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/*
* Copyright (c) 2004-2013 Sergey Lyubka <valenok@gmail.com>
* Copyright (c) 2013 Cesanta Software Limited
* All rights reserved
*
* This library is dual-licensed: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation. For the terms of this
* license, see <http://www.gnu.org/licenses/>.
*
* You are free to use this library under the terms of the GNU General
* Public License, but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* Alternatively, you can license this library under a commercial
* license, as set out in <http://cesanta.com/products.html>.
*/
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include "slre.h"
static const char *static_error_no_match = "No match";
static const char *static_error_unexpected_quantifier = "Unexpected quantifier";
static const char *static_error_unbalanced_brackets = "Unbalanced brackets";
static const char *static_error_internal = "Internal error";
static const char *static_error_invalid_metacharacter = "Invalid metacharacter";
#define MAX_BRANCHES 100
#define MAX_BRACKETS 100
#define ARRAY_SIZE(ar) (int) (sizeof(ar) / sizeof((ar)[0]))
#define FAIL_IF(cond,msg) do { if (cond) \
{info->error_msg = msg; return 0; }} while (0)
#ifdef SLRE_DEBUG
#define DBG(x) printf x
#else
#define DBG(x)
#endif
struct regex_info {
/*
* Describes all bracket pairs in the regular expression.
* First entry is always present, and grabs the whole regex.
*/
struct bracket_pair {
const char *ptr; /* Points to the first char after '(' in regex */
int len; /* Length of the text between '(' and ')' */
int branches; /* Index in the branches array for this pair */
int num_branches; /* Number of '|' in this bracket pair */
} brackets[MAX_BRACKETS];
int num_brackets;
/*
* Describes alternations ('|' operators) in the regular expression.
* Each branch falls into a specific branch pair.
*/
struct branch {
int bracket_index; /* index into 'brackets' array defined above */
const char *schlong; /* points to the '|' character in the regex */
} branches[MAX_BRANCHES];
int num_branches;
/* Error message to be returned to the user */
const char *error_msg;
/* E.g. IGNORE_CASE. See enum below */
int flags;
};
enum { IGNORE_CASE = 1 };
static int get_op_len(const char *re) {
return re[0] == '\\' ? 2 : 1;
}
static int is_quantifier(const char *re) {
return re[0] == '*' || re[0] == '+' || re[0] == '?';
}
static int doh(const char *s, int s_len,
struct slre_cap *caps, struct regex_info *info, int bi);
static int bar(const char *re, int re_len, const char *s, int s_len,
struct slre_cap *caps, struct regex_info *info, int bi) {
/* i is offset in re, j is offset in s, bi is brackets index */
int i, j, n, step;
(void) caps;
DBG(("%s [%.*s] [%.*s]\n", __func__, re_len, re, s_len, s));
for (i = j = 0; i < re_len && j < s_len; i += step) {
step = get_op_len(re + i);
DBG(("%s [%.*s] [%.*s] re_len=%d step=%d i=%d j=%d\n",
__func__, re_len - i, re + i,
s_len - j, s + j, re_len, step, i, j));
FAIL_IF(is_quantifier(&re[i]), static_error_unexpected_quantifier);
FAIL_IF(step <= 0, static_error_internal);
/* Handle quantifiers. Look ahead. */
if (i + step < re_len && is_quantifier(re + i + step)) {
if (re[i + step] == '?') {
j += bar(re + i, step, s + j, s_len - j, caps, info, bi);
i++;
continue;
} else if (re[i + step] == '+' || re[i + step] == '*') {
