jsoncpp/include/json/value.h

#ifndef CPPTL_JSON_H_INCLUDED
# define CPPTL_JSON_H_INCLUDED

# include "forwards.h"
# include <string>
# include <vector>

# ifndef JSON_USE_CPPTL_SMALLMAP
#  include <map>
# else
#  include <cpptl/smallmap.h>
# endif
# ifdef JSON_USE_CPPTL
#  include <cpptl/forwards.h>
# endif

/** \brief JSON (JavaScript Object Notation).
 */
namespace Json {

   /** \brief Type of the value held by a Value object.
    */
   enum ValueType
   {
      nullValue = 0, ///< 'null' value
      intValue,      ///< signed integer value
      uintValue,     ///< unsigned integer value
      realValue,     ///< double value
      stringValue,   ///< UTF-8 string value
      booleanValue,  ///< bool value
      arrayValue,    ///< array value (ordered list)
      objectValue    ///< object value (collection of name/value pairs).
   };

   enum CommentPlacement
   {
      commentBefore = 0,        ///< a comment placed on the line before a value
      commentAfterOnSameLine,   ///< a comment just after a value on the same line
      commentAfter,             ///< a comment on the line after a value (only make sense for root value)
      numberOfCommentPlacement
   };

//# ifdef JSON_USE_CPPTL
//   typedef CppTL::AnyEnumerator<const char *> EnumMemberNames;
//   typedef CppTL::AnyEnumerator<const Value &> EnumValues;
//# endif

   /** \brief Lightweight wrapper to tag static string.
    *
    * Value constructor and objectValue member assignement takes advantage of the
    * StaticString and avoid the cost of string duplication when storing the
    * string or the member name.
    *
    * Example of usage:
    * \code
    * Json::Value aValue( StaticString("some text") );
    * Json::Value object;
    * static const StaticString code("code");
    * object[code] = 1234;
    * \endcode
    */
   class JSON_API StaticString
   {
   public:
      explicit StaticString( const char *czstring )
         : str_( czstring )
      {
      }

      operator const char *() const
      {
         return str_;
      }

      const char *c_str() const
      {
         return str_;
      }

   private:
      const char *str_;
   };

   /** \brief Represents a <a HREF="http://www.json.org">JSON</a> value.
    *
    * This class is a discriminated union wrapper that can represents a:
    * - signed integer [range: Value::minInt - Value::maxInt]
    * - unsigned integer (range: 0 - Value::maxUInt)
    * - double
    * - UTF-8 string
    * - boolean
    * - 'null'
    * - an ordered list of Value
    * - collection of name/value pairs (javascript object)
    *
    * The type of the held value is represented by a #ValueType and 
    * can be obtained using type().
    *
    * values of an #objectValue or #arrayValue can be accessed using operator[]() methods. 
    * Non const methods will automatically create the a #nullValue element 
    * if it does not exist. 
    * The sequence of an #arrayValue will be automatically resize and initialized 
    * with #nullValue. resize() can be used to enlarge or truncate an #arrayValue.
    *
    * The get() methods can be used to obtanis default value in the case the required element
    * does not exist.
    *
    * It is possible to iterate over the list of a #objectValue values using 
    * the getMemberNames() method.
    */
   class JSON_API Value 
   {
      friend class ValueIteratorBase;
# ifdef JSON_VALUE_USE_INTERNAL_MAP
      friend class ValueInternalLink;
      friend class ValueInternalMap;
# endif
   public:
      typedef std::vector<std::string> Members;
      typedef int Int;
      typedef unsigned int UInt;
      typedef ValueIterator iterator;
      typedef ValueConstIterator const_iterator;
      typedef UInt ArrayIndex;

      static const Value null;
      static const Int minInt;
      static const Int maxInt;
      static const UInt maxUInt;

