/*
* TclRegComp and TclRegExec -- TclRegSub is elsewhere
*
* 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.
*
* 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.
*
* *** NOTE: this code has been altered slightly for use in Tcl: ***
* *** 1. Use ckalloc and ckfree instead of malloc and free. ***
* *** 2. Add extra argument to regexp to specify the real ***
* *** start of the string separately from the start of the ***
* *** current search. This is needed to search for multiple ***
* *** matches within a string. ***
* *** 3. Names have been changed, e.g. from regcomp to ***
* *** TclRegComp, to avoid clashes with other ***
* *** regexp implementations used by applications. ***
* *** 4. Added errMsg declaration and TclRegError procedure ***
* *** 5. Various lint-like things, such as casting arguments ***
* *** in procedure calls. ***
*
* *** NOTE: This code has been altered for use in MT-Sturdy Tcl ***
* *** 1. All use of static variables has been changed to access ***
* *** fields of a structure. ***
* *** 2. This in addition to changes to TclRegError makes the ***
* *** code multi-thread safe. ***
*
* RCS: @(#) $Id: regexp.c,v 1.2 1998/09/14 18:39:57 stanton Exp $
*/
#include "tclInt.h"
#include "tclPort.h"
/*
* The variable below is set to NULL before invoking regexp functions
* and checked after those functions. If an error occurred then TclRegError
* will set the variable to point to a (static) error message. This
* mechanism unfortunately does not support multi-threading, but the
* procedures TclRegError and TclGetRegError can be modified to use
* thread-specific storage for the variable and thereby make the code
* thread-safe.
*/
static char *errMsg = NULL;
/*
* 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 TclRegComp() 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 TclRegExec() needs it and TclRegComp() 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 "next" pointer, possibly plus an operand. "Next" pointers of
* all nodes except BRANCH implement concatenation; a "next" 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 number 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 next... */
#define BACK 7 /* no Match "", "next" 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 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. */
/*
* Opcode notes:
*
* BRANCH The set of branches constituting a single choice are hooked
* together with their "next" pointers, since precedence prevents
* anything being concatenated to any individual branch. The
* "next" pointer of the last BRANCH in a choice points to the
* thing following the whole choice. This is also where the
* final "next" pointer of each individual branch points; each
* branch starts with the operand node of a BRANCH node.
*
* BACK Normal "next" pointers all implicitly point forward; BACK
* exists to make loop structures possible.
*
* STAR,PLUS '?', and complex '*' and '+', are implemented as circular
* BRANCH structures using BACK. Simple cases (one character
* per match) are implemented with STAR and PLUS 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 "next" pointer.
* "Next" 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 "next" 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)
/*
* See regmagic.h for one further detail of program structure.
*/
/*
* Utility definitions.
*/
#ifndef CHARBITS
#define UCHARAT(p) ((int)*(unsigned char *)(p))
#else
#define UCHARAT(p) ((int)*(p)&CHARBITS)
#endif
#define FAIL(m) { TclRegError(m); return(NULL); }
#define ISMULT(c) ((c) == '*' || (c) == '+' || (c) == '?')
#define META "^$.[()|?+*\\"
/*
* Flags to be passed up and down.
*/
#define HASWIDTH 01 /* Known never to match null string. */
#define SIMPLE 02 /* Simple enough to be STAR/PLUS operand. */
#define SPSTART 04 /* Starts with * or +. */
#define WORST 0 /* Worst case. */
/*
* Global work variables for TclRegComp().
*/
struct regcomp_state {
char *regparse; /* Input-scan pointer. */
int regnpar; /* () count. */
char *regcode; /* Code-emit pointer; ®dummy = don't. */
long regsize; /* Code size. */
};
static char regdummy;
/*
* The first byte of the regexp internal "program" is actually this magic
* number; the start node begins in the second byte.
*/
#define MAGIC 0234
/*
* Forward declarations for TclRegComp()'s friends.
