v09i079: newsclip 1.1, part 10 of 15

[Brad Templeton]

Posting-number: Volume 9, Issue 79
Submitted-by: brad at looking.ON.CA (Brad Templeton)
Archive-name: newsclip/part10

#! /bin/sh
# This is a shell archive.  Remove anything before this line, then unpack
# it by saving it into a file and typing "sh file".  To overwrite existing
# files, type "sh file -c".  You can also feed this as standard input via
# unshar, or by typing "sh <file", e.g..  If this archive is complete, you
# will see the following message at the end:
#		"End of archive 10 (of 15)."
# Contents:  regexp.c
# Wrapped by allbery at uunet on Tue Dec 19 20:10:03 1989
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
if test -f 'regexp.c' -a "${1}" != "-c" ; then 
  echo shar: Will not clobber existing file \"'regexp.c'\"
else
echo shar: Extracting \"'regexp.c'\" \(28251 characters\)
sed "s/^X//" >'regexp.c' <<'END_OF_FILE'
X/*
X * regcomp,  regexec, regerror and regwarning -- regsub is elsewhere
X * @(#)regexp.c	1.3 of 18 April 87
X *
X **********
X *NOTE: This version of the code has been altered for NewsClip.
X *
X *   Minor modifications to the original code have made to make
X *   memory managament and error/warning reporting conform to
X *   the rest of the newsclip runtime software.
X ***********
X *
X *	Copyright (c) 1986 by University of Toronto.
X *	Written by Henry Spencer.  Not derived from licensed software.
X *
X *	Permission is granted to anyone to use this software for any
X *	purpose on any computer system, and to redistribute it freely,
X *	subject to the following restrictions:
X *
X *	1. The author is not responsible for the consequences of use of
X *		this software, no matter how awful, even if they arise
X *		from defects in it.
X *
X *	2. The origin of this software must not be misrepresented, either
X *		by explicit claim or by omission.
X *
X *	3. Altered versions must be plainly marked as such, and must not
X *		be misrepresented as being the original software.
X *
X * Beware that some of this code is subtly aware of the way operator
X * precedence is structured in regular expressions.  Serious changes in
X * regular-expression syntax might require a total rethink.
X */
X#include <stdio.h>
X#include "rxp.h"
X#include "regmagic.h"
X
X/*
X * The "internal use only" fields in regexp.h are present to pass info from
X * compile to execute that permits the execute phase to run lots faster on
X * simple cases.  They are:
X *
X * regstart	char that must begin a match; '\0' if none obvious
X * reganch	is the match anchored (at beginning-of-line only)?
X * regmust	string (pointer into program) that match must include, or NULL
X * regmlen	length of regmust string
X *
X * Regstart and reganch permit very fast decisions on suitable starting points
X * for a match, cutting down the work a lot.  Regmust permits fast rejection
X * of lines that cannot possibly match.  The regmust tests are costly enough
X * that regcomp() supplies a regmust only if the r.e. contains something
X * potentially expensive (at present, the only such thing detected is * or +
X * at the start of the r.e., which can involve a lot of backup).  Regmlen is
X * supplied because the test in regexec() needs it and regcomp() is computing
X * it anyway.
X */
X
X/*
X * Structure for regexp "program".  This is essentially a linear encoding
X * of a nondeterministic finite-state machine (aka syntax charts or
X * "railroad normal form" in parsing technology).  Each node is an opcode
X * plus a "next" pointer, possibly plus an operand.  "Next" pointers of
X * all nodes except BRANCH implement concatenation; a "next" pointer with
X * a BRANCH on both ends of it is connecting two alternatives.  (Here we
X * have one of the subtle syntax dependencies:  an individual BRANCH (as
X * opposed to a collection of them) is never concatenated with anything
X * because of operator precedence.)  The operand of some types of node is
X * a literal string; for others, it is a node leading into a sub-FSM.  In
X * particular, the operand of a BRANCH node is the first node of the branch.
