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// (C) Copyright David Abrahams 2002.
// (C) Copyright Jeremy Siek 2002.
// (C) Copyright Thomas Witt 2002.
// 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)
#ifndef BOOST_ITERATOR_FACADE_23022003THW_HPP
#define BOOST_ITERATOR_FACADE_23022003THW_HPP
#include <boost/iterator.hpp>
#include <boost/iterator/interoperable.hpp>
#include <boost/iterator/iterator_traits.hpp>
#include <boost/iterator/detail/facade_iterator_category.hpp>
#include <boost/iterator/detail/enable_if.hpp>
#include <boost/implicit_cast.hpp>
#include <boost/static_assert.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/type_traits/add_const.hpp>
#include <boost/type_traits/add_pointer.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/type_traits/is_convertible.hpp>
#include <boost/type_traits/is_pod.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/or.hpp>
#include <boost/mpl/and.hpp>
#include <boost/mpl/not.hpp>
#include <boost/mpl/always.hpp>
#include <boost/mpl/apply.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/iterator/detail/config_def.hpp> // this goes last
namespace boost
{
// This forward declaration is required for the friend declaration
// in iterator_core_access
template <class I, class V, class TC, class R, class D> class iterator_facade;
namespace detail
{
// A binary metafunction class that always returns bool. VC6
// ICEs on mpl::always<bool>, probably because of the default
// parameters.
struct always_bool2
{
template <class T, class U>
struct apply
{
typedef bool type;
};
};
//
// enable if for use in operator implementation.
//
template <
class Facade1
, class Facade2
, class Return
>
struct enable_if_interoperable
#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
{
typedef typename mpl::if_<
mpl::or_<
is_convertible<Facade1, Facade2>
, is_convertible<Facade2, Facade1>
>
, Return
, int[3]
>::type type;
};
#else
: ::boost::iterators::enable_if<
mpl::or_<
is_convertible<Facade1, Facade2>
, is_convertible<Facade2, Facade1>
>
, Return
>
{};
#endif
//
// Generates associated types for an iterator_facade with the
// given parameters.
//
template <
class ValueParam
, class CategoryOrTraversal
, class Reference
, class Difference
>
struct iterator_facade_types
{
typedef typename facade_iterator_category<
CategoryOrTraversal, ValueParam, Reference
>::type iterator_category;
typedef typename remove_const<ValueParam>::type value_type;
typedef typename mpl::eval_if<
boost::detail::iterator_writability_disabled<ValueParam,Reference>
, add_pointer<const value_type>
, add_pointer<value_type>
>::type pointer;
# if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) \
&& (BOOST_WORKAROUND(_STLPORT_VERSION, BOOST_TESTED_AT(0x452)) \
|| BOOST_WORKAROUND(BOOST_DINKUMWARE_STDLIB, BOOST_TESTED_AT(310))) \
|| BOOST_WORKAROUND(BOOST_RWSTD_VER, BOOST_TESTED_AT(0x20101)) \
|| BOOST_WORKAROUND(BOOST_DINKUMWARE_STDLIB, <= 310)
// To interoperate with some broken library/compiler
// combinations, user-defined iterators must be derived from
// std::iterator. It is possible to implement a standard
// library for broken compilers without this limitation.
# define BOOST_ITERATOR_FACADE_NEEDS_ITERATOR_BASE 1
typedef
iterator<iterator_category, value_type, Difference, pointer, Reference>
base;
# endif
};
// iterators whose dereference operators reference the same value
// for all iterators into the same sequence (like many input
// iterators) need help with their postfix ++: the referenced
// value must be read and stored away before the increment occurs
// so that *a++ yields the originally referenced element and not
// the next one.
template <class Iterator>
class postfix_increment_proxy
{
typedef typename iterator_value<Iterator>::type value_type;
public:
explicit postfix_increment_proxy(Iterator const& x)
: stored_value(*x)
{}
// Returning a mutable reference allows nonsense like
// (*r++).mutate(), but it imposes fewer assumptions about the
// behavior of the value_type. In particular, recall taht
// (*r).mutate() is legal if operator* returns by value.
