/*
*
* Mini regex-module inspired by Rob Pike's regex code described in:
*
* http://www.cs.princeton.edu/courses/archive/spr09/cos333/beautiful.html
*
*
*
* Supports:
* ---------
* '.' Dot, matches any character
* '^' Start anchor, matches beginning of string
* '$' End anchor, matches end of string
* '*' Asterisk, match zero or more (greedy)
* '+' Plus, match one or more (greedy)
* '?' Question, match zero or one (non-greedy)
* '[abc]' Character class, match if one of {'a', 'b', 'c'}
* '[^abc]' Inverted class, match if NOT one of {'a', 'b', 'c'} -- NOTE: feature is currently broken!
* '[a-zA-Z]' Character ranges, the character set of the ranges { a-z | A-Z }
* '\s' Whitespace, \t \f \r \n \v and spaces
* '\S' Non-whitespace
* '\w' Alphanumeric, [a-zA-Z0-9_]
* '\W' Non-alphanumeric
* '\d' Digits, [0-9]
* '\D' Non-digits
*
*
*/
#include "re.h"
#include <stdio.h>
#include <ctype.h>
/* Definitions: */
enum { UNUSED, DOT, BEGIN, END, QUESTIONMARK, STAR, PLUS, CHAR_RE, CHAR_CLASS, INV_CHAR_CLASS, DIGIT, NOT_DIGIT, ALPHA, NOT_ALPHA, WHITESPACE, NOT_WHITESPACE, /* BRANCH */ };
/* Private function declarations: */
static int matchpattern(regex_t* pattern, const char* text, size_t text_length, size_t text_offset, size_t* matchlength);
static int matchcharclass(char c, const char* str);
static int matchstar(regex_t p, regex_t* pattern, const char* text, size_t text_length, size_t text_offset, size_t* matchlength);
static int matchplus(regex_t p, regex_t* pattern, const char* text, size_t text_length, size_t text_offset, size_t* matchlength);
static int matchone(regex_t p, char c);
static int matchdigit(char c);
static int matchalpha(char c);
static int matchwhitespace(char c);
static int matchmetachar(char c, const char* str);
static int matchrange(char c, const char* str);
static int matchdot(char c);
static int ismetachar(char c);
/* Public functions: */
int re_matchp(re_t pattern, const char* text, size_t text_length, size_t* matchlength)
{
*matchlength = 0;
if (pattern == 0 || text_length == 0) { return -1; }
if (pattern[0].type == BEGIN)
{
return ((matchpattern(&pattern[1], text, text_length, 0, matchlength)) ? 0 : -1);
}
size_t idx = -1;
do
{
idx += 1;
if (matchpattern(pattern, text, text_length, idx, matchlength))
{
return (int)idx;
}
}
while (idx < text_length);
return -1;
}
int re_compile(const char* pattern, size_t pattern_length, size_t max_regex_objects, size_t max_char_class_len, re_t* out_compiled, unsigned char** out_ccl)
{
if (out_compiled == NULL || out_ccl == NULL) { return 1; }
int ccl_bufidx = 1;
char c; /* current char in pattern */
int i = 0; /* index into pattern */
int j = 0; /* index into re_compiled */
while (i < (int)pattern_length && (j + 1 < MAX_REGEXP_OBJECTS))
{
c = pattern[i];
switch (c)
{
/* Meta-characters: */
case '^': { (*out_compiled)[j].type = BEGIN; } break;
case '$': { (*out_compiled)[j].type = END; } break;
case '.': { (*out_compiled)[j].type = DOT; } break;
case '*': { (*out_compiled)[j].type = STAR; } break;
case '+': { (*out_compiled)[j].type = PLUS; } break;
case '?': { (*out_compiled)[j].type = QUESTIONMARK; } break;
/* case '|': { re_compiled[j].type = BRANCH; } break; <-- not working properly */
/* Escaped character-classes (\s \w ...): */
case '\\':
{
if (i + 1 < (int)pattern_length)
{
/* Skip the escape-char '\\' */
i += 1;
/* ... and check the next */
switch (pattern[i])
{
/* Meta-character: */
case 'd': { (*out_compiled)[j].type = DIGIT; } break;
case 'D': { (*out_compiled)[j].type = NOT_DIGIT; } break;
case 'w': { (*out_compiled)[j].type = ALPHA; } break;
case 'W': { (*out_compiled)[j].type = NOT_ALPHA; } break;
case 's': { (*out_compiled)[j].type = WHITESPACE; } break;
case 'S': { (*out_compiled)[j].type = NOT_WHITESPACE; } break;
/* Escaped character, e.g. '.' or '$' */
