Minix1.5/lib/other/regexp.c
/* regcomp and regexec -- regsub and regerror are 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.
*
* The third parameter to regexec was added by Martin C. Atkins.
* Andy Tanenbaum also made some changes.
*/
#include <minix/const.h>
#include <stdlib.h>
#include <string.h>
#include <regexp.h>
#include <stdio.h>
/* The first byte of the regexp internal "program" is actually this magic
* number; the start node begins in the second byte.
*/
#define MAGIC 0234
/* 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 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 regexec() needs it and 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 "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 30 /* 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)
/* Utility definitions.
*/
#ifndef CHARBITS
#define UCHARAT(p) ((int)*(unsigned char *)(p))
#else
#define UCHARAT(p) ((int)*(p)&CHARBITS)
#endif
#define CFAIL(m) { regerror(m); return((char *)NULL); }
#define RFAIL(m) { regerror(m); return((regexp *)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 regcomp().
*/
PRIVATE char *regparse; /* Input-scan pointer. */
PRIVATE int regnpar; /* () count. */
PRIVATE char regdummy;
PRIVATE char *regcode; /* Code-emit pointer; ®dummy = don't. */
PRIVATE long regsize; /* Code size. */
/* Forward declarations for regcomp()'s friends.
*/
#ifndef STATIC
#define STATIC PRIVATE
#endif
STATIC _PROTOTYPE( char *reg, (int paren, int *flagp) );
STATIC _PROTOTYPE( char *regbranch, (int *flagp) );
STATIC _PROTOTYPE( char *regpiece, (int *flagp) );
STATIC _PROTOTYPE( char *regatom, (int *flagp) );
STATIC _PROTOTYPE( char *regnode, (int op) );
STATIC _PROTOTYPE( char *regnext, (char *p) );
STATIC _PROTOTYPE( void regc, (int b) );
STATIC _PROTOTYPE( void reginsert, (int op, char *opnd) );
STATIC _PROTOTYPE( void regtail, (char *p, char *val) );
STATIC _PROTOTYPE( void regoptail, (char *p, char *val) );
/*
- regcomp - 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 *regcomp(exp)
char *exp;
{
register regexp *r;
register char *scan;
register char *longest;
register int len;
int flags;
if (exp == (char *)NULL) RFAIL("NULL argument");
/* First pass: determine size, legality. */
regparse = exp;
regnpar = 1;
regsize = 0L;
regcode = ®dummy;
regc(MAGIC);
if (reg(0, &flags) == (char *)NULL) return((regexp *)NULL);
/* Small enough for pointer-storage convention? */
if (regsize >= 32767L) /* Probably could be 65535L. */
RFAIL("regexp too big");
/* Allocate space. */
r = (regexp *) malloc(sizeof(regexp) + (unsigned) regsize);
if (r == (regexp *)NULL) RFAIL("out of space");
/* Second pass: emit code. */
regparse = exp;
regnpar = 1;
regcode = r->program;
regc(MAGIC);
if (reg(0, &flags) == (char *)NULL) return((regexp *)NULL);
/* Dig out information for optimizations. */
r->regstart = '\0'; /* Worst-case defaults. */
r->reganch = 0;
r->regmust = (char *)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 = (char *)NULL;
len = 0;
for (; scan != (char *)NULL; scan = regnext(scan))
if (OP(scan) == EXACTLY && 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.
*/
PRIVATE char *reg(paren, flagp)
int paren; /* Parenthesized? */
int *flagp;
{
register char *ret;
register char *br;
register char *ender;
register int parno;
int flags;
*flagp = HASWIDTH; /* Tentatively. */
/* Make an OPEN node, if parenthesized. */
if (paren) {
if (regnpar >= NSUBEXP) CFAIL("too many ()");
parno = regnpar;
regnpar++;
ret = regnode(OPEN + parno);
} else {
parno = 0; /* not actually used, keep compiler quiet */
ret = (char *)NULL;
}
/* Pick up the branches, linking them together. */
br = regbranch(&flags);
if (br == (char *)NULL) return((char *)NULL);
if (ret != (char *)NULL)
regtail(ret, br); /* OPEN -> first. */
else
ret = br;
if (!(flags & HASWIDTH)) *flagp &= ~HASWIDTH;
*flagp |= flags & SPSTART;
while (*regparse == '|') {
regparse++;
br = regbranch(&flags);
if (br == (char *)NULL) return((char *)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 != (char *)NULL; br = regnext(br)) regoptail(br, ender);
/* Check for proper termination. */
if (paren && *regparse++ != ')') {
CFAIL("unmatched ()");
} else if (!paren && *regparse != '\0') {
if (*regparse == ')') {
CFAIL("unmatched ()");
} else
CFAIL("junk on end"); /* "Can't happen". */
/* NOTREACHED */
}
return(ret);
}
/*
- regbranch - one alternative of an | operator
*
* Implements the concatenation operator.
