From 338b0637408f6f6e3c4d3082a6fadaa6929b496c Mon Sep 17 00:00:00 2001
From: wintermute <kjulius@gmx.de>
Date: Wed, 20 Nov 2024 02:47:40 +0100
Subject: [PATCH] Feat: fuzzy matching flag -z

Adds the option to use fuzzy matching when filtering menu items.
Port of
https://tools.suckless.org/dmenu/patches/fuzzymatch/dmenu-fuzzymatch-4.6.diff
---
 client/common/common.c |  9 +++++-
 client/common/common.h |  1 +
 lib/bemenu.h           |  8 +++++
 lib/filter.c           | 71 +++++++++++++++++++++++++++++++++++++++---
 lib/internal.h         |  5 +++
 lib/menu.c             |  5 +++
 man/bemenu.1.scd.in    |  3 ++
 7 files changed, 96 insertions(+), 6 deletions(-)

diff --git a/client/common/common.c b/client/common/common.c
index 198cd053..41d9a3dc 100644
--- a/client/common/common.c
+++ b/client/common/common.c
@@ -172,6 +172,7 @@ usage(FILE *out, const char *name)
           " -h, --help            display this help and exit.\n"
           " -v, --version         display version.\n"
           " -i, --ignorecase      match items case insensitively.\n"
+          " -z, --fuzzy           enable fuzzy matching.\n"
           " -F, --filter          filter entries for a given string before showing the menu.\n"
           " -w, --wrap            wraps cursor selection.\n"
           " -l, --list            list items vertically down or up with the given number of lines(number of lines down/up). (down (default), up)\n"
@@ -272,6 +273,7 @@ do_getopt(struct client *client, int *argc, char **argv[])
         { "version",      no_argument,       0, 'v' },
 
         { "ignorecase",   no_argument,       0, 'i' },
+        { "fuzzy",        no_argument,       0, 'z' },
         { "filter",       required_argument, 0, 'F' },
         { "wrap",         no_argument,       0, 'w' },
         { "list",         required_argument, 0, 'l' },
@@ -340,7 +342,7 @@ do_getopt(struct client *client, int *argc, char **argv[])
     for (optind = 0;;) {
         int32_t opt;
 
-        if ((opt = getopt_long(*argc, *argv, "hviwcl:I:p:P:I:x:bfF:m:H:M:W:B:R:nsCTK", opts, NULL)) < 0)
+        if ((opt = getopt_long(*argc, *argv, "hvizwcl:I:p:P:I:x:bfF:m:H:M:W:B:R:nsCTK", opts, NULL)) < 0)
             break;
         
         switch (opt) {
@@ -353,6 +355,9 @@ do_getopt(struct client *client, int *argc, char **argv[])
             case 'i':
                 client->filter_mode = BM_FILTER_MODE_DMENU_CASE_INSENSITIVE;
                 break;
+            case 'z':
+                client->fuzzy = true;
+                break;
             case 'F':
                 client->initial_filter = optarg;
                 break;
@@ -594,6 +599,8 @@ menu_with_options(struct client *client)
     bm_menu_set_border_size(menu, client->border_size);
     bm_menu_set_border_radius(menu, client->border_radius);
     bm_menu_set_key_binding(menu, client->key_binding);
+    bm_menu_set_fuzzy_mode(menu, client->fuzzy);
+
 
     if (client->center) {
         bm_menu_set_align(menu, BM_ALIGN_CENTER);
diff --git a/client/common/common.h b/client/common/common.h
index e5ed9ab2..1374f91b 100644
--- a/client/common/common.h
+++ b/client/common/common.h
@@ -46,6 +46,7 @@ struct client {
     enum bm_password_mode password;
     enum bm_key_binding key_binding;
     char *monitor_name;
+    bool fuzzy;
 };
 
 char* cstrcopy(const char *str, size_t size);
diff --git a/lib/bemenu.h b/lib/bemenu.h
index 740783a3..6b133da9 100644
--- a/lib/bemenu.h
+++ b/lib/bemenu.h
@@ -934,6 +934,14 @@ BM_PUBLIC enum bm_password_mode bm_menu_get_password(struct bm_menu *menu);
  */
 BM_PUBLIC void bm_menu_set_key_binding(struct bm_menu *menu, enum bm_key_binding);
 