value_type&
operator*() const
{
return this->stored_value;
}
private:
mutable value_type stored_value;
};
//
// In general, we can't determine that such an iterator isn't
// writable -- we also need to store a copy of the old iterator so
// that it can be written into.
template <class Iterator>
class writable_postfix_increment_proxy
{
typedef typename iterator_value<Iterator>::type value_type;
public:
explicit writable_postfix_increment_proxy(Iterator const& x)
: stored_value(*x)
, stored_iterator(x)
{}
// Dereferencing must return a proxy so that both *r++ = o and
// value_type(*r++) can work. In this case, *r is the same as
// *r++, and the conversion operator below is used to ensure
// readability.
writable_postfix_increment_proxy const&
operator*() const
{
return *this;
}
// Provides readability of *r++
operator value_type&() const
{
return stored_value;
}
// Provides writability of *r++
template <class T>
T const& operator=(T const& x) const
{
*this->stored_iterator = x;
return x;
}
// This overload just in case only non-const objects are writable
template <class T>
T& operator=(T& x) const
{
*this->stored_iterator = x;
return x;
}
// Provides X(r++)
operator Iterator const&() const
{
return stored_iterator;
}
private:
mutable value_type stored_value;
Iterator stored_iterator;
};
# ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
template <class Reference, class Value>
struct is_non_proxy_reference_impl
{
static Reference r;
template <class R>
static typename mpl::if_<
is_convertible<
R const volatile*
, Value const volatile*
>
, char[1]
, char[2]
>::type& helper(R const&);
BOOST_STATIC_CONSTANT(bool, value = sizeof(helper(r)) == 1);
};
template <class Reference, class Value>
struct is_non_proxy_reference
: mpl::bool_<
is_non_proxy_reference_impl<Reference, Value>::value
>
{};
# else
template <class Reference, class Value>
struct is_non_proxy_reference
: is_convertible<
typename remove_reference<Reference>::type
const volatile*
, Value const volatile*
>
{};
# endif
// A metafunction to choose the result type of postfix ++
//
// Because the C++98 input iterator requirements say that *r++ has
// type T (value_type), implementations of some standard
// algorithms like lexicographical_compare may use constructions
// like:
//
// *r++ < *s++
//
// If *r++ returns a proxy (as required if r is writable but not
// multipass), this sort of expression will fail unless the proxy
// supports the operator<. Since there are any number of such
// operations, we're not going to try to support them. Therefore,
// even if r++ returns a proxy, *r++ will only return a proxy if
// *r also returns a proxy.
template <class Iterator, class Value, class Reference, class CategoryOrTraversal>
struct postfix_increment_result
: mpl::eval_if<
mpl::and_<
// A proxy is only needed for readable iterators
is_convertible<Reference,Value const&>
// No multipass iterator can have values that disappear
// before positions can be re-visited
, mpl::not_<
is_convertible<
typename iterator_category_to_traversal<CategoryOrTraversal>::type
, forward_traversal_tag
>
>
>
, mpl::if_<
is_non_proxy_reference<Reference,Value>
, postfix_increment_proxy<Iterator>
, writable_postfix_increment_proxy<Iterator>
>
, mpl::identity<Iterator>
>
{};
// operator->() needs special support for input iterators to strictly meet the
// standard's requirements. If *i is not a reference type, we must still
// produce a lvalue to which a pointer can be formed. We do that by
// returning an instantiation of this special proxy class template.
template <class T>
struct operator_arrow_proxy
{
operator_arrow_proxy(T const* px) : m_value(*px) {}
T* operator->() const { return &m_value; }
// This function is needed for MWCW and BCC, which won't call operator->
// again automatically per 13.3.1.2 para 8
operator T*() const { return &m_value; }
mutable T m_value;
};
// A metafunction that gets the result type for operator->. Also
// has a static function make() which builds the result from a
// Reference
template <class ValueType, class Reference, class Pointer>
struct operator_arrow_result
{
// CWPro8.3 won't accept "operator_arrow_result::type", and we
// need that type below, so metafunction forwarding would be a
// losing proposition here.
typedef typename mpl::if_<
is_reference<Reference>
, Pointer
, operator_arrow_proxy<ValueType>
>::type type;
static type make(Reference x)
{
return implicit_cast<type>(&x);
}
};
# if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
// Deal with ETI
template<>
struct operator_arrow_result<int, int, int>
{
typedef int type;
};
# endif
// A proxy return type for operator[], needed to deal with
// iterators that may invalidate referents upon destruction.
