Changeset 116

Timestamp:

Jan 5, 2011, 7:58:26 AM (13 years ago)

Author:

george

Message:

• Added: Unit UStreamHelper as replacement to TMemoryStreamEx. Helper class can extend TStream functionality without affecting base class itself.
• Modified: Class TVarIntSerializer renamed to TVarBlockSerializer as Variable Block is more precise term for serialized elements. Variable integer is special case of Variable block (block with coded variable length).
• Added: Class TVarBlockIndexed which handle access to indexed items in VarBlocks. It Use first item in block as BitArray field which determine presence of rest of items.

Location:

VarBlockSerializer

Files:

• Demo (added)
• UStreamHelper.pas (added)
• UVarBlockSerializer.pas (moved) (moved from VarBlockSerializer/UVarIntSerializer.pas ) (12 diffs)

VarBlockSerializer/UVarBlockSerializer.pas

@@ -1 +1 @@
 // 2010-03-30
 
-unit UVarIntSerializer;
+unit UVarBlockSerializer;
 
 {$mode Delphi}{$H+}
@@ -11 +11 @@
 
 uses
-  Classes, DateUtils, UMemoryStreamEx, Math, Dialogs, SysUtils, USubStream;
+  Classes, DateUtils, UStreamHelper, Math, Dialogs, SysUtils, USubStream,
+  Contnrs, SpecializedList;
 
 const
@@ -18 +19 @@
 
 type
-  { TVarIntSerializer }
-
-  TVarIntSerializer = class(TMemoryStreamEx)
+
+  { TVarBlockSerializer }
+
+  TVarBlockSerializer = class
   private
+    FStream: TStream;
+    procedure SetStream(const AValue: TStream);
     procedure TrimLeft;
     function GetUnaryLengthMask(Length: Integer): Byte;
     function DecodeUnaryLength(Data: Byte): Integer;
   public
+    OwnsStream: Boolean;
+
     // Base
     procedure WriteVarUInt(Value: QWord);
     function ReadVarUInt: QWord;
-    procedure WriteVarBlock(Stream: TStream);
-    procedure ReadVarBlock(Stream: TStream);
+    procedure WriteVarBlock(Block: TVarBlockSerializer);
+    procedure ReadVarBlock(Block: TVarBlockSerializer);
+    procedure WriteVarStream(AStream: TStream);
+    procedure ReadVarStream(AStream: TStream);
     function GetVarSize: Integer;
 
@@ -43 +51 @@
     // Misc methods
     function TestMask(Mask: QWord; BitIndex: Byte): Boolean;
-    procedure ReadItemByMaskIndex(Index: Integer; Data: TVarIntSerializer);
+    function BuildMask(Bits: array of Integer): Integer;
+    procedure ReadItemByMaskIndex(Index: Integer; Data: TVarBlockSerializer);
     procedure ReadItemRefByMaskIndex(Index: Integer; Data: TSubStream);
     procedure BlockEnclose;
     procedure BlockUnclose;
     constructor Create;
+    destructor Destroy; override;
+    property Stream: TStream read FStream write SetStream;
+  end;
+
+  { TVarBlockIndexed }
+
+  TVarBlockIndexed = class
+  private
+  public
+    Items: TObjectList; // TObjectList<TVarBlockSerializer>
+    Enclose: Boolean;
+    procedure CheckItem(Index: Integer);
+
+    // Base
+    procedure WriteVarUInt(Index: Integer; Value: QWord);
+    function ReadVarUInt(Index: Integer): QWord;
+    procedure WriteVarBlock(Index: Integer; Block: TVarBlockSerializer);
+    procedure ReadVarBlock(Index: Integer; Block: TVarBlockSerializer);
+    procedure WriteVarStream(Index: Integer; Stream: TStream);
+    procedure ReadVarStream(Index: Integer; Stream: TStream);
+    procedure WriteVarIndexedBlock(Index: Integer; Block: TVarBlockIndexed);
+    procedure ReadVarIndexedBlock(Index: Integer; Block: TVarBlockIndexed);
+
+    // Advanced data types
+    procedure WriteVarSInt(Index: Integer; Value: Int64);
+    function ReadVarSInt(Index: Integer): Int64;
+    procedure WriteVarFloat(Index: Integer; Value: Double);
+    function ReadVarFloat(Index: Integer): Double;
+    procedure WriteVarString(Index: Integer; Value: string);
+    function ReadVarString(Index: Integer): string;
+    procedure WriteVarIntegerArray(Index: Integer; List: TListInteger);
+    procedure ReadVarIntegerArray(Index: Integer; List: TListInteger);
+
+    procedure Clear;
+    function TestIndex(Index: Integer): Boolean;
+    procedure WriteToVarBlock(Stream: TVarBlockSerializer);
+    procedure ReadFromVarBlock(Stream: TVarBlockSerializer);
+    procedure WriteToStream(Stream: TStream);
+    procedure ReadFromStream(Stream: TStream);
+    constructor Create;
+    destructor Destroy; override;
   end;
 
