stl_iterator.h

著名的SGI的STL lib源码.(C++范型类编成,没有合适的分类,但是放到数据结构类别中也绝对适合)

#ifndef __STL_LIMITED_DEFAULT_TEMPLATES
template <class BidirectionalIterator, class T, class Reference = T&, 
          class Distance = ptrdiff_t> 
#else
template <class BidirectionalIterator, class T, class Reference, 
          class Distance> 
#endif
class reverse_bidirectional_iterator {
  typedef reverse_bidirectional_iterator<BidirectionalIterator, T, Reference,
                                         Distance> self;
protected:
  BidirectionalIterator current;
public:
  typedef bidirectional_iterator_tag iterator_category;
  typedef T                          value_type;
  typedef Distance                   difference_type;
  typedef T*                         pointer;
  typedef Reference                  reference;

  reverse_bidirectional_iterator() {}
  explicit reverse_bidirectional_iterator(BidirectionalIterator x)
    : current(x) {}
  BidirectionalIterator base() const { return current; }
  Reference operator*() const {
    BidirectionalIterator tmp = current;
    return *--tmp;
  }
#ifndef __SGI_STL_NO_ARROW_OPERATOR
  pointer operator->() const { return &(operator*()); }
#endif /* __SGI_STL_NO_ARROW_OPERATOR */
  self& operator++() {
    --current;
    return *this;
  }
  self operator++(int) {
    self tmp = *this;
    --current;
    return tmp;
  }
  self& operator--() {
    ++current;
    return *this;
  }
  self operator--(int) {
    self tmp = *this;
    ++current;
    return tmp;
  }
};

#ifndef __STL_CLASS_PARTIAL_SPECIALIZATION

template <class BidirectionalIterator, class T, class Reference, 
          class Distance>
inline bidirectional_iterator_tag
iterator_category(const reverse_bidirectional_iterator<BidirectionalIterator,
                                                       T,
                                                       Reference, Distance>&) {
  return bidirectional_iterator_tag();
}

template <class BidirectionalIterator, class T, class Reference, 
          class Distance>
inline T*
value_type(const reverse_bidirectional_iterator<BidirectionalIterator, T,
                                               Reference, Distance>&) {
  return (T*) 0;
}

template <class BidirectionalIterator, class T, class Reference, 
          class Distance>
inline Distance*
distance_type(const reverse_bidirectional_iterator<BidirectionalIterator, T,
                                                  Reference, Distance>&) {
  return (Distance*) 0;
}

#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

template <class BidirectionalIterator, class T, class Reference,
          class Distance>
inline bool operator==(
    const reverse_bidirectional_iterator<BidirectionalIterator, T, Reference,
                                         Distance>& x, 
    const reverse_bidirectional_iterator<BidirectionalIterator, T, Reference,
                                         Distance>& y) {
  return x.base() == y.base();
}

#ifdef __STL_CLASS_PARTIAL_SPECIALIZATION

// This is the new version of reverse_iterator, as defined in the
//  draft C++ standard.  It relies on the iterator_traits template,
//  which in turn relies on partial specialization.  The class
//  reverse_bidirectional_iterator is no longer part of the draft
//  standard, but it is retained for backward compatibility.

template <class Iterator>
class reverse_iterator 
{
protected:
  Iterator current;
public:
  typedef typename iterator_traits<Iterator>::iterator_category
          iterator_category;
  typedef typename iterator_traits<Iterator>::value_type
          value_type;
  typedef typename iterator_traits<Iterator>::difference_type
          difference_type;
  typedef typename iterator_traits<Iterator>::pointer
          pointer;
  typedef typename iterator_traits<Iterator>::reference
          reference;

  typedef Iterator iterator_type;
  typedef reverse_iterator<Iterator> self;

public:
  reverse_iterator() {}
  explicit reverse_iterator(iterator_type x) : current(x) {}

  reverse_iterator(const self& x) : current(x.current) {}
#ifdef __STL_MEMBER_TEMPLATES
  template <class Iter>
  reverse_iterator(const reverse_iterator<Iter>& x) : current(x.current) {}
#endif /* __STL_MEMBER_TEMPLATES */
    
  iterator_type base() const { return current; }
  reference operator*() const {
    Iterator tmp = current;
    return *--tmp;
  }
#ifndef __SGI_STL_NO_ARROW_OPERATOR
  pointer operator->() const { return &(operator*()); }
#endif /* __SGI_STL_NO_ARROW_OPERATOR */

