355 lines
11 KiB
Plaintext
355 lines
11 KiB
Plaintext
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// Boost.Range library
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//
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// Copyright Neil Groves 2009. Use, modification and
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// distribution is subject to the Boost Software License, Version
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// 1.0. (See 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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//
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// Acknowledgements:
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// aschoedl contributed an improvement to the determination
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// of the Reference type parameter.
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//
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// Leonid Gershanovich reported Trac ticket 7376 about the dereference operator
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// requiring identical reference types due to using the ternary if.
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//
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// For more information, see http://www.boost.org/libs/range/
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//
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#ifndef BOOST_RANGE_DETAIL_JOIN_ITERATOR_HPP_INCLUDED
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#define BOOST_RANGE_DETAIL_JOIN_ITERATOR_HPP_INCLUDED
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#include <iterator>
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#include <boost/assert.hpp>
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#include <boost/iterator/iterator_traits.hpp>
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#include <boost/iterator/iterator_facade.hpp>
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#include <boost/range/begin.hpp>
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#include <boost/range/end.hpp>
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#include <boost/range/empty.hpp>
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#include <boost/range/detail/demote_iterator_traversal_tag.hpp>
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#include <boost/range/value_type.hpp>
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#include <boost/type_traits/add_const.hpp>
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#include <boost/type_traits/add_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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#include <boost/next_prior.hpp>
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namespace boost
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{
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namespace range_detail
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{
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template<typename Iterator1, typename Iterator2>
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struct join_iterator_link
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{
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public:
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join_iterator_link(Iterator1 last1, Iterator2 first2)
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: last1(last1)
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, first2(first2)
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{
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}
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Iterator1 last1;
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Iterator2 first2;
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private:
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join_iterator_link() /* = delete */ ;
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};
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class join_iterator_begin_tag {};
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class join_iterator_end_tag {};
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template<typename Iterator1
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, typename Iterator2
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, typename Reference
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>
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class join_iterator_union
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{
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public:
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typedef Iterator1 iterator1_t;
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typedef Iterator2 iterator2_t;
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join_iterator_union() {}
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join_iterator_union(unsigned int /*selected*/, const iterator1_t& it1, const iterator2_t& it2) : m_it1(it1), m_it2(it2) {}
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iterator1_t& it1() { return m_it1; }
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const iterator1_t& it1() const { return m_it1; }
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iterator2_t& it2() { return m_it2; }
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const iterator2_t& it2() const { return m_it2; }
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Reference dereference(unsigned int selected) const
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{
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if (selected)
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return *m_it2;
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return *m_it1;
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}
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bool equal(const join_iterator_union& other, unsigned int selected) const
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{
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return selected
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? m_it2 == other.m_it2
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: m_it1 == other.m_it1;
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}
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private:
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iterator1_t m_it1;
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iterator2_t m_it2;
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};
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template<class Iterator, class Reference>
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class join_iterator_union<Iterator, Iterator, Reference>
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{
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public:
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typedef Iterator iterator1_t;
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typedef Iterator iterator2_t;
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join_iterator_union() {}
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join_iterator_union(unsigned int selected, const iterator1_t& it1, const iterator2_t& it2)
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: m_it(selected ? it2 : it1)
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{
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}
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iterator1_t& it1() { return m_it; }
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const iterator1_t& it1() const { return m_it; }
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iterator2_t& it2() { return m_it; }
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const iterator2_t& it2() const { return m_it; }
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Reference dereference(unsigned int) const
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{
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return *m_it;
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}
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bool equal(const join_iterator_union& other,
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unsigned int /*selected*/) const
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{
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return m_it == other.m_it;
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}
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private:
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iterator1_t m_it;
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};
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template<typename Iterator1
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, typename Iterator2
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, typename ValueType = typename iterator_value<Iterator1>::type
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// find least demanding, commonly supported reference type, in the order &, const&, and by-value:
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, typename Reference = typename mpl::if_c<
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!is_reference<typename iterator_reference<Iterator1>::type>::value
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|| !is_reference<typename iterator_reference<Iterator2>::type>::value,
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typename remove_const<
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typename remove_reference<
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typename iterator_reference<Iterator1>::type
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>::type
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>::type,
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typename mpl::if_c<
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is_const<
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typename remove_reference<
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typename iterator_reference<Iterator1>::type
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>::type
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>::value
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|| is_const<
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typename remove_reference<
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typename iterator_reference<Iterator2>::type
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>::type
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>::value,
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typename add_const<
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typename iterator_reference<Iterator1>::type
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>::type,
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typename iterator_reference<Iterator1>::type
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>::type
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>::type
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, typename Traversal = typename demote_iterator_traversal_tag<
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typename iterator_traversal<Iterator1>::type
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, typename iterator_traversal<Iterator2>::type>::type
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>
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class join_iterator
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: public iterator_facade<join_iterator<Iterator1,Iterator2,ValueType,Reference,Traversal>, ValueType, Traversal, Reference>
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{
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typedef join_iterator_link<Iterator1, Iterator2> link_t;
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typedef join_iterator_union<Iterator1, Iterator2, Reference> iterator_union;
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public:
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typedef Iterator1 iterator1_t;
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typedef Iterator2 iterator2_t;
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join_iterator()
