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Reimplement zip_iterator based on Boost.Fusion

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By default, backward compatibility for Boost.Tuple is presented.

Signed-off-by: Kohei Takahashi <flast@flast.jp>
This commit is contained in:
Kohei Takahashi
2012-10-17 18:09:08 +09:00
parent 0e23f15623
commit acf9b4d4cf
1 changed files with 94 additions and 347 deletions
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441
include/boost/iterator/zip_iterator.hpp
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@ -1,6 +1,8 @@
// Copyright David Abrahams and Thomas Becker 2000-2006. Distributed // Copyright David Abrahams and Thomas Becker 2000-2006.
// under the Boost Software License, Version 1.0. (See accompanying // Copyright Kohei Takahashi 2012-2014.
// file LICENSE_1_0.txt or copy at //
// 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) // http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_ZIP_ITERATOR_TMB_07_13_2003_HPP_ #ifndef BOOST_ZIP_ITERATOR_TMB_07_13_2003_HPP_
@ -16,40 +18,30 @@
#include <boost/iterator/detail/minimum_category.hpp> #include <boost/iterator/detail/minimum_category.hpp>
#include <boost/tuple/tuple.hpp> #include <boost/fusion/adapted/boost_tuple.hpp> // for backward compatibility
#include <boost/type_traits/is_same.hpp> #include <boost/type_traits/remove_reference.hpp>
#include <boost/mpl/and.hpp> #include <boost/type_traits/remove_cv.hpp>
#include <boost/mpl/apply.hpp>
#include <boost/mpl/eval_if.hpp> #include <boost/mpl/at.hpp>
#include <boost/mpl/lambda.hpp> #include <boost/mpl/fold.hpp>
#include <boost/mpl/transform.hpp>
#include <boost/mpl/placeholders.hpp> #include <boost/mpl/placeholders.hpp>
#include <boost/mpl/aux_/lambda_support.hpp> #include <boost/mpl/aux_/lambda_support.hpp>
#include <boost/fusion/algorithm/iteration/for_each.hpp>
#include <boost/fusion/algorithm/transformation/transform.hpp>
#include <boost/fusion/sequence/convert.hpp>
#include <boost/fusion/sequence/intrinsic/at_c.hpp>
#include <boost/fusion/sequence/comparison/equal_to.hpp>
#include <boost/fusion/support/tag_of_fwd.hpp>
namespace boost { namespace boost {
// Zip iterator forward declaration for zip_iterator_base // Zip iterator forward declaration for zip_iterator_base
template<typename IteratorTuple> template<typename IteratorTuple>
class zip_iterator; 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.
namespace detail namespace detail
{ {
@ -60,7 +52,7 @@ namespace boost {
{ {
public: public:
advance_iterator(DiffType step) : m_step(step) {} advance_iterator(DiffType step) : m_step(step) {}
template<typename Iterator> template<typename Iterator>
void operator()(Iterator& it) const void operator()(Iterator& it) const
{ it += m_step; } { it += m_step; }
@ -72,250 +64,39 @@ namespace boost {
struct increment_iterator struct increment_iterator
{ {
template<typename Iterator> template<typename Iterator>
void operator()(Iterator& it) void operator()(Iterator& it) const
{ ++it; } { ++it; }
}; };
// //
struct decrement_iterator struct decrement_iterator
{ {
template<typename Iterator> template<typename Iterator>
void operator()(Iterator& it) void operator()(Iterator& it) const
{ --it; } { --it; }
}; };
// //
struct dereference_iterator struct dereference_iterator
{ {
template<typename Iterator> template<typename>
struct apply struct result;
{
template<typename This, typename Iterator>
struct result<This(Iterator)>
{
typedef typename typedef typename
iterator_traits<Iterator>::reference remove_reference<typename remove_cv<Iterator>::type>::type
iterator;
typedef typename
iterator_traits<iterator>::reference
type; type;
}; };
template<typename Iterator> template<typename Iterator>
typename apply<Iterator>::type operator()(Iterator const& it) typename result<dereference_iterator(Iterator)>::type
operator()(Iterator const& it) const
{ return *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::eval_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::eval_if<
#if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
mpl::or_<
#endif
boost::is_same<Tuple, tuples::null_type>
#if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
, 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<
BOOST_DEDUCED_TYPENAME Tuple::tail_type
, Fun
>::type transformed_tail_type;
return tuples::cons<
BOOST_DEDUCED_TYPENAME mpl::apply1<
Fun, BOOST_DEDUCED_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.
