feedc0de/boost_iterator
1
0
Fork 0
forked from boostorg/iterator
Code Pull Requests Activity

initial commit

Browse Source 
[SVN r19978]
This commit is contained in:
Dave Abrahams
2003-09-09 03:22:50 +00:00
parent 3f49409843
commit 2c89e2b15a
2 changed files with 1662 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

680
include/boost/iterator/zip_iterator.hpp Executable file
View File

@ -0,0 +1,680 @@
// (C) Copyright David Abrahams and Thomas Becker 2000. Permission to
// copy, use, modify, sell and distribute this software is granted
// provided this copyright notice appears in all copies. This software
// is provided "as is" without express or implied warranty, and with
// no claim as to its suitability for any purpose.
//
// Compilers Tested:
// =================
// Metrowerks Codewarrior Pro 7.2, 8.3
// gcc 2.95.3
// gcc 3.2
// Microsoft VC 6sp5 (test fails due to some compiler bug)
// Microsoft VC 7 (works)
// Microsoft VC 7.1
// Intel 5
// Intel 6
// Intel 7.1
// Intel 8
// Borland 5.5.1 (broken due to lack of support from Boost.Tuples)
#ifndef BOOST_ZIP_ITERATOR_TMB_07_13_2003_HPP_
#include <stddef.h>
#include <boost/iterator.hpp>
#include <boost/iterator/iterator_traits.hpp>
#include <boost/iterator/iterator_facade.hpp>
#include <boost/iterator/iterator_adaptor.hpp> // for enable_if_convertible
#include <boost/iterator/iterator_categories.hpp>
#include <boost/tuple/tuple.hpp>
#if BOOST_WORKAROUND(__GNUC__, == 2) || BOOST_WORKAROUND(__MWERKS__, <= 0x2407)
# include <boost/type_traits/remove_cv.hpp>
#endif
#include <boost/type_traits/is_same.hpp>
#include <boost/mpl/and.hpp>
#include <boost/mpl/apply.hpp>
#include <boost/mpl/apply_if.hpp>
#include <boost/mpl/lambda.hpp>
#include <boost/mpl/placeholders.hpp>
#include <boost/mpl/aux_/lambda_support.hpp>
namespace boost {
// Zip iterator forward declaration for zip_iterator_base
template<typename IteratorTuple>
class zip_iterator;
// One important design goal of the zip_iterator is to isolate all
// functionality whose implementation relies on the current tuple
// implementation. This goal has been achieved as follows: Inside
// the namespace detail there is a namespace tuple_impl_specific.
// This namespace encapsulates all functionality that is specific
// to the current Boost tuple implementation. More precisely, the
// namespace tuple_impl_specific provides the following tuple
// algorithms and meta-algorithms for the current Boost tuple
// implementation:
//
// tuple_meta_transform
// tuple_meta_accumulate
// tuple_transform
// tuple_for_each
//
// If the tuple implementation changes, all that needs to be
// replaced is the implementation of these four (meta-)algorithms.
//
// Unfortunately, some compilers, including Metrowerks Codewarrior
// 4.2.5.766 and gcc 3.3, were unable to handle the template
// code involved (Metrowerks: internal compiler error, gcc 3.3:
// segmentation fault). Therefore, rather regrettably, for those
// compilers, the encapsulation of the tuple implementation-
// specific code is not nearly as nice and clean as it should be.
// In order to emphasize this point, I have provided the entire
// namespace detail in this file twice: the first version is the
// clean one with the nice encapsulation, the second one is the
// dirty one.
//
namespace detail
{
// Functors to be used with tuple algorithms
//
template<typename DiffType>
class advance_iterator
{
public:
advance_iterator(DiffType step) : m_step(step) {}
template<typename Iterator>
void operator()(Iterator& it) const
{ it += m_step; }
private:
DiffType m_step;
};
//
struct increment_iterator
{
template<typename Iterator>
void operator()(Iterator& it)
{ ++it; }
};
//
struct decrement_iterator
{
template<typename Iterator>
void operator()(Iterator& it)
{ --it; }
};
//
struct dereference_iterator
{
template<typename Iterator>
struct apply
{
#if BOOST_WORKAROUND(__GNUC__, == 2) || BOOST_WORKAROUND(__MWERKS__, <= 0x2407)
typedef typename
std::iterator_traits<
typename boost::remove_cv<Iterator>::type
>::reference
type;
#else
typedef typename
std::iterator_traits<Iterator>::reference
type;
#endif
};
template<typename Iterator>
typename apply<Iterator>::type operator()(Iterator& it)
{ return *it; }
};
// The namespace tuple_impl_specific provides two meta-
// algorithms and two algorithms for tuples.
