packages/oo7/src/reactivePromise.js

// (C) Copyright 2016-2017 Parity Technologies (UK) Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//         http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

const ReactiveBond = require('./reactiveBond');

// Exactly like ReactiveBond, except only calls `execute` once. Further changes
// to members of `args` or `dependencies` have no effect.
class ReactivePromise extends ReactiveBond {
	constructor (
		args,
		dependencies,
		execute = args => this.changed(args),
		mayBeNull = true,
		resolveDepth = 1,
		cache = { id: null, stringify: JSON.stringify, parse: JSON.parse }
	) {
		var done = false;
		super(args, dependencies, resolvedArguments => {
			if (!done) {
				done = true;
				execute.bind(this)(resolvedArguments);
			}
		}, mayBeNull, resolveDepth, cache);
	}
}

module.exports = ReactivePromise;