128 lines
4.4 KiB
JavaScript
128 lines
4.4 KiB
JavaScript
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import { html } from 'parse5';
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import { SAXParser, } from 'parse5-sax-parser';
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import { escapeText, escapeAttribute } from 'entities/lib/escape.js';
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/**
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* Streaming [SAX](https://en.wikipedia.org/wiki/Simple_API_for_XML)-style HTML rewriter.
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* A [transform stream](https://nodejs.org/api/stream.html#stream_class_stream_transform) (which means you can pipe _through_ it, see example).
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*
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* The rewriter uses the raw source representation of tokens if they are not modified by the user. Therefore, the resulting
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* HTML is not affected by parser error-recovery mechanisms as in a classical parsing-serialization roundtrip.
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*
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* @example
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*
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* ```js
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* const RewritingStream = require('parse5-html-rewriting-stream');
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* const http = require('http');
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* const fs = require('fs');
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*
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* const file = fs.createWriteStream('/home/google.com.html');
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* const rewriter = new RewritingStream();
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*
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* // Replace divs with spans
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* rewriter.on('startTag', startTag => {
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* if (startTag.tagName === 'span') {
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* startTag.tagName = 'div';
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* }
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*
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* rewriter.emitStartTag(startTag);
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* });
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*
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* rewriter.on('endTag', endTag => {
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* if (endTag.tagName === 'span') {
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* endTag.tagName = 'div';
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* }
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*
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* rewriter.emitEndTag(endTag);
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* });
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*
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* // Wrap all text nodes with an <i> tag
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* rewriter.on('text', (_, raw) => {
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* // Use the raw representation of text without HTML entities decoding
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* rewriter.emitRaw(`<i>${raw}</i>`);
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* });
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*
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* http.get('http://google.com', res => {
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* // Assumes response is UTF-8.
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* res.setEncoding('utf8');
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* // `RewritingStream` is a `Transform` stream, which means you can pipe
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* // through it.
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* res.pipe(rewriter).pipe(file);
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* });
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* ```
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*/
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export class RewritingStream extends SAXParser {
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/** Note: `sourceCodeLocationInfo` is always enabled. */
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constructor() {
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super({ sourceCodeLocationInfo: true });
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}
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_transformChunk(chunk) {
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// NOTE: ignore upstream return values as we want to push to
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// the `Writable` part of the `Transform` stream ourselves.
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super._transformChunk(chunk);
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return '';
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}
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_getRawHtml(location) {
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const { droppedBufferSize, html } = this.tokenizer.preprocessor;
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const start = location.startOffset - droppedBufferSize;
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const end = location.endOffset - droppedBufferSize;
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return html.slice(start, end);
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}
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// Events
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emitIfListenerExists(eventName, token) {
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if (!super.emitIfListenerExists(eventName, token)) {
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this.emitRaw(this._getRawHtml(token.sourceCodeLocation));
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}
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// NOTE: don't skip new lines after `<pre>` and other tags,
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// otherwise we'll have incorrect raw data.
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this.parserFeedbackSimulator.skipNextNewLine = false;
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return true;
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}
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// Emitter API
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_emitToken(eventName, token) {
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this.emit(eventName, token, this._getRawHtml(token.sourceCodeLocation));
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}
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/** Emits a serialized document type token into the output stream. */
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emitDoctype(token) {
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let res = `<!DOCTYPE ${token.name}`;
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if (token.publicId !== null) {
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res += ` PUBLIC "${token.publicId}"`;
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}
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else if (token.systemId !== null) {
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res += ' SYSTEM';
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}
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if (token.systemId !== null) {
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res += ` "${token.systemId}"`;
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}
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res += '>';
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this.push(res);
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}
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/** Emits a serialized start tag token into the output stream. */
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emitStartTag(token) {
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let res = `<${token.tagName}`;
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for (const attr of token.attrs) {
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res += ` ${attr.name}="${escapeAttribute(attr.value)}"`;
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}
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res += token.selfClosing ? '/>' : '>';
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this.push(res);
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}
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/** Emits a serialized end tag token into the output stream. */
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emitEndTag(token) {
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this.push(`</${token.tagName}>`);
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}
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/** Emits a serialized text token into the output stream. */
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emitText({ text }) {
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this.push(!this.parserFeedbackSimulator.inForeignContent &&
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html.hasUnescapedText(this.tokenizer.lastStartTagName, true)
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? text
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: escapeText(text));
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}
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/** Emits a serialized comment token into the output stream. */
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emitComment(token) {
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this.push(`<!--${token.text}-->`);
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}
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/** Emits a raw HTML string into the output stream. */
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emitRaw(html) {
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this.push(html);
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}
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}
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//# sourceMappingURL=index.js.map
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