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authorrjohnson <rjohnson>1998-03-26 14:45:59 (GMT)
committerrjohnson <rjohnson>1998-03-26 14:45:59 (GMT)
commit2b5738da524e944cda39e24c0a87b745a43bd8c3 (patch)
tree6e8c9473978f6dab66c601e911721a7bd9d70b1b /generic/regexp.c
parentc6a259aeeca4814a97cf6694814c63e74e4e18fa (diff)
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+/*
+ * 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. ***
+ *
+ * SCCS: @(#) regexp.c 1.13 97/04/29 17:49:17
+ */
+
+#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; &regdummy = 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 = &regdummy;
+ 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 == &regdummy) {
+ 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 != &regdummy)
+ *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 == &regdummy) {
+ 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 == &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) = (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 == &regdummy || 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 == &regdummy)
+ 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;
+}