1 files changed, 71 insertions, 0 deletions
diff --git a/devtools/shared/gcli/source/lib/gcli/ui/history.js b/devtools/shared/gcli/source/lib/gcli/ui/history.js
new file mode 100644
index 000000000..a9d4b868c
--- /dev/null
+++ b/devtools/shared/gcli/source/lib/gcli/ui/history.js
@@ -0,0 +1,71 @@
+/*
+ * Copyright 2012, Mozilla Foundation and contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+'use strict';
+
+/**
+ * A History object remembers commands that have been entered in the past and
+ * provides an API for accessing them again.
+ * See Bug 681340: Search through history (like C-r in bash)?
+ */
+function History() {
+  // This is the actual buffer where previous commands are kept.
+  // 'this._buffer[0]' should always be equal the empty string. This is so
+  // that when you try to go in to the "future", you will just get an empty
+  // command.
+  this._buffer = [''];
+
+  // This is an index in to the history buffer which points to where we
+  // currently are in the history.
+  this._current = 0;
+}
+
+/**
+ * Avoid memory leaks
+ */
+History.prototype.destroy = function() {
+  this._buffer = undefined;
+};
+
+/**
+ * Record and save a new command in the history.
+ */
+History.prototype.add = function(command) {
+  this._buffer.splice(1, 0, command);
+  this._current = 0;
+};
+
+/**
+ * Get the next (newer) command from history.
+ */
+History.prototype.forward = function() {
+  if (this._current > 0 ) {
+    this._current--;
+  }
+  return this._buffer[this._current];
+};
+
+/**
+ * Get the previous (older) item from history.
+ */
+History.prototype.backward = function() {
+  if (this._current < this._buffer.length - 1) {
+    this._current++;
+  }
+  return this._buffer[this._current];
+};
+
+exports.History = History;