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/**
* Copyright (c) 2013-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @providesModule countDistinct
* @flow
*/
'use strict';
var Set = require('./Set');
var emptyFunction = require('./emptyFunction');
/**
* Returns the count of distinct elements selected from an array.
*/
function countDistinct<T1, T2>(iter: Iterable<T1>, selector: (item: T1) => T2): number {
selector = selector || emptyFunction.thatReturnsArgument;
var set = new Set();
for (var val of iter) {
set.add(selector(val));
}
return set.size;
}
module.exports = countDistinct;
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