Create fuzzy scoring and fuzzy sort.

inc/utils.h

@@ -22,6 +22,11 @@
 
 #include <sys/types.h>
 
+typedef double score_t;
+#define SCORE_MAX INFINITY
+#define SCORE_MIN -INFINITY
+#define MATCH_FUZZY_MAX_LEN 256
+
 time_t utils_get_time_millis(void);
 
 void utils_sleep_millis(time_t millis);
@@ -34,6 +39,8 @@ size_t utils_min3(size_t n1, size_t n2, size_t n3);
 
 size_t utils_distance(const char* haystack, const char* needle);
 
+score_t utils_fuzzy_score(const char *haystack, const char *needle);
+
 void utils_mkdir(char *path, mode_t mode);
 
 #endif

src/utils.c

@@ -17,13 +17,15 @@
 
 #include <utils.h>
 
+#include <ctype.h>
+#include <libgen.h>
 #include <math.h>
 #include <stdarg.h>
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <libgen.h>
 
 #include <sys/stat.h>
 #include <sys/time.h>
@@ -109,6 +111,179 @@ size_t utils_distance(const char* haystack, const char* needle) {
 	return arr[str1_len][str2_len];
 }
 
+// leading gap
+#define SCORE_GAP_LEADING -0.005
+// trailing gap
+#define SCORE_GAP_TRAILING -0.005
+// gap in the middle
+#define SCORE_GAP_INNER -0.01
+// we matched the characters consecutively
+#define SCORE_MATCH_CONSECUTIVE 1.0
+// we got a consecutive match, but insensitive is on
+// and we didn't match the case.
+#define SCORE_MATCH_NOT_MATCH_CASE 0.9
+// we are matching after a slash
+#define SCORE_MATCH_SLASH 0.9
+// we are matching after a space dash or hyphen
+#define SCORE_MATCH_WORD 0.8
+// we are matching a camel case letter
+#define SCORE_MATCH_CAPITAL 0.7
+// we are matching after a dot
+#define SCORE_MATCH_DOT 0.6
+
+#define SWAP(x, y, T)													\
+	do {																\
+		T SWAP = x;														\
+		x = y;															\
+		y = SWAP;														\
+  } while (0)
+
+#define max(a, b) (((a) > (b)) ? (a) : (b))
+
+static void precompute_bonus(const char *haystack, score_t *match_bonus) {
+	/* Which positions are beginning of words */
+	int m = strlen(haystack);
+	char last_ch = '\0';
+	for (int i = 0; i < m; i++) {
+		char ch = haystack[i];
+
+		score_t score = 0;
+		if (isalnum(ch)) {
+			if (!last_ch || last_ch == '/') {
+				score = SCORE_MATCH_SLASH;
+			} else if (last_ch == '-' || last_ch == '_' ||
+					   last_ch == ' ') {
+				score = SCORE_MATCH_WORD;
+			} else if (last_ch >= 'a' && last_ch <= 'z' &&
+					   ch >= 'A' && ch <= 'Z') {
+				/* CamelCase */
+				score = SCORE_MATCH_CAPITAL;
+			} else if (last_ch == '.') {
+				score = SCORE_MATCH_DOT;
+			}
+		}
+
+		match_bonus[i] = score;
+		last_ch = ch;
+	}
+}
+
+static inline bool match_with_case(char a, char b, bool insensitive) {
+	if(insensitive) {
+		return tolower(a) == tolower(b);
+	} else {
+		return a == b;
+	}
+}
+
+static inline void match_row(int row, score_t* curr_D, score_t* curr_M,
+							 const score_t* last_D, const score_t * last_M,
+							 const char* needle, const char* haystack, int n, int m, score_t* match_bonus) {
+	int i = row;
+
+	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 (match_with_case(needle[i], haystack[j], true)) {
+			score_t score = SCORE_MIN;
+			if (!i) {
+				// first line we fill in a row for non-matching
+				score = (j * SCORE_GAP_LEADING) + match_bonus[j];
+			} else if (j) { /* i > 0 && j > 0*/
+				// we definitely match case insensitively already so if
+				//  our character isn't the same then we have a
+				//  different case
+				score_t consecutive_bonus = needle[i] == haystack[j] ? SCORE_MATCH_CONSECUTIVE : SCORE_MATCH_NOT_MATCH_CASE;
+
+				score = max(last_M[j - 1] + match_bonus[j],
+							/* consecutive match, doesn't stack
+							   with match_bonus */
+							last_D[j - 1] + consecutive_bonus);
+			}
+			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;
+		}
+	}
+}
+
+// Fuzzy matching scoring. Adapted from
+// https://github.com/jhawthorn/fzy/blob/master/src/match.c and
+// https://github.com/jhawthorn/fzy/blob/master/ALGORITHM.md
+// For a fuzzy match string needle being searched for in haystack we provide a
+// number score for how well we match.
+// We create two matrices of size needle_len (n) by haystack_len (m).
+// The first matrix is the score matrix. Each position (i,j) within this matrix
+// consists of the score that corresponds to the score that would be generated
+// by matching the first i characters of the needle with the first j
+// characters of the haystack. Gaps have a fixed penalty for having a gap along
+// with a linear penalty for gap size (c.f. gotoh's algorithm).
+// matches give a positive score, with a slight weight given to matches after
+// certain special characters (i.e. the first character after a `/` will be
+// "almost" consecutive but lower than an actual consecutive match).
+// Our second matrix is our diagonal matrix where we store the best match
+// that ends at a match. This allows us to calculate our gap penalties alongside
+// our consecutive match scores.
+// In addition, since we only rely on the current, and previous row of the
+// matrices and we only want to compute the score, we only store those scores
+// and reuse the previous rows (rather than storing the entire (n*m) matrix).
+// In addition we've simplified some of the algorithm compared to fzy to
+// improve legibility. (Can reimplement lookup tables later if wanted.)
+// Also, the reference algorithm does not take into account case sensitivity
+// which has been implemented here.
+
+
+score_t utils_fuzzy_score(const char* haystack, const char* needle) {
+	if(!*needle)
+		return SCORE_MIN;
+
+	int n = strlen(needle);
+	int m = strlen(haystack);
+	score_t match_bonus[m];
+	precompute_bonus(haystack, match_bonus);
+
+	if(m > MATCH_FUZZY_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_FUZZY_MAX_LEN], M[2][MATCH_FUZZY_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(i, curr_D, curr_M, last_D, last_M, needle, haystack, n, m, match_bonus);
+
+		SWAP(curr_D, last_D, score_t *);
+		SWAP(curr_M, last_M, score_t *);
+	}
+
+	return last_M[m - 1];
+}
+
 void utils_mkdir(char* path, mode_t mode) {
 	if(access(path, F_OK) != 0) {
 		char* tmp = strdup(path);

