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b.c
1527 lines (1392 loc) · 36 KB
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b.c
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/****************************************************************
Copyright (C) Lucent Technologies 1997
All Rights Reserved
Permission to use, copy, modify, and distribute this software and
its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in all
copies and that both that the copyright notice and this
permission notice and warranty disclaimer appear in supporting
documentation, and that the name Lucent Technologies or any of
its entities not be used in advertising or publicity pertaining
to distribution of the software without specific, written prior
permission.
LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.
****************************************************************/
/* lasciate ogne speranza, voi ch'intrate. */
#define DEBUG
#include <ctype.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "awk.h"
#include "awkgram.tab.h"
#define MAXLIN 22
#define type(v) (v)->nobj /* badly overloaded here */
#define info(v) (v)->ntype /* badly overloaded here */
#define left(v) (v)->narg[0]
#define right(v) (v)->narg[1]
#define parent(v) (v)->nnext
#define LEAF case CCL: case NCCL: case CHAR: case DOT: case FINAL: case ALL:
#define ELEAF case EMPTYRE: /* empty string in regexp */
#define UNARY case STAR: case PLUS: case QUEST:
/* encoding in tree Nodes:
leaf (CCL, NCCL, CHAR, DOT, FINAL, ALL, EMPTYRE):
left is index, right contains value or pointer to value
unary (STAR, PLUS, QUEST): left is child, right is null
binary (CAT, OR): left and right are children
parent contains pointer to parent
*/
int *setvec;
int *tmpset;
int maxsetvec = 0;
int rtok; /* next token in current re */
int rlxval;
static const uschar *rlxstr;
static const uschar *prestr; /* current position in current re */
static const uschar *lastre; /* origin of last re */
static const uschar *lastatom; /* origin of last Atom */
static const uschar *starttok;
static const uschar *basestr; /* starts with original, replaced during
repetition processing */
static const uschar *firstbasestr;
static int setcnt;
static int poscnt;
const char *patbeg;
int patlen;
#define NFA 128 /* cache this many dynamic fa's */
fa *fatab[NFA];
int nfatab = 0; /* entries in fatab */
extern int u8_nextlen(const char *s);
/* utf-8 mechanism:
For most of Awk, utf-8 strings just "work", since they look like
null-terminated sequences of 8-bit bytes.
Functions like length(), index(), and substr() have to operate
in units of utf-8 characters. The u8_* functions in run.c
handle this.
Regular expressions are more complicated, since the basic
mechanism of the goto table used 8-bit byte indices into the
gototab entries to compute the next state. Unicode is a lot
bigger, so the gototab entries are now structs with a character
and a next state, and there is a linear search of the characters
to find the state. (Yes, this is slower, by a significant
amount. Tough.)
Throughout the RE mechanism in b.c, utf-8 characters are
converted to their utf-32 value. This mostly shows up in
cclenter, which expands character class ranges like a-z and now
alpha-omega. The size of a gototab array is still about 256.
This should be dynamic, but for now things work ok for a single
code page of Unicode, which is the most likely case.
The code changes are localized in run.c and b.c. I have added a
handful of functions to somewhat better hide the implementation,
but a lot more could be done.
