1 files changed, 33 insertions, 0 deletions
diff --git a/node_modules/fbjs/lib/countDistinct.js.flow b/node_modules/fbjs/lib/countDistinct.js.flow
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+++ b/node_modules/fbjs/lib/countDistinct.js.flow
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+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @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;
+\ No newline at end of file