   private:
#ifndef JSONCPP_DOC_EXCLUDE_IMPLEMENTATION
# ifndef JSON_VALUE_USE_INTERNAL_MAP
      class CZString 
      {
      public:
         enum DuplicationPolicy 
         {
            noDuplication = 0,
            duplicate,
            duplicateOnCopy
         };
         CZString( int index );
         CZString( const char *cstr, DuplicationPolicy allocate );
         CZString( const CZString &other );
         ~CZString();
         CZString &operator =( const CZString &other );
         bool operator<( const CZString &other ) const;
         bool operator==( const CZString &other ) const;
         int index() const;
         const char *c_str() const;
         bool isStaticString() const;
      private:
         void swap( CZString &other );
         const char *cstr_;
         int index_;
      };

   public:
#  ifndef JSON_USE_CPPTL_SMALLMAP
      typedef std::map<CZString, Value> ObjectValues;
#  else
      typedef CppTL::SmallMap<CZString, Value> ObjectValues;
#  endif // ifndef JSON_USE_CPPTL_SMALLMAP
# endif // ifndef JSON_VALUE_USE_INTERNAL_MAP
#endif // ifndef JSONCPP_DOC_EXCLUDE_IMPLEMENTATION

   public:
      Value( ValueType type = nullValue );
      Value( Int value );
      Value( UInt value );
      Value( double value );
      Value( const char *value );
      /** \brief Constructs a value from a static string.
       * Like other value string constructor but do not duplicate the string for
       * internal storage. The given string must remain alive after the call to this
       * constructor.
       * Example of usage:
       * \code
       * Json::Value aValue( StaticString("some text") );
       * \endcode
       */
      Value( const StaticString &value );
      Value( const std::string &value );
# ifdef JSON_USE_CPPTL
      Value( const CppTL::ConstString &value );
# endif
      Value( bool value );
      Value( const Value &other );
      ~Value();

      Value &operator=( const Value &other );
      void swap( Value &other );

      ValueType type() const;

      bool operator <( const Value &other ) const;
      bool operator <=( const Value &other ) const;
      bool operator >=( const Value &other ) const;
      bool operator >( const Value &other ) const;

      bool operator ==( const Value &other ) const;
      bool operator !=( const Value &other ) const;

      int compare( const Value &other );

      const char *asCString() const;
      std::string asString() const;
# ifdef JSON_USE_CPPTL
      CppTL::ConstString asConstString() const;
# endif
      Int asInt() const;
      UInt asUInt() const;
      double asDouble() const;
      bool asBool() const;

      bool isBool() const;
      bool isInt() const;
      bool isUInt() const;
      bool isIntegral() const;
      bool isDouble() const;
      bool isNumeric() const;
      bool isString() const;
      bool isArray() const;
      bool isObject() const;

      bool isConvertibleTo( ValueType other ) const;

      /// Number of values in array or object
      UInt size() const;

      /// Removes all object members and array elements.
      void clear();

      /// Resize the array to size elements. 
      /// New elements are initialized to null.
      /// May only be called on nullValue or arrayValue.
      void resize( UInt size );

      /// Access an array element (zero based index ).
      /// If the array contains less than index element, then null value are inserted
      /// in the array so that its size is index+1.
      Value &operator[]( UInt index );
      /// Access an array element (zero based index )
      const Value &operator[]( UInt index ) const;
      /// If the array contains at least index+1 elements, returns the element value, 
      /// otherwise returns defaultValue.
      Value get( UInt index, 
                 const Value &defaultValue ) const;
      /// Returns true if index < size().
      bool isValidIndex( UInt index ) const;
      /// Append value to array at the end.
      /// Equivalent to jsonvalue[jsonvalue.size()] = value;
      Value &append( const Value &value );