*/
static int get_gototab(fa*, int, int);
static int set_gototab(fa*, int, int, int);
extern int u8_rune(int *, const uschar *);
static int *
intalloc(size_t n, const char *f)
{
int *p = (int *) calloc(n, sizeof(int));
if (p == NULL)
overflo(f);
return p;
}
static void
resizesetvec(const char *f)
{
if (maxsetvec == 0)
maxsetvec = MAXLIN;
else
maxsetvec *= 4;
setvec = (int *) realloc(setvec, maxsetvec * sizeof(*setvec));
tmpset = (int *) realloc(tmpset, maxsetvec * sizeof(*tmpset));
if (setvec == NULL || tmpset == NULL)
overflo(f);
}
static void
resize_state(fa *f, int state)
{
gtt **p;
uschar *p2;
int **p3;
int i, new_count;
if (++state < f->state_count)
return;
new_count = state + 10; /* needs to be tuned */
p = (gtt **) realloc(f->gototab, new_count * sizeof(f->gototab[0]));
if (p == NULL)
goto out;
f->gototab = p;
p2 = (uschar *) realloc(f->out, new_count * sizeof(f->out[0]));
if (p2 == NULL)
goto out;
f->out = p2;
p3 = (int **) realloc(f->posns, new_count * sizeof(f->posns[0]));
if (p3 == NULL)
goto out;
f->posns = p3;
for (i = f->state_count; i < new_count; ++i) {
f->gototab[i] = (gtt *) calloc(NCHARS, sizeof(**f->gototab));
if (f->gototab[i] == NULL)
goto out;
f->out[i] = 0;
f->posns[i] = NULL;
}
f->gototab_len = NCHARS; /* should be variable, growable */
f->state_count = new_count;
return;
out:
overflo(__func__);
}
fa *makedfa(const char *s, bool anchor) /* returns dfa for reg expr s */
{
int i, use, nuse;
fa *pfa;
static int now = 1;
if (setvec == NULL) { /* first time through any RE */
resizesetvec(__func__);
}
if (compile_time != RUNNING) /* a constant for sure */
return mkdfa(s, anchor);
for (i = 0; i < nfatab; i++) /* is it there already? */
if (fatab[i]->anchor == anchor
&& strcmp((const char *) fatab[i]->restr, s) == 0) {
fatab[i]->use = now++;
return fatab[i];
}
pfa = mkdfa(s, anchor);
if (nfatab < NFA) { /* room for another */
fatab[nfatab] = pfa;
fatab[nfatab]->use = now++;
nfatab++;
return pfa;
}
use = fatab[0]->use; /* replace least-recently used */
nuse = 0;
for (i = 1; i < nfatab; i++)
if (fatab[i]->use < use) {
use = fatab[i]->use;
nuse = i;
}
freefa(fatab[nuse]);
fatab[nuse] = pfa;
pfa->use = now++;
return pfa;
}
fa *mkdfa(const char *s, bool anchor) /* does the real work of making a dfa */
/* anchor = true for anchored matches, else false */
{
Node *p, *p1;
fa *f;
firstbasestr = (const uschar *) s;
basestr = firstbasestr;
p = reparse(s);
p1 = op2(CAT, op2(STAR, op2(ALL, NIL, NIL), NIL), p);
/* put ALL STAR in front of reg. exp. */
p1 = op2(CAT, p1, op2(FINAL, NIL, NIL));
/* put FINAL after reg. exp. */
poscnt = 0;
penter(p1); /* enter parent pointers and leaf indices */
if ((f = (fa *) calloc(1, sizeof(fa) + poscnt * sizeof(rrow))) == NULL)
overflo(__func__);
f->accept = poscnt-1; /* penter has computed number of positions in re */
cfoll(f, p1); /* set up follow sets */
freetr(p1);
resize_state(f, 1);
f->posns[0] = intalloc(*(f->re[0].lfollow), __func__);
f->posns[1] = intalloc(1, __func__);
*f->posns[1] = 0;
f->initstat = makeinit(f, anchor);
f->anchor = anchor;
f->restr = (uschar *) tostring(s);
if (firstbasestr != basestr) {
if (basestr)
xfree(basestr);
}
return f;
}
int makeinit(fa *f, bool anchor)
{
int i, k;
f->curstat = 2;
f->out[2] = 0;
k = *(f->re[0].lfollow);
xfree(f->posns[2]);
f->posns[2] = intalloc(k + 1, __func__);
for (i = 0; i <= k; i++) {
(f->posns[2])[i] = (f->re[0].lfollow)[i];
}
if ((f->posns[2])[1] == f->accept)
f->out[2] = 1;
for (i = 0; i < NCHARS; i++)
