[gnome-shell] Add a history manager

[Jasper St. Pierre <jstpierre src gnome org>]

commit cf3c631cded5a11718206946e44843bc0fa07951
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Sun Feb 13 11:40:20 2011 -0500

    Add a history manager
    
    runDialog and lookingGlass both implement a home-made history
    manager, each working slightly differently than each other in
    behavior and implementation.
    
    Extract the behavior and implementation from runDialog, which
    reads and saves to GSettings.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=642237

 js/Makefile.am     |    1 +
 js/misc/history.js |   72 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+), 0 deletions(-)
---
diff --git a/js/Makefile.am b/js/Makefile.am
index 7531c4d..e4a4145 100644
--- a/js/Makefile.am
+++ b/js/Makefile.am
@@ -7,6 +7,7 @@ nobase_dist_js_DATA = 	\
 	misc/fileUtils.js	\
 	misc/format.js		\
 	misc/gnomeSession.js	\
+	misc/history.js		\
 	misc/params.js		\
 	misc/util.js		\
 	perf/core.js		\
diff --git a/js/misc/history.js b/js/misc/history.js
new file mode 100644
index 0000000..69f27f9
--- /dev/null
+++ b/js/misc/history.js
@@ -0,0 +1,72 @@
+/* -*- mode: js2; js2-basic-offset: 4; indent-tabs-mode: nil -*- */
+
+const Lang = imports.lang;
+const Signals = imports.signals;
+
+const DEFAULT_LIMIT = 512;
+
+function HistoryManager(settings_key) {
+    this._init(settings_key);
+}
+
+HistoryManager.prototype = {
+    _init: function(settings_key, limit) {
+        this._limit = limit || DEFAULT_LIMIT;
+        this._key = settings_key;
+        this._history = global.settings.get_strv(settings_key);
+        this._historyIndex = -1;
+
+        global.settings.connect('changed::' + settings_key,
+                                Lang.bind(this, this._historyChanged));
+    },
+
+    _historyChanged: function() {
+        this._history = global.settings.get_strv(this._key);
+        this._historyIndex = this._history.length;
+    },
+
+    prevItem: function(text) {
+        this._setHistory(this._historyIndex--, text);
+        return this._indexChanged();
+    },
+
+    nextItem: function(text) {
+        this._setHistory(this._historyIndex++, text);
+        return this._indexChanged();
+    },
+
+    lastItem: function() {
+        this._historyIndex = this._history.length;
+        return this._indexChanged();
+    },
+
+    addItem: function(input) {
+        if (this._history.length == 0 ||
+            this._history[this._history.length - 1] != input) {
+
+            this._history.push(input);
+            this._save();
+        }   
+    },
+
+    _indexChanged: function() {
+        let current = this._history[this._historyIndex] || '';
+        this.emit('changed', current);
+        return current;
+    },
+
+    _setHistory: function(index, text) {
+        this._historyIndex = Math.max(this._historyIndex, 0);
+        this._historyIndex = Math.min(this._historyIndex, this._history.length);
+
+        if (text)
+            this._history[index] = text;
+    },
+
+    _save: function() {
+        if (this._history.length > this._limit)
+            this._history.splice(0, this._history.length - this._key);
+        global.settings.set_strv(this._key, this._history);
+    }
+};
+Signals.addSignalMethods(HistoryManager.prototype);