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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include <vespa/vespalib/testkit/test_kit.h>
#include <functional>
TEST("verify how std::function copies lambda closures") {
size_t count = 0;
size_t value = 0;
auto closure = [count,&value]()mutable{ ++count; value += count; };
closure();
EXPECT_EQUAL(0u, count);
EXPECT_EQUAL(1u, value); // +1
closure();
EXPECT_EQUAL(3u, value); // +2
std::function<void()> fun = closure;
fun();
EXPECT_EQUAL(6u, value); // +3
closure();
EXPECT_EQUAL(9u, value); // +3 (fun had a copy of count)
auto &closure_ref = closure;
std::function<void()> fun2 = closure_ref;
fun2();
EXPECT_EQUAL(13u, value); // +4
closure();
EXPECT_EQUAL(17u, value); // +4 (fun2 had a copy of count)
std::function<void()> fun3 = std::ref(closure);
fun3();
EXPECT_EQUAL(22u, value); // +5
closure();
EXPECT_EQUAL(28u, value); // +6 (fun only had a copy of the wrapper)
}
TEST_MAIN() { TEST_RUN_ALL(); }
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