X * (NB this is *not* a tree structure:  the tail of the branch connects
X * to the thing following the set of BRANCHes.)  The opcodes are:
X */
X
X/* definition	number	opnd?	meaning */
X#define	END	0	/* no	End of program. */
X#define	BOL	1	/* no	Match "" at beginning of line. */
X#define	EOL	2	/* no	Match "" at end of line. */
X#define	ANY	3	/* no	Match any one character. */
X#define	ANYOF	4	/* str	Match any character in this string. */
X#define	ANYBUT	5	/* str	Match any character not in this string. */
X#define	BRANCH	6	/* node	Match this alternative, or the next... */
X#define	BACK	7	/* no	Match "", "next" ptr points backward. */
X#define	EXACTLY	8	/* str	Match this string. */
X#define	NOTHING	9	/* no	Match empty string. */
X#define	STAR	10	/* node	Match this (simple) thing 0 or more times. */
X#define	PLUS	11	/* node	Match this (simple) thing 1 or more times. */
X#define	OPEN	20	/* no	Mark this point in input as start of #n. */
X			/*	OPEN+1 is number 1, etc. */
X#define	CLOSE	30	/* no	Analogous to OPEN. */
X
X/*
X * Opcode notes:
X *
X * BRANCH	The set of branches constituting a single choice are hooked
X *		together with their "next" pointers, since precedence prevents
X *		anything being concatenated to any individual branch.  The
X *		"next" pointer of the last BRANCH in a choice points to the
X *		thing following the whole choice.  This is also where the
X *		final "next" pointer of each individual branch points; each
X *		branch starts with the operand node of a BRANCH node.
X *
X * BACK		Normal "next" pointers all implicitly point forward; BACK
X *		exists to make loop structures possible.
X *
X * STAR,PLUS	'?', and complex '*' and '+', are implemented as circular
X *		BRANCH structures using BACK.  Simple cases (one character
X *		per match) are implemented with STAR and PLUS for speed
X *		and to minimize recursive plunges.
X *
X * OPEN,CLOSE	...are numbered at compile time.
X */
X
X/*
X * A node is one char of opcode followed by two chars of "next" pointer.
X * "Next" pointers are stored as two 8-bit pieces, high order first.  The
X * value is a positive offset from the opcode of the node containing it.
X * An operand, if any, simply follows the node.  (Note that much of the
X * code generation knows about this implicit relationship.)
X *
X * Using two bytes for the "next" pointer is vast overkill for most things,
X * but allows patterns to get big without disasters.
X */
X#define	OP(p)	(*(p))
X#define	NEXT(p)	(((*((p)+1)&0377)<<8) + (*((p)+2)&0377))
X#define	OPERAND(p)	((p) + 3)
X
X/*
X * See regmagic.h for one further detail of program structure.
X */
X
X
X/*
X * Utility definitions.
X */
X#ifndef CHARBITS
X#define	UCHARAT(p)	((int)*(unsigned char *)(p))
X#else
X#define	UCHARAT(p)	((int)*(p)&CHARBITS)
X#endif
X
X#define	FAIL(m)	{ regwarning(m); return(NULL); }
X#define	ISMULT(c)	((c) == '*' || (c) == '+' || (c) == '?')
X#define	META	"^$.[()|?+*\\"
X
X/*
X * Flags to be passed up and down.
X */
X#define	HASWIDTH	01	/* Known never to match null string. */
X#define	SIMPLE		02	/* Simple enough to be STAR/PLUS operand. */
X#define	SPSTART		04	/* Starts with * or +. */
X#define	WORST		0	/* Worst case. */
X
X/*
X * Global work variables for regcomp().
X */
Xstatic char *regparse;		/* Input-scan pointer. */
Xstatic int regnpar;		/* () count. */
Xstatic char regdummy;
Xstatic char *regcode;		/* Code-emit pointer; &regdummy = don't. */
Xstatic long regsize;		/* Code size. */
X
X/*
X * Forward declarations for regcomp()'s friends.
X */
X#ifndef STATIC
X#define	STATIC	static
X#endif
XSTATIC char *reg();
XSTATIC char *regbranch();
XSTATIC char *regpiece();
XSTATIC char *regatom();
XSTATIC char *regnode();
XSTATIC char *regnext();
XSTATIC void regc();
XSTATIC void reginsert();
XSTATIC void regtail();
XSTATIC void regoptail();
X#ifdef STRCSPN
XSTATIC int strcspn();
X#endif
X
X#define TRE_BUF_SZ   512
X
Xchar *TREBuff = (char *) NULL;
X
X/*
X - regcomp - compile a regular expression into internal code
X *
X * We can't allocate space until we know how big the compiled form will be,
X * but we can't compile it (and thus know how big it is) until we've got a
X * place to put the code.  So we cheat:  we compile it twice, once with code
X * generation turned off and size counting turned on, and once "for real".
X * This also means that we don't allocate space until we are sure that the
X * thing really will compile successfully, and we never have to move the
X * code and thus invalidate pointers into it.  (Note that it has to be in
X * one piece because free() must be able to free it all.)
X *
X * Beware that the optimization-preparation code in here knows about some
X * of the structure of the compiled regexp.
