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Add advanced pattern matching facilities.
This commit adds much more advanced pattern matching facilities to CCTools. The pattern matcher is pulled from Lua 5.2 source code. Lua's pattern matching is documented in [1]. Lua is distributed under the MIT license which is GPLv2 compatible. The total lines of code are: $ wc -l dttools/src/pattern.c dttools/src/luapatt.c dttools/src/pattern.h 78 dttools/src/pattern.c 329 dttools/src/luapatt.c 25 dttools/src/pattern.h 432 total Which is a pretty small price for what it gives us. For example, we can now do: const char *subject = "option = 42"; char *number = NULL; ptrdiff_t where = pattern_match(subject, "^option%s*=%s*(%d+)$", &number); if (where >= 0) { n = atoi(number); /* 42 */ free(number); } [1] http://www.lua.org/manual/5.2/manual.html#6.4.1
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Patrick Donnelly
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Aug 1, 2014
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Original file line number | Diff line number | Diff line change |
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/* Unmodified pattern matcher from Lua 5.2.3: lstrlib.c:187:510 | ||
* | ||
* See top-level COPYING file for Lua's license. | ||
*/ | ||
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/* | ||
** {====================================================== | ||
** PATTERN MATCHING | ||
** ======================================================= | ||
*/ | ||
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#define CAP_UNFINISHED (-1) | ||
#define CAP_POSITION (-2) | ||
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typedef struct MatchState { | ||
int matchdepth; /* control for recursive depth (to avoid C stack overflow) */ | ||
const char *src_init; /* init of source string */ | ||
const char *src_end; /* end ('\0') of source string */ | ||
const char *p_end; /* end ('\0') of pattern */ | ||
lua_State *L; | ||
int level; /* total number of captures (finished or unfinished) */ | ||
struct { | ||
const char *init; | ||
ptrdiff_t len; | ||
} capture[LUA_MAXCAPTURES]; | ||
} MatchState; | ||
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/* recursive function */ | ||
static const char *match (MatchState *ms, const char *s, const char *p); | ||
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/* maximum recursion depth for 'match' */ | ||
#if !defined(MAXCCALLS) | ||
#define MAXCCALLS 200 | ||
#endif | ||
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#define L_ESC '%' | ||
#define SPECIALS "^$*+?.([%-" | ||
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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; | ||
} | ||
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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"); | ||
} | ||
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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; | ||
} | ||
} | ||
} | ||
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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); | ||
} | ||
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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; | ||
} | ||
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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); | ||
} | ||
} | ||
} | ||
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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 */ | ||
} | ||
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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; | ||
} | ||
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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; | ||
} | ||
} | ||
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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; | ||
} | ||
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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; | ||
} | ||
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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; | ||
} | ||
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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; | ||
} |
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