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8250652: Add logical operations on types
Add stand-ins for C++17 logical operations on types.

Reviewed-by: eosterlund, tschatzl
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Kim Barrett committed Aug 4, 2020
1 parent 52ac1c3 commit 37fb43c89e8d1508125b473a476291828060348f
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/*
* Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/

#ifndef SHARE_METAPROGRAMMING_LOGICAL_HPP
#define SHARE_METAPROGRAMMING_LOGICAL_HPP

// Stand-ins for C++17 logical operations on types.

#include <type_traits>

// Stand-in for C++17 std::bool_constant<value>.
template<bool Value>
using BoolConstant = std::integral_constant<bool, Value>;

// Stand-in for C++17 std::conjunction<T...>
template<typename... T>
struct Conjunction : public std::true_type {};

template<typename T1>
struct Conjunction<T1> : public T1 {};

template<typename T1, typename... T>
struct Conjunction<T1, T...> :
public std::conditional_t<bool(T1::value), Conjunction<T...>, T1>
{};

// Stand-in for C++17 std::disjunction<T...>.
template<typename... T>
struct Disjunction : public std::false_type {};

template<typename T1>
struct Disjunction<T1> : public T1 {};

template<typename T1, typename... T>
struct Disjunction<T1, T...> :
public std::conditional_t<bool(T1::value), T1, Disjunction<T...>>
{};

// Stand-in for C++17 std::negation<T>.
template<typename T>
using Negation = BoolConstant<!bool(T::value)>;

#endif // SHARE_METAPROGRAMMING_LOGICAL_HPP
@@ -0,0 +1,91 @@
/*
* Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/

#include "precompiled.hpp"
#include "metaprogramming/logical.hpp"
#include <type_traits>

class TestBoolConstant {
static_assert(BoolConstant<true>::value, "true");
static_assert(!BoolConstant<false>::value, "false");
};

class TestConjunction {
class A : public std::true_type {};
class B : public std::true_type {};
class C : public std::false_type {};
class D : public std::false_type {};

static_assert(Conjunction<>::value, "nullary value");

static_assert(Conjunction<A>::value, "true value");
static_assert(std::is_base_of<A, Conjunction<A>>::value, "true type");

static_assert(!Conjunction<C>::value, "false value");
static_assert(std::is_base_of<C, Conjunction<C>>::value, "false type");

static_assert(Conjunction<A, B>::value, "true/true value");
static_assert(std::is_base_of<B, Conjunction<A, B>>::value, "true/true type");

static_assert(!Conjunction<A, C>::value, "true/false value");
static_assert(std::is_base_of<C, Conjunction<A, C>>::value, "true/false type");

static_assert(!Conjunction<C, A>::value, "false/true value");
static_assert(std::is_base_of<C, Conjunction<C, A>>::value, "false/true type");

static_assert(!Conjunction<C, D>::value, "false/false value");
static_assert(std::is_base_of<C, Conjunction<C, D>>::value, "false/false type");
};

class TestDisjunction {
class A : public std::true_type {};
class B : public std::true_type {};
class C : public std::false_type {};
class D : public std::false_type {};

static_assert(!Disjunction<>::value, "nullary value");

static_assert(Disjunction<A>::value, "true value");
static_assert(std::is_base_of<A, Disjunction<A>>::value, "true type");

static_assert(!Disjunction<C>::value, "false value");
static_assert(std::is_base_of<C, Disjunction<C>>::value, "false type");

static_assert(Disjunction<A, B>::value, "true/true value");
static_assert(std::is_base_of<A, Disjunction<A, B>>::value, "true/true type");

static_assert(Disjunction<A, C>::value, "true/false value");
static_assert(std::is_base_of<A, Disjunction<A, C>>::value, "true/false type");

static_assert(Disjunction<C, A>::value, "false/true value");
static_assert(std::is_base_of<A, Disjunction<C, A>>::value, "false/true type");

static_assert(!Disjunction<C, D>::value, "false/false value");
static_assert(std::is_base_of<D, Disjunction<C, D>>::value, "false/false type");
};

class TestNegation {
static_assert(Negation<std::false_type>::value, "false -> true");
static_assert(!Negation<std::true_type>::value, "true -> false");
};

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