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node_modules/nwmatcher/src/modules/nwmatcher-cache.js
Maintainability
67.86
Lines of code
169
Difficulty
40.26
Estimated Errors
1.16
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/* * Copyright (C) 2007-2015 Diego Perini * All rights reserved. * * Caching/memoization module for NWMatcher * * Added capabilities: * * - Mutation Events are feature tested and used safely * - handle caching different document types HTML/XML/SVG * - store result sets for different selectors / contexts * - simultaneously control mutation on multiple documents * */ (function(global) { // export the public API for CommonJS implementations, // for headless JS engines or for standard web browsers var Dom = // as CommonJS/NodeJS module typeof exports == 'object' ? exports : // create or extend NW namespace ((global.NW || (global.NW = global.Object())) && (global.NW.Dom || (global.NW.Dom = global.Object()))), Contexts = global.Object(), Results = global.Object(), isEnabled = false, isExpired = true, isPaused = false, context = global.document, root = context.documentElement, // last time cache initialization was called lastCalled = 0, // minimum time allowed between calls to the cache initialization minCacheRest = 15, //ms mutationTest = function(type, callback) { var isSupported = false, root = document.documentElement, div = document.createElement('div'), handler = function() { isSupported = true; }; root.insertBefore(div, root.firstChild); div.addEventListener(type, handler, true); if (callback && callback.call) callback(div); div.removeEventListener(type, handler, true); root.removeChild(div); return isSupported; }, // check for Mutation Events, DOMAttrModified should be // enough to ensure DOMNodeInserted/DOMNodeRemoved exist HACKED_MUTATION_EVENTS = false, NATIVE_MUTATION_EVENTS = root.addEventListener ? mutationTest('DOMAttrModified', function(e) { e.setAttribute('id', 'nw'); }) : false, loadResults = function(selector, from, doc, root) { if (isEnabled && !isPaused) { if (!isExpired) { if (Results[selector] && Contexts[selector] === from) { return Results[selector]; } } else { // pause caching while we are getting // hammered by dom mutations (jdalton) now = (new global.Date).getTime(); if ((now - lastCalled) < minCacheRest) { isPaused = isExpired = true; global.setTimeout(function() { isPaused = false; }, minCacheRest); } else setCache(true, doc); lastCalled = now; } } return undefined; }, saveResults = function(selector, from, doc, data) { Contexts[selector] = from; Results[selector] = data; return; }, /*-------------------------------- CACHING ---------------------------------*/ // invoked by mutation events to expire cached parts mutationWrapper = function(event) { var d = event.target.ownerDocument || event.target; stopMutation(d); expireCache(d); }, // append mutation events startMutation = function(d) { if (!d.isCaching && d.addEventListener) { // FireFox/Opera/Safari/KHTML have support for Mutation Events d.addEventListener('DOMAttrModified', mutationWrapper, true); d.addEventListener('DOMNodeInserted', mutationWrapper, true); d.addEventListener('DOMNodeRemoved', mutationWrapper, true); d.isCaching = true; } }, // remove mutation events stopMutation = function(d) { if (d.isCaching && d.removeEventListener) { d.removeEventListener('DOMAttrModified', mutationWrapper, true); d.removeEventListener('DOMNodeInserted', mutationWrapper, true); d.removeEventListener('DOMNodeRemoved', mutationWrapper, true); d.isCaching = false; } }, // enable/disable context caching system // @d optional document context (iframe, xml document) // script loading context will be used as default context setCache = function(enable, d) { if (!!enable) { isExpired = false; startMutation(d); } else { isExpired = true; stopMutation(d); } isEnabled = !!enable; }, // expire complete cache // can be invoked by Mutation Events or // programmatically by other code/scripts // document context is mandatory no checks expireCache = function(d) { isExpired = true; Contexts = global.Object(); Results = global.Object(); }; if (!NATIVE_MUTATION_EVENTS && root.addEventListener && Element && Element.prototype) { if (mutationTest('DOMNodeInserted', function(e) { e.appendChild(document.createElement('div')); }) && mutationTest('DOMNodeRemoved', function(e) { e.removeChild(e.appendChild(document.createElement('div'))); })) { HACKED_MUTATION_EVENTS = true; Element.prototype._setAttribute = Element.prototype.setAttribute; Element.prototype.setAttribute = function(name, val) { this._setAttribute(name, val); mutationWrapper({ target: this, type: 'DOMAttrModified', attrName: name, attrValue: val }); }; } } isEnabled = NATIVE_MUTATION_EVENTS || HACKED_MUTATION_EVENTS; /*------------------------------- PUBLIC API -------------------------------*/ // save results into cache Dom.saveResults = saveResults; // load results from cache Dom.loadResults = loadResults; // expire DOM tree cache Dom.expireCache = expireCache; // enable/disable cache Dom.setCache = setCache; })(this);