"use strict"
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module.exports = require('./loader')(global, loadImplementation);
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/**
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* Node.js version of loadImplementation.
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*
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* Requires the given implementation and returns the registration
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* containing {Promise, implementation}
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*
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* If implementation is undefined or global.Promise, loads it
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* Otherwise uses require
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*/
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function loadImplementation(implementation){
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var impl = null
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if(shouldPreferGlobalPromise(implementation)){
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// if no implementation or env specified use global.Promise
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impl = {
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Promise: global.Promise,
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implementation: 'global.Promise'
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}
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} else if(implementation){
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// if implementation specified, require it
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var lib = require(implementation)
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impl = {
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Promise: lib.Promise || lib,
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implementation: implementation
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}
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} else {
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// try to auto detect implementation. This is non-deterministic
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// and should prefer other branches, but this is our last chance
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// to load something without throwing error
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impl = tryAutoDetect()
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}
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if(impl === null){
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throw new Error('Cannot find any-promise implementation nor'+
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' global.Promise. You must install polyfill or call'+
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' require("any-promise/register") with your preferred'+
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' implementation, e.g. require("any-promise/register/bluebird")'+
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' on application load prior to any require("any-promise").')
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}
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return impl
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}
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/**
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* Determines if the global.Promise should be preferred if an implementation
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* has not been registered.
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*/
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function shouldPreferGlobalPromise(implementation){
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if(implementation){
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return implementation === 'global.Promise'
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} else if(typeof global.Promise !== 'undefined'){
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// Load global promise if implementation not specified
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// Versions < 0.11 did not have global Promise
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// Do not use for version < 0.12 as version 0.11 contained buggy versions
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var version = (/v(\d+)\.(\d+)\.(\d+)/).exec(process.version)
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return !(version && +version[1] == 0 && +version[2] < 12)
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}
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// do not have global.Promise or another implementation was specified
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return false
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}
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/**
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* Look for common libs as last resort there is no guarantee that
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* this will return a desired implementation or even be deterministic.
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* The priority is also nearly arbitrary. We are only doing this
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* for older versions of Node.js <0.12 that do not have a reasonable
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* global.Promise implementation and we the user has not registered
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* the preference. This preserves the behavior of any-promise <= 0.1
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* and may be deprecated or removed in the future
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*/
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function tryAutoDetect(){
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var libs = [
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"es6-promise",
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"promise",
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"native-promise-only",
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"bluebird",
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"rsvp",
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"when",
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"q",
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"pinkie",
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"lie",
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"vow"]
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var i = 0, len = libs.length
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for(; i < len; i++){
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try {
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return loadImplementation(libs[i])
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} catch(e){}
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}
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return null
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}
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