59 lines
2.2 KiB
JavaScript
59 lines
2.2 KiB
JavaScript
// freeze Array#slice, just in case of funny business later.
|
|
var _slice = Array.prototype.slice;
|
|
var getPromise = require('./_promise.js');
|
|
|
|
// deferred gets its own scope to prevent inadvertent capture in the closure
|
|
var deferred = function(options) {
|
|
var Promise = getPromise();
|
|
var resolve, reject, p = new Promise(function(_resolve, _reject) {
|
|
resolve = _resolve; reject = _reject;
|
|
});
|
|
var pattern = (options && options.pattern);
|
|
var noError = (options && options.noError);
|
|
var cb = pattern ? function(err) {
|
|
if (err && !noError) { return reject(err); }
|
|
var result = {}, i, offset = noError ? 0 : 1;
|
|
for (i = 0; i < pattern.length; i++) {
|
|
result[pattern[i]] = arguments[i+offset];
|
|
}
|
|
resolve(result);
|
|
} : noError ? resolve : function(err, val) {
|
|
if (err) { reject(err); } else { resolve(val); }
|
|
};
|
|
return { promise: p, callback: cb };
|
|
};
|
|
var promisify = module.exports = function(context, func, mandatoryArgs, options) {
|
|
if (options && options.callbackIsFirstArg) {
|
|
// duplicate some code here so we don't have to process this unusual
|
|
// situation at runtime in the common case.
|
|
return function(cb) {
|
|
if (typeof(cb) === 'function') {
|
|
return func.apply(context, arguments);
|
|
}
|
|
var d = deferred(options);
|
|
var a = _slice.call(arguments, 0);
|
|
a.unshift(d.callback);
|
|
func.apply(context, a);
|
|
return d.promise;
|
|
};
|
|
}
|
|
return function() {
|
|
var cb = arguments[arguments.length - 1];
|
|
if (typeof(cb) === 'function') {
|
|
return func.apply(context, arguments);
|
|
}
|
|
// ooh, promises.
|
|
var d = deferred(options);
|
|
var a = _slice.call(arguments, 0);
|
|
while (a.length < mandatoryArgs) { a.push(undefined); }
|
|
a.push(d.callback);
|
|
var retval = func.apply(context, a);
|
|
if (options && options.returnsObject) {
|
|
// it would be nice to have a better convention here
|
|
Object.defineProperty(retval, 'promise', { value: d.promise });
|
|
return retval;
|
|
}
|
|
return d.promise;
|
|
};
|
|
};
|