systemSetup

match.c (6023B)

---

 #include <ctype.h>
 #include <string.h>
 #include <strings.h>
 #include <stdio.h>
 #include <float.h>
 #include <math.h>
 #include <stdlib.h>
 
 #include "match.h"
 #include "bonus.h"
 
 #include "config.h"
 
 char *strcasechr(const char *s, char c) {
 	const char accept[3] = {c, toupper(c), 0};
 	return strpbrk(s, accept);
 }
 
 int has_match(const char *needle, const char *haystack) {
 	while (*needle) {
 		char nch = *needle++;
 
 		if (!(haystack = strcasechr(haystack, nch))) {
 			return 0;
 		}
 		haystack++;
 	}
 	return 1;
 }
 
 #define SWAP(x, y, T) do { T SWAP = x; x = y; y = SWAP; } while (0)
 
 #define max(a, b) (((a) > (b)) ? (a) : (b))
 
 struct match_struct {
 	int needle_len;
 	int haystack_len;
 
 	char lower_needle[MATCH_MAX_LEN];
 	char lower_haystack[MATCH_MAX_LEN];
 
 	score_t match_bonus[MATCH_MAX_LEN];
 };
 
 static void precompute_bonus(const char *haystack, score_t *match_bonus) {
 	/* Which positions are beginning of words */
 	char last_ch = '/';
 	for (int i = 0; haystack[i]; i++) {
 		char ch = haystack[i];
 		match_bonus[i] = COMPUTE_BONUS(last_ch, ch);
 		last_ch = ch;
 	}
 }
 
 static void setup_match_struct(struct match_struct *match, const char *needle, const char *haystack) {
 	match->needle_len = strlen(needle);
 	match->haystack_len = strlen(haystack);
 
 	if (match->haystack_len > MATCH_MAX_LEN || match->needle_len > match->haystack_len) {
 		return;
 	}
 
 	for (int i = 0; i < match->needle_len; i++)
 		match->lower_needle[i] = tolower(needle[i]);
 
 	for (int i = 0; i < match->haystack_len; i++)
 		match->lower_haystack[i] = tolower(haystack[i]);
 
 	precompute_bonus(haystack, match->match_bonus);
 }
 
 static inline void match_row(const struct match_struct *match, int row, score_t *curr_D, score_t *curr_M, const score_t *last_D, const score_t *last_M) {
 	int n = match->needle_len;
 	int m = match->haystack_len;
 	int i = row;
 
 	const char *lower_needle = match->lower_needle;
 	const char *lower_haystack = match->lower_haystack;
 	const score_t *match_bonus = match->match_bonus;
 
 	score_t prev_score = SCORE_MIN;
 	score_t gap_score = i == n - 1 ? SCORE_GAP_TRAILING : SCORE_GAP_INNER;
 
 	for (int j = 0; j < m; j++) {
 		if (lower_needle[i] == lower_haystack[j]) {
 			score_t score = SCORE_MIN;
 			if (!i) {
 				score = (j * SCORE_GAP_LEADING) + match_bonus[j];
 			} else if (j) { /* i > 0 && j > 0*/
 				score = max(
 						last_M[j - 1] + match_bonus[j],
 
 						/* consecutive match, doesn't stack with match_bonus */
 						last_D[j - 1] + SCORE_MATCH_CONSECUTIVE);
 			}
 			curr_D[j] = score;
 			curr_M[j] = prev_score = max(score, prev_score + gap_score);
 		} else {
 			curr_D[j] = SCORE_MIN;
 			curr_M[j] = prev_score = prev_score + gap_score;
 		}
 	}
 }
 
 score_t match(const char *needle, const char *haystack) {
 	if (!*needle)
 		return SCORE_MIN;
 
 	struct match_struct match;
 	setup_match_struct(&match, needle, haystack);
 
 	int n = match.needle_len;
 	int m = match.haystack_len;
 
 	if (m > MATCH_MAX_LEN || n > m) {
 		/*
 		 * Unreasonably large candidate: return no score
 		 * If it is a valid match it will still be returned, it will
 		 * just be ranked below any reasonably sized candidates
 		 */
 		return SCORE_MIN;
 	} else if (n == m) {
 		/* Since this method can only be called with a haystack which
 		 * matches needle. If the lengths of the strings are equal the
 		 * strings themselves must also be equal (ignoring case).
 		 */
 		return SCORE_MAX;
 	}
 
