comparison third_party/json/value.h @ 0:add35537fdbb tip

Initial import

+// Copyright 2007-2010 Baptiste Lepilleur
+// Distributed under MIT license, or public domain if desired and
+// recognized in your jurisdiction.
+// See file LICENSE for detail or copy at http://jsoncpp.sourceforge.net/LICENSE
+
+#ifndef CPPTL_JSON_H_INCLUDED
+# define CPPTL_JSON_H_INCLUDED
+
+#if !defined(JSON_IS_AMALGAMATION)
+# include "forwards.h"
+#endif // if !defined(JSON_IS_AMALGAMATION)
+# 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 ValueIterator iterator;
+      typedef ValueConstIterator const_iterator;
+      typedef Json::UInt UInt;
+      typedef Json::Int Int;
+# if defined(JSON_HAS_INT64)
+      typedef Json::UInt64 UInt64;
+      typedef Json::Int64 Int64;
+#endif // defined(JSON_HAS_INT64)
+      typedef Json::LargestInt LargestInt;
+      typedef Json::LargestUInt LargestUInt;
+      typedef Json::ArrayIndex ArrayIndex;
+
+      static const Value null;
+      /// Minimum signed integer value that can be stored in a Json::Value.
+      static const LargestInt minLargestInt;
+      /// Maximum signed integer value that can be stored in a Json::Value.
+      static const LargestInt maxLargestInt;
+      /// Maximum unsigned integer value that can be stored in a Json::Value.
+      static const LargestUInt maxLargestUInt;
+
+      /// Minimum signed int value that can be stored in a Json::Value.
+      static const Int minInt;
+      /// Maximum signed int value that can be stored in a Json::Value.
+      static const Int maxInt;
+      /// Maximum unsigned int value that can be stored in a Json::Value.
+      static const UInt maxUInt;
+
+# if defined(JSON_HAS_INT64)
+      /// Minimum signed 64 bits int value that can be stored in a Json::Value.
+      static const Int64 minInt64;
+      /// Maximum signed 64 bits int value that can be stored in a Json::Value.
+      static const Int64 maxInt64;
+      /// Maximum unsigned 64 bits int value that can be stored in a Json::Value.
+      static const UInt64 maxUInt64;
+#endif // defined(JSON_HAS_INT64)
+
+   private:
+#ifndef JSONCPP_DOC_EXCLUDE_IMPLEMENTATION
+# ifndef JSON_VALUE_USE_INTERNAL_MAP
+      class CZString 
+      {
+      public:
+         enum DuplicationPolicy 
+         {
+            noDuplication = 0,
+            duplicate,
+            duplicateOnCopy
+         };
+         CZString( ArrayIndex 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;
+         ArrayIndex index() const;
+         const char *c_str() const;
+         bool isStaticString() const;
+      private:
+         void swap( CZString &other );
+         const char *cstr_;
+         ArrayIndex 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:
+      /** \brief Create a default Value of the given type.
+
+        This is a very useful constructor.
+        To create an empty array, pass arrayValue.
+        To create an empty object, pass objectValue.
+        Another Value can then be set to this one by assignment.
+    This is useful since clear() and resize() will not alter types.
+
+        Examples:
+    \code
+    Json::Value null_value; // null
+    Json::Value arr_value(Json::arrayValue); // []
+    Json::Value obj_value(Json::objectValue); // {}
+    \endcode
+      */
+      Value( ValueType type = nullValue );
+      Value( Int value );
+      Value( UInt value );
+#if defined(JSON_HAS_INT64)
+      Value( Int64 value );
+      Value( UInt64 value );
+#endif // if defined(JSON_HAS_INT64)
+      Value( double value );
+      Value( const char *value );
+      Value( const char *beginValue, const char *endValue );
+      /** \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 );
+      /// Swap values.
+      /// \note Currently, comments are intentionally not swapped, for
+      /// both logic and efficiency.
+      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;
+
+      const char *asCString() const;
+      std::string asString() const;
+# ifdef JSON_USE_CPPTL
+      CppTL::ConstString asConstString() const;
+# endif
+      Int asInt() const;
+      UInt asUInt() const;
+#if defined(JSON_HAS_INT64)
+      Int64 asInt64() const;
+      UInt64 asUInt64() const;
+#endif // if defined(JSON_HAS_INT64)
+      LargestInt asLargestInt() const;
+      LargestUInt asLargestUInt() const;
+      float asFloat() const;
+      double asDouble() const;
+      bool asBool() const;
+
+      bool isNull() const;
+      bool isBool() const;
+      bool isInt() const;
+      bool isInt64() const;
+      bool isUInt() const;
+      bool isUInt64() 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
+      ArrayIndex size() const;
+
+      /// \brief Return true if empty array, empty object, or null;
+      /// otherwise, false.