set_gototab(f, 2, 0, 0); /* f->gototab[2][i] = 0; */
f->curstat = cgoto(f, 2, HAT);
if (anchor) {
*f->posns[2] = k-1; /* leave out position 0 */
for (i = 0; i < k; i++) {
(f->posns[0])[i] = (f->posns[2])[i];
}
f->out[0] = f->out[2];
if (f->curstat != 2)
--(*f->posns[f->curstat]);
}
return f->curstat;
}
void penter(Node *p) /* set up parent pointers and leaf indices */
{
switch (type(p)) {
ELEAF
LEAF
info(p) = poscnt;
poscnt++;
break;
UNARY
penter(left(p));
parent(left(p)) = p;
break;
case CAT:
case OR:
penter(left(p));
penter(right(p));
parent(left(p)) = p;
parent(right(p)) = p;
break;
case ZERO:
break;
default: /* can't happen */
FATAL("can't happen: unknown type %d in penter", type(p));
break;
}
}
void freetr(Node *p) /* free parse tree */
{
switch (type(p)) {
ELEAF
LEAF
xfree(p);
break;
UNARY
case ZERO:
freetr(left(p));
xfree(p);
break;
case CAT:
case OR:
freetr(left(p));
freetr(right(p));
xfree(p);
break;
default: /* can't happen */
FATAL("can't happen: unknown type %d in freetr", type(p));
break;
}
}
/* in the parsing of regular expressions, metacharacters like . have */
/* to be seen literally; \056 is not a metacharacter. */
int hexstr(const uschar **pp, int max) /* find and eval hex string at pp, return new p */
{ /* only pick up one 8-bit byte (2 chars) */
const uschar *p;
int n = 0;
int i;
for (i = 0, p = *pp; i < max && isxdigit(*p); i++, p++) {
if (isdigit(*p))
n = 16 * n + *p - '0';
else if (*p >= 'a' && *p <= 'f')
n = 16 * n + *p - 'a' + 10;
else if (*p >= 'A' && *p <= 'F')
n = 16 * n + *p - 'A' + 10;
}
*pp = p;
return n;
}
#define isoctdigit(c) ((c) >= '0' && (c) <= '7') /* multiple use of arg */
int quoted(const uschar **pp) /* pick up next thing after a \\ */
/* and increment *pp */
{
const uschar *p = *pp;
int c;
/* BUG: should advance by utf-8 char even if makes no sense */
if ((c = *p++) == 't') {
c = '\t';
} else if (c == 'n') {
c = '\n';
} else if (c == 'f') {
c = '\f';
} else if (c == 'r') {
c = '\r';
} else if (c == 'b') {
c = '\b';
} else if (c == 'v') {
c = '\v';
} else if (c == 'a') {
c = '\a';
} else if (c == '\\') {
c = '\\';
} else if (c == 'x') { /* 2 hex digits follow */
c = hexstr(&p, 2); /* this adds a null if number is invalid */
} else if (c == 'u') { /* unicode char number up to 8 hex digits */
c = hexstr(&p, 8);
} else if (isoctdigit(c)) { /* \d \dd \ddd */
int n = c - '0';
if (isoctdigit(*p)) {
n = 8 * n + *p++ - '0';
if (isoctdigit(*p))
n = 8 * n + *p++ - '0';
}
c = n;
} /* else */
/* c = c; */
*pp = p;
return c;
}
int *cclenter(const char *argp) /* add a character class */
{
int i, c, c2;
int n;
const uschar *p = (const uschar *) argp;
int *bp, *retp;
static int *buf = NULL;
static int bufsz = 100;
if (buf == NULL && (buf = (int *) calloc(bufsz, sizeof(int))) == NULL)
FATAL("out of space for character class [%.10s...] 1", p);
bp = buf;
for (i = 0; *p != 0; ) {
n = u8_rune(&c, p);
p += n;
if (c == '\\') {
c = quoted(&p);
} else if (c == '-' && i > 0 && bp[-1] != 0) {
if (*p != 0) {
c = bp[-1];
/* c2 = *p++; */
n = u8_rune(&c2, p);
p += n;
if (c2 == '\\')
c2 = quoted(&p); /* BUG: sets p, has to be u8 size */
if (c > c2) { /* empty; ignore */
bp--;
i--;
continue;
}
while (c < c2) {
if (i >= bufsz) {
bufsz *= 2;
buf = (int *) realloc(buf, bufsz * sizeof(int));
if (buf == NULL)
FATAL("out of space for character class [%.10s...] 2", p);
bp = buf + i;
}
*bp++ = ++c;
i++;
}
continue;
}
}
if (i >= bufsz) {
bufsz *= 2;
buf = (int *) realloc(buf, bufsz * sizeof(int));
