gecko/mfbt/tests/TestTypeTraits.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "mozilla/Assertions.h"
#include "mozilla/TypeTraits.h"

using mozilla::IsBaseOf;
using mozilla::IsConvertible;

namespace CPlusPlus11IsBaseOf {

// Adapted from C++11 § 20.9.6.
struct B {};
struct B1 : B {};
struct B2 : B {};
struct D : private B1, private B2 {};

static void
StandardIsBaseOfTests()
{
  MOZ_ASSERT((IsBaseOf<B, D>::value) == true);
  MOZ_ASSERT((IsBaseOf<const B, D>::value) == true);
  MOZ_ASSERT((IsBaseOf<B, const D>::value) == true);
  MOZ_ASSERT((IsBaseOf<B, const B>::value) == true);
  MOZ_ASSERT((IsBaseOf<D, B>::value) == false);
  MOZ_ASSERT((IsBaseOf<B&, D&>::value) == false);
  MOZ_ASSERT((IsBaseOf<B[3], D[3]>::value) == false);
  // We fail at the following test.  To fix it, we need to specialize IsBaseOf
  // for all built-in types.
  // MOZ_ASSERT((IsBaseOf<int, int>::value) == false);
}

} /* namespace CPlusPlus11IsBaseOf */

class A { };
class B : public A { };
class C : private A { };
class D { };
class E : public A { };
class F : public B, public E { };

static void
TestIsBaseOf()
{
  MOZ_ASSERT((IsBaseOf<A, B>::value),
             "A is a base of B");
  MOZ_ASSERT((!IsBaseOf<B, A>::value),
             "B is not a base of A");
  MOZ_ASSERT((IsBaseOf<A, C>::value),
             "A is a base of C");
  MOZ_ASSERT((!IsBaseOf<C, A>::value),
             "C is not a base of A");
  MOZ_ASSERT((IsBaseOf<A, F>::value),
             "A is a base of F");
  MOZ_ASSERT((!IsBaseOf<F, A>::value),
             "F is not a base of A");
  MOZ_ASSERT((!IsBaseOf<A, D>::value),
             "A is not a base of D");
  MOZ_ASSERT((!IsBaseOf<D, A>::value),
             "D is not a base of A");
  MOZ_ASSERT((IsBaseOf<B, B>::value),
             "B is the same as B (and therefore, a base of B)");
}

static void
TestIsConvertible()
{
  // Pointer type convertibility
  MOZ_ASSERT((IsConvertible<A*, A*>::value),
             "A* should convert to A*");
  MOZ_ASSERT((IsConvertible<B*, A*>::value),
             "B* should convert to A*");
  MOZ_ASSERT((!IsConvertible<A*, B*>::value),
             "A* shouldn't convert to B*");
  MOZ_ASSERT((!IsConvertible<A*, C*>::value),
             "A* shouldn't convert to C*");
  MOZ_ASSERT((!IsConvertible<A*, D*>::value),
             "A* shouldn't convert to unrelated D*");
  MOZ_ASSERT((!IsConvertible<D*, A*>::value),
             "D* shouldn't convert to unrelated A*");

  // Instance type convertibility
  MOZ_ASSERT((IsConvertible<A, A>::value),
             "A is A");
  MOZ_ASSERT((IsConvertible<B, A>::value),
             "B converts to A");
  MOZ_ASSERT((!IsConvertible<D, A>::value),
             "D and A are unrelated");
  MOZ_ASSERT((!IsConvertible<A, D>::value),
             "A and D are unrelated");

  // These cases seem to require C++11 support to properly implement them, so
  // for now just disable them.
  //MOZ_ASSERT((!IsConvertible<C*, A*>::value),
  //           "C* shouldn't convert to A* (private inheritance)");
  //MOZ_ASSERT((!IsConvertible<C, A>::value),
  //           "C doesn't convert to A (private inheritance)");
}

int
main()
{
  CPlusPlus11IsBaseOf::StandardIsBaseOfTests();
  TestIsBaseOf();
  TestIsConvertible();
}