ref: 50ad979b5dc99c2499a3b80d3318c2a4c6430b28
dir: /domino-lib/FilteredElementList.js/
"use strict"; module.exports = FilteredElementList; var Node = require('./Node'); // // This file defines node list implementation that lazily traverses // the document tree (or a subtree rooted at any element) and includes // only those elements for which a specified filter function returns true. // It is used to implement the // {Document,Element}.getElementsBy{TagName,ClassName}{,NS} methods. // // XXX this should inherit from NodeList function FilteredElementList(root, filter) { this.root = root; this.filter = filter; this.lastModTime = root.lastModTime; this.done = false; this.cache = []; this.traverse(); } FilteredElementList.prototype = Object.create(Object.prototype, { length: { get: function() { this.checkcache(); if (!this.done) this.traverse(); return this.cache.length; } }, item: { value: function(n) { this.checkcache(); if (!this.done && n >= this.cache.length) { // This can lead to O(N^2) behavior if we stop when we get to n // and the caller is iterating through the items in order; so // be sure to do the full traverse here. this.traverse(/*n*/); } return this.cache[n]; } }, checkcache: { value: function() { if (this.lastModTime !== this.root.lastModTime) { // subtree has changed, so invalidate cache for (var i = this.cache.length-1; i>=0; i--) { this[i] = undefined; } this.cache.length = 0; this.done = false; this.lastModTime = this.root.lastModTime; } } }, // If n is specified, then traverse the tree until we've found the nth // item (or until we've found all items). If n is not specified, // traverse until we've found all items. traverse: { value: function(n) { // increment n so we can compare to length, and so it is never falsy if (n !== undefined) n++; var elt; while ((elt = this.next()) !== null) { this[this.cache.length] = elt; //XXX Use proxy instead this.cache.push(elt); if (n && this.cache.length === n) return; } // no next element, so we've found everything this.done = true; } }, // Return the next element under root that matches filter next: { value: function() { var start = (this.cache.length === 0) ? this.root // Start at the root or at : this.cache[this.cache.length-1]; // the last element we found var elt; if (start.nodeType === Node.DOCUMENT_NODE) elt = start.documentElement; else elt = start.nextElement(this.root); while(elt) { if (this.filter(elt)) { return elt; } elt = elt.nextElement(this.root); } return null; } }, });