default:
{
(*out_compiled)[j].type = CHAR_RE;
(*out_compiled)[j].u.ch = pattern[i];
} break;
}
}
else
{
(*out_compiled)[j].type = CHAR_RE;
(*out_compiled)[j].u.ch = pattern[i];
}
} break;
/* Character class: */
case '[':
{
/* Remember where the char-buffer starts. */
int buf_begin = ccl_bufidx;
/* Look-ahead to determine if negated */
if (pattern[i + 1] == '^')
{
(*out_compiled)[j].type = INV_CHAR_CLASS;
i += 1; /* Increment i to avoid including '^' in the char-buffer */
if (i + 1 == (int)pattern_length) /* incomplete pattern, missing non-zero char after '^' */
{
return 1;
}
}
else
{
(*out_compiled)[j].type = CHAR_CLASS;
}
/* Copy characters inside [..] to buffer */
while ((pattern[++i] != ']')
&& (i < (int)pattern_length)) /* Missing ] */
{
if (pattern[i] == '\\')
{
if (ccl_bufidx >= MAX_CHAR_CLASS_LEN - 1)
{
//fputs("exceeded internal buffer!\n", stderr);
return 1;
}
if (i + 1 == (int)pattern_length) /* incomplete pattern, missing non-zero char after '\\' */
{
return 1;
}
(*out_ccl)[ccl_bufidx++] = pattern[i++];
}
else if (ccl_bufidx >= MAX_CHAR_CLASS_LEN)
{
//fputs("exceeded internal buffer!\n", stderr);
return 1;
}
(*out_ccl)[ccl_bufidx++] = pattern[i];
}
if (ccl_bufidx >= MAX_CHAR_CLASS_LEN)
{
/* Catches cases such as [00000000000000000000000000000000000000][ */
//fputs("exceeded internal buffer!\n", stderr);
return 1;
}
/* Null-terminate string end */
(*out_ccl)[ccl_bufidx++] = 0;
(*out_compiled)[j].u.ccl = &(*out_ccl)[buf_begin];
} break;
/* Other characters: */
default:
{
(*out_compiled)[j].type = CHAR_RE;
(*out_compiled)[j].u.ch = c;
} break;
}
i += 1;
j += 1;
}
/* 'UNUSED' is a sentinel used to indicate end-of-pattern */
(*out_compiled)[j].type = UNUSED;
return 0; // ERROR_SUCCESS
}
void re_print(regex_t* pattern)
{
const char* types[] = { "UNUSED", "DOT", "BEGIN", "END", "QUESTIONMARK", "STAR", "PLUS", "CHAR", "CHAR_CLASS", "INV_CHAR_CLASS", "DIGIT", "NOT_DIGIT", "ALPHA", "NOT_ALPHA", "WHITESPACE", "NOT_WHITESPACE", "BRANCH" };
int i;
int j;
char c;
for (i = 0; i < MAX_REGEXP_OBJECTS; ++i)
{
if (pattern[i].type == UNUSED)
{
break;
}
printf("type: %s", types[pattern[i].type]);
if (pattern[i].type == CHAR_CLASS || pattern[i].type == INV_CHAR_CLASS)
{
printf(" [");
for (j = 0; j < MAX_CHAR_CLASS_LEN; ++j)
{
c = pattern[i].u.ccl[j];
if ((c == '\0') || (c == ']'))
{
break;
}
printf("%c", c);
}
printf("]");
}
else if (pattern[i].type == CHAR_RE)
{
printf(" '%c'", pattern[i].u.ch);
}
printf("\n");
}
}
/* Private functions: */
static int matchdigit(char c)
{
return isdigit(c);
}
static int matchalpha(char c)
{
return isalpha(c);
}
static int matchwhitespace(char c)
{
return isspace(c);
}
static int matchalphanum(char c)
{
return ((c == '_') || matchalpha(c) || matchdigit(c));
}
static int matchrange(char c, const char* str)
{
return ( (c != '-')
&& (str[0] != '\0')
&& (str[0] != '-')
&& (str[1] == '-')
&& (str[2] != '\0')
&& ( (c >= str[0])
&& (c <= str[2])));
}
static int matchdot(char c)
{
#if defined(RE_DOT_MATCHES_NEWLINE) && (RE_DOT_MATCHES_NEWLINE == 1)
(void)c;
return 1;
#else
return c != '\n' && c != '\r';
#endif
}
static int ismetachar(char c)
{
return ((c == 's') || (c == 'S') || (c == 'w') || (c == 'W') || (c == 'd') || (c == 'D'));
}
static int matchmetachar(char c, const char* str)
{
switch (str[0])
{
case 'd': return matchdigit(c);
case 'D': return !matchdigit(c);
case 'w': return matchalphanum(c);
case 'W': return !matchalphanum(c);
case 's': return matchwhitespace(c);
case 'S': return !matchwhitespace(c);
default: return (c == str[0]);
}
}
static int matchcharclass(char c, const char* str)
{
do
{
if (matchrange(c, str))
{
return 1;
}
else if (str[0] == '\\')
{
/* Escape-char: increment str-ptr and match on next char */
str += 1;
if (matchmetachar(c, str))
{
return 1;
}