      /// Access an object value by name, create a null member if it does not exist.
      Value &operator[]( const char *key );
      /// Access an object value by name, returns null if there is no member with that name.
      const Value &operator[]( const char *key ) const;
      /// Access an object value by name, create a null member if it does not exist.
      Value &operator[]( const std::string &key );
      /// Access an object value by name, returns null if there is no member with that name.
      const Value &operator[]( const std::string &key ) const;
      /** \brief Access an object value by name, create a null member if it does not exist.
       * If the object as no entry for that name, then the member name used to store
       * the new entry is not duplicated.
       * Example of use:
       * \code
       * Json::Value object;
       * static const StaticString code("code");
       * object[code] = 1234;
       * \endcode
       */
      Value &operator[]( const StaticString &key );
# ifdef JSON_USE_CPPTL
      /// Access an object value by name, create a null member if it does not exist.
      Value &operator[]( const CppTL::ConstString &key );
      /// Access an object value by name, returns null if there is no member with that name.
      const Value &operator[]( const CppTL::ConstString &key ) const;
# endif
      /// Returns the member named key if it exist, defaultValue otherwise.
      Value get( const char *key, 
                 const Value &defaultValue ) const;
      /// Returns the member named key if it exist, defaultValue otherwise.
      Value get( const std::string &key,
                 const Value &defaultValue ) const;
# ifdef JSON_USE_CPPTL
      /// Returns the member named key if it exist, defaultValue otherwise.
      Value get( const CppTL::ConstString &key,
                 const Value &defaultValue ) const;
# endif
      /// Returns true if the object has a member named key.
      bool isMember( const char *key ) const;
      /// Returns true if the object has a member named key.
      bool isMember( const std::string &key ) const;
# ifdef JSON_USE_CPPTL
      /// Returns true if the object has a member named key.
      bool isMember( const CppTL::ConstString &key ) const;
# endif

      // Returns a list of the member names.
      Members getMemberNames() const;

//# ifdef JSON_USE_CPPTL
//      EnumMemberNames enumMemberNames() const;
//      EnumValues enumValues() const;
//# endif

      void setComment( const char *comment,
                       CommentPlacement placement );
      void setComment( const std::string &comment,
                       CommentPlacement placement );
      bool hasComment( CommentPlacement placement ) const;
      std::string getComment( CommentPlacement placement ) const;

      std::string toStyledString() const;

      const_iterator begin() const;
      const_iterator end() const;

      iterator begin();
      iterator end();

   private:
      Value &resolveReference( const char *key, 
                               bool isStatic );

# ifdef JSON_VALUE_USE_INTERNAL_MAP
      inline bool isItemAvailable() const
      {
         return itemIsUsed_ == 0;
      }

      inline void setItemUsed( bool isUsed = true )
      {
         itemIsUsed_ = isUsed ? 1 : 0;
      }

      inline bool isMemberNameStatic() const
      {
         return memberNameIsStatic_ == 0;
      }

      inline void setMemberNameIsStatic( bool isStatic )
      {
         memberNameIsStatic_ = isStatic ? 1 : 0;
      }
# endif // # ifdef JSON_VALUE_USE_INTERNAL_MAP

   private:
      struct CommentInfo
      {
         CommentInfo();
         ~CommentInfo();

         void setComment( const char *text );

         char *comment_;
      };

      //struct MemberNamesTransform
      //{
      //   typedef const char *result_type;
      //   const char *operator()( const CZString &name ) const
      //   {
      //      return name.c_str();
      //   }
      //};

      union ValueHolder
      {
         Int int_;
         UInt uint_;
         double real_;
         bool bool_;
         char *string_;
# ifdef JSON_VALUE_USE_INTERNAL_MAP
         ValueInternalArray *array_;
         ValueInternalMap *map_;
#else
         ObjectValues *map_;
# endif
      } value_;
      ValueType type_ : 8;
      int allocated_ : 1;     // Notes: if declared as bool, bitfield is useless.
# ifdef JSON_VALUE_USE_INTERNAL_MAP
      unsigned int itemIsUsed_ : 1;      // used by the ValueInternalMap container.
      int memberNameIsStatic_ : 1;       // used by the ValueInternalMap container.
# endif
      CommentInfo *comments_;
   };


   /** \brief Experimental and untested: represents an element of the "path" to access a node.
    */
   class PathArgument
   {
   public:
      friend class Path;

