00001 #ifndef UTILMM_ITERATOR_SEQUENCE_HPP
00002 #define UTILMM_ITERATOR_SEQUENCE_HPP
00003
00004 #include <boost/iterator/iterator_facade.hpp>
00005 #include <boost/iterator/iterator_traits.hpp>
00006
00007 namespace utilmm {
00013 template<typename It1, typename It2>
00014 class iterator_sequence :
00015 public boost::iterator_facade<
00016 iterator_sequence<It1, It2>,
00017 typename It1::value_type,
00018 typename boost::iterator_traversal<It1>::type,
00019 typename It1::reference >
00020 {
00021 typedef iterator_sequence<It1, It2> Self;
00022
00023 public:
00036 iterator_sequence(
00037 It1 first, It1 first_end,
00038 It2 second_begin, It2 second)
00039 : m_first(first), m_first_end(first_end)
00040 , m_second_begin(second_begin), m_second(second) {}
00041 iterator_sequence() {}
00042
00043 private:
00044 friend class boost::iterator_core_access;
00045
00046 It1 m_first, m_first_end;
00047 It2 m_second_begin, m_second;
00048
00049 typename Self::reference dereference() const
00050 {
00051 if (m_first == m_first_end)
00052 return *m_second;
00053 else
00054 return *m_first;
00055 }
00056 bool equal(Self x) const
00057 { return (x.m_first == m_first && x.m_second == m_second); }
00058 void increment()
00059 {
00060 if (m_first == m_first_end)
00061 ++m_second;
00062 else
00063 ++m_first;
00064 }
00065 void decrement()
00066 {
00067 if (m_second == m_second_begin)
00068 --m_first;
00069 else
00070 --m_second;
00071 }
00072 void advance(typename Self::difference_type i)
00073 {
00074 if (i > 0)
00075 {
00076 typename Self::difference_type remains = m_first_end - m_first;
00077 if (remains > i)
00078 m_first += i;
00079 else
00080 {
00081 m_first = m_first_end;
00082 m_second += i - remains;
00083 }
00084 }
00085 else
00086 {
00087 typename Self::difference_type remains = m_second_begin - m_second;
00088 if (remains < i)
00089 m_second += i;
00090 else
00091 {
00092 m_second = m_second_begin;
00093 m_first += i - remains;
00094 }
00095 }
00096 }
00097
00098 typename Self::difference_type distance_to(Self x) const
00099 { return (x.m_first - m_first) + (x.m_second - m_second); }
00100 };
00101 }
00102 #endif
