81 lines
1.9 KiB
JavaScript
81 lines
1.9 KiB
JavaScript
'use strict'
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var Transform = require('stream').Transform
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var util = require('util')
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/**
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* @module stream-via
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*/
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module.exports = via
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via.async = viaAsync
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/**
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* @param {module:stream-via~throughFunction} - a function to process each chunk
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* @param [options] {object} - passed to the returned stream constructor
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* @return {external:Duplex}
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* @alias module:stream-via
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*/
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function via (throughFunction, options) {
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options = options || {}
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var stream = Transform(options)
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stream._transform = function (chunk, enc, done) {
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if (chunk) {
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try {
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this.push(throughFunction(chunk, enc))
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} catch (err) {
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stream.emit('error', err)
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}
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}
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done()
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}
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/* node 0.10 polyfil */
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if (!options.objectMode) {
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if (options.readableObjectMode) stream._readableState.objectMode = true
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if (options.writableObjectMode) stream._writableState.objectMode = true
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}
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return stream
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}
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/**
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* @param {module:stream-via~throughFunction} - a function to process each chunk
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* @param [options] {object} - passed to the returned stream constructor
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* @return {external:Duplex}
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* @alias module:stream-via.async
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*/
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function viaAsync (throughFunction, options) {
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var stream = Transform(options)
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stream._transform = function (chunk, enc, done) {
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if (chunk) {
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try {
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throughFunction(chunk, enc, function (err, returnValue) {
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if (err) {
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stream.emit('error', err)
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} else {
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stream.push(returnValue)
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}
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done()
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})
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} catch (err) {
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stream.emit('error', err)
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done()
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}
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}
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}
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return stream
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}
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/**
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* @external Duplex
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* @see https://nodejs.org/api/stream.html#stream_class_stream_duplex
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*/
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/**
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* @typedef throughFunction
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* @type function
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* @param chunk {buffer|string}
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* @param enc {string}
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* @param done {function} - only used in `via.async`, call it like so: `done(err, returnValue)`.
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*/
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