      PathArgument();
      PathArgument( Value::UInt index );
      PathArgument( const char *key );
      PathArgument( const std::string &key );

   private:
      enum Kind
      {
         kindNone = 0,
         kindIndex,
         kindKey
      };
      std::string key_;
      Value::UInt index_;
      Kind kind_;
   };

   /** \brief Experimental and untested: represents a "path" to access a node.
    *
    * Syntax:
    * - "." => root node
    * - ".[n]" => elements at index 'n' of root node (an array value)
    * - ".name" => member named 'name' of root node (an object value)
    * - ".name1.name2.name3"
    * - ".[0][1][2].name1[3]"
    * - ".%" => member name is provided as parameter
    * - ".[%]" => index is provied as parameter
    */
   class Path
   {
   public:
      Path( const std::string &path,
            const PathArgument &a1 = PathArgument(),
            const PathArgument &a2 = PathArgument(),
            const PathArgument &a3 = PathArgument(),
            const PathArgument &a4 = PathArgument(),
            const PathArgument &a5 = PathArgument() );

      const Value &resolve( const Value &root ) const;
      Value resolve( const Value &root, 
                     const Value &defaultValue ) const;
      /// Creates the "path" to access the specified node and returns a reference on the node.
      Value &make( Value &root ) const;

   private:
      typedef std::vector<const PathArgument *> InArgs;
      typedef std::vector<PathArgument> Args;

      void makePath( const std::string &path,
                     const InArgs &in );
      void addPathInArg( const std::string &path, 
                         const InArgs &in, 
                         InArgs::const_iterator &itInArg, 
                         PathArgument::Kind kind );
      void invalidPath( const std::string &path, 
                        int location );

      Args args_;
   };

   /** \brief Allocator to customize member name and string value memory management done by Value.
    *
    * - makeMemberName() and releaseMemberName() are called to respectively duplicate and
    *   free an Json::objectValue member name.
    * - duplicateStringValue() and releaseStringValue() are called similarly to
    *   duplicate and free a Json::stringValue value.
    */
   class ValueAllocator
   {
   public:
      enum { unknown = -1 };

      virtual ~ValueAllocator();

      virtual char *makeMemberName( const char *memberName ) = 0;
      virtual void releaseMemberName( char *memberName ) = 0;
      virtual char *duplicateStringValue( const char *value, 
                                          unsigned int length = unknown ) = 0;
      virtual void releaseStringValue( char *value ) = 0;
   };

#ifdef JSON_VALUE_USE_INTERNAL_MAP
   /** \brief Allocator to customize Value internal map.
    * Below is an example of a simple implementation (default implementation actually
    * use memory pool for speed).
    * \code
      class DefaultValueMapAllocator : public ValueMapAllocator
      {
      public: // overridden from ValueMapAllocator
         virtual ValueInternalMap *newMap()
         {
            return new ValueInternalMap();
         }

         virtual ValueInternalMap *newMapCopy( const ValueInternalMap &other )
         {
            return new ValueInternalMap( other );
         }

         virtual void destructMap( ValueInternalMap *map )
         {
            delete map;
         }

         virtual ValueInternalLink *allocateMapBuckets( unsigned int size )
         {
            return new ValueInternalLink[size];
         }

         virtual void releaseMapBuckets( ValueInternalLink *links )
         {
            delete [] links;
         }

         virtual ValueInternalLink *allocateMapLink()
         {
            return new ValueInternalLink();
         }

         virtual void releaseMapLink( ValueInternalLink *link )
         {
            delete link;
         }
      };
    * \endcode
    */ 
   class JSON_API ValueMapAllocator
   {
   public:
      virtual ~ValueMapAllocator();
      virtual ValueInternalMap *newMap() = 0;
      virtual ValueInternalMap *newMapCopy( const ValueInternalMap &other ) = 0;
      virtual void destructMap( ValueInternalMap *map ) = 0;
      virtual ValueInternalLink *allocateMapBuckets( unsigned int size ) = 0;
      virtual void releaseMapBuckets( ValueInternalLink *links ) = 0;
      virtual ValueInternalLink *allocateMapLink() = 0;
      virtual void releaseMapLink( ValueInternalLink *link ) = 0;
   };

