Category : C++ Source Code
Archive   : JCOOL01.ZIP
Filename : REGEXP.C

 
Output of file : REGEXP.C contained in archive : JCOOL01.ZIP

//
// Copyright (C) 1991 Texas Instruments Incorporated.
//
// Permission is granted to any individual or institution to use, copy, modify,
// and distribute this software, provided that this complete copyright and
// permission notice is maintained, intact, in all copies and supporting
// documentation.
//
// Texas Instruments Incorporated provides this software "as is" without
// express or implied warranty.
//
//
// Created: MNF 06/13/89 -- Initial Design and Implementation
// Updated: MBN 09/08/89 -- Added conditional exception handling
// Updated: MBN 12/15/89 -- Sprinkled "const" qualifiers all over the place!
// Updated: MJF 03/12/90 -- Added group names to RAISE
// Updated: DLS 03/22/91 -- New lite version
//
// This file contains the implementation for the member functions of the CoolRegexp
// class. The CoolRegexp class is defined in the CoolRegexp.h header file. More
// documentation is also available in that file. A significant part of this
// file is derived directly from other work done on regular expressions. That
// part is so marked.
//

#ifndef REGEXPH // If CoolRegexp class not define
#include // Include class specification
#endif

// ~CoolRegexp -- Destructor for CoolRegexp class (not inline because it's virtual)
// Input: None
// Output: None

CoolRegexp::~CoolRegexp () {
delete [] this->program;
}


// CoolRegexp -- Copy constructor duplicates its values and state
// Input: Reference to a Regular Expression
// Output: None

CoolRegexp::CoolRegexp (const CoolRegexp& rxp) {
int ind;
this->progsize = rxp.progsize; // Copy regular expression size
this->program = new char[this->progsize]; // Allocate storage
for(ind=this->progsize; ind-- != 0;) // Copy regular expresion
this->program[ind] = rxp.program[ind];
this->startp[0] = rxp.startp[0]; // Copy pointers into last
this->endp[0] = rxp.endp[0]; // Successful "find" operation
this->regmust = rxp.regmust; // Copy field
if (rxp.regmust != NULL) {
char* dum = rxp.program;
ind = 0;
while (dum != rxp.regmust) {
++dum;
++ind;
}
this->regmust = this->program + ind;
}
this->regstart = rxp.regstart; // Copy starting index
this->reganch = rxp.reganch; // Copy remaining private data
this->regmlen = rxp.regmlen; // Copy remaining private data
}


// operator== -- Overload the equality operator for the CoolRegexp class. Two CoolRegexp
// are == if their programs are the same.
// Input: A reference to a regular expression.
// Output: Boolean TRUE/FALSE

Boolean CoolRegexp::operator== (const CoolRegexp& rxp) const {
int ind = this->progsize; // Get regular expression size
if (ind != rxp.progsize) // If different size regexp
return FALSE; // Return failure
while(ind-- != 0) // Else while still characters
if(this->program[ind] != rxp.program[ind]) // If regexp are different
return FALSE; // Return failure
return TRUE; // Else same, return success
}


// deep_equal -- Two CoolRegexp objects that are deep_equal are both == and have
// the same startp[0] and endp[0] pointers. This means that they
// have the same compiled regular expression and they last
// matched on the same identical string.
// Input: A reference to a CoolRegexp object.
// Output: Boolean TRUE/FALSE

Boolean CoolRegexp::deep_equal (const CoolRegexp& rxp) const {
int ind = this->progsize; // Get regular expression size
if (ind != rxp.progsize) // If different size regexp
return FALSE; // Return failure
while(ind-- != 0) // Else while still characters
if(this->program[ind] != rxp.program[ind]) // If regexp are different
return FALSE; // Return failure
return (this->startp[0] == rxp.startp[0] && // Else if same start/end ptrs,
this->endp[0] == rxp.endp[0]); // Return TRUE
}

// The remaining code in this file is derived from the regular expression code
// whose copyright statement appears below. It has been changed to work
// with the class concepts of C++ and COOL.