*/
PRIVATE char *regbranch(flagp)
int *flagp;
{
register char *ret;
register char *chain;
register char *latest;
int flags;
*flagp = WORST; /* Tentatively. */
ret = regnode(BRANCH);
chain = (char *)NULL;
while (*regparse != '\0' && *regparse != '|' && *regparse != ')') {
latest = regpiece(&flags);
if (latest == (char *)NULL) return((char *)NULL);
*flagp |= flags & HASWIDTH;
if (chain == (char *)NULL) /* First piece. */
*flagp |= flags & SPSTART;
else
regtail(chain, latest);
chain = latest;
}
if (chain == (char *)NULL) /* Loop ran zero times. */
regnode(NOTHING);
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.
*/
PRIVATE char *regpiece(flagp)
int *flagp;
{
register char *ret;
register char op;
register char *next;
int flags;
ret = regatom(&flags);
if (ret == (char *)NULL) return((char *)NULL);
op = *regparse;
if (!ISMULT(op)) {
*flagp = flags;
return(ret);
}
if (!(flags & HASWIDTH) && op != '?') CFAIL("*+ operand could be empty");
*flagp = (op != '+') ? (WORST | SPSTART) : (WORST | HASWIDTH);
if (op == '*' && (flags & SIMPLE))
reginsert(STAR, ret);
else if (op == '*') {
/* 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 == '+' && (flags & SIMPLE))
reginsert(PLUS, ret);
else if (op == '+') {
/* Emit x+ as x(&|), where & means "self". */
next = regnode(BRANCH); /* Either */
regtail(ret, next);
regtail(regnode(BACK), ret); /* loop back */
regtail(next, regnode(BRANCH)); /* or */
regtail(ret, regnode(NOTHING)); /* null. */
} else if (op == '?') {
/* Emit x? as (x|) */
reginsert(BRANCH, ret); /* Either x */
regtail(ret, regnode(BRANCH)); /* or */
next = regnode(NOTHING);/* null. */
regtail(ret, next);
regoptail(ret, next);
}
regparse++;
if (ISMULT(*regparse)) CFAIL("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.
*/
PRIVATE char *regatom(flagp)
int *flagp;
{
register char *ret;
int flags;
*flagp = WORST; /* Tentatively. */
switch (*regparse++) {
case '^': ret = regnode(BOL); break;
case '$': ret = regnode(EOL); break;
case '.':
ret = regnode(ANY);
*flagp |= HASWIDTH | SIMPLE;
break;
case '[':{
register int class;
register int classend;
if (*regparse == '^') { /* Complement of range. */
ret = regnode(ANYBUT);
regparse++;
} else
ret = regnode(ANYOF);
if (*regparse == ']' || *regparse == '-') regc(*regparse++);
while (*regparse != '\0' && *regparse != ']') {
if (*regparse == '-') {
regparse++;
if (*regparse == ']' || *regparse == '\0')
regc('-');
else {
class = UCHARAT(regparse - 2) + 1;
classend = UCHARAT(regparse);
if (class > classend + 1)
CFAIL("invalid [] range");
for (; class <= classend; class++)
regc(class);
regparse++;
}
} else
regc(*regparse++);
}
regc('\0');
if (*regparse != ']') CFAIL("unmatched []");
regparse++;
*flagp |= HASWIDTH | SIMPLE;
}
break;
case '(':
ret = reg(1, &flags);
if (ret == (char *)NULL) return((char *)NULL);
*flagp |= flags & (HASWIDTH | SPSTART);
break;
case '\0':
case '|':
case ')':
CFAIL("internal urp"); /* Supposed to be caught earlier. */
break;
case '?':
case '+':
case '*': CFAIL("?+* follows nothing"); break;
case '\\':
if (*regparse == '\0') CFAIL("trailing \\");
ret = regnode(EXACTLY);
regc(*regparse++);
regc('\0');
*flagp |= HASWIDTH | SIMPLE;
break;
default:{
register int len;
register char ender;
regparse--;
len = strcspn(regparse, META);
if (len <= 0) CFAIL("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);
}
/*
- regnode - emit a node
*/
PRIVATE char *regnode(op)
char op;
{
register char *ret;
register char *ptr;
ret = regcode;
if (ret == ®dummy) {
regsize += 3;
return(ret);
}
ptr = ret;
*ptr++ = op;
*ptr++ = '\0'; /* Null "next" pointer. */
*ptr++ = '\0';
regcode = ptr;
return(ret);
}
/*
- regc - emit (if appropriate) a byte of code
*/
PRIVATE void regc(b)
char b;
{
if (regcode != ®dummy)
*regcode++ = b;
else
regsize++;
}
/*
- reginsert - insert an operator in front of already-emitted operand
*
* Means relocating the operand.
