stl_iterator_base_types.h

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00001 // Types used in iterator implementation -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
00004 // Free Software Foundation, Inc.
00005 //
00006 // This file is part of the GNU ISO C++ Library.  This library is free
00007 // software; you can redistribute it and/or modify it under the
00008 // terms of the GNU General Public License as published by the
00009 // Free Software Foundation; either version 3, or (at your option)
00010 // any later version.
00011 
00012 // This library is distributed in the hope that it will be useful,
00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015 // GNU General Public License for more details.
00016 
00017 // Under Section 7 of GPL version 3, you are granted additional
00018 // permissions described in the GCC Runtime Library Exception, version
00019 // 3.1, as published by the Free Software Foundation.
00020 
00021 // You should have received a copy of the GNU General Public License and
00022 // a copy of the GCC Runtime Library Exception along with this program;
00023 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00024 // <http://www.gnu.org/licenses/>.
00025 
00026 /*
00027  *
00028  * Copyright (c) 1994
00029  * Hewlett-Packard Company
00030  *
00031  * Permission to use, copy, modify, distribute and sell this software
00032  * and its documentation for any purpose is hereby granted without fee,
00033  * provided that the above copyright notice appear in all copies and
00034  * that both that copyright notice and this permission notice appear
00035  * in supporting documentation.  Hewlett-Packard Company makes no
00036  * representations about the suitability of this software for any
00037  * purpose.  It is provided "as is" without express or implied warranty.
00038  *
00039  *
00040  * Copyright (c) 1996-1998
00041  * Silicon Graphics Computer Systems, Inc.
00042  *
00043  * Permission to use, copy, modify, distribute and sell this software
00044  * and its documentation for any purpose is hereby granted without fee,
00045  * provided that the above copyright notice appear in all copies and
00046  * that both that copyright notice and this permission notice appear
00047  * in supporting documentation.  Silicon Graphics makes no
00048  * representations about the suitability of this software for any
00049  * purpose.  It is provided "as is" without express or implied warranty.
00050  */
00051 
00052 /** @file stl_iterator_base_types.h
00053  *  This is an internal header file, included by other library headers.
00054  *  You should not attempt to use it directly.
00055  *
00056  *  This file contains all of the general iterator-related utility types,
00057  *  such as iterator_traits and struct iterator.
00058  */
00059 
00060 #ifndef _STL_ITERATOR_BASE_TYPES_H
00061 #define _STL_ITERATOR_BASE_TYPES_H 1
00062 
00063 #pragma GCC system_header
00064 
00065 #include <bits/c++config.h>
00066 
00067 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00068 # include <type_traits>  // For _GLIBCXX_HAS_NESTED_TYPE
00069 #endif
00070 
00071 _GLIBCXX_BEGIN_NAMESPACE(std)
00072 
00073   /**
00074    *  @defgroup iterators Iterators
00075    *  Abstractions for uniform iterating through various underlying types.
00076   */
00077   //@{ 
00078 
00079   /**
00080    *  @defgroup iterator_tags Iterator Tags
00081    *  These are empty types, used to distinguish different iterators.  The
00082    *  distinction is not made by what they contain, but simply by what they
00083    *  are.  Different underlying algorithms can then be used based on the
00084    *  different operations supported by different iterator types.
00085   */
00086   //@{ 
00087   ///  Marking input iterators.
00088   struct input_iterator_tag { };
00089 
00090   ///  Marking output iterators.
00091   struct output_iterator_tag { };
00092 
00093   /// Forward iterators support a superset of input iterator operations.
00094   struct forward_iterator_tag : public input_iterator_tag { };
00095 
00096   /// Bidirectional iterators support a superset of forward iterator
00097   /// operations.
00098   struct bidirectional_iterator_tag : public forward_iterator_tag { };
00099 
00100   /// Random-access iterators support a superset of bidirectional
00101   /// iterator operations.
00102   struct random_access_iterator_tag : public bidirectional_iterator_tag { };
00103   //@}
00104 
00105   /**
00106    *  @brief  Common %iterator class.
00107    *
00108    *  This class does nothing but define nested typedefs.  %Iterator classes
00109    *  can inherit from this class to save some work.  The typedefs are then
00110    *  used in specializations and overloading.
