JBidirectionalIterator.hh

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#ifndef __JLANG__JBIDIRECTIONALITERATOR__
#define __JLANG__JBIDIRECTIONALITERATOR__
 
#include "JLang/JForwardIterator.hh"
 
/**
 * \author mdejong
 */
 
namespace JLANG {}
namespace JPP { using namespace JLANG; }
 
namespace JLANG {
 
  /**
   * Template interface for method bool decrement().
   * This interface implements the pre-fix and post-fix operators --.
   */
  template<class T> 
  class JBidirectionalIterator :
    public JForwardIterator<T>
  {
  public:
    /**
     * Virtual destructor.
     */
    virtual ~JBidirectionalIterator()
    {}
 
 
    /**
     * Decrement iterator.
     *
     * \return                 this iterator
     */
    T& operator--()
    {
      this->decrement();
 
      return static_cast<T&>(*this);
    }
    
 
    /**
     * Decrement iterator.
     *
     * \return                 decrement iterator
     */
    T operator--(int)
    {
      const T tmp(static_cast<const T&>(*this));
 
      this->decrement();
 
      return tmp;
    }
 
 
    /**
     * Regress iterator.
     *
     * \param  offset          offset
     * \return                 iterator
     */
    T& operator-=(const size_t offset)
    {
      this->decrement(offset);
 
      return static_cast<T&>(*this);
    }
 
 
    /**
     * Regress operator.
     *
     * \param  object          iterator
     * \param  offset          offset
     * \return                 iterator
     */
    friend inline T operator-(const T& object, const size_t offset)
    {
      T tmp(object);
 
      tmp.decrement(offset);
 
      return tmp;
    }
 
 
    /**
     * Decrement iterator.
     *
     * \return                 true if decremented; else false
     */
    virtual bool decrement() = 0;
 
 
    /**
     * Decrement iterator.
     *
     * \param  offset          offset
     * \return                 true if decremented; else false
     */
    virtual bool decrement(const size_t offset)
    {
      size_t i = 0;
 
      while (i != offset && this->decrement()) {
        ++i;
      }
 
      return i == offset;
    }
  };
}
 
#endif