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