--- /dev/null
+// Custom pointer adapter and sample storage policies
+
+// Copyright (C) 2008, 2009 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/**
+ * @file ext/pointer.h
+ * @author Bob Walters
+ *
+ * Provides reusable _Pointer_adapter for assisting in the development of
+ * custom pointer types that can be used with the standard containers via
+ * the allocator::pointer and allocator::const_pointer typedefs.
+ */
+
+#ifndef _POINTER_H
+#define _POINTER_H 1
+
+#include <iosfwd>
+#include <bits/stl_iterator_base_types.h>
+#include <ext/cast.h>
+#include <ext/type_traits.h>
+
+_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
+
+ /**
+ * @brief A storage policy for use with _Pointer_adapter<> which yields a
+ * standard pointer.
+ *
+ * A _Storage_policy is required to provide 4 things:
+ * 1) A get() API for returning the stored pointer value.
+ * 2) An set() API for storing a pointer value.
+ * 3) An element_type typedef to define the type this points to.
+ * 4) An operator<() to support pointer comparison.
+ * 5) An operator==() to support pointer comparison.
+ */
+ template<typename _Tp>
+ class _Std_pointer_impl
+ {
+ public:
+ // the type this pointer points to.
+ typedef _Tp element_type;
+
+ // A method to fetch the pointer value as a standard T* value;
+ inline _Tp*
+ get() const
+ { return _M_value; }
+
+ // A method to set the pointer value, from a standard T* value;
+ inline void
+ set(element_type* __arg)
+ { _M_value = __arg; }
+
+ // Comparison of pointers
+ inline bool
+ operator<(const _Std_pointer_impl& __rarg) const
+ { return (_M_value < __rarg._M_value); }
+
+ inline bool
+ operator==(const _Std_pointer_impl& __rarg) const
+ { return (_M_value == __rarg._M_value); }
+
+ private:
+ element_type* _M_value;
+ };
+
+ /**
+ * @brief A storage policy for use with _Pointer_adapter<> which stores
+ * the pointer's address as an offset value which is relative to
+ * its own address.
+ *
+ * This is intended for pointers
+ * within shared memory regions which might be mapped at different
+ * addresses by different processes. For null pointers, a value of 1 is
+ * used. (0 is legitimate sometimes for nodes in circularly linked lists)
+ * This value was chosen as the least likely to generate an incorrect null,
+ * As there is no reason why any normal pointer would point 1 byte into
+ * its own pointer address.
+ */
+ template<typename _Tp>
+ class _Relative_pointer_impl
+ {
+ public:
+ typedef _Tp element_type;
+
+ _Tp*
+ get() const
+ {
+ if (_M_diff == 1)
+ return 0;
+ else
+ return reinterpret_cast<_Tp*>(reinterpret_cast<_UIntPtrType>(this)
+ + _M_diff);
+ }
+
+ void
+ set(_Tp* __arg)
+ {
+ if (!__arg)
+ _M_diff = 1;
+ else
+ _M_diff = reinterpret_cast<_UIntPtrType>(__arg)
+ - reinterpret_cast<_UIntPtrType>(this);
+ }
+
+ // Comparison of pointers
+ inline bool
+ operator<(const _Relative_pointer_impl& __rarg) const
+ { return (reinterpret_cast<_UIntPtrType>(this->get())
+ < reinterpret_cast<_UIntPtrType>(__rarg.get())); }
+
+ inline bool
+ operator==(const _Relative_pointer_impl& __rarg) const
+ { return (reinterpret_cast<_UIntPtrType>(this->get())
+ == reinterpret_cast<_UIntPtrType>(__rarg.get())); }
+
+ private:
+ typedef __gnu_cxx::__conditional_type<
+ (sizeof(unsigned long) >= sizeof(void*)),
+ unsigned long, unsigned long long>::__type _UIntPtrType;
+ _UIntPtrType _M_diff;
+ };
+
+ /**
+ * Relative_pointer_impl needs a specialization for const T because of
+ * the casting done during pointer arithmetic.