X */
Xregexp *
Xregcomp(exp, memtype)
Xchar *exp;
Xint memtype;  /* Type of memory to use for the compiled regular expression */
X{
X	register regexp *r;
X	register char *scan;
X	register char *longest;
X	register int len;
X	int flags;
X	extern char *temp_alloc();
X	extern char *perm_alloc();
X
X	if (exp == NULL)
X		FAIL("NULL argument");
X
X	/* First pass: determine size, legality. */
X	regparse = exp;
X	regnpar = 1;
X	regsize = 0L;
X	regcode = ®dummy;
X	regc(MAGIC);
X	if (reg(0, &flags) == NULL)
X		return(NULL);
X
X	/* Small enough for pointer-storage convention? */
X	if (regsize >= 32767L)		/* Probably could be 65535L. */
X		FAIL("regexp too big");
X
X	/* Allocate space. */
X	if( memtype == RXP_MEM_PERM ) {
X		/* Allocate permanent memory for the expression. */
X		r = (regexp *)perm_alloc( sizeof(regexp) + (unsigned)regsize );
X		}
X	else if( (memtype == RXP_MEM_TEMP) ||
X		 (unsigned)regsize + sizeof(regexp) > TRE_BUF_SZ ) {
X		/* Either it won't fit in the buffer, or dynamic temporary
X		 * memory is demanded, so allocate temporary memory. */
X		r = (regexp *)temp_alloc( sizeof(regexp) + (unsigned)regsize );
X		}
X	else {
X		/* "static" memory -- memtype must be RXP_MEM_STATIC */
X		if( !TREBuff )
X			TREBuff = (char *)temp_alloc( sizeof(char)*TRE_BUF_SZ );
X		r = (regexp *) TREBuff;
X		}
X
X	if (r == NULL)
X		FAIL("out of space");
X
X	/* Second pass: emit code. */
X	regparse = exp;
X	regnpar = 1;
X	regcode = r->program;
X	regc(MAGIC);
X	if (reg(0, &flags) == NULL)
X		return(NULL);
X
X	/* Dig out information for optimizations. */
X	r->regstart = '\0';	/* Worst-case defaults. */
X	r->reganch = 0;
X	r->regmust = NULL;
X	r->regmlen = 0;
X	scan = r->program+1;			/* First BRANCH. */
X	if (OP(regnext(scan)) == END) {		/* Only one top-level choice. */
X		scan = OPERAND(scan);
X
X		/* Starting-point info. */
X		if (OP(scan) == EXACTLY)
X			r->regstart = *OPERAND(scan);
X		else if (OP(scan) == BOL)
X			r->reganch++;
X
X		/*
X		 * If there's something expensive in the r.e., find the
X		 * longest literal string that must appear and make it the
X		 * regmust.  Resolve ties in favor of later strings, since
X		 * the regstart check works with the beginning of the r.e.
X		 * and avoiding duplication strengthens checking.  Not a
X		 * strong reason, but sufficient in the absence of others.
X		 */
X		if (flags&SPSTART) {
X			longest = NULL;
X			len = 0;
X			for (; scan != NULL; scan = regnext(scan))
X				if (OP(scan) == EXACTLY && strlen(OPERAND(scan)) >= len) {
X					longest = OPERAND(scan);
X					len = strlen(OPERAND(scan));
X				}
X			r->regmust = longest;
X			r->regmlen = len;
X		}
X	}
X
X	return(r);
X}
X
X/*
X - reg - regular expression, i.e. main body or parenthesized thing
X *
X * Caller must absorb opening parenthesis.
X *
X * Combining parenthesis handling with the base level of regular expression
X * is a trifle forced, but the need to tie the tails of the branches to what
X * follows makes it hard to avoid.
X */
Xstatic char *
Xreg(paren, flagp)
Xint paren;			/* Parenthesized? */
Xint *flagp;
X{
X	register char *ret;
X	register char *br;
X	register char *ender;
X	register int parno;
X	int flags;
X
X	*flagp = HASWIDTH;	/* Tentatively. */
X
X	/* Make an OPEN node, if parenthesized. */
X	if (paren) {
X		if (regnpar >= NSUBEXP)
X			FAIL("too many ()");
X		parno = regnpar;
X		regnpar++;
X		ret = regnode(OPEN+parno);
X	} else
X		ret = NULL;
X
X	/* Pick up the branches, linking them together. */
X	br = regbranch(&flags);
X	if (br == NULL)
X		return(NULL);
X	if (ret != NULL)
X		regtail(ret, br);	/* OPEN -> first. */
X	else
X		ret = br;
X	if (!(flags&HASWIDTH))
X		*flagp &= ~HASWIDTH;
X	*flagp |= flags&SPSTART;
X	while (*regparse == '|') {
X		regparse++;
X		br = regbranch(&flags);
X		if (br == NULL)
X			return(NULL);
X		regtail(ret, br);	/* BRANCH -> BRANCH. */
X		if (!(flags&HASWIDTH))
X			*flagp &= ~HASWIDTH;
X		*flagp |= flags&SPSTART;
X	}
X
X	/* Make a closing node, and hook it on the end. */
X	ender = regnode((paren) ? CLOSE+parno : END);	
X	regtail(ret, ender);
X
X	/* Hook the tails of the branches to the closing node. */
X	for (br = ret; br != NULL; br = regnext(br))
X		regoptail(br, ender);
X
X	/* Check for proper termination. */
X	if (paren && *regparse++ != ')') {
X		FAIL("unmatched ()");
X	} else if (!paren && *regparse != '\0') {
X		if (*regparse == ')') {
X			FAIL("unmatched ()");
X		} else
X			FAIL("junk on end");	/* "Can't happen". */
X		/* NOTREACHED */
X	}
X
X	return(ret);
X}
X
X/*
X - regbranch - one alternative of an | operator
X *
X * Implements the concatenation operator.
