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"use strict";
/* global module, require */
module.exports = function () {
"use strict";
// Get a promise object. This may be native, or it may be polyfilled
var ES6Promise = require("./promise.js");
/**
* thatLooksLikeAPromiseToMe()
*
* Duck-types a promise.
*
* @param {object} o
* @return {bool} True if this resembles a promise
*/
function thatLooksLikeAPromiseToMe(o) {
return o && typeof o.then === "function" && typeof o.catch === "function";
}
/**
* promisify()
*
* Transforms callback-based function -- func(arg1, arg2 .. argN, callback) -- into
* an ES6-compatible Promise. Promisify provides a default callback of the form (error, result)
* and rejects when `error` is truthy. You can also supply settings object as the second argument.
*
* @param {function} original - The function to promisify
* @param {object} settings - Settings object
* @param {object} settings.thisArg - A `this` context to use. If not set, assume `settings` _is_ `thisArg`
* @param {bool} settings.multiArgs - Should multiple arguments be returned as an array?
* @return {function} A promisified version of `original`
*/
return function promisify(original, settings) {
return function () {
for (var _len = arguments.length, args = Array(_len), _key = 0; _key < _len; _key++) {
args[_key] = arguments[_key];
}
var returnMultipleArguments = settings && settings.multiArgs;
var target = void 0;
if (settings && settings.thisArg) {
target = settings.thisArg;
} else if (settings) {
target = settings;
}
// Return the promisified function
return new ES6Promise(function (resolve, reject) {
// Append the callback bound to the context
args.push(function callback(err) {
if (err) {
return reject(err);
}
for (var _len2 = arguments.length, values = Array(_len2 > 1 ? _len2 - 1 : 0), _key2 = 1; _key2 < _len2; _key2++) {
values[_key2 - 1] = arguments[_key2];
}
if (false === !!returnMultipleArguments) {
return resolve(values[0]);
}
resolve(values);
});
// Call the function
var response = original.apply(target, args);
// If it looks like original already returns a promise,
// then just resolve with that promise. Hopefully, the callback function we added will just be ignored.
if (thatLooksLikeAPromiseToMe(response)) {
resolve(response);
}
});
};
};
}();
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