// Consider the temporary iterator in *(a + n)
template <class Iterator>
class operator_brackets_proxy
{
// Iterator is actually an iterator_facade, so we do not have to
// go through iterator_traits to access the traits.
typedef typename Iterator::reference reference;
typedef typename Iterator::value_type value_type;
public:
operator_brackets_proxy(Iterator const& iter)
: m_iter(iter)
{}
operator reference() const
{
return *m_iter;
}
operator_brackets_proxy& operator=(value_type const& val)
{
*m_iter = val;
return *this;
}
private:
Iterator m_iter;
};
// A metafunction that determines whether operator[] must return a
// proxy, or whether it can simply return a copy of the value_type.
template <class ValueType, class Reference>
struct use_operator_brackets_proxy
: mpl::not_<
mpl::and_<
// Really we want an is_copy_constructible trait here,
// but is_POD will have to suffice in the meantime.
boost::is_POD<ValueType>
, iterator_writability_disabled<ValueType,Reference>
>
>
{};
template <class Iterator, class Value, class Reference>
struct operator_brackets_result
{
typedef typename mpl::if_<
use_operator_brackets_proxy<Value,Reference>
, operator_brackets_proxy<Iterator>
, Value
>::type type;
};
template <class Iterator>
operator_brackets_proxy<Iterator> make_operator_brackets_result(Iterator const& iter, mpl::true_)
{
return operator_brackets_proxy<Iterator>(iter);
}
template <class Iterator>
typename Iterator::value_type make_operator_brackets_result(Iterator const& iter, mpl::false_)
{
return *iter;
}
struct choose_difference_type
{
template <class I1, class I2>
struct apply
:
# ifdef BOOST_NO_ONE_WAY_ITERATOR_INTEROP
iterator_difference<I1>
# elif BOOST_WORKAROUND(BOOST_MSVC, < 1300)
mpl::if_<
is_convertible<I2,I1>
, typename I1::difference_type
, typename I2::difference_type
>
# else
mpl::eval_if<
is_convertible<I2,I1>
, iterator_difference<I1>
, iterator_difference<I2>
>
# endif
{};
};
} // namespace detail
// Macros which describe the declarations of binary operators
# ifdef BOOST_NO_STRICT_ITERATOR_INTEROPERABILITY
# define BOOST_ITERATOR_FACADE_INTEROP_HEAD(prefix, op, result_type) \
template < \
class Derived1, class V1, class TC1, class Reference1, class Difference1 \
, class Derived2, class V2, class TC2, class Reference2, class Difference2 \
> \
prefix typename mpl::apply2<result_type,Derived1,Derived2>::type \
operator op( \
iterator_facade<Derived1, V1, TC1, Reference1, Difference1> const& lhs \
, iterator_facade<Derived2, V2, TC2, Reference2, Difference2> const& rhs)
# else
# define BOOST_ITERATOR_FACADE_INTEROP_HEAD(prefix, op, result_type) \
template < \
class Derived1, class V1, class TC1, class Reference1, class Difference1 \
, class Derived2, class V2, class TC2, class Reference2, class Difference2 \
> \
prefix typename boost::detail::enable_if_interoperable< \
Derived1, Derived2 \
, typename mpl::apply2<result_type,Derived1,Derived2>::type \
>::type \
operator op( \
iterator_facade<Derived1, V1, TC1, Reference1, Difference1> const& lhs \
, iterator_facade<Derived2, V2, TC2, Reference2, Difference2> const& rhs)
# endif
# define BOOST_ITERATOR_FACADE_PLUS_HEAD(prefix,args) \
template <class Derived, class V, class TC, class R, class D> \
prefix Derived operator+ args
//
// Helper class for granting access to the iterator core interface.
