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Diffstat (limited to 'src/third_party/boost-1.69.0/boost/type_traits/detail/is_likely_lambda.hpp')
-rw-r--r-- | src/third_party/boost-1.69.0/boost/type_traits/detail/is_likely_lambda.hpp | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/src/third_party/boost-1.69.0/boost/type_traits/detail/is_likely_lambda.hpp b/src/third_party/boost-1.69.0/boost/type_traits/detail/is_likely_lambda.hpp new file mode 100644 index 00000000000..39aa5281145 --- /dev/null +++ b/src/third_party/boost-1.69.0/boost/type_traits/detail/is_likely_lambda.hpp @@ -0,0 +1,94 @@ +/* Copyright 2017 Joaquin M Lopez Munoz. + * Distributed under the Boost Software License, Version 1.0. + * (See accompanying file LICENSE_1_0.txt or copy at + * http://www.boost.org/LICENSE_1_0.txt) + * + * See http://www.boost.org/libs/poly_collection for library home page. + */ + +#ifndef BOOST_TT_DETAIL_IS_LIKELY_STATELESS_LAMBDA_HPP +#define BOOST_TT_DETAIL_IS_LIKELY_STATELESS_LAMBDA_HPP + +#if defined(_MSC_VER) +#pragma once +#endif + +#include <boost/type_traits/detail/config.hpp> +#include <boost/type_traits/integral_constant.hpp> + +#if defined(BOOST_TT_HAS_ACCURATE_BINARY_OPERATOR_DETECTION) +// +// We don't need or use this, just define a dummy class: +// +namespace boost{ namespace type_traits_detail{ + +template<typename T> +struct is_likely_stateless_lambda : public false_type {}; + +}} + +#elif !defined(BOOST_NO_CXX11_LAMBDAS) && !defined(BOOST_NO_CXX11_DECLTYPE) && !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES) && !BOOST_WORKAROUND(BOOST_MSVC, < 1900) + +#include <boost/type_traits/is_convertible.hpp> +#include <boost/type_traits/enable_if.hpp> + +namespace boost{ + +namespace type_traits_detail{ + +/* Stateless lambda expressions have one (and only one) call operator and are + * convertible to a function pointer with the same signature. Non-lambda types + * could satisfy this too, hence the "likely" qualifier. + */ + +template<typename T> +struct has_one_operator_call_helper +{ + template<typename Q> static boost::true_type test(decltype(&Q::operator())*); + template<typename> static boost::false_type test(...); + + using type=decltype(test<T>(nullptr)); +}; + +template<typename T> +using has_one_operator_call=typename has_one_operator_call_helper<T>::type; + +template<typename T> +struct equivalent_function_pointer +{ + template<typename Q,typename R,typename... Args> + static auto helper(R (Q::*)(Args...)const)->R(*)(Args...); + template<typename Q,typename R,typename... Args> + static auto helper(R (Q::*)(Args...))->R(*)(Args...); + + using type=decltype(helper(&T::operator())); +}; + +template<typename T,typename=void> +struct is_likely_stateless_lambda : false_type{}; + +template<typename T> +struct is_likely_stateless_lambda< + T, + typename boost::enable_if_<has_one_operator_call<T>::value>::type> : + boost::is_convertible<T, typename equivalent_function_pointer<T>::type +>{}; + +} /* namespace type_traits_detail */ + +} /* namespace boost */ + +#else + // + // Can't implement this: + // +namespace boost { + namespace type_traits_detail { + + template<typename T> + struct is_likely_stateless_lambda : public boost::integral_constant<bool, false> {}; +}} + +#endif +#endif + |