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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>
-
- typedef struct {
- int in;
- char input;
- int to;
- } delta_t;
-
- typedef struct {
- int in;
- int to;
- } offshoot_t;
-
- #define HALT_AND_CATCH_FIRE -1
-
- #define HOOK_ALL(from, str, to) do { \
- for (char * s = str; *s != '\00'; s++) { \
- vector_push(®ex->delta_table, \
- &(delta_t){state + from, *s, state + to} \
- ); \
- } \
- if (do_catch) { \
- vector_push(®ex->catch_table, \
- &(offshoot_t){state + from, state + to} \
- ); \
- } \
- } while (0)
-
- #define EAT(n) do { \
- s += n; \
- } while (0)
-
- 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;
- }
-
-
- static int escape_1_to_1(const char c, char * whitelist) {
- switch(c) {
- case 't': {
- strcat(whitelist, "\t");
- } return 1;
- case 'n': {
- strcat(whitelist, "\n");
- } return 1;
- case 'r': {
- strcat(whitelist, "\r");
- } return 1;
- case 'b': {
- strcat(whitelist, "\b");
- } return 1;
- case '[': {
- strcat(whitelist, "[");
- } return 1;
- case ']': {
- strcat(whitelist, "]");
- } return 1;
- case '.': {
- strcat(whitelist, ".");
- } return 1;
- case '?': {
- strcat(whitelist, "?");
- } return 1;
- case '+': {
- strcat(whitelist, "+");
- } return 1;
- case '*': {
- strcat(whitelist, "*");
- } return 1;
- case '\\': {
- strcat(whitelist, "\\");
- } return 1;
- }
-
- return 0;
- }
-
- static int escape_1_to_N(const char c, char * 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(whitelist, 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(whitelist, 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(whitelist, 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(whitelist, keyword_chars);
- return sizeof(keyword_chars)-1;
- };
- case 'f': {
- const char filename_chars[] = "@0123456789/.-_+,#$%~=";
- strcpy(whitelist, filename_chars);
- return sizeof(filename_chars)-1;
- };
- case 'F': {
- const char filename_chars[] = "@/.-_+,#$%~=";
- strcpy(whitelist, 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(whitelist, 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(whitelist, printable_chars);
- return sizeof(printable_chars)-1;
- };
- case 's': {
- const char whitespace_chars[] = " \t\v\n";
- strcpy(whitelist, whitespace_chars);
- return sizeof(whitespace_chars)-1;
- };
- case 'd': {
- const char digit_chars[] = "0123456789";
- strcpy(whitelist, digit_chars);
- return sizeof(digit_chars)-1;
- };
- case 'x': {
- const char hex_chars[] = "0123456789abcdefABCDEF";
- strcpy(whitelist, hex_chars);
- return sizeof(hex_chars)-1;
- };
- case 'o': {
- const char oct_chars[] = "01234567";
- strcpy(whitelist, oct_chars);
- return sizeof(oct_chars)-1;
- };
- case 'w': {
- const char word_chars[] = "0123456789abcdefghijklmnopqrstuwxyzABCDEFGHIJKLMNOPQRSTUWXYZ_";
- strcpy(whitelist, word_chars);
- return sizeof(word_chars)-1;
- };
- case 'h': {
- const char very_word_chars[] = "abcdefghijklmnopqrstuwxyzABCDEFGHIJKLMNOPQRSTUWXYZ_";
- strcpy(whitelist, very_word_chars);
- return sizeof(very_word_chars)-1;
- };
- case 'a': {
- const char alpha_chars[] = "abcdefghijklmnopqrstuwxyzABCDEFGHIJKLMNOPQRSTUWXYZ";
- strcpy(whitelist, alpha_chars);
- return sizeof(alpha_chars)-1;
- };
- case 'l': {
- const char lower_alpha_chars[] = "abcdefghijklmnopqrstuwxyz";
- strcpy(whitelist, lower_alpha_chars);
- return sizeof(lower_alpha_chars)-1;
- };
