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merged from trunk

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[SVN r21580]
This commit is contained in:
Dave Abrahams
2004-01-11 00:35:03 +00:00
parent f1d694c2d6
commit 6379561eb0
6 changed files with 89 additions and 55 deletions
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35
doc/iterator_facade_body.rst
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@ -46,14 +46,15 @@ objects for several reasons:
Usage
-----
The user of ``iterator_facade`` derives his iterator class from an
specialization of ``iterator_facade`` which takes the derived iterator
class as the first template parameter. The order of the other
template parameters to ``iterator_facade`` have been carefully chosen
to take advantage of useful defaults. For example, when defining a
constant lvalue iterator, the user can pass a const-qualified version
of the iterator's ``value_type`` as ``iterator_facade``\ 's ``Value``
parameter and omit the ``Reference`` parameter which follows.
The user of ``iterator_facade`` derives his iterator class from a
specialization of ``iterator_facade`` and passes the derived
iterator class as ``iterator_facade``\ 's first template parameter.
The order of the other template parameters have been carefully
chosen to take advantage of useful defaults. For example, when
defining a constant lvalue iterator, the user can pass a
const-qualified version of the iterator's ``value_type`` as
``iterator_facade``\ 's ``Value`` parameter and omit the
``Reference`` parameter which follows.
The derived iterator class must define member functions implementing
the iterator's core behaviors. The following table describes
@ -150,14 +151,16 @@ into the temporary iterator ``p+n``, which is destroyed when
Writable iterators built with ``iterator_facade`` implement the
semantics required by the preferred resolution to `issue 299`_ and
adopted by proposal n1550_: the result of ``p[n]`` is a proxy object
containing a copy of ``p+n``, and ``p[n] = x`` is equivalent to ``*(p
+ n) = x``. This approach will work properly for any random-access
iterator regardless of the other details of its implementation. A
user who knows more about the implementation of her iterator is free
to implement an ``operator[]`` which returns an lvalue in the derived
iterator class; it will hide the one supplied by ``iterator_facade``
from clients of her iterator.
adopted by proposal n1550_: the result of ``p[n]`` is an object
convertible to the iterator's ``value_type``, and ``p[n] = x`` is
equivalent to ``*(p + n) = x`` (Note: This result object may be
implemented as a proxy containing a copy of ``p+n``). This approach
will work properly for any random-access iterator regardless of the
other details of its implementation. A user who knows more about
the implementation of her iterator is free to implement an
``operator[]`` that returns an lvalue in the derived iterator
class; it will hide the one supplied by ``iterator_facade`` from
clients of her iterator.
.. _n1550: http://anubis.dkuug.dk/JTC1/SC22/WG21/docs/papers/2003/n1550.html

11
doc/iterator_facade_ref.rst
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@ -245,10 +245,13 @@ __ `operator arrow`_
*unspecified* ``operator[](difference_type n) const;``
:Returns: an object convertible to ``reference`` and holding a copy
*p* of ``*static_cast<Derived const*>(this) + n`` such that, for a constant object ``v`` of type
``value_type``, ``(*static_cast<Derived const*>(this))[n] = v`` is equivalent
to ``p = v``.
:Returns: an object convertible to ``value_type``. For constant
objects ``v`` of type ``value_type``, and ``n`` of type
``difference_type``, and reference ``p`` equal to
``*static_cast<Derived const*>(this)``, ``(*this)[n] = v`` is
equivalent to ``*(p+ n) = v``, and ``static_cast<value_type
const&>((*this)[n])`` is equivalent to
``static_cast<value_type const&>(*(p+n))``

19
include/boost/iterator/iterator_facade.hpp
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@ -22,9 +22,11 @@
#include <boost/type_traits/add_pointer.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/is_convertible.hpp>
#include <boost/type_traits/is_POD.hpp>
#include <boost/mpl/apply_if.hpp>
#include <boost/mpl/or.hpp>
#include <boost/mpl/and.hpp>
#include <boost/iterator/detail/config_def.hpp> // this goes last
@ -182,11 +184,21 @@ namespace boost
Iterator m_iter;
};
template <class Value, class Reference>
struct use_operator_brackets_proxy
: mpl::and_<
// Really we want an is_copy_constructible trait here,
// but is_POD will have to suffice in the meantime.
boost::is_POD<Value>
, iterator_writability_disabled<Value,Reference>
>
{};
template <class Iterator, class Value, class Reference>
struct operator_brackets_result
{
typedef typename mpl::if_<
iterator_writability_disabled<Value,Reference>
use_operator_brackets_proxy<Value,Reference>
, Value
, operator_brackets_proxy<Iterator>
>::type type;
@ -387,12 +399,11 @@ namespace boost
typename detail::operator_brackets_result<Derived,Value,Reference>::type
operator[](difference_type n) const
{
typedef detail::iterator_writability_disabled<Value,Reference>
not_writable;
typedef detail::use_operator_brackets_proxy<Value,Reference> use_proxy;
return detail::make_operator_brackets_result<Derived>(
this->derived() + n
, not_writable()
, use_proxy()
);
}

