Source/WebInspectorUI/UserInterface/Views/ObjectTreeView.js - WebKit - Git at Google

 /*
  * Copyright (C) 2015 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. 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.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS 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 APPLE INC. OR ITS 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.
  */

 WI.ObjectTreeView = class ObjectTreeView extends WI.Object
 {
     constructor(object, mode, propertyPath, forceExpanding)
     {
         super();

         console.assert(object instanceof WI.RemoteObject);
         console.assert(!propertyPath || propertyPath instanceof WI.PropertyPath);

         var providedPropertyPath = propertyPath instanceof WI.PropertyPath;

         this._object = object;
         this._mode = mode || WI.ObjectTreeView.defaultModeForObject(object);
         this._propertyPath = propertyPath || new WI.PropertyPath(this._object, "this");
         this._expanded = false;
         this._hasLosslessPreview = false;
         this._includeProtoProperty = true;

         // If ObjectTree is used outside of the console, we do not know when to release
         // WeakMap entries. Currently collapse would work. For the console, we can just
         // listen for console clear events. Currently all ObjectTrees are in the console.
         this._inConsole = true;

         this._fetchStart = 0;
         this._fetchEnd = ObjectTreeView.showMoreFetchCount;
         this._fetchEndIndex = 0;

         // Always force expanding for classes.
         if (this._object.isClass())
             forceExpanding = true;

         this._element = document.createElement("div");
         this._element.__objectTree = this;
         this._element.className = "object-tree";

         if (this._object.preview) {
             this._previewView = new WI.ObjectPreviewView(this._object, this._object.preview);
             this._previewView.setOriginatingObjectInfo(this._object, providedPropertyPath ? propertyPath : null);
             this._previewView.element.addEventListener("click", this._handlePreviewOrTitleElementClick.bind(this));
             this._element.appendChild(this._previewView.element);

             if (this._previewView.lossless && !this._propertyPath.parent && !forceExpanding) {
                 this._hasLosslessPreview = true;
                 this.element.classList.add("lossless-preview");
             }
         } else {
             this._titleElement = document.createElement("span");
             this._titleElement.className = "title";
             this._titleElement.appendChild(WI.FormattedValue.createElementForRemoteObject(this._object));
             this._titleElement.addEventListener("click", this._handlePreviewOrTitleElementClick.bind(this));
             this._element.appendChild(this._titleElement);
         }

         this._outline = new WI.TreeOutline;
         this._outline.compact = true;
         this._outline.customIndent = true;
         this._outline.element.classList.add("object");
         this._element.appendChild(this._outline.element);

         // FIXME: Support editable ObjectTrees.
     }

     // Static

     static defaultModeForObject(object)
     {
         if (object.subtype === "class")
             return WI.ObjectTreeView.Mode.ClassAPI;

         return WI.ObjectTreeView.Mode.Properties;
     }

     static createEmptyMessageElement(message)
     {
         var emptyMessageElement = document.createElement("div");
         emptyMessageElement.className = "empty-message";
         emptyMessageElement.textContent = message;
         return emptyMessageElement;
     }

     static get showMoreFetchCount() { return 100; }

     static addShowMoreIfNeeded({resolvedValue, representation, parentTreeElement, handleShowMoreClicked, handleShowAllClicked})
     {
         console.assert(resolvedValue instanceof WI.RemoteObject, resolvedValue);
         console.assert(resolvedValue.isArray() || resolvedValue.isCollectionType());
         console.assert(typeof resolvedValue.size === "number" && resolvedValue.size > 0, resolvedValue);
         console.assert("_fetchStart" in representation, representation);
         console.assert("_fetchEnd" in representation, representation);
         console.assert("_fetchEndIndex" in representation, representation);
         console.assert(typeof handleShowMoreClicked === "function", handleShowMoreClicked);
         console.assert(typeof handleShowAllClicked === "function", handleShowAllClicked);