//
namespace tuple_impl_specific
{
// Meta-transform algorithm for tuples
//
template<typename Tuple, class UnaryMetaFun>
struct tuple_meta_transform;
template<typename Tuple, class UnaryMetaFun>
struct tuple_meta_transform_impl
{
typedef tuples::cons<
typename mpl::apply1<
typename mpl::lambda<UnaryMetaFun>::type
, typename Tuple::head_type
>::type
, typename tuple_meta_transform<
typename Tuple::tail_type
, UnaryMetaFun
>::type
> type;
};
template<typename Tuple, class UnaryMetaFun>
struct tuple_meta_transform
: mpl::apply_if<
boost::is_same<Tuple, tuples::null_type>
, mpl::identity<tuples::null_type>
, tuple_meta_transform_impl<Tuple, UnaryMetaFun>
>
{
};
// Meta-accumulate algorithm for tuples. Note: The template
// parameter StartType corresponds to the initial value in
// ordinary accumulation.
//
template<class Tuple, class BinaryMetaFun, class StartType>
struct tuple_meta_accumulate;
template<
typename Tuple
, class BinaryMetaFun
, typename StartType
>
struct tuple_meta_accumulate_impl
{
typedef typename mpl::apply2<
typename mpl::lambda<BinaryMetaFun>::type
, typename Tuple::head_type
, typename tuple_meta_accumulate<
typename Tuple::tail_type
, BinaryMetaFun
, StartType
>::type
>::type type;
};
template<
typename Tuple
, class BinaryMetaFun
, typename StartType
>
struct tuple_meta_accumulate
: mpl::apply_if<
#if BOOST_WORKAROUND(BOOST_MSVC, == 1200)
mpl::or_<
#endif
boost::is_same<Tuple, tuples::null_type>
#if BOOST_WORKAROUND(BOOST_MSVC, == 1200)
, boost::is_same<Tuple,int>
>
#endif
, mpl::identity<StartType>
, tuple_meta_accumulate_impl<
Tuple
, BinaryMetaFun
, StartType
>
>
{
};
#if defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING) \
|| ( \
BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION, != 0) && defined(_MSC_VER) \
)
// Not sure why intel's partial ordering fails in this case, but I'm
// assuming int's an MSVC bug-compatibility feature.
# define BOOST_TUPLE_ALGO_DISPATCH
# define BOOST_TUPLE_ALGO(algo) algo##_impl
# define BOOST_TUPLE_ALGO_TERMINATOR , int
# define BOOST_TUPLE_ALGO_RECURSE , ...
#else
# define BOOST_TUPLE_ALGO(algo) algo
# define BOOST_TUPLE_ALGO_TERMINATOR
# define BOOST_TUPLE_ALGO_RECURSE
#endif
// transform algorithm for tuples. The template parameter Fun
// must be a unary functor which is also a unary metafunction
// class that computes its return type based on its argument
// type. For example:
//
// struct to_ptr
// {
// template <class Arg>
// struct apply
// {
// typedef Arg* type;
// }
//
// template <class Arg>
// Arg* operator()(Arg x);
// };
template<typename Fun>
tuples::null_type BOOST_TUPLE_ALGO(tuple_transform)
(tuples::null_type const&, Fun BOOST_TUPLE_ALGO_TERMINATOR)
{ return tuples::null_type(); }
template<typename Tuple, typename Fun>
typename tuple_meta_transform<
Tuple
, Fun
>::type
BOOST_TUPLE_ALGO(tuple_transform)(
const Tuple& t,
Fun f
BOOST_TUPLE_ALGO_RECURSE
)
{
typedef typename tuple_meta_transform<
typename Tuple::tail_type
, Fun
>::type transformed_tail_type;
return tuples::cons<
typename mpl::apply1<Fun, typename Tuple::head_type>::type
, transformed_tail_type
>(
f(boost::tuples::get<0>(t)),
tuple_transform(t.get_tail(), f)
);
}
#ifdef BOOST_TUPLE_ALGO_DISPATCH
template<typename Tuple, typename Fun>
typename tuple_meta_transform<
Tuple
, Fun
>::type
tuple_transform(
const Tuple& t,
Fun f
)
{
return tuple_transform_impl(t, f, 1);
}
#endif
// for_each algorithm for tuples.
//
template<typename Fun>
Fun BOOST_TUPLE_ALGO(tuple_for_each)(
tuples::null_type
, Fun f BOOST_TUPLE_ALGO_TERMINATOR
)
{ return f; }
template<typename Tuple, typename Fun>
Fun BOOST_TUPLE_ALGO(tuple_for_each)(
Tuple& t
, Fun f BOOST_TUPLE_ALGO_RECURSE)
{
f( t.get_head() );
return tuple_for_each(t.get_tail(), f);
}
#ifdef BOOST_TUPLE_ALGO_DISPATCH
template<typename Tuple, typename Fun>
Fun
tuple_for_each(
Tuple& t,
Fun f
)
{
return tuple_for_each_impl(t, f, 1);
}
#endif
// Equality of tuples. NOTE: "==" for tuples currently (7/2003)
// has problems under some compilers, so I just do my own.
