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libhl/source/regex.c

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/* regex.c
* Copyright 2023 Anon Anonson, Ognjen 'xolatile' Milan Robovic, Emil Williams
* SPDX Identifier: GPL-3.0-only / NO WARRANTY / NO GUARANTEE */
#include "regex.h"
#include <assert.h>
#include <string.h>
#include <limits.h>
// ------------------
// ### Char tests ###
// ------------------
static bool is_quantifier(const char c) {
for (const char * s = "+*?="; *s != '\00'; s++) {
if (*s == c) {
return true;
}
}
return false;
}
bool is_magic(const char c) {
if (is_quantifier(c)) {
return true;
}
for (const char * s = "\\[]"; *s != '\00'; s++) {
if (*s == c) {
return true;
}
}
return false;
}
// ----------------------
// ### Internal Types ###
// ----------------------
typedef struct {
int in;
char input;
int to;
int width;
} delta_t;
typedef struct {
int in;
int to;
} offshoot_t;
typedef struct {
bool * do_catch;
bool * is_negative;
int * state;
int * width;
char * whitelist;
char * blacklist;
regex_t * regex;
} compiler_state;
// ----------------------------------
// ### Regex creation/destruction ###
// ----------------------------------
static int escape_1_to_1(const char c, compiler_state * cs) {
char * target_list = (*cs->is_negative) ? cs->blacklist : cs->whitelist;
switch (c) {
case 't': {
strcat(target_list, "\t");
} return 1;
case 'n': {
strcat(target_list, "\n");
} return 1;
case 'r': {
strcat(target_list, "\r");
} return 1;
case 'b': {
strcat(target_list, "\b");
} return 1;
case '[': {
strcat(target_list, "[");
} return 1;
case ']': {
strcat(target_list, "]");
} return 1;
case '.': {
strcat(target_list, ".");
} return 1;
case '=': {
strcat(target_list, "=");
} return 1;
case '?': {
strcat(target_list, "?");
} return 1;
case '+': {
strcat(target_list, "+");
} return 1;
case '*': {
strcat(target_list, "*");
} return 1;
case '\\': {
strcat(target_list, "\\");
} return 1;
}
return 0;
}
static int escape_1_to_N(const char c, compiler_state * cs) {
char * target_list = (*cs->is_negative) ? cs->blacklist : cs->whitelist;
switch(c) {
case 'i': {
const char identifier_chars[] = "@0123456789_"
"\300\301\302\303\304"
"\305\306\307\310\311"
"\312\313\314\315\316"
"\317\320\321\322\323"
"\324\325\326\327\330"
"\331\332\333\334\335"
"\336\337";
strcpy(target_list, identifier_chars);
return sizeof(identifier_chars)-1;
};
case 'I': {
const char identifier_chars[] = "@_"
"\300\301\302\303\304"
"\305\306\307\310\311"
"\312\313\314\315\316"
"\317\320\321\322\323"
"\324\325\326\327\330"
"\331\332\333\334\335"
"\336\337";
strcpy(target_list, identifier_chars);
return sizeof(identifier_chars)-1;
};
case 'k': {
const char keyword_chars[] = "@0123456789_"
"\300\301\302\303\304"
"\305\306\307\310\311"
"\312\313\314\315\316"
"\317\320\321\322\323"
"\324\325\326\327\330"
"\331\332\333\334\335"
"\336\337";
strcpy(target_list, keyword_chars);
return sizeof(keyword_chars)-1;
};
case 'K': {
const char keyword_chars[] = "@_"
"\300\301\302\303\304"
"\305\306\307\310\311"
"\312\313\314\315\316"
"\317\320\321\322\323"
"\324\325\326\327\330"
"\331\332\333\334\335"
"\336\337";
strcpy(target_list, keyword_chars);
return sizeof(keyword_chars)-1;
};
case 'f': {
const char filename_chars[] = "@0123456789/.-_+,#$%~=";
strcpy(target_list, filename_chars);
return sizeof(filename_chars)-1;
};
case 'F': {
const char filename_chars[] = "@/.-_+,#$%~=";
strcpy(target_list, filename_chars);
return sizeof(filename_chars)-1;
};
case 'p': {
const char printable_chars[] = "@"
"\241\242\243\244\245"
"\246\247\250\251\252"
"\253\254\255\256\257"
"\260\261\262\263\264"
"\265\266\267\270\271"
"\272\273\274\275\276"
"\277"
"\300\301\302\303\304"