  self& operator++() {
    --current;
    return *this;
  }
  self operator++(int) {
    self tmp = *this;
    --current;
    return tmp;
  }
  self& operator--() {
    ++current;
    return *this;
  }
  self operator--(int) {
    self tmp = *this;
    ++current;
    return tmp;
  }

  self operator+(difference_type n) const {
    return self(current - n);
  }
  self& operator+=(difference_type n) {
    current -= n;
    return *this;
  }
  self operator-(difference_type n) const {
    return self(current + n);
  }
  self& operator-=(difference_type n) {
    current += n;
    return *this;
  }
  reference operator[](difference_type n) const { return *(*this + n); }  
}; 
 
template <class Iterator>
inline bool operator==(const reverse_iterator<Iterator>& x, 
                       const reverse_iterator<Iterator>& y) {
  return x.base() == y.base();
}

template <class Iterator>
inline bool operator<(const reverse_iterator<Iterator>& x, 
                      const reverse_iterator<Iterator>& y) {
  return y.base() < x.base();
}

template <class Iterator>
inline typename reverse_iterator<Iterator>::difference_type
operator-(const reverse_iterator<Iterator>& x, 
          const reverse_iterator<Iterator>& y) {
  return y.base() - x.base();
}

template <class Iterator>
inline reverse_iterator<Iterator> 
operator+(reverse_iterator<Iterator>::difference_type n,
          const reverse_iterator<Iterator>& x) {
  return reverse_iterator<Iterator>(x.base() - n);
}

#else /* __STL_CLASS_PARTIAL_SPECIALIZATION */

// This is the old version of reverse_iterator, as found in the original
//  HP STL.  It does not use partial specialization.

#ifndef __STL_LIMITED_DEFAULT_TEMPLATES
template <class RandomAccessIterator, class T, class Reference = T&,
          class Distance = ptrdiff_t> 
#else
template <class RandomAccessIterator, class T, class Reference,
          class Distance> 
#endif
class reverse_iterator {
  typedef reverse_iterator<RandomAccessIterator, T, Reference, Distance>
        self;
protected:
  RandomAccessIterator current;
public:
  typedef random_access_iterator_tag iterator_category;
  typedef T                          value_type;
  typedef Distance                   difference_type;
  typedef T*                         pointer;
  typedef Reference                  reference;

  reverse_iterator() {}
  explicit reverse_iterator(RandomAccessIterator x) : current(x) {}
  RandomAccessIterator base() const { return current; }
  Reference operator*() const { return *(current - 1); }
#ifndef __SGI_STL_NO_ARROW_OPERATOR
  pointer operator->() const { return &(operator*()); }
#endif /* __SGI_STL_NO_ARROW_OPERATOR */
  self& operator++() {
    --current;
    return *this;
  }
  self operator++(int) {
    self tmp = *this;
    --current;
    return tmp;
  }
  self& operator--() {
    ++current;
    return *this;
  }
  self operator--(int) {
    self tmp = *this;
    ++current;
    return tmp;
  }
  self operator+(Distance n) const {
    return self(current - n);
  }
  self& operator+=(Distance n) {
    current -= n;
    return *this;
  }
  self operator-(Distance n) const {
    return self(current + n);
  }
  self& operator-=(Distance n) {
    current += n;
    return *this;
  }
  Reference operator[](Distance n) const { return *(*this + n); }
};

template <class RandomAccessIterator, class T, class Reference, class Distance>
inline random_access_iterator_tag
iterator_category(const reverse_iterator<RandomAccessIterator, T,
                                         Reference, Distance>&) {
  return random_access_iterator_tag();
}

template <class RandomAccessIterator, class T, class Reference, class Distance>
inline T* value_type(const reverse_iterator<RandomAccessIterator, T,
                                            Reference, Distance>&) {
  return (T*) 0;
}

template <class RandomAccessIterator, class T, class Reference, class Distance>
inline Distance* distance_type(const reverse_iterator<RandomAccessIterator, T,
                                                      Reference, Distance>&) {
  return (Distance*) 0;
}