// No point in bringing in a bunch of #ifdefs here. This is
// going to go away with the next tuple implementation anyway.
//
bool tuple_equal(tuples::null_type, tuples::null_type)
{ return true; }
template<typename Tuple1, typename Tuple2>
bool tuple_equal(
Tuple1 const& t1,
Tuple2 const& t2
)
{
return t1.get_head() == t2.get_head() &&
tuple_equal(t1.get_tail(), t2.get_tail());
}
}
//
// end namespace tuple_impl_specific
template<typename Iterator>
struct iterator_reference
{
typedef typename iterator_traits<Iterator>::reference type;
};
#ifdef BOOST_MPL_NO_FULL_LAMBDA_SUPPORT
// Hack because BOOST_MPL_AUX_LAMBDA_SUPPORT doesn't seem to work
// out well. Instantiating the nested apply template also
// requires instantiating iterator_traits on the
// placeholder. Instead we just specialize it as a metafunction
// class.
template<>
struct iterator_reference<mpl::_1>
{
template <class T>
struct apply : iterator_reference<T> {};
};
#endif
// Metafunction to obtain the type of the tuple whose element types
// are the reference types of an iterator tuple.
//
template<typename IteratorTuple>
struct tuple_of_references
: tuple_impl_specific::tuple_meta_transform<
IteratorTuple,
iterator_reference<mpl::_1>
>
{
};
// Metafunction to obtain the minimal traversal tag in a tuple
// of iterators.
//
template<typename IteratorTuple>
struct minimum_traversal_category_in_iterator_tuple
{
typedef typename tuple_impl_specific::tuple_meta_transform<
IteratorTuple
, traversal_category<mpl::_1>
>::type tuple_of_traversal_tags;
typedef typename tuple_impl_specific::tuple_meta_accumulate<
tuple_of_traversal_tags
, minimum_category<mpl::_1,mpl::_2>
, random_access_traversal_tag
>::type type;
};
#if BOOST_WORKAROUND(BOOST_MSVC, == 1200) // ETI workaround
template <>
struct minimum_traversal_category_in_iterator_tuple<int>
{
typedef int type;
};
#endif
template<typename Iterator>
struct iterator_is_readable
: is_tag<
readable_iterator_tag
, typename access_category<Iterator>::type
>
{
BOOST_MPL_AUX_LAMBDA_SUPPORT(1, iterator_is_readable, (Iterator))
};
# ifdef BOOST_MPL_NO_FULL_LAMBDA_SUPPORT
// Hack because BOOST_MPL_AUX_LAMBDA_SUPPORT doesn't seem to work
// out well. Instantiating the nested apply template also
// requires instantiating iterator_traits on the
// placeholder. Instead we just specialize it as a metafunction
// class.
template <>
struct iterator_is_readable<mpl::_1>
{
template <class T>
struct apply : iterator_is_readable<T>
{};
};
# endif
// We need to call tuple_meta_accumulate with mpl::and_ as the
// accumulating functor. To this end, we need to wrap it into
// a struct that has exactly two arguments (that is, template
// parameters) and not five, like mpl::and_ does.
//
template<typename Arg1, typename Arg2>
struct and_with_two_args
: mpl::and_<Arg1, Arg2>
{
};
# ifdef BOOST_MPL_NO_FULL_LAMBDA_SUPPORT
// Hack because BOOST_MPL_AUX_LAMBDA_SUPPORT doesn't seem to work
// out well. In this case I think it's an MPL bug
template<>
struct and_with_two_args<mpl::_1,mpl::_2>
{
template <class A1, class A2>
struct apply : mpl::and_<A1,A2>
{};
};
# endif
// Metafunction to assert that all iterators in a tuple are
// readable.
//
// Probably not worth it, IMO. Why not a writable zip_iterator
// anyway? -- dwa.
//
template<typename IteratorTuple>
struct all_iterators_in_tuple_readable
{
typedef typename tuple_impl_specific::tuple_meta_transform<
IteratorTuple,
iterator_is_readable<mpl::_1>
>::type tuple_of_readability_bools;
typedef typename tuple_impl_specific::tuple_meta_accumulate<
tuple_of_readability_bools,
and_with_two_args<mpl::_1,mpl::_2>
, mpl::bool_<true>
>::type type;
};
///////////////////////////////////////////////////////////////////
//
// Class zip_iterator_base
//
// Builds and exposes the iterator facade type from which the zip
// iterator will be derived.