*/
PRIVATE void reginsert(op, opnd)
char op;
char *opnd;
{
register char *src;
register char *dst;
register char *place;
if (regcode == ®dummy) {
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';
}
/*
- regtail - set the next-pointer at the end of a node chain
*/
PRIVATE 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 == (char *)NULL) break;
scan = temp;
}
if (OP(scan) == BACK)
offset = scan - val;
else
offset = val - scan;
*(scan + 1) = (offset >> 8) & 0377;
*(scan + 2) = offset & 0377;
}
/*
- regoptail - regtail on operand of first argument; nop if operandless
*/
PRIVATE void regoptail(p, val)
char *p;
char *val;
{
/* "Operandless" and "op != BRANCH" are synonymous in practice. */
if (p == (char *)NULL || p == ®dummy || OP(p) != BRANCH) return;
regtail(OPERAND(p), val);
}
/* regexec and friends
*/
/* Global work variables for regexec().
*/
PRIVATE char *reginput; /* String-input pointer. */
PRIVATE char *regbol; /* Beginning of input, for ^ check. */
PRIVATE char **regstartp; /* Pointer to startp array. */
PRIVATE char **regendp; /* Ditto for endp. */
/* Forwards.
*/
STATIC _PROTOTYPE( int regtry, (regexp *prog, char *string) );
STATIC _PROTOTYPE( int regmatch, (char *prog) );
STATIC _PROTOTYPE( int regrepeat, (char *p) );
#ifdef DEBUG
int regnarrate = 0;
void regdump();
STATIC _PROTOTYPE( char *regprop, (char *op) );
#endif
/*
- regexec - match a regexp against a string
*/
int regexec(prog, string, bolflag)
register regexp *prog;
register char *string;
int bolflag;
{
register char *s;
/* Be paranoid... */
if (prog == (regexp *)NULL || string == (char *)NULL) {
regerror("NULL parameter");
return(0);
}
/* Check validity of program. */
if (UCHARAT(prog->program) != MAGIC) {
regerror("corrupted program");
return(0);
}
/* If there is a "must appear" string, look for it. */
if (prog->regmust != (char *)NULL) {
s = string;
while ((s = strchr(s, prog->regmust[0])) != (char *)NULL) {
if (strncmp(s, prog->regmust, prog->regmlen) == 0)
break; /* Found it. */
s++;
}
if (s == (char *)NULL) /* Not present. */
return(0);
}
/* Mark beginning of line for ^ . */
if (bolflag)
regbol = string;
else
regbol = (char *)NULL;
/* 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)) != (char *)NULL) {
if (regtry(prog, s)) return(1);
s++;
}
else
/* We don't -- general case. */
do {
if (regtry(prog, s)) return(1);
} while (*s++ != '\0');
/* Failure. */
return(0);
}
/*
- regtry - try match at specific point
*/
PRIVATE int regtry(prog, string) /* 0 failure, 1 success */
regexp *prog;
char *string;
{
register int i;
register char **sp;
register char **ep;
reginput = string;
regstartp = prog->startp;
regendp = prog->endp;
sp = prog->startp;
ep = prog->endp;
for (i = NSUBEXP; i > 0; i--) {
*sp++ = (char *)NULL;
*ep++ = (char *)NULL;
}
if (regmatch(prog->program + 1)) {
prog->startp[0] = string;
prog->endp[0] = 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.