+/**
+ * Specify whether fuzzy matching should be used.
+ *
+ * @param menu bm_menu instance to set the fuzzy mode on.
+ * @param fuzzy true to enable fuzzy matching.
+ */
+BM_PUBLIC void bm_menu_set_fuzzy_mode(struct bm_menu *menu, bool fuzzy);
+
 
 /**  @} Properties */
 
diff --git a/lib/filter.c b/lib/filter.c
index 2b4e4655..1d73b2ab 100644
--- a/lib/filter.c
+++ b/lib/filter.c
@@ -79,17 +79,32 @@ tokenize(struct bm_menu *menu, char ***out_tokv, uint32_t *out_tokc)
     return NULL;
 }
 
+struct fuzzy_match {
+    struct bm_item *item;
+    int distance;
+};
+
+static int fuzzy_match_comparator(const void *a, const void *b) {
+    const struct fuzzy_match *fa = (const struct fuzzy_match *)a;
+    const struct fuzzy_match *fb = (const struct fuzzy_match *)b;
+
+    return fa->distance - fb->distance;
+}
+
+
 /**
- * Dmenu filterer that accepts substring function.
+ * Dmenu filterer that accepts substring function or fuzzy match.
  *
  * @param menu bm_menu instance to filter.
  * @param addition This will be 1, if filter is same as previous filter with something appended.
  * @param fstrstr Substring function used to match items.
+ * @param fstrncmp String comparison function for exact matches.
  * @param out_nmemb uint32_t reference to filtered items count.
+ * @param fuzzy Boolean flag to toggle fuzzy matching.
  * @return Pointer to array of bm_item pointers.
  */
 static struct bm_item**
-filter_dmenu_fun(struct bm_menu *menu, char addition, char* (*fstrstr)(const char *a, const char *b), int (*fstrncmp)(const char *a, const char *b, size_t len), uint32_t *out_nmemb)
+filter_dmenu_fun(struct bm_menu *menu, char addition, char* (*fstrstr)(const char *a, const char *b), int (*fstrncmp)(const char *a, const char *b, size_t len), uint32_t *out_nmemb, bool fuzzy)
 {
     assert(menu && fstrstr && fstrncmp && out_nmemb);
     *out_nmemb = 0;
@@ -114,13 +129,48 @@ filter_dmenu_fun(struct bm_menu *menu, char addition, char* (*fstrstr)(const cha
         goto fail;
 
     const char *filter = menu->filter ? menu->filter : "";
+    if (strlen(filter) == 0) {
+        goto fail;
+    }
     size_t len = (tokc ? strlen(tokv[0]) : 0);
     uint32_t i, f, e;
-    for (e = f = i = 0; i < count; ++i) {
+    f = e = 0;
+
+    struct fuzzy_match *fuzzy_matches = NULL;
+
+    int fuzzy_match_count = 0;
+
+    if (fuzzy && !(fuzzy_matches = calloc(count, sizeof(*fuzzy_matches))))
+        goto fail;
+
+    for (i = 0; i < count; ++i) {
         struct bm_item *item = items[i];
         if (!item->text && tokc != 0)
             continue;
 