if (buf == NULL)
FATAL("out of space for character class [%.10s...] 2", p);
bp = buf + i;
}
*bp++ = c;
i++;
}
*bp = 0;
/* DPRINTF("cclenter: in = |%s|, out = |%s|\n", op, buf); BUG: can't print array of int */
/* xfree(op); BUG: what are we freeing here? */
retp = (int *) calloc(bp-buf+1, sizeof(int));
for (i = 0; i < bp-buf+1; i++)
retp[i] = buf[i];
return retp;
}
void overflo(const char *s)
{
FATAL("regular expression too big: out of space in %.30s...", s);
}
void cfoll(fa *f, Node *v) /* enter follow set of each leaf of vertex v into lfollow[leaf] */
{
int i;
int *p;
switch (type(v)) {
ELEAF
LEAF
f->re[info(v)].ltype = type(v);
f->re[info(v)].lval.np = right(v);
while (f->accept >= maxsetvec) { /* guessing here! */
resizesetvec(__func__);
}
for (i = 0; i <= f->accept; i++)
setvec[i] = 0;
setcnt = 0;
follow(v); /* computes setvec and setcnt */
p = intalloc(setcnt + 1, __func__);
f->re[info(v)].lfollow = p;
*p = setcnt;
for (i = f->accept; i >= 0; i--)
if (setvec[i] == 1)
*++p = i;
break;
UNARY
cfoll(f,left(v));
break;
case CAT:
case OR:
cfoll(f,left(v));
cfoll(f,right(v));
break;
case ZERO:
break;
default: /* can't happen */
FATAL("can't happen: unknown type %d in cfoll", type(v));
}
}
int first(Node *p) /* collects initially active leaves of p into setvec */
/* returns 0 if p matches empty string */
{
int b, lp;
switch (type(p)) {
ELEAF
LEAF
lp = info(p); /* look for high-water mark of subscripts */
while (setcnt >= maxsetvec || lp >= maxsetvec) { /* guessing here! */
resizesetvec(__func__);
}
if (type(p) == EMPTYRE) {
setvec[lp] = 0;
return(0);
}
if (setvec[lp] != 1) {
setvec[lp] = 1;
setcnt++;
}
if (type(p) == CCL && (*(char *) right(p)) == '\0')
return(0); /* empty CCL */
return(1);
case PLUS:
if (first(left(p)) == 0)
return(0);
return(1);
case STAR:
case QUEST:
first(left(p));
return(0);
case CAT:
if (first(left(p)) == 0 && first(right(p)) == 0) return(0);
return(1);
case OR:
b = first(right(p));
if (first(left(p)) == 0 || b == 0) return(0);
return(1);
case ZERO:
return 0;
}
FATAL("can't happen: unknown type %d in first", type(p)); /* can't happen */
return(-1);
}
void follow(Node *v) /* collects leaves that can follow v into setvec */
{
Node *p;
if (type(v) == FINAL)
return;
p = parent(v);
switch (type(p)) {
case STAR:
case PLUS:
first(v);
follow(p);
return;
case OR:
case QUEST:
follow(p);
return;
case CAT:
if (v == left(p)) { /* v is left child of p */
if (first(right(p)) == 0) {
follow(p);
return;
}
} else /* v is right child */
follow(p);
return;
}
}
int member(int c, int *sarg) /* is c in s? */
{
int *s = (int *) sarg;
while (*s)
if (c == *s++)
return(1);
return(0);
}
static int get_gototab(fa *f, int state, int ch) /* hide gototab inplementation */
{
int i;
for (i = 0; i < f->gototab_len; i++) {
if (f->gototab[state][i].ch == 0)
break;
if (f->gototab[state][i].ch == ch)
return f->gototab[state][i].state;
}
return 0;
}
static int set_gototab(fa *f, int state, int ch, int val) /* hide gototab inplementation */
{
int i;
for (i = 0; i < f->gototab_len; i++) {
if (f->gototab[state][i].ch == 0 || f->gototab[state][i].ch == ch) {
f->gototab[state][i].ch = ch;
f->gototab[state][i].state = val;
return val;
}
}
overflo(__func__);
return val; /* not used anywhere at the moment */
}
int match(fa *f, const char *p0) /* shortest match ? */
{
int s, ns;
int n;
int rune;
const uschar *p = (const uschar *) p0;
/* return pmatch(f, p0); does it matter whether longest or shortest? */
