value.h.svn-base

这是基于jsoncpp项目写扩展功能

      BucketIndex bucketsSize_;
      BucketIndex itemCount_;
   };

   /** \brief A simplified deque implementation used internally by Value.
   * \internal
   * It is based on a list of fixed "page", each page contains a fixed number of items.
   * Instead of using a linked-list, a array of pointer is used for fast item look-up.
   * Look-up for an element is as follow:
   * - compute page index: pageIndex = itemIndex / itemsPerPage
   * - look-up item in page: pages_[pageIndex][itemIndex % itemsPerPage]
   *
   * Insertion is amortized constant time (only the array containing the index of pointers
   * need to be reallocated when items are appended).
   */
   class JSON_API ValueInternalArray
   {
      friend class Value;
      friend class ValueIteratorBase;
   public:
      enum { itemsPerPage = 8 };    // should be a power of 2 for fast divide and modulo.
      typedef Value::ArrayIndex ArrayIndex;
      typedef unsigned int PageIndex;

# ifndef JSONCPP_DOC_EXCLUDE_IMPLEMENTATION
      struct IteratorState // Must be a POD
      {
         ValueInternalArray *array_;
         Value **currentPageIndex_;
         unsigned int currentItemIndex_;
      };
# endif // ifndef JSONCPP_DOC_EXCLUDE_IMPLEMENTATION

      ValueInternalArray();
      ValueInternalArray( const ValueInternalArray &other );
      ValueInternalArray &operator =( const ValueInternalArray &other );
      ~ValueInternalArray();
      void swap( ValueInternalArray &other );

      void clear();
      void resize( ArrayIndex newSize );

      Value &resolveReference( ArrayIndex index );

      Value *find( ArrayIndex index ) const;

      ArrayIndex size() const;

      int compare( const ValueInternalArray &other ) const;

   private:
      static bool equals( const IteratorState &x, const IteratorState &other );
      static void increment( IteratorState &iterator );
      static void decrement( IteratorState &iterator );
      static Value &dereference( const IteratorState &iterator );
      static Value &unsafeDereference( const IteratorState &iterator );
      static int distance( const IteratorState &x, const IteratorState &y );
      static ArrayIndex indexOf( const IteratorState &iterator );
      void makeBeginIterator( IteratorState &it ) const;
      void makeEndIterator( IteratorState &it ) const;
      void makeIterator( IteratorState &it, ArrayIndex index ) const;

      void makeIndexValid( ArrayIndex index );

      Value **pages_;
      ArrayIndex size_;
      PageIndex pageCount_;
   };

   /** \brief Allocator to customize Value internal array.
    * Below is an example of a simple implementation (actual implementation use
    * memory pool).
      \code
class DefaultValueArrayAllocator : public ValueArrayAllocator
{
public: // overridden from ValueArrayAllocator
   virtual ~DefaultValueArrayAllocator()
   {
   }

   virtual ValueInternalArray *newArray()
   {
      return new ValueInternalArray();
   }

   virtual ValueInternalArray *newArrayCopy( const ValueInternalArray &other )
   {
      return new ValueInternalArray( other );
   }

   virtual void destruct( ValueInternalArray *array )
   {
      delete array;
   }

   virtual void reallocateArrayPageIndex( Value **&indexes, 
                                          ValueInternalArray::PageIndex &indexCount,
                                          ValueInternalArray::PageIndex minNewIndexCount )
   {
      ValueInternalArray::PageIndex newIndexCount = (indexCount*3)/2 + 1;
      if ( minNewIndexCount > newIndexCount )
         newIndexCount = minNewIndexCount;
      void *newIndexes = realloc( indexes, sizeof(Value*) * newIndexCount );
      if ( !newIndexes )
         throw std::bad_alloc();
      indexCount = newIndexCount;
      indexes = static_cast<Value **>( newIndexes );
   }
   virtual void releaseArrayPageIndex( Value **indexes, 
                                       ValueInternalArray::PageIndex indexCount )
   {
      if ( indexes )
         free( indexes );
   }

   virtual Value *allocateArrayPage()
   {
      return static_cast<Value *>( malloc( sizeof(Value) * ValueInternalArray::itemsPerPage ) );
   }

   virtual void releaseArrayPage( Value *value )
   {
      if ( value )
         free( value );
   }
};
      \endcode
    */ 
   class JSON_API ValueArrayAllocator
   {
   public:
      virtual ~ValueArrayAllocator();
      virtual ValueInternalArray *newArray() = 0;
      virtual ValueInternalArray *newArrayCopy( const ValueInternalArray &other ) = 0;
      virtual void destructArray( ValueInternalArray *array ) = 0;
      /** \brief Reallocate array page index.
       * Reallocates an array of pointer on each page.
       * \param indexes [input] pointer on the current index. May be \c NULL.
       *                [output] pointer on the new index of at least 
       *                         \a minNewIndexCount pages. 
       * \param indexCount [input] current number of pages in the index.
       *                   [output] number of page the reallocated index can handle.
       *                            \b MUST be >= \a minNewIndexCount.
       * \param minNewIndexCount Minimum number of page the new index must be able to
       *                         handle.
       */
      virtual void reallocateArrayPageIndex( Value **&indexes, 
                                             ValueInternalArray::PageIndex &indexCount,
                                             ValueInternalArray::PageIndex minNewIndexCount ) = 0;
      virtual void releaseArrayPageIndex( Value **indexes, 
                                          ValueInternalArray::PageIndex indexCount ) = 0;
      virtual Value *allocateArrayPage() = 0;
      virtual void releaseArrayPage( Value *value ) = 0;
   };
#endif // #ifdef JSON_VALUE_USE_INTERNAL_MAP