         // COMPATIBILITY (iOS 13): Runtime.getProperties/Runtime.getDisplayableProperties didn't support `fetchStart`/`fetchCount` yet.
         if (!InspectorBackend.domains.Runtime.getProperties.supports("fetchStart"))
             return;

         let remaining = resolvedValue.size - representation._fetchEnd;
         if (remaining <= 0)
             return;

         let treeElement = new WI.TreeElement(document.createElement("span"));
         treeElement.selectable = false;
         parentTreeElement.insertChild(treeElement, representation._fetchEndIndex);

         // FIXME: <https://webkit.org/b/201965> Web Inspector: allow examining items in the middle of an array/collection without having to show all items before

         let buttons = [];
         let createButton = (textContent, handleClick) => {
             let button = treeElement.title.appendChild(document.createElement("button"));
             button.textContent = textContent;
             button.addEventListener("click", (event) => {
                 event.stop();

                 representation.singleFireEventListener(ObjectTreeView.Event.Updated, () => {
                     // The `treeElement` may have already been removed by some other means (e.g. `removeChildren`).
                     if (treeElement.parent === parentTreeElement)
                         parentTreeElement.removeChild(treeElement);
                 });

                 for (let other of buttons)
                     other.disabled = true;

                 let spinner = new WI.IndeterminateProgressSpinner;
                 button.insertAdjacentElement("afterend", spinner.element);

                 handleClick();
             });
             buttons.push(button);
         };

         if (!resolvedValue.isWeakCollection() && remaining > ObjectTreeView.showMoreFetchCount) {
             createButton(WI.UIString("Show %d More").format(ObjectTreeView.showMoreFetchCount), () => {
                 representation._fetchStart = representation._fetchEnd;
                 representation._fetchEnd = representation._fetchStart + ObjectTreeView.showMoreFetchCount;
                 handleShowMoreClicked();
             });
         }

         createButton(WI.UIString("Show All (%d More)").format(remaining), () => {
             representation._fetchStart = 0;
             representation._fetchEnd = Infinity;
             representation._fetchEndIndex = 0;
             handleShowAllClicked();
         });
     }

     static comparePropertyDescriptors(propertyA, propertyB)
     {
         var a = propertyA.name;
         var b = propertyB.name;

         // Put __proto__ at the bottom.
         if (a === "__proto__")
             return 1;
         if (b === "__proto__")
             return -1;

         // Put Internal properties at the top.
         if (propertyA.isInternalProperty && !propertyB.isInternalProperty)
             return -1;
         if (propertyB.isInternalProperty && !propertyA.isInternalProperty)
             return 1;

         // Put Symbol properties at the bottom.
         if (propertyA.symbol && !propertyB.symbol)
             return 1;
         if (propertyB.symbol && !propertyA.symbol)
             return -1;

         // Symbol properties may have the same description string but be different objects.
         if (a === b)
             return 0;

         var diff = 0;
         var chunk = /^\d+|^\D+/;
         var chunka, chunkb, anum, bnum;
         while (diff === 0) {
             if (!a && b)
                 return -1;
             if (!b && a)
                 return 1;
             chunka = a.match(chunk)[0];
             chunkb = b.match(chunk)[0];
             anum = !isNaN(chunka);
             bnum = !isNaN(chunkb);
             if (anum && !bnum)
                 return -1;
             if (bnum && !anum)
                 return 1;
             if (anum && bnum) {
                 diff = chunka - chunkb;
                 if (diff === 0 && chunka.length !== chunkb.length) {
                     if (!+chunka && !+chunkb) // chunks are strings of all 0s (special case)
                         return chunka.length - chunkb.length;
                     else
                         return chunkb.length - chunka.length;
                 }
             } else if (chunka !== chunkb)
                 return chunka < chunkb ? -1 : 1;
             a = a.substring(chunka.length);
             b = b.substring(chunkb.length);
         }
         return diff;
     }