*/
static char * reg _ANSI_ARGS_((int paren, int *flagp,
struct regcomp_state *rcstate));
static char * regatom _ANSI_ARGS_((int *flagp,
struct regcomp_state *rcstate));
static char * regbranch _ANSI_ARGS_((int *flagp,
struct regcomp_state *rcstate));
static void regc _ANSI_ARGS_((int b,
struct regcomp_state *rcstate));
static void reginsert _ANSI_ARGS_((int op, char *opnd,
struct regcomp_state *rcstate));
static char * regnext _ANSI_ARGS_((char *p));
static char * regnode _ANSI_ARGS_((int op,
struct regcomp_state *rcstate));
static void regoptail _ANSI_ARGS_((char *p, char *val));
static char * regpiece _ANSI_ARGS_((int *flagp,
struct regcomp_state *rcstate));
static void regtail _ANSI_ARGS_((char *p, char *val));
#ifdef STRCSPN
static int strcspn _ANSI_ARGS_((char *s1, char *s2));
#endif
/*
- TclRegComp - compile a regular expression into internal code
*
* 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.
*/
regexp *
TclRegComp(exp)
char *exp;
{
register regexp *r;
register char *scan;
register char *longest;
register int len;
int flags;
struct regcomp_state state;
struct regcomp_state *rcstate= &state;
if (exp == NULL)
FAIL("NULL argument");
/* First pass: determine size, legality. */
rcstate->regparse = exp;
rcstate->regnpar = 1;
rcstate->regsize = 0L;
rcstate->regcode = ®dummy;
regc(MAGIC, rcstate);
if (reg(0, &flags, rcstate) == NULL)
return(NULL);
/* Small enough for pointer-storage convention? */
if (rcstate->regsize >= 32767L) /* Probably could be 65535L. */
FAIL("regexp too big");
/* Allocate space. */
r = (regexp *)ckalloc(sizeof(regexp) + (unsigned)rcstate->regsize);
if (r == NULL)
FAIL("out of space");
/* Second pass: emit code. */
rcstate->regparse = exp;
rcstate->regnpar = 1;
rcstate->regcode = r->program;
regc(MAGIC, rcstate);
if (reg(0, &flags, rcstate) == NULL)
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(OPERAND(scan))) >= len) {
longest = OPERAND(scan);
len = strlen(OPERAND(scan));
}
r->regmust = longest;
r->regmlen = len;
}
}
return(r);
}
/*
- reg - regular expression, i.e. main body or parenthesized thing
*
* 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.
*/
static char *
reg(paren, flagp, rcstate)
int paren; /* Parenthesized? */
int *flagp;
struct regcomp_state *rcstate;
{
register char *ret;
register char *br;
register char *ender;
register int parno = 0;
int flags;
*flagp = HASWIDTH; /* Tentatively. */
/* Make an OPEN node, if parenthesized. */
if (paren) {
if (rcstate->regnpar >= NSUBEXP)
FAIL("too many ()");
parno = rcstate->regnpar;
rcstate->regnpar++;
ret = regnode(OPEN+parno,rcstate);
} else
ret = NULL;
/* Pick up the branches, linking them together. */
br = regbranch(&flags,rcstate);
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 (*rcstate->regparse == '|') {
rcstate->regparse++;
br = regbranch(&flags,rcstate);
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,rcstate);
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 && *rcstate->regparse++ != ')') {
FAIL("unmatched ()");
} else if (!paren && *rcstate->regparse != '\0') {
if (*rcstate->regparse == ')') {
FAIL("unmatched ()");
} else
FAIL("junk on end"); /* "Can't happen". */
/* NOTREACHED */
}
return(ret);
}
/*
- regbranch - one alternative of an | operator
*
* Implements the concatenation operator.
*/
static char *
regbranch(flagp, rcstate)
int *flagp;
struct regcomp_state *rcstate;
{
register char *ret;
register char *chain;
register char *latest;
int flags;
*flagp = WORST; /* Tentatively. */
ret = regnode(BRANCH,rcstate);
chain = NULL;
while (*rcstate->regparse != '\0' && *rcstate->regparse != '|' &&
*rcstate->regparse != ')') {
latest = regpiece(&flags, rcstate);
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. */
(void) regnode(NOTHING,rcstate);
return(ret);
}
/*
- regpiece - something followed by possible [*+?]
*
* Note that the branching code sequences used for ? and the general cases
* of * and + are 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.
*/
static char *
regpiece(flagp, rcstate)
int *flagp;
struct regcomp_state *rcstate;
{
register char *ret;
register char op;
register char *next;
int flags;
ret = regatom(&flags,rcstate);
if (ret == NULL)
return(NULL);
op = *rcstate->regparse;
if (!ISMULT(op)) {
*flagp = flags;
return(ret);
}
if (!(flags&HASWIDTH) && op != '?')