X */
Xstatic char *
Xregbranch(flagp)
Xint *flagp;
X{
X	register char *ret;
X	register char *chain;
X	register char *latest;
X	int flags;
X
X	*flagp = WORST;		/* Tentatively. */
X
X	ret = regnode(BRANCH);
X	chain = NULL;
X	while (*regparse != '\0' && *regparse != '|' && *regparse != ')') {
X		latest = regpiece(&flags);
X		if (latest == NULL)
X			return(NULL);
X		*flagp |= flags&HASWIDTH;
X		if (chain == NULL)	/* First piece. */
X			*flagp |= flags&SPSTART;
X		else
X			regtail(chain, latest);
X		chain = latest;
X	}
X	if (chain == NULL)	/* Loop ran zero times. */
X		(void) regnode(NOTHING);
X
X	return(ret);
X}
X
X/*
X - regpiece - something followed by possible [*+?]
X *
X * Note that the branching code sequences used for ? and the general cases
X * of * and + are somewhat optimized:  they use the same NOTHING node as
X * both the endmarker for their branch list and the body of the last branch.
X * It might seem that this node could be dispensed with entirely, but the
X * endmarker role is not redundant.
X */
Xstatic char *
Xregpiece(flagp)
Xint *flagp;
X{
X	register char *ret;
X	register char op;
X	register char *next;
X	int flags;
X
X	ret = regatom(&flags);
X	if (ret == NULL)
X		return(NULL);
X
X	op = *regparse;
X	if (!ISMULT(op)) {
X		*flagp = flags;
X		return(ret);
X	}
X
X	if (!(flags&HASWIDTH) && op != '?')
X		FAIL("*+ operand could be empty");
X	*flagp = (op != '+') ? (WORST|SPSTART) : (WORST|HASWIDTH);
X
X	if (op == '*' && (flags&SIMPLE))
X		reginsert(STAR, ret);
X	else if (op == '*') {
X		/* Emit x* as (x&|), where & means "self". */
X		reginsert(BRANCH, ret);			/* Either x */
X		regoptail(ret, regnode(BACK));		/* and loop */
X		regoptail(ret, ret);			/* back */
X		regtail(ret, regnode(BRANCH));		/* or */
X		regtail(ret, regnode(NOTHING));		/* null. */
X	} else if (op == '+' && (flags&SIMPLE))
X		reginsert(PLUS, ret);
X	else if (op == '+') {
X		/* Emit x+ as x(&|), where & means "self". */
X		next = regnode(BRANCH);			/* Either */
X		regtail(ret, next);
X		regtail(regnode(BACK), ret);		/* loop back */
X		regtail(next, regnode(BRANCH));		/* or */
X		regtail(ret, regnode(NOTHING));		/* null. */
X	} else if (op == '?') {
X		/* Emit x? as (x|) */
X		reginsert(BRANCH, ret);			/* Either x */
X		regtail(ret, regnode(BRANCH));		/* or */
X		next = regnode(NOTHING);		/* null. */
X		regtail(ret, next);
X		regoptail(ret, next);
X	}
X	regparse++;
X	if (ISMULT(*regparse))
X		FAIL("nested *?+");
X
X	return(ret);
X}
X
X/*
X - regatom - the lowest level
X *
X * Optimization:  gobbles an entire sequence of ordinary characters so that
X * it can turn them into a single node, which is smaller to store and
X * faster to run.  Backslashed characters are exceptions, each becoming a
X * separate node; the code is simpler that way and it's not worth fixing.