     // Public

     get object()
     {
         return this._object;
     }

     get element()
     {
         return this._element;
     }

     get treeOutline()
     {
         return this._outline;
     }

     get expanded()
     {
         return this._expanded;
     }

     expand()
     {
         if (this._expanded)
             return;

         if (this._hasLosslessPreview)
             return;

         this._expanded = true;
         this._element.classList.add("expanded");

         if (this._previewView)
             this._previewView.showTitle();

         this._trackWeakEntries();

         this.update();
     }

     collapse()
     {
         if (!this._expanded)
             return;

         this._expanded = false;
         this._element.classList.remove("expanded");

         if (this._previewView)
             this._previewView.showPreview();

         this._untrackWeakEntries();
     }

     showOnlyProperties()
     {
         this._inConsole = false;

         this._element.classList.add("properties-only");

         this._includeProtoProperty = false;
     }

     showOnlyJSON()
     {
         this.showOnlyProperties();

         this._element.classList.add("json-only");
     }

     appendTitleSuffix(suffixElement)
     {
         if (this._previewView)
             this._previewView.element.appendChild(suffixElement);
         else
             this._titleElement.appendChild(suffixElement);
     }

     appendExtraPropertyDescriptor(propertyDescriptor)
     {
         if (!this._extraProperties)
             this._extraProperties = [];

         this._extraProperties.push(propertyDescriptor);
     }

     setPrototypeNameOverride(override)
     {
         this._prototypeNameOverride = override;
     }

     // Protected

     update()
     {
         this._fetchStart = 0;
         this._fetchEndIndex = 0;
         this._updateChildren();
     }

     // Private

     _updateChildren()
     {
         let options = {
             ownProperties: true,
             generatePreview: true,
         };

         if (isFinite(this._fetchEnd) && this._fetchEnd < this._object.size) {
             options.fetchStart = this._fetchStart;
             options.fetchCount = this._fetchEnd - this._fetchStart;
         }

         let wrap = (handler) => (list) => {
             if (this._fetchEndIndex === 0)
                 this._outline.removeChildren();

             if (!list) {
                 let errorMessageElement = WI.ObjectTreeView.createEmptyMessageElement(WI.UIString("Could not fetch properties. Object may no longer exist."));
                 this._outline.appendChild(new WI.TreeElement(errorMessageElement));
                 return;
             }

             handler.call(this, list, this._propertyPath);

             this.dispatchEventToListeners(ObjectTreeView.Event.Updated);
         };

         if (this._object.isCollectionType() && this._mode === ObjectTreeView.Mode.Properties)
             this._object.getCollectionEntries(wrap(this._updateEntries), options);
         else if (this._object.isClass())
             this._object.classPrototype.getDisplayablePropertyDescriptors(wrap(this._updateProperties), options);
         else if (this._mode === ObjectTreeView.Mode.PureAPI)
             this._object.getPropertyDescriptors(wrap(this._updateProperties), options);
         else
             this._object.getDisplayablePropertyDescriptors(wrap(this._updateProperties), options);
     }

     _updateEntries(entries, propertyPath)
     {
         entries.forEach((entry, i) => {
             if (entry.key) {
                 this._outline.insertChild(new WI.ObjectTreeMapKeyTreeElement(entry.key, propertyPath), this._fetchEndIndex++);
                 this._outline.insertChild(new WI.ObjectTreeMapValueTreeElement(entry.value, propertyPath, entry.key), this._fetchEndIndex++);
             } else
                 this._outline.insertChild(new WI.ObjectTreeSetIndexTreeElement(entry.value, propertyPath), this._fetchEndIndex++);
         });

         if (!this._outline.children.length) {
             let emptyMessageElement = ObjectTreeView.createEmptyMessageElement(WI.UIString("No Entries"));
             this._outline.appendChild(new WI.TreeElement(emptyMessageElement));
         } else {
             console.assert(this._mode === WI.ObjectTreeView.Mode.Properties);
             ObjectTreeView.addShowMoreIfNeeded({
                 resolvedValue: this._object,
                 representation: this,
                 parentTreeElement: this._outline,
                 handleShowMoreClicked: () => {
                     this._updateChildren();
                 },
                 handleShowAllClicked: () => {
                     this.update();
                 },
             });
         }

         // Show the prototype so users can see the API, but only fetch it the first time.
         if (this._fetchStart === 0) {
             this._object.getOwnPropertyDescriptor("__proto__", (propertyDescriptor) => {
                 if (propertyDescriptor)
                     this._outline.appendChild(new WI.ObjectTreePropertyTreeElement(propertyDescriptor, propertyPath, this._mode));
             });
         }
     }

