export default function createGroup(definition) {
let streamsDefs = ('function' === typeof definition) ?
definition() :
definition;
if(('object' !== typeof streamsDefs) ||
(streamsDefs === null) ||
Array.isArray(streamsDefs)
) {
throw new TypeError('Cycle Streams Group must be an object.');
}
if (this instanceof createGroup) { // jshint ignore:line
throw new Error('Cannot use `new` operator on `createStreamsGroup()`, it is not a constructor.');
}
let streamsWithDeps = mapValues(streamsDefs, (streamFn) => ({
dependencies: getParametersNames(streamFn)
.map(_removeUnderscores),
stream: createStream(streamFn)
}));
let group = mapValues(streamsWithDeps, ({ stream }) => stream);
// add `inject` and `dispose` as not enumerable properties to make them
// not visible for `each` function
Object.defineProperty(group, 'inject', {
enumerable: false,
value: _makeInjectFn(streamsWithDeps)
});
Object.defineProperty(group, 'dispose', {
enumerable: false,
value: _makeDisposeFn(group)
});
Object.freeze(group);
return group;
}
function channels (fns, context) {
fns = mapValues(fns, function createHandle (fn) {
return Delegator.allocateHandle(fn.bind(null, context))
})
Object.defineProperty(fns, 'toJSON', {
value: noop,
writable: true,
configurable: true,
enumerable: false
})
return fns
}
.map((selectedCountries) =>
mapValues(
indexBy(selectedCountries, 'code'),
({ popularity }) => popularity
)
return function read (callback) {
assert(++attempts <= 1, 'storage can only be read once')
return parallel(map(keys, Get), callback)
}