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