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 // Copyright (c) 2011, 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 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 the result is correct for simple functions. /// @author kaigorodov library fold_A01_t01; import "dart:math"; import "../../../Utils/expect.dart"; check(Iterable a, num init, combine, num expected) { num actual = a.fold(init, combine); Expect.equals(expected, actual); } test(Iterable create([Iterable content])) { check(create([1, 2, -3]), 0, (num value, element) => value + element, 0); check(create([1, 2, -3]), 1, (num value, element) => value * element, -6); check(create([0, 2, -3]), 1, (num value, element) => value * element, 0); check(create([1, 2, -5, -6]), -1000, (num value, element) => max(value, element as int), 2); }