Add event_stream for events with many consumers.

Telegram/SourceFiles/base/algorithm_tests.cpp

@@ -0,0 +1,54 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop version of Telegram messaging app, see https://telegram.org
+
+Telegram Desktop is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+It is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+In addition, as a special exception, the copyright holders give permission
+to link the code of portions of this program with the OpenSSL library.
+
+Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
+Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
+*/
+#include "catch.hpp"
+
+#include "base/algorithm.h"
+
+TEST_CASE("push_back_safe_remove_if tests", "[base::algorithm]") {
+	auto v = std::vector<int>();
+
+	SECTION("doesn't change an empty vector") {
+		base::push_back_safe_remove_if(v, [](int) { return true; });
+		REQUIRE(v.empty());
+	}
+
+	v.insert(v.end(), { 1, 2, 3, 4, 5, 4, 3, 2, 1 });
+
+	SECTION("allows to push_back from predicate") {
+		base::push_back_safe_remove_if(v, [&v](int value) {
+			v.push_back(value);
+			return (value % 2) == 1;
+		});
+		auto expected = std::vector<int> { 2, 4, 4, 2, 1, 2, 3, 4, 5, 4, 3, 2, 1 };
+		REQUIRE(v == expected);
+	}
+
+	SECTION("allows to push_back while removing all") {
+		base::push_back_safe_remove_if(v, [&v](int value) {
+			if (value == 5) {
+				v.push_back(value);
+			}
+			return true;
+		});
+		auto expected = std::vector<int> { 5 };
+		REQUIRE(v == expected);
+	}
+}