+ */
+ template<typename _Tp>
+ class _Relative_pointer_impl<const _Tp>
+ {
+ public:
+ typedef const _Tp element_type;
+
+ const _Tp*
+ get() const
+ {
+ if (_M_diff == 1)
+ return 0;
+ else
+ return reinterpret_cast<const _Tp*>
+ (reinterpret_cast<_UIntPtrType>(this) + _M_diff);
+ }
+
+ void
+ set(const _Tp* __arg)
+ {
+ if (!__arg)
+ _M_diff = 1;
+ else
+ _M_diff = reinterpret_cast<_UIntPtrType>(__arg)
+ - reinterpret_cast<_UIntPtrType>(this);
+ }
+
+ // Comparison of pointers
+ inline bool
+ operator<(const _Relative_pointer_impl& __rarg) const
+ { return (reinterpret_cast<_UIntPtrType>(this->get())
+ < reinterpret_cast<_UIntPtrType>(__rarg.get())); }
+
+ inline bool
+ operator==(const _Relative_pointer_impl& __rarg) const
+ { return (reinterpret_cast<_UIntPtrType>(this->get())
+ == reinterpret_cast<_UIntPtrType>(__rarg.get())); }
+
+ private:
+ typedef __gnu_cxx::__conditional_type
+ <(sizeof(unsigned long) >= sizeof(void*)),
+ unsigned long, unsigned long long>::__type _UIntPtrType;
+ _UIntPtrType _M_diff;
+ };
+
+ /**
+ * The specialization on this type helps resolve the problem of
+ * reference to void, and eliminates the need to specialize _Pointer_adapter
+ * for cases of void*, const void*, and so on.
+ */
+ struct _Invalid_type { };
+
+ template<typename _Tp>
+ struct _Reference_type
+ { typedef _Tp& reference; };
+
+ template<>
+ struct _Reference_type<void>
+ { typedef _Invalid_type& reference; };
+
+ template<>
+ struct _Reference_type<const void>
+ { typedef const _Invalid_type& reference; };
+
+ template<>
+ struct _Reference_type<volatile void>
+ { typedef volatile _Invalid_type& reference; };
+
+ template<>
+ struct _Reference_type<volatile const void>
+ { typedef const volatile _Invalid_type& reference; };
+
+ /**
+ * This structure accomodates the way in which std::iterator_traits<>
+ * is normally specialized for const T*, so that value_type is still T.
+ */
+ template<typename _Tp>
+ struct _Unqualified_type
+ { typedef _Tp type; };
+
+ template<typename _Tp>
+ struct _Unqualified_type<const _Tp>
+ { typedef _Tp type; };
+
+ template<typename _Tp>
+ struct _Unqualified_type<volatile _Tp>
+ { typedef volatile _Tp type; };
+
+ template<typename _Tp>
+ struct _Unqualified_type<volatile const _Tp>
+ { typedef volatile _Tp type; };
+
+ /**
+ * The following provides an 'alternative pointer' that works with the
+ * containers when specified as the pointer typedef of the allocator.
+ *
+ * The pointer type used with the containers doesn't have to be this class,
+ * but it must support the implicit conversions, pointer arithmetic,
+ * comparison operators, etc. that are supported by this class, and avoid
+ * raising compile-time ambiguities. Because creating a working pointer can
+ * be challenging, this pointer template was designed to wrapper an
+ * easier storage policy type, so that it becomes reusable for creating
+ * other pointer types.
+ *
+ * A key point of this class is also that it allows container writers to
+ * 'assume' Alocator::pointer is a typedef for a normal pointer. This class
+ * supports most of the conventions of a true pointer, and can, for instance
+ * handle implicit conversion to const and base class pointer types. The
+ * only impositions on container writers to support extended pointers are:
+ * 1) use the Allocator::pointer typedef appropriately for pointer types.
+ * 2) if you need pointer casting, use the __pointer_cast<> functions
+ * from ext/cast.h. This allows pointer cast operations to be overloaded
+ * is necessary by custom pointers.