*/
PRIVATE int regmatch(prog) /* 0 failure, 1 success */
char *prog;
{
register char *scan; /* Current node. */
char *next; /* Next node. */
scan = prog;
#ifdef DEBUG
if (scan != (char *)NULL && regnarrate) fprintf(stderr, "%s(\n", regprop(scan));
#endif
while (scan != (char *)NULL) {
#ifdef DEBUG
if (regnarrate) fprintf(stderr, "%s...\n", regprop(scan));
#endif
next = regnext(scan);
switch (OP(scan)) {
case BOL:
if (reginput != regbol) return(0);
break;
case EOL:
if (*reginput != '\0') return(0);
break;
case ANY:
if (*reginput == '\0') return(0);
reginput++;
break;
case EXACTLY:{
register int len;
register char *opnd;
opnd = OPERAND(scan);
/* Inline the first character, for speed. */
if (*opnd != *reginput) return(0);
len = strlen(opnd);
if (len > 1 && strncmp(opnd, reginput, len) != 0)
return(0);
reginput += len;
}
break;
case ANYOF:
if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) == (char *)NULL)
return(0);
reginput++;
break;
case ANYBUT:
if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) != (char *)NULL)
return(0);
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;
no = OP(scan) - OPEN;
save = reginput;
if (regmatch(next)) {
/* Don't set startp if some later
* invocation of the same parentheses
* already has. */
if (regstartp[no] == (char *)NULL)
regstartp[no] = save;
return(1);
} else
return(0);
}
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:{
register int no;
register char *save;
no = OP(scan) - CLOSE;
save = reginput;
if (regmatch(next)) {
/* Don't set endp if some later
* invocation of the same parentheses
* already has. */
if (regendp[no] == (char *)NULL) regendp[no] = save;
return(1);
} else
return(0);
}
break;
case BRANCH:{
register char *save;
if (OP(next) != BRANCH) /* No choice. */
next = OPERAND(scan); /* Avoid recursion. */
else {
do {
save = reginput;
if (regmatch(OPERAND(scan)))
return(1);
reginput = save;
scan = regnext(scan);
} while (scan != (char *)NULL && OP(scan) == BRANCH);
return(0);
/* NOTREACHED */
}
}
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 = reginput;
no = regrepeat(OPERAND(scan));
while (no >= min) {
/* If it could work, try it. */
if (nextch == '\0' || *reginput == nextch)
if (regmatch(next)) return(1);
/* Couldn't or didn't -- back up. */
no--;
reginput = save + no;
}
return(0);
}
break;
case END:
return(1); /* Success! */
break;
default:
regerror("memory corruption");
return(0);
break;
}
scan = next;
}
/* We get here only if there's trouble -- normally "case END" is the
* terminating point. */
regerror("corrupted pointers");
return(0);
}
/*
- regrepeat - repeatedly match something simple, report how many
*/
PRIVATE int regrepeat(p)
char *p;
{
register int count = 0;
register char *scan;
register char *opnd;
scan = 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) != (char *)NULL) {
count++;
scan++;
}
break;
case ANYBUT:
while (*scan != '\0' && strchr(opnd, *scan) == (char *)NULL) {
count++;
scan++;
}
break;
default: /* Oh dear. Called inappropriately. */
regerror("internal foulup");
count = 0; /* Best compromise. */
break;
}
reginput = scan;
return(count);
}
/*
- regnext - dig the "next" pointer out of a node
*/
PRIVATE char *regnext(p)
register char *p;
{
register int offset;
if (p == ®dummy) return((char *)NULL);
offset = NEXT(p);
if (offset == 0) return((char *)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", (int) (s - r->program), regprop(s)); /* Where, what. */
next = regnext(s);
if (next == (char *)NULL) /* Next ptr. */
printf("(0)");
else
printf("(%d)", (int) (s - r->program) + (int) (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 != (char *)NULL) printf("must have \"%s\"", r->regmust);
printf("\n");
}
/*
- regprop - printable representation of opcode
*/
PRIVATE char *regprop(op)
char *op;
{
register char *p;
PRIVATE 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 = (char *)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 = (char *)NULL;
break;
case STAR: p = "STAR"; break;
case PLUS: p = "PLUS"; break;
default: regerror("corrupted opcode"); p = (char *) NULL; break;
}
if (p != (char *)NULL) (void) strcat(buf, p);
return(buf);
}
#endif