s = f->initstat;
assert (s < f->state_count);
if (f->out[s])
return(1);
do {
/* assert(*p < NCHARS); */
n = u8_rune(&rune, p);
if ((ns = get_gototab(f, s, rune)) != 0)
s = ns;
else
s = cgoto(f, s, rune);
if (f->out[s])
return(1);
if (*p == 0)
break;
p += n;
} while (1); /* was *p++ != 0 */
return(0);
}
int pmatch(fa *f, const char *p0) /* longest match, for sub */
{
int s, ns;
int n;
int rune;
const uschar *p = (const uschar *) p0;
const uschar *q;
s = f->initstat;
assert(s < f->state_count);
patbeg = (const char *)p;
patlen = -1;
do {
q = p;
do {
if (f->out[s]) /* final state */
patlen = q-p;
/* assert(*q < NCHARS); */
n = u8_rune(&rune, q);
if ((ns = get_gototab(f, s, rune)) != 0)
s = ns;
else
s = cgoto(f, s, rune);
assert(s < f->state_count);
if (s == 1) { /* no transition */
if (patlen >= 0) {
patbeg = (const char *) p;
return(1);
}
else
goto nextin; /* no match */
}
if (*q == 0)
break;
q += n;
} while (1);
q++; /* was *q++ */
if (f->out[s])
patlen = q-p-1; /* don't count $ */
if (patlen >= 0) {
patbeg = (const char *) p;
return(1);
}
nextin:
s = 2;
if (*p == 0)
break;
n = u8_rune(&rune, p);
p += n;
} while (1); /* was *p++ */
return (0);
}
int nematch(fa *f, const char *p0) /* non-empty match, for sub */
{
int s, ns;
int n;
int rune;
const uschar *p = (const uschar *) p0;
const uschar *q;
s = f->initstat;
assert(s < f->state_count);
patbeg = (const char *)p;
patlen = -1;
while (*p) {
q = p;
do {
if (f->out[s]) /* final state */
patlen = q-p;
/* assert(*q < NCHARS); */
n = u8_rune(&rune, q);
if ((ns = get_gototab(f, s, rune)) != 0)
s = ns;
else
s = cgoto(f, s, rune);
if (s == 1) { /* no transition */
if (patlen > 0) {
patbeg = (const char *) p;
return(1);
} else
goto nnextin; /* no nonempty match */
}
if (*q == 0)
break;
q += n;
} while (1);
q++;
if (f->out[s])
patlen = q-p-1; /* don't count $ */
if (patlen > 0 ) {
patbeg = (const char *) p;
return(1);
}
nnextin:
s = 2;
p++;
}
return (0);
}
#define MAX_UTF_BYTES 4 // UTF-8 is up to 4 bytes long
// Read one rune at a time from the given FILE*. Return both
// the bytes and the actual rune.
struct runedata {
int rune;
size_t len;
char bytes[6];
};
struct runedata getrune(FILE *fp)
{
struct runedata result;
int c, next;
memset(&result, 0, sizeof(result));
c = getc(fp);
if (c == EOF)
return result; // result.rune == 0 --> EOF
else if (c < 128) {
result.bytes[0] = c;
result.len = 1;
result.rune = c;
return result;
}
// need to get bytes and fill things in
result.bytes[0] = c;
result.len = 1;
next = 1;
for (int i = 1; i < MAX_UTF_BYTES; i++) {
c = getc(fp);
if (c == EOF)
break;
result.bytes[next++] = c;
result.len++;
}
// put back any extra input bytes
int actual_len = u8_nextlen(result.bytes);
while (result.len > actual_len) {
ungetc(result.bytes[--result.len], fp);
}
result.bytes[result.len] = '\0';
(void) u8_rune(& result.rune, (uschar *) result.bytes);
return result;
}
/*
* NAME
* fnematch
*
* DESCRIPTION
* A stream-fed version of nematch which transfers characters to a
* null-terminated buffer. All characters up to and including the last
* character of the matching text or EOF are placed in the buffer. If
* a match is found, patbeg and patlen are set appropriately.
*
* RETURN VALUES
* false No match found.
* true Match found.
*/
bool fnematch(fa *pfa, FILE *f, char **pbuf, int *pbufsize, int quantum)
{
char *buf = *pbuf;
int bufsize = *pbufsize;
int i, j, k, ns, s;
struct runedata r;
s = pfa->initstat;
patlen = 0;
/*
* All indices relative to buf.
