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Diffstat (limited to 'jam-files/engine/regexp.c')
| -rw-r--r-- | jam-files/engine/regexp.c | 1328 |
1 files changed, 1328 insertions, 0 deletions
diff --git a/jam-files/engine/regexp.c b/jam-files/engine/regexp.c new file mode 100644 index 00000000..30197a2f --- /dev/null +++ b/jam-files/engine/regexp.c @@ -0,0 +1,1328 @@ +/* + * 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. + *** THIS IS AN ALTERED VERSION. It was altered by John Gilmore, + *** hoptoad!gnu, on 27 Dec 1986, to add \n as an alternative to | + *** to assist in implementing egrep. + *** THIS IS AN ALTERED VERSION. It was altered by John Gilmore, + *** hoptoad!gnu, on 27 Dec 1986, to add \< and \> for word-matching + *** as in BSD grep and ex. + *** THIS IS AN ALTERED VERSION. It was altered by John Gilmore, + *** hoptoad!gnu, on 28 Dec 1986, to optimize characters quoted with \. + *** THIS IS AN ALTERED VERSION. It was altered by James A. Woods, + *** ames!jaw, on 19 June 1987, to quash a regcomp() redundancy. + *** THIS IS AN ALTERED VERSION. It was altered by Christopher Seiwald + *** seiwald@vix.com, on 28 August 1993, for use in jam. Regmagic.h + *** was moved into regexp.h, and the include of regexp.h now uses "'s + *** to avoid conflicting with the system regexp.h. Const, bless its + *** soul, was removed so it can compile everywhere. The declaration + *** of strchr() was in conflict on AIX, so it was removed (as it is + *** happily defined in string.h). + *** THIS IS AN ALTERED VERSION. It was altered by Christopher Seiwald + *** seiwald@perforce.com, on 20 January 2000, to use function prototypes. + * + * 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. + */ + + +#include "jam.h" +#include "regexp.h" +#include <stdio.h> +#include <ctype.h> +#ifndef ultrix + #include <stdlib.h> +#endif +#include <string.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 + * 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 WORDA 12 /* no Match "" at wordchar, where prev is nonword */ +#define WORDZ 13 /* no Match "" at nonwordchar, where prev is word */ +#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) + +/* + * 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) { regerror(m); return(NULL); } +#define ISMULT(c) ((c) == '*' || (c) == '+' || (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/PLUS operand. */ +#define SPSTART 04 /* Starts with * or +. */ +#define WORST 0 /* Worst case. */ + +/* + * Global work variables for regcomp(). + */ +static char *regparse; /* Input-scan pointer. */ +static int regnpar; /* () count. */ +static char regdummy; +static char *regcode; /* Code-emit pointer; ®dummy = don't. */ +static long regsize; /* Code size. */ + +/* + * Forward declarations for regcomp()'s friends. + */ +#ifndef STATIC +#define STATIC static +#endif +STATIC char *reg( int paren, int *flagp ); +STATIC char *regbranch( int *flagp ); +STATIC char *regpiece( int *flagp ); +STATIC char *regatom( int *flagp ); +STATIC char *regnode( int op ); +STATIC char *regnext( register char *p ); +STATIC void regc( int b ); +STATIC void reginsert( char op, char *opnd ); +STATIC void regtail( char *p, char *val ); +STATIC void regoptail( char *p, char *val ); +#ifdef STRCSPN +STATIC int strcspn(); +#endif + +/* + - 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( char *exp ) +{ + register regexp *r; + register char *scan; + register char *longest; + register unsigned len; + int flags; + + if (exp == NULL) + FAIL("NULL argument"); + + /* First pass: determine size, legality. */ +#ifdef notdef + if (exp[0] == '.' && exp[1] == '*') exp += 2; /* aid grep */ +#endif + regparse = (char *)exp; + regnpar = 1; + regsize = 0L; + regcode = ®dummy; + regc(MAGIC); + if (reg(0, &flags) == NULL) + return(NULL); + + /* Small enough for pointer-storage convention? */ + if (regsize >= 32767L) /* Probably could be 65535L. */ + FAIL("regexp too big"); + + /* Allocate space. */ + r = (regexp *)BJAM_MALLOC(sizeof(regexp) + (unsigned)regsize); + if (r == NULL) + FAIL("out of space"); + + /* Second pass: emit code. */ + regparse = (char *)exp; + regnpar = 1; + regcode = r->program; + regc(MAGIC); + if (reg(0, &flags) == 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 && 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( + int paren, /* Parenthesized? */ + int *flagp ) +{ + 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 (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 == '|' || *regparse == '\n') { + 