FAIL("*+ operand could be empty");
*flagp = (op != '+') ? (WORST|SPSTART) : (WORST|HASWIDTH);
if (op == '*' && (flags&SIMPLE))
reginsert(STAR, ret, rcstate);
else if (op == '*') {
/* Emit x* as (x&|), where & means "self". */
reginsert(BRANCH, ret, rcstate); /* Either x */
regoptail(ret, regnode(BACK,rcstate)); /* and loop */
regoptail(ret, ret); /* back */
regtail(ret, regnode(BRANCH,rcstate)); /* or */
regtail(ret, regnode(NOTHING,rcstate)); /* null. */
} else if (op == '+' && (flags&SIMPLE))
reginsert(PLUS, ret, rcstate);
else if (op == '+') {
/* Emit x+ as x(&|), where & means "self". */
next = regnode(BRANCH,rcstate); /* Either */
regtail(ret, next);
regtail(regnode(BACK,rcstate), ret); /* loop back */
regtail(next, regnode(BRANCH,rcstate)); /* or */
regtail(ret, regnode(NOTHING,rcstate)); /* null. */
} else if (op == '?') {
/* Emit x? as (x|) */
reginsert(BRANCH, ret, rcstate); /* Either x */
regtail(ret, regnode(BRANCH,rcstate)); /* or */
next = regnode(NOTHING,rcstate); /* null. */
regtail(ret, next);
regoptail(ret, next);
}
rcstate->regparse++;
if (ISMULT(*rcstate->regparse))
FAIL("nested *?+");
return(ret);
}
/*
- 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. Backslashed characters are exceptions, each becoming a
* separate node; the code is simpler that way and it's not worth fixing.
*/
static char *
regatom(flagp, rcstate)
int *flagp;
struct regcomp_state *rcstate;
{
register char *ret;
int flags;
*flagp = WORST; /* Tentatively. */
switch (*rcstate->regparse++) {
case '^':
ret = regnode(BOL,rcstate);
break;
case '$':
ret = regnode(EOL,rcstate);
break;
case '.':
ret = regnode(ANY,rcstate);
*flagp |= HASWIDTH|SIMPLE;
break;
case '[': {
register int clss;
register int classend;
if (*rcstate->regparse == '^') { /* Complement of range. */
ret = regnode(ANYBUT,rcstate);
rcstate->regparse++;
} else
ret = regnode(ANYOF,rcstate);
if (*rcstate->regparse == ']' || *rcstate->regparse == '-')
regc(*rcstate->regparse++,rcstate);
while (*rcstate->regparse != '\0' && *rcstate->regparse != ']') {
if (*rcstate->regparse == '-') {
rcstate->regparse++;
if (*rcstate->regparse == ']' || *rcstate->regparse == '\0')
regc('-',rcstate);
else {
clss = UCHARAT(rcstate->regparse-2)+1;
classend = UCHARAT(rcstate->regparse);
if (clss > classend+1)
FAIL("invalid [] range");
for (; clss <= classend; clss++)
regc((char)clss,rcstate);
rcstate->regparse++;
}
} else
regc(*rcstate->regparse++,rcstate);
}
regc('\0',rcstate);
if (*rcstate->regparse != ']')
FAIL("unmatched []");
rcstate->regparse++;
*flagp |= HASWIDTH|SIMPLE;
}
break;
case '(':
ret = reg(1, &flags, rcstate);
if (ret == NULL)
return(NULL);
*flagp |= flags&(HASWIDTH|SPSTART);
break;
case '\0':
case '|':
case ')':
FAIL("internal urp"); /* Supposed to be caught earlier. */
/* NOTREACHED */
case '?':
case '+':
case '*':
FAIL("?+* follows nothing");
/* NOTREACHED */
case '\\':
if (*rcstate->regparse == '\0')
FAIL("trailing \\");
ret = regnode(EXACTLY,rcstate);
regc(*rcstate->regparse++,rcstate);
regc('\0',rcstate);
*flagp |= HASWIDTH|SIMPLE;
break;
default: {
register int len;
register char ender;
rcstate->regparse--;
len = strcspn(rcstate->regparse, META);
if (len <= 0)
FAIL("internal disaster");
ender = *(rcstate->regparse+len);
if (len > 1 && ISMULT(ender))
len--; /* Back off clear of ?+* operand. */
*flagp |= HASWIDTH;
if (len == 1)
*flagp |= SIMPLE;
ret = regnode(EXACTLY,rcstate);
while (len > 0) {
regc(*rcstate->regparse++,rcstate);
len--;
}
regc('\0',rcstate);
}
break;
}
return(ret);
}
/*
- regnode - emit a node
*/
static char * /* Location. */
regnode(op, rcstate)
int op;
struct regcomp_state *rcstate;
{
register char *ret;
register char *ptr;
ret = rcstate->regcode;
if (ret == ®dummy) {
rcstate->regsize += 3;
return(ret);
}
ptr = ret;
*ptr++ = (char)op;
*ptr++ = '\0'; /* Null "next" pointer. */
*ptr++ = '\0';
rcstate->regcode = ptr;
return(ret);
}
/*
- regc - emit (if appropriate) a byte of code
*/
static void
regc(b, rcstate)
int b;
struct regcomp_state *rcstate;
{
if (rcstate->regcode != ®dummy)
*rcstate->regcode++ = (char)b;
else
rcstate->regsize++;
}
/*
- reginsert - insert an operator in front of already-emitted operand
*
* Means relocating the operand.