//
template<typename IteratorTuple>
struct zip_iterator_base
{
private:
#if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
// seems to give vc7's parser fits, and vc6 needs help here too
BOOST_STATIC_ASSERT(
detail::all_iterators_in_tuple_readable<
IteratorTuple
>::type::value
);
#endif
// Reference type is the type of the tuple obtained from the
// iterators' reference types.
typedef typename
detail::tuple_of_references<IteratorTuple>::type reference;
// Value type is the same as reference type.
typedef reference value_type;
// Difference type is the first iterator's difference type
typedef typename iterator_traits<
typename tuples::element<0, IteratorTuple>::type
>::difference_type difference_type;
// Traversal catetgory is the minimum traversal category in the
// iterator tuple.
typedef typename
detail::minimum_traversal_category_in_iterator_tuple<
IteratorTuple
>::type traversal_category;
// Access category is readable_iterator_tag. It has been
// asserted that all iterators in the tuple are readable.
typedef readable_iterator_tag access_category;
public:
// The iterator facade type from which the zip iterator will
// be derived.
typedef iterator_facade<
zip_iterator<IteratorTuple>,
value_type,
access_category,
traversal_category,
reference,
difference_type
> type;
};
template <>
struct zip_iterator_base<int>
{
typedef int type;
};
}
/////////////////////////////////////////////////////////////////////
//
// zip_iterator class definition
//
template<typename IteratorTuple>
class zip_iterator :
public detail::zip_iterator_base<IteratorTuple>::type
{
// Typedef super_t as our base class.
typedef typename
detail::zip_iterator_base<IteratorTuple>::type super_t;
// iterator_core_access is the iterator's best friend.
friend class iterator_core_access;
public:
// Construction
// ============
// Default constructor
zip_iterator() { }
// Constructor from iterator tuple
zip_iterator(IteratorTuple iterator_tuple)
: m_iterator_tuple(iterator_tuple)
{ }
// Copy constructor
template<typename OtherIteratorTuple>
zip_iterator(
const zip_iterator<OtherIteratorTuple>& other,
typename enable_if_convertible<
OtherIteratorTuple,
IteratorTuple
>::type* = 0
) : m_iterator_tuple(other.get_iterator_tuple())
{}
// Get method for the iterator tuple.
const IteratorTuple& get_iterator_tuple() const
{ return m_iterator_tuple; }
private:
// Implementation of Iterator Operations
// =====================================
// Dereferencing returns a tuple built from the dereferenced
// iterators in the iterator tuple.
typename super_t::reference dereference() const
{
return detail::tuple_impl_specific::tuple_transform(
get_iterator_tuple(),
detail::dereference_iterator()
);
}
// Two zip iterators are equal if all iterators in the iterator
// tuple are equal. NOTE: It should be possible to implement this
// as
//
// return get_iterator_tuple() == other.get_iterator_tuple();
//
// but equality of tuples currently (7/2003) does not compile
// under several compilers. No point in bringing in a bunch
// of #ifdefs here.
//
template<typename OtherIteratorTuple>
bool equal(const zip_iterator<OtherIteratorTuple>& other) const
{
return detail::tuple_impl_specific::tuple_equal(
get_iterator_tuple(),
other.get_iterator_tuple()
);
}
// Advancing a zip iterator means to advance all iterators in the
// iterator tuple.
void advance(typename super_t::difference_type n)
{
detail::tuple_impl_specific::tuple_for_each(
m_iterator_tuple,
detail::advance_iterator<typename super_t::difference_type>(n)
);
}
// Incrementing a zip iterator means to increment all iterators in
// the iterator tuple.
void increment()
{
detail::tuple_impl_specific::tuple_for_each(
m_iterator_tuple,
detail::increment_iterator()
);
}
// Decrementing a zip iterator means to decrement all iterators in
// the iterator tuple.
void decrement()
{
detail::tuple_impl_specific::tuple_for_each(
m_iterator_tuple,
detail::decrement_iterator()
);
}
// Distance is calculated using the first iterator in the tuple.
template<typename OtherIteratorTuple>
typename super_t::difference_type distance_to(
const zip_iterator<OtherIteratorTuple>& other
) const
{
return boost::tuples::get<0>(other.get_iterator_tuple()) -
boost::tuples::get<0>(this->get_iterator_tuple());
}
// Data Members
// ============
// The iterator tuple.
IteratorTuple m_iterator_tuple;
};
// Make function for zip iterator
//
template<typename IteratorTuple>
zip_iterator<IteratorTuple>
make_zip_iterator(IteratorTuple t)
{ return zip_iterator<IteratorTuple>(t); }
}
#endif