thenables.js

"use strict";
module.exports = function(Promise, INTERNAL) {
var util = require("./util");
var errorObj = util.errorObj;
var isObject = util.isObject;

function tryConvertToPromise(obj, context) {
    if (isObject(obj)) {
        if (obj instanceof Promise) return obj;
        var then = getThen(obj);
        if (then === errorObj) {
            if (context) context._pushContext();
            var ret = Promise.reject(then.e);
            if (context) context._popContext();
            return ret;
        } else if (typeof then === "function") {
            if (isAnyBluebirdPromise(obj)) {
                var ret = new Promise(INTERNAL);
                obj._then(
                    ret._fulfill,
                    ret._reject,
                    undefined,
                    ret,
                    null
                );
                return ret;
            }
            return doThenable(obj, then, context);
        }
    }
    return obj;
}

function doGetThen(obj) {
    return obj.then;
}

function getThen(obj) {
    try {
        return doGetThen(obj);
    } catch (e) {
        errorObj.e = e;
        return errorObj;
    }
}

var hasProp = {}.hasOwnProperty;
function isAnyBluebirdPromise(obj) {
    try {
        return hasProp.call(obj, "_promise0");
    } catch (e) {
        return false;
    }
}

function doThenable(x, then, context) {
    var promise = new Promise(INTERNAL);
    var ret = promise;
    if (context) context._pushContext();
    promise._captureStackTrace();
    if (context) context._popContext();
    var synchronous = true;
    var result = util.tryCatch(then).call(x, resolve, reject);
    synchronous = false;

    if (promise && result === errorObj) {
        promise._rejectCallback(result.e, true, true);
        promise = null;
    }

    function resolve(value) {
        if (!promise) return;
        promise._resolveCallback(value);
        promise = null;
    }

    function reject(reason) {
        if (!promise) return;
        promise._rejectCallback(reason, synchronous, true);
        promise = null;
    }
    return ret;
}

return tryConvertToPromise;
};