2bd4904ead
This adds a `DOMParser`-based XML reader which emits events like a SAX XML reader for compatibility with the feed processor.
140 lines
3.6 KiB
JavaScript
140 lines
3.6 KiB
JavaScript
/*
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***** BEGIN LICENSE BLOCK *****
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Copyright © 2021 Corporation for Digital Scholarship
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Vienna, Virginia, USA
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https://www.zotero.org
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This file is part of Zotero.
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Zotero is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Zotero is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with Zotero. If not, see <http://www.gnu.org/licenses/>.
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***** END LICENSE BLOCK *****
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*/
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"use strict";
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/**
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* This implements `nsISAXXMLReader` using content-accessible APIs, such as `DOMParser` and
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* `TreeWalker`. It should be usable in any web platform environment that supports those standard
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* APIs.
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*
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* Note that while this class implements a SAX-style API (which usually implies streaming style
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* parsing for documents of any length), this class actually uses whole document parsing internally.
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* Instead, `DOMParser` reads the entire document and this walks the resulting DOM. Thus, this class
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* is mainly useful only for smaller documents where it's useful to conform to SAX-style API to
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* support existing code.
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*
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* Higher-level components are notified of XML content via the `nsISAXContentHandler` and
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* `nsISAXErrorHandler` interfaces as this reader walks through the XML content.
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*/
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class SAXXMLReader {
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constructor() {
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this.contentHandler = null;
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this.errorHandler = null;
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this.baseURI = null;
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this._data = null;
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this._walker = null;
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}
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// nsISAXXMLReader
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parseAsync(requestObserver) {
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if (requestObserver) {
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throw new Error("requestObserver argument parseAsync is not currently supported");
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}
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}
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// Fetch API
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async onResponseAvailable(response) {
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if (!response.ok) {
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throw new Error("Unable to fetch data");
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}
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this._data = await response.text();
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this._parseAndNotify();
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}
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// Parsing and notification
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_parseAndNotify() {
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if (!this.contentHandler) {
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return;
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}
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const doc = new DOMParser().parseFromString(this._data, "text/xml");
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this._walker = doc.createTreeWalker(doc.documentElement);
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this.contentHandler.startDocument();
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this._walk();
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this.contentHandler.endDocument();
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this._data = null;
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this._walker = null;
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}
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_walk() {
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const node = this._walker.currentNode;
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switch (node.nodeType) {
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// ELEMENT_NODE
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case 1: {
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this.contentHandler.startElement(
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node.namespaceURI,
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node.localName,
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"", // qualifed names are not used
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node.attributes,
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);
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// Try to move down
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if (this._walker.firstChild()) {
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this._walk();
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// Move up
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this._walker.parentNode();
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}
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this.contentHandler.endElement(
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node.namespaceURI,
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node.localName,
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"", // qualifed names are not used
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);
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break;
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}
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// TEXT_NODE
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case 3: {
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this.contentHandler.characters(node.data);
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break;
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}
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// CDATA_SECTION_NODE
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case 4: {
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this.contentHandler.characters(node.data);
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break;
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}
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// PROCESSING_INSTRUCTION_NODE
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case 7: {
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this.contentHandler.processingInstruction(node.target, node.data);
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break;
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}
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}
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// Try to move across
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if (this._walker.nextSibling()) {
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this._walk();
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}
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}
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}
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if (typeof module == "object") {
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module.exports = SAXXMLReader;
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}
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