JSTDObjectIterator.hh

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#ifndef __JLANG__JSTDOBJECTITERATOR__
#define __JLANG__JSTDOBJECTITERATOR__
 
#include <iterator>
#include <algorithm>
 
#include "JLang/JObjectIterator.hh"
#include "JLang/JClass.hh"
#include "JLang/JCategory.hh"
 
 
/**
 * \author mdejong
 */
 
namespace JLANG {}
namespace JPP { using namespace JLANG; }
 
namespace JLANG {
 
  /**
   * Implementation of object iteration from STD container.
   */
  template<class T>
  struct JSTDObjectIterator :
    public JRewindableObjectIterator<typename JCategory<typename T::value_type,
                                                        JClass<typename T::reference>::is_constant>::value_type>
  {
    typedef typename JCategory<typename T::value_type,
                               JClass<typename T::reference>::is_constant>::value_type      value_type;
    typedef typename JRewindableObjectIterator<value_type>::pointer_type                    pointer_type;
 
    /**
     * Default constructor.
     */
    JSTDObjectIterator()
    {}
 
 
    /**
     * Constructor.
     *
     * \param  begin      begin of data
     * \param  end        end   of data
     */
    JSTDObjectIterator(T begin,
                       T end) :
      __begin(begin),
      __end  (end),
      __i    (begin)
    {}
 
    
    /**
     * Rewind.
     */
    virtual void rewind() override 
    {
      __i = __begin;
    }
 
 
    /**
     * Check availability of next element.
     *
     * \return            true if the iteration has more elements; else false
     */
    virtual bool hasNext() override 
    {
      return __i != __end;
    }
 
 
    /**
     * Get next element.
     *
     * \return            pointer to element
     */
    virtual const pointer_type& next() override 
    {
      if (hasNext())
        ps.reset(&(*__i++));
      else
        ps.reset(NULL);
      
      return ps;
    }
 
 
    /**
     * Skip items.
     *
     * \param  ns         number of items to skip
     * \return            number of items skipped
     */
    virtual skip_type skip(const skip_type ns) override 
    {
      using namespace std;
 
      skip_type i = min(ns, (skip_type) distance(__i, __end));
      
      advance(__i, i);
 
      return i;
    }
 
  protected:
    T __begin;
    T __end;
    T __i;
  private:
    pointer_type ps;
  };
}
 
#endif