From 94353eb52055927d9079f3d9e33da1c954abf386 Mon Sep 17 00:00:00 2001
From: aleks <aleks.stier@icloud.com>
Date: Wed, 26 Jun 2019 13:25:10 +0200
Subject: [PATCH] Add support for fuzzy-matching

---
 config.def.h |  1 +
 config.mk    |  2 +-
 dmenu.c      | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 91 insertions(+), 1 deletion(-)

diff --git a/config.def.h b/config.def.h
index 1edb647..51612b9 100644
--- a/config.def.h
+++ b/config.def.h
@@ -2,6 +2,7 @@
 /* Default settings; can be overriden by command line. */
 
 static int topbar = 1;                      /* -b  option; if 0, dmenu appears at bottom     */
+static int fuzzy = 1;                      /* -F  option; if 0, dmenu doesn't use fuzzy matching     */
 /* -fn option overrides fonts[0]; default X11 font or font set */
 static const char *fonts[] = {
 	"monospace:size=10"
diff --git a/config.mk b/config.mk
index 0929b4a..d14309a 100644
--- a/config.mk
+++ b/config.mk
@@ -20,7 +20,7 @@ FREETYPEINC = /usr/include/freetype2
 
 # includes and libs
 INCS = -I$(X11INC) -I$(FREETYPEINC)
-LIBS = -L$(X11LIB) -lX11 $(XINERAMALIBS) $(FREETYPELIBS)
+LIBS = -L$(X11LIB) -lX11 $(XINERAMALIBS) $(FREETYPELIBS) -lm
 
 # flags
 CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700 -D_POSIX_C_SOURCE=200809L -DVERSION=\"$(VERSION)\" $(XINERAMAFLAGS)
diff --git a/dmenu.c b/dmenu.c
index 6b8f51b..96ddc98 100644
--- a/dmenu.c
+++ b/dmenu.c
@@ -1,6 +1,7 @@
 /* See LICENSE file for copyright and license details. */
 #include <ctype.h>
 #include <locale.h>
+#include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -32,6 +33,7 @@ struct item {
 	char *text;
 	struct item *left, *right;
 	int out;
+	double distance;
 };
 
 static char text[BUFSIZ] = "";
@@ -210,9 +212,94 @@ grabkeyboard(void)
 	die("cannot grab keyboard");
 }
 
+int
+compare_distance(const void *a, const void *b)
+{
+	struct item *da = *(struct item **) a;
+	struct item *db = *(struct item **) b;
+
+	if (!db)
+		return 1;
+	if (!da)
+		return -1;
+
+	return da->distance == db->distance ? 0 : da->distance < db->distance ? -1 : 1;
+}
+
+void
+fuzzymatch(void)
+{
+	/* bang - we have so much memory */
+	struct item *it;
+	struct item **fuzzymatches = NULL;
+	char c;
+	int number_of_matches = 0, i, pidx, sidx, eidx;
+	int text_len = strlen(text), itext_len;
+
+	matches = matchend = NULL;
+
+	/* walk through all items */
+	for (it = items; it && it->text; it++) {
+		if (text_len) {
+			itext_len = strlen(it->text);
+			pidx = 0; /* pointer */
+			sidx = eidx = -1; /* start of match, end of match */
+			/* walk through item text */
+			for (i = 0; i < itext_len && (c = it->text[i]); i++) {
+				/* fuzzy match pattern */
+				if (!fstrncmp(&text[pidx], &c, 1)) {
+					if(sidx == -1)
+						sidx = i;
+					pidx++;
+					if (pidx == text_len) {
+						eidx = i;
+						break;
+					}
+				}
+			}
+			/* build list of matches */
+			if (eidx != -1) {
+				/* compute distance */
+				/* add penalty if match starts late (log(sidx+2))
+				 * add penalty for long a match without many matching characters */
+				it->distance = log(sidx + 2) + (double)(eidx - sidx - text_len);
+				/* fprintf(stderr, "distance %s %f\n", it->text, it->distance); */
+				appenditem(it, &matches, &matchend);
+				number_of_matches++;
+			}
+		} else {
+			appenditem(it, &matches, &matchend);
+		}
+	}
+
+	if (number_of_matches) {
+		/* initialize array with matches */
+		if (!(fuzzymatches = realloc(fuzzymatches, number_of_matches * sizeof(struct item*))))
+			die("cannot realloc %u bytes:", number_of_matches * sizeof(struct item*));
+		for (i = 0, it = matches; it && i < number_of_matches; i++, it = it->right) {
+			fuzzymatches[i] = it;
+		}
+		/* sort matches according to distance */
+		qsort(fuzzymatches, number_of_matches, sizeof(struct item*), compare_distance);
+		/* rebuild list of matches */
+		matches = matchend = NULL;
+		for (i = 0, it = fuzzymatches[i];  i < number_of_matches && it && \
+				it->text; i++, it = fuzzymatches[i]) {
+			appenditem(it, &matches, &matchend);
+		}
+		free(fuzzymatches);
+	}
+	curr = sel = matches;
+	calcoffsets();
+}
+
 static void
 match(void)
 {
+	if (fuzzy) {
+		fuzzymatch();
+		return;
+	}
 	static char **tokv = NULL;
 	static int tokn = 0;
 
@@ -702,6 +789,8 @@ main(int argc, char *argv[])
 			topbar = 0;
 		else if (!strcmp(argv[i], "-f"))   /* grabs keyboard before reading stdin */
 			fast = 1;
+		else if (!strcmp(argv[i], "-F"))   /* grabs keyboard before reading stdin */
+			fuzzy = 0;
 		else if (!strcmp(argv[i], "-i")) { /* case-insensitive item matching */
 			fstrncmp = strncasecmp;
 			fstrstr = cistrstr;
-- 
2.22.0