else if ((c == str[0]) && !ismetachar(c))
{
return 1;
}
}
else if (c == str[0])
{
if (c == '-')
{
return ((str[-1] == '\0') || (str[1] == '\0'));
}
else
{
return 1;
}
}
}
while (*str++ != '\0');
return 0;
}
static int matchone(regex_t p, char c)
{
switch (p.type)
{
case DOT: return matchdot(c);
case CHAR_CLASS: return matchcharclass(c, (const char*)p.u.ccl);
case INV_CHAR_CLASS: return !matchcharclass(c, (const char*)p.u.ccl);
case DIGIT: return matchdigit(c);
case NOT_DIGIT: return !matchdigit(c);
case ALPHA: return matchalphanum(c);
case NOT_ALPHA: return !matchalphanum(c);
case WHITESPACE: return matchwhitespace(c);
case NOT_WHITESPACE: return !matchwhitespace(c);
default: return (p.u.ch == c);
}
}
static int matchstar(regex_t p, regex_t* pattern, const char* text, size_t text_length, size_t text_offset, size_t* matchlength)
{
size_t prelen = *matchlength;
const char* prepoint = text;
while ((text_offset < text_length) && matchone(p, text[text_offset]))
{
text_offset++;
(*matchlength)++;
}
while (&text[text_offset] >= prepoint)
{
if (matchpattern(pattern, text, text_length, text_offset--, matchlength))
return 1;
(*matchlength)--;
}
*matchlength = prelen;
return 0;
}
static int matchplus(regex_t p, regex_t* pattern, const char* text, size_t text_length, size_t text_offset, size_t* matchlength)
{
const char* prepoint = text;
while ((text_offset < text_length) && matchone(p, text[text_offset]))
{
text_offset++;
(*matchlength)++;
}
while (text > prepoint)
{
if (matchpattern(pattern, text, text_length, text_offset--, matchlength))
return 1;
(*matchlength)--;
}
return 0;
}
static int matchquestion(regex_t p, regex_t* pattern, const char* text, size_t text_length, size_t text_offset, size_t* matchlength)
{
if (p.type == UNUSED)
return 1;
if (matchpattern(pattern, text, text_length, text_offset, matchlength))
return 1;
if ((text_offset < text_length) && matchone(p, text[text_offset++]))
{
if (matchpattern(pattern, text, text_length, text_offset, matchlength))
{
(*matchlength)++;
return 1;
}
}
return 0;
}
#if 0
/* Recursive matching */
static int matchpattern(regex_t* pattern, const char* text, int *matchlength)
{
int pre = *matchlength;
if ((pattern[0].type == UNUSED) || (pattern[1].type == QUESTIONMARK))
{
return matchquestion(pattern[1], &pattern[2], text, matchlength);
}
else if (pattern[1].type == STAR)
{
return matchstar(pattern[0], &pattern[2], text, matchlength);
}
else if (pattern[1].type == PLUS)
{
return matchplus(pattern[0], &pattern[2], text, matchlength);
}
else if ((pattern[0].type == END) && pattern[1].type == UNUSED)
{
return text[0] == '\0';
}
else if ((text[0] != '\0') && matchone(pattern[0], text[0]))
{
(*matchlength)++;
return matchpattern(&pattern[1], text+1);
}
else
{
*matchlength = pre;
return 0;
}
}
#else
/* Iterative matching */
static int matchpattern(regex_t* pattern, const char* text, size_t text_length, size_t text_offset, size_t* matchlength)
{
size_t pre = *matchlength;
do
{
if ((pattern[0].type == UNUSED) || (pattern[1].type == QUESTIONMARK))
{
return matchquestion(pattern[0], &pattern[2], text, text_length, text_offset, matchlength);
}
else if (pattern[1].type == STAR)
{
return matchstar(pattern[0], &pattern[2], text, text_length, text_offset, matchlength);
}
else if (pattern[1].type == PLUS)
{
return matchplus(pattern[0], &pattern[2], text, text_length, text_offset, matchlength);
}
else if ((pattern[0].type == END) && pattern[1].type == UNUSED)
{
return (text_offset == text_length - 1);
}
/* Branching is not working properly
else if (pattern[1].type == BRANCH)
{
return (matchpattern(pattern, text) || matchpattern(&pattern[2], text));
}
*/
(*matchlength)++;
}
while ((text_offset < text_length) && matchone(*pattern++, text[text_offset++]));
*matchlength = pre;
return 0;
}
#endif