00111    *
00112    *  In particular, there are no default implementations of requirements
00113    *  such as @c operator++ and the like.  (How could there be?)
00114   */
00115   template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
00116            typename _Pointer = _Tp*, typename _Reference = _Tp&>
00117     struct iterator
00118     {
00119       /// One of the @link iterator_tags tag types@endlink.
00120       typedef _Category  iterator_category;
00121       /// The type "pointed to" by the iterator.
00122       typedef _Tp        value_type;
00123       /// Distance between iterators is represented as this type.
00124       typedef _Distance  difference_type;
00125       /// This type represents a pointer-to-value_type.
00126       typedef _Pointer   pointer;
00127       /// This type represents a reference-to-value_type.
00128       typedef _Reference reference;
00129     };
00130 
00131   /**
00132    *  @brief  Traits class for iterators.
00133    *
00134    *  This class does nothing but define nested typedefs.  The general
00135    *  version simply @a forwards the nested typedefs from the Iterator
00136    *  argument.  Specialized versions for pointers and pointers-to-const
00137    *  provide tighter, more correct semantics.
00138   */
00139 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00140 
00141 _GLIBCXX_HAS_NESTED_TYPE(iterator_category)
00142 
00143   template<typename _Iterator,
00144        bool = __has_iterator_category<_Iterator>::value>
00145     struct __iterator_traits { };
00146 
00147   template<typename _Iterator>
00148     struct __iterator_traits<_Iterator, true>
00149     {
00150       typedef typename _Iterator::iterator_category iterator_category;
00151       typedef typename _Iterator::value_type        value_type;
00152       typedef typename _Iterator::difference_type   difference_type;
00153       typedef typename _Iterator::pointer           pointer;
00154       typedef typename _Iterator::reference         reference;
00155     };
00156 
00157   template<typename _Iterator>
00158     struct iterator_traits
00159     : public __iterator_traits<_Iterator> { };
00160 #else
00161   template<typename _Iterator>
00162     struct iterator_traits
00163     {
00164       typedef typename _Iterator::iterator_category iterator_category;
00165       typedef typename _Iterator::value_type        value_type;
00166       typedef typename _Iterator::difference_type   difference_type;
00167       typedef typename _Iterator::pointer           pointer;
00168       typedef typename _Iterator::reference         reference;
00169     };
00170 #endif
00171 
00172   /// Partial specialization for pointer types.
00173   template<typename _Tp>
00174     struct iterator_traits<_Tp*>
00175     {
00176       typedef random_access_iterator_tag iterator_category;
00177       typedef _Tp                         value_type;
00178       typedef ptrdiff_t                   difference_type;
00179       typedef _Tp*                        pointer;
00180       typedef _Tp&                        reference;
00181     };
00182 
00183   /// Partial specialization for const pointer types.
00184   template<typename _Tp>
00185     struct iterator_traits<const _Tp*>
00186     {
00187       typedef random_access_iterator_tag iterator_category;
00188       typedef _Tp                         value_type;
00189       typedef ptrdiff_t                   difference_type;
00190       typedef const _Tp*                  pointer;
00191       typedef const _Tp&                  reference;
00192     };
00193 
00194   /**
00195    *  This function is not a part of the C++ standard but is syntactic
00196    *  sugar for internal library use only.
00197   */
00198   template<typename _Iter>
00199     inline typename iterator_traits<_Iter>::iterator_category
00200     __iterator_category(const _Iter&)
00201     { return typename iterator_traits<_Iter>::iterator_category(); }
00202 
00203   //@}
00204 
00205   // If _Iterator has a base returns it otherwise _Iterator is returned
00206   // untouched
00207   template<typename _Iterator, bool _HasBase>
00208     struct _Iter_base
00209     {
00210       typedef _Iterator iterator_type;
00211       static iterator_type _S_base(_Iterator __it)
00212       { return __it; }
00213     };
00214 
00215   template<typename _Iterator>
00216     struct _Iter_base<_Iterator, true>
00217     {
00218       typedef typename _Iterator::iterator_type iterator_type;
00219       static iterator_type _S_base(_Iterator __it)
00220       { return __it.base(); }
00221     };
00222 
00223 _GLIBCXX_END_NAMESPACE
00224 
00225 #endif /* _STL_ITERATOR_BASE_TYPES_H */
00226