/*
* compile and find
*
* Copyright (c) 1986 by University of Toronto.
* Written by Henry Spencer. Not derived from licensed software.
*
* Permission is granted to anyone to use this software for any
* purpose on any computer system, and to redistribute it freely,
* subject to the following restrictions:
*
* 1. The author is not responsible for the consequences of use of
* this software, no matter how awful, even if they arise
* from defects in it.
*
* 2. The origin of this software must not be misrepresented, either
* by explicit claim or by omission.
*
* 3. Altered versions must be plainly marked as such, and must not
* be misrepresented as being the original software.
*
* Beware that some of this code is subtly aware of the way operator
* precedence is structured in regular expressions. Serious changes in
* regular-expression syntax might require a total rethink.
*/

/*
* The "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 compile() 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 find() needs it and compile() is computing
* it anyway.
*/

/*
* Structure for regexp "program". This is essentially a linear encoding
* of a nondeterministic finite-state machine (aka syntax charts or
* "railroad normal form" in parsing technology). Each node is an opcode
* plus a "next" pointer, possibly plus an operand. "Next" pointers of
* all nodes except BRANCH implement concatenation; a "next" pointer with
* a BRANCH on both ends of it is connecting two alternatives. (Here we
* have one of the subtle syntax dependencies: an individual BRANCH (as
* opposed to a collection of them) is never concatenated with anything
* because of operator precedence.) The operand of some types of node is
* a literal string; for others, it is a node leading into a sub-FSM. In
* particular, the operand of a BRANCH node is the first node of the branch.
* (NB this is *not* a tree structure: the tail of the branch connects
* to the thing following the set of BRANCHes.) The opcodes are:
*/

// definition number opnd? meaning
#define END 0 // no End of program.
#define BOL 1 // no Match "" at beginning of line.
#define EOL 2 // no Match "" at end of line.
#define ANY 3 // no Match any one character.
#define ANYOF 4 // str Match any character in this string.
#define ANYBUT 5 // str Match any character not in this
// string.
#define BRANCH 6 // node Match this alternative, or the
// next...
#define BACK 7 // no Match "", "next" ptr points backward.
#define EXACTLY 8 // str Match this string.
#define NOTHING 9 // no Match empty string.
#define STAR 10 // node Match this (simple) thing 0 or more
// times.
#define PLUS 11 // node Match this (simple) thing 1 or more
// times.
#define OPEN 20 // no Mark this point in input as start of
// #n.
// OPEN+1 is number 1, etc.
#define CLOSE 30 // no Analogous to OPEN.

/*
* Opcode notes:
*
* BRANCH The set of branches constituting a single choice are hooked
* together with their "next" pointers, since precedence prevents
* anything being concatenated to any individual branch. The
* "next" pointer of the last BRANCH in a choice points to the
* thing following the whole choice. This is also where the
* final "next" pointer of each individual branch points; each
* branch starts with the operand node of a BRANCH node.
*
* BACK Normal "next" pointers all implicitly point forward; BACK
* exists to make loop structures possible.
*
* STAR,PLUS '?', and complex '*' and '+', are implemented as circular
* BRANCH structures using BACK. Simple cases (one character
* per match) are implemented with STAR and PLUS for speed
* and to minimize recursive plunges.
*
* OPEN,CLOSE ...are numbered at compile time.
*/

/*
* A node is one char of opcode followed by two chars of "next" pointer.
* "Next" pointers are stored as two 8-bit pieces, high order first. The
* value is a positive offset from the opcode of the node containing it.
* An operand, if any, simply follows the node. (Note that much of the
* code generation knows about this implicit relationship.)
*
* Using two bytes for the "next" pointer is vast overkill for most things,
* but allows patterns to get big without disasters.
*/

#define OP(p) (*(p))
#define NEXT(p) (((*((p)+1)&0377)<<8) + (*((p)+2)&0377))
#define OPERAND(p) ((p) + 3)


/*
* Utility definitions.
*/
#ifndef CHARBITS
#define UCHARAT(p) ((int)*(const unsigned char*)(p))
#else
#define UCHARAT(p) ((int)*(p)&CHARBITS)
#endif

#define FAIL(m) { regerror(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.



