126 lines
2.1 KiB
JavaScript
126 lines
2.1 KiB
JavaScript
/**
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* Module Dependencies
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*/
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var noop = function(){};
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var co = require('co');
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/**
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* Export `wrap-fn`
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*/
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module.exports = wrap;
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/**
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* Wrap a function to support
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* sync, async, and gen functions.
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*
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* @param {Function} fn
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* @param {Function} done
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* @return {Function}
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* @api public
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*/
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function wrap(fn, done) {
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done = once(done || noop);
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return function() {
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// prevents arguments leakage
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// see https://github.com/petkaantonov/bluebird/wiki/Optimization-killers#3-managing-arguments
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var i = arguments.length;
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var args = new Array(i);
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while (i--) args[i] = arguments[i];
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var ctx = this;
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// done
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if (!fn) {
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return done.apply(ctx, [null].concat(args));
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}
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// async
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if (fn.length > args.length) {
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// NOTE: this only handles uncaught synchronous errors
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try {
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return fn.apply(ctx, args.concat(done));
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} catch (e) {
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return done(e);
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}
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}
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// generator
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if (generator(fn)) {
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return co(fn).apply(ctx, args.concat(done));
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}
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// sync
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return sync(fn, done).apply(ctx, args);
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}
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}
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/**
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* Wrap a synchronous function execution.
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*
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* @param {Function} fn
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* @param {Function} done
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* @return {Function}
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* @api private
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*/
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function sync(fn, done) {
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return function () {
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var ret;
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try {
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ret = fn.apply(this, arguments);
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} catch (err) {
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return done(err);
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}
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if (promise(ret)) {
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ret.then(function (value) { done(null, value); }, done);
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} else {
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ret instanceof Error ? done(ret) : done(null, ret);
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}
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}
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}
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/**
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* Is `value` a generator?
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*
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* @param {Mixed} value
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* @return {Boolean}
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* @api private
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*/
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function generator(value) {
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return value
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&& value.constructor
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&& 'GeneratorFunction' == value.constructor.name;
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}
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/**
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* Is `value` a promise?
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*
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* @param {Mixed} value
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* @return {Boolean}
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* @api private
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*/
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function promise(value) {
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return value && 'function' == typeof value.then;
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}
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/**
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* Once
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*/
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function once(fn) {
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return function() {
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var ret = fn.apply(this, arguments);
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fn = noop;
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return ret;
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};
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}
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