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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
commit26a029d407be480d791972afb5975cf62c9360a6 (patch)
treef435a8308119effd964b339f76abb83a57c29483 /devtools/client/shared/undo.js
parentInitial commit. (diff)
downloadfirefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz
firefox-26a029d407be480d791972afb5975cf62c9360a6.zip
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'devtools/client/shared/undo.js')
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diff --git a/devtools/client/shared/undo.js b/devtools/client/shared/undo.js
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+/**
+ * A simple undo stack manager.
+ *
+ * Actions are added along with the necessary code to
+ * reverse the action.
+ *
+ * @param integer maxUndo Maximum number of undo steps.
+ * defaults to 50.
+ */
+function UndoStack(maxUndo) {
+ this.maxUndo = maxUndo || 50;
+ this._stack = [];
+}
+
+exports.UndoStack = UndoStack;
+
+UndoStack.prototype = {
+ // Current index into the undo stack. Is positioned after the last
+ // currently-applied change.
+ _index: 0,
+
+ // The current batch depth (see startBatch() for details)
+ _batchDepth: 0,
+
+ destroy() {
+ this.uninstallController();
+ delete this._stack;
+ },
+
+ /**
+ * Start a collection of related changes. Changes will be batched
+ * together into one undo/redo item until endBatch() is called.
+ *
+ * Batches can be nested, in which case the outer batch will contain
+ * all items from the inner batches. This allows larger user
+ * actions made up of a collection of smaller actions to be
+ * undone as a single action.
+ */
+ startBatch() {
+ if (this._batchDepth++ === 0) {
+ this._batch = [];
+ }
+ },
+
+ /**
+ * End a batch of related changes, performing its action and adding
+ * it to the undo stack.
+ */
+ endBatch() {
+ if (--this._batchDepth > 0) {
+ return;
+ }
+
+ // Cut off the end of the undo stack at the current index,
+ // and the beginning to prevent a stack larger than maxUndo.
+ const start = Math.max(this._index + 1 - this.maxUndo, 0);
+ this._stack = this._stack.slice(start, this._index);
+
+ const batch = this._batch;
+ delete this._batch;
+ const entry = {
+ do() {
+ for (const item of batch) {
+ item.do();
+ }
+ },
+ undo() {
+ for (let i = batch.length - 1; i >= 0; i--) {
+ batch[i].undo();
+ }
+ },
+ };
+ this._stack.push(entry);
+ this._index = this._stack.length;
+ entry.do();
+ },
+
+ /**
+ * Perform an action, adding it to the undo stack.
+ *
+ * @param function toDo Called to perform the action.
+ * @param function undo Called to reverse the action.
+ */
+ do(toDo, undo) {
+ this.startBatch();
+ this._batch.push({ do: toDo, undo });
+ this.endBatch();
+ },
+
+ /*
+ * Returns true if undo() will do anything.
+ */
+ canUndo() {
+ return this._index > 0;
+ },
+
+ /**
+ * Undo the top of the undo stack.
+ *
+ * @return true if an action was undone.
+ */
+ undo() {
+ if (!this.canUndo()) {
+ return false;
+ }
+ this._stack[--this._index].undo();
+ return true;
+ },
+
+ /**
+ * Returns true if redo() will do anything.
+ */
+ canRedo() {
+ return this._stack.length > this._index;
+ },
+
+ /**
+ * Redo the most recently undone action.
+ *
+ * @return true if an action was redone.
+ */
+ redo() {
+ if (!this.canRedo()) {
+ return false;
+ }
+ this._stack[this._index++].do();
+ return true;
+ },
+
+ /**
+ * ViewController implementation for undo/redo.
+ */
+
+ /**
+ * Install this object as a command controller.
+ */
+ installController(controllerWindow) {
+ const controllers = controllerWindow.controllers;
+ // Only available when running in a Firefox panel.
+ if (!controllers || !controllers.appendController) {
+ return;
+ }
+
+ this._controllerWindow = controllerWindow;
+ controllers.appendController(this);
+ },
+
+ /**
+ * Uninstall this object from the command controller.
+ */
+ uninstallController() {
+ if (!this._controllerWindow) {
+ return;
+ }
+ this._controllerWindow.controllers.removeController(this);
+ },
+
+ supportsCommand(command) {
+ return command == "cmd_undo" || command == "cmd_redo";
+ },
+
+ isCommandEnabled(command) {
+ switch (command) {
+ case "cmd_undo":
+ return this.canUndo();
+ case "cmd_redo":
+ return this.canRedo();
+ }
+ return false;
+ },
+
+ doCommand(command) {
+ switch (command) {
+ case "cmd_undo":
+ return this.undo();
+ case "cmd_redo":
+ return this.redo();
+ default:
+ return null;
+ }
+ },
+
+ onEvent(event) {},
+};