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Copy pathtransform_iterator.hpp
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175 lines (148 loc) · 5.78 KB
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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_TRANSFORM_ITERATOR_23022003THW_HPP
#define BOOST_TRANSFORM_ITERATOR_23022003THW_HPP
#include <boost/iterator/detail/enable_if.hpp>
#include <boost/iterator/iterator_adaptor.hpp>
#include <boost/iterator/iterator_categories.hpp>
#include <boost/mpl/not.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/type_traits/function_traits.hpp>
#include <boost/type_traits/is_const.hpp>
#include <boost/type_traits/is_class.hpp>
#include <boost/type_traits/is_function.hpp>
#include <boost/type_traits/is_reference.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/utility/result_of.hpp>
#include <iterator>
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1310))
# include <boost/type_traits/is_base_and_derived.hpp>
#endif
#include <boost/iterator/detail/config_def.hpp>
namespace boost {
namespace iterators {
template <class UnaryFunction, class Iterator, class Reference = use_default, class Value = use_default>
class transform_iterator;
namespace detail
{
// Compute the iterator_adaptor instantiation to be used for transform_iterator
template <class UnaryFunc, class Iterator, class Reference, class Value>
struct transform_iterator_base
{
private:
// By default, dereferencing the iterator yields the same as
// the function.
typedef typename ia_dflt_help<
Reference
#ifdef BOOST_RESULT_OF_USE_TR1
, result_of<const UnaryFunc(typename std::iterator_traits<Iterator>::reference)>
#else
, result_of<const UnaryFunc&(typename std::iterator_traits<Iterator>::reference)>
#endif
>::type reference;
// To get the default for Value: remove any reference on the
// result type, but retain any constness to signal
// non-writability. Note that if we adopt Thomas' suggestion
// to key non-writability *only* on the Reference argument,
// we'd need to strip constness here as well.
typedef typename ia_dflt_help<
Value
, remove_reference<reference>
>::type cv_value_type;
public:
typedef iterator_adaptor<
transform_iterator<UnaryFunc, Iterator, Reference, Value>
, Iterator
, cv_value_type
, use_default // Leave the traversal category alone
, reference
> type;
};
}
template <class UnaryFunc, class Iterator, class Reference, class Value>
class transform_iterator
: public boost::iterators::detail::transform_iterator_base<UnaryFunc, Iterator, Reference, Value>::type
{
typedef typename
boost::iterators::detail::transform_iterator_base<UnaryFunc, Iterator, Reference, Value>::type
super_t;
friend class iterator_core_access;
public:
transform_iterator() { }
transform_iterator(Iterator const& x, UnaryFunc f)
: super_t(x), m_f(f) { }
explicit transform_iterator(Iterator const& x)
: super_t(x)
{
// Pro8 is a little too aggressive about instantiating the
// body of this function.
#if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
// don't provide this constructor if UnaryFunc is a
// function pointer type, since it will be 0. Too dangerous.
BOOST_STATIC_ASSERT(is_class<UnaryFunc>::value);
#endif
}
template <
class OtherUnaryFunction
, class OtherIterator
, class OtherReference
, class OtherValue>
transform_iterator(
transform_iterator<OtherUnaryFunction, OtherIterator, OtherReference, OtherValue> const& t
, typename enable_if_convertible<OtherIterator, Iterator>::type* = 0
#if !BOOST_WORKAROUND(BOOST_MSVC, == 1310)
, typename enable_if_convertible<OtherUnaryFunction, UnaryFunc>::type* = 0
#endif
)
: super_t(t.base()), m_f(t.functor())
{}
UnaryFunc functor() const
{ return m_f; }
private:
typename super_t::reference dereference() const
{ return m_f(*this->base()); }
// Probably should be the initial base class so it can be
// optimized away via EBO if it is an empty class.
UnaryFunc m_f;
};
template <class UnaryFunc, class Iterator>
inline transform_iterator<UnaryFunc, Iterator>
make_transform_iterator(Iterator it, UnaryFunc fun)
{
return transform_iterator<UnaryFunc, Iterator>(it, fun);
}
// Version which allows explicit specification of the UnaryFunc
// type.
//
// This generator is not provided if UnaryFunc is a function
// pointer type, because it's too dangerous: the default-constructed
// function pointer in the iterator be 0, leading to a runtime
// crash.
template <class UnaryFunc, class Iterator>
inline typename iterators::enable_if<
is_class<UnaryFunc> // We should probably find a cheaper test than is_class<>
, transform_iterator<UnaryFunc, Iterator>
>::type
make_transform_iterator(Iterator it)
{
return transform_iterator<UnaryFunc, Iterator>(it, UnaryFunc());
}
#if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION ) && !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
template <class Return, class Argument, class Iterator>
inline transform_iterator< Return (*)(Argument), Iterator, Return>
make_transform_iterator(Iterator it, Return (*fun)(Argument))
{
return transform_iterator<Return (*)(Argument), Iterator, Return>(it, fun);
}
#endif
} // namespace iterators
using iterators::transform_iterator;
using iterators::make_transform_iterator;
} // namespace boost
#include <boost/iterator/detail/config_undef.hpp>
#endif // BOOST_TRANSFORM_ITERATOR_23022003THW_HPP