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- var Promise = require('any-promise')
- var assert = require('assert')
- module.exports = thenify
- /**
- * Turn async functions into promises
- *
- * @param {Function} $$__fn__$$
- * @return {Function}
- * @api public
- */
- function thenify($$__fn__$$) {
- assert(typeof $$__fn__$$ === 'function')
- return eval(createWrapper($$__fn__$$.name.replace(/\s|bound(?!$)/g,'')))
- }
- /**
- * Turn async functions into promises and backward compatible with callback
- *
- * @param {Function} $$__fn__$$
- * @return {Function}
- * @api public
- */
- thenify.withCallback = function ($$__fn__$$) {
- assert(typeof $$__fn__$$ === 'function')
- return eval(createWrapper($$__fn__$$.name, true))
- }
- function createCallback(resolve, reject) {
- return function(err, value) {
- if (err) return reject(err)
- var length = arguments.length
- if (length <= 2) return resolve(value)
- var values = new Array(length - 1)
- for (var i = 1; i < length; ++i) values[i - 1] = arguments[i]
- resolve(values)
- }
- }
- function createWrapper(name, withCallback) {
- withCallback = withCallback ?
- 'var lastType = typeof arguments[len - 1]\n'
- + 'if (lastType === "function") return $$__fn__$$.apply(self, arguments)\n'
- : ''
- return '(function ' + (name || '') + '() {\n'
- + 'var self = this\n'
- + 'var len = arguments.length\n'
- + withCallback
- + 'var args = new Array(len + 1)\n'
- + 'for (var i = 0; i < len; ++i) args[i] = arguments[i]\n'
- + 'var lastIndex = i\n'
- + 'return new Promise(function (resolve, reject) {\n'
- + 'args[lastIndex] = createCallback(resolve, reject)\n'
- + '$$__fn__$$.apply(self, args)\n'
- + '})\n'
- + '})'
- }
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