X */
Xstatic char *
Xregatom(flagp)
Xint *flagp;
X{
X	register char *ret;
X	int flags;
X
X	*flagp = WORST;		/* Tentatively. */
X
X	switch (*regparse++) {
X	case '^':
X		ret = regnode(BOL);
X		break;
X	case '$':
X		ret = regnode(EOL);
X		break;
X	case '.':
X		ret = regnode(ANY);
X		*flagp |= HASWIDTH|SIMPLE;
X		break;
X	case '[': {
X			register int class;
X			register int classend;
X
X			if (*regparse == '^') {	/* Complement of range. */
X				ret = regnode(ANYBUT);
X				regparse++;
X			} else
X				ret = regnode(ANYOF);
X			if (*regparse == ']' || *regparse == '-')
X				regc(*regparse++);
X			while (*regparse != '\0' && *regparse != ']') {
X				if (*regparse == '-') {
X					regparse++;
X					if (*regparse == ']' || *regparse == '\0')
X						regc('-');
X					else {
X						class = UCHARAT(regparse-2)+1;
X						classend = UCHARAT(regparse);
X						if (class > classend+1)
X							FAIL("invalid [] range");
X						for (; class <= classend; class++)
X							regc(class);
X						regparse++;
X					}
X				} else
X					regc(*regparse++);
X			}
X			regc('\0');
X			if (*regparse != ']')
X				FAIL("unmatched []");
X			regparse++;
X			*flagp |= HASWIDTH|SIMPLE;
X		}
X		break;
X	case '(':
X		ret = reg(1, &flags);
X		if (ret == NULL)
X			return(NULL);
X		*flagp |= flags&(HASWIDTH|SPSTART);
X		break;
X	case '\0':
X	case '|':
X	case ')':
X		FAIL("internal urp");	/* Supposed to be caught earlier. */
X		/*NOTREACHED*/
X		break;
X	case '?':
X	case '+':
X	case '*':
X		FAIL("?+* follows nothing");
X		/*NOTREACHED*/
X		break;
X	case '\\':
X		if (*regparse == '\0')
X			FAIL("trailing \\");
X		ret = regnode(EXACTLY);
X		regc(*regparse++);
X		regc('\0');
X		*flagp |= HASWIDTH|SIMPLE;
X		break;
X	default: {
X			register int len;
X			register char ender;
X
X			regparse--;
X			len = strcspn(regparse, META);
X			if (len <= 0)
X				FAIL("internal disaster");
X			ender = *(regparse+len);
X			if (len > 1 && ISMULT(ender))
X				len--;		/* Back off clear of ?+* operand. */
X			*flagp |= HASWIDTH;
X			if (len == 1)
X				*flagp |= SIMPLE;
X			ret = regnode(EXACTLY);
X			while (len > 0) {
X				regc(*regparse++);
X				len--;
X			}
X			regc('\0');
X		}
X		break;
X	}
X
X	return(ret);
X}
X
X/*
X - regnode - emit a node
X */
Xstatic char *			/* Location. */
Xregnode(op)
Xchar op;
X{
X	register char *ret;
X	register char *ptr;
X
X	ret = regcode;
X	if (ret == &regdummy) {
X		regsize += 3;
X		return(ret);
X	}
X
X	ptr = ret;
X	*ptr++ = op;
X	*ptr++ = '\0';		/* Null "next" pointer. */
X	*ptr++ = '\0';
X	regcode = ptr;
X
X	return(ret);
X}
X
X/*
X - regc - emit (if appropriate) a byte of code
X */
Xstatic void
Xregc(b)
Xchar b;
X{
X	if (regcode != &regdummy)
X		*regcode++ = b;
X	else
X		regsize++;
X}
X
X/*
X - reginsert - insert an operator in front of already-emitted operand
X *
X * Means relocating the operand.
X */
Xstatic void
Xreginsert(op, opnd)
Xchar op;
Xchar *opnd;
X{
X	register char *src;
X	register char *dst;
X	register char *place;
X
X	if (regcode == &regdummy) {
X		regsize += 3;
X		return;
X	}
X
X	src = regcode;
X	regcode += 3;
X	dst = regcode;
X	while (src > opnd)
X		*--dst = *--src;
X
X	place = opnd;		/* Op node, where operand used to be. */
X	*place++ = op;
X	*place++ = '\0';
X	*place++ = '\0';
X}
X
X/*
X - regtail - set the next-pointer at the end of a node chain
X */
Xstatic void
Xregtail(p, val)
Xchar *p;
Xchar *val;
X{
X	register char *scan;
X	register char *temp;
X	register int offset;
X
X	if (p == &regdummy)
X		return;
X
X	/* Find last node. */
X	scan = p;
X	for (;;) {
X		temp = regnext(scan);
X		if (temp == NULL)
X			break;
X		scan = temp;
X	}
X
X	if (OP(scan) == BACK)
X		offset = scan - val;
X	else
X		offset = val - scan;
X	*(scan+1) = (offset>>8)&0377;
X	*(scan+2) = offset&0377;
X}
X
X/*
X - regoptail - regtail on operand of first argument; nop if operandless
X */
Xstatic void
Xregoptail(p, val)
Xchar *p;
Xchar *val;
X{
X	/* "Operandless" and "op != BRANCH" are synonymous in practice. */
X	if (p == NULL || p == &regdummy || OP(p) != BRANCH)
X		return;
X	regtail(OPERAND(p), val);
X}
X
X/*
X * regexec and friends
X */
X
X/*
X * Global work variables for regexec().