* i <= j <= k <= bufsize
*
* i: origin of active substring (first byte of first character)
* j: current character (last byte of current character)
* k: destination of next getc()
*/
i = -1, k = 0;
do {
j = i++;
do {
r = getrune(f);
if ((++j + r.len) >= k) {
if (k >= bufsize)
if (!adjbuf((char **) &buf, &bufsize, bufsize+1, quantum, 0, "fnematch"))
FATAL("stream '%.30s...' too long", buf);
}
memcpy(buf + k, r.bytes, r.len);
j += r.len - 1; // incremented next time around the loop
k += r.len;
if ((ns = get_gototab(pfa, s, r.rune)) != 0)
s = ns;
else
s = cgoto(pfa, s, r.rune);
if (pfa->out[s]) { /* final state */
patlen = j - i + 1;
if (r.rune == 0) /* don't count $ */
patlen--;
}
} while (buf[j] && s != 1);
s = 2;
if (r.len > 1)
i += r.len - 1; // i incremented around the loop
} while (buf[i] && !patlen);
/* adjbuf() may have relocated a resized buffer. Inform the world. */
*pbuf = buf;
*pbufsize = bufsize;
if (patlen) {
patbeg = (char *) buf + i;
/*
* Under no circumstances is the last character fed to
* the automaton part of the match. It is EOF's nullbyte,
* or it sent the automaton into a state with no further
* transitions available (s==1), or both. Room for a
* terminating nullbyte is guaranteed.
*
* ungetc any chars after the end of matching text
* (except for EOF's nullbyte, if present) and null
* terminate the buffer.
*/
do
for (int ii = r.len; ii > 0; ii--)
if (buf[--k] && ungetc(buf[k], f) == EOF)
FATAL("unable to ungetc '%c'", buf[k]);
while (k > i + patlen);
buf[k] = '\0';
return true;
}
else
return false;
}
Node *reparse(const char *p) /* parses regular expression pointed to by p */
{ /* uses relex() to scan regular expression */
Node *np;
DPRINTF("reparse <%s>\n", p);
lastre = prestr = (const uschar *) p; /* prestr points to string to be parsed */
rtok = relex();
/* GNU compatibility: an empty regexp matches anything */
if (rtok == '\0') {
/* FATAL("empty regular expression"); previous */
return(op2(EMPTYRE, NIL, NIL));
}
np = regexp();
if (rtok != '\0')
FATAL("syntax error in regular expression %s at %s", lastre, prestr);
return(np);
}
Node *regexp(void) /* top-level parse of reg expr */
{
return (alt(concat(primary())));
}
Node *primary(void)
{
Node *np;
int savelastatom;
switch (rtok) {
case CHAR:
lastatom = starttok;
np = op2(CHAR, NIL, itonp(rlxval));
rtok = relex();
return (unary(np));
case ALL:
rtok = relex();
return (unary(op2(ALL, NIL, NIL)));
case EMPTYRE:
rtok = relex();
return (unary(op2(EMPTYRE, NIL, NIL)));
case DOT:
lastatom = starttok;
rtok = relex();
return (unary(op2(DOT, NIL, NIL)));
case CCL:
np = op2(CCL, NIL, (Node*) cclenter((const char *) rlxstr));
lastatom = starttok;
rtok = relex();
return (unary(np));
case NCCL:
np = op2(NCCL, NIL, (Node *) cclenter((const char *) rlxstr));
lastatom = starttok;
rtok = relex();
return (unary(np));
case '^':
rtok = relex();
return (unary(op2(CHAR, NIL, itonp(HAT))));
case '$':
rtok = relex();
return (unary(op2(CHAR, NIL, NIL)));
case '(':
lastatom = starttok;
savelastatom = starttok - basestr; /* Retain over recursion */
rtok = relex();
if (rtok == ')') { /* special pleading for () */
rtok = relex();
return unary(op2(CCL, NIL, (Node *) tostring("")));
}
np = regexp();
if (rtok == ')') {
lastatom = basestr + savelastatom; /* Restore */
rtok = relex();
return (unary(np));
}
else
FATAL("syntax error in regular expression %s at %s", lastre, prestr);
default:
FATAL("illegal primary in regular expression %s at %s", lastre, prestr);
}
return 0; /*NOTREACHED*/
}
Node *concat(Node *np)
{
switch (rtok) {
case CHAR: case DOT: case ALL: case CCL: case NCCL: case '$': case '(':
return (concat(op2(CAT, np, primary())));
case EMPTYRE:
rtok = relex();
return (concat(op2(CAT, op2(CCL, NIL, (Node *) tostring("")),
primary())));
}
return (np);
}