registry.js

/*
 * Copyright 2012-2016 the original author or authors
 * @license MIT, see LICENSE.txt for details
 *
 * @author Scott Andrews
 */

'use strict';

var mime, registry;

mime = require('../mime');

function Registry(mimes) {

	/**
	 * Lookup the converter for a MIME type
	 *
	 * @param {string} type the MIME type
	 * @return a promise for the converter
	 */
	this.lookup = function lookup(type) {
		var parsed;

		parsed = typeof type === 'string' ? mime.parse(type) : type;

		if (mimes[parsed.raw]) {
			return mimes[parsed.raw];
		}
		if (mimes[parsed.type + parsed.suffix]) {
			return mimes[parsed.type + parsed.suffix];
		}
		if (mimes[parsed.type]) {
			return mimes[parsed.type];
		}
		if (mimes[parsed.suffix]) {
			return mimes[parsed.suffix];
		}

		return Promise.reject(new Error('Unable to locate converter for mime "' + parsed.raw + '"'));
	};

	/**
	 * Create a late dispatched proxy to the target converter.
	 *
	 * Common when a converter is registered under multiple names and
	 * should be kept in sync if updated.
	 *
	 * @param {string} type mime converter to dispatch to
	 * @returns converter whose read/write methods target the desired mime converter
	 */
	this.delegate = function delegate(type) {
		return {
			read: function () {
				var args = arguments;
				return this.lookup(type).then(function (converter) {
					return converter.read.apply(this, args);
				}.bind(this));
			}.bind(this),
			write: function () {
				var args = arguments;
				return this.lookup(type).then(function (converter) {
					return converter.write.apply(this, args);
				}.bind(this));
			}.bind(this)
		};
	};

	/**
	 * Register a custom converter for a MIME type
	 *
	 * @param {string} type the MIME type
	 * @param converter the converter for the MIME type
	 * @return a promise for the converter
	 */
	this.register = function register(type, converter) {
		mimes[type] = Promise.resolve(converter);
		return mimes[type];
	};

	/**
	 * Create a child registry whoes registered converters remain local, while
	 * able to lookup converters from its parent.
	 *
	 * @returns child MIME registry
	 */
	this.child = function child() {
		return new Registry(Object.create(mimes));
	};

}

registry = new Registry({});

// include provided serializers
registry.register('application/hal', require('./type/application/hal'));
registry.register('application/json', require('./type/application/json'));
registry.register('application/x-www-form-urlencoded', require('./type/application/x-www-form-urlencoded'));
registry.register('multipart/form-data', require('./type/multipart/form-data'));
registry.register('text/plain', require('./type/text/plain'));

registry.register('+json', registry.delegate('application/json'));

module.exports = registry;