hexo/node_modules/any-promise/register.js

95 lines
2.9 KiB
JavaScript

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