     _updateProperties(properties, propertyPath)
     {
         if (this._extraProperties)
             properties.pushAll(this._extraProperties);

         properties.sort(WI.ObjectTreeView.comparePropertyDescriptors);

         var isArray = this._object.isArray();
         var isPropertyMode = this._mode === WI.ObjectTreeView.Mode.Properties;

         var hadProto = false;
         for (var propertyDescriptor of properties) {
             if (propertyDescriptor.name === "__proto__") {
                 // COMPATIBILITY (iOS 8): Sometimes __proto__ is not a value, but a get/set property.
                 // In those cases it is actually not useful to show.
                 if (!propertyDescriptor.hasValue())
                     continue;
                 if (!this._includeProtoProperty)
                     continue;
                 hadProto = true;
                 this._outline.appendChild(new WI.ObjectTreePropertyTreeElement(propertyDescriptor, propertyPath, this._mode, this._prototypeNameOverride));
                 continue;
             }

             if (isArray && isPropertyMode) {
                 if (propertyDescriptor.isIndexProperty())
                     this._outline.insertChild(new WI.ObjectTreeArrayIndexTreeElement(propertyDescriptor, propertyPath), this._fetchEndIndex++);
             } else
                 this._outline.insertChild(new WI.ObjectTreePropertyTreeElement(propertyDescriptor, propertyPath, this._mode, this._prototypeNameOverride), this._fetchEndIndex++);
         }

         if (!this._outline.children.length || (hadProto && this._outline.children.length === 1)) {
             let emptyMessageElement = ObjectTreeView.createEmptyMessageElement(WI.UIString("No Properties"));
             this._outline.insertChild(new WI.TreeElement(emptyMessageElement), 0);
         } else if (isArray && isPropertyMode) {
             ObjectTreeView.addShowMoreIfNeeded({
                 resolvedValue: this._object,
                 representation: this,
                 parentTreeElement: this._outline,
                 handleShowMoreClicked: () => {
                     this._updateChildren();
                 },
                 handleShowAllClicked: () => {
                     this.update();
                 },
             });
         }
     }

     _handlePreviewOrTitleElementClick(event)
     {
         if (this._hasLosslessPreview)
             return;

         if (!this._expanded)
             this.expand();
         else
             this.collapse();

         event.stopPropagation();
     }

     _trackWeakEntries()
     {
         if (this._trackingEntries)
             return;

         if (!this._object.isWeakCollection())
             return;

         this._trackingEntries = true;

         if (this._inConsole) {
             WI.consoleManager.addEventListener(WI.ConsoleManager.Event.Cleared, this._untrackWeakEntries, this);
             WI.consoleManager.addEventListener(WI.ConsoleManager.Event.SessionStarted, this._untrackWeakEntries, this);
         }
     }

     _untrackWeakEntries()
     {
         if (!this._trackingEntries)
             return;

         if (!this._object.isWeakCollection())
             return;

         this._trackingEntries = false;

         this._object.releaseWeakCollectionEntries();

         if (this._inConsole) {
             WI.consoleManager.removeEventListener(WI.ConsoleManager.Event.Cleared, this._untrackWeakEntries, this);
             WI.consoleManager.removeEventListener(WI.ConsoleManager.Event.SessionStarted, this._untrackWeakEntries, this);
         }

         // FIXME: This only tries to release weak entries if this object was a WeakMap.
         // If there was a WeakMap expanded in a sub-object, we will never release those values.
         // Should we attempt walking the entire tree and release weak collections?
     }
 };

 WI.ObjectTreeView.Mode = {
     Properties: Symbol("object-tree-properties"),      // Properties
     PrototypeAPI: Symbol("object-tree-prototype-api"), // API view on a live object instance, so getters can be invoked.
     ClassAPI: Symbol("object-tree-class-api"),         // API view without an object instance, can not invoke getters.
     PureAPI: Symbol("object-tree-pure-api"),           // API view without special displayable property handling, just own properties. Getters can be invoked if the property path has a non-prototype object.
 };

