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luapatt.c
329 lines (292 loc) · 9.51 KB
/
luapatt.c
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/* Unmodified pattern matcher from Lua 5.2.3: lstrlib.c:187:510
*
* See top-level COPYING file for Lua's license.
*/
/*
** {======================================================
** PATTERN MATCHING
** =======================================================
*/
#define CAP_UNFINISHED (-1)
#define CAP_POSITION (-2)
typedef struct MatchState {
int matchdepth; /* control for recursive depth (to avoid C stack overflow) */
const char *src_init; /* init of source string */
const char *src_end; /* end ('\0') of source string */
const char *p_end; /* end ('\0') of pattern */
lua_State *L;
int level; /* total number of captures (finished or unfinished) */
struct {
const char *init;
ptrdiff_t len;
} capture[LUA_MAXCAPTURES];
} MatchState;
/* recursive function */
static const char *match (MatchState *ms, const char *s, const char *p);
/* maximum recursion depth for 'match' */
#if !defined(MAXCCALLS)
#define MAXCCALLS 200
#endif
#define L_ESC '%'
#define SPECIALS "^$*+?.([%-"
static int check_capture (MatchState *ms, int l) {
l -= '1';
if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
return luaL_error(ms->L, "invalid capture index %%%d", l + 1);
return l;
}
static int capture_to_close (MatchState *ms) {
int level = ms->level;
for (level--; level>=0; level--)
if (ms->capture[level].len == CAP_UNFINISHED) return level;
return luaL_error(ms->L, "invalid pattern capture");
}
static const char *classend (MatchState *ms, const char *p) {
switch (*p++) {
case L_ESC: {
if (p == ms->p_end)
luaL_error(ms->L, "malformed pattern (ends with " LUA_QL("%%") ")");
return p+1;
}
case '[': {
if (*p == '^') p++;
do { /* look for a `]' */
if (p == ms->p_end)
luaL_error(ms->L, "malformed pattern (missing " LUA_QL("]") ")");
if (*(p++) == L_ESC && p < ms->p_end)
p++; /* skip escapes (e.g. `%]') */
} while (*p != ']');
return p+1;
}
default: {
return p;
}
}
}
static int match_class (int c, int cl) {
int res;
switch (tolower(cl)) {
case 'a' : res = isalpha(c); break;
case 'c' : res = iscntrl(c); break;
case 'd' : res = isdigit(c); break;
case 'g' : res = isgraph(c); break;
case 'l' : res = islower(c); break;
case 'p' : res = ispunct(c); break;
case 's' : res = isspace(c); break;
case 'u' : res = isupper(c); break;
case 'w' : res = isalnum(c); break;
case 'x' : res = isxdigit(c); break;
case 'z' : res = (c == 0); break; /* deprecated option */
default: return (cl == c);
}
return (islower(cl) ? res : !res);
}
static int matchbracketclass (int c, const char *p, const char *ec) {
int sig = 1;
if (*(p+1) == '^') {
sig = 0;
p++; /* skip the `^' */
}
while (++p < ec) {
if (*p == L_ESC) {
p++;
if (match_class(c, uchar(*p)))
return sig;
}
else if ((*(p+1) == '-') && (p+2 < ec)) {
p+=2;
if (uchar(*(p-2)) <= c && c <= uchar(*p))
return sig;
}
else if (uchar(*p) == c) return sig;
}
return !sig;
}
static int singlematch (MatchState *ms, const char *s, const char *p,
const char *ep) {
if (s >= ms->src_end)
return 0;
else {
int c = uchar(*s);
switch (*p) {
case '.': return 1; /* matches any char */
case L_ESC: return match_class(c, uchar(*(p+1)));
case '[': return matchbracketclass(c, p, ep-1);
default: return (uchar(*p) == c);
}
}
}
static const char *matchbalance (MatchState *ms, const char *s,
const char *p) {
if (p >= ms->p_end - 1)
luaL_error(ms->L, "malformed pattern "
"(missing arguments to " LUA_QL("%%b") ")");
if (*s != *p) return NULL;
else {
int b = *p;
int e = *(p+1);
int cont = 1;
while (++s < ms->src_end) {
if (*s == e) {
if (--cont == 0) return s+1;
}
else if (*s == b) cont++;
}
}
return NULL; /* string ends out of balance */
}
static const char *max_expand (MatchState *ms, const char *s,
const char *p, const char *ep) {
ptrdiff_t i = 0; /* counts maximum expand for item */
while (singlematch(ms, s + i, p, ep))
i++;
/* keeps trying to match with the maximum repetitions */
while (i>=0) {