- case 'u': {
- const char upper_alpha_chars[] = "ABCDEFGHIJKLMNOPQRSTUWXYZ";
- strcpy(whitelist, upper_alpha_chars);
- return sizeof(upper_alpha_chars)-1;
- };
- }
-
- return 0;
- }
-
- static int compile_range(const char * const range,
- char * whitelist) {
- assert(range[0] == '[' && "Not a range.");
-
- int r = 0;
- const char * s;
- for (s = range+1; *s != ']'; s++) {
- assert(*s != '\00' && "Unclosed range.");
- char c = *s;
- if (escape_1_to_1(c, whitelist)
- || escape_1_to_N(c, whitelist)) {
- ;
- } else if (*(s+1) == '-') {
- char end = *(s+2);
- assert(c < end && "Endless range.");
- for (char cc = c; cc < end+1; cc++) {
- strncat(whitelist, &cc, 1);
- strncat(whitelist, "\00", 1);
- }
- s += 2;
- } else {
- ++r;
- strncat(whitelist, &c, 1);
- strncat(whitelist, "\00", 1);
- }
- }
-
- return ((s - range) + 1);
- }
-
- regex_t * regex_compile(const char * const pattern) {
- regex_t * regex = (regex_t *)malloc(sizeof(regex_t));
- regex->str = strdup(pattern);
- vector_init(®ex->delta_table, sizeof(delta_t), 32);
- vector_init(®ex->catch_table, sizeof(offshoot_t), 16);
-
- int state = 0;
-
- char whitelist[64];
- bool do_catch;
- for (const char * s = pattern; *s != '\00';) {
- // Get token
- assert(!is_quantifier(*pattern) && "Pattern starts with quantifier.");
- whitelist[0] = '\00';
- do_catch = false;
- switch (*s) {
- case '.': {
- do_catch = true;
- } break;
- case '\\': {
- EAT(1);
- if(escape_1_to_1(*s, whitelist)
- || escape_1_to_N(*s, whitelist)){
- ;
- } else {
- assert(!"Unknown escape.");
- }
- } break;
- case '[': {
- EAT(compile_range(s, whitelist)-1);
- } break;
- default: {
- whitelist[0] = *s;
- whitelist[1] = '\00';
- } break;
- }
-
- EAT(1);
-
- // Quantifier
- switch (*s) {
- case '?': {
- HOOK_ALL(0, whitelist, +1);
- EAT(1);
- } break;
- case '*': {
- HOOK_ALL(0, whitelist, 0);
- EAT(1);
- } break;
- case '+': {
- HOOK_ALL(0, whitelist, +1);
- state += 1;
- HOOK_ALL(0, whitelist, 0);
- EAT(1);
- } break;
- default: { // Literal
- HOOK_ALL(0, whitelist, +1);
- state += 1;
- } break;
- }
- }
-
- regex->accepting_state = state;
-
- return regex;
- }
-
- int regex_free(regex_t * const regex) {
- free(regex->str);
- vector_free(®ex->delta_table);
- vector_free(®ex->catch_table);
- free(regex);
- return 0;
- }
-
- bool catch_(const regex_t * const regex,
- int * const state) {
-
- for (int i = 0; i < regex->catch_table.element_size; i++){
- const offshoot_t * const offshoot = (vector_get(®ex->catch_table, i));
- if (offshoot->in == *state) {
- *state = offshoot->to;
- return true;
- }
- }
- return false;
- }
-
- bool regex_assert(const regex_t * const regex,
- const char * const string,
- int state) {
-
- for (const char * s = string; *s != '\00'; s++) {
- // delta
- for (int i = 0; i < regex->delta_table.element_count; i++) {
- const delta_t * const delta = (delta_t *)(vector_get(®ex->delta_table, i));
- if ((delta->in == state)
- && (delta->input == *s)) {
- if(regex_assert(regex, s+1, delta->to)){
- return true;
- }
- }
- }
-
- if (catch_(regex, &state)) {
- continue;
- }
-
- return false;
- }
-
- return (state == regex->accepting_state);
- }
-
- bool regex_search( regex_t * regex,
- const char * const string) {
-
- if (regex == NULL) {
- return false;
- }
- if (string == NULL) {
- return true;
- }
-
- return regex_assert(regex, string, 0);
- }
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