   /** \brief ValueInternalMap hash-map bucket chain link (for internal use only).
    * \internal previous_ & next_ allows for bidirectional traversal.
    */
   class JSON_API ValueInternalLink
   {
   public:
      enum { itemPerLink = 6 };  // sizeof(ValueInternalLink) = 128 on 32 bits architecture.
      enum InternalFlags { 
         flagAvailable = 0,
         flagUsed = 1
      };

      ValueInternalLink();

      ~ValueInternalLink();

      Value items_[itemPerLink];
      char *keys_[itemPerLink];
      ValueInternalLink *previous_;
      ValueInternalLink *next_;
   };


   /** \brief A linked page based hash-table implementation used internally by Value.
    * \internal ValueInternalMap is a tradional bucket based hash-table, with a linked
    * list in each bucket to handle collision. There is an addional twist in that
    * each node of the collision linked list is a page containing a fixed amount of
    * value. This provides a better compromise between memory usage and speed.
    * 
    * Each bucket is made up of a chained list of ValueInternalLink. The last
    * link of a given bucket can be found in the 'previous_' field of the following bucket.
    * The last link of the last bucket is stored in tailLink_ as it has no following bucket.
    * Only the last link of a bucket may contains 'available' item. The last link always
    * contains at least one element unless is it the bucket one very first link.
    */
   class JSON_API ValueInternalMap
   {
      friend class ValueIteratorBase;
      friend class Value;
   public:
      typedef unsigned int HashKey;
      typedef unsigned int BucketIndex;

# ifndef JSONCPP_DOC_EXCLUDE_IMPLEMENTATION
      struct IteratorState
      {
         ValueInternalMap *map_;
         ValueInternalLink *link_;
         BucketIndex itemIndex_;
         BucketIndex bucketIndex_;
      };
# endif // ifndef JSONCPP_DOC_EXCLUDE_IMPLEMENTATION

      ValueInternalMap();
      ValueInternalMap( const ValueInternalMap &other );
      ValueInternalMap &operator =( const ValueInternalMap &other );
      ~ValueInternalMap();

      void swap( ValueInternalMap &other );

      BucketIndex size() const;

      void clear();

      bool reserveDelta( BucketIndex growth );

      bool reserve( BucketIndex newItemCount );

      const Value *find( const char *key ) const;

      Value *find( const char *key );

      Value &resolveReference( const char *key, 
                               bool isStatic );

      void remove( const char *key );

      void doActualRemove( ValueInternalLink *link, 
                           BucketIndex index,
                           BucketIndex bucketIndex );

      ValueInternalLink *&getLastLinkInBucket( BucketIndex bucketIndex );

      Value &setNewItem( const char *key, 
                         bool isStatic, 
                         ValueInternalLink *link, 
                         BucketIndex index );

      Value &unsafeAdd( const char *key, 
                        bool isStatic, 
                        HashKey hashedKey );

      HashKey hash( const char *key ) const;

      int compare( const ValueInternalMap &other ) const;

   private:
      void makeBeginIterator( IteratorState &it ) const;
      void makeEndIterator( IteratorState &it ) const;
      static bool equals( const IteratorState &x, const IteratorState &other );
      static void increment( IteratorState &iterator );
      static void incrementBucket( IteratorState &iterator );
      static void decrement( IteratorState &iterator );
      static const char *key( const IteratorState &iterator );
      static const char *key( const IteratorState &iterator, bool &isStatic );
      static Value &value( const IteratorState &iterator );
      static int distance( const IteratorState &x, const IteratorState &y );

   private:
      ValueInternalLink *buckets_;
      ValueInternalLink *tailLink_;
      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 );
      }

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

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

      /// Returns 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