src/wofi.c

@@ -1112,42 +1112,32 @@ static gboolean do_multi_filter(GtkFlowBoxChild* row, gpointer data) {
 }
 
 static gint fuzzy_sort(const gchar *text1, const gchar *text2) {
-	char* _filter = strdup(filter);
-	size_t len = strlen(_filter);
-
-	char* t1 = strdup(text1);
-	size_t t1l = strlen(t1);
-
-	char* t2 = strdup(text2);
-	size_t t2l = strlen(t2);
-
-	if(insensitive) {
-		for(size_t count = 0; count < len; ++count) {
-			char chr = _filter[count];
-			if(isalpha(chr)) {
-				_filter[count] = tolower(chr);
+	gboolean match1 = do_fuzzy_strcomp(filter, text1);
+	gboolean match2 = do_fuzzy_strcomp(filter, text2);
+	// both filters match do fuzzy scoring
+	if(match1 && match2) {
+		score_t dist1 = utils_fuzzy_score(text1, filter);
+		score_t dist2 = utils_fuzzy_score(text2, filter);
+		if (dist1 == dist2) {
+			// same same
+			return 0;
+		} else if (dist1 > dist2) { // highest score wins.
+			// text1 goes first
+			return -1;
+		} else {
+			// text2 goes first
+			return 1;
 		}
+	} else if(match1) {
+		// text1 goes first
+		return -1;
+	} else if(match2) {
+		// text2 goes first
+		return 1;
+	} else {
+		// same same.
+		return 0;
 	}
-		for(size_t count = 0; count < t1l; ++count) {
-			char chr = t1[count];
-			if(isalpha(chr)) {
-				t1[count] = tolower(chr);
-			}
-		}
-		for(size_t count = 0; count < t2l; ++count) {
-			char chr = t2[count];
-			if(isalpha(chr)) {
-				t2[count] = tolower(chr);
-			}
-		}
-	}
-
-	size_t dist1 = utils_distance(t1, _filter);
-	size_t dist2 = utils_distance(t2, _filter);
-	free(_filter);
-	free(t1);
-	free(t2);
-	return dist1 - dist2;
 }
 
 // we sort based on how early in the string all the matches are.