110 lines
2.9 KiB
C++
110 lines
2.9 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2011-2014 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef CRUFT_UTIL_TYPES_HPP
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#define CRUFT_UTIL_TYPES_HPP
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#include <cstdint>
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#include <cstdlib>
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#include <memory>
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#include <stdexcept>
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#include <tuple>
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///////////////////////////////////////////////////////////////////////////////
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// analogue of std::data for use until we get proper c++17 support
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namespace util {
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template <typename T>
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auto
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data (T &t)
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{ return t.data (); }
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//-------------------------------------------------------------------------
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template <typename T>
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auto
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data (const T &t)
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{ return t.data (); }
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//-------------------------------------------------------------------------
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template <typename T, size_t N>
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constexpr T*
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data (T (&t)[N])
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{ return &t[0]; }
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//-------------------------------------------------------------------------
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template <typename T, size_t N>
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constexpr const T*
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data (const T (&t)[N])
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{ return &t[0]; }
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}
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///////////////////////////////////////////////////////////////////////////////
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/// returns the first argument from a parameter pack which can evaluate to true.
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template <class T>
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T
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first (T a)
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{
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if (a)
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return a;
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throw std::logic_error ("no valid object");
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}
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//-----------------------------------------------------------------------------
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template <class T, class ...Args>
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T
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first (T a, Args&& ...b)
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{
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if (a)
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return a;
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return first (std::forward<Args>(b)...);
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}
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namespace util {
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///------------------------------------------------------------------------
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/// represents a type as a POD struct (but is statically recoverable via
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/// the 'type' member).
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template <typename T>
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struct type_tag
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{
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typedef T type;
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};
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///------------------------------------------------------------------------
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/// count the number of parameters we are given. useful for counting
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/// arguments in variadic macros (ie, sizeof... (__VA_ARGS__))
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template <typename ...T>
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constexpr size_t
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param_count (const T... t)
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{
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// prevent unused variable warnings by never forwarding recursively
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// ideally we'd use void casting, but it doesn't work for parameter
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// packs
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if (false)
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return param_count (t...);
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return sizeof... (t);
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}
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}
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#endif
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