189 lines
6.0 KiB
C++
189 lines
6.0 KiB
C++
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// (C) Copyright David Abrahams 2002.
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// (C) Copyright Jeremy Siek 2002.
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// (C) Copyright Thomas Witt 2002.
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_TRANSFORM_ITERATOR_23022003THW_HPP
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#define BOOST_TRANSFORM_ITERATOR_23022003THW_HPP
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#include <boost/function.hpp>
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#include <boost/iterator.hpp>
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#include <boost/iterator/detail/enable_if.hpp>
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#include <boost/iterator/iterator_adaptor.hpp>
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#include <boost/iterator/iterator_categories.hpp>
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#include <boost/mpl/not.hpp>
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#include <boost/mpl/bool.hpp>
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#include <boost/type_traits/function_traits.hpp>
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#include <boost/type_traits/is_const.hpp>
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#include <boost/type_traits/is_class.hpp>
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#include <boost/type_traits/is_function.hpp>
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#include <boost/type_traits/is_reference.hpp>
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#include <boost/type_traits/remove_const.hpp>
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#include <boost/type_traits/remove_reference.hpp>
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#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1310))
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# include <boost/type_traits/is_base_and_derived.hpp>
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#endif
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#include <boost/iterator/detail/config_def.hpp>
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namespace boost
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{
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template <class UnaryFunction, class Iterator, class Reference = use_default, class Value = use_default>
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class transform_iterator;
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namespace detail
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{
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template <class UnaryFunc>
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struct function_object_result
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{
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typedef typename UnaryFunc::result_type type;
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};
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#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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template <class Return, class Argument>
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struct function_object_result<Return(*)(Argument)>
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{
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typedef Return type;
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};
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#endif
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// Compute the iterator_adaptor instantiation to be used for transform_iterator
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template <class UnaryFunc, class Iterator, class Reference, class Value>
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struct transform_iterator_base
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{
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private:
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// By default, dereferencing the iterator yields the same as
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// the function. Do we need to adjust the way
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// function_object_result is computed for the standard
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// proposal (e.g. using Doug's result_of)?
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typedef typename ia_dflt_help<
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Reference
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, function_object_result<UnaryFunc>
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>::type reference;
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// To get the default for Value: remove any reference on the
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// result type, but retain any constness to signal
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// non-writability. Note that if we adopt Thomas' suggestion
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// to key non-writability *only* on the Reference argument,
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// we'd need to strip constness here as well.
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typedef typename ia_dflt_help<
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Value
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, remove_reference<reference>
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>::type cv_value_type;
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public:
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typedef iterator_adaptor<
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transform_iterator<UnaryFunc, Iterator, Reference, Value>
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, Iterator
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, cv_value_type
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, use_default // Leave the traversal category alone
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, reference
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> type;
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};
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}
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template <class UnaryFunc, class Iterator, class Reference, class Value>
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class transform_iterator
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: public boost::detail::transform_iterator_base<UnaryFunc, Iterator, Reference, Value>::type
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{
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typedef typename
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boost::detail::transform_iterator_base<UnaryFunc, Iterator, Reference, Value>::type
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super_t;
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friend class iterator_core_access;
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public:
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transform_iterator() { }
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transform_iterator(Iterator const& x, UnaryFunc f)
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: super_t(x), m_f(f) { }
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explicit transform_iterator(Iterator const& x)
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: super_t(x)
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{
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// Pro8 is a little too aggressive about instantiating the
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// body of this function.
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#if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
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// don't provide this constructor if UnaryFunc is a
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// function pointer type, since it will be 0. Too dangerous.
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BOOST_STATIC_ASSERT(is_class<UnaryFunc>::value);
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#endif
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}
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template<
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class OtherUnaryFunction
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, class OtherIterator
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, class OtherReference
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, class OtherValue>
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transform_iterator(
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transform_iterator<OtherUnaryFunction, OtherIterator, OtherReference, OtherValue> const& t
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, typename enable_if_convertible<OtherIterator, Iterator>::type* = 0
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#if !BOOST_WORKAROUND(BOOST_MSVC, == 1310)
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, typename enable_if_convertible<OtherUnaryFunction, UnaryFunc>::type* = 0
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#endif
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)
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: super_t(t.base()), m_f(t.functor())
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{}
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UnaryFunc functor() const
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{ return m_f; }
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private:
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typename super_t::reference dereference() const
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{ return m_f(*this->base()); }
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// Probably should be the initial base class so it can be
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// optimized away via EBO if it is an empty class.
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UnaryFunc m_f;
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};
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template <class UnaryFunc, class Iterator>
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transform_iterator<UnaryFunc, Iterator>
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make_transform_iterator(Iterator it, UnaryFunc fun)
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{
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return transform_iterator<UnaryFunc, Iterator>(it, fun);
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}
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// Version which allows explicit specification of the UnaryFunc
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// type.
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//
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// This generator is not provided if UnaryFunc is a function
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// pointer type, because it's too dangerous: the default-constructed
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// function pointer in the iterator be 0, leading to a runtime
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// crash.
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template <class UnaryFunc, class Iterator>
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#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
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typename mpl::if_<
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#else
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typename iterators::enable_if<
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#endif
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is_class<UnaryFunc> // We should probably find a cheaper test than is_class<>
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, transform_iterator<UnaryFunc, Iterator>
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#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
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, int[3]
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#endif
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>::type
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make_transform_iterator(Iterator it)
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{
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return transform_iterator<UnaryFunc, Iterator>(it, UnaryFunc());
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}
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#if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION ) && !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
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template <class Return, class Argument, class Iterator>
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transform_iterator< Return (*)(Argument), Iterator, Return>
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make_transform_iterator(Iterator it, Return (*fun)(Argument))
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{
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return transform_iterator<Return (*)(Argument), Iterator, Return>(it, fun);
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}
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#endif
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} // namespace boost
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#include <boost/iterator/detail/config_undef.hpp>
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#endif // BOOST_TRANSFORM_ITERATOR_23022003THW_HPP
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