int j2 = j, nj = 0, n1, n2, ni, next_step, non_greedy = 0;
/* Points to the regexp code after the quantifier */
next_step = get_op_len(re + i + step);
if (i + step + 1 < re_len && re[i + step + 1] == '?') {
non_greedy = 1;
next_step++;
}
ni = i + step + next_step;
while ((n1 = bar(re + i, step, s + j2, s_len - j2,
caps, info, bi)) > 0) {
if (ni >= re_len) {
/* After quantifier, there is nothing */
nj = j2 + n1;
} else if ((n2 = bar(re + ni, re_len - ni, s + j2 + n1,
s_len - (j2 + n1), caps, info, bi)) > 0) {
nj = j2 + n1 + n2;
}
if (nj > 0 && non_greedy) break;
j2 += n1;
}
FAIL_IF(re[i + step] == '+' && nj == 0, static_error_no_match);
return nj;
}
}
switch (re[i]) {
case '\\':
/* Metacharacters */
switch (re[i + 1]) {
case 'S':
FAIL_IF(isspace(((unsigned char *) s)[j]), static_error_no_match);
j++;
break;
case 's':
FAIL_IF(!isspace(((unsigned char *) s)[j]), static_error_no_match);
j++;
break;
case 'd':
FAIL_IF(!isdigit(((unsigned char *) s)[j]), static_error_no_match);
j++;
break;
case '+': case '?': case '*': case '\\': case '(': case ')':
case '^': case '$': case '.': case '[': case ']':
FAIL_IF(re[i + 1] != s[j], static_error_no_match);
j++;
break;
default:
FAIL_IF(1, static_error_invalid_metacharacter);
break;
}
break;
case '(':
bi++;
FAIL_IF(bi >= info->num_brackets, static_error_internal);
DBG(("CAPTURING [%.*s] [%.*s]\n", info->brackets[bi].len + 2,
re + i, s_len - j, s + j));
n = doh(s + j, s_len - j, caps, info, bi);
DBG(("CAPTURED [%.*s] [%.*s]:%d\n", info->brackets[bi].len + 2,
re + i, s_len - j, s + j, n));
FAIL_IF(n <= 0, static_error_no_match);
if (caps != NULL) {
caps[bi - 1].ptr = s + j;
caps[bi - 1].len = n;
}
j += n;
i += info->brackets[bi].len + 1;
break;
case '^':
FAIL_IF(j != 0, static_error_no_match);
break;
case '|':
FAIL_IF(1, static_error_internal);
break;
case '$':
/* $ anchor handling is at the end of this function */
FAIL_IF(1, static_error_no_match);
break;
case '.':
j++;
break;
default:
FAIL_IF(re[i] != s[j], static_error_no_match);
j++;
break;
}
}
/*
* Process $ anchor here. If we've reached the end of the string,
* but did not exhaust regexp yet, this is no match.
*/
FAIL_IF(i < re_len && !(re[i] == '$' && i + 1 == re_len),
static_error_no_match);
return j;
}
/* Process branch points */
static int doh(const char *s, int s_len,
struct slre_cap *caps, struct regex_info *info, int bi) {
const struct bracket_pair *b = &info->brackets[bi];
int i = 0, len, result;
const char *p;
do {
p = i == 0 ? b->ptr : info->branches[b->branches + i - 1].schlong + 1;
len = b->num_branches == 0 ? b->len :
i == b->num_branches ? b->ptr + b->len - p :
info->branches[b->branches + i].schlong - p;
DBG(("%s %d %d [%.*s]\n", __func__, bi, i, len, p));
result = bar(p, len, s, s_len, caps, info, bi);
} while (i++ < b->num_branches); /* At least 1 iteration */
return result;
}
static void setup_branch_points(struct regex_info *info) {
int i, j;
struct branch tmp;
/* First, sort branches. Must be stable, no qsort. Use bubble algo. */
for (i = 0; i < info->num_branches; i++) {
for (j = i + 1; j < info->num_branches; j++) {
if (info->branches[i].bracket_index > info->branches[j].bracket_index) {
tmp = info->branches[i];
info->branches[i] = info->branches[j];
info->branches[j] = tmp;
}
}
}
/*
* For each bracket, set their branch points. This way, for every bracket
* (i.e. every chunk of regex) we know all branch points before matching.