 WI.ObjectTreeView.Event = {
     Updated: "object-tree-updated",
 };
	/*
	* Copyright (C) 2015 Apple 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:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. 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.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS 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 APPLE INC. OR ITS 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.
	*/

	WI.ObjectTreeView = class ObjectTreeView extends WI.Object
	{
	constructor(object, mode, propertyPath, forceExpanding)
	{
	super();

	console.assert(object instanceof WI.RemoteObject);
	console.assert(!propertyPath \|\| propertyPath instanceof WI.PropertyPath);

	var providedPropertyPath = propertyPath instanceof WI.PropertyPath;

	this._object = object;
	this._mode = mode \|\| WI.ObjectTreeView.defaultModeForObject(object);
	this._propertyPath = propertyPath \|\| new WI.PropertyPath(this._object, "this");
	this._expanded = false;
	this._hasLosslessPreview = false;
	this._includeProtoProperty = true;

	// If ObjectTree is used outside of the console, we do not know when to release
	// WeakMap entries. Currently collapse would work. For the console, we can just
	// listen for console clear events. Currently all ObjectTrees are in the console.
	this._inConsole = true;

	this._fetchStart = 0;
	this._fetchEnd = ObjectTreeView.showMoreFetchCount;
	this._fetchEndIndex = 0;

	// Always force expanding for classes.
	if (this._object.isClass())
	forceExpanding = true;

	this._element = document.createElement("div");
	this._element.__objectTree = this;
	this._element.className = "object-tree";

	if (this._object.preview) {
	this._previewView = new WI.ObjectPreviewView(this._object, this._object.preview);
	this._previewView.setOriginatingObjectInfo(this._object, providedPropertyPath ? propertyPath : null);
	this._previewView.element.addEventListener("click", this._handlePreviewOrTitleElementClick.bind(this));
	this._element.appendChild(this._previewView.element);

	if (this._previewView.lossless && !this._propertyPath.parent && !forceExpanding) {
	this._hasLosslessPreview = true;
	this.element.classList.add("lossless-preview");
	}
	} else {
	this._titleElement = document.createElement("span");
	this._titleElement.className = "title";
	this._titleElement.appendChild(WI.FormattedValue.createElementForRemoteObject(this._object));
	this._titleElement.addEventListener("click", this._handlePreviewOrTitleElementClick.bind(this));
	this._element.appendChild(this._titleElement);
	}

	this._outline = new WI.TreeOutline;
	this._outline.compact = true;
	this._outline.customIndent = true;
	this._outline.element.classList.add("object");
	this._element.appendChild(this._outline.element);

	// FIXME: Support editable ObjectTrees.
	}

	// Static

	static defaultModeForObject(object)
	{
	if (object.subtype === "class")
	return WI.ObjectTreeView.Mode.ClassAPI;

	return WI.ObjectTreeView.Mode.Properties;
	}

	static createEmptyMessageElement(message)
	{
	var emptyMessageElement = document.createElement("div");
	emptyMessageElement.className = "empty-message";
	emptyMessageElement.textContent = message;
	return emptyMessageElement;
	}

	static get showMoreFetchCount() { return 100; }

	static addShowMoreIfNeeded({resolvedValue, representation, parentTreeElement, handleShowMoreClicked, handleShowAllClicked})
	{
	console.assert(resolvedValue instanceof WI.RemoteObject, resolvedValue);
	console.assert(resolvedValue.isArray() \|\| resolvedValue.isCollectionType());
	console.assert(typeof resolvedValue.size === "number" && resolvedValue.size > 0, resolvedValue);
	console.assert("_fetchStart" in representation, representation);
	console.assert("_fetchEnd" in representation, representation);
	console.assert("_fetchEndIndex" in representation, representation);
	console.assert(typeof handleShowMoreClicked === "function", handleShowMoreClicked);
	console.assert(typeof handleShowAllClicked === "function", handleShowAllClicked);