/////////////////////////////////////////////////////////////////////////
//
// COMPILE AND ASSOCIATED FUNCTIONS
//
/////////////////////////////////////////////////////////////////////////


/*
* Global work variables for compile().
*/
static const 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 compile()'s friends.
*/
#ifndef STATIC
#define STATIC static
#endif
STATIC char* reg (int, int*);
STATIC char* regbranch (int*);
STATIC char* regpiece (int*);
STATIC char* regatom (int*);
STATIC char* regnode (char);
STATIC const char* regnext (register const char*);
STATIC char* regnext (register char*);
STATIC void regc (char);
STATIC void reginsert (char, char*);
STATIC void regtail (char*, const char*);
STATIC void regoptail (char*, const char*);

#ifdef STRCSPN
STATIC int strcspn ();
#endif


/*
- compile - 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.
*/
void CoolRegexp::compile (const char* exp) {
register const char* scan;
register const char* longest;
register int len;
int flags;

if (exp == NULL) {
//RAISE (Error, SYM(CoolRegexp), SYM(No_Expr),
printf ("CoolRegexp::compile(): No expression supplied.\n");
abort ();
}

// First pass: determine size, legality.
regparse = exp;
regnpar = 1;
regsize = 0L;
regcode = ®dummy;
regc(MAGIC);
reg(0, &flags);
this->startp[0] = this->endp[0] = this->searchstring = NULL;

// Small enough for pointer-storage convention?
if (regsize >= 32767L) { // Probably could be 65535L.
//RAISE (Error, SYM(CoolRegexp), SYM(Expr_Too_Big),
printf ("CoolRegexp::compile(): Expression too big.\n");
abort ();
}

// Allocate space.
if (this->program != NULL) delete [] this->program;
this->program = new char[regsize];
this->progsize = (int) regsize;

if (this->program == NULL) {
//RAISE (Error, SYM(CoolRegexp), SYM(Out_Of_Memory),
printf ("CoolRegexp::compile(): Out of memory.\n");
abort ();
}

// Second pass: emit code.
regparse = exp;
regnpar = 1;
regcode = this->program;
regc(MAGIC);
reg(0, &flags);

// Dig out information for optimizations.
this->regstart = '\0'; // Worst-case defaults.
this->reganch = 0;
this->regmust = NULL;
this->regmlen = 0;
scan = this->program + 1; // First BRANCH.
if (OP(regnext(scan)) == END) { // Only one top-level choice.
scan = OPERAND(scan);

// Starting-point info.
if (OP(scan) == EXACTLY)
this->regstart = *OPERAND(scan);
else if (OP(scan) == BOL)
this->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));
}
this->regmust = longest;
this->regmlen = len;
}
}
}


/*
- 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, int *flagp) {
register char* ret;
register char* br;
register char* ender;
register int parno;
int flags;

*flagp = HASWIDTH; // Tentatively.

// Make an OPEN node, if parenthesized.
if (paren) {
if (regnpar >= NSUBEXP) {
//RAISE (Error, SYM(CoolRegexp), SYM(Too_Many_Parens),
printf ("CoolRegexp::compile(): Too many parentheses.\n");
abort ();
}
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++;
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++ != ')') {
//RAISE (Error, SYM(CoolRegexp), SYM(Unmatched_Parens),
printf ("CoolRegexp::compile(): Unmatched parentheses.\n");
abort ();
}
else if (!paren && *regparse != '\0') {
if (*regparse == ')') {
//RAISE (Error, SYM(CoolRegexp), SYM(Unmatched_Parens),
printf ("CoolRegexp::compile(): Unmatched parentheses.\n");
abort ();
}
else {
//RAISE (Error, SYM(CoolRegexp), SYM(Internal_Error),
printf ("CoolRegexp::compile(): Internal error.\n");
abort ();
}
// 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 != ')') {
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.
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 != '?') {
//RAISE (Error, SYM(CoolRegexp), SYM(Empty_Operand),
printf ("CoolRegexp::compile() : *+ operand could be empty.\n");
abort ();
}
*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)) {
//RAISE (Error, SYM(CoolRegexp), SYM(Nested_Operand),
printf ("CoolRegexp::compile(): Nested *?+.\n");
abort ();
}
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++) {
case '^':
ret = regnode(BOL);
break;
case '$':
ret = regnode(EOL);
break;
case '.':
ret = regnode(ANY);
*flagp |= HASWIDTH | SIMPLE;
break;
case '[':{
register int rxpclass;
register int rxpclassend;