//
// The simple core interface is used by iterator_facade. The core
// interface of a user/library defined iterator type should not be made public
// so that it does not clutter the public interface. Instead iterator_core_access
// should be made friend so that iterator_facade can access the core
// interface through iterator_core_access.
//
class iterator_core_access
{
# if defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
// Tasteless as this may seem, making all members public allows member templates
// to work in the absence of member template friends.
public:
# else
template <class I, class V, class TC, class R, class D> friend class iterator_facade;
# define BOOST_ITERATOR_FACADE_RELATION(op) \
BOOST_ITERATOR_FACADE_INTEROP_HEAD(friend,op, boost::detail::always_bool2);
BOOST_ITERATOR_FACADE_RELATION(==)
BOOST_ITERATOR_FACADE_RELATION(!=)
BOOST_ITERATOR_FACADE_RELATION(<)
BOOST_ITERATOR_FACADE_RELATION(>)
BOOST_ITERATOR_FACADE_RELATION(<=)
BOOST_ITERATOR_FACADE_RELATION(>=)
# undef BOOST_ITERATOR_FACADE_RELATION
BOOST_ITERATOR_FACADE_INTEROP_HEAD(
friend, -, boost::detail::choose_difference_type)
;
BOOST_ITERATOR_FACADE_PLUS_HEAD(
friend inline
, (iterator_facade<Derived, V, TC, R, D> const&
, typename Derived::difference_type)
)
;
BOOST_ITERATOR_FACADE_PLUS_HEAD(
friend inline
, (typename Derived::difference_type
, iterator_facade<Derived, V, TC, R, D> const&)
)
;
# endif
template <class Facade>
static typename Facade::reference dereference(Facade const& f)
{
return f.dereference();
}
template <class Facade>
static void increment(Facade& f)
{
f.increment();
}
template <class Facade>
static void decrement(Facade& f)
{
f.decrement();
}
template <class Facade1, class Facade2>
static bool equal(Facade1 const& f1, Facade2 const& f2, mpl::true_)
{
return f1.equal(f2);
}
template <class Facade1, class Facade2>
static bool equal(Facade1 const& f1, Facade2 const& f2, mpl::false_)
{
return f2.equal(f1);
}
template <class Facade>
static void advance(Facade& f, typename Facade::difference_type n)
{
f.advance(n);
}
template <class Facade1, class Facade2>
static typename Facade1::difference_type distance_from(
Facade1 const& f1, Facade2 const& f2, mpl::true_)
{
return -f1.distance_to(f2);
}
template <class Facade1, class Facade2>
static typename Facade2::difference_type distance_from(
Facade1 const& f1, Facade2 const& f2, mpl::false_)
{
return f2.distance_to(f1);
}
//
// Curiously Recurring Template interface.
//
template <class I, class V, class TC, class R, class D>
static I& derived(iterator_facade<I,V,TC,R,D>& facade)
{
return *static_cast<I*>(&facade);
}
template <class I, class V, class TC, class R, class D>
static I const& derived(iterator_facade<I,V,TC,R,D> const& facade)
{
return *static_cast<I const*>(&facade);
}
private:
// objects of this class are useless
iterator_core_access(); //undefined
};
//
// iterator_facade - use as a public base class for defining new
// standard-conforming iterators.
//
template <
class Derived // The derived iterator type being constructed
, class Value
, class CategoryOrTraversal
, class Reference = Value&
, class Difference = std::ptrdiff_t
>
class iterator_facade
# ifdef BOOST_ITERATOR_FACADE_NEEDS_ITERATOR_BASE
: public boost::detail::iterator_facade_types<
Value, CategoryOrTraversal, Reference, Difference
>::base
# undef BOOST_ITERATOR_FACADE_NEEDS_ITERATOR_BASE
# endif
{
private:
//
// Curiously Recurring Template interface.
