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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0+ OR GPL-3.0 WITH Qt-GPL-exception-1.0
#pragma once
#include <tuple>
namespace Utils {
/*
struct functionTraits<Function>
{
using ResultType; // Return type of Function
struct argument<unsigned index>
{
using type; // type of Function argument at index (starting with 0)
}
}
struct functionTakesArgument<Function, unsigned index, ArgumentType>;
Is derived from std::true_type if Function takes an argument of type ArgumentType at index.
Otherwise derived from std::false_type.
*/
////////////////////
// functionTraits
////////////////////
// for callables. defined below.
template <typename Callable>
struct functionTraits;
// function
template <typename Result, typename... Args>
struct functionTraits<Result(Args...)>
{
using ResultType = Result;
static const unsigned arity = sizeof...(Args); // TODO const -> constexpr with MSVC2015
template <unsigned i>
struct argument
{
using type = typename std::tuple_element<i, std::tuple<Args...>>::type;
};
};
// function pointer
template <typename Result, typename... Args>
struct functionTraits<Result(*)(Args...)> : public functionTraits<Result(Args...)>
{
};
// const function pointer
template <typename Result, typename... Args>
struct functionTraits<Result(* const)(Args...)> : public functionTraits<Result(Args...)>
{
};
// member function
template <typename Type, typename Result, typename... Args>
struct functionTraits<Result(Type::*)(Args...)> : public functionTraits<Result(Type&,Args...)>
{
};
// const member function
template <typename Type, typename Result, typename... Args>
struct functionTraits<Result(Type::*)(Args...) const> : public functionTraits<Result(Type&,Args...)>
{
};
// const pointer to member function
template <typename Type, typename Result, typename... Args>
struct functionTraits<Result(Type::* const)(Args...)> : public functionTraits<Result(Type&,Args...)>
{
};
// const pointer to const member function
template <typename Type, typename Result, typename... Args>
struct functionTraits<Result(Type::* const)(Args...) const> : public functionTraits<Result(Type&,Args...)>
{
};
// TODO: enable lvalue and rvalue ref member function later (MSVC 2015?)
//// lvalue ref member function
//template <typename Type, typename Result, typename... Args>
//struct functionTraits<Result(Type::*)(Args...) &> : public functionTraits<Result(Type&,Args...)>
//{
//};
//// const lvalue ref member function
//template <typename Type, typename Result, typename... Args>
//struct functionTraits<Result(Type::*)(Args...) const &> : public functionTraits<Result(Type&,Args...)>
//{
//};
//// rvalue ref member function
//template <typename Type, typename Result, typename... Args>
//struct functionTraits<Result(Type::*)(Args...) &&> : public functionTraits<Result(Type&,Args...)>
//{
//};
// callables. only works if operator() is not overloaded.
template <typename Callable>
struct functionTraits
{
using callableTraits = functionTraits<decltype(&Callable::operator())>;
using ResultType = typename callableTraits::ResultType;
static const unsigned arity = callableTraits::arity - 1; // ignore object pointer arg // TODO const -> constexpr with MSVC2015
template <unsigned i>
struct argument
{
using type = typename callableTraits::template argument<i+1>::type; // ignore object pointer arg
};
};
// lvalue ref callables
template <typename Callable>
struct functionTraits<Callable&> : public functionTraits<Callable>
{
};
// const lvalue ref callables
template <typename Callable>
struct functionTraits<const Callable&> : public functionTraits<Callable>
{
};
// rvalue ref callables
template <typename Callable>
struct functionTraits<Callable&&> : public functionTraits<Callable>
{
};
template <typename F>
using functionResult_t = typename functionTraits<F>::ResultType;
////////////////////
// functionTakesArgument
////////////////////
namespace Internal {
template <typename HasArity/*true_type or false_type*/,
typename Function, unsigned index, typename T>
struct functionTakesArgumentArityDispatch;
template <typename Function, unsigned index, typename T>
struct functionTakesArgumentArityDispatch<std::false_type, Function, index, T>
: public std::false_type
{
};
template <typename Function, unsigned index, typename T>
struct functionTakesArgumentArityDispatch<std::true_type, Function, index, T>
: public std::is_same<T, typename functionTraits<Function>::template argument<index>::type>
{
};
} // Internal
template <typename Function, unsigned index, typename T>
struct functionTakesArgument : public Internal::functionTakesArgumentArityDispatch<
std::integral_constant<bool, (functionTraits<Function>::arity > index)>,
Function, index, T>
{
};
} // Utils
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