106 lines
3.0 KiB
C++
106 lines
3.0 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 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef __UTIL_TYPES_CASTS_HPP
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#define __UTIL_TYPES_CASTS_HPP
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#include "../debug.hpp"
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#include <type_traits>
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#include <limits>
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//-----------------------------------------------------------------------------
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namespace detail {
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template <typename T, typename V>
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T
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_sign_cast (const typename std::enable_if<sizeof(T) == sizeof(V) &&
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std::is_unsigned<T>::value &&
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std::is_signed<V>::value, V>::type v)
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{
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CHECK_GE (v, 0);
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return static_cast<T> (v);
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}
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template <typename T, typename V>
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T
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_sign_cast (const typename std::enable_if<sizeof(T) == sizeof(V) &&
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std::is_signed<T>::value &&
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std::is_unsigned<V>::value, V>::type v)
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{
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CHECK_LT (v, std::numeric_limits<V>::max () / 2);
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return static_cast<T> (v);
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}
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template <typename T, typename V>
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T
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_sign_cast (const typename std::enable_if<std::is_same<T, V>::value, V>::type v)
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{ return v; }
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}
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/// Safely cast a numeric type to its (un)signed counterpart, aborting if the
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/// dynamically checked result is not representable. May be optimised out if
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/// NDEBUG is defined.
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template <typename T, typename V>
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T
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sign_cast (const V v)
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{ return detail::_sign_cast<T,V>(v); }
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///----------------------------------------------------------------------------
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/// assert if the value cannot be cast loslessly from U to T, else return the
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/// converted value.Note: this is only a debug-time check and is compiled out
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/// in optimised builds.
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template <typename T, typename U>
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T
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trunc_cast (U u)
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{
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auto t = static_cast<T> (u);
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if (u == u)
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CHECK_EQ (t, u);
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else
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CHECK_NEQ (t, t);
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return t;
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}
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///----------------------------------------------------------------------------
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/// assert if the value is not a pointer to a subclass of T, else return the
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/// converted value. Note: this is only a debug-time check and is compiled out
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/// in optimised builds.
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template <typename T, typename V>
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T*
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known_cast (V *v) {
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CHECK (dynamic_cast<T*> (v));
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return static_cast<T*> (v);
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}
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//-----------------------------------------------------------------------------
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template <typename T, typename V>
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T&
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known_cast (V &v) {
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CHECK_NOTHROW (dynamic_cast<T> (v));
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return static_cast<T> (v);
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}
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#endif
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