Implement boost::exchange

test/exchange_test.cpp

@@ -0,0 +1,65 @@
+/*
+Copyright 2018 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#include <boost/core/exchange.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+void test1()
+{
+    int i = 1;
+    BOOST_TEST(boost::exchange(i, 2) == 1);
+    BOOST_TEST(i == 2);
+}
+
+class C1 {
+public:
+    explicit C1(int i)
+        : i_(i) { }
+    int i() const {
+        return i_;
+    }
+private:
+    int i_;
+};
+
+void test2()
+{
+    C1 x(1);
+    BOOST_TEST(boost::exchange(x, C1(2)).i() == 1);
+    BOOST_TEST(x.i() == 2);
+}
+
+class C2 {
+public:
+    explicit C2(int i)
+        : i_(i) { }
+    operator C1() const {
+        return C1(i_);
+    }
+    int i() const {
+        return i_;
+    }
+private:
+    C2(const C2&);
+    C2& operator=(const C2&);
+    int i_;
+};
+
+void test3()
+{
+    C1 x(1);
+    BOOST_TEST(boost::exchange(x, C2(2)).i() == 1);
+    BOOST_TEST(x.i() == 2);
+}
+
+int main()
+{
+    test1();
+    test2();
+    test3();
+    return boost::report_errors();
+}