*/
static void
reginsert(op, opnd, rcstate)
int op;
char *opnd;
struct regcomp_state *rcstate;
{
register char *src;
register char *dst;
register char *place;
if (rcstate->regcode == ®dummy) {
rcstate->regsize += 3;
return;
}
src = rcstate->regcode;
rcstate->regcode += 3;
dst = rcstate->regcode;
while (src > opnd)
*--dst = *--src;
place = opnd; /* Op node, where operand used to be. */
*place++ = (char)op;
*place++ = '\0';
*place = '\0';
}
/*
- regtail - set the next-pointer at the end of a node chain
*/
static void
regtail(p, val)
char *p;
char *val;
{
register char *scan;
register char *temp;
register int offset;
if (p == ®dummy)
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) = (char)((offset>>8)&0377);
*(scan+2) = (char)(offset&0377);
}
/*
- regoptail - regtail on operand of first argument; nop if operandless
*/
static void
regoptail(p, val)
char *p;
char *val;
{
/* "Operandless" and "op != BRANCH" are synonymous in practice. */
if (p == NULL || p == ®dummy || OP(p) != BRANCH)
return;
regtail(OPERAND(p), val);
}
/*
* TclRegExec and friends
*/
/*
* Global work variables for TclRegExec().
*/
struct regexec_state {
char *reginput; /* String-input pointer. */
char *regbol; /* Beginning of input, for ^ check. */
char **regstartp; /* Pointer to startp array. */
char **regendp; /* Ditto for endp. */
};
/*
* Forwards.
*/
static int regtry _ANSI_ARGS_((regexp *prog, char *string,
struct regexec_state *restate));
static int regmatch _ANSI_ARGS_((char *prog,
struct regexec_state *restate));
static int regrepeat _ANSI_ARGS_((char *p,
struct regexec_state *restate));
#ifdef DEBUG
int regnarrate = 0;
void regdump _ANSI_ARGS_((regexp *r));
static char *regprop _ANSI_ARGS_((char *op));
#endif
/*
- TclRegExec - match a regexp against a string
*/
int
TclRegExec(prog, string, start)
register regexp *prog;
register char *string;
char *start;
{
register char *s;
struct regexec_state state;
struct regexec_state *restate= &state;
/* Be paranoid... */
if (prog == NULL || string == NULL) {
TclRegError("NULL parameter");
return(0);
}
/* Check validity of program. */
if (UCHARAT(prog->program) != MAGIC) {
TclRegError("corrupted program");
return(0);
}
/* 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, prog->regmust, (size_t) prog->regmlen)
== 0)
break; /* Found it. */
s++;
}
if (s == NULL) /* Not present. */
return(0);
}
/* Mark beginning of line for ^ . */
restate->regbol = start;
/* Simplest case: anchored match need be tried only once. */
if (prog->reganch)
return(regtry(prog, string, restate));
/* 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) {
if (regtry(prog, s, restate))
return(1);
s++;
}
else
/* We don't -- general case. */
do {
if (regtry(prog, s, restate))
return(1);
} while (*s++ != '\0');
/* Failure. */
return(0);
}
/*
- regtry - try match at specific point
*/
static int /* 0 failure, 1 success */
regtry(prog, string, restate)
regexp *prog;
char *string;
struct regexec_state *restate;
{
register int i;
register char **sp;
register char **ep;
restate->reginput = string;
restate->regstartp = prog->startp;
restate->regendp = prog->endp;
sp = prog->startp;
ep = prog->endp;
for (i = NSUBEXP; i > 0; i--) {
*sp++ = NULL;
*ep++ = NULL;
}
if (regmatch(prog->program + 1,restate)) {
prog->startp[0] = string;
prog->endp[0] = restate->reginput;
return(1);
} else
return(0);
}
/*
- 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.
