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index.js
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index.js
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'use strict'
// pickup - transform RSS or Atom XML to JSON
exports = module.exports = Pickup
const attribute = require('./lib/attribute')
const mappings = require('./lib/mappings')
const os = require('os')
const sax = require('saxes')
const { Entry, Feed } = require('./lib/items')
const { StringDecoder } = require('string_decoder')
const { Transform } = require('readable-stream')
const { debuglog, inherits } = require('util')
const debug = debuglog('pickup')
function State (entry, feed, image, map, name, precedence) {
this.entry = entry
this.feed = feed
this.image = image
this.map = map
this.name = name
this.precedence = precedence
}
State.prototype.setName = function (name) {
this.map = mappings[name] || this.map
this.name = name
}
State.prototype.key = function () {
return this.map.get(this.name)
}
State.prototype.takesPrecedence = function () {
return this.precedence.has(this.name)
}
function OpenHandlers (t) {
this.channel = t.feedopen
this.feed = t.feedopen
this.item = t.entryopen
this.entry = t.entryopen
this.image = t.imageopen
}
function CloseHandlers (t) {
this.channel = t.feedclose
this.feed = t.feedclose
this.item = t.entryclose
this.entry = t.entryclose
this.image = t.imageclose
}
function encodingFromString (str) {
if (str.match(/utf-8/i)) {
return 'utf8'
} else if (str.match(/iso-8859-1/i)) {
return 'binary'
}
return 'utf8'
}
function encodingFromOpts (opts) {
const str = opts ? opts.charset : null
if (typeof str !== 'string') return null
return encodingFromString(str)
}
function Pickup (opts) {
if (!(this instanceof Pickup)) return new Pickup(opts)
Transform.call(this, opts)
if (!Pickup.openHandlers) {
Pickup.openHandlers = new OpenHandlers(Pickup.prototype)
Pickup.closeHandlers = new CloseHandlers(Pickup.prototype)
}
this.encoding = encodingFromOpts(opts)
this.decoder = new StringDecoder(this.encoding)
this.eventMode = opts && opts.eventMode
this.state = new State(
null,
null,
false,
new Map(),
'',
new Set(['content:encoded', 'pubDate'])
)
const parser = new sax.SaxesParser(opts ? opts.parser : null)
parser.ontext = (text) => {
const t = text.trim()
if (t.length === 0) {
debug('discarding text: whitespace')
return
}
const state = this.state
const current = state.entry || state.feed
if (!current || !state.map) return
let key = state.key()
if (key === undefined) return
if (state.image && state.name === 'url') key = 'image'
const isSet = current[key] !== undefined
if (isSet) {
if (!state.takesPrecedence()) {
return
} else if (state.name === 'content:encoded' && t.length > 4096) {
debug('%s: discarding text: too long', state.name)
return
}
debug('%s: taking precedence: ( %s, %s )', state.name, key, t)
}
current[key] = t
}
// Not differentiating between cdata and text, whichever comes first wins.
// This might be a mistake, but I don’t see a clear-cut alternative.
parser.oncdata = parser.ontext
parser.onerror = (er) => {
debug('error: %s', er)
this.emit('error', er)
}
const handle = (name, handlers) => {
if (Object.prototype.hasOwnProperty.call(handlers, name)) {
handlers[name].apply(this)
}
}
parser.onopentag = (node) => {
this.state.setName(node.name)
handle(node.name, Pickup.openHandlers)
const current = this.state.entry || this.state.feed
if (current) {
const key = this.state.key(node.name)
if (key) {
const keys = Object.keys(node.attributes)
if (keys.length) {
const kv = attribute(key, node.attributes, current)
if (kv) {
current[kv[0]] = kv[1]
}
}
}
}
}
parser.onclosetag = (node) => {
handle(node.name, Pickup.closeHandlers)
this.state.setName()
}
this.parser = parser
}
inherits(Pickup, Transform)
Pickup.prototype.objectMode = function () {
return this._readableState.objectMode
}
Pickup.prototype.feedopen = function () {
this.state.feed = new Feed()
}
Pickup.prototype.entryopen = function () {
this.state.entry = new Entry()
}
Pickup.prototype.imageopen = function () {
this.state.image = true
}
Pickup.prototype.entryclose = function () {
const entry = this.state.entry
if (!entry) return
if (!this.eventMode) {
if (this.objectMode()) {
this.push(entry)
} else {
this.push(JSON.stringify(entry) + os.EOL)
}
} else {
this.emit('entry', entry)
}
this.state.entry = null
}
Pickup.prototype.feedclose = function () {
const feed = this.state.feed
if (!feed) return
if (!this.eventMode) {
if (this.objectMode()) {
this.push(feed)
} else {
this.push(JSON.stringify(feed) + os.EOL)
}
} else {
this.emit('feed', feed)
}
this.state.feed = null
}
Pickup.prototype.imageclose = function () {
this.state.image = false
}
function free (parser) {
parser.oncdata = null
parser.onclosetag = null
parser.onerror = null
parser.onopentag = null
parser.onready = null
parser.ontext = null
}
Pickup.prototype.invalidate = function () {
debug('invalidating')
this.parser.close()
free(this.parser)
this._decoder = null
this.encoding = null
this.parser = null
this.state = null
}
Pickup.prototype._destroy = function (er, cb) {
this.invalidate()
Transform.prototype._destroy.call(this, er, cb)
}
Pickup.prototype._final = function (cb) {
this.invalidate()
cb()
}
function cribEncoding (str) {
const enc = str.split('encoding')[1]
const def = 'utf8'
if (!enc) return def
if (enc.trim()[0] === '=') {
return encodingFromString(enc)
}
return def
}
Pickup.prototype._transform = function (chunk, enc, cb) {
if (!this._decoder) {
if (!this.encoding) {
// This, of course, fails--yielding 'utf8'--if the first chunk is too
// short to contain the encoding tag.
const t = chunk.toString('ascii', 0, 128)
this.encoding = cribEncoding(t)
}
this.emit('encoding', this.encoding)
}
const str = this.decoder.write(chunk)
if (this.parser.closed) {
this.parser.onready = () => {
this.parser.write(str)
cb()
}
return
}
this.parser.write(str)
cb()
}
// Exports
exports.Pickup = Pickup
exports.Feed = Feed
exports.Entry = Entry
// Extending surface area when testing.
if (process.mainModule && process.mainModule.filename.match(/test/) !== null) {
exports.extend = function (origin, add) {
return Object.assign(origin, add || Object.create(null))
}
exports.entry = function (obj) {
return exports.extend(new Entry(), obj)
}
exports.feed = function (obj) {
return exports.extend(new Feed(), obj)
}
exports.cribEncoding = cribEncoding
exports.EVENTS = [
'data',
'drain',
'readable',
'end',
'entry',
'error',
'feed',
'finish'
]
}