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| -rw-r--r-- | src/common/sfinae_helpers.h | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/src/common/sfinae_helpers.h b/src/common/sfinae_helpers.h new file mode 100644 index 000000000..ddd456dd2 --- /dev/null +++ b/src/common/sfinae_helpers.h @@ -0,0 +1,147 @@ +// Copyright (c) 2016-2017, The Monero Project +// +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without modification, are +// permitted provided that the following conditions are met: +// +// 1. Redistributions of source code must retain the above copyright notice, this list of +// conditions and the following disclaimer. +// +// 2. Redistributions in binary form must reproduce the above copyright notice, this list +// of conditions and the following disclaimer in the documentation and/or other +// materials provided with the distribution. +// +// 3. Neither the name of the copyright holder nor the names of its contributors may be +// used to endorse or promote products derived from this software without specific +// prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY +// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF +// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL +// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, +// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, +// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF +// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#pragma once + +// the loose definitions of types in this file are, well, loose. +// +// these helpers aren't here for absolute type certainty at compile-time, +// but rather to help with templated functions telling types apart. + +namespace sfinae +{ + + typedef char true_type; + + struct false_type { true_type a[2]; }; + + template <typename T> + struct is_not_container + { + private: + + // does not have const iterator + template <typename C> static false_type c_iter(typename C::const_iterator*); + template <typename C> static true_type c_iter(...); + + // does not have value_type + template <typename C> static false_type v_type(typename C::value_type*); + template <typename C> static true_type v_type(...); + + // does not have key_type + template <typename C> static false_type k_type(typename C::key_type*); + template <typename C> static true_type k_type(...); + + // does not have mapped_type + template <typename C> static false_type m_type(typename C::mapped_type*); + template <typename C> static true_type m_type(...); + + public: + + static const bool value = ( + ( + sizeof(c_iter<T>(0)) == sizeof(true_type) && + sizeof(v_type<T>(0)) == sizeof(true_type) && + sizeof(k_type<T>(0)) == sizeof(true_type) && + sizeof(m_type<T>(0)) == sizeof(true_type) + ) + || std::is_same<T, std::string>::value + ); + + typedef T type; + }; + + template <typename T> + struct is_vector_like + { + private: + + // has const iterator + template <typename C> static true_type c_iter(typename C::const_iterator*); + template <typename C> static false_type c_iter(...); + + // has value_type + template <typename C> static true_type v_type(typename C::value_type*); + template <typename C> static false_type v_type(...); + + // does not have key_type + template <typename C> static false_type k_type(typename C::key_type*); + template <typename C> static true_type k_type(...); + + // does not have mapped_type + template <typename C> static false_type m_type(typename C::mapped_type*); + template <typename C> static true_type m_type(...); + + public: + + static const bool value = ( + sizeof(c_iter<T>(0)) == sizeof(true_type) && + sizeof(v_type<T>(0)) == sizeof(true_type) && + sizeof(k_type<T>(0)) == sizeof(true_type) && + sizeof(m_type<T>(0)) == sizeof(true_type) && + !std::is_same<T, std::string>::value + ); + + typedef T type; + }; + + template <typename T> + struct is_map_like + { + private: + + // has const iterator + template <typename C> static true_type c_iter(typename C::const_iterator*); + template <typename C> static false_type c_iter(...); + + // has value_type + template <typename C> static true_type v_type(typename C::value_type*); + template <typename C> static false_type v_type(...); + + // has key_type + template <typename C> static true_type k_type(typename C::key_type*); + template <typename C> static false_type k_type(...); + + // has mapped_type + template <typename C> static true_type m_type(typename C::mapped_type*); + template <typename C> static false_type m_type(...); + + public: + + static const bool value = ( + sizeof(c_iter<T>(0)) == sizeof(true_type) && + sizeof(v_type<T>(0)) == sizeof(true_type) && + sizeof(k_type<T>(0)) == sizeof(true_type) && + sizeof(m_type<T>(0)) == sizeof(true_type) && + !std::is_same<T, std::string>::value + ); + + typedef T type; + }; + +} // namespace sfinae |