iterator.mh

来自「开放源码的编译器open watcom 1.6.0版的源代码」· MH 代码 · 共 369 行

///////////////////////////////////////////////////////////////////////////
// FILE: iterator (Iterator utilities)
//
:keep CPP_HDR
:include crwatcnt.sp
//
// Description: This header is part of the C++ standard library. It
//              defines a number of helper templates that are useful
//              when creating or manipulating iterators.
///////////////////////////////////////////////////////////////////////////
#ifndef _ITERATOR_INCLUDED
#define _ITERATOR_INCLUDED

:include readonly.sp

#ifndef __cplusplus
#error The header iterator requires C++
#endif

#ifndef _CSTDDEF_INCLUDED
  #include <cstddef>
#endif

namespace std {

  struct input_iterator_tag  { };
  struct output_iterator_tag { };
  struct forward_iterator_tag       : public input_iterator_tag         { };
  struct bidirectional_iterator_tag : public forward_iterator_tag       { };
  struct random_access_iterator_tag : public bidirectional_iterator_tag { };

  // iterator_traits
  // ***************

  template< class Iterator >
  struct iterator_traits {
    typedef typename Iterator::difference_type   difference_type;
    typedef typename Iterator::value_type        value_type;
    typedef typename Iterator::pointer           pointer;
    typedef typename Iterator::reference         reference;
    typedef typename Iterator::iterator_catagory iterator_catagory;
  };

  template< class Type >
  struct iterator_traits< Type * > {
    typedef ptrdiff_t                  difference_type;
    typedef Type                       value_type;
    typedef Type                      *pointer;
    typedef Type                      &reference;
    typedef random_access_iterator_tag iterator_catagory;
  };

  template< class Type >
  struct iterator_traits< const Type * > {
    typedef ptrdiff_t                  difference_type;
    typedef const Type                 value_type;
    typedef const Type                *pointer;
    typedef const Type                &reference;
    typedef random_access_iterator_tag iterator_catagory;
  };

  // iterator
  // ********

  template< class Catagory,
            class Type,
            class Distance = ptrdiff_t,
            class Pointer = Type*,
            class Reference = Type& >
  struct iterator {
    typedef Type      value_type;
    typedef Distance  difference_type;
    typedef Pointer   pointer;
    typedef Reference reference;
    typedef Catagory  iterator_catagory;
  };

  // advance( Iterator &, Distance )
  // *******************************

  template< class InputIterator, class Distance >
  void advance( InputIterator &it, Distance n, input_iterator_tag )
  {
    for( Distance i = 0; i < n; ++i ) ++it;
  }

  template< class OutputIterator, class Distance >
  void advance( OutputIterator &it, Distance n, output_iterator_tag )
  {
    for( Distance i = 0; i < n; ++i ) ++it;
  }

  template< class Forward, class Distance >
  void advance( Forward &it, Distance n, forward_iterator_tag )
  {
    for( Distance i = 0; i < n; ++i ) ++it;
  }

  template< class Bidirectional, class Distance >
  void advance( Bidirectional &it, Distance n, bidirectional_iterator_tag )
  {
    if( n >= 0 ) {
      for( Distance i = 0; i < n; ++i ) ++it;
    }
    else {
      for( Distance i = 0; i > n; --i ) --it;
    }
  }

  template< class RandomAccess, class Distance >
  inline
  void advance( RandomAccess &it, Distance n, random_access_iterator_tag )
  {
    it = it + n;
  }

  template< class InputIterator, class Distance >
  inline
  void advance( InputIterator &it, Distance n )
  {
    advance(
      it, n, typename iterator_traits< InputIterator >::iterator_catagory( )
    );
  }

:: Commented out due to compiler bug.
#ifdef _NEVER
  // distance( Iterator, Iterator )
  // ******************************

  template< class InputIterator >
  typename iterator_traits< InputIterator >::difference_type
    _distance( InputIterator first, InputIterator last )
  {
    typename iterator_traits< InputIterator >::difference_type count(0);
    while( first != last ) {
      ++count;
      ++first;
    }
    return( count );
  }

  template< class InputIterator >
  inline
  typename iterator_traits< InputIterator >::difference_type
    distance( InputIterator first, InputIterator last, input_iterator_tag )
  {
    return( _distance( first, last ) );
  }

  template< class OutputIterator >
  inline
  typename iterator_traits< OutputIterator >::difference_type
    distance( OutputIterator first, OutputIterator last, output_iterator_tag )
  {
    return( _distance( first, last ) );
  }

  template< class Forward >
  inline
  typename iterator_traits< Forward >::difference_type
    distance( Forward first, Forward last, forward_iterator_tag )
  {
    return( _distance( first, last ) );
  }

  template< class Bidirectional >
  inline
  typename iterator_traits< Bidirectional >::difference_type
    distance( Bidirectional first, Bidirectional last, bidirectional_iterator_tag )
  {
    return( _distance( first, last ) );
  }

  template< class RandomAccess >
  inline
  typename iterator_traits< RandomAccess >::difference_type
    distance( RandomAccess first, RandomAccess last, random_access_iterator_tag )
  {
    return( last - first );
  }

  template< class InputIterator >
  inline
  typename iterator_traits< InputIterator >::difference_type
    distance( InputIterator first, InputIterator last )
  {
    return( distance(
      first, last, iterator_traits< InputIterator >::iterator_catagory( )
    ) );
  }
#endif

