119 lines
4.2 KiB
JavaScript
119 lines
4.2 KiB
JavaScript
// Forked from https://github.com/jahewson/node-byline
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// Copyright (C) 2011-2015 John Hewson
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to
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// deal in the Software without restriction, including without limitation the
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// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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// sell copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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// IN THE SOFTWARE.
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/**
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* @module byline
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* @private
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*/
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const stream = require('stream')
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const timers = require('timers')
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const { Buffer } = require('buffer')
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const createLineStream = (readStream, options) => {
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if (!readStream) throw new Error('expected readStream')
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if (!readStream.readable) throw new Error('readStream must be readable')
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const ls = new LineStream(options)
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readStream.pipe(ls)
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return ls
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}
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/**
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* Fork from {@link https://github.com/jahewson/node-byline}.
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* @see https://github.com/jahewson/node-byline
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* @alias module:byline.LineStream
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* @private
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*/
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class LineStream extends stream.Transform {
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constructor (options) {
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super(options)
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options = options || {}
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// use objectMode to stop the output from being buffered
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// which re-concatanates the lines, just without newlines.
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this._readableState.objectMode = true
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this._lineBuffer = []
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this._keepEmptyLines = options.keepEmptyLines || false
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this._lastChunkEndedWithCR = false
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// take the source's encoding if we don't have one
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this.once('pipe', src => {
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if (!this.encoding && src instanceof stream.Readable) this.encoding = src._readableState.encoding // but we can't do this for old-style streams
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})
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}
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_transform (chunk, encoding, done) {
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// decode binary chunks as UTF-8
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encoding = encoding || 'utf8'
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if (Buffer.isBuffer(chunk)) {
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if (encoding === 'buffer') {
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chunk = chunk.toString() // utf8
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encoding = 'utf8'
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} else chunk = chunk.toString(encoding)
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}
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this._chunkEncoding = encoding
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// see: http://www.unicode.org/reports/tr18/#Line_Boundaries
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const lines = chunk.split(/\r\n|[\n\v\f\r\x85\u2028\u2029]/g)
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// don't split CRLF which spans chunks
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if (this._lastChunkEndedWithCR && chunk[0] === '\n') lines.shift()
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if (this._lineBuffer.length > 0) {
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this._lineBuffer[this._lineBuffer.length - 1] += lines[0]
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lines.shift()
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}
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this._lastChunkEndedWithCR = chunk[chunk.length - 1] === '\r'
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this._lineBuffer = this._lineBuffer.concat(lines)
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this._pushBuffer(encoding, 1, done)
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}
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_pushBuffer (encoding, keep, done) {
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// always buffer the last (possibly partial) line
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while (this._lineBuffer.length > keep) {
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const line = this._lineBuffer.shift()
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// skip empty lines
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if (this._keepEmptyLines || line.length > 0) {
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if (!this.push(this._reencode(line, encoding))) {
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// when the high-water mark is reached, defer pushes until the next tick
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timers.setImmediate(() => { this._pushBuffer(encoding, keep, done) })
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return
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}
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}
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}
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done()
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}
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_flush (done) {
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this._pushBuffer(this._chunkEncoding, 0, done)
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}
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// see Readable::push
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_reencode (line, chunkEncoding) {
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if (this.encoding && this.encoding !== chunkEncoding) return Buffer.from(line, chunkEncoding).toString(this.encoding)
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else if (this.encoding) return line // this should be the most common case, i.e. we're using an encoded source stream
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else return Buffer.from(line, chunkEncoding)
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}
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}
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module.exports = createLineStream
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