"\305\306\307\310\311"
"\312\313\314\315\316"
"\317\320\321\322\323"
"\324\325\326\327\330"
"\331\332\333\334\335"
"\336\337";
strcpy(target_list, printable_chars);
return sizeof(printable_chars)-1;
};
case 'P': {
const char printable_chars[] = "@"
"\241\242\243\244\245"
"\246\247\250\251\252"
"\253\254\255\256\257"
"\260\261\262\263\264"
"\265\266\267\270\271"
"\272\273\274\275\276"
"\277"
"\300\301\302\303\304"
"\305\306\307\310\311"
"\312\313\314\315\316"
"\317\320\321\322\323"
"\324\325\326\327\330"
"\331\332\333\334\335"
"\336\337";
strcpy(target_list, printable_chars);
return sizeof(printable_chars)-1;
};
case 's': {
const char whitespace_chars[] = " \t\v\n";
strcpy(target_list, whitespace_chars);
return sizeof(whitespace_chars)-1;
};
case 'd': {
const char digit_chars[] = "0123456789";
strcpy(target_list, digit_chars);
return sizeof(digit_chars)-1;
};
case 'x': {
const char hex_chars[] = "0123456789"
"abcdef"
"ABCDEF";
strcpy(target_list, hex_chars);
return sizeof(hex_chars)-1;
};
case 'o': {
const char oct_chars[] = "01234567";
strcpy(target_list, oct_chars);
return sizeof(oct_chars)-1;
};
case 'w': {
const char word_chars[] = "0123456789"
"abcdefghijklmnopqrstuwxyz"
"ABCDEFGHIJKLMNOPQRSTUWXYZ"
"_";
strcpy(target_list, word_chars);
return sizeof(word_chars)-1;
};
case 'h': {
const char very_word_chars[] = "abcdefghijklmnopqrstuwxyz"
"ABCDEFGHIJKLMNOPQRSTUWXYZ"
"_";
strcpy(target_list, very_word_chars);
return sizeof(very_word_chars)-1;
};
case 'a': {
const char alpha_chars[] = "abcdefghijklmnopqrstuwxyz"
"ABCDEFGHIJKLMNOPQRSTUWXYZ";
strcpy(target_list, alpha_chars);
return sizeof(alpha_chars)-1;
};
case 'l': {
const char lower_alpha_chars[] = "abcdefghijklmnopqrstuwxyz";
strcpy(target_list, lower_alpha_chars);
return sizeof(lower_alpha_chars)-1;
};
case 'u': {
const char upper_alpha_chars[] = "ABCDEFGHIJKLMNOPQRSTUWXYZ";
strcpy(target_list, upper_alpha_chars);
return sizeof(upper_alpha_chars)-1;
};
}
return 0;
}
//static int compile_hologram(char * hologram, char * whitelist) {
// if (hologram[0] == '\\') {
// switch (hologram[1]) {
// case '<': {
// const char very_word_chars[] = "abcdefghijklmnopqrstuwxyz"
// "ABCDEFGHIJKLMNOPQRSTUWXYZ"
// "_";
// strcat(whitelist, very_word_chars);
// is_negative = true;
// HOOK_ALL(0, whitelist, 0)
// } break;
// }
// }
//}
static int compile_range(const char * const range,
char * whitelist,
bool * is_negative) {
assert((range[0] == '[') && "Not a range.");
const char * s;
if (range[1] == '^') {
*is_negative = true;
s = range + 2;
} else {
s = range + 1;
}
for (; *s != ']'; s++) {
assert((*s != '\0') && "Unclosed range.");
char c = *s;
if (c == '\\') {
s += 1;
assert(compile_escape(*s, cs) && "Unknown escape.");
} else if (*(s+1) == '-') {
char end = *(s+2);
assert((c < end) && "Endless range.");
for (char cc = c; cc < end+1; cc++) {
strncat(target_list, &cc, 1);
strncat(target_list, "\0", 1);
}
s += 2;
} else {
strncat(target_list, &c, 1);
}
}
return ((s - range) + 1);
}
void filter_blacklist(const char * const whitelist,
const char * const blacklist,
char * const filtered) {
for (char * black_pointer = blacklist; *black_pointer != '\0'; black_pointer++) {
for(char * white_pointer = blacklist; *white_pointer != '\0'; white_pointer++) {
if (*black_pointer == *white_pointer) {
goto long_continue;
}
}
strncat(filtered, black_pointer, 1);
long_continue:
}
}
#define HALT_AND_CATCH_FIRE INT_MIN
void HOOK_ALL( int from,
const char * const str,
int to,
compiler_state * cs) {
int hook_to = (to == HALT_AND_CATCH_FIRE) ? -1 : ((*cs->state) + to);
for (const char * s = str; *s != '\0'; s++) {
delta_t * delta = malloc(sizeof(delta_t));
delta->in = *cs->state + from;
delta->input = *s;
delta->to = hook_to;
