123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181 |
- 'use strict'
- const check = require('check-types')
- const events = require('./events')
- const promise = require('./promise')
- const walk = require('./walk')
- module.exports = parse
- const NDJSON_STATE = new Map()
- /**
- * Public function `parse`.
- *
- * Returns a promise and asynchronously parses a stream of JSON data. If
- * there are no errors, the promise is resolved with the parsed data. If
- * errors occur, the promise is rejected with the first error.
- *
- * @param stream: Readable instance representing the incoming JSON.
- *
- * @option reviver: Transformation function, invoked depth-first.
- *
- * @option yieldRate: The number of data items to process per timeslice,
- * default is 16384.
- *
- * @option Promise: The promise constructor to use, defaults to bluebird.
- *
- * @option ndjson: Set this to true to parse newline-delimited JSON. In
- * this case, each call will be resolved with one value
- * from the stream. To parse the entire stream, calls
- * should be made sequentially one-at-a-time until the
- * returned promise resolves to `undefined`.
- **/
- function parse (stream, options = {}) {
- const Promise = promise(options)
- try {
- check.assert.maybe.function(options.reviver, 'Invalid reviver option')
- } catch (err) {
- return Promise.reject(err)
- }
- const errors = []
- const scopes = []
- const reviver = options.reviver
- const shouldHandleNdjson = !! options.ndjson
- let emitter, resolve, reject, scopeKey
- if (shouldHandleNdjson && NDJSON_STATE.has(stream)) {
- const state = NDJSON_STATE.get(stream)
- NDJSON_STATE.delete(stream)
- emitter = state.emitter
- setImmediate(state.resume)
- } else {
- emitter = walk(stream, options)
- }
- emitter.on(events.array, array)
- emitter.on(events.object, object)
- emitter.on(events.property, property)
- emitter.on(events.string, value)
- emitter.on(events.number, value)
- emitter.on(events.literal, value)
- emitter.on(events.endArray, endScope)
- emitter.on(events.endObject, endScope)
- emitter.on(events.end, end)
- emitter.on(events.error, error)
- emitter.on(events.dataError, error)
- if (shouldHandleNdjson) {
- emitter.on(events.endLine, endLine)
- }
- return new Promise((res, rej) => {
- resolve = res
- reject = rej
- })
- function array () {
- if (errors.length > 0) {
- return
- }
- beginScope([])
- }
- function beginScope (parsed) {
- if (errors.length > 0) {
- return
- }
- if (scopes.length > 0) {
- value(parsed)
- }
- scopes.push(parsed)
- }
- function value (v) {
- if (errors.length > 0) {
- return
- }
- if (scopes.length === 0) {
- return scopes.push(v)
- }
- const scope = scopes[scopes.length - 1]
- if (scopeKey) {
- scope[scopeKey] = v
- scopeKey = null
- } else {
- scope.push(v)
- }
- }
- function object () {
- if (errors.length > 0) {
- return
- }
- beginScope({})
- }
- function property (name) {
- if (errors.length > 0) {
- return
- }
- scopeKey = name
- }
- function endScope () {
- if (errors.length > 0) {
- return
- }
- if (scopes.length > 1) {
- scopes.pop()
- }
- }
- function end () {
- if (shouldHandleNdjson) {
- const resume = emitter.pause()
- emitter.removeAllListeners()
- NDJSON_STATE.set(stream, { emitter, resume })
- }
- if (errors.length > 0) {
- return reject(errors[0])
- }
- if (reviver) {
- scopes[0] = transform(scopes[0], '')
- }
- resolve(scopes[0])
- }
- function transform (obj, key) {
- if (obj && typeof obj === 'object') {
- Object.keys(obj).forEach(childKey => {
- obj[childKey] = transform(obj[childKey], childKey)
- })
- }
- return reviver(key, obj)
- }
- function error (e) {
- errors.push(e)
- }
- function endLine () {
- if (scopes.length > 0) {
- end()
- }
- }
- }
|