feat(search): Sort search results by levenshtein distance

Author: mmstick

src/dialog_launcher.ts

@@ -11,6 +11,7 @@ import * as result from 'result';
 import * as search from 'dialog_search';
 import * as launch from 'launcher_service';
 import * as plugins from 'launcher_plugins';
+import * as levenshtein from 'levenshtein';
 
 import type { ShellWindow } from 'window';
 import type { Ext } from 'extension';
@@ -90,15 +91,13 @@ export class Launcher extends search.Search {
                 return needles.every((n) => hay.includes(n));
             };
 
-            let apps: Array<launch.SearchOption> = new Array();
-
             // Filter matching windows
             for (const window of ext.tab_list(Meta.TabList.NORMAL, null)) {
                 const retain = contains_pattern(window.name(ext), needles)
                     || contains_pattern(window.meta.get_title(), needles);
 
                 if (retain) {
-                    apps.push(window_selection(ext, window, this.icon_size()))
+                    this.options.push(window_selection(ext, window, this.icon_size()))
                 }
             }
 
@@ -113,7 +112,7 @@ export class Launcher extends search.Search {
                 if (retain) {
                     const generic = app.generic_name();
 
-                    apps.push(new launch.SearchOption(
+                    this.options.push(new launch.SearchOption(
                         app.name(),
                         generic ? generic + " — " + where : where,
                         'application-default-symbolic',
@@ -125,19 +124,26 @@ export class Launcher extends search.Search {
             }
 
             // Sort the list of matched selections
-            apps.sort((a, b) => {
-                const a_name = a.title.toLowerCase();
-                const b_name = b.title.toLowerCase();
+            this.options.sort((a, b) => {
+                const a_name = a.title.toLowerCase()
+                const b_name = b.title.toLowerCase()
 
                 const pattern_lower = pattern.toLowerCase()
 
-                const a_includes = a_name.includes(pattern_lower);
-                const b_includes = b_name.includes(pattern_lower);
+                let a_name_weight = levenshtein.compare(pattern_lower, a_name)
 
-                return ((a_includes && b_includes) || (!a_includes && !b_includes)) ? (a_name > b_name ? 1 : 0) : a_includes ? -1 : b_includes ? 1 : 0;
-            });
+                let b_name_weight = levenshtein.compare(pattern_lower, b_name)
+
+                if (a.description) {
+                    a_name_weight = Math.min(a_name_weight, levenshtein.compare(pattern_lower, a.description.toLowerCase()))
+                }
 
-            for (const app of apps) this.options.push(app)
+                if (b.description) {
+                    b_name_weight = Math.min(b_name_weight, levenshtein.compare(pattern_lower, b.description.toLowerCase()))
+                }
+
+                return a_name_weight > b_name_weight ? 1 : 0
+            });
 
             // Truncate excess items from the list
             this.options.splice(this.list_max());

src/levenshtein.ts

@@ -0,0 +1,100 @@
+/**
+ * Based on https://github.com/gustf/js-levenshtein/blob/master/index.js
+ * MIT License
+ * Copyright (c) 2017 Gustaf Andersson
+ */
+
+function _min(d0: number, d1: number, d2: number, bx: number, ay: number): number {
+    return d0 < d1 || d2 < d1
+        ? d0 > d2
+            ? d2 + 1
+            : d0 + 1
+        : bx === ay
+            ? d1
+            : d1 + 1
+}
+
+export function compare(a: string, b: string): number {
+    if (a === b) return 0
+
+    if (a.length > b.length) {
+        const tmp = a
+        a = b
+        b = tmp
+    }
+
+    let la = a.length
+    let lb = b.length
+
+    while (la > 0 && (a.charCodeAt(la - 1) === b.charCodeAt(lb - 1))) {
+        la--
+        lb--
+    }
+
+    let offset = 0
+
+    while (offset < la && (a.charCodeAt(offset) === b.charCodeAt(offset))) {
+        offset++
+    }
+
+    la -= offset
+    lb -= offset
+
+    if (la === 0 || lb < 3) return lb
+
+    let x = 0,
+        y = 0,
+        d0 = 0,
+        d1 = 0,
+        d2 = 0,
+        d3 = 0,
+        dd = 0,
+        dy = 0,
+        ay = 0,
+        bx0 = 0,
+        bx1 = 0,
+        bx2 = 0,
+        bx3 = 0
+
+    const vector = []
+
+    for (y = 0; y < la; y++) {
+      vector.push(y + 1)
+      vector.push(a.charCodeAt(offset + y))
+    }
+
+    let len = vector.length - 1
+
+    for (; x < lb - 3;) {
+        bx0 = b.charCodeAt(offset + (d0 = x))
+        bx1 = b.charCodeAt(offset + (d1 = x + 1))
+        bx2 = b.charCodeAt(offset + (d2 = x + 2))
+        bx3 = b.charCodeAt(offset + (d3 = x + 3))
+        dd = (x += 4)
+        for (y = 0; y < len; y += 2) {
+            dy = vector[y]
+            ay = vector[y + 1]
+            d0 = _min(dy, d0, d1, bx0, ay)
+            d1 = _min(d0, d1, d2, bx1, ay)
+            d2 = _min(d1, d2, d3, bx2, ay)
+            dd = _min(d2, d3, dd, bx3, ay)
+            vector[y] = dd
+            d3 = d2
+            d2 = d1
+            d1 = d0
+            d0 = dy
+        }
+    }
+
+    for (; x < lb;) {
+        bx0 = b.charCodeAt(offset + (d0 = x))
+        dd = ++x
+        for (y = 0; y < len; y += 2) {
+            dy = vector[y]
+            vector[y] = dd = _min(dy, d0, dd, bx0, vector[y + 1])
+            d0 = dy
+        }
+    }
+
+    return dd
+}