138 lines
4.2 KiB
C++
138 lines
4.2 KiB
C++
/*
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* This file is part of libgim.
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*
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* libgim is free software: you can redistribute it and/or modify it under the
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* terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* libgim is distributed in the hope that it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License
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* along with libgim. If not, see <http://www.gnu.org/licenses/>.
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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_HARD (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_HARD (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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namespace detail {
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// Same sign, no possibility of truncation with larger target type
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template <typename T, typename V>
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T
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_trunc_cast (const typename std::enable_if<sizeof (T) >= sizeof (V) &&
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std::is_signed<T>::value == std::is_signed<V>::value, V>::type v)
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{ return v; }
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template <typename T, typename V>
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T
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_trunc_cast (const typename std::enable_if<sizeof (T) < sizeof (V) &&
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std::is_signed<T>::value == std::is_signed<V>::value &&
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std::is_integral<T>::value, V>::type v) {
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CHECK_HARD (v <= std::numeric_limits<T>::max ());
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CHECK_HARD (v >= std::numeric_limits<T>::lowest ());
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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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_trunc_cast (const typename std::enable_if<sizeof (T) < sizeof (V) &&
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std::is_signed<T>::value == std::is_signed<V>::value &&
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std::is_floating_point<T>::value, V>::type v) {
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CHECK_HARD (v <= std::numeric_limits<T>::max ());
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CHECK_HARD (v >= std::numeric_limits<T>::lowest ());
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CHECK_HARD (exactly_equal (remainder (v, 1), 0.0));
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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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trunc_cast (V v)
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{ return detail::_trunc_cast<T, V> (v); }
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//-----------------------------------------------------------------------------
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template <typename T, typename V>
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T
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size_cast (const V v) {
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CHECK_HARD (std::numeric_limits<T>::lowest () <= v);
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CHECK_HARD (std::numeric_limits<T>::max () >= 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_HARD (nullptr != dynamic_cast<T*> (v));
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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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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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