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Diffstat (limited to 'libstdc++/stl/type_traits.h')
| -rw-r--r-- | libstdc++/stl/type_traits.h | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/libstdc++/stl/type_traits.h b/libstdc++/stl/type_traits.h new file mode 100644 index 00000000000..6ca0137709d --- /dev/null +++ b/libstdc++/stl/type_traits.h @@ -0,0 +1,227 @@ +/* + * + * Copyright (c) 1997 + * Silicon Graphics Computer Systems, Inc. + * + * Permission to use, copy, modify, distribute and sell this software + * and its documentation for any purpose is hereby granted without fee, + * provided that the above copyright notice appear in all copies and + * that both that copyright notice and this permission notice appear + * in supporting documentation. Silicon Graphics makes no + * representations about the suitability of this software for any + * purpose. It is provided "as is" without express or implied warranty. + */ + +#ifndef __TYPE_TRAITS_H +#define __TYPE_TRAITS_H + +#include <stl_config.h> + +/* +This header file provides a framework for allowing compile time dispatch +based on type attributes. This is useful when writing template code. +For example, when making a copy of an array of an unknown type, it helps +to know if the type has a trivial copy constructor or not, to help decide +if a memcpy can be used. + +The class template __type_traits provides a series of typedefs each of +which is either __true_type or __false_type. The argument to +__type_traits can be any type. The typedefs within this template will +attain their correct values by one of these means: + 1. The general instantiation contain conservative values which work + for all types. + 2. Specializations may be declared to make distinctions between types. + 3. Some compilers (such as the Silicon Graphics N32 and N64 compilers) + will automatically provide the appropriate specializations for all + types. + +EXAMPLE: + +//Copy an array of elements which have non-trivial copy constructors +template <class T> void copy(T* source,T* destination,int n,__false_type); +//Copy an array of elements which have trivial copy constructors. Use memcpy. +template <class T> void copy(T* source,T* destination,int n,__true_type); + +//Copy an array of any type by using the most efficient copy mechanism +template <class T> inline void copy(T* source,T* destination,int n) { + copy(source,destination,n,__type_traits<T>::has_trivial_copy_constructor()); +} +*/ + + +struct __true_type { +}; + +struct __false_type { +}; + +template <class type> +struct __type_traits { + typedef __true_type this_dummy_member_must_be_first; + /* Do not remove this member. It informs a compiler which + automatically specializes __type_traits that this + __type_traits template is special. It just makes sure that + things work if an implementation is using a template + called __type_traits for something unrelated. */ + + /* The following restrictions should be observed for the sake of + compilers which automatically produce type specific specializations + of this class: + - You may reorder the members below if you wish + - You may remove any of the members below if you wish + - You must not rename members without making the corresponding + name change in the compiler + - Members you add will be treated like regular members unless + you add the appropriate support in the compiler. */ + + + typedef __false_type has_trivial_default_constructor; + typedef __false_type has_trivial_copy_constructor; + typedef __false_type has_trivial_assignment_operator; + typedef __false_type has_trivial_destructor; + typedef __false_type is_POD_type; +}; + + + +// Provide some specializations. This is harmless for compilers that +// have built-in __types_traits support, and essential for compilers +// that don't. + +struct __type_traits<char> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<signed char> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<unsigned char> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<short> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<unsigned short> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<int> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<unsigned int> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<long> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<unsigned long> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<float> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<double> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<long double> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +#ifdef __STL_CLASS_PARTIAL_SPECIALIZATION + +template <class T> +struct __type_traits<T*> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +#else /* __STL_CLASS_PARTIAL_SPECIALIZATION */ + +struct __type_traits<char*> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<signed char*> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +struct __type_traits<unsigned char*> { + typedef __true_type has_trivial_default_constructor; + typedef __true_type has_trivial_copy_constructor; + typedef __true_type has_trivial_assignment_operator; + typedef __true_type has_trivial_destructor; + typedef __true_type is_POD_type; +}; + +#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */ + + +#endif /* __TYPE_TRAITS_H */ |