	// COMPATIBILITY (iOS 13): Runtime.getProperties/Runtime.getDisplayableProperties didn't support `fetchStart`/`fetchCount` yet.
	if (!InspectorBackend.domains.Runtime.getProperties.supports("fetchStart"))
	return;

	let remaining = resolvedValue.size - representation._fetchEnd;
	if (remaining <= 0)
	return;

	let treeElement = new WI.TreeElement(document.createElement("span"));
	treeElement.selectable = false;
	parentTreeElement.insertChild(treeElement, representation._fetchEndIndex);

	// FIXME: <https://webkit.org/b/201965> Web Inspector: allow examining items in the middle of an array/collection without having to show all items before

	let buttons = [];
	let createButton = (textContent, handleClick) => {
	let button = treeElement.title.appendChild(document.createElement("button"));
	button.textContent = textContent;
	button.addEventListener("click", (event) => {
	event.stop();

	representation.singleFireEventListener(ObjectTreeView.Event.Updated, () => {
	// The `treeElement` may have already been removed by some other means (e.g. `removeChildren`).
	if (treeElement.parent === parentTreeElement)
	parentTreeElement.removeChild(treeElement);
	});

	for (let other of buttons)
	other.disabled = true;

	let spinner = new WI.IndeterminateProgressSpinner;
	button.insertAdjacentElement("afterend", spinner.element);

	handleClick();
	});
	buttons.push(button);
	};

	if (!resolvedValue.isWeakCollection() && remaining > ObjectTreeView.showMoreFetchCount) {
	createButton(WI.UIString("Show %d More").format(ObjectTreeView.showMoreFetchCount), () => {
	representation._fetchStart = representation._fetchEnd;
	representation._fetchEnd = representation._fetchStart + ObjectTreeView.showMoreFetchCount;
	handleShowMoreClicked();
	});
	}

	createButton(WI.UIString("Show All (%d More)").format(remaining), () => {
	representation._fetchStart = 0;
	representation._fetchEnd = Infinity;
	representation._fetchEndIndex = 0;
	handleShowAllClicked();
	});
	}

	static comparePropertyDescriptors(propertyA, propertyB)
	{
	var a = propertyA.name;
	var b = propertyB.name;

	// Put __proto__ at the bottom.
	if (a === "__proto__")
	return 1;
	if (b === "__proto__")
	return -1;

	// Put Internal properties at the top.
	if (propertyA.isInternalProperty && !propertyB.isInternalProperty)
	return -1;
	if (propertyB.isInternalProperty && !propertyA.isInternalProperty)
	return 1;

	// Put Symbol properties at the bottom.
	if (propertyA.symbol && !propertyB.symbol)
	return 1;
	if (propertyB.symbol && !propertyA.symbol)
	return -1;

	// Symbol properties may have the same description string but be different objects.
	if (a === b)
	return 0;

	var diff = 0;
	var chunk = /^\d+\|^\D+/;
	var chunka, chunkb, anum, bnum;
	while (diff === 0) {
	if (!a && b)
	return -1;
	if (!b && a)
	return 1;
	chunka = a.match(chunk)[0];
	chunkb = b.match(chunk)[0];
	anum = !isNaN(chunka);
	bnum = !isNaN(chunkb);
	if (anum && !bnum)
	return -1;
	if (bnum && !anum)
	return 1;
	if (anum && bnum) {
	diff = chunka - chunkb;
	if (diff === 0 && chunka.length !== chunkb.length) {
	if (!+chunka && !+chunkb) // chunks are strings of all 0s (special case)
	return chunka.length - chunkb.length;
	else
	return chunkb.length - chunka.length;
	}
	} else if (chunka !== chunkb)
	return chunka < chunkb ? -1 : 1;
	a = a.substring(chunka.length);
	b = b.substring(chunkb.length);
	}
	return diff;
	}