*/
for (i = j = 0; i < info->num_brackets; i++) {
info->brackets[i].num_branches = 0;
info->brackets[i].branches = j;
while (j < info->num_branches && info->branches[j].bracket_index == i) {
info->brackets[i].num_branches++;
j++;
}
}
}
static int foo(const char *re, int re_len, const char *s, int s_len,
struct slre_cap *caps, struct regex_info *info) {
int result, i, step, depth = 0;
const char *stack[ARRAY_SIZE(info->brackets)];
stack[0] = re;
/* First bracket captures everything */
info->brackets[0].ptr = re;
info->brackets[0].len = re_len;
info->num_brackets = 1;
/* Make a single pass over regex string, memorize brackets and branches */
for (i = 0; i < re_len; i += step) {
step = get_op_len(&re[i]);
if (re[i] == '|') {
FAIL_IF(info->num_branches >= ARRAY_SIZE(info->branches),
"Too many |. Increase MAX_BRANCHES");
info->branches[info->num_branches].bracket_index =
info->brackets[info->num_brackets - 1].len == -1 ?
info->num_brackets - 1 : depth;
info->branches[info->num_branches].schlong = &re[i];
info->num_branches++;
} else if (re[i] == '(') {
FAIL_IF(info->num_brackets >= ARRAY_SIZE(info->brackets),
"Too many (. Increase MAX_BRACKETS");
depth++; /* Order is important here. Depth increments first. */
stack[depth] = &re[i];
info->brackets[info->num_brackets].ptr = re + i + 1;
info->brackets[info->num_brackets].len = -1;
info->num_brackets++;
} else if (re[i] == ')') {
int ind = info->brackets[info->num_brackets - 1].len == -1 ?
info->num_brackets - 1 : depth;
info->brackets[ind].len = &re[i] - info->brackets[ind].ptr;
DBG(("SETTING BRACKET %d [%.*s]\n",
ind, info->brackets[ind].len, info->brackets[ind].ptr));
depth--;
FAIL_IF(depth < 0, static_error_unbalanced_brackets);
FAIL_IF(i > 0 && re[i - 1] == '(', static_error_no_match);
}
}
FAIL_IF(depth != 0, static_error_unbalanced_brackets);
setup_branch_points(info);
/* Scan the string from left to right, applying the regex. Stop on match. */
result = 0;
for (i = 0; i < s_len; i++) {
result = doh(s + i, s_len - i, caps, info, 0);
DBG((" (iter) -> %d [%.*s] [%.*s] [%s]\n", result, re_len, re,
s_len - i, s + i, info->error_msg));
if (result > 0 || re[0] == '^') {
result += i;
break;
}
}
return result;
}
int slre_match(const char *regexp, const char *s, int s_len,
struct slre_cap *caps, const char **error_msg) {
struct regex_info info;
int result;
/* Initialize info structure */
info.flags = info.num_brackets = info.num_branches = 0;
info.error_msg = static_error_no_match;
DBG(("========================> [%s] [%.*s]\n", regexp, s_len, s));
result = foo(regexp, strlen(regexp), s, s_len, caps, &info);
if (error_msg != NULL) {
*error_msg = info.error_msg;
}
return result;
}
/*****************************************************************************/
/********************************** UNIT TEST ********************************/
/*****************************************************************************/
#ifdef SLRE_UNIT_TEST
static int static_total_tests = 0;
static int static_failed_tests = 0;
#define FAIL(str, line) do { \
printf("Fail on line %d: [%s]\n", line, str); \
static_failed_tests++; \
} while (0)
#define ASSERT(expr) do { \
static_total_tests++; \
if (!(expr)) FAIL(#expr, __LINE__); \
} while (0)
int main(void) {
const char *msg = "";
struct slre_cap caps[10];
#if 0
#endif
ASSERT(slre_match("fo", "foo", 3, NULL, &msg) == 2);
ASSERT(slre_match(".+", "foo", 3, NULL, &msg) == 3);
ASSERT(slre_match(".+k", "fooklmn", 7, NULL, &msg) == 4);
ASSERT(slre_match(".+k.", "fooklmn", 7, NULL, &msg) == 5);
ASSERT(slre_match("p+", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(slre_match("ok", "fooklmn", 7, NULL, &msg) == 4);