template <class RandomAccessIterator, class T, class Reference, class Distance>
inline bool operator==(const reverse_iterator<RandomAccessIterator, T,
                                              Reference, Distance>& x, 
                       const reverse_iterator<RandomAccessIterator, T,
                                              Reference, Distance>& y) {
  return x.base() == y.base();
}

template <class RandomAccessIterator, class T, class Reference, class Distance>
inline bool operator<(const reverse_iterator<RandomAccessIterator, T,
                                             Reference, Distance>& x, 
                      const reverse_iterator<RandomAccessIterator, T,
                                             Reference, Distance>& y) {
  return y.base() < x.base();
}

template <class RandomAccessIterator, class T, class Reference, class Distance>
inline Distance operator-(const reverse_iterator<RandomAccessIterator, T,
                                                 Reference, Distance>& x, 
                          const reverse_iterator<RandomAccessIterator, T,
                                                 Reference, Distance>& y) {
  return y.base() - x.base();
}

template <class RandomAccessIter, class T, class Ref, class Dist>
inline reverse_iterator<RandomAccessIter, T, Ref, Dist> 
operator+(Dist n, const reverse_iterator<RandomAccessIter, T, Ref, Dist>& x) {
  return reverse_iterator<RandomAccessIter, T, Ref, Dist>(x.base() - n);
}

#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

template <class T, class Distance = ptrdiff_t> 
class istream_iterator {
  friend bool
  operator== __STL_NULL_TMPL_ARGS (const istream_iterator<T, Distance>& x,
                                   const istream_iterator<T, Distance>& y);
protected:
  istream* stream;
  T value;
  bool end_marker;
  void read() {
    end_marker = (*stream) ? true : false;
    if (end_marker) *stream >> value;
    end_marker = (*stream) ? true : false;
  }
public:
  typedef input_iterator_tag iterator_category;
  typedef T                  value_type;
  typedef Distance           difference_type;
  typedef const T*           pointer;
  typedef const T&           reference;

  istream_iterator() : stream(&cin), end_marker(false) {}
  istream_iterator(istream& s) : stream(&s) { read(); }
  reference operator*() const { return value; }
#ifndef __SGI_STL_NO_ARROW_OPERATOR
  pointer operator->() const { return &(operator*()); }
#endif /* __SGI_STL_NO_ARROW_OPERATOR */
  istream_iterator<T, Distance>& operator++() { 
    read(); 
    return *this;
  }
  istream_iterator<T, Distance> operator++(int)  {
    istream_iterator<T, Distance> tmp = *this;
    read();
    return tmp;
  }
};

#ifndef __STL_CLASS_PARTIAL_SPECIALIZATION

template <class T, class Distance>
inline input_iterator_tag 
iterator_category(const istream_iterator<T, Distance>&) {
  return input_iterator_tag();
}

template <class T, class Distance>
inline T* value_type(const istream_iterator<T, Distance>&) { return (T*) 0; }

template <class T, class Distance>
inline Distance* distance_type(const istream_iterator<T, Distance>&) {
  return (Distance*) 0;
}

#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

template <class T, class Distance>
inline bool operator==(const istream_iterator<T, Distance>& x,
                       const istream_iterator<T, Distance>& y) {
  return x.stream == y.stream && x.end_marker == y.end_marker ||
         x.end_marker == false && y.end_marker == false;
}

template <class T>
class ostream_iterator {
protected:
  ostream* stream;
  const char* string;
public:
  typedef output_iterator_tag iterator_category;
  typedef void                value_type;
  typedef void                difference_type;
  typedef void                pointer;
  typedef void                reference;

  ostream_iterator(ostream& s) : stream(&s), string(0) {}
  ostream_iterator(ostream& s, const char* c) : stream(&s), string(c)  {}
  ostream_iterator<T>& operator=(const T& value) { 
    *stream << value;
    if (string) *stream << string;
    return *this;
  }
  ostream_iterator<T>& operator*() { return *this; }
  ostream_iterator<T>& operator++() { return *this; } 
  ostream_iterator<T>& operator++(int) { return *this; } 
};

#ifndef __STL_CLASS_PARTIAL_SPECIALIZATION

template <class T>
inline output_iterator_tag 
iterator_category(const ostream_iterator<T>&) {
  return output_iterator_tag();
}

#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

__STL_END_NAMESPACE

#endif /* __SGI_STL_INTERNAL_ITERATOR_H */

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// mode:C++
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