*/
static int /* 0 failure, 1 success */
regmatch(prog, restate)
char *prog;
struct regexec_state *restate;
{
register char *scan; /* Current node. */
char *next; /* Next 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
next = regnext(scan);
switch (OP(scan)) {
case BOL:
if (restate->reginput != restate->regbol) {
return 0;
}
break;
case EOL:
if (*restate->reginput != '\0') {
return 0;
}
break;
case ANY:
if (*restate->reginput == '\0') {
return 0;
}
restate->reginput++;
break;
case EXACTLY: {
register int len;
register char *opnd;
opnd = OPERAND(scan);
/* Inline the first character, for speed. */
if (*opnd != *restate->reginput) {
return 0 ;
}
len = strlen(opnd);
if (len > 1 && strncmp(opnd, restate->reginput, (size_t) len)
!= 0) {
return 0;
}
restate->reginput += len;
break;
}
case ANYOF:
if (*restate->reginput == '\0'
|| strchr(OPERAND(scan), *restate->reginput) == NULL) {
return 0;
}
restate->reginput++;
break;
case ANYBUT:
if (*restate->reginput == '\0'
|| strchr(OPERAND(scan), *restate->reginput) != NULL) {
return 0;
}
restate->reginput++;
break;
case NOTHING:
break;
case BACK:
break;
case OPEN+1:
case OPEN+2:
case OPEN+3:
case OPEN+4:
case OPEN+5:
case OPEN+6:
case OPEN+7:
case OPEN+8:
case OPEN+9: {
register int no;
register char *save;
doOpen:
no = OP(scan) - OPEN;
save = restate->reginput;
if (regmatch(next,restate)) {
/*
* Don't set startp if some later invocation of the
* same parentheses already has.
*/
if (restate->regstartp[no] == NULL) {
restate->regstartp[no] = save;
}
return 1;
} else {
return 0;
}
}
case CLOSE+1:
case CLOSE+2:
case CLOSE+3:
case CLOSE+4:
case CLOSE+5:
case CLOSE+6:
case CLOSE+7:
case CLOSE+8:
case CLOSE+9: {
register int no;
register char *save;
doClose:
no = OP(scan) - CLOSE;
save = restate->reginput;
if (regmatch(next,restate)) {
/*
* Don't set endp if some later
* invocation of the same parentheses
* already has.
*/
if (restate->regendp[no] == NULL)
restate->regendp[no] = save;
return 1;
} else {
return 0;
}
}
case BRANCH: {
register char *save;
if (OP(next) != BRANCH) { /* No choice. */
next = OPERAND(scan); /* Avoid recursion. */
} else {
do {
save = restate->reginput;
if (regmatch(OPERAND(scan),restate))
return(1);
restate->reginput = save;
scan = regnext(scan);
} while (scan != NULL && OP(scan) == BRANCH);
return 0;
}
break;
}
case STAR:
case PLUS: {
register char nextch;
register int no;
register char *save;
register int min;
/*
* Lookahead to avoid useless match attempts
* when we know what character comes next.
*/
nextch = '\0';
if (OP(next) == EXACTLY)
nextch = *OPERAND(next);
min = (OP(scan) == STAR) ? 0 : 1;
save = restate->reginput;
no = regrepeat(OPERAND(scan),restate);
while (no >= min) {
/* If it could work, try it. */
if (nextch == '\0' || *restate->reginput == nextch)
if (regmatch(next,restate))
return(1);
/* Couldn't or didn't -- back up. */
no--;
restate->reginput = save + no;
}
return(0);
}
case END:
return(1); /* Success! */
default:
if (OP(scan) > OPEN && OP(scan) < OPEN+NSUBEXP) {
goto doOpen;
} else if (OP(scan) > CLOSE && OP(scan) < CLOSE+NSUBEXP) {
goto doClose;
}
TclRegError("memory corruption");
return 0;
}
scan = next;
}
/*
* We get here only if there's trouble -- normally "case END" is
* the terminating point.