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++ != ')') { + FAIL("unmatched ()"); + } else if (!paren && *regparse != '\0') { + if (*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( int *flagp ) +{ + register char *ret; + register char *chain; + register char *latest; + int flags; + + *flagp = WORST; /* Tentatively. */ + + ret = regnode(BRANCH); + chain = NULL; + while (*regparse != '\0' && *regparse != ')' && + *regparse != '\n' && *regparse != '|') { + 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. */ + (void) 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. + */ +static char * +regpiece( int *flagp ) +{ + register char *ret; + register char op; + register char *next; + int flags; + + ret = regatom(&flags); + if (ret == NULL) + return(NULL); + + op = *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); + 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)) + 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( int *flagp ) +{ + register char *ret; + int flags; + + *flagp = WORST; /* Tentatively. */ + + switch (*regparse++) { + /* FIXME: these chars only have meaning at beg/end of pat? */ + case '^': + ret = regnode(BOL); + break; + case '$': + ret = regnode(EOL); + break; + case '.': + ret = regnode(ANY); + *flagp |= HASWIDTH|SIMPLE; + break; + case '[': { + register int classr; + 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 { + classr = UCHARAT(regparse-2)+1; + classend = UCHARAT(regparse); + if (classr > classend+1) + FAIL("invalid [] range"); + for (; classr <= classend; classr++) + regc(classr); + regparse++; + } + } else + regc(*regparse++); + } + regc('\0'); + if (*regparse != ']') + FAIL("unmatched []"); + regparse++; + *flagp |= HASWIDTH|SIMPLE; + } + break; + case '(': + ret = reg(1, &flags); + if (ret == NULL) + return(NULL); + *flagp |= flags&(HASWIDTH|SPSTART); + break; + case '\0': + case '|': + case '\n': + case ')': + FAIL("internal urp"); /* Supposed to be caught earlier. */ + break; + case '?': + case '+': + case '*': + FAIL("?+* follows nothing"); + break; + case '\\': + switch (*regparse++) { + case '\0': + FAIL("trailing \\"); + break; + case '<': + ret = regnode(WORDA); + break; + case '>': + ret = regnode(WORDZ); + break; + /* FIXME: Someday handle \1, \2, ... */ + default: + /* Handle general quoted chars in exact-match routine */ + goto de_fault; + } + break; + de_fault: + default: + /* + * Encode a string of characters to be matched exactly. + * + * This is a bit tricky due to quoted chars and due to + * '*', '+', and '?' taking the SINGLE char previous + * as their operand. + * + * On entry, the char at regparse[-1] is going to go + * into the string, no matter what it is. (It could be + * following a \ if we are entered from the '\' case.) + * + * Basic idea is to pick up a good char in ch and + * examine the next char. If it's *+? then we twiddle. + * If it's \ then we frozzle. If it's other magic char + * we push ch and terminate the string. If none of the + * above, we push ch on the string and go around again. + * + * regprev is used to remember where "the current char" + * starts in the string, if due to a *+? we need to back + * up and put the current char in a separate, 1-char, string. + * When regprev is NULL, ch is the only char in the + * string; this is used in *+? handling, and in setting + * flags |= SIMPLE at the end. + */ + { + char *regprev; + register char ch; + + regparse--; /* Look at cur char */ + ret = regnode(EXACTLY); + for ( regprev = 0 ; ; ) { + ch = *regparse++; /* Get current char */ + switch (*regparse) { /* look at next one */ + + default: + regc(ch); /* Add cur to string */ + break; + + case '.': case '[': case '(': + case ')': case '|': case '\n': + case '$': case '^': + case '\0': + /* FIXME, $ and ^ should not always be magic */ + magic: + regc(ch); /* dump cur char */ + goto done; /* and we are done */ + + case '?': case '+': case '*': + if (!regprev) /* If just ch in str, */ + goto magic; /* use it */ + /* End mult-char string one early */ + regparse = regprev; /* Back up parse */ + goto done; + + case '\\': + regc(ch); /* Cur char OK */ + switch (regparse[1]){ /* Look after \ */ + case '\0': + case '<': + case '>': + /* FIXME: Someday handle \1, \2, ... */ + goto done; /* Not quoted */ + default: + /* Backup point is \, scan * point is after it. */ + regprev = regparse; + regparse++; + continue; /* NOT break; */ + } + } + regprev = regparse; /* Set backup point */ + } + done: + regc('\0'); + *flagp |= HASWIDTH; + if (!regprev) /* One char? */ + *flagp |= SIMPLE; + } + break; + } + + return(ret); +} + +/* + - regnode - emit a node + */ +static char * /* Location. */ +regnode( int 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 + */ +static void +regc( int b ) +{ + if (regcode != ®dummy) + *regcode++ = b; + else + regsize++; +} + +/* + - reginsert - insert an operator in front of already-emitted operand + * + * Means relocating the operand. + */ +static void +reginsert( + 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 + */ +static void +regtail( + 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) = (offset>>8)&0377; + *(scan+2) = offset&0377; +} + +/* + - regoptail - regtail on operand of first argument; nop if operandless + */ + +static void +regoptail( + 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); +} + +/* + * regexec and friends + */ + +/* + * Global work variables for regexec(). + */ +static char *reginput; /* String-input pointer. */ +static char *regbol; /* Beginning of input, for ^ check. */ +static char **regstartp; /* Pointer to startp array. */ +static char **regendp; /* Ditto for endp. */ + +/* + * Forwards. + */ +STATIC int regtry( regexp *prog, char *string ); +STATIC int regmatch( char *prog ); +STATIC int regrepeat( char *p ); + +#ifdef DEBUG +int regnarrate = 0; +void regdump(); +STATIC char *regprop(); +#endif + +/* + - regexec - match a regexp against a string + */ +int +regexec( + register regexp *prog, + register char *string ) +{ + register char *s; + + /* Be paranoid... */ + if (prog == NULL || string == 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 != NULL ) + { + s = (char *)string; + while ( ( s = strchr( s, prog->regmust[ 0 ] ) ) != NULL ) + { + if ( !strncmp( s, prog->regmust, prog->regmlen ) ) + break; /* Found it. */ + ++s; + } + if ( s == NULL ) /* Not present. */ + return 0; + } + + /* Mark beginning of line for ^ . */ + regbol = (char *)string; + + /* Simplest case: anchored match need be tried only once. */ + if ( prog->reganch ) + return regtry( prog, string ); + + /* Messy cases: unanchored match. */ + s = (char *)string; + if (prog->regstart != '\0') + /* We know what char it must start with. */ + while ((s = strchr(s, prog->regstart)) != NULL) { + if (regtry(prog, s)) + return(1); + s++; + } + else + /* We do not -- general case. */ + do { + if ( regtry( prog, s ) ) + return( 1 ); + } while ( *s++ != '\0' ); + + /* Failure. */ + return 0; +} + + +/* + * regtry() - try match at specific point. + */ + +static int /* 0 failure, 1 success */ +regtry( + 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++ = NULL; + *ep++ = 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 do not need to know + * whether the rest of the match failed) by a loop instead of by recursion. + */ + +static int /* 0 failure, 1 success */ +regmatch( char * prog ) +{ + 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 (reginput != regbol) + return(0); + break; + case EOL: + if (*reginput != '\0') + return(0); + break; + case WORDA: + /* Must be looking at a letter, digit, or _ */ + if ((!isalnum(*reginput)) && *reginput != '_') + return(0); + /* Prev must be BOL or nonword */ + if (reginput > regbol && + (isalnum(reginput[-1]) || reginput[-1] == '_')) + return(0); + break; + case WORDZ: + /* Must be looking at non letter, digit, or _ */ + if (isalnum(*reginput) || *reginput == '_') + return(0); + /* We don't care what the previous char was */ + 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) == NULL) + return(0); + reginput++; + break; + case ANYBUT: + if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) != 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] == 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] == 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 != 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 + */ +static int +regrepeat( 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) != NULL) { + count++; + scan++; + } + break; + case ANYBUT: + while (*scan != '\0' && strchr(opnd, *scan) == 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 + */ +static char * +regnext( 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( 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( 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; + case WORDA: + p = "WORDA"; + break; + case WORDZ: + p = "WORDZ"; + break; + default: + regerror("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( + 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 |