blob: 3c198714fc854a38f612e0f7053656aaac4dbcd3 [file] [log] [blame]
// Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
/// @assertion
/// T fold <T>(T initialValue, T combine(T previousValue, E element))
/// Reduces a collection to a single value by iteratively combining each element
/// of the collection with an existing value
/// Uses initialValue as the initial value, then iterates through the elements
/// and updates the value with each element using the combine function, as if by:
///
/// var value = initialValue;
/// for (E element in this) {
/// value = combine(value, element);
/// }
/// return value;
/// Example of calculating the sum of an iterable:
/// iterable.fold(0, (prev, element) => prev + element);
/// @description Checks that fold is called for each element of this Iterable
/// @author sgrekhov@unipro.ru
library fold_A01_t02;
import "../../../Utils/expect.dart";
num combine(num previousValue, element) => ++previousValue;
check(Iterable a) {
num actual = a.fold(0, combine);
Expect.equals(a.length, actual);
}
test(Iterable create([Iterable content])) {
check(create([]));
check(create([1]));
check(create([0, 0, 0]));
check(create([1, 2, 3, 4, 5, 6, 7, 8]));
}