+ *
+ * Note: The const qualifier works with this pointer adapter as follows:
+ *
+ * _Tp* == _Pointer_adapter<_Std_pointer_impl<_Tp> >;
+ * const _Tp* == _Pointer_adapter<_Std_pointer_impl<const _Tp> >;
+ * _Tp* const == const _Pointer_adapter<_Std_pointer_impl<_Tp> >;
+ * const _Tp* const == const _Pointer_adapter<_Std_pointer_impl<const _Tp> >;
+ */
+ template<typename _Storage_policy>
+ class _Pointer_adapter : public _Storage_policy
+ {
+ public:
+ typedef typename _Storage_policy::element_type element_type;
+
+ // These are needed for iterator_traits
+ typedef std::random_access_iterator_tag iterator_category;
+ typedef typename _Unqualified_type<element_type>::type value_type;
+ typedef std::ptrdiff_t difference_type;
+ typedef _Pointer_adapter pointer;
+ typedef typename _Reference_type<element_type>::reference reference;
+
+ // Reminder: 'const' methods mean that the method is valid when the
+ // pointer is immutable, and has nothing to do with whether the
+ // 'pointee' is const.
+
+ // Default Constructor (Convert from element_type*)
+ _Pointer_adapter(element_type* __arg = 0)
+ { _Storage_policy::set(__arg); }
+
+ // Copy constructor from _Pointer_adapter of same type.
+ _Pointer_adapter(const _Pointer_adapter& __arg)
+ { _Storage_policy::set(__arg.get()); }
+
+ // Convert from _Up* if conversion to element_type* is valid.
+ template<typename _Up>
+ _Pointer_adapter(_Up* __arg)
+ { _Storage_policy::set(__arg); }
+
+ // Conversion from another _Pointer_adapter if _Up if static cast is
+ // valid.
+ template<typename _Up>
+ _Pointer_adapter(const _Pointer_adapter<_Up>& __arg)
+ { _Storage_policy::set(__arg.get()); }
+
+ // Destructor
+ ~_Pointer_adapter() { }
+
+ // Assignment operator
+ _Pointer_adapter&
+ operator=(const _Pointer_adapter& __arg)
+ {
+ _Storage_policy::set(__arg.get());
+ return *this;
+ }
+
+ template<typename _Up>
+ _Pointer_adapter&
+ operator=(const _Pointer_adapter<_Up>& __arg)
+ {
+ _Storage_policy::set(__arg.get());
+ return *this;
+ }
+
+ template<typename _Up>
+ _Pointer_adapter&
+ operator=(_Up* __arg)
+ {
+ _Storage_policy::set(__arg);
+ return *this;
+ }
+
+ // Operator*, returns element_type&
+ inline reference
+ operator*() const
+ { return *(_Storage_policy::get()); }
+
+ // Operator->, returns element_type*
+ inline element_type*
+ operator->() const
+ { return _Storage_policy::get(); }
+
+ // Operator[], returns a element_type& to the item at that loc.
+ inline reference
+ operator[](std::ptrdiff_t __index) const
+ { return _Storage_policy::get()[__index]; }
+
+ // To allow implicit conversion to "bool", for "if (ptr)..."
+ private:
+ typedef element_type*(_Pointer_adapter::*__unspecified_bool_type)() const;
+
+ public:
+ operator __unspecified_bool_type() const
+ {
+ return _Storage_policy::get() == 0 ? 0 :
+ &_Pointer_adapter::operator->;
+ }
+
+ // ! operator (for: if (!ptr)...)