	// Public

	get object()
	{
	return this._object;
	}

	get element()
	{
	return this._element;
	}

	get treeOutline()
	{
	return this._outline;
	}

	get expanded()
	{
	return this._expanded;
	}

	expand()
	{
	if (this._expanded)
	return;

	if (this._hasLosslessPreview)
	return;

	this._expanded = true;
	this._element.classList.add("expanded");

	if (this._previewView)
	this._previewView.showTitle();

	this._trackWeakEntries();

	this.update();
	}

	collapse()
	{
	if (!this._expanded)
	return;

	this._expanded = false;
	this._element.classList.remove("expanded");

	if (this._previewView)
	this._previewView.showPreview();

	this._untrackWeakEntries();
	}

	showOnlyProperties()
	{
	this._inConsole = false;

	this._element.classList.add("properties-only");

	this._includeProtoProperty = false;
	}

	showOnlyJSON()
	{
	this.showOnlyProperties();

	this._element.classList.add("json-only");
	}

	appendTitleSuffix(suffixElement)
	{
	if (this._previewView)
	this._previewView.element.appendChild(suffixElement);
	else
	this._titleElement.appendChild(suffixElement);
	}

	appendExtraPropertyDescriptor(propertyDescriptor)
	{
	if (!this._extraProperties)
	this._extraProperties = [];

	this._extraProperties.push(propertyDescriptor);
	}

	setPrototypeNameOverride(override)
	{
	this._prototypeNameOverride = override;
	}

	// Protected

	update()
	{
	this._fetchStart = 0;
	this._fetchEndIndex = 0;
	this._updateChildren();
	}

	// Private

	_updateChildren()
	{
	let options = {
	ownProperties: true,
	generatePreview: true,
	};

	if (isFinite(this._fetchEnd) && this._fetchEnd < this._object.size) {
	options.fetchStart = this._fetchStart;
	options.fetchCount = this._fetchEnd - this._fetchStart;
	}

	let wrap = (handler) => (list) => {
	if (this._fetchEndIndex === 0)
	this._outline.removeChildren();

	if (!list) {
	let errorMessageElement = WI.ObjectTreeView.createEmptyMessageElement(WI.UIString("Could not fetch properties. Object may no longer exist."));
	this._outline.appendChild(new WI.TreeElement(errorMessageElement));
	return;
	}

	handler.call(this, list, this._propertyPath);

	this.dispatchEventToListeners(ObjectTreeView.Event.Updated);
	};

	if (this._object.isCollectionType() && this._mode === ObjectTreeView.Mode.Properties)
	this._object.getCollectionEntries(wrap(this._updateEntries), options);
	else if (this._object.isClass())
	this._object.classPrototype.getDisplayablePropertyDescriptors(wrap(this._updateProperties), options);
	else if (this._mode === ObjectTreeView.Mode.PureAPI)
	this._object.getPropertyDescriptors(wrap(this._updateProperties), options);
	else
	this._object.getDisplayablePropertyDescriptors(wrap(this._updateProperties), options);
	}

	_updateEntries(entries, propertyPath)
	{
	entries.forEach((entry, i) => {
	if (entry.key) {
	this._outline.insertChild(new WI.ObjectTreeMapKeyTreeElement(entry.key, propertyPath), this._fetchEndIndex++);
	this._outline.insertChild(new WI.ObjectTreeMapValueTreeElement(entry.value, propertyPath, entry.key), this._fetchEndIndex++);
	} else
	this._outline.insertChild(new WI.ObjectTreeSetIndexTreeElement(entry.value, propertyPath), this._fetchEndIndex++);
	});

	if (!this._outline.children.length) {
	let emptyMessageElement = ObjectTreeView.createEmptyMessageElement(WI.UIString("No Entries"));
	this._outline.appendChild(new WI.TreeElement(emptyMessageElement));
	} else {
	console.assert(this._mode === WI.ObjectTreeView.Mode.Properties);
	ObjectTreeView.addShowMoreIfNeeded({
	resolvedValue: this._object,
	representation: this,
	parentTreeElement: this._outline,
	handleShowMoreClicked: () => {
	this._updateChildren();
	},
	handleShowAllClicked: () => {
	this.update();
	},
	});
	}

	// Show the prototype so users can see the API, but only fetch it the first time.
	if (this._fetchStart === 0) {
	this._object.getOwnPropertyDescriptor("__proto__", (propertyDescriptor) => {
	if (propertyDescriptor)
	this._outline.appendChild(new WI.ObjectTreePropertyTreeElement(propertyDescriptor, propertyPath, this._mode));
	});
	}
	}

