DevTools: "Jump between editing locations" experiment

Source/devtools/front_end/JumpHistoryManager.js

+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * @interface
+ */
+WebInspector.JumpHistoryEntry = function()
+{
+}
+
+WebInspector.JumpHistoryEntry.prototype = {
+    /**
+     * @return {boolean}
+     */
+    valid: function() { },
+
+    /**
+     * @param {WebInspector.JumpHistoryEntry} entry
+     */
+    merge: function(entry) { },
+
+    /**
+     * @return {boolean}
+     */
+    reveal: function() { },
+
+    /**
+     * @param {WebInspector.JumpHistoryEntry} entry
+     */
+    equal: function(entry) { }
+}
+
+WebInspector.JumpHistoryDepth = 20;
+
+/**
+ * @constructor
+ */
+WebInspector.JumpHistoryManager = function()
+{
+    this._history = [];
+    this._index = -1;
+}
+
+WebInspector.JumpHistoryManager.ShortcutKeys = {
+    JumpToPreviousLocation: WebInspector.KeyboardShortcut.makeDescriptor(WebInspector.KeyboardShortcut.Keys.Minus, WebInspector.KeyboardShortcut.Modifiers.Alt),
+    JumpToNextLocation: WebInspector.KeyboardShortcut.makeDescriptor(WebInspector.KeyboardShortcut.Keys.Plus, WebInspector.KeyboardShortcut.Modifiers.Alt),
+}
+
+WebInspector.JumpHistoryManager.prototype = {
+    handleShortcut: function(event)
+    {
+        var shortcutKey = WebInspector.KeyboardShortcut.makeKeyFromEvent(event);
+        if (shortcutKey === WebInspector.JumpHistoryManager.ShortcutKeys.JumpToPreviousLocation.key)
+            return this.rollback();
+        else if (shortcutKey === WebInspector.JumpHistoryManager.ShortcutKeys.JumpToNextLocation.key)
+            return this.rollover();
+        return false;
+    },
+
+    /**
+     * @param {WebInspector.JumpHistoryEntry} from
+     * @param {WebInspector.JumpHistoryEntry} to
+     */
+    jumpToPosition: function(from, to)
+    {
+        if (!WebInspector.experimentsSettings.jumpToPreviousLocation.isEnabled())
+            return;
+        if (this._muteJumpToPositionEvent) {
+            if (from)
+                this._historyEntryToUpdate.merge(from);
+            return;
+        }
+        if (from && !this.empty())
+            this.current().merge(from);
+        if (to)
+            this._push(to);
+    },
+
+    /**
+     * @return {boolean}
+     */
+    empty: function()
+    {
+        return !this._history.length;
+    },
+
+    /**
+     * @return {WebInspector.JumpHistoryEntry}
+     */
+    current: function()
+    {
+        if (this.empty())
+            return null;
+        return this._history[this._index];
+    },
+
+    /**
+     * @param {WebInspector.JumpHistoryEntry} entry
+     */
+    _push: function(entry)
+    {
+        if (!this.empty() && this.current().equal(entry))
+            return;
+        this._history.splice(++this._index, Infinity, entry);
+        if (this._history.length > WebInspector.JumpHistoryDepth) {
+            this._history.shift();
+            --this._index;
+        }
+    },
+
+    /**
+     * @param {function(WebInspector.JumpHistoryEntry):boolean} filterCallback
+     */
+    filterHistoryEntries: function(filterCallback)
+    {
+        for(var i = this._history.length - 1; i >= 0; --i) {
+            var entry = this._history[i];
+            if (filterCallback(entry)) {
+                this._history.remove(entry);
+                if (this._index >= i)
+                    --this._index;
+            }
+        }
+        if (this._index < 0 && this._history.length > 0)
+            this._index = 0;
+    },
+
+    /**
+     * @return {?WebInspector.JumpHistoryEntry}
+     */
+    _previousValidEntry: function()
+    {
+        if (this.empty())
+            return null;
+        for (var validEntryIndex = this._index - 1; validEntryIndex >= 0; --validEntryIndex) {
+            if (this._history[validEntryIndex].valid())
+                break;
+        }
+        if (validEntryIndex < 0) {
+            this._history.splice(0, this._index);
+            this._index = 0;
+            return null;
+        }
+        this._history.splice(validEntryIndex + 1, this._index - validEntryIndex - 1);
+        this._index = validEntryIndex;
+        return this._history[this._index];
+    },
+
+    /**
+     * @return {?WebInspector.JumpHistoryEntry}
+     */
+    _nextValidEntry: function()
+    {
+        if (this.empty())
+            return null;
+        for (var validEntryIndex = this._index + 1; validEntryIndex < this._history.length; ++validEntryIndex) {
+            if (this._history[validEntryIndex].valid())
+                break;
+        }
+        if (validEntryIndex >= this._history.length) {
+            this._history.splice(this._index + 1);
+            return null;
+        }
+        this._history.splice(this._index + 1, validEntryIndex - this._index - 1);
+        ++this._index;
+        return this._history[this._index];
+    },
+
+    /**
+     * @param {WebInspector.JumpHistoryEntry} previousEntry
+     * @param {WebInspector.JumpHistoryEntry} newEntry
+     * @return {boolean}
+     */
+    _applyHistoryEntry: function(previousEntry, newEntry)
+    {
+        this._muteJumpToPositionEvent = true;
+        this._historyEntryToUpdate = previousEntry;
+        var didReveal = newEntry.reveal();
+        delete this._historyEntryToUpdate;
+        delete this._muteJumpToPositionEvent;
+        return didReveal;
+    },
+
+    /**
+     * @return {boolean}
+     */
+    rollback: function()
+    {
+        var previous = this.current();
+        do {
+            var entry = this._previousValidEntry();
+            if (!entry)
+                return false;
+        } while (!this._applyHistoryEntry(previous, entry));
+        return true;
+    },
+
+    /**
+     * @return {boolean}
+     */
+    rollover: function()
+    {
+        var previous = this.current();
+        do {
+            var entry = this._nextValidEntry();
+            if (!entry)
+                return false;
+        } while (!this._applyHistoryEntry(previous, entry));
+        return true;
+    }
+}
+
+/**
+ * @type {?WebInspector.JumpHistoryManager}
+ */
+WebInspector.jumpHistoryManager = null;