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 {
rxpclass = UCHARAT(regparse - 2) + 1;
rxpclassend = UCHARAT(regparse);
if (rxpclass > rxpclassend + 1) {
//RAISE (Error, SYM(CoolRegexp), SYM(Invalid_Range),
printf ("CoolRegexp::compile(): Invalid range in [].\n");
abort ();
}
for (; rxpclass <= rxpclassend; rxpclass++)
regc(rxpclass);
regparse++;
}
}
else
regc(*regparse++);
}
regc('\0');
if (*regparse != ']') {
//RAISE (Error, SYM(CoolRegexp), SYM(Unmatched_Bracket),
printf ("CoolRegexp::compile(): Unmatched [].\n");
abort ();
}
regparse++;
*flagp |= HASWIDTH | SIMPLE;
}
break;
case '(':
ret = reg(1, &flags);
if (ret == NULL)
return (NULL);
*flagp |= flags & (HASWIDTH | SPSTART);
break;
case '\0':
case '|':
case ')':
//RAISE (Error, SYM(CoolRegexp), SYM(Internal_Error),
printf ("CoolRegexp::compile(): Internal error.\n"); // Never here
abort ();
case '?':
case '+':
case '*':
//RAISE (Error, SYM(CoolRegexp), SYM(No_Operand),
printf ("CoolRegexp::compile(): ?+* follows nothing.\n");
abort ();
case '\\':
if (*regparse == '\0') {
//RAISE (Error, SYM(CoolRegexp), SYM(Trailing_Backslash),
printf ("CoolRegexp::compile(): Trailing backslash.\n");
abort ();
}
ret = regnode(EXACTLY);
regc(*regparse++);
regc('\0');
*flagp |= HASWIDTH | SIMPLE;
break;
default:{
register int len;
register char ender;

regparse--;
len = strcspn(regparse, META);
if (len <= 0) {
//RAISE (Error, SYM(CoolRegexp), SYM(Internal_Error),
printf ("CoolRegexp::compile(): Internal error.\n");
abort ();
}
ender = *(regparse + len);
if (len > 1 && ISMULT(ender))
len--; // Back off clear of ?+* operand.
*flagp |= HASWIDTH;
if (len == 1)
*flagp |= SIMPLE;
ret = regnode(EXACTLY);
while (len > 0) {
regc(*regparse++);
len--;
}
regc('\0');
}
break;
}
return (ret);
}


/*
- regnode - emit a node
Location.
*/
static char* regnode (char op) {
register char* ret;
register char* ptr;

ret = regcode;
if (ret == ®dummy) {
regsize += 3;
return (ret);
}

ptr = ret;
*ptr++ = op;
*ptr++ = '\0'; // Null "next" pointer.
*ptr++ = '\0';
regcode = ptr;

return (ret);
}


/*
- regc - emit (if appropriate) a byte of code
*/
static void regc (char 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, const 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 = (const char*)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, const char* val) {
// "Operandless" and "op != BRANCH" are synonymous in practice.
if (p == NULL || p == ®dummy || OP(p) != BRANCH)
return;
regtail(OPERAND(p), val);
}



////////////////////////////////////////////////////////////////////////
//
// find and friends
//
////////////////////////////////////////////////////////////////////////


/*
* Global work variables for find().
*/
static const char* reginput; // String-input pointer.
static const char* regbol; // Beginning of input, for ^ check.
static const char* *regstartp; // Pointer to startp array.
static const char* *regendp; // Ditto for endp.

