search: Split out the description highlighter into its own class

No functional change yet, only preparation to allow adding a unit test
later on.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2033>

js/misc/util.js

@@ -2,7 +2,7 @@
 /* exported findUrls, spawn, spawnCommandLine, spawnApp, trySpawnCommandLine,
             formatTime, formatTimeSpan, createTimeLabel, insertSorted,
             ensureActorVisibleInScrollView, wiggle, lerp, GNOMEversionCompare,
-            DBusSenderChecker */
+            DBusSenderChecker, Highlighter */
 
 const { Clutter, Gio, GLib, Shell, St, GnomeDesktop } = imports.gi;
 const Gettext = imports.gettext;
@@ -555,3 +555,38 @@ var DBusSenderChecker = class {
         this._watchList = [];
     }
 };
+
+/* @class Highlighter Highlight given terms in text using markup. */
+var Highlighter = class {
+    /**
+     * @param {?string[]} terms - list of terms to highlight
+     */
+    constructor(terms) {
+        if (!terms)
+            return;
+
+        const escapedTerms = terms
+            .map(term => Shell.util_regex_escape(term))
+            .filter(term => term.length > 0);
+
+        if (escapedTerms.length === 0)
+            return;
+
+        this._highlightRegex = new RegExp('(%s)'.format(
+            escapedTerms.join('|')), 'gi');
+    }
+
+    /**
+     * Highlight all occurences of the terms defined for this
+     * highlighter in the provided text using markup.
+     *
+     * @param {string} text - text to highlight the defined terms in
+     * @returns {string}
+     */
+    highlight(text) {
+        if (!this._highlightRegex)
+            return text;
+
+        return text.replace(this._highlightRegex, '<b>$1</b>');
+    }
+};

js/ui/search.js

@@ -10,6 +10,8 @@ const ParentalControlsManager = imports.misc.parentalControlsManager;
 const RemoteSearch = imports.ui.remoteSearch;
 const Util = imports.misc.util;
 
+const { Highlighter } = imports.misc.util;
+
 const SEARCH_PROVIDERS_SCHEMA = 'org.gnome.desktop.search-providers';
 
 var MAX_LIST_SEARCH_RESULTS_ROWS = 5;
@@ -596,7 +598,7 @@ var SearchResultsView = GObject.registerClass({
 
         this._providers = [];
 
-        this._highlightRegex = null;
+        this._highlighter = new Highlighter();
 
         this._searchSettings = new Gio.Settings({ schema_id: SEARCH_PROVIDERS_SCHEMA });
         this._searchSettings.connect('changed::disabled', this._reloadRemoteProviders.bind(this));
@@ -739,8 +741,7 @@ var SearchResultsView = GObject.registerClass({
         if (this._searchTimeoutId == 0)
             this._searchTimeoutId = GLib.timeout_add(GLib.PRIORITY_DEFAULT, 150, this._onSearchTimeout.bind(this));
 
-        let escapedTerms = this._terms.map(term => Shell.util_regex_escape(term));
+        this._highlighter = new Highlighter(this._terms);
-        this._highlightRegex = new RegExp('(%s)'.format(escapedTerms.join('|')), 'gi');
 
         this.emit('terms-changed');
     }
@@ -894,10 +895,7 @@ var SearchResultsView = GObject.registerClass({
         if (!description)
             return '';
 
-        if (!this._highlightRegex)
+        return this._highlighter.highlight(description);
-            return description;
-
-        return description.replace(this._highlightRegex, '<b>$1</b>');
     }
 });