  // reverse_iterator
  // ****************

  template< class Iterator >
:: Deriving from iterator doesn't seem to work. Probable compiler bug.
  class reverse_iterator /* : public
    iterator<typename iterator_traits< Iterator >::iterator_category,
             typename iterator_traits< Iterator >::value_type,
             typename iterator_traits< Iterator >::difference_type,
             typename iterator_traits< Iterator >::pointer,
             typename iterator_traits< Iterator >::reference > */ {
  protected:
    Iterator current;

  public:
    typedef Iterator iterator_type;
:: The compiler seems bothered by iterator_category.
//    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 >::reference reference;
    typedef typename iterator_traits< Iterator >::pointer pointer;

    reverse_iterator( );
    explicit reverse_iterator( Iterator it ) : current( it )
      { }

    Iterator base( ) const
      { return( current ); }

    reference operator*( ) const
      { Iterator temp(current); --temp; return( *temp ); }

    // pointer operator->( ) const;
    //   { Iterator temp(current); --temp; return( &*temp ); }

    reverse_iterator &operator++( )
      { --current; return( *this ); }

    reverse_iterator  operator++( int )
      { reverse_iterator temp(current); --current; return( temp ); }

    reverse_iterator &operator--( )
      { ++current; return( *this ); }

    reverse_iterator  operator--( int )
      { reverse_iterator temp(current); ++current; return( temp ); }

    // reverse_iterator  operator+ ( difference_type n ) const;
    // reverse_iterator &operator+=( difference_type n );
    // reverse_iterator  operator- ( difference_type n );
    // reverse_iterator &operator-=( difference_type n );
    // reference operator[]( difference_type n ) const;
  };

  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( x.base( ) != y.base( ) );
  }

  // back_insert_iterator
  // ********************

  template< class Container >
  class back_insert_iterator :
    public iterator< output_iterator_tag, void, void, void, void > {
  protected:
    Container *container;

  public:
    typedef Container container_type;

    explicit back_insert_iterator( Container &c ) : container( &c )
      { }

    back_insert_iterator &operator=( typename Container::const_reference value )
      { container->push_back( value ); return( *this ); }

    back_insert_iterator &operator*( )
      { return( *this ); }

    back_insert_iterator &operator++( )
      { return( *this ); }

    back_insert_iterator  operator++( int )
      { return( *this ); }
  };

  template< class Container >
  back_insert_iterator< Container > back_inserter( Container &c )
    { return( back_insert_iterator< Container >( c ) ); }

  // front_insert_iterator
  // *********************

  template< class Container >
  class front_insert_iterator :
    public iterator< output_iterator_tag, void, void, void, void > {
  protected:
    Container *container;

  public:
    typedef Container container_type;

    explicit front_insert_iterator( Container &c ) : container( &c )
      { }

    front_insert_iterator &operator=( typename Container::const_reference value )
      { container->push_front( value ); return( *this ); }

    front_insert_iterator &operator*( )
      { return( *this ); }

    front_insert_iterator &operator++( )
      { return( *this ); }

    front_insert_iterator  operator++( int )
      { return( *this ); }
  };

  template< class Container >
  front_insert_iterator< Container > front_inserter( Container &c )
    { return( front_insert_iterator< Container >( c ) ); }

  // insert_iterator
  // ***************

  template< class Container >
  class insert_iterator :
    public iterator< output_iterator_tag, void, void, void, void > {
  protected:
    Container *container;
    typename Container::iterator iter;

  public:
    typedef Container container_type;

    insert_iterator( Container &c, typename Container::iterator it )
      : container( &c ), iter( it )
      { }

    insert_iterator &operator=( typename Container::const_reference value )
      { iter = container->insert( iter, value ); ++iter; return( *this ); }

    insert_iterator &operator*( )
      { return( *this ); }

    insert_iterator &operator++( )
      { return( *this ); }

    insert_iterator  operator++( int )
      { return( *this ); }
  };

  template< class Container, class Inserter >
  insert_iterator< Container > inserter( Container &c, Inserter it )
    { return( insert_iterator< Container >
        ( c, typename Container::iterator( it ) ) ); }

} // namespace std

#endif