//
inline 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> template<typename Iterator>
struct iterator_reference struct iterator_reference
@ -336,14 +117,14 @@ namespace boost {
struct apply : iterator_reference<T> {}; struct apply : iterator_reference<T> {};
}; };
#endif #endif
// Metafunction to obtain the type of the tuple whose element types // Metafunction to obtain the type of the tuple whose element types
// are the reference types of an iterator tuple. // are the reference types of an iterator tuple.
// //
template<typename IteratorTuple> template<typename IteratorTuple>
struct tuple_of_references struct tuple_of_references
: tuple_impl_specific::tuple_meta_transform< : mpl::transform<
IteratorTuple, IteratorTuple,
iterator_reference<mpl::_1> iterator_reference<mpl::_1>
> >
{ {
@ -355,54 +136,23 @@ namespace boost {
template<typename IteratorTuple> template<typename IteratorTuple>
struct minimum_traversal_category_in_iterator_tuple struct minimum_traversal_category_in_iterator_tuple
{ {
typedef typename tuple_impl_specific::tuple_meta_transform< typedef typename mpl::transform<
IteratorTuple IteratorTuple
, pure_traversal_tag<iterator_traversal<> > , pure_traversal_tag<iterator_traversal<> >
>::type tuple_of_traversal_tags; >::type tuple_of_traversal_tags;
typedef typename tuple_impl_specific::tuple_meta_accumulate< typedef typename mpl::fold<
tuple_of_traversal_tags tuple_of_traversal_tags
, minimum_category<>
, random_access_traversal_tag , random_access_traversal_tag
, minimum_category<>
>::type type; >::type type;
}; };
#if BOOST_WORKAROUND(BOOST_MSVC, < 1300) // ETI workaround
template <>
struct minimum_traversal_category_in_iterator_tuple<int>
{
typedef int type;
};
#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_CFG_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
/////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////
// //
// Class zip_iterator_base // Class zip_iterator_base
// //
// Builds and exposes the iterator facade type from which the zip // Builds and exposes the iterator facade type from which the zip
// iterator will be derived. // iterator will be derived.
// //
template<typename IteratorTuple> template<typename IteratorTuple>
@ -411,30 +161,30 @@ namespace boost {
private: private:
// Reference type is the type of the tuple obtained from the // Reference type is the type of the tuple obtained from the
// iterators' reference types. // iterators' reference types.
typedef typename typedef typename
detail::tuple_of_references<IteratorTuple>::type reference; detail::tuple_of_references<IteratorTuple>::type reference;
// Value type is the same as reference type. // Value type is the same as reference type.
typedef reference value_type; typedef reference value_type;
// Difference type is the first iterator's difference type // Difference type is the first iterator's difference type
typedef typename iterator_traits< typedef typename iterator_traits<
typename tuples::element<0, IteratorTuple>::type typename mpl::at_c<IteratorTuple, 0>::type
>::difference_type difference_type; >::difference_type difference_type;
// Traversal catetgory is the minimum traversal category in the // Traversal catetgory is the minimum traversal category in the
// iterator tuple. // iterator tuple.
typedef typename typedef typename
detail::minimum_traversal_category_in_iterator_tuple< detail::minimum_traversal_category_in_iterator_tuple<
IteratorTuple IteratorTuple
>::type traversal_category; >::type traversal_category;
public: public:
// The iterator facade type from which the zip iterator will // The iterator facade type from which the zip iterator will
// be derived. // be derived.
typedef iterator_facade< typedef iterator_facade<
zip_iterator<IteratorTuple>, zip_iterator<IteratorTuple>,
value_type, value_type,
traversal_category, traversal_category,
reference, reference,
difference_type difference_type
@ -447,34 +197,34 @@ namespace boost {
typedef int type; typedef int type;
}; };
} }
///////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////
// //
// zip_iterator class definition // zip_iterator class definition
// //
template<typename IteratorTuple> template<typename IteratorTuple>
class zip_iterator : class zip_iterator :
public detail::zip_iterator_base<IteratorTuple>::type public detail::zip_iterator_base<IteratorTuple>::type
{ {
// Typedef super_t as our base class. // Typedef super_t as our base class.
typedef typename typedef typename
detail::zip_iterator_base<IteratorTuple>::type super_t; detail::zip_iterator_base<IteratorTuple>::type super_t;
// iterator_core_access is the iterator's best friend. // iterator_core_access is the iterator's best friend.
