[boost] property accessor specialization for pointer

From: jsiek_at_[hidden]
Date: 1999-12-14 13:16:54

Here's a specialization for pointers that should probably
go in the property_accessor.hpp file.

(at some pointer the ptrdiff_t should be replaced with
iterator_traits<T*>::difference_type, but ptrdiff_t is more portable
for now)

#ifndef BOOST_PROPERTY_ACCESSOR_HPP
#define BOOST_PROPERTY_ACCESSOR_HPP

namespace boost {

  struct readable_property_accessor_tag {};
  struct writable_property_accessor_tag {};
  struct read_write_property_accessor_tag:
    readable_property_accessor_tag,
    writable_property_accessor_tag {};
  struct lvalue_property_accessor_tag:
    read_write_property_accessor_tag {};
  
  template <typename PA>
  struct property_traits {
    typedef typename PA::value_type value_type; 
    typedef typename PA::category   category;
  };

  // The property accessor specialization for pointers

  template <class T>
  struct property_traits<T*> {
    typedef T value_type;
    typedef lvalue_property_accessor_tag category;
  };
  template <class T>
  void set(T* pa, ptrdiff_t it, const T& val)
  { 
    pa[it] = val; 
  }
  template <class T>
  T get(T* pa, ptrdiff_t it)
  { 
    return pa[it]; 
  }
  template <class T>
  T& at(T* pa, ptrdiff_t it)
  { 
    return pa[it]; 
  }

} /* namespace boost */

#endif /* BOOST_PROPERTY_ACCESSOR_HPP */