//
Derived& derived()
{
return *static_cast<Derived*>(this);
}
Derived const& derived() const
{
return *static_cast<Derived const*>(this);
}
typedef boost::detail::iterator_facade_types<
Value, CategoryOrTraversal, Reference, Difference
> associated_types;
protected:
// For use by derived classes
typedef iterator_facade<Derived,Value,CategoryOrTraversal,Reference,Difference> iterator_facade_;
public:
typedef typename associated_types::value_type value_type;
typedef Reference reference;
typedef Difference difference_type;
typedef typename associated_types::pointer pointer;
typedef typename associated_types::iterator_category iterator_category;
reference operator*() const
{
return iterator_core_access::dereference(this->derived());
}
typename boost::detail::operator_arrow_result<
value_type
, reference
, pointer
>::type
operator->() const
{
return boost::detail::operator_arrow_result<
value_type
, reference
, pointer
>::make(*this->derived());
}
typename boost::detail::operator_brackets_result<Derived,Value,reference>::type
operator[](difference_type n) const
{
typedef boost::detail::use_operator_brackets_proxy<Value,Reference> use_proxy;
return boost::detail::make_operator_brackets_result<Derived>(
this->derived() + n
, use_proxy()
);
}
Derived& operator++()
{
iterator_core_access::increment(this->derived());
return this->derived();
}
# if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
typename boost::detail::postfix_increment_result<Derived,Value,Reference,CategoryOrTraversal>::type
operator++(int)
{
typename boost::detail::postfix_increment_result<Derived,Value,Reference,CategoryOrTraversal>::type
tmp(this->derived());
++*this;
return tmp;
}
# endif
Derived& operator--()
{
iterator_core_access::decrement(this->derived());
return this->derived();
}
Derived operator--(int)
{
Derived tmp(this->derived());
--*this;
return tmp;
}
Derived& operator+=(difference_type n)
{
iterator_core_access::advance(this->derived(), n);
return this->derived();
}
Derived& operator-=(difference_type n)
{
iterator_core_access::advance(this->derived(), -n);
return this->derived();
}
Derived operator-(difference_type x) const
{
Derived result(this->derived());
return result -= x;
}
# if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
// There appears to be a bug which trashes the data of classes
// derived from iterator_facade when they are assigned unless we
// define this assignment operator. This bug is only revealed
// (so far) in STLPort debug mode, but it's clearly a codegen
// problem so we apply the workaround for all MSVC6.
iterator_facade& operator=(iterator_facade const&)
{
return *this;
}
# endif
};
# if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)
template <class I, class V, class TC, class R, class D>
inline typename boost::detail::postfix_increment_result<I,V,R,TC>::type
operator++(
iterator_facade<I,V,TC,R,D>& i
, int
)
{
typename boost::detail::postfix_increment_result<I,V,R,TC>::type
tmp(*static_cast<I*>(&i));
++i;
return tmp;
}
# endif
//
// Comparison operator implementation. The library supplied operators
// enables the user to provide fully interoperable constant/mutable
// iterator types. I.e. the library provides all operators
// for all mutable/constant iterator combinations.
//
// Note though that this kind of interoperability for constant/mutable
// iterators is not required by the standard for container iterators.
// All the standard asks for is a conversion mutable -> constant.
// Most standard library implementations nowadays provide fully interoperable
// iterator implementations, but there are still heavily used implementations
// that do not provide them. (Actually it's even worse, they do not provide
// them for only a few iterators.)
//
// ?? Maybe a BOOST_ITERATOR_NO_FULL_INTEROPERABILITY macro should
// enable the user to turn off mixed type operators
//
// The library takes care to provide only the right operator overloads.
// I.e.
//
// bool operator==(Iterator, Iterator);
// bool operator==(ConstIterator, Iterator);
// bool operator==(Iterator, ConstIterator);
// bool operator==(ConstIterator, ConstIterator);
//
// ...
//
// In order to do so it uses c++ idioms that are not yet widely supported
// by current compiler releases. The library is designed to degrade gracefully
// in the face of compiler deficiencies. In general compiler
// deficiencies result in less strict error checking and more obscure
// error messages, functionality is not affected.