+      bool empty() const;
+
+      /// Return isNull()
+      bool operator!() const;
+
+      /// Remove all object members and array elements.
+      /// \pre type() is arrayValue, objectValue, or nullValue
+      /// \post type() is unchanged
+      void clear();
+
+      /// Resize the array to size elements. 
+      /// New elements are initialized to null.
+      /// May only be called on nullValue or arrayValue.
+      /// \pre type() is arrayValue or nullValue
+      /// \post type() is arrayValue
+      void resize( ArrayIndex 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.
+      /// (You may need to say 'value[0u]' to get your compiler to distinguish
+      ///  this from the operator[] which takes a string.)
+      Value &operator[]( ArrayIndex index );
+
+      /// 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.
+      /// (You may need to say 'value[0u]' to get your compiler to distinguish
+      ///  this from the operator[] which takes a string.)
+      Value &operator[]( int index );
+
+      /// Access an array element (zero based index )
+      /// (You may need to say 'value[0u]' to get your compiler to distinguish
+      ///  this from the operator[] which takes a string.)
+      const Value &operator[]( ArrayIndex index ) const;
+
+      /// Access an array element (zero based index )
+      /// (You may need to say 'value[0u]' to get your compiler to distinguish
+      ///  this from the operator[] which takes a string.)
+      const Value &operator[]( int index ) const;
+
+      /// If the array contains at least index+1 elements, returns the element value, 
+      /// otherwise returns defaultValue.
+      Value get( ArrayIndex index, 
+                 const Value &defaultValue ) const;
+      /// Return true if index < size().
+      bool isValidIndex( ArrayIndex index ) const;
+      /// \brief 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
+      /// Return the member named key if it exist, defaultValue otherwise.
+      Value get( const char *key, 
+                 const Value &defaultValue ) const;
+      /// Return the member named key if it exist, defaultValue otherwise.
+      Value get( const std::string &key,
+                 const Value &defaultValue ) const;
+# ifdef JSON_USE_CPPTL
+      /// Return the member named key if it exist, defaultValue otherwise.
+      Value get( const CppTL::ConstString &key,
+                 const Value &defaultValue ) const;
+# endif
+      /// \brief Remove and return the named member.  
+      ///
+      /// Do nothing if it did not exist.
+      /// \return the removed Value, or null.
+      /// \pre type() is objectValue or nullValue
+      /// \post type() is unchanged
+      Value removeMember( const char* key );
+      /// Same as removeMember(const char*)
+      Value removeMember( const std::string &key );
+
+      /// Return true if the object has a member named key.
+      bool isMember( const char *key ) const;
+      /// Return true if the object has a member named key.
+      bool isMember( const std::string &key ) const;
+# ifdef JSON_USE_CPPTL
+      /// Return true if the object has a member named key.
+      bool isMember( const CppTL::ConstString &key ) const;
+# endif
+
+      /// \brief Return a list of the member names.
+      ///
+      /// If null, return an empty list.
+      /// \pre type() is objectValue or nullValue
+      /// \post if type() was nullValue, it remains nullValue
+      Members getMemberNames() const;
+
+//# ifdef JSON_USE_CPPTL
+//      EnumMemberNames enumMemberNames() const;
+//      EnumValues enumValues() const;
+//# endif
+
+      /// Comments must be //... or /* ... */
+      void setComment( const char *comment,
+                       CommentPlacement placement );
+      /// Comments must be //... or /* ... */
+      void setComment( const std::string &comment,
+                       CommentPlacement placement );
+      bool hasComment( CommentPlacement placement ) const;
+      /// Include delimiters and embedded newlines.
+      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
+      {
+         LargestInt int_;
+         LargestUInt 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( ArrayIndex index );
+      PathArgument( const char *key );
+      PathArgument( const std::string &key );
+
+   private:
+      enum Kind
+      {
+         kindNone = 0,
+         kindIndex,
+         kindKey
+      };
+      std::string key_;
+      ArrayIndex 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_;
+   };
+
+
+
+#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
+      {
+         IteratorState() 
+            : map_(0)
+            , link_(0)
+            , itemIndex_(0)
+            , bucketIndex_(0) 
+         {
+         }
+         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
+      {
+         IteratorState() 
+            : array_(0)
+            , currentPageIndex_(0)
+            , currentItemIndex_(0) 
+         {
+         }
+         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 Experimental: do not use. 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 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.
+      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_;
+      // Indicates that iterator is for a null value.
+      bool isNull_;
+#else
+      union
+      {
+         ValueInternalArray::IteratorState array_;
+         ValueInternalMap::IteratorState map_;
+      } iterator_;
+      bool isArray_;
+#endif
+   };
+
+   /** \brief 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 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