delta->width = *cs->width;
vector_push(&cs->regex->delta_table,
&delta);
}
}
void OFFSHOOT(int from,
int to,
compiler_state * cs) {
offshoot_t * offshoot = malloc(sizeof(offshoot_t));
offshoot->in = *cs->state + from;
offshoot->to = *cs->state + to;
vector_push(&cs->regex->catch_table,
&offshoot);
}
regex_t * regex_compile(const char * const pattern) {
regex_t * regex = (regex_t *)malloc(sizeof(regex_t));
regex->str = strdup(pattern);
vector_init(&regex->delta_table, sizeof(delta_t*), 0UL);
vector_init(&regex->catch_table, sizeof(offshoot_t*), 0UL);
int state = 0;
bool do_catch;
bool is_negative;
int width;
char whitelist[64];
char blacklist[64];
compiler_state cs = {
.do_catch = &do_catch,
.is_negative = &is_negative,
.state = &state,
.width = &width,
.whitelist = whitelist,
.blacklist = blacklist,
.regex = regex,
};
for (const char * s = pattern; *s != '\00';) {
// Reset the compiler
assert(!is_quantifier(*pattern) && "Pattern starts with quantifier.");
whitelist[0] = '\00';
blacklist[0] = '\00';
do_catch = false;
is_negative = false;
width = 1;
// Translate char
switch (*s) {
case '.': {
compile_dot(&cs);
} break;
case '\\': {
s += 1;
assert(compile_escape(*s, &cs) && "Unknown escape.");
} break;
case '[': {
s += compile_range(s, &cs) - 1;
} break;
default: {
whitelist[0] = *s;
whitelist[1] = '\00';
} break;
}
s += 1;
// Compile with quantifier
switch (*s) {
case '=':
case '?': {
HOOK_ALL(0, whitelist, +1, &cs);
if (do_catch || is_negative) {
OFFSHOOT(0, +1, &cs);
}
s += 1;
} break;
case '*': {
HOOK_ALL(0, whitelist, 0, &cs);
if (do_catch) {
OFFSHOOT(0, +1, &cs);
} else if (is_negative) {
OFFSHOOT(0, 0, &cs);
}
s += 1;
} break;
case '+': {
HOOK_ALL(0, whitelist, +1, &cs);
if (do_catch || is_negative) {
OFFSHOOT(0, +1, &cs);
}
state += 1;
HOOK_ALL(0, whitelist, 0, &cs);
if (do_catch || is_negative) {
OFFSHOOT(0, 0, &cs);
}
s += 1;
} break;
default: { // Literal
HOOK_ALL(0, whitelist, +1, &cs);
if (do_catch || is_negative) {
OFFSHOOT(0, +1, &cs);
}
state += 1;
} break;
}
// Compile blacklist
if (*blacklist) {
char filtered_blacklist[64];
filtered_blacklist[0] = '\0';
filter_blacklist(whitelist, blacklist, filtered_blacklist);
HOOK_ALL(0, filtered_blacklist, HALT_AND_CATCH_FIRE, &cs);
}
}
regex->accepting_state = state;
return regex;
}
int regex_free(regex_t * const regex) {
free(regex->str);
vector_free(&regex->delta_table);
vector_free(&regex->catch_table);
free(regex);
return 0;
}
// -----------------
// ### Searching ###
// -----------------
static bool catch_(const regex_t * const regex,
int * const state) {
for (size_t i = 0; i < regex->catch_table.element_count; i++){
const offshoot_t * const offshoot = *(offshoot_t**)vector_get(&regex->catch_table, i);
if (offshoot->in == *state) {
*state = offshoot->to;
return true;
}
}
return false;
}
static int regex_assert(const regex_t * const regex,
const char * const string,
int state,
int * width) {
for (const char * s = string; *s != '\00'; s++) {
// delta
for (size_t i = 0; i < regex->delta_table.element_count; i++) {
const delta_t * const delta = *(delta_t**)vector_get(&regex->delta_table, i);
if ((delta->in == state)
&& (delta->input == *s)) {
int r = regex_assert(regex, s + delta->width, delta->to, width + 1);
if(r){
return r;
}
}
}
if (catch_(regex, &state)) {
continue;
}
return (state == regex->accepting_state) ? width : false;
}
return false;
}
int regex_match( regex_t * regex,
const char * const string) {
if (regex == NULL) {
return false;
}
if (string == NULL) {
return true;
}
return regex_assert(regex, string, 0, 0);
}
bool regex_search( regex_t * regex,
const char * const string) {
return (bool)regex_match(regex, string);
}
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