ASSERT(slre_match("lmno", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(slre_match("mn.", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(slre_match("o", "fooklmn", 7, NULL, &msg) == 2);
ASSERT(slre_match("^o", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(slre_match("^", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(slre_match("n$", "fooklmn", 7, NULL, &msg) == 7);
ASSERT(slre_match("n$k", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(slre_match("l$", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(slre_match(".$", "fooklmn", 7, NULL, &msg) == 7);
ASSERT(slre_match("a?", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(slre_match("\\_", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(strcmp(msg, static_error_invalid_metacharacter) == 0);
ASSERT(slre_match("+", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(strcmp(msg, static_error_unexpected_quantifier) == 0);
ASSERT(slre_match("()+", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(strcmp(msg, static_error_no_match) == 0);
/* Balancing brackets */
ASSERT(slre_match("(x))", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(strcmp(msg, static_error_unbalanced_brackets) == 0);
ASSERT(slre_match("(", "fooklmn", 7, NULL, &msg) == 0);
ASSERT(strcmp(msg, static_error_unbalanced_brackets) == 0);
ASSERT(slre_match("klz?mn", "fooklmn", 7, NULL, &msg) == 7);
ASSERT(slre_match("fa?b", "fooklmn", 7, NULL, &msg) == 0);
/* Brackets & capturing */
ASSERT(slre_match("^(te)", "tenacity subdues all", 20, caps, &msg) == 2);
ASSERT(slre_match("(bc)", "abcdef", 6, caps, &msg) == 3);
ASSERT(slre_match(".(d.)", "abcdef", 6, caps, &msg) == 5);
ASSERT(slre_match(".(d.)\\)?", "abcdef", 6, caps, &msg) == 5);
ASSERT(caps[0].len == 2);
ASSERT(memcmp(caps[0].ptr, "de", 2) == 0);
ASSERT(slre_match("(.+)", "123", 3, caps, &msg) == 3);
ASSERT(slre_match("(2.+)", "123", 3, caps, &msg) == 3);
ASSERT(caps[0].len == 2);
ASSERT(memcmp(caps[0].ptr, "23", 2) == 0);
ASSERT(slre_match("(.+2)", "123", 3, caps, &msg) == 2);
ASSERT(caps[0].len == 2);
ASSERT(memcmp(caps[0].ptr, "12", 2) == 0);
ASSERT(slre_match("(.*(2.))", "123", 3, caps, &msg) == 3);
ASSERT(slre_match("(.)(.)", "123", 3, caps, &msg) == 2);
ASSERT(slre_match("(\\d+)\\s+(\\S+)", "12 hi", 5, caps, &msg) == 5);
/* Greedy vs non-greedy */
ASSERT(slre_match(".+c", "abcabc", 6, NULL, &msg) == 6);
ASSERT(slre_match(".+?c", "abcabc", 6, NULL, &msg) == 3);
ASSERT(slre_match(".*?c", "abcabc", 6, NULL, &msg) == 3);
ASSERT(slre_match(".*c", "abcabc", 6, NULL, &msg) == 6);
ASSERT(slre_match("bc.d?k?b+", "abcabc", 6, NULL, &msg) == 5);
/* Branching */
ASSERT(slre_match("|", "abc", 3, NULL, &msg) == 0);
ASSERT(slre_match("|.", "abc", 3, NULL, &msg) == 1);
ASSERT(slre_match("x|y|b", "abc", 3, NULL, &msg) == 2);
ASSERT(slre_match("k(xx|yy)|ca", "abcabc", 6, NULL, &msg) == 4);
ASSERT(slre_match("k(xx|yy)|ca|bc", "abcabc", 6, NULL, &msg) == 3);
ASSERT(slre_match("(|.c)", "abc", 3, caps, &msg) == 3);
ASSERT(caps[0].len == 2);
ASSERT(memcmp(caps[0].ptr, "bc", 2) == 0);
/* Example: HTTP request */
{
const char *error_msg, *request = " GET /index.html HTTP/1.0\r\n\r\n";
struct slre_cap caps[4];
if (slre_match("^\\s*(\\S+)\\s+(\\S+)\\s+HTTP/(\\d)\\.(\\d)",
request, strlen(request), caps, &error_msg)) {
printf("Method: [%.*s], URI: [%.*s]\n",
caps[0].len, caps[0].ptr,
caps[1].len, caps[1].ptr);
} else {
printf("Error parsing [%s]: [%s]\n", request, error_msg);
}
}
printf("Unit test %s (total test: %d, failed tests: %d)\n",
static_failed_tests > 0 ? "FAILED" : "PASSED",
static_total_tests, static_failed_tests);
return EXIT_SUCCESS;
}
#endif /* SLRE_UNIT_TEST */