1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/browser/devtools/shared/undo.js Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,206 @@
1.4 +/* -*- Mode: Javascript; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ft=javascript ts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +/**
1.11 + * A simple undo stack manager.
1.12 + *
1.13 + * Actions are added along with the necessary code to
1.14 + * reverse the action.
1.15 + *
1.16 + * @param function aChange Called whenever the size or position
1.17 + * of the undo stack changes, to use for updating undo-related
1.18 + * UI.
1.19 + * @param integer aMaxUndo Maximum number of undo steps.
1.20 + * defaults to 50.
1.21 + */
1.22 +function UndoStack(aMaxUndo)
1.23 +{
1.24 + this.maxUndo = aMaxUndo || 50;
1.25 + this._stack = [];
1.26 +}
1.27 +
1.28 +exports.UndoStack = UndoStack;
1.29 +
1.30 +UndoStack.prototype = {
1.31 + // Current index into the undo stack. Is positioned after the last
1.32 + // currently-applied change.
1.33 + _index: 0,
1.34 +
1.35 + // The current batch depth (see startBatch() for details)
1.36 + _batchDepth: 0,
1.37 +
1.38 + destroy: function Undo_destroy()
1.39 + {
1.40 + this.uninstallController();
1.41 + delete this._stack;
1.42 + },
1.43 +
1.44 + /**
1.45 + * Start a collection of related changes. Changes will be batched
1.46 + * together into one undo/redo item until endBatch() is called.
1.47 + *
1.48 + * Batches can be nested, in which case the outer batch will contain
1.49 + * all items from the inner batches. This allows larger user
1.50 + * actions made up of a collection of smaller actions to be
1.51 + * undone as a single action.
1.52 + */
1.53 + startBatch: function Undo_startBatch()
1.54 + {
1.55 + if (this._batchDepth++ === 0) {
1.56 + this._batch = [];
1.57 + }
1.58 + },
1.59 +
1.60 + /**
1.61 + * End a batch of related changes, performing its action and adding
1.62 + * it to the undo stack.
1.63 + */
1.64 + endBatch: function Undo_endBatch()
1.65 + {
1.66 + if (--this._batchDepth > 0) {
1.67 + return;
1.68 + }
1.69 +
1.70 + // Cut off the end of the undo stack at the current index,
1.71 + // and the beginning to prevent a stack larger than maxUndo.
1.72 + let start = Math.max((this._index + 1) - this.maxUndo, 0);
1.73 + this._stack = this._stack.slice(start, this._index);
1.74 +
1.75 + let batch = this._batch;
1.76 + delete this._batch;
1.77 + let entry = {
1.78 + do: function() {
1.79 + for (let item of batch) {
1.80 + item.do();
1.81 + }
1.82 + },
1.83 + undo: function() {
1.84 + for (let i = batch.length - 1; i >= 0; i--) {
1.85 + batch[i].undo();
1.86 + }
1.87 + }
1.88 + };
1.89 + this._stack.push(entry);
1.90 + this._index = this._stack.length;
1.91 + entry.do();
1.92 + this._change();
1.93 + },
1.94 +
1.95 + /**
1.96 + * Perform an action, adding it to the undo stack.
1.97 + *
1.98 + * @param function aDo Called to perform the action.
1.99 + * @param function aUndo Called to reverse the action.
1.100 + */
1.101 + do: function Undo_do(aDo, aUndo) {
1.102 + this.startBatch();
1.103 + this._batch.push({ do: aDo, undo: aUndo });
1.104 + this.endBatch();
1.105 + },
1.106 +
1.107 + /*
1.108 + * Returns true if undo() will do anything.
1.109 + */
1.110 + canUndo: function Undo_canUndo()
1.111 + {
1.112 + return this._index > 0;
1.113 + },
1.114 +
1.115 + /**
1.116 + * Undo the top of the undo stack.
1.117 + *
1.118 + * @return true if an action was undone.
1.119 + */
1.120 + undo: function Undo_canUndo()
1.121 + {
1.122 + if (!this.canUndo()) {
1.123 + return false;
1.124 + }
1.125 + this._stack[--this._index].undo();
1.126 + this._change();
1.127 + return true;
1.128 + },
1.129 +
1.130 + /**
1.131 + * Returns true if redo() will do anything.
1.132 + */
1.133 + canRedo: function Undo_canRedo()
1.134 + {
1.135 + return this._stack.length > this._index;
1.136 + },
1.137 +
1.138 + /**
1.139 + * Redo the most recently undone action.
1.140 + *
1.141 + * @return true if an action was redone.
1.142 + */
1.143 + redo: function Undo_canRedo()
1.144 + {
1.145 + if (!this.canRedo()) {
1.146 + return false;
1.147 + }
1.148 + this._stack[this._index++].do();
1.149 + this._change();
1.150 + return true;
1.151 + },
1.152 +
1.153 + _change: function Undo__change()
1.154 + {
1.155 + if (this._controllerWindow) {
1.156 + this._controllerWindow.goUpdateCommand("cmd_undo");
1.157 + this._controllerWindow.goUpdateCommand("cmd_redo");
1.158 + }
1.159 + },
1.160 +
1.161 + /**
1.162 + * ViewController implementation for undo/redo.
1.163 + */
1.164 +
1.165 + /**
1.166 + * Install this object as a command controller.
1.167 + */
1.168 + installController: function Undo_installController(aControllerWindow)
1.169 + {
1.170 + this._controllerWindow = aControllerWindow;
1.171 + aControllerWindow.controllers.appendController(this);
1.172 + },
1.173 +
1.174 + /**
1.175 + * Uninstall this object from the command controller.
1.176 + */
1.177 + uninstallController: function Undo_uninstallController()
1.178 + {
1.179 + if (!this._controllerWindow) {
1.180 + return;
1.181 + }
1.182 + this._controllerWindow.controllers.removeController(this);
1.183 + },
1.184 +
1.185 + supportsCommand: function Undo_supportsCommand(aCommand)
1.186 + {
1.187 + return (aCommand == "cmd_undo" ||
1.188 + aCommand == "cmd_redo");
1.189 + },
1.190 +
1.191 + isCommandEnabled: function Undo_isCommandEnabled(aCommand)
1.192 + {
1.193 + switch(aCommand) {
1.194 + case "cmd_undo": return this.canUndo();
1.195 + case "cmd_redo": return this.canRedo();
1.196 + };
1.197 + return false;
1.198 + },
1.199 +
1.200 + doCommand: function Undo_doCommand(aCommand)
1.201 + {
1.202 + switch(aCommand) {
1.203 + case "cmd_undo": return this.undo();
1.204 + case "cmd_redo": return this.redo();
1.205 + }
1.206 + },
1.207 +
1.208 + onEvent: function Undo_onEvent(aEvent) {},
1.209 +}
