dynatrace-cordova-outsystems-plugin/node_modules/pn/_promisify.js

This plugin gives you the ability to use the Dynatrace instrumentation in your hybrid application (Cordova, Ionic, ..). It uses the Mobile Agent, the JavaScript Agent and the Javascript Bridge. The Mobile Agent will give you all device specific values con

// freeze Array#slice, just in case of funny business later.
var _slice = Array.prototype.slice;
var getPromise = require('./_promise.js');

// deferred gets its own scope to prevent inadvertent capture in the closure
var deferred = function(options) {
    var Promise = getPromise();
    var resolve, reject, p = new Promise(function(_resolve, _reject) {
        resolve = _resolve; reject = _reject;
    });
    var pattern = (options && options.pattern);
    var noError = (options && options.noError);
    var cb = pattern ? function(err) {
        if (err && !noError) { return reject(err); }
        var result = {}, i, offset = noError ? 0 : 1;
        for (i = 0; i < pattern.length; i++) {
            result[pattern[i]] = arguments[i+offset];
        }
        resolve(result);
    } : noError ? resolve : function(err, val) {
        if (err) { reject(err); } else { resolve(val); }
    };
    return { promise: p, callback: cb };
};
var promisify = module.exports = function(context, func, mandatoryArgs, options) {
    if (options && options.callbackIsFirstArg) {
        // duplicate some code here so we don't have to process this unusual
        // situation at runtime in the common case.
        return function(cb) {
            if (typeof(cb) === 'function') {
                return func.apply(context, arguments);
            }
            var d = deferred(options);
            var a = _slice.call(arguments, 0);
            a.unshift(d.callback);
            func.apply(context, a);
            return d.promise;
        };
    }
    return function() {
        var cb = arguments[arguments.length - 1];
        if (typeof(cb) === 'function') {
            return func.apply(context, arguments);
        }
        // ooh, promises.
        var d = deferred(options);
        var a = _slice.call(arguments, 0);
        while (a.length < mandatoryArgs) { a.push(undefined); }
        a.push(d.callback);
        var retval = func.apply(context, a);
        if (options && options.returnsObject) {
            // it would be nice to have a better convention here
            Object.defineProperty(retval, 'promise', { value: d.promise });
            return retval;
        }
        return d.promise;
    };
};