//
// For full operation compiler support for "Substitution Failure Is Not An Error"
// (aka. enable_if) and boost::is_convertible is required.
//
// The following problems occur if support is lacking.
//
// Pseudo code
//
// ---------------
// AdaptorA<Iterator1> a1;
// AdaptorA<Iterator2> a2;
//
// // This will result in a no such overload error in full operation
// // If enable_if or is_convertible is not supported
// // The instantiation will fail with an error hopefully indicating that
// // there is no operator== for Iterator1, Iterator2
// // The same will happen if no enable_if is used to remove
// // false overloads from the templated conversion constructor
// // of AdaptorA.
//
// a1 == a2;
// ----------------
//
// AdaptorA<Iterator> a;
// AdaptorB<Iterator> b;
//
// // This will result in a no such overload error in full operation
// // If enable_if is not supported the static assert used
// // in the operator implementation will fail.
// // This will accidently work if is_convertible is not supported.
//
// a == b;
// ----------------
//
# ifdef BOOST_NO_ONE_WAY_ITERATOR_INTEROP
# define BOOST_ITERATOR_CONVERTIBLE(a,b) mpl::true_()
# else
# define BOOST_ITERATOR_CONVERTIBLE(a,b) is_convertible<a,b>()
# endif
# define BOOST_ITERATOR_FACADE_INTEROP(op, result_type, return_prefix, base_op) \
BOOST_ITERATOR_FACADE_INTEROP_HEAD(inline, op, result_type) \
{ \
/* For those compilers that do not support enable_if */ \
BOOST_STATIC_ASSERT(( \
is_interoperable< Derived1, Derived2 >::value \
)); \
return_prefix iterator_core_access::base_op( \
*static_cast<Derived1 const*>(&lhs) \
, *static_cast<Derived2 const*>(&rhs) \
, BOOST_ITERATOR_CONVERTIBLE(Derived2,Derived1) \
); \
}
# define BOOST_ITERATOR_FACADE_RELATION(op, return_prefix, base_op) \
BOOST_ITERATOR_FACADE_INTEROP( \
op \
, boost::detail::always_bool2 \
, return_prefix \
, base_op \
)
BOOST_ITERATOR_FACADE_RELATION(==, return, equal)
BOOST_ITERATOR_FACADE_RELATION(!=, return !, equal)
BOOST_ITERATOR_FACADE_RELATION(<, return 0 >, distance_from)
BOOST_ITERATOR_FACADE_RELATION(>, return 0 <, distance_from)
BOOST_ITERATOR_FACADE_RELATION(<=, return 0 >=, distance_from)
BOOST_ITERATOR_FACADE_RELATION(>=, return 0 <=, distance_from)
# undef BOOST_ITERATOR_FACADE_RELATION
// operator- requires an additional part in the static assertion
BOOST_ITERATOR_FACADE_INTEROP(
-
, boost::detail::choose_difference_type
, return
, distance_from
)
# undef BOOST_ITERATOR_FACADE_INTEROP
# undef BOOST_ITERATOR_FACADE_INTEROP_HEAD
# define BOOST_ITERATOR_FACADE_PLUS(args) \
BOOST_ITERATOR_FACADE_PLUS_HEAD(inline, args) \
{ \
Derived tmp(static_cast<Derived const&>(i)); \
return tmp += n; \
}
BOOST_ITERATOR_FACADE_PLUS((
iterator_facade<Derived, V, TC, R, D> const& i
, typename Derived::difference_type n
))
BOOST_ITERATOR_FACADE_PLUS((
typename Derived::difference_type n
, iterator_facade<Derived, V, TC, R, D> const& i
))
# undef BOOST_ITERATOR_FACADE_PLUS
# undef BOOST_ITERATOR_FACADE_PLUS_HEAD
} // namespace boost
#include <boost/iterator/detail/config_undef.hpp>
#endif // BOOST_ITERATOR_FACADE_23022003THW_HPP
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