*/
TclRegError("corrupted pointers");
return(0);
}
/*
- regrepeat - repeatedly match something simple, report how many
*/
static int
regrepeat(p, restate)
char *p;
struct regexec_state *restate;
{
register int count = 0;
register char *scan;
register char *opnd;
scan = restate->reginput;
opnd = OPERAND(p);
switch (OP(p)) {
case ANY:
count = strlen(scan);
scan += count;
break;
case EXACTLY:
while (*opnd == *scan) {
count++;
scan++;
}
break;
case ANYOF:
while (*scan != '\0' && strchr(opnd, *scan) != NULL) {
count++;
scan++;
}
break;
case ANYBUT:
while (*scan != '\0' && strchr(opnd, *scan) == NULL) {
count++;
scan++;
}
break;
default: /* Oh dear. Called inappropriately. */
TclRegError("internal foulup");
count = 0; /* Best compromise. */
break;
}
restate->reginput = scan;
return(count);
}
/*
- regnext - dig the "next" pointer out of a node
*/
static char *
regnext(p)
register char *p;
{
register int offset;
if (p == ®dummy)
return(NULL);
offset = NEXT(p);
if (offset == 0)
return(NULL);
if (OP(p) == BACK)
return(p-offset);
else
return(p+offset);
}
#ifdef DEBUG
static char *regprop();
/*
- regdump - dump a regexp onto stdout in vaguely comprehensible form
*/
void
regdump(r)
regexp *r;
{
register char *s;
register char op = EXACTLY; /* Arbitrary non-END op. */
register char *next;
s = r->program + 1;
while (op != END) { /* While that wasn't END last time... */
op = OP(s);
printf("%2d%s", s-r->program, regprop(s)); /* Where, what. */
next = regnext(s);
if (next == NULL) /* Next ptr. */
printf("(0)");
else
printf("(%d)", (s-r->program)+(next-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 (r->regstart != '\0')
printf("start `%c' ", r->regstart);
if (r->reganch)
printf("anchored ");
if (r->regmust != NULL)
printf("must have \"%s\"", r->regmust);
printf("\n");
}
/*
- regprop - printable representation of opcode
*/
static char *
regprop(op)
char *op;
{
register char *p;
static char buf[50];
(void) 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 OPEN+1:
case OPEN+2:
case OPEN+3:
case OPEN+4:
case OPEN+5:
case OPEN+6:
case OPEN+7:
case OPEN+8:
case OPEN+9:
sprintf(buf+strlen(buf), "OPEN%d", OP(op)-OPEN);
p = NULL;
break;
case CLOSE+1:
case CLOSE+2:
case CLOSE+3:
case CLOSE+4:
case CLOSE+5:
case CLOSE+6:
case CLOSE+7:
case CLOSE+8:
case CLOSE+9:
sprintf(buf+strlen(buf), "CLOSE%d", OP(op)-CLOSE);
p = NULL;
break;
case STAR:
p = "STAR";
break;
case PLUS:
p = "PLUS";
break;
default:
if (OP(op) > OPEN && OP(op) < OPEN+NSUBEXP) {
sprintf(buf+strlen(buf), "OPEN%d", OP(op)-OPEN);
p = NULL;
break;
} else if (OP(op) > CLOSE && OP(op) < CLOSE+NSUBEXP) {
sprintf(buf+strlen(buf), "CLOSE%d", OP(op)-CLOSE);
p = NULL;
} else {
TclRegError("corrupted opcode");
}
break;
}
if (p != NULL)
(void) strcat(buf, p);
return(buf);
}
#endif
/*
* 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.
*/
#ifdef STRCSPN
/*
* strcspn - find length of initial segment of s1 consisting entirely
* of characters not from s2
*/
static int
strcspn(s1, s2)
char *s1;
char *s2;
{
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
/*
*----------------------------------------------------------------------
*
* TclRegError --
*
* This procedure is invoked by the regexp code when an error
* occurs. It saves the error message so it can be seen by the
* code that called Spencer's code.
*
* Results:
* None.
*
* Side effects:
* The value of "string" is saved in "errMsg".
*
*----------------------------------------------------------------------
*/
void
TclRegError(string)
char *string; /* Error message. */
{
errMsg = string;
}
char *
TclGetRegError()
{
return errMsg;
}