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// Copyright David Abrahams 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 ITERATOR_DWA2002510_HPP
# define ITERATOR_DWA2002510_HPP
# include <boost/python/detail/prefix.hpp>
# include <boost/python/detail/type_traits.hpp>
# include <boost/python/class.hpp>
# include <boost/python/return_value_policy.hpp>
# include <boost/python/return_by_value.hpp>
# include <boost/python/handle.hpp>
# include <boost/python/make_function.hpp>
# include <boost/python/object/iterator_core.hpp>
# include <boost/python/object/class_detail.hpp>
# include <boost/python/object/function_object.hpp>
# include <boost/mpl/vector/vector10.hpp>
# include <boost/mpl/if.hpp>
# include <boost/python/detail/raw_pyobject.hpp>
# include <boost/type.hpp>
# include <boost/detail/iterator.hpp>
namespace boost { namespace python { namespace objects {
// CallPolicies for the next() method of iterators. We don't want
// users to have to explicitly specify that the references returned by
// iterators are copied, so we just replace the result_converter from
// the default_iterator_call_policies with a permissive one which
// always copies the result.
typedef return_value_policy<return_by_value> default_iterator_call_policies;
// Instantiations of these are wrapped to produce Python iterators.
template <class NextPolicies, class Iterator>
struct iterator_range
{
iterator_range(object sequence, Iterator start, Iterator finish);
typedef boost::detail::iterator_traits<Iterator> traits_t;
struct next
{
typedef typename mpl::if_<
is_reference<
typename traits_t::reference
>
, typename traits_t::reference
, typename traits_t::value_type
>::type result_type;
result_type
operator()(iterator_range<NextPolicies,Iterator>& self)
{
if (self.m_start == self.m_finish)
stop_iteration_error();
return *self.m_start++;
}
# if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
// CWPro8 has a codegen problem when this is an empty class
int garbage;
# endif
};
typedef next next_fn;
object m_sequence; // Keeps the sequence alive while iterating.
Iterator m_start;
Iterator m_finish;
};
namespace detail
{
// Get a Python class which contains the given iterator and
// policies, creating it if necessary. Requires: NextPolicies is
// default-constructible.
template <class Iterator, class NextPolicies>
object demand_iterator_class(char const* name, Iterator* = 0, NextPolicies const& policies = NextPolicies())
{
typedef iterator_range<NextPolicies,Iterator> range_;
// Check the registry. If one is already registered, return it.
handle<> class_obj(
objects::registered_class_object(python::type_id<range_>()));
if (class_obj.get() != 0)
return object(class_obj);
typedef typename range_::next_fn next_fn;
typedef typename next_fn::result_type result_type;
return class_<range_>(name, no_init)
.def("__iter__", identity_function())
.def(
#if PY_VERSION_HEX >= 0x03000000
"__next__"
#else
"next"
#endif
, make_function(
next_fn()
, policies
, mpl::vector2<result_type,range_&>()
));
}
// A function object which builds an iterator_range.
template <
class Target
, class Iterator
, class Accessor1
, class Accessor2
, class NextPolicies
>
struct py_iter_
{
py_iter_(Accessor1 const& get_start, Accessor2 const& get_finish)
: m_get_start(get_start)
, m_get_finish(get_finish)
{}
// Extract an object x of the Target type from the first Python
// argument, and invoke get_start(x)/get_finish(x) to produce
// iterators, which are used to construct a new iterator_range<>
// object that gets wrapped into a Python iterator.
iterator_range<NextPolicies,Iterator>
operator()(back_reference<Target&> x) const
{
// Make sure the Python class is instantiated.
detail::demand_iterator_class("iterator", (Iterator*)0, NextPolicies());
return iterator_range<NextPolicies,Iterator>(
x.source()
, m_get_start(x.get())
, m_get_finish(x.get())
);
}
private:
Accessor1 m_get_start;
Accessor2 m_get_finish;
};
template <class Target, class Iterator, class NextPolicies, class Accessor1, class Accessor2>
inline object make_iterator_function(
Accessor1 const& get_start
, Accessor2 const& get_finish
, NextPolicies const& /*next_policies*/
, Iterator const& (*)()
, boost::type<Target>*
, int
)
{
return make_function(
py_iter_<Target,Iterator,Accessor1,Accessor2,NextPolicies>(get_start, get_finish)
, default_call_policies()
, mpl::vector2<iterator_range<NextPolicies,Iterator>, back_reference<Target&> >()
);
}
template <class Target, class Iterator, class NextPolicies, class Accessor1, class Accessor2>
inline object make_iterator_function(
Accessor1 const& get_start
, Accessor2 const& get_finish
, NextPolicies const& next_policies
, Iterator& (*)()
, boost::type<Target>*
, ...)
{
return make_iterator_function(
get_start
, get_finish
, next_policies
, (Iterator const&(*)())0
, (boost::type<Target>*)0
, 0
);
}
}
// Create a Python callable object which accepts a single argument
// convertible to the C++ Target type and returns a Python
// iterator. The Python iterator uses get_start(x) and get_finish(x)
// (where x is an instance of Target) to produce begin and end
// iterators for the range, and an instance of NextPolicies is used as
// CallPolicies for the Python iterator's next() function.
template <class Target, class NextPolicies, class Accessor1, class Accessor2>
inline object make_iterator_function(
Accessor1 const& get_start
, Accessor2 const& get_finish
, NextPolicies const& next_policies
, boost::type<Target>* = 0
)
{
typedef typename Accessor1::result_type iterator;
typedef typename boost::python::detail::add_const<iterator>::type iterator_const;
typedef typename boost::python::detail::add_lvalue_reference<iterator_const>::type iterator_cref;
return detail::make_iterator_function(
get_start
, get_finish
, next_policies
, (iterator_cref(*)())0
, (boost::type<Target>*)0
, 0
);
}
//
// implementation
//
template <class NextPolicies, class Iterator>
inline iterator_range<NextPolicies,Iterator>::iterator_range(
object sequence, Iterator start, Iterator finish)
: m_sequence(sequence), m_start(start), m_finish(finish)
{
}
}}} // namespace boost::python::objects
#endif // ITERATOR_DWA2002510_HPP
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