228 lines
5.9 KiB
JavaScript
228 lines
5.9 KiB
JavaScript
// put javascript in here
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'use strict'
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const Parser = require('jsonparse')
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const Minipass = require('minipass')
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class JSONStreamError extends Error {
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constructor (err, caller) {
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super(err.message)
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Error.captureStackTrace(this, caller || this.constructor)
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}
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get name () {
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return 'JSONStreamError'
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}
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set name (n) {}
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}
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const check = (x, y) =>
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typeof x === 'string' ? String(y) === x
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: x && typeof x.test === 'function' ? x.test(y)
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: typeof x === 'boolean' || typeof x === 'object' ? x
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: typeof x === 'function' ? x(y)
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: false
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const _parser = Symbol('_parser')
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const _onValue = Symbol('_onValue')
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const _onTokenOriginal = Symbol('_onTokenOriginal')
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const _onToken = Symbol('_onToken')
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const _onError = Symbol('_onError')
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const _count = Symbol('_count')
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const _path = Symbol('_path')
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const _map = Symbol('_map')
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const _root = Symbol('_root')
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const _header = Symbol('_header')
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const _footer = Symbol('_footer')
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const _setHeaderFooter = Symbol('_setHeaderFooter')
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const _ending = Symbol('_ending')
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class JSONStream extends Minipass {
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constructor (opts = {}) {
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super({
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...opts,
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objectMode: true,
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})
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this[_ending] = false
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const parser = this[_parser] = new Parser()
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parser.onValue = value => this[_onValue](value)
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this[_onTokenOriginal] = parser.onToken
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parser.onToken = (token, value) => this[_onToken](token, value)
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parser.onError = er => this[_onError](er)
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this[_count] = 0
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this[_path] = typeof opts.path === 'string'
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? opts.path.split('.').map(e =>
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e === '$*' ? { emitKey: true }
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: e === '*' ? true
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: e === '' ? { recurse: true }
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: e)
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: Array.isArray(opts.path) && opts.path.length ? opts.path
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: null
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this[_map] = typeof opts.map === 'function' ? opts.map : null
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this[_root] = null
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this[_header] = null
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this[_footer] = null
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this[_count] = 0
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}
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[_setHeaderFooter] (key, value) {
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// header has not been emitted yet
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if (this[_header] !== false) {
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this[_header] = this[_header] || {}
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this[_header][key] = value
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}
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// footer has not been emitted yet but header has
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if (this[_footer] !== false && this[_header] === false) {
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this[_footer] = this[_footer] || {}
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this[_footer][key] = value
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}
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}
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[_onError] (er) {
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// error will always happen during a write() call.
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const caller = this[_ending] ? this.end : this.write
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this[_ending] = false
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return this.emit('error', new JSONStreamError(er, caller))
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}
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[_onToken] (token, value) {
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const parser = this[_parser]
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this[_onTokenOriginal].call(parser, token, value)
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if (parser.stack.length === 0) {
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if (this[_root]) {
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const root = this[_root]
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if (!this[_path])
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super.write(root)
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this[_root] = null
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this[_count] = 0
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}
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}
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}
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[_onValue] (value) {
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const parser = this[_parser]
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// the LAST onValue encountered is the root object.
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// just overwrite it each time.
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this[_root] = value
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if(!this[_path]) return
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let i = 0 // iterates on path
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let j = 0 // iterates on stack
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let emitKey = false
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let emitPath = false
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while (i < this[_path].length) {
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const key = this[_path][i]
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j++
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if (key && !key.recurse) {
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const c = (j === parser.stack.length) ? parser : parser.stack[j]
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if (!c) return
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if (!check(key, c.key)) {
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this[_setHeaderFooter](c.key, value)
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return
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}
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emitKey = !!key.emitKey;
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emitPath = !!key.emitPath;
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i++
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} else {
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i++
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if (i >= this[_path].length)
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return
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const nextKey = this[_path][i]
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if (!nextKey)
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return
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while (true) {
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const c = (j === parser.stack.length) ? parser : parser.stack[j]
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if (!c) return
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if (check(nextKey, c.key)) {
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i++
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if (!Object.isFrozen(parser.stack[j]))
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parser.stack[j].value = null
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break
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} else {
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this[_setHeaderFooter](c.key, value)
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}
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j++
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}
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}
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}
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// emit header
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if (this[_header]) {
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const header = this[_header]
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this[_header] = false
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this.emit('header', header)
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}
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if (j !== parser.stack.length) return
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this[_count] ++
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const actualPath = parser.stack.slice(1)
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.map(e => e.key).concat([parser.key])
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if (value !== null && value !== undefined) {
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const data = this[_map] ? this[_map](value, actualPath) : value
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if (data !== null && data !== undefined) {
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const emit = emitKey || emitPath ? { value: data } : data
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if (emitKey)
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emit.key = parser.key
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if (emitPath)
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emit.path = actualPath
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super.write(emit)
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}
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}
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if (parser.value)
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delete parser.value[parser.key]
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for (const k of parser.stack) {
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k.value = null
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}
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}
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write (chunk, encoding, cb) {
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if (typeof encoding === 'function')
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cb = encoding, encoding = null
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if (typeof chunk === 'string')
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chunk = Buffer.from(chunk, encoding)
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else if (!Buffer.isBuffer(chunk))
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return this.emit('error', new TypeError(
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'Can only parse JSON from string or buffer input'))
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this[_parser].write(chunk)
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if (cb)
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cb()
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return this.flowing
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}
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end (chunk, encoding, cb) {
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this[_ending] = true
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if (typeof encoding === 'function')
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cb = encoding, encoding = null
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if (typeof chunk === 'function')
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cb = chunk, chunk = null
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if (chunk)
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this.write(chunk, encoding)
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if (cb)
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this.once('end', cb)
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const h = this[_header]
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this[_header] = null
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const f = this[_footer]
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this[_footer] = null
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if (h)
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this.emit('header', h)
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if (f)
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this.emit('footer', f)
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return super.end()
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}
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static get JSONStreamError () { return JSONStreamError }
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static parse (path, map) {
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return new JSONStream({path, map})
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}
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}
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module.exports = JSONStream
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