   /** \brief Experimental and untested: base class for Value iterators.
    *
    */
   class ValueIteratorBase
   {
   public:
      typedef unsigned int size_t;
      typedef int difference_type;
      typedef ValueIteratorBase SelfType;

      ValueIteratorBase();
#ifndef JSON_VALUE_USE_INTERNAL_MAP
      explicit ValueIteratorBase( const Value::ObjectValues::iterator &current );
#else
      ValueIteratorBase( const ValueInternalArray::IteratorState &state );
      ValueIteratorBase( const ValueInternalMap::IteratorState &state );
#endif

      bool operator ==( const SelfType &other ) const
      {
         return isEqual( other );
      }

      bool operator !=( const SelfType &other ) const
      {
         return !isEqual( other );
      }

      difference_type operator -( const SelfType &other ) const
      {
         return computeDistance( other );
      }

      /// Return either the index or the member name of the referenced value as a Value.
      Value key() const;

      /// Return the index of the referenced Value. -1 if it is not an arrayValue.
      Value::UInt index() const;

      /// Return the member name of the referenced Value. "" if it is not an objectValue.
      const char *memberName() const;

   protected:
      Value &deref() const;

      void increment();

      void decrement();

      difference_type computeDistance( const SelfType &other ) const;

      bool isEqual( const SelfType &other ) const;

      void copy( const SelfType &other );

   private:
#ifndef JSON_VALUE_USE_INTERNAL_MAP
      Value::ObjectValues::iterator current_;
#else
      union
      {
         ValueInternalArray::IteratorState array_;
         ValueInternalMap::IteratorState map_;
      } iterator_;
      bool isArray_;
#endif
   };

   /** \brief Experimental and untested: const iterator for object and array value.
    *
    */
   class ValueConstIterator : public ValueIteratorBase
   {
      friend class Value;
   public:
      typedef unsigned int size_t;
      typedef int difference_type;
      typedef const Value &reference;
      typedef const Value *pointer;
      typedef ValueConstIterator SelfType;

      ValueConstIterator();
   private:
      /*! \internal Use by Value to create an iterator.
       */
#ifndef JSON_VALUE_USE_INTERNAL_MAP
      explicit ValueConstIterator( const Value::ObjectValues::iterator &current );
#else
      ValueConstIterator( const ValueInternalArray::IteratorState &state );
      ValueConstIterator( const ValueInternalMap::IteratorState &state );
#endif
   public:
      SelfType &operator =( const ValueIteratorBase &other );

      SelfType operator++( int )
      {
         SelfType temp( *this );
         ++*this;
         return temp;
      }

      SelfType operator--( int )
      {
         SelfType temp( *this );
         --*this;
         return temp;
      }

      SelfType &operator--()
      {
         decrement();
         return *this;
      }

      SelfType &operator++()
      {
         increment();
         return *this;
      }

      reference operator *() const
      {
         return deref();
      }
   };


   /** \brief Experimental and untested: iterator for object and array value.
    */
   class ValueIterator : public ValueIteratorBase
   {
      friend class Value;
   public:
      typedef unsigned int size_t;
      typedef int difference_type;
      typedef Value &reference;
      typedef Value *pointer;
      typedef ValueIterator SelfType;

      ValueIterator();
      ValueIterator( const ValueConstIterator &other );
      ValueIterator( const ValueIterator &other );
   private:
      /*! \internal Use by Value to create an iterator.
       */
#ifndef JSON_VALUE_USE_INTERNAL_MAP
      explicit ValueIterator( const Value::ObjectValues::iterator &current );
#else
      ValueIterator( const ValueInternalArray::IteratorState &state );
      ValueIterator( const ValueInternalMap::IteratorState &state );
#endif
   public:

      SelfType &operator =( const SelfType &other );

      SelfType operator++( int )
      {
         SelfType temp( *this );
         ++*this;
         return temp;
      }

      SelfType operator--( int )
      {
         SelfType temp( *this );
         --*this;
         return temp;
      }

      SelfType &operator--()
      {
         decrement();
         return *this;
      }

      SelfType &operator++()
      {
         increment();
         return *this;
      }

      reference operator *() const
      {
         return deref();
      }
   };


} // namespace Json


#endif // CPPTL_JSON_H_INCLUDED