X */
Xstatic char *reginput;		/* String-input pointer. */
Xstatic char *regbol;		/* Beginning of input, for ^ check. */
Xstatic char **regstartp;	/* Pointer to startp array. */
Xstatic char **regendp;		/* Ditto for endp. */
X
X/*
X * Forwards.
X */
XSTATIC int regtry();
XSTATIC int regmatch();
XSTATIC int regrepeat();
X
X#ifdef DEBUG
Xint regnarrate = 0;
Xvoid regdump();
XSTATIC char *regprop();
X#endif
X
X/*
X - regexec - match a regexp against a string
X */
Xint
Xregexec(prog, string)
Xregister regexp *prog;
Xregister char *string;
X{
X	register char *s;
X	extern char *strchr();
X
X	/* Be paranoid... */
X	if( string == NULL ) {
X		regerror("NULL target parameter");
X		return(0);
X	}
X
X	if( prog == NULL ) {
X		/* Assume failure on the null program */
X		return( 0 );
X	}
X
X	/* Check validity of program. */
X	if (UCHARAT(prog->program) != MAGIC) {
X		regerror("corrupted program");
X		return(0);
X	}
X
X	/* If there is a "must appear" string, look for it. */
X	if (prog->regmust != NULL) {
X		s = string;
X		while ((s = strchr(s, prog->regmust[0])) != NULL) {
X			if (strncmp(s, prog->regmust, prog->regmlen) == 0)
X				break;	/* Found it. */
X			s++;
X		}
X		if (s == NULL)	/* Not present. */
X			return(0);
X	}
X
X	/* Mark beginning of line for ^ . */
X	regbol = string;
X
X	/* Simplest case:  anchored match need be tried only once. */
X	if (prog->reganch)
X		return(regtry(prog, string));
X
X	/* Messy cases:  unanchored match. */
X	s = string;
X	if (prog->regstart != '\0')
X		/* We know what char it must start with. */
X		while ((s = strchr(s, prog->regstart)) != NULL) {
X			if (regtry(prog, s))
X				return(1);
X			s++;
X		}
X	else
X		/* We don't -- general case. */
X		do {
X			if (regtry(prog, s))
X				return(1);
X		} while (*s++ != '\0');
X
X	/* Failure. */
X	return(0);
X}
X
X/*
X - regtry - try match at specific point
X */
Xstatic int			/* 0 failure, 1 success */
Xregtry(prog, string)
Xregexp *prog;
Xchar *string;
X{
X	register int i;
X	register char **sp;
X	register char **ep;
X
X	reginput = string;
X	regstartp = prog->startp;
X	regendp = prog->endp;
X
X	sp = prog->startp;
X	ep = prog->endp;
X	for (i = NSUBEXP; i > 0; i--) {
X		*sp++ = NULL;
X		*ep++ = NULL;
X	}
X	if (regmatch(prog->program + 1)) {
X		prog->startp[0] = string;
X		prog->endp[0] = reginput;
X		return(1);
X	} else
X		return(0);
X}
X
X/*
X - regmatch - main matching routine
X *
X * Conceptually the strategy is simple:  check to see whether the current
X * node matches, call self recursively to see whether the rest matches,
X * and then act accordingly.  In practice we make some effort to avoid
X * recursion, in particular by going through "ordinary" nodes (that don't
X * need to know whether the rest of the match failed) by a loop instead of
X * by recursion.