/*
* Forwards.
*/
STATIC int regtry (const char*, const char*[NSUBEXP],

const char*[NSUBEXP], const char*);
STATIC int regmatch (const char*);
STATIC int regrepeat (const char*);

#ifdef DEBUG
int regnarrate = 0;
void regdump ();
STATIC char* regprop ();
#endif


/*
- find - match a regexpr against a string
*/
Boolean CoolRegexp::find (const char* string) {
register const char* s;

this->searchstring = string;

// Check validity of program.
if (UCHARAT(this->program) != MAGIC) {
//RAISE (Error, SYM(CoolRegexp), SYM(Internal_Error),
printf ("CoolRegexp::find(): Compiled regular expression corrupted.\n");
abort ();
}

// If there is a "must appear" string, look for it.
if (this->regmust != NULL) {
s = string;
while ((s = strchr(s, this->regmust[0])) != NULL) {
if (strncmp(s, this->regmust, this->regmlen) == 0)
break; // Found it.
s++;
}
if (s == NULL) // Not present.
return (0);
}

// Mark beginning of line for ^ .
regbol = string;

// Simplest case: anchored match need be tried only once.
if (this->reganch)
return (regtry(string, this->startp, this->endp, this->program));

// Messy cases: unanchored match.
s = string;
if (this->regstart != '\0')
// We know what char it must start with.
while ((s = strchr(s, this->regstart)) != NULL) {
if (regtry(s, this->startp, this->endp, this->program))
return (1);
s++;

}
else
// We don't -- general case.
do {
if (regtry(s, this->startp, this->endp, this->program))
return (1);
} while (*s++ != '\0');

// Failure.
return (0);
}


/*
- regtry - try match at specific point
0 failure, 1 success
*/
static int regtry (const char* string, const char* *start,
const char* *end, const char* prog) {
register int i;
register const char* *sp1;
register const char* *ep;

reginput = string;
regstartp = start;
regendp = end;

sp1 = start;
ep = end;

for (i = NSUBEXP; i > 0; i--) {
*sp1++ = NULL;
*ep++ = NULL;
}
if (regmatch(prog + 1)) {
start[0] = string;
end[0] = reginput;
return (1);
}
else
return (0);
}


/*
- regmatch - main matching routine
*
* Conceptually the strategy is simple: check to see whether the current
* node matches, call self recursively to see whether the rest matches,
* and then act accordingly. In practice we make some effort to avoid
* recursion, in particular by going through "ordinary" nodes (that don't
* need to know whether the rest of the match failed) by a loop instead of
* by recursion.
* 0 failure, 1 success
*/
static int regmatch (const char* prog) {
register const char* scan; // Current node.
const char* next; // Next node.

scan = prog;

while (scan != NULL) {

next = regnext(scan);

switch (OP(scan)) {
case BOL:
if (reginput != regbol)
return (0);
break;
case EOL:
if (*reginput != '\0')
return (0);
break;
case ANY:
if (*reginput == '\0')
return (0);
reginput++;
break;
case EXACTLY:{
register int len;
register const 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 const 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 const 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 const 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 const char* save;
register int min_no;

//
// Lookahead to avoid useless match attempts when we know
// what character comes next.
//
nextch = '\0';
if (OP(next) == EXACTLY)
nextch = *OPERAND(next);
min_no = (OP(scan) == STAR) ? 0 : 1;
save = reginput;
no = regrepeat(OPERAND(scan));
while (no >= min_no) {
// 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!

default:
//RAISE (Error, SYM(CoolRegexp), SYM(Internal_Error),
printf ("CoolRegexp::find(): Internal error -- memory corrupted.\n");
abort ();
}
scan = next;
}

//
// We get here only if there's trouble -- normally "case END" is the
// terminating point.
//
//RAISE (Error, SYM(CoolRegexp), SYM(Internal_Error),
printf ("CoolRegexp::find(): Internal error -- corrupted pointers.\n");
abort ();
return (0);
}


/*
- regrepeat - repeatedly match something simple, report how many
*/
static int regrepeat (const char* p) {
register int count = 0;
register const char* scan;
register const 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.
//RAISE (Error, SYM(CoolRegexp), SYM(Internal_Error),
printf ("CoolRegexp::find(): Internal error.\n");
abort ();
}
reginput = scan;
return (count);
}


/*
- regnext - dig the "next" pointer out of a node
*/
static const char* regnext (register const 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);
}


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);
}