 	/*
 	 * D[][] Stores the best score for this position ending with a match.
 	 * M[][] Stores the best possible score at this position.
 	 */
 	score_t D[2][MATCH_MAX_LEN], M[2][MATCH_MAX_LEN];
 
 	score_t *last_D, *last_M;
 	score_t *curr_D, *curr_M;
 
 	last_D = D[0];
 	last_M = M[0];
 	curr_D = D[1];
 	curr_M = M[1];
 
 	for (int i = 0; i < n; i++) {
 		match_row(&match, i, curr_D, curr_M, last_D, last_M);
 
 		SWAP(curr_D, last_D, score_t *);
 		SWAP(curr_M, last_M, score_t *);
 	}
 
 	return last_M[m - 1];
 }
 
 score_t match_positions(const char *needle, const char *haystack, size_t *positions) {
 	if (!*needle)
 		return SCORE_MIN;
 
 	struct match_struct match;
 	setup_match_struct(&match, needle, haystack);
 
 	int n = match.needle_len;
 	int m = match.haystack_len;
 
 	if (m > MATCH_MAX_LEN || n > m) {
 		/*
 		 * Unreasonably large candidate: return no score
 		 * If it is a valid match it will still be returned, it will
 		 * just be ranked below any reasonably sized candidates
 		 */
 		return SCORE_MIN;
 	} else if (n == m) {
 		/* Since this method can only be called with a haystack which
 		 * matches needle. If the lengths of the strings are equal the
 		 * strings themselves must also be equal (ignoring case).
 		 */
 		if (positions)
 			for (int i = 0; i < n; i++)
 				positions[i] = i;
 		return SCORE_MAX;
 	}
 
 	/*
 	 * D[][] Stores the best score for this position ending with a match.
 	 * M[][] Stores the best possible score at this position.
 	 */
 	score_t (*D)[MATCH_MAX_LEN], (*M)[MATCH_MAX_LEN];
 	M = malloc(sizeof(score_t) * MATCH_MAX_LEN * n);
 	D = malloc(sizeof(score_t) * MATCH_MAX_LEN * n);
 
 	score_t *last_D, *last_M;
 	score_t *curr_D, *curr_M;
 
 	for (int i = 0; i < n; i++) {
 		curr_D = &D[i][0];
 		curr_M = &M[i][0];
 
 		match_row(&match, i, curr_D, curr_M, last_D, last_M);
 
 		last_D = curr_D;
 		last_M = curr_M;
 	}
 
 	/* backtrace to find the positions of optimal matching */
 	if (positions) {
 		int match_required = 0;
 		for (int i = n - 1, j = m - 1; i >= 0; i--) {
 			for (; j >= 0; j--) {
 				/*
 				 * There may be multiple paths which result in
 				 * the optimal weight.
 				 *
 				 * For simplicity, we will pick the first one
 				 * we encounter, the latest in the candidate
 				 * string.
 				 */
 				if (D[i][j] != SCORE_MIN &&
 				    (match_required || D[i][j] == M[i][j])) {
 					/* If this score was determined using
 					 * SCORE_MATCH_CONSECUTIVE, the
 					 * previous character MUST be a match
 					 */
 					match_required =
 					    i && j &&
 					    M[i][j] == D[i - 1][j - 1] + SCORE_MATCH_CONSECUTIVE;
 					positions[i] = j--;
 					break;
 				}
 			}
 		}
 	}
 
 	score_t result = M[n - 1][m - 1];
 
 	free(M);
 	free(D);
 
 	return result;
 }