transform_iterator.hpp 5.1 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176
  1. //////////////////////////////////////////////////////////////////////////////
  2. //
  3. // (C) Copyright Ion Gaztanaga 2005-2012.
  4. // (C) Copyright Gennaro Prota 2003 - 2004.
  5. //
  6. // Distributed under the Boost Software License, Version 1.0.
  7. // (See accompanying file LICENSE_1_0.txt or copy at
  8. // http://www.boost.org/LICENSE_1_0.txt)
  9. //
  10. // See http://www.boost.org/libs/container for documentation.
  11. //
  12. //////////////////////////////////////////////////////////////////////////////
  13. #ifndef BOOST_CONTAINER_DETAIL_TRANSFORM_ITERATORS_HPP
  14. #define BOOST_CONTAINER_DETAIL_TRANSFORM_ITERATORS_HPP
  15. #if defined(_MSC_VER)
  16. # pragma once
  17. #endif
  18. #include "config_begin.hpp"
  19. #include <boost/container/detail/workaround.hpp>
  20. #include <boost/container/detail/type_traits.hpp>
  21. #include <iterator>
  22. namespace boost {
  23. namespace container {
  24. template <class PseudoReference>
  25. struct operator_arrow_proxy
  26. {
  27. operator_arrow_proxy(const PseudoReference &px)
  28. : m_value(px)
  29. {}
  30. PseudoReference* operator->() const { return &m_value; }
  31. // This function is needed for MWCW and BCC, which won't call operator->
  32. // again automatically per 13.3.1.2 para 8
  33. // operator T*() const { return &m_value; }
  34. mutable PseudoReference m_value;
  35. };
  36. template <class T>
  37. struct operator_arrow_proxy<T&>
  38. {
  39. operator_arrow_proxy(T &px)
  40. : m_value(px)
  41. {}
  42. T* operator->() const { return const_cast<T*>(&m_value); }
  43. // This function is needed for MWCW and BCC, which won't call operator->
  44. // again automatically per 13.3.1.2 para 8
  45. // operator T*() const { return &m_value; }
  46. T &m_value;
  47. };
  48. template <class Iterator, class UnaryFunction>
  49. class transform_iterator
  50. : public UnaryFunction
  51. , public std::iterator
  52. < typename Iterator::iterator_category
  53. , typename container_detail::remove_reference<typename UnaryFunction::result_type>::type
  54. , typename Iterator::difference_type
  55. , operator_arrow_proxy<typename UnaryFunction::result_type>
  56. , typename UnaryFunction::result_type>
  57. {
  58. public:
  59. explicit transform_iterator(const Iterator &it, const UnaryFunction &f = UnaryFunction())
  60. : UnaryFunction(f), m_it(it)
  61. {}
  62. explicit transform_iterator()
  63. : UnaryFunction(), m_it()
  64. {}
  65. //Constructors
  66. transform_iterator& operator++()
  67. { increment(); return *this; }
  68. transform_iterator operator++(int)
  69. {
  70. transform_iterator result (*this);
  71. increment();
  72. return result;
  73. }
  74. friend bool operator== (const transform_iterator& i, const transform_iterator& i2)
  75. { return i.equal(i2); }
  76. friend bool operator!= (const transform_iterator& i, const transform_iterator& i2)
  77. { return !(i == i2); }
  78. /*
  79. friend bool operator> (const transform_iterator& i, const transform_iterator& i2)
  80. { return i2 < i; }
  81. friend bool operator<= (const transform_iterator& i, const transform_iterator& i2)
  82. { return !(i > i2); }
  83. friend bool operator>= (const transform_iterator& i, const transform_iterator& i2)
  84. { return !(i < i2); }
  85. */
  86. friend typename Iterator::difference_type operator- (const transform_iterator& i, const transform_iterator& i2)
  87. { return i2.distance_to(i); }
  88. //Arithmetic
  89. transform_iterator& operator+=(typename Iterator::difference_type off)
  90. { this->advance(off); return *this; }
  91. transform_iterator operator+(typename Iterator::difference_type off) const
  92. {
  93. transform_iterator other(*this);
  94. other.advance(off);
  95. return other;
  96. }
  97. friend transform_iterator operator+(typename Iterator::difference_type off, const transform_iterator& right)
  98. { return right + off; }
  99. transform_iterator& operator-=(typename Iterator::difference_type off)
  100. { this->advance(-off); return *this; }
  101. transform_iterator operator-(typename Iterator::difference_type off) const
  102. { return *this + (-off); }
  103. typename UnaryFunction::result_type operator*() const
  104. { return dereference(); }
  105. operator_arrow_proxy<typename UnaryFunction::result_type>
  106. operator->() const
  107. { return operator_arrow_proxy<typename UnaryFunction::result_type>(dereference()); }
  108. Iterator & base()
  109. { return m_it; }
  110. const Iterator & base() const
  111. { return m_it; }
  112. private:
  113. Iterator m_it;
  114. void increment()
  115. { ++m_it; }
  116. void decrement()
  117. { --m_it; }
  118. bool equal(const transform_iterator &other) const
  119. { return m_it == other.m_it; }
  120. bool less(const transform_iterator &other) const
  121. { return other.m_it < m_it; }
  122. typename UnaryFunction::result_type dereference() const
  123. { return UnaryFunction::operator()(*m_it); }
  124. void advance(typename Iterator::difference_type n)
  125. { std::advance(m_it, n); }
  126. typename Iterator::difference_type distance_to(const transform_iterator &other)const
  127. { return std::distance(other.m_it, m_it); }
  128. };
  129. template <class Iterator, class UnaryFunc>
  130. transform_iterator<Iterator, UnaryFunc>
  131. make_transform_iterator(Iterator it, UnaryFunc fun)
  132. {
  133. return transform_iterator<Iterator, UnaryFunc>(it, fun);
  134. }
  135. } //namespace container {
  136. } //namespace boost {
  137. #include <boost/container/detail/config_end.hpp>
  138. #endif //#ifndef BOOST_CONTAINER_DETAIL_TRANSFORM_ITERATORS_HPP