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// MPark.Variant
//
// Copyright Michael Park, 2015-2017
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
#include <mpark/variant.hpp>
#include <string>
#include <sstream>
#include <gtest/gtest.h>
#include "util.hpp"
TEST(Assign_Fwd, SameType) {
mpark::variant<int, std::string> v(101);
EXPECT_EQ(101, mpark::get<int>(v));
v = 202;
EXPECT_EQ(202, mpark::get<int>(v));
}
TEST(Assign_Fwd, SameTypeFwd) {
mpark::variant<int, std::string> v(1.1);
EXPECT_EQ(1, mpark::get<int>(v));
v = 2.2;
EXPECT_EQ(2, mpark::get<int>(v));
}
TEST(Assign_Fwd, DiffType) {
mpark::variant<int, std::string> v(42);
EXPECT_EQ(42, mpark::get<int>(v));
v = "42";
EXPECT_EQ("42", mpark::get<std::string>(v));
}
TEST(Assign_Fwd, DiffTypeFwd) {
mpark::variant<int, std::string> v(42);
EXPECT_EQ(42, mpark::get<int>(v));
v = "42";
EXPECT_EQ("42", mpark::get<std::string>(v));
}
TEST(Assign_Fwd, ExactMatch) {
mpark::variant<const char *, std::string> v;
v = std::string("hello");
EXPECT_EQ("hello", mpark::get<std::string>(v));
}
TEST(Assign_Fwd, BetterMatch) {
mpark::variant<int, double> v;
// `char` -> `int` is better than `char` -> `double`
v = 'x';
EXPECT_EQ(static_cast<int>('x'), mpark::get<int>(v));
}
TEST(Assign_Fwd, NoMatch) {
struct x {};
static_assert(!std::is_assignable<mpark::variant<int, std::string>, x>{},
"variant<int, std::string> v; v = x;");
}
TEST(Assign_Fwd, Ambiguous) {
static_assert(!std::is_assignable<mpark::variant<short, long>, int>{},
"variant<short, long> v; v = 42;");
}
TEST(Assign_Fwd, SameTypeOptimization) {
mpark::variant<int, std::string> v("hello world!");
// Check `v`.
const std::string &x = mpark::get<std::string>(v);
EXPECT_EQ("hello world!", x);
// Save the "hello world!"'s capacity.
auto capacity = x.capacity();
// Use `std::string::operator=(const char *)` to assign into `v`.
v = "hello";
// Check `v`.
const std::string &y = mpark::get<std::string>(v);
EXPECT_EQ("hello", y);
// Since "hello" is shorter than "hello world!", we should have preserved the
// existing capacity of the string!.
EXPECT_EQ(capacity, y.capacity());
}
#ifdef MPARK_EXCEPTIONS
TEST(Assign_Fwd, ThrowOnAssignment) {
mpark::variant<int, move_thrower_t> v(
mpark::in_place_type_t<move_thrower_t>{});
// Since `variant` is already in `move_thrower_t`, assignment optimization
// kicks and we simply invoke
// `move_thrower_t &operator=(move_thrower_t &&);` which throws.
EXPECT_THROW(v = move_thrower_t{}, MoveAssignment);
EXPECT_FALSE(v.valueless_by_exception());
EXPECT_EQ(1u, v.index());
// We can still assign into a variant in an invalid state.
v = 42;
// Check `v`.
EXPECT_FALSE(v.valueless_by_exception());
EXPECT_EQ(42, mpark::get<int>(v));
}
#endif
#if 0
TEST(Assign_Fwd, ThrowOnTemporaryConstruction) {
mpark::variant<int, copy_thrower_t> v(42);
// Since `copy_thrower_t`'s copy constructor always throws, we will fail to
// construct the variant. This results in our variant staying in
// its original state.
copy_thrower_t copy_thrower{};
EXPECT_THROW(v = copy_thrower, CopyConstruction);
EXPECT_FALSE(v.valueless_by_exception());
EXPECT_EQ(0u, v.index());
EXPECT_EQ(42, mpark::get<int>(v));
}
TEST(Assign_Fwd, ThrowOnVariantConstruction) {
mpark::variant<int, move_thrower_t> v(42);
// Since `move_thrower_t`'s copy constructor never throws, we successfully
// construct the temporary object by copying `move_thrower_t`. We then
// proceed to move the temporary object into our variant, at which point
// `move_thrower_t`'s move constructor throws. This results in our `variant`
// transitioning into the invalid state.
move_thrower_t move_thrower;
EXPECT_THROW(v = move_thrower, MoveConstruction);
EXPECT_TRUE(v.valueless_by_exception());
// We can still assign into a variant in an invalid state.
v = 42;
// Check `v`.
EXPECT_FALSE(v.valueless_by_exception());
EXPECT_EQ(42, mpark::get<int>(v));
}
#endif
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