	_updateProperties(properties, propertyPath)
	{
	if (this._extraProperties)
	properties.pushAll(this._extraProperties);

	properties.sort(WI.ObjectTreeView.comparePropertyDescriptors);

	var isArray = this._object.isArray();
	var isPropertyMode = this._mode === WI.ObjectTreeView.Mode.Properties;

	var hadProto = false;
	for (var propertyDescriptor of properties) {
	if (propertyDescriptor.name === "__proto__") {
	// COMPATIBILITY (iOS 8): Sometimes __proto__ is not a value, but a get/set property.
	// In those cases it is actually not useful to show.
	if (!propertyDescriptor.hasValue())
	continue;
	if (!this._includeProtoProperty)
	continue;
	hadProto = true;
	this._outline.appendChild(new WI.ObjectTreePropertyTreeElement(propertyDescriptor, propertyPath, this._mode, this._prototypeNameOverride));
	continue;
	}

	if (isArray && isPropertyMode) {
	if (propertyDescriptor.isIndexProperty())
	this._outline.insertChild(new WI.ObjectTreeArrayIndexTreeElement(propertyDescriptor, propertyPath), this._fetchEndIndex++);
	} else
	this._outline.insertChild(new WI.ObjectTreePropertyTreeElement(propertyDescriptor, propertyPath, this._mode, this._prototypeNameOverride), this._fetchEndIndex++);
	}

	if (!this._outline.children.length \|\| (hadProto && this._outline.children.length === 1)) {
	let emptyMessageElement = ObjectTreeView.createEmptyMessageElement(WI.UIString("No Properties"));
	this._outline.insertChild(new WI.TreeElement(emptyMessageElement), 0);
	} else if (isArray && isPropertyMode) {
	ObjectTreeView.addShowMoreIfNeeded({
	resolvedValue: this._object,
	representation: this,
	parentTreeElement: this._outline,
	handleShowMoreClicked: () => {
	this._updateChildren();
	},
	handleShowAllClicked: () => {
	this.update();
	},
	});
	}
	}

	_handlePreviewOrTitleElementClick(event)
	{
	if (this._hasLosslessPreview)
	return;

	if (!this._expanded)
	this.expand();
	else
	this.collapse();

	event.stopPropagation();
	}

	_trackWeakEntries()
	{
	if (this._trackingEntries)
	return;

	if (!this._object.isWeakCollection())
	return;

	this._trackingEntries = true;

	if (this._inConsole) {
	WI.consoleManager.addEventListener(WI.ConsoleManager.Event.Cleared, this._untrackWeakEntries, this);
	WI.consoleManager.addEventListener(WI.ConsoleManager.Event.SessionStarted, this._untrackWeakEntries, this);
	}
	}

	_untrackWeakEntries()
	{
	if (!this._trackingEntries)
	return;

	if (!this._object.isWeakCollection())
	return;

	this._trackingEntries = false;

	this._object.releaseWeakCollectionEntries();

	if (this._inConsole) {
	WI.consoleManager.removeEventListener(WI.ConsoleManager.Event.Cleared, this._untrackWeakEntries, this);
	WI.consoleManager.removeEventListener(WI.ConsoleManager.Event.SessionStarted, this._untrackWeakEntries, this);
	}

	// FIXME: This only tries to release weak entries if this object was a WeakMap.
	// If there was a WeakMap expanded in a sub-object, we will never release those values.
	// Should we attempt walking the entire tree and release weak collections?
	}
	};

	WI.ObjectTreeView.Mode = {
	Properties: Symbol("object-tree-properties"), // Properties
	PrototypeAPI: Symbol("object-tree-prototype-api"), // API view on a live object instance, so getters can be invoked.
	ClassAPI: Symbol("object-tree-class-api"), // API view without an object instance, can not invoke getters.
	PureAPI: Symbol("object-tree-pure-api"), // API view without special displayable property handling, just own properties. Getters can be invoked if the property path has a non-prototype object.
	};

	WI.ObjectTreeView.Event = {
	Updated: "object-tree-updated",
	};