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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <type_traits>
#include "mozilla/Assertions.h"
#include "mozilla/CompactPair.h"
using mozilla::CompactPair;
using mozilla::MakeCompactPair;
// Sizes aren't part of the guaranteed CompactPair interface, but we want to
// verify our attempts at compactness through EBO are moderately functional,
// *somewhere*.
#define INSTANTIATE(T1, T2, name, size) \
CompactPair<T1, T2> name##_1(T1(0), T2(0)); \
static_assert(sizeof(name##_1.first()) > 0, \
"first method should work on CompactPair<" #T1 ", " #T2 ">"); \
\
static_assert(sizeof(name##_1.second()) > 0, \
"second method should work on CompactPair<" #T1 ", " #T2 ">"); \
\
static_assert(sizeof(name##_1) == (size), \
"CompactPair<" #T1 ", " #T2 "> has an unexpected size"); \
\
CompactPair<T2, T1> name##_2(T2(0), T1(0)); \
static_assert(sizeof(name##_2.first()) > 0, \
"first method should work on CompactPair<" #T2 ", " #T1 ">"); \
\
static_assert(sizeof(name##_2.second()) > 0, \
"second method should work on CompactPair<" #T2 ", " #T1 ">"); \
\
static_assert(sizeof(name##_2) == (size), \
"CompactPair<" #T2 ", " #T1 "> has an unexpected size");
static constexpr std::size_t sizemax(std::size_t a, std::size_t b) {
return (a > b) ? a : b;
}
INSTANTIATE(int, int, prim1, 2 * sizeof(int));
INSTANTIATE(int, long, prim2,
sizeof(long) + sizemax(sizeof(int), alignof(long)));
struct EmptyClass {
explicit EmptyClass(int) {}
};
struct NonEmpty {
char mC;
explicit NonEmpty(int) : mC('\0') {}
};
INSTANTIATE(int, EmptyClass, both1, sizeof(int));
INSTANTIATE(int, NonEmpty, both2, sizeof(int) + alignof(int));
INSTANTIATE(EmptyClass, NonEmpty, both3, 1);
struct A {
char dummy;
explicit A(int) : dummy('\0') {}
};
struct B : A {
explicit B(int aI) : A(aI) {}
};
INSTANTIATE(A, A, class1, 2);
INSTANTIATE(A, B, class2, 2);
INSTANTIATE(A, EmptyClass, class3, 1);
struct EmptyNonMovableNonDefaultConstructible {
explicit EmptyNonMovableNonDefaultConstructible(int) {}
EmptyNonMovableNonDefaultConstructible(
const EmptyNonMovableNonDefaultConstructible&) = delete;
EmptyNonMovableNonDefaultConstructible(
EmptyNonMovableNonDefaultConstructible&&) = delete;
EmptyNonMovableNonDefaultConstructible& operator=(
const EmptyNonMovableNonDefaultConstructible&) = delete;
EmptyNonMovableNonDefaultConstructible& operator=(
EmptyNonMovableNonDefaultConstructible&&) = delete;
};
static void TestInPlaceConstruction() {
constexpr int firstValue = 42;
constexpr int secondValue = 43;
{
const CompactPair<EmptyNonMovableNonDefaultConstructible, int> pair{
std::piecewise_construct, std::tuple(firstValue),
std::tuple(secondValue)};
MOZ_RELEASE_ASSERT(pair.second() == secondValue);
}
{
const CompactPair<int, EmptyNonMovableNonDefaultConstructible> pair{
std::piecewise_construct, std::tuple(firstValue),
std::tuple(secondValue)};
MOZ_RELEASE_ASSERT(pair.first() == firstValue);
}
{
const CompactPair<int, int> pair{std::piecewise_construct,
std::tuple(firstValue),
std::tuple(secondValue)};
MOZ_RELEASE_ASSERT(pair.first() == firstValue);
MOZ_RELEASE_ASSERT(pair.second() == secondValue);
}
{
const CompactPair<EmptyNonMovableNonDefaultConstructible,
EmptyNonMovableNonDefaultConstructible>
pair{std::piecewise_construct, std::tuple(firstValue),
std::tuple(secondValue)};
// nothing to assert here...
}
}
struct OtherEmpty : EmptyClass {
explicit OtherEmpty(int aI) : EmptyClass(aI) {}
};
// C++11 requires distinct objects of the same type, within the same "most
// derived object", to have different addresses. CompactPair allocates its
// elements as two bases, a base and a member, or two members. If the two
// elements have non-zero size or are unrelated, no big deal. But if they're
// both empty and related, something -- possibly both -- must be inflated.
// Exactly which are inflated depends which CompactPairHelper specialization is
// used. We could potentially assert something about size for this case, but
// whatever we could assert would be very finicky. Plus it's two empty classes
// -- hardly likely. So don't bother trying to assert anything about this case.
// INSTANTIATE(EmptyClass, OtherEmpty, class4, ...something finicky...);
int main() {
A a(0);
B b(0);
const A constA(0);
const B constB(0);
// Check that MakeCompactPair generates CompactPair objects of the correct
// types.
static_assert(
std::is_same_v<decltype(MakeCompactPair(A(0), B(0))), CompactPair<A, B>>,
"MakeCompactPair should strip rvalue references");
static_assert(
std::is_same_v<decltype(MakeCompactPair(a, b)), CompactPair<A, B>>,
"MakeCompactPair should strip lvalue references");
static_assert(std::is_same_v<decltype(MakeCompactPair(constA, constB)),
CompactPair<A, B>>,
"MakeCompactPair should strip CV-qualifiers");
// Check that copy assignment and move assignment work.
a = constA;
a = A(0);
TestInPlaceConstruction();
return 0;
}
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