+        if (fuzzy && tokc && item->text) {
+            const char *text = item->text;
+            int sidx = -1, eidx = -1, pidx = 0, text_len = strlen(text), distance = 0;
+            for (int j = 0; j < text_len && text[j]; ++j) {
+                if (!fstrncmp(&text[j], &filter[pidx], 1)) {
+                    if (sidx == -1)
+                        sidx = j;
+                    pidx++;
+                    if (pidx == strlen(filter)) {
+                        eidx = j;
+                        break;
+                    }
+                }
+            }
+            if (eidx != -1) {
+                distance = eidx - sidx + (text_len - eidx + sidx) / 3;
+                fuzzy_matches[fuzzy_match_count++] = (struct fuzzy_match){ item, distance };
+                continue;
+            }
+        }
+
+        if (fuzzy) continue;
+
         if (tokc && item->text) {
             uint32_t t;
             for (t = 0; t < tokc && fstrstr(item->text, tokv[t]); ++t);
@@ -142,12 +192,23 @@ filter_dmenu_fun(struct bm_menu *menu, char addition, char* (*fstrstr)(const cha
         f++; /* where do all matches end */
     }
 
+    if (fuzzy && fuzzy_match_count > 0) {
+        qsort(fuzzy_matches, fuzzy_match_count, sizeof(struct fuzzy_match), fuzzy_match_comparator);
+
+        for (int j = 0; j < fuzzy_match_count; ++j) {
+            filtered[f++] = fuzzy_matches[j].item;
+        }
+
+        free(fuzzy_matches);
+    }
+
     free(buffer);
     free(tokv);
     return shrink_list(&filtered, menu->items.count, (*out_nmemb = f));
 
 fail:
     free(filtered);
+    free(fuzzy_matches);
     free(buffer);
     return NULL;
 }
@@ -163,7 +224,7 @@ filter_dmenu_fun(struct bm_menu *menu, char addition, char* (*fstrstr)(const cha
 struct bm_item**
 bm_filter_dmenu(struct bm_menu *menu, bool addition, uint32_t *out_nmemb)
 {
-    return filter_dmenu_fun(menu, addition, strstr, strncmp, out_nmemb);
+    return filter_dmenu_fun(menu, addition, strstr, strncmp, out_nmemb, menu->fuzzy);
 }
 
 /**
@@ -177,7 +238,7 @@ bm_filter_dmenu(struct bm_menu *menu, bool addition, uint32_t *out_nmemb)
 struct bm_item**
 bm_filter_dmenu_case_insensitive(struct bm_menu *menu, bool addition, uint32_t *out_nmemb)
 {
-    return filter_dmenu_fun(menu, addition, bm_strupstr, bm_strnupcmp, out_nmemb);
+    return filter_dmenu_fun(menu, addition, bm_strupstr, bm_strnupcmp, out_nmemb, menu->fuzzy);
 }
 
 /* vim: set ts=8 sw=4 tw=0 :*/
diff --git a/lib/internal.h b/lib/internal.h
index 056f16a6..81da2c08 100644
--- a/lib/internal.h
+++ b/lib/internal.h
@@ -457,6 +457,11 @@ struct bm_menu {
      */
     char vim_mode;
     uint32_t vim_last_key;
+
+    /**
+     * Should fuzzy matching be used?
+     */
+    bool fuzzy;
 };
 
 /* library.c */
diff --git a/lib/menu.c b/lib/menu.c
index 741d7828..9a14adbe 100644
--- a/lib/menu.c
+++ b/lib/menu.c
@@ -779,6 +779,11 @@ bm_menu_set_key_binding(struct bm_menu *menu, enum bm_key_binding key_binding){
     menu->key_binding = key_binding;
 }
 
+void
+bm_menu_set_fuzzy_mode(struct bm_menu *menu, bool fuzzy){
+    menu->fuzzy = fuzzy;
+}
+
 struct bm_item**
 bm_menu_get_selected_items(const struct bm_menu *menu, uint32_t *out_nmemb)
 {
diff --git a/man/bemenu.1.scd.in b/man/bemenu.1.scd.in
index ea695aad..7a75152a 100644
--- a/man/bemenu.1.scd.in
+++ b/man/bemenu.1.scd.in
@@ -45,6 +45,9 @@ list of executables under PATH and the selected items are executed.
 *-i, --ignorecase*
 	Filter items case-insensitively.
 
+*-z, --fuzzy*
+	Filter items fuzzily.
+
 *-K, --no-keyboard*
 	Disable all keyboard events.