82 lines
1.9 KiB
C
82 lines
1.9 KiB
C
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#include <stddef.h>
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#include <misc/debug.h>
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static void build_substring_backtrack_table (const char *str, size_t len, size_t *out_table)
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{
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ASSERT(len > 0)
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size_t x = 0;
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for (size_t i = 1; i < len; i++) {
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out_table[i] = x;
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while (x > 0 && str[i] != str[x]) {
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x = out_table[x];
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}
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if (str[i] == str[x]) {
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x++;
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}
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}
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}
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static int find_substring (const char *text, size_t text_len, const char *word, size_t word_len, const size_t *table, size_t *out_position)
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{
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ASSERT(word_len > 0)
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size_t x = 0;
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for (size_t i = 0; i < text_len; i++) {
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while (x > 0 && text[i] != word[x]) {
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x = table[x];
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}
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if (text[i] == word[x]) {
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if (x + 1 == word_len) {
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*out_position = i - x;
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return 1;
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}
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x++;
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}
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}
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return 0;
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}
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static void build_substring_backtrack_table_reverse (const char *str, size_t len, size_t *out_table)
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{
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ASSERT(len > 0)
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size_t x = 0;
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for (size_t i = 1; i < len; i++) {
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out_table[i] = x;
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while (x > 0 && str[len - 1 - i] != str[len - 1 - x]) {
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x = out_table[x];
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}
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if (str[len - 1 - i] == str[len - 1 - x]) {
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x++;
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}
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}
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}
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static int find_substring_reverse (const char *text, size_t text_len, const char *word, size_t word_len, const size_t *table, size_t *out_position)
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{
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ASSERT(word_len > 0)
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size_t x = 0;
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for (size_t i = 0; i < text_len; i++) {
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while (x > 0 && text[text_len - 1 - i] != word[word_len - 1 - x]) {
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x = table[x];
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}
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if (text[text_len - 1 - i] == word[word_len - 1 - x]) {
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if (x + 1 == word_len) {
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*out_position = (text_len - 1 - i);
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return 1;
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}
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x++;
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}
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}
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return 0;
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}
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