const char *res = match(ms, (s+i), ep+1);
if (res) return res;
i--; /* else didn't match; reduce 1 repetition to try again */
}
return NULL;
}
static const char *min_expand (MatchState *ms, const char *s,
const char *p, const char *ep) {
for (;;) {
const char *res = match(ms, s, ep+1);
if (res != NULL)
return res;
else if (singlematch(ms, s, p, ep))
s++; /* try with one more repetition */
else return NULL;
}
}
static const char *start_capture (MatchState *ms, const char *s,
const char *p, int what) {
const char *res;
int level = ms->level;
if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
ms->capture[level].init = s;
ms->capture[level].len = what;
ms->level = level+1;
if ((res=match(ms, s, p)) == NULL) /* match failed? */
ms->level--; /* undo capture */
return res;
}
static const char *end_capture (MatchState *ms, const char *s,
const char *p) {
int l = capture_to_close(ms);
const char *res;
ms->capture[l].len = s - ms->capture[l].init; /* close capture */
if ((res = match(ms, s, p)) == NULL) /* match failed? */
ms->capture[l].len = CAP_UNFINISHED; /* undo capture */
return res;
}
static const char *match_capture (MatchState *ms, const char *s, int l) {
size_t len;
l = check_capture(ms, l);
len = ms->capture[l].len;
if ((size_t)(ms->src_end-s) >= len &&
memcmp(ms->capture[l].init, s, len) == 0)
return s+len;
else return NULL;
}
static const char *match (MatchState *ms, const char *s, const char *p) {
if (ms->matchdepth-- == 0)
luaL_error(ms->L, "pattern too complex");
init: /* using goto's to optimize tail recursion */
if (p != ms->p_end) { /* end of pattern? */
switch (*p) {
case '(': { /* start capture */
if (*(p + 1) == ')') /* position capture? */
s = start_capture(ms, s, p + 2, CAP_POSITION);
else
s = start_capture(ms, s, p + 1, CAP_UNFINISHED);
break;
}
case ')': { /* end capture */
s = end_capture(ms, s, p + 1);
break;
}
case '$': {
if ((p + 1) != ms->p_end) /* is the `$' the last char in pattern? */
goto dflt; /* no; go to default */
s = (s == ms->src_end) ? s : NULL; /* check end of string */
break;
}
case L_ESC: { /* escaped sequences not in the format class[*+?-]? */
switch (*(p + 1)) {
case 'b': { /* balanced string? */
s = matchbalance(ms, s, p + 2);
if (s != NULL) {
p += 4; goto init; /* return match(ms, s, p + 4); */
} /* else fail (s == NULL) */
break;
}
case 'f': { /* frontier? */
const char *ep; char previous;
p += 2;
if (*p != '[')
luaL_error(ms->L, "missing " LUA_QL("[") " after "
LUA_QL("%%f") " in pattern");
ep = classend(ms, p); /* points to what is next */
previous = (s == ms->src_init) ? '\0' : *(s - 1);
if (!matchbracketclass(uchar(previous), p, ep - 1) &&
matchbracketclass(uchar(*s), p, ep - 1)) {
p = ep; goto init; /* return match(ms, s, ep); */
}
s = NULL; /* match failed */
break;
}
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
case '8': case '9': { /* capture results (%0-%9)? */
s = match_capture(ms, s, uchar(*(p + 1)));
if (s != NULL) {
p += 2; goto init; /* return match(ms, s, p + 2) */
}
break;
}
default: goto dflt;
}
break;
}
default: dflt: { /* pattern class plus optional suffix */
const char *ep = classend(ms, p); /* points to optional suffix */
/* does not match at least once? */
if (!singlematch(ms, s, p, ep)) {
if (*ep == '*' || *ep == '?' || *ep == '-') { /* accept empty? */
p = ep + 1; goto init; /* return match(ms, s, ep + 1); */
}
else /* '+' or no suffix */
s = NULL; /* fail */
}
else { /* matched once */
switch (*ep) { /* handle optional suffix */
case '?': { /* optional */
const char *res;
if ((res = match(ms, s + 1, ep + 1)) != NULL)
s = res;
else {
p = ep + 1; goto init; /* else return match(ms, s, ep + 1); */
}
break;
}
case '+': /* 1 or more repetitions */
s++; /* 1 match already done */
/* go through */
case '*': /* 0 or more repetitions */
s = max_expand(ms, s, p, ep);
break;
case '-': /* 0 or more repetitions (minimum) */
s = min_expand(ms, s, p, ep);
break;
default: /* no suffix */
s++; p = ep; goto init; /* return match(ms, s + 1, ep); */
}
}
break;
}
}
}
ms->matchdepth++;
return s;
}