+ inline bool
+ operator!() const
+ { return (_Storage_policy::get() == 0); }
+
+ // Pointer differences
+ inline friend std::ptrdiff_t
+ operator-(const _Pointer_adapter& __lhs, element_type* __rhs)
+ { return (__lhs.get() - __rhs); }
+
+ inline friend std::ptrdiff_t
+ operator-(element_type* __lhs, const _Pointer_adapter& __rhs)
+ { return (__lhs - __rhs.get()); }
+
+ template<typename _Up>
+ inline friend std::ptrdiff_t
+ operator-(const _Pointer_adapter& __lhs, _Up* __rhs)
+ { return (__lhs.get() - __rhs); }
+
+ template<typename _Up>
+ inline friend std::ptrdiff_t
+ operator-(_Up* __lhs, const _Pointer_adapter& __rhs)
+ { return (__lhs - __rhs.get()); }
+
+ template<typename _Up>
+ inline std::ptrdiff_t
+ operator-(const _Pointer_adapter<_Up>& __rhs) const
+ { return (_Storage_policy::get() - __rhs.get()); }
+
+ // Pointer math
+ // Note: There is a reason for all this overloading based on different
+ // integer types. In some libstdc++-v3 test cases, a templated
+ // operator+ is declared which can match any types. This operator
+ // tends to "steal" the recognition of _Pointer_adapter's own operator+
+ // unless the integer type matches perfectly.
+
+#define _CXX_POINTER_ARITH_OPERATOR_SET(INT_TYPE) \
+ inline friend _Pointer_adapter \
+ operator+(const _Pointer_adapter& __lhs, INT_TYPE __offset) \
+ { return _Pointer_adapter(__lhs.get() + __offset); } \
+\
+ inline friend _Pointer_adapter \
+ operator+(INT_TYPE __offset, const _Pointer_adapter& __rhs) \
+ { return _Pointer_adapter(__rhs.get() + __offset); } \
+\
+ inline friend _Pointer_adapter \
+ operator-(const _Pointer_adapter& __lhs, INT_TYPE __offset) \
+ { return _Pointer_adapter(__lhs.get() - __offset); } \
+\
+ inline _Pointer_adapter& \
+ operator+=(INT_TYPE __offset) \
+ { \
+ _Storage_policy::set(_Storage_policy::get() + __offset); \
+ return *this; \
+ } \
+\
+ inline _Pointer_adapter& \
+ operator-=(INT_TYPE __offset) \
+ { \
+ _Storage_policy::set(_Storage_policy::get() - __offset); \
+ return *this; \
+ } \
+// END of _CXX_POINTER_ARITH_OPERATOR_SET macro
+
+ // Expand into the various pointer arithmatic operators needed.
+ _CXX_POINTER_ARITH_OPERATOR_SET(short);
+ _CXX_POINTER_ARITH_OPERATOR_SET(unsigned short);
+ _CXX_POINTER_ARITH_OPERATOR_SET(int);
+ _CXX_POINTER_ARITH_OPERATOR_SET(unsigned int);
+ _CXX_POINTER_ARITH_OPERATOR_SET(long);
+ _CXX_POINTER_ARITH_OPERATOR_SET(unsigned long);
+
+ // Mathematical Manipulators
+ inline _Pointer_adapter&
+ operator++()
+ {
+ _Storage_policy::set(_Storage_policy::get() + 1);
+ return *this;
+ }
+
+ inline _Pointer_adapter
+ operator++(int __unused)
+ {
+ _Pointer_adapter tmp(*this);
+ _Storage_policy::set(_Storage_policy::get() + 1);
+ return tmp;
+ }
+
+ inline _Pointer_adapter&
+ operator--()
+ {
+ _Storage_policy::set(_Storage_policy::get() - 1);
+ return *this;
+ }
+
+ inline _Pointer_adapter
+ operator--(int)
+ {
+ _Pointer_adapter tmp(*this);
+ _Storage_policy::set(_Storage_policy::get() - 1);
+ return tmp;
+ }
+
+ }; // class _Pointer_adapter
+
+
+#define _GCC_CXX_POINTER_COMPARISON_OPERATION_SET(OPERATOR,BLANK) \
+ template<typename _Tp1, typename _Tp2> \
+ inline bool \
+ operator OPERATOR##BLANK (const _Pointer_adapter<_Tp1>& __lhs, _Tp2 __rhs) \
+ { return __lhs.get() OPERATOR##BLANK __rhs; } \
+\
+ template<typename _Tp1, typename _Tp2> \
+ inline bool \
+ operator OPERATOR##BLANK (_Tp1 __lhs, const _Pointer_adapter<_Tp2>& __rhs) \
+ { return __lhs OPERATOR##BLANK __rhs.get(); } \
+\
+ template<typename _Tp1, typename _Tp2> \
+ inline bool \
+ operator OPERATOR##BLANK (const _Pointer_adapter<_Tp1>& __lhs, \
+ const _Pointer_adapter<_Tp2>& __rhs) \
+ { return __lhs.get() OPERATOR##BLANK __rhs.get(); } \
+\
+// End GCC_CXX_POINTER_COMPARISON_OPERATION_SET Macro
+
+ // Expand into the various comparison operators needed.
