines has been published on Usenet.
*/
/*
* strcspn - find length of initial segment of s1 consisting entirely
* of characters not from s2
*/
#ifdef __STDC__
static int strcspn(char *s1, char *s2)
#else
static int strcspn(s1, s2)
char *s1;
char *s2;
#endif
{
register char *scan1;
register char *scan2;
register int count;
count = 0;
for (scan1 = s1; *scan1 != '\0'; scan1++) {
for (scan2 = s2; *scan2 != '\0';) /* ++ moved down. */
if (*scan1 == *scan2++)
return (count);
count++;
}
return (count);
}
#endif
/***************************************************************************/
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