X */
Xstatic int			/* 0 failure, 1 success */
Xregmatch(prog)
Xchar *prog;
X{
X	register char *scan;	/* Current node. */
X	char *next;		/* Next node. */
X	extern char *strchr();
X
X	scan = prog;
X#ifdef DEBUG
X	if (scan != NULL && regnarrate)
X		fprintf(stderr, "%s(\n", regprop(scan));
X#endif
X	while (scan != NULL) {
X#ifdef DEBUG
X		if (regnarrate)
X			fprintf(stderr, "%s...\n", regprop(scan));
X#endif
X		next = regnext(scan);
X
X		switch (OP(scan)) {
X		case BOL:
X			if (reginput != regbol)
X				return(0);
X			break;
X		case EOL:
X			if (*reginput != '\0')
X				return(0);
X			break;
X		case ANY:
X			if (*reginput == '\0')
X				return(0);
X			reginput++;
X			break;
X		case EXACTLY: {
X				register int len;
X				register char *opnd;
X
X				opnd = OPERAND(scan);
X				/* Inline the first character, for speed. */
X				if (*opnd != *reginput)
X					return(0);
X				len = strlen(opnd);
X				if (len > 1 && strncmp(opnd, reginput, len) != 0)
X					return(0);
X				reginput += len;
X			}
X			break;
X		case ANYOF:
X			if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) == NULL)
X				return(0);
X			reginput++;
X			break;
X		case ANYBUT:
X			if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) != NULL)
X				return(0);
X			reginput++;
X			break;
X		case NOTHING:
X			break;
X		case BACK:
X			break;
X		case OPEN+1:
X		case OPEN+2:
X		case OPEN+3:
X		case OPEN+4:
X		case OPEN+5:
X		case OPEN+6:
X		case OPEN+7:
X		case OPEN+8:
X		case OPEN+9: {
X				register int no;
X				register char *save;
X
X				no = OP(scan) - OPEN;
X				save = reginput;
X
X				if (regmatch(next)) {
X					/*
X					 * Don't set startp if some later
X					 * invocation of the same parentheses
X					 * already has.
X					 */
X					if (regstartp[no] == NULL)
X						regstartp[no] = save;
X					return(1);
X				} else
X					return(0);
X			}
X			/*NOTREACHED*/
X			break;
X		case CLOSE+1:
X		case CLOSE+2:
X		case CLOSE+3:
X		case CLOSE+4:
X		case CLOSE+5:
X		case CLOSE+6:
X		case CLOSE+7:
X		case CLOSE+8:
X		case CLOSE+9: {
X				register int no;
X				register char *save;
X
X				no = OP(scan) - CLOSE;
X				save = reginput;
X
X				if (regmatch(next)) {
X					/*
X					 * Don't set endp if some later
X					 * invocation of the same parentheses
X					 * already has.
X					 */
X					if (regendp[no] == NULL)
X						regendp[no] = save;
X					return(1);
X				} else
X					return(0);
X			}
X			/*NOTREACHED*/
X			break;
X		case BRANCH: {
X				register char *save;
X
X				if (OP(next) != BRANCH)		/* No choice. */
X					next = OPERAND(scan);	/* Avoid recursion. */
X				else {
X					do {
X						save = reginput;
X						if (regmatch(OPERAND(scan)))
X							return(1);
X						reginput = save;
X						scan = regnext(scan);
X					} while (scan != NULL && OP(scan) == BRANCH);
X					return(0);
X					/* NOTREACHED */
X				}
X			}
X			break;
X		case STAR:
X		case PLUS: {
X				register char nextch;
X				register int no;
X				register char *save;
X				register int min;
X
X				/*
X				 * Lookahead to avoid useless match attempts
X				 * when we know what character comes next.
X				 */
X				nextch = '\0';
X				if (OP(next) == EXACTLY)
X					nextch = *OPERAND(next);
X				min = (OP(scan) == STAR) ? 0 : 1;
X				save = reginput;
X				no = regrepeat(OPERAND(scan));
X				while (no >= min) {
X					/* If it could work, try it. */
X					if (nextch == '\0' || *reginput == nextch)
X						if (regmatch(next))
X							return(1);
X					/* Couldn't or didn't -- back up. */
X					no--;
X					reginput = save + no;
X				}
X				return(0);
X			}
X			/*NOTREACHED*/
X			break;
X		case END:
X			return(1);	/* Success! */
X		default:
X			regerror("memory corruption");
X			return(0);
X		}
X
X		scan = next;
X	}
X
X	/*
X	 * We get here only if there's trouble -- normally "case END" is
X	 * the terminating point.