+ _GCC_CXX_POINTER_COMPARISON_OPERATION_SET(==,);
+ _GCC_CXX_POINTER_COMPARISON_OPERATION_SET(!=,);
+ _GCC_CXX_POINTER_COMPARISON_OPERATION_SET(<,);
+ _GCC_CXX_POINTER_COMPARISON_OPERATION_SET(<=,);
+ _GCC_CXX_POINTER_COMPARISON_OPERATION_SET(>,);
+ _GCC_CXX_POINTER_COMPARISON_OPERATION_SET(>=,);
+
+ // These are here for expressions like "ptr == 0", "ptr != 0"
+ template<typename _Tp>
+ inline bool
+ operator==(const _Pointer_adapter<_Tp>& __lhs, int __rhs)
+ { return __lhs.get() == reinterpret_cast<void*>(__rhs); }
+
+ template<typename _Tp>
+ inline bool
+ operator==(int __lhs, const _Pointer_adapter<_Tp>& __rhs)
+ { return __rhs.get() == reinterpret_cast<void*>(__lhs); }
+
+ template<typename _Tp>
+ inline bool
+ operator!=(const _Pointer_adapter<_Tp>& __lhs, int __rhs)
+ { return __lhs.get() != reinterpret_cast<void*>(__rhs); }
+
+ template<typename _Tp>
+ inline bool
+ operator!=(int __lhs, const _Pointer_adapter<_Tp>& __rhs)
+ { return __rhs.get() != reinterpret_cast<void*>(__lhs); }
+
+ /**
+ * Comparison operators for _Pointer_adapter defer to the base class'es
+ * comparison operators, when possible.
+ */
+ template<typename _Tp>
+ inline bool
+ operator==(const _Pointer_adapter<_Tp>& __lhs,
+ const _Pointer_adapter<_Tp>& __rhs)
+ { return __lhs._Tp::operator==(__rhs); }
+
+ template<typename _Tp>
+ inline bool
+ operator<=(const _Pointer_adapter<_Tp>& __lhs,
+ const _Pointer_adapter<_Tp>& __rhs)
+ { return __lhs._Tp::operator<(__rhs) || __lhs._Tp::operator==(__rhs); }
+
+ template<typename _Tp>
+ inline bool
+ operator!=(const _Pointer_adapter<_Tp>& __lhs,
+ const _Pointer_adapter<_Tp>& __rhs)
+ { return !(__lhs._Tp::operator==(__rhs)); }
+
+ template<typename _Tp>
+ inline bool
+ operator>(const _Pointer_adapter<_Tp>& __lhs,
+ const _Pointer_adapter<_Tp>& __rhs)
+ { return !(__lhs._Tp::operator<(__rhs) || __lhs._Tp::operator==(__rhs)); }
+
+ template<typename _Tp>
+ inline bool
+ operator>=(const _Pointer_adapter<_Tp>& __lhs,
+ const _Pointer_adapter<_Tp>& __rhs)
+ { return !(__lhs._Tp::operator<(__rhs)); }
+
+ template<typename _CharT, typename _Traits, typename _StoreT>
+ inline std::basic_ostream<_CharT, _Traits>&
+ operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+ const _Pointer_adapter<_StoreT>& __p)
+ { return (__os << __p.get()); }
+
+_GLIBCXX_END_NAMESPACE
+
+#endif // _POINTER_H
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