120 lines
3.5 KiB
JavaScript
120 lines
3.5 KiB
JavaScript
/**
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* @author Toru Nagashima
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* @copyright 2015 Toru Nagashima. All rights reserved.
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* See LICENSE file in root directory for full license.
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*/
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"use strict";
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//-----------------------------------------------------------------------------
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// Requirements
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//-----------------------------------------------------------------------------
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var Commons = require("./commons");
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var LISTENERS = Commons.LISTENERS;
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var ATTRIBUTE = Commons.ATTRIBUTE;
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var newNode = Commons.newNode;
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//-----------------------------------------------------------------------------
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// Helpers
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//-----------------------------------------------------------------------------
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/**
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* Gets a specified attribute listener from a given EventTarget object.
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*
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* @param {EventTarget} eventTarget - An EventTarget object to get.
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* @param {string} type - An event type to get.
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* @returns {function|null} The found attribute listener.
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*/
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function getAttributeListener(eventTarget, type) {
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var node = eventTarget[LISTENERS][type];
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while (node != null) {
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if (node.kind === ATTRIBUTE) {
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return node.listener;
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}
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node = node.next;
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}
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return null;
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}
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/**
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* Sets a specified attribute listener to a given EventTarget object.
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*
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* @param {EventTarget} eventTarget - An EventTarget object to set.
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* @param {string} type - An event type to set.
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* @param {function|null} listener - A listener to be set.
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* @returns {void}
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*/
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function setAttributeListener(eventTarget, type, listener) {
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if (typeof listener !== "function" && typeof listener !== "object") {
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listener = null; // eslint-disable-line no-param-reassign
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}
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var prev = null;
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var node = eventTarget[LISTENERS][type];
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while (node != null) {
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if (node.kind === ATTRIBUTE) {
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// Remove old value.
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if (prev == null) {
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eventTarget[LISTENERS][type] = node.next;
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}
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else {
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prev.next = node.next;
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}
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}
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else {
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prev = node;
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}
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node = node.next;
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}
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// Add new value.
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if (listener != null) {
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if (prev == null) {
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eventTarget[LISTENERS][type] = newNode(listener, ATTRIBUTE);
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}
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else {
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prev.next = newNode(listener, ATTRIBUTE);
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}
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}
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}
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//-----------------------------------------------------------------------------
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// Public Interface
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//-----------------------------------------------------------------------------
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/**
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* Defines an `EventTarget` implementation which has `onfoobar` attributes.
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*
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* @param {EventTarget} EventTargetBase - A base implementation of EventTarget.
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* @param {string[]} types - A list of event types which are defined as attribute listeners.
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* @returns {EventTarget} The defined `EventTarget` implementation which has attribute listeners.
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*/
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exports.defineCustomEventTarget = function(EventTargetBase, types) {
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function EventTarget() {
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EventTargetBase.call(this);
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}
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var descripter = {
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constructor: {
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value: EventTarget,
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configurable: true,
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writable: true
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}
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};
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types.forEach(function(type) {
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descripter["on" + type] = {
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get: function() { return getAttributeListener(this, type); },
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set: function(listener) { setAttributeListener(this, type, listener); },
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configurable: true,
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enumerable: true
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};
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});
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EventTarget.prototype = Object.create(EventTargetBase.prototype, descripter);
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return EventTarget;
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};
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