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: m_section(0u)
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, m_it(0u, iterator1_t(), iterator2_t())
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, m_link(link_t(iterator1_t(), iterator2_t()))
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{}
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join_iterator(unsigned int section, Iterator1 current1, Iterator1 last1, Iterator2 first2, Iterator2 current2)
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: m_section(section)
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, m_it(section, current1, current2)
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, m_link(link_t(last1, first2))
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{
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}
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template<typename Range1, typename Range2>
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join_iterator(Range1& r1, Range2& r2, join_iterator_begin_tag)
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: m_section(boost::empty(r1) ? 1u : 0u)
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, m_it(boost::empty(r1) ? 1u : 0u, boost::begin(r1), boost::begin(r2))
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, m_link(link_t(boost::end(r1), boost::begin(r2)))
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{
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}
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template<typename Range1, typename Range2>
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join_iterator(const Range1& r1, const Range2& r2, join_iterator_begin_tag)
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: m_section(boost::empty(r1) ? 1u : 0u)
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, m_it(boost::empty(r1) ? 1u : 0u, boost::const_begin(r1), boost::const_begin(r2))
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, m_link(link_t(boost::const_end(r1), boost::const_begin(r2)))
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{
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}
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template<typename Range1, typename Range2>
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join_iterator(Range1& r1, Range2& r2, join_iterator_end_tag)
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: m_section(1u)
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, m_it(1u, boost::end(r1), boost::end(r2))
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, m_link(link_t(boost::end(r1), boost::begin(r2)))
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{
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}
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template<typename Range1, typename Range2>
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join_iterator(const Range1& r1, const Range2& r2, join_iterator_end_tag)
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: m_section(1u)
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, m_it(1u, boost::const_end(r1), boost::const_end(r2))
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, m_link(link_t(boost::const_end(r1), boost::const_begin(r2)))
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{
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}
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private:
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void increment()
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{
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if (m_section)
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++m_it.it2();
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else
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{
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++m_it.it1();
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if (m_it.it1() == m_link.last1)
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{
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m_it.it2() = m_link.first2;
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m_section = 1u;
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}
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}
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}
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void decrement()
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{
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if (m_section)
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{
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if (m_it.it2() == m_link.first2)
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{
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m_it.it1() = boost::prior(m_link.last1);
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m_section = 0u;
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}
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else
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--m_it.it2();
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}
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else
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--m_it.it1();
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}
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typename join_iterator::reference dereference() const
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{
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return m_it.dereference(m_section);
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}
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bool equal(const join_iterator& other) const
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{
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return m_section == other.m_section
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&& m_it.equal(other.m_it, m_section);
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}
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void advance(typename join_iterator::difference_type offset)
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{
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if (m_section)
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advance_from_range2(offset);
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else
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advance_from_range1(offset);
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}
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typename join_iterator::difference_type distance_to(const join_iterator& other) const
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{
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typename join_iterator::difference_type result;
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if (m_section)
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{
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if (other.m_section)
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result = other.m_it.it2() - m_it.it2();
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else
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{
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result = (m_link.first2 - m_it.it2())
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+ (other.m_it.it1() - m_link.last1);
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BOOST_ASSERT( result <= 0 );
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}
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}
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else
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{
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if (other.m_section)
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{
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result = (m_link.last1 - m_it.it1())
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+ (other.m_it.it2() - m_link.first2);
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}
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else
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result = other.m_it.it1() - m_it.it1();
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}
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return result;
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}
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void advance_from_range2(typename join_iterator::difference_type offset)
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{
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typedef typename join_iterator::difference_type difference_t;
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BOOST_ASSERT( m_section == 1u );
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if (offset < 0)
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{
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difference_t r2_dist = m_link.first2 - m_it.it2();
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BOOST_ASSERT( r2_dist <= 0 );
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if (offset >= r2_dist)
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std::advance(m_it.it2(), offset);
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else
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{
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difference_t r1_dist = offset - r2_dist;
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BOOST_ASSERT( r1_dist <= 0 );
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m_it.it1() = m_link.last1 + r1_dist;
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m_section = 0u;
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}
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}
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else
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std::advance(m_it.it2(), offset);
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}
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void advance_from_range1(typename join_iterator::difference_type offset)
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{
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typedef typename join_iterator::difference_type difference_t;
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BOOST_ASSERT( m_section == 0u );
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if (offset > 0)
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{
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difference_t r1_dist = m_link.last1 - m_it.it1();
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BOOST_ASSERT( r1_dist >= 0 );
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if (offset < r1_dist)
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std::advance(m_it.it1(), offset);
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else
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{
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difference_t r2_dist = offset - r1_dist;
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BOOST_ASSERT( r2_dist >= 0 );
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m_it.it2() = m_link.first2 + r2_dist;
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m_section = 1u;
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}
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}
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else
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std::advance(m_it.it1(), offset);
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}
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unsigned int m_section;
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iterator_union m_it;
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link_t m_link;
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friend class ::boost::iterator_core_access;
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};
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} // namespace range_detail
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} // namespace boost
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#endif // include guard
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