friend class iterator_core_access; friend class iterator_core_access;
public: public:
// Construction // Construction
// ============ // ============
// Default constructor // Default constructor
zip_iterator() { } zip_iterator() { }
// Constructor from iterator tuple // Constructor from iterator tuple
zip_iterator(IteratorTuple iterator_tuple) zip_iterator(IteratorTuple iterator_tuple)
: m_iterator_tuple(iterator_tuple) : m_iterator_tuple(iterator_tuple)
{ } { }
// Copy constructor // Copy constructor
@ -493,18 +243,19 @@ namespace boost {
{ return m_iterator_tuple; } { return m_iterator_tuple; }
private: private:
// Implementation of Iterator Operations // Implementation of Iterator Operations
// ===================================== // =====================================
// Dereferencing returns a tuple built from the dereferenced // Dereferencing returns a tuple built from the dereferenced
// iterators in the iterator tuple. // iterators in the iterator tuple.
typename super_t::reference dereference() const typename super_t::reference dereference() const
{ {
return detail::tuple_impl_specific::tuple_transform( typedef typename super_t::reference reference;
get_iterator_tuple(), typedef typename fusion::traits::tag_of<reference>::type tag;
detail::dereference_iterator() return fusion::convert<tag>(fusion::transform(
); get_iterator_tuple(),
detail::dereference_iterator()));
} }
// Two zip iterators are equal if all iterators in the iterator // Two zip iterators are equal if all iterators in the iterator
@ -517,66 +268,62 @@ namespace boost {
// under several compilers. No point in bringing in a bunch // under several compilers. No point in bringing in a bunch
// of #ifdefs here. // of #ifdefs here.
// //
template<typename OtherIteratorTuple> template<typename OtherIteratorTuple>
bool equal(const zip_iterator<OtherIteratorTuple>& other) const bool equal(const zip_iterator<OtherIteratorTuple>& other) const
{ {
return detail::tuple_impl_specific::tuple_equal( return fusion::equal_to(
get_iterator_tuple(), get_iterator_tuple(),
other.get_iterator_tuple() other.get_iterator_tuple());
);
} }
// Advancing a zip iterator means to advance all iterators in the // Advancing a zip iterator means to advance all iterators in the
// iterator tuple. // iterator tuple.
void advance(typename super_t::difference_type n) void advance(typename super_t::difference_type n)
{ {
detail::tuple_impl_specific::tuple_for_each( fusion::for_each(
m_iterator_tuple, m_iterator_tuple,
detail::advance_iterator<BOOST_DEDUCED_TYPENAME super_t::difference_type>(n) detail::advance_iterator<BOOST_DEDUCED_TYPENAME super_t::difference_type>(n));
);
} }
// Incrementing a zip iterator means to increment all iterators in // Incrementing a zip iterator means to increment all iterators in
// the iterator tuple. // the iterator tuple.
void increment() void increment()
{ {
detail::tuple_impl_specific::tuple_for_each( fusion::for_each(
m_iterator_tuple, m_iterator_tuple,
detail::increment_iterator() detail::increment_iterator());
);
} }
// Decrementing a zip iterator means to decrement all iterators in // Decrementing a zip iterator means to decrement all iterators in
// the iterator tuple. // the iterator tuple.
void decrement() void decrement()
{ {
detail::tuple_impl_specific::tuple_for_each( fusion::for_each(
m_iterator_tuple, m_iterator_tuple,
detail::decrement_iterator() detail::decrement_iterator());
);
} }
// Distance is calculated using the first iterator in the tuple. // Distance is calculated using the first iterator in the tuple.
template<typename OtherIteratorTuple> template<typename OtherIteratorTuple>
typename super_t::difference_type distance_to( typename super_t::difference_type distance_to(
const zip_iterator<OtherIteratorTuple>& other const zip_iterator<OtherIteratorTuple>& other
) const ) const
{ {
return boost::tuples::get<0>(other.get_iterator_tuple()) - return fusion::at_c<0>(other.get_iterator_tuple()) -
boost::tuples::get<0>(this->get_iterator_tuple()); fusion::at_c<0>(this->get_iterator_tuple());
} }
// Data Members // Data Members
// ============ // ============
// The iterator tuple. // The iterator tuple.
IteratorTuple m_iterator_tuple; IteratorTuple m_iterator_tuple;
}; };
// Make function for zip iterator // Make function for zip iterator
// //
template<typename IteratorTuple> template<typename IteratorTuple>
zip_iterator<IteratorTuple> zip_iterator<IteratorTuple>
make_zip_iterator(IteratorTuple t) make_zip_iterator(IteratorTuple t)
{ return zip_iterator<IteratorTuple>(t); } { return zip_iterator<IteratorTuple>(t); }