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Wrapping a callback-based function into an ES6 Generator (requires node 0.11+)
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var q = require('q') | |
function generatorify(fn, context) { | |
return function() { | |
var deferred = q.defer(), | |
callback = makeCallback(deferred), | |
args = Array.prototype.slice.call(arguments).concat(callback); | |
fn.apply(context, args); | |
return deferred.promise; | |
}; | |
} | |
function makeCallback(deferred) { | |
return function (err) { | |
if (err) { | |
deferred.reject(err); | |
} else if (arguments.length < 2) { | |
deferred.resolve(); | |
} else if (arguments.length === 2) { | |
deferred.resolve(arguments[1]); | |
} else { | |
deferred.resolve(Array.prototype.slice.call(arguments, 1)); | |
} | |
}; | |
} | |
// This is monkey patching so don't do it lightly | |
Function.prototype.generator = function (context) { | |
return generatorify(this, context); | |
}; | |
/// Usage | |
function callbackBasedFunction(arg, callback) { | |
callback(null, arg + 1); | |
} | |
function *generator() { | |
var genFunction = generatorify(callbackBasedFunction); | |
result = yield genFunction(2); | |
assert result == 3; | |
// or with monkey patching | |
result = yield callbackBasedFunction.generator(null)(2) | |
} |
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