 implementation
 
-{ TVarIntSerializer }
-
-procedure TVarIntSerializer.TrimLeft;
-var
-  Temp: TVarIntSerializer;
+resourcestring
+  SMaskedValueReadError = 'Error reading masked variable length block.';
+  SUInt64Overflow = '64-bit UInt read overflow.';
+
+{ TVarBlockSerializer }
+
+procedure TVarBlockSerializer.TrimLeft;
+var
+  Temp: TVarBlockSerializer;
   Length: Integer;
   Data: Byte;
-begin
-  Temp := TVarIntSerializer.Create;
-  Position := 0;
-  Length := Size * 8;
-  Data := 0;
-  while (Length > 0) and
-  (((Data shr (Length and 7)) and 1) = 0) do begin
-    Data := ReadByte;
-    Dec(Length); // set 7. bit in byte
-    while (((Data shr (Length and 7)) and 1) = 0) and ((Length and 7) > 0) do
-      Dec(Length);
-  end;
-  Inc(Length);
-  Length := Ceil(Length / 8);
-  Position := Size - Length;
-  ReadStream(TStream(Temp), Length);
-  Clear;
-  Position := 0;
-  WriteStream(Temp, Temp.Size);
-end;
-
-function TVarIntSerializer.GetUnaryLengthMask(Length: Integer): Byte;
+  StreamHelper: TStreamHelper;
+begin
+  try
+    Temp := TVarBlockSerializer.Create;
+    Stream.Position := 0;
+    Length := Stream.Size * 8;
+    Data := 0;
+    while (Length > 0) and
+    (((Data shr (Length and 7)) and 1) = 0) do begin
+      Data := Stream.ReadByte;
+      Dec(Length); // set 7. bit in byte
+      while (((Data shr (Length and 7)) and 1) = 0) and ((Length and 7) > 0) do
+        Dec(Length);
+    end;
+    Inc(Length);
+    Length := Ceil(Length / 8);
+    Stream.Position := Stream.Size - Length;
+    StreamHelper := TStreamHelper.Create(Stream);
+    StreamHelper.ReadStream(Temp.Stream, Length);
+    Temp.Stream.Size := 0;
+    Stream.Position := 0;
+    StreamHelper.WriteStream(Temp.Stream, Temp.Stream.Size);
+  finally
+    StreamHelper.Free;
+    Temp.Free;
+  end;
+end;
+
+procedure TVarBlockSerializer.SetStream(const AValue: TStream);
+begin
+  if OwnsStream and Assigned(FStream) then
+    FStream.Free;
+  OwnsStream := False;
+  FStream := AValue;
+end;
+
+function TVarBlockSerializer.GetUnaryLengthMask(Length: Integer): Byte;
 begin
   Result := ((1 shl (BitAlignment - Length)) - 1) xor $ff;
 end;
 
