NodeIterator-impl.js
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"use strict";
const { domSymbolTree } = require("../helpers/internal-constants");
const { filter, FILTER_ACCEPT } = require("./helpers");
exports.implementation = class NodeIteratorImpl {
constructor(globalObject, args, privateData) {
this._active = false;
this.root = privateData.root;
this.whatToShow = privateData.whatToShow;
this.filter = privateData.filter;
this._referenceNode = this.root;
this._pointerBeforeReferenceNode = true;
// This is used to deactive the NodeIterator if there are too many working in a Document at the same time.
// Without weak references, a JS implementation of NodeIterator will leak, since we can't know when to clean it up.
// This ensures we force a clean up of those beyond some maximum (specified by the Document).
this._working = true;
this._workingNodeIteratorsMax = privateData.workingNodeIteratorsMax;
this._globalObject = globalObject;
}
get referenceNode() {
this._throwIfNotWorking();
return this._referenceNode;
}
get pointerBeforeReferenceNode() {
this._throwIfNotWorking();
return this._pointerBeforeReferenceNode;
}
nextNode() {
this._throwIfNotWorking();
return this._traverse("next");
}
previousNode() {
this._throwIfNotWorking();
return this._traverse("previous");
}
detach() {
// Intentionally do nothing, per spec.
}
// Called by Documents.
_preRemovingSteps(toBeRemovedNode) {
// Second clause is https://github.com/whatwg/dom/issues/496
if (!toBeRemovedNode.contains(this._referenceNode) || toBeRemovedNode === this.root) {
return;
}
if (this._pointerBeforeReferenceNode) {
let next = null;
let candidateForNext = domSymbolTree.following(toBeRemovedNode, { skipChildren: true });
while (candidateForNext !== null) {
if (this.root.contains(candidateForNext)) {
next = candidateForNext;
break;
}
candidateForNext = domSymbolTree.following(candidateForNext, { skipChildren: true });
}
if (next !== null) {
this._referenceNode = next;
return;
}
this._pointerBeforeReferenceNode = false;
}
const { previousSibling } = toBeRemovedNode;
this._referenceNode = previousSibling === null ?
toBeRemovedNode.parentNode :
domSymbolTree.lastInclusiveDescendant(toBeRemovedNode.previousSibling);
}
// Only called by getters and methods that are affected by the pre-removing steps
_throwIfNotWorking() {
if (!this._working) {
throw Error(`This NodeIterator is no longer working. More than ${this._workingNodeIteratorsMax} iterators are ` +
`being used concurrently. You can increase the 'concurrentNodeIterators' option to make this error go away.`);
}
}
_traverse(direction) {
let node = this._referenceNode;
let beforeNode = this._pointerBeforeReferenceNode;
while (true) {
if (direction === "next") {
if (!beforeNode) {
node = domSymbolTree.following(node, { root: this.root });
if (!node) {
return null;
}
}
beforeNode = false;
} else if (direction === "previous") {
if (beforeNode) {
node = domSymbolTree.preceding(node, { root: this.root });
if (!node) {
return null;
}
}
beforeNode = true;
}
const result = filter(this, node);
if (result === FILTER_ACCEPT) {
break;
}
}
this._referenceNode = node;
this._pointerBeforeReferenceNode = beforeNode;
return node;
}
};