145 lines
5.1 KiB
C++
145 lines
5.1 KiB
C++
/*=============================================================================
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This file is part of FLINT.
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FLINT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FLINT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FLINT; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2013 Tom Bachmann
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******************************************************************************/
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#ifndef CXX_TRAITS_H
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#define CXX_TRAITS_H
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// only for true_/false_
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#include "mp.h"
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namespace flint {
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namespace detail {
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template<class T>
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struct wrap
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{
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T t;
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};
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} // detail
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namespace traits {
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///////////////////////
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// BASIC TYPE TRAITS
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///////////////////////
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// These helpers can be used to manipulate and inquire type information.
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// For example, given an arbitrary type T, one might be interested in knowing
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// if it is an integral type (int, short, ulong, etc).
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//
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// This file contains generic traits, not specific to FLINT.
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using mp::true_;
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using mp::false_;
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// Compute if T belongs to the signed integer types.
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template<class T> struct is_signed_integer : false_ { };
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template<> struct is_signed_integer<signed char> : true_ { };
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template<> struct is_signed_integer<signed short> : true_ { };
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template<> struct is_signed_integer<signed int> : true_ { };
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template<> struct is_signed_integer<slong> : true_ { };
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// Compute if T belongs to the unsigned integer types.
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template<class T> struct is_unsigned_integer : false_ { };
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template<> struct is_unsigned_integer<unsigned char> : true_ { };
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template<> struct is_unsigned_integer<unsigned short> : true_ { };
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template<> struct is_unsigned_integer<unsigned int> : true_ { };
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template<> struct is_unsigned_integer<ulong> : true_ { };
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// Compute if T belongs to the signed or unsigned integer types
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template<class T> struct is_integer
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: mp::or_<is_unsigned_integer<T>, is_signed_integer<T> > { };
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// Compute if T can always losslessly be converted into an slong
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template<class T, class Enable = void> struct fits_into_slong : mp::false_ { };
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template<class T>
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struct fits_into_slong<T, typename mp::enable_if<traits::is_integer<T> >::type>
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: mp::or_<
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is_signed_integer<T>,
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mp::and_v<
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is_unsigned_integer<T>,
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sizeof(T) < sizeof(slong)
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>
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> { };
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template<class T> struct fits_into_mp_bitcnt_t : is_unsigned_integer<T> { };
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// Compute if T is like const char*
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template<class T> struct is_string : mp::false_ { };
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template<> struct is_string<char*> : mp::true_ { };
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template<> struct is_string<const char*> : mp::true_ { };
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template<int n> struct is_string<char[n]> : mp::true_ { };
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template<int n> struct is_string<const char[n]> : mp::true_ { };
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// Compute a type appropriate for forwarding T. This is just the appropriate
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// constant reference type (but avoids things like const (int&)&, which cause
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// syntax errors.
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template<class T, class E = void> struct forwarding {typedef const T& type;};
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template<class T> struct forwarding<T&> {typedef T& type;};
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template<class T> struct forwarding<const T&> {typedef const T& type;};
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template<class T>
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struct forwarding<T, typename mp::enable_if<is_integer<T> >::type>
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{
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typedef T type;
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};
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template<class T> struct forwarding<T*> {typedef T* type;};
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template<> struct forwarding<bool> {typedef bool type;};
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// Compute a type appropriate for referencing. Usually T&.
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template<class T> struct reference {typedef T& type;};
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template<class T> struct reference<T&> {typedef T& type;};
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template<class T> struct reference<const T&> {typedef const T& type;};
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// Add a constant qualification. In particular, turn T& into const T&.
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template<class T> struct make_const {typedef const T type;};
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template<class T> struct make_const<T&> {typedef const T& type;};
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// Strip const and reference type annotations. This does *not* strip pointers!
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template<class T> struct basetype {typedef T type;};
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template<class T> struct basetype<const T> {typedef T type;};
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template<class T> struct basetype<T&> {typedef T type;};
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template<class T> struct basetype<const T&> {typedef T type;};
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struct no { int data[2]; };
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typedef int yes;
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template<class T> detail::wrap<T> fakeinstance();
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// use with care
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template<class To, class From>
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struct _is_convertible
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{
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private:
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static yes test(...) {return yes();}
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static no test(To) {return no();}
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public:
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static const bool val = (sizeof(test(fakeinstance<From>().t)) != sizeof(yes));
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};
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// XXX HACK
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template<class To, class A, class B>
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struct _is_convertible<To, A(B)> : false_ { };
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} // traits
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} // flint
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#endif
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