-function TVarIntSerializer.DecodeUnaryLength(Data:Byte):Integer;
+function TVarBlockSerializer.DecodeUnaryLength(Data:Byte):Integer;
 begin
   Result := 1;
@@ -92 +161 @@
 end;
 
-procedure TVarIntSerializer.WriteVarUInt(Value: QWord);
+procedure TVarBlockSerializer.WriteVarUInt(Value: QWord);
 var
   Length: Byte;
@@ -112 +181 @@
     if I = Length then Data := (Data and
       (LengthMask xor $ff)) or ((LengthMask shl 1) and $ff);
-    WriteByte(Data);
-  end;
-end;
-
-function TVarIntSerializer.ReadVarUInt: QWord;
+    Stream.WriteByte(Data);
+  end;
+end;
+
+function TVarBlockSerializer.ReadVarUInt: QWord;
 var
   Data: Byte;
@@ -127 +196 @@
   I := 0;
   while I < Length do begin
-    Data := ReadByte;
+    Data := Stream.ReadByte;
     if I = 0 then begin
       Length := DecodeUnaryLength(Data);
-      if Length > (BitAlignment - 1) then raise Exception.Create('64-bit UInt read overflow');
+      if Length > (BitAlignment) then
+        raise Exception.Create(SUInt64Overflow);
       LengthMask := GetUnaryLengthMask(Length);
       Data := Data and (LengthMask xor $ff);
     end;
-    Result := Result or (Data shl ((Length - I - 1) * BitAlignment));
+    Result := Result or (QWord(Data) shl ((Length - I - 1) * BitAlignment));
     Inc(I);
   end;
 end;
 
-procedure TVarIntSerializer.WriteVarFloat(Value: Double);
+procedure TVarBlockSerializer.WriteVarBlock(Block: TVarBlockSerializer);
+begin
+  WriteVarStream(Block.Stream);
+end;
+
+procedure TVarBlockSerializer.ReadVarBlock(Block: TVarBlockSerializer);
+begin
+  ReadVarStream(Block.Stream);
+end;
+
+procedure TVarBlockSerializer.WriteVarFloat(Value: Double);
 var
   Exponent: Integer;
-begin
-  // Normalize to integer number with base 10 exponent
-  Exponent := 0;
-  while Frac(Value) > 0 do begin
-    Value := Value * RealBase;
-    Dec(Exponent);
-  end;
-  while Frac(Value / RealBase) = 0 do begin
-    Value := Value / RealBase;
-    Inc(Exponent);
-  end;
-  WriteVarSInt(Trunc(Value));
-  WriteVarSInt(Exponent);
-end;
-
-function TVarIntSerializer.ReadVarFloat: Double;
+  Block: TVarBlockSerializer;
+begin
+  try
+    Block := TVarBlockSerializer.Create;
+
+    // Normalize to integer number with base 10 exponent
+    Exponent := 0;
+    while Frac(Value) > 0 do begin
+      Value := Value * RealBase;
+      Dec(Exponent);
+    end;
+    while Frac(Value / RealBase) = 0 do begin
+      Value := Value / RealBase;
+      Inc(Exponent);
+    end;
+    Block.WriteVarSInt(Trunc(Value));
+    Block.WriteVarSInt(Exponent);
+    WriteVarBlock(Block);
+  finally
+    Block.Free;
+  end;
+end;
+
+function TVarBlockSerializer.ReadVarFloat: Double;
 var
   Significant: Int64;
   Exponent: Integer;
-begin
-  Significant := ReadVarSInt;
-  Exponent := ReadVarSInt;
-  Result := Significant * IntPower(RealBase, Exponent);
-end;
-
-procedure TVarIntSerializer.WriteVarString(Value: string);
-var
-  Stream: TVarIntSerializer;
-  I: Integer;
-begin
-  Stream := TVarIntSerializer.Create;
-  for I := 1 to Length(Value) do
-    Stream.WriteVarUInt(Integer(Value[I]));
-  WriteVarBlock(Stream);
-  Stream.Destroy;
-end;
-
-function TVarIntSerializer.ReadVarString: string;
-var
-  Stream: TVarIntSerializer;
+  Block: TVarBlockSerializer;
+begin
+  try
+    Block := TVarBlockSerializer.Create;
+    ReadVarBlock(Block);
+    Significant := Block.ReadVarSInt;
+    Exponent := Block.ReadVarSInt;
+    Result := Significant * IntPower(RealBase, Exponent);
+  finally
+    Block.Free;
+  end;
+end;
+
+procedure TVarBlockSerializer.WriteVarString(Value: string);
+var
+  Stream: TVarBlockSerializer;
+  I: Integer;
+begin
+  try
+    Stream := TVarBlockSerializer.Create;
+    for I := 1 to Length(Value) do
+      Stream.WriteVarUInt(Integer(Value[I]));
+    WriteVarBlock(Stream);
+  finally
+    Stream.Free;
+  end;
+end;
+
+function TVarBlockSerializer.ReadVarString: string;
+var
+  Block: TVarBlockSerializer;
   Character: Integer;
 begin
-  Stream := TVarIntSerializer.Create;
-  ReadVarBlock(Stream);
-  Stream.Position := 0;
-  while Stream.Position < Stream.Size do begin
-    Character := Stream.ReadVarUInt;
-    Result := Result + Char(Character);
-  end;
-  Stream.Destroy;
-end;
-
-procedure TVarIntSerializer.WriteVarBlock(Stream: TStream);
+  try
+    Block := TVarBlockSerializer.Create;
+    ReadVarBlock(Block);
+    Block.Stream.Position := 0;
+    while Block.Stream.Position < Block.Stream.Size do begin
+      Character := Block.ReadVarUInt;
+      Result := Result + Char(Character);
+    end;
+  finally
+    Block.Free;
+  end;
+end;
+
+procedure TVarBlockSerializer.WriteVarStream(AStream: TStream);
 var
   Length: Integer; // Count of data bytes
@@ -201 +302 @@
   LengthMask: Byte;
 begin
-  Stream.Position := 0;
-  Length := Stream.Size;
+  AStream.Position := 0;
+  Length := AStream.Size;
 
