nodekit-cli-lib/lib/nodekit-lib/util/promise-util.js

Command-line helpers for NodeKit command line interface

/**
    Licensed to OffGrid Networks (OGN) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  OGN licenses this file
    to you 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.
*/

var Q = require('q');

// Given a function and an array of values, creates a chain of promises that
// will sequentially execute func(args[i]).
// Returns a promise.
//
function Q_chainmap(args, func) {
    return Q.when().then(function(inValue) {
        return args.reduce(function(soFar, arg) {
            return soFar.then(function(val) {
                return func(arg, val);
            });
        }, Q(inValue));
    });
}

// Behaves similar to Q_chainmap but gracefully handles failures.
// When a promise in the chain is rejected, it will call the failureCallback and then continue the processing, instead of stopping
function Q_chainmap_graceful(args, func, failureCallback) {
    return Q.when().then(function(inValue) {
        return args.reduce(function(soFar, arg) {
            return soFar.then(function(val) {
                return func(arg, val);
            }).fail(function(err) {
                if (failureCallback) {
                    failureCallback(err);
                }
            });
        }, Q(inValue));
    });
}

exports.Q_chainmap = Q_chainmap;
exports.Q_chainmap_graceful = Q_chainmap_graceful;