Convert to Stream object and allow options to be passed in

[willfarrell]

BREAKING CHANGE
Closes #16

• Stream part by @cjblomqvist
• See README for options
• See example for piping out json (examples/json.js)

[Amantel]

Should not this be merged?

[Amantel]

Hm, sorry, but should not it be possible to pipe this to the next stage?
like input.pipe(parse).pipe(fs.writeStream('xxx'))

[hubgit]

It does seem that piping the output stream to a file creates corrupted output, for some reason.

[jobe451]

I inluded this pull request into one of my projects and it seems to perform just fine.

This example seems rather to be wrong. Obviously you can't pipe json to a stream-writer that expects to get string or buffer to be streamed to.

input.pipe(parse).pipe(fs.writeStream('xxx'))

Working example (extended from the example coming in this pull request)

const stream  = require('stream');
const fs = require('fs');
const xmlStream = require('../');

class ConsoleLogStream extends stream.Writable {
  _write(chunk, enc, next) {
  	console.log(chunk);
    next();
  }
}

const input = fs.createReadStream('json.xml');
const parse = new xmlStream({
  element: 'media',
  attributes: false,
  output:'json',
  preserve: {},
  collect:['id']
});
const logStream = new ConsoleLogStream();

input.pipe(parse).pipe(logStream);

[xShirase]

Yeah, that works and should be merged IMO

[jobe451]

There is one issue I discovered with this pull-request. Once a file is streamed, the "finish" event is not triggered a the end of the pipe. Also if I inhearit from this class, _final won't be triggered. I assume that this is caused because those class inherit from the base class stream.Stream and not from Readable and Writeable. I will do my own implementation in Typescript by wrapping it somehow...

[jobe451]

I removed xml-stream and am using now directly node-expat. Turns out also node-expat does not emit an "end" event, which probably is the root cause here.

So this my core typescript calls now:

import stream = require("stream");
import expat = require("node-expat");

export class XmlParser extends stream.Transform {
	private parser: expat.Parser;
	private parsingLevel = 0;

	constructor (config: any) {
		super({objectMode: true});

		this.parser  = new expat.Parser('UTF-8')

		this.parser.on('startElement', (name, attrs) => {
			this.parsingLevel++;
		});

		this.parser.on("error", (error) => {
			this.emit("error", error);
		});

		this.parser.on('endElement', (text) => {
			this.parsingLevel--;
			if(this.parsingLevel === 0) {
				this.emit("end");
			}
		});
	}

	_transform(chunk, encoding, callback) {
		this.parser.write(chunk, encoding, callback);
	}
}