40
include/boost/pointee.hpp
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@ -9,7 +9,9 @@
# include <boost/detail/is_incrementable.hpp>
# include <boost/iterator/iterator_traits.hpp>
# include <boost/type_traits/add_const.hpp>
# include <boost/type_traits/remove_cv.hpp>
# include <boost/mpl/if.hpp>
# include <boost/mpl/apply_if.hpp>
namespace boost {
@ -17,9 +19,37 @@ namespace boost {
namespace detail
{
template <class P>
struct smart_ptr_value
struct smart_ptr_pointee
{
typedef typename remove_cv<typename P::element_type>::type type;
typedef typename P::element_type type;
};
template <class Iterator>
struct iterator_pointee
{
typedef typename iterator_traits<Iterator>::value_type value_type;
struct impl
{
template <class T>
static char test(T const&);
static char (& test(value_type&) )[2];
static Iterator& x;
};
BOOST_STATIC_CONSTANT(bool, is_constant = sizeof(impl::test(*impl::x)) == 1);
typedef typename mpl::if_c<
# if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551))
::boost::detail::iterator_pointee<Iterator>::is_constant
# else
is_constant
# endif
, typename add_const<value_type>::type
, value_type
>::type type;
};
}
@ -27,11 +57,11 @@ template <class P>
struct pointee
{
typedef typename remove_cv<P>::type stripped;
typedef typename mpl::apply_if<
detail::is_incrementable<stripped>
, iterator_value<stripped>
, detail::smart_ptr_value<stripped>
, detail::iterator_pointee<stripped>
, detail::smart_ptr_pointee<stripped>
>::type type;
};

3
test/Jamfile
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@ -6,6 +6,8 @@
subproject libs/iterator/test ;
subinclude libs/iterator/example ;
import testing ;
test-suite iterator
@ -29,6 +31,7 @@ test-suite iterator
# These tests should work for just about everything.
[ compile is_lvalue_iterator.cpp ]
[ compile is_readable_iterator.cpp ]
[ compile pointee.cpp ]
[ run unit_tests.cpp ]
[ run concept_tests.cpp ]

36
test/indirect_iterator_member_types.cpp
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@ -30,19 +30,8 @@ struct my_ptr {
BOOST_TT_BROKEN_COMPILER_SPEC(my_ptr)
BOOST_TT_BROKEN_COMPILER_SPEC(zow)
#ifndef BOOST_ITERATOR_REF_CONSTNESS_KILLS_WRITABILITY
# define STATIC_ASSERT_SAME_POINTER(P1, P2) \
STATIC_ASSERT_SAME( \
boost::remove_const<boost::remove_pointer<P1>::type>::type \
, boost::remove_const<boost::remove_pointer<P2>::type>::type \
)
#else
# define STATIC_ASSERT_SAME_POINTER(P1, P2) STATIC_ASSERT_SAME(P1,P2)
#endif
// Borland 5.6.4 and earlier drop const all over the place, so this
// test will fail in the lines marked with (**)
int main()
{
@ -50,7 +39,7 @@ int main()
typedef boost::indirect_iterator<int**> Iter;
STATIC_ASSERT_SAME(Iter::value_type, int);
STATIC_ASSERT_SAME(Iter::reference, int&);
STATIC_ASSERT_SAME_POINTER(Iter::pointer, int*);
STATIC_ASSERT_SAME(Iter::pointer, int*);
STATIC_ASSERT_SAME(Iter::difference_type, std::ptrdiff_t);
BOOST_STATIC_ASSERT((boost::is_convertible<Iter::iterator_category,
@ -62,31 +51,26 @@ int main()
typedef boost::indirect_iterator<int const**> Iter;
STATIC_ASSERT_SAME(Iter::value_type, int);
STATIC_ASSERT_SAME(Iter::reference, const int&);
#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) // Borland drops const all over the place
STATIC_ASSERT_SAME_POINTER(Iter::pointer, const int*);
#endif
STATIC_ASSERT_SAME(Iter::pointer, const int*); // (**)
}
{
typedef boost::indirect_iterator<int**, int> Iter;
STATIC_ASSERT_SAME(Iter::value_type, int);
STATIC_ASSERT_SAME(Iter::reference, int&);
STATIC_ASSERT_SAME_POINTER(Iter::pointer, int*);
STATIC_ASSERT_SAME(Iter::pointer, int*);
}
{
typedef boost::indirect_iterator<int**, const int> Iter;
STATIC_ASSERT_SAME(Iter::value_type, int);
STATIC_ASSERT_SAME(Iter::reference, const int&);
#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) // Borland drops const all over the place
STATIC_ASSERT_SAME_POINTER(Iter::pointer, const int*);
#endif
STATIC_ASSERT_SAME(Iter::pointer, const int*); // (**)
}
{
typedef boost::indirect_iterator<my_ptr*> Iter;
STATIC_ASSERT_SAME(Iter::value_type, zow);
#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) // Borland drops const all over the place
STATIC_ASSERT_SAME(Iter::reference, const zow&);
STATIC_ASSERT_SAME_POINTER(Iter::pointer, const zow*);
#endif
STATIC_ASSERT_SAME(Iter::reference, const zow&); // (**)
STATIC_ASSERT_SAME(Iter::pointer, const zow*); // (**)
STATIC_ASSERT_SAME(Iter::difference_type, std::ptrdiff_t);
BOOST_STATIC_ASSERT((boost::is_convertible<Iter::iterator_category,
@ -98,7 +82,7 @@ int main()
typedef boost::indirect_iterator<char**, int, std::random_access_iterator_tag, long&, short> Iter;
STATIC_ASSERT_SAME(Iter::value_type, int);
STATIC_ASSERT_SAME(Iter::reference, long&);
STATIC_ASSERT_SAME_POINTER(Iter::pointer, int*);
STATIC_ASSERT_SAME(Iter::pointer, int*);
STATIC_ASSERT_SAME(Iter::difference_type, short);
}
return 0;