/usr/include/boost/multi_index/identity.hpp is in libboost1.46-dev 1.46.1-7ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 | /* Copyright 2003-2008 Joaquin M Lopez Munoz.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* See http://www.boost.org/libs/multi_index for library home page.
*/
#ifndef BOOST_MULTI_INDEX_IDENTITY_HPP
#define BOOST_MULTI_INDEX_IDENTITY_HPP
#if defined(_MSC_VER)&&(_MSC_VER>=1200)
#pragma once
#endif
#include <boost/config.hpp>
#include <boost/mpl/if.hpp>
#include <boost/multi_index/identity_fwd.hpp>
#include <boost/type_traits/is_const.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/utility/enable_if.hpp>
#if !defined(BOOST_NO_SFINAE)
#include <boost/type_traits/is_convertible.hpp>
#endif
namespace boost{
template<class Type> class reference_wrapper; /* fwd decl. */
namespace multi_index{
namespace detail{
/* identity is a do-nothing key extractor that returns the [const] Type&
* object passed.
* Additionally, identity is overloaded to support referece_wrappers
* of Type and "chained pointers" to Type's. By chained pointer to Type we
* mean a type P such that, given a p of type P
* *...n...*x is convertible to Type&, for some n>=1.
* Examples of chained pointers are raw and smart pointers, iterators and
* arbitrary combinations of these (vg. Type** or auto_ptr<Type*>.)
*/
/* NB. Some overloads of operator() have an extra dummy parameter int=0.
* This disambiguator serves several purposes:
* - Without it, MSVC++ 6.0 incorrectly regards some overloads as
* specializations of a previous member function template.
* - MSVC++ 6.0/7.0 seem to incorrectly treat some different memfuns
* as if they have the same signature.
* - If remove_const is broken due to lack of PTS, int=0 avoids the
* declaration of memfuns with identical signature.
*/
template<typename Type>
struct const_identity_base
{
typedef Type result_type;
template<typename ChainedPtr>
#if !defined(BOOST_NO_SFINAE)
typename disable_if<is_convertible<const ChainedPtr&,Type&>,Type&>::type
#else
Type&
#endif
operator()(const ChainedPtr& x)const
{
return operator()(*x);
}
Type& operator()(Type& x)const
{
return x;
}
Type& operator()(const reference_wrapper<Type>& x)const
{
return x.get();
}
Type& operator()(
const reference_wrapper<typename remove_const<Type>::type>& x,int=0)const
{
return x.get();
}
};
template<typename Type>
struct non_const_identity_base
{
typedef Type result_type;
/* templatized for pointer-like types */
template<typename ChainedPtr>
#if !defined(BOOST_NO_SFINAE)
typename disable_if<
is_convertible<const ChainedPtr&,const Type&>,Type&>::type
#else
Type&
#endif
operator()(const ChainedPtr& x)const
{
return operator()(*x);
}
const Type& operator()(const Type& x,int=0)const
{
return x;
}
Type& operator()(Type& x)const
{
return x;
}
const Type& operator()(const reference_wrapper<const Type>& x,int=0)const
{
return x.get();
}
Type& operator()(const reference_wrapper<Type>& x)const
{
return x.get();
}
};
} /* namespace multi_index::detail */
template<class Type>
struct identity:
mpl::if_c<
is_const<Type>::value,
detail::const_identity_base<Type>,detail::non_const_identity_base<Type>
>::type
{
};
} /* namespace multi_index */
} /* namespace boost */
#endif
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