X	 */
X	regerror("corrupted pointers");
X	return(0);
X}
X
X/*
X - regrepeat - repeatedly match something simple, report how many
X */
Xstatic int
Xregrepeat(p)
Xchar *p;
X{
X	register int count = 0;
X	register char *scan;
X	register char *opnd;
X
X	scan = reginput;
X	opnd = OPERAND(p);
X	switch (OP(p)) {
X	case ANY:
X		count = strlen(scan);
X		scan += count;
X		break;
X	case EXACTLY:
X		while (*opnd == *scan) {
X			count++;
X			scan++;
X		}
X		break;
X	case ANYOF:
X		while (*scan != '\0' && strchr(opnd, *scan) != NULL) {
X			count++;
X			scan++;
X		}
X		break;
X	case ANYBUT:
X		while (*scan != '\0' && strchr(opnd, *scan) == NULL) {
X			count++;
X			scan++;
X		}
X		break;
X	default:		/* Oh dear.  Called inappropriately. */
X		regerror("internal foulup");
X		count = 0;	/* Best compromise. */
X		break;
X	}
X	reginput = scan;
X
X	return(count);
X}
X
X/*
X - regnext - dig the "next" pointer out of a node
X */
Xstatic char *
Xregnext(p)
Xregister char *p;
X{
X	register int offset;
X
X	if (p == &regdummy)
X		return(NULL);
X
X	offset = NEXT(p);
X	if (offset == 0)
X		return(NULL);
X
X	if (OP(p) == BACK)
X		return(p-offset);
X	else
X		return(p+offset);
X}
X
Xvoid
Xregerror(s)
Xchar *s;
X{
X	error( "fatal error in regular expression: %s", s );
X}
X
Xvoid
Xregwarning(s)
Xchar *s;
X{
X	warning(1,"error in regular expression: %s", s );
X}
X
X#ifdef DEBUG
X
XSTATIC char *regprop();
X
X/*
X - regdump - dump a regexp onto stdout in vaguely comprehensible form
X */
Xvoid
Xregdump(r)
Xregexp *r;
X{
X	register char *s;
X	register char op = EXACTLY;	/* Arbitrary non-END op. */
X	register char *next;
X	extern char *strchr();
X
X
X	s = r->program + 1;
X	while (op != END) {	/* While that wasn't END last time... */
X		op = OP(s);
X		printf("%2d%s", s-r->program, regprop(s));	/* Where, what. */
X		next = regnext(s);
X		if (next == NULL)		/* Next ptr. */
X			printf("(0)");
X		else 
X			printf("(%d)", (s-r->program)+(next-s));
X		s += 3;
X		if (op == ANYOF || op == ANYBUT || op == EXACTLY) {
X			/* Literal string, where present. */
X			while (*s != '\0') {
X				putchar(*s);
X				s++;
X			}
X			s++;
X		}
X		putchar('\n');
X	}
X
X	/* Header fields of interest. */
X	if (r->regstart != '\0')
X		printf("start `%c' ", r->regstart);
X	if (r->reganch)
X		printf("anchored ");
X	if (r->regmust != NULL)
X		printf("must have \"%s\"", r->regmust);
X	printf("\n");
X}
X
X/*
X - regprop - printable representation of opcode
X */
Xstatic char *
Xregprop(op)
Xchar *op;
X{
X	register char *p;
X	static char buf[50];
X
X	(void) strcpy(buf, ":");
X
X	switch (OP(op)) {
X	case BOL:
X		p = "BOL";
X		break;
X	case EOL:
X		p = "EOL";
X		break;
X	case ANY:
X		p = "ANY";
X		break;
X	case ANYOF:
X		p = "ANYOF";
X		break;
X	case ANYBUT:
X		p = "ANYBUT";
X		break;
X	case BRANCH:
X		p = "BRANCH";
X		break;
X	case EXACTLY:
X		p = "EXACTLY";
X		break;
X	case NOTHING:
X		p = "NOTHING";
X		break;
X	case BACK:
X		p = "BACK";
X		break;
X	case END:
X		p = "END";
X		break;
X	case OPEN+1:
X	case OPEN+2:
X	case OPEN+3:
X	case OPEN+4:
X	case OPEN+5:
X	case OPEN+6:
X	case OPEN+7:
X	case OPEN+8:
X	case OPEN+9:
X		sprintf(buf+strlen(buf), "OPEN%d", OP(op)-OPEN);
X		p = NULL;
X		break;
X	case CLOSE+1:
X	case CLOSE+2:
X	case CLOSE+3:
X	case CLOSE+4:
X	case CLOSE+5:
X	case CLOSE+6:
X	case CLOSE+7:
X	case CLOSE+8:
X	case CLOSE+9:
X		sprintf(buf+strlen(buf), "CLOSE%d", OP(op)-CLOSE);
X		p = NULL;
X		break;
X	case STAR:
X		p = "STAR";
X		break;
X	case PLUS:
X		p = "PLUS";
X		break;
X	default:
X		regerror("corrupted opcode");
X		break;
X	}
X	if (p != NULL)
X		(void) strcat(buf, p);
X	return(buf);
X}
X#endif
END_OF_FILE
if test 28251 -ne `wc -c <'regexp.c'`; then
    echo shar: \"'regexp.c'\" unpacked with wrong size!
fi
# end of 'regexp.c'
fi
echo shar: End of archive 10 \(of 15\).
cp /dev/null ark10isdone
MISSING=""
for I in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ; do
    if test ! -f ark${I}isdone ; then
	MISSING="${MISSING} ${I}"
    fi
done
if test "${MISSING}" = "" ; then
    echo You have unpacked all 15 archives.
    rm -f ark[1-9]isdone ark[1-9][0-9]isdone
else
    echo You still need to unpack the following archives:
    echo "        " ${MISSING}
fi
##  End of shell archive.
exit 0