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