// Boost.Geometry (aka GGL, Generic Geometry Library)
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// Copyright (c) 2014-2020, Oracle and/or its affiliates.
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// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
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// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
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// Licensed under the Boost Software License version 1.0.
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// http://www.boost.org/users/license.html
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#ifndef BOOST_GEOMETRY_ITERATORS_FLATTEN_ITERATOR_HPP
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#define BOOST_GEOMETRY_ITERATORS_FLATTEN_ITERATOR_HPP
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#include <type_traits>
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#include <boost/iterator/iterator_facade.hpp>
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#include <boost/iterator/iterator_categories.hpp>
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#include <boost/geometry/core/assert.hpp>
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#include <boost/geometry/core/static_assert.hpp>
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namespace boost { namespace geometry
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{
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template
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<
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typename OuterIterator,
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typename InnerIterator,
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typename Value,
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typename AccessInnerBegin,
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typename AccessInnerEnd,
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typename Reference = Value&
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>
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class flatten_iterator
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: public boost::iterator_facade
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<
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flatten_iterator
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<
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OuterIterator,
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InnerIterator,
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Value,
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AccessInnerBegin,
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AccessInnerEnd,
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Reference
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>,
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Value,
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boost::bidirectional_traversal_tag,
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Reference
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>
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{
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private:
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OuterIterator m_outer_it, m_outer_end;
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InnerIterator m_inner_it;
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public:
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typedef OuterIterator outer_iterator_type;
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typedef InnerIterator inner_iterator_type;
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// default constructor
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flatten_iterator() {}
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// for begin
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flatten_iterator(OuterIterator outer_it, OuterIterator outer_end)
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: m_outer_it(outer_it), m_outer_end(outer_end)
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{
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advance_through_empty();
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}
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// for end
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flatten_iterator(OuterIterator outer_end)
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: m_outer_it(outer_end), m_outer_end(outer_end)
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{}
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template
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<
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typename OtherOuterIterator, typename OtherInnerIterator,
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typename OtherValue,
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typename OtherAccessInnerBegin, typename OtherAccessInnerEnd,
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typename OtherReference
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>
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flatten_iterator(flatten_iterator
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<
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OtherOuterIterator,
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OtherInnerIterator,
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OtherValue,
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OtherAccessInnerBegin,
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OtherAccessInnerEnd,
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OtherReference
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> const& other)
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: m_outer_it(other.m_outer_it),
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m_outer_end(other.m_outer_end),
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m_inner_it(other.m_inner_it)
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{
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static const bool are_conv
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= std::is_convertible
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<
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OtherOuterIterator, OuterIterator
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>::value
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&& std::is_convertible
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<
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OtherInnerIterator, InnerIterator
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>::value;
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BOOST_GEOMETRY_STATIC_ASSERT((are_conv),
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"Other iterators have to be convertible to member iterators.",
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OtherOuterIterator, OtherInnerIterator);
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}
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flatten_iterator& operator=(flatten_iterator const& other)
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{
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m_outer_it = other.m_outer_it;
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m_outer_end = other.m_outer_end;
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// avoid assigning an iterator having singular value
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if ( other.m_outer_it != other.m_outer_end )
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{
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m_inner_it = other.m_inner_it;
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}
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return *this;
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}
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private:
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friend class boost::iterator_core_access;
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template
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<
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typename Outer,
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typename Inner,
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typename V,
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typename InnerBegin,
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typename InnerEnd,
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typename R
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>
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friend class flatten_iterator;
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static inline bool empty(OuterIterator outer_it)
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{
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return AccessInnerBegin::apply(*outer_it)
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== AccessInnerEnd::apply(*outer_it);
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}
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inline void advance_through_empty()
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{
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while ( m_outer_it != m_outer_end && empty(m_outer_it) )
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{
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++m_outer_it;
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}
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if ( m_outer_it != m_outer_end )
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{
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m_inner_it = AccessInnerBegin::apply(*m_outer_it);
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}
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}
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inline Reference dereference() const
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{
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BOOST_GEOMETRY_ASSERT( m_outer_it != m_outer_end );
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BOOST_GEOMETRY_ASSERT( m_inner_it != AccessInnerEnd::apply(*m_outer_it) );
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return *m_inner_it;
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}
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template
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<
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typename OtherOuterIterator,
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typename OtherInnerIterator,
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typename OtherValue,
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typename OtherAccessInnerBegin,
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typename OtherAccessInnerEnd,
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typename OtherReference
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>
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inline bool equal(flatten_iterator
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<
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OtherOuterIterator,
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OtherInnerIterator,
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OtherValue,
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OtherAccessInnerBegin,
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OtherAccessInnerEnd,
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OtherReference
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> const& other) const
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{
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if ( m_outer_it != other.m_outer_it )
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{
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return false;
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}
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if ( m_outer_it == m_outer_end )
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{
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return true;
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}
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return m_inner_it == other.m_inner_it;
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}
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inline void increment()
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{
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BOOST_GEOMETRY_ASSERT( m_outer_it != m_outer_end );
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BOOST_GEOMETRY_ASSERT( m_inner_it != AccessInnerEnd::apply(*m_outer_it) );
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++m_inner_it;
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if ( m_inner_it == AccessInnerEnd::apply(*m_outer_it) )
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{
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++m_outer_it;
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advance_through_empty();
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}
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}
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inline void decrement()
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{
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if ( m_outer_it == m_outer_end
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|| m_inner_it == AccessInnerBegin::apply(*m_outer_it) )
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{
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do
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{
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--m_outer_it;
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}
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while ( empty(m_outer_it) );
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m_inner_it = AccessInnerEnd::apply(*m_outer_it);
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}
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--m_inner_it;
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}
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};
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_ITERATORS_FLATTEN_ITERATOR_HPP
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