   // Copy data
-  if Length = 0 then WriteByte(0)
+  if Length = 0 then Stream.WriteByte(0)
   else begin
-    if Stream.Size > 0 then Data := Stream.ReadByte
+    if AStream.Size > 0 then Data := AStream.ReadByte
       else Data := 0;
     if (Length < BitAlignment) then begin
@@ -217 +318 @@
         if Length < 8 then begin
           LengthMask := GetUnaryLengthMask(Length);
-          WriteByte((LengthMask shl 1) and $ff);
-          WriteByte(Data);
+          Stream.WriteByte((LengthMask shl 1) and $ff);
+          Stream.WriteByte(Data);
         end;
       end else begin
         // First data byte fit to length byte
-        WriteByte((Data and (LengthMask xor $ff)) or ((LengthMask shl 1) and $ff));
+        Stream.WriteByte((Data and (LengthMask xor $ff)) or ((LengthMask shl 1) and $ff));
       end;
     end;
     if Length >= BitAlignment then begin
       // Recursive length
-      WriteByte($ff);
-      WriteVarUInt(Stream.Size);
-      WriteByte(Data);
+      Stream.WriteByte($ff);
+      WriteVarUInt(AStream.Size);
+      Stream.WriteByte(Data);
     end;
 
     // Copy rest of data
-    for I := 1 to Stream.Size - 1 do begin
-      if I < Stream.Size then Data := Stream.ReadByte
+    for I := 1 to AStream.Size - 1 do begin
+      if I < AStream.Size then Data := AStream.ReadByte
         else Data := 0;
-      WriteByte(Data);
-    end;
-  end;
-end;
-
-procedure TVarIntSerializer.ReadVarBlock(Stream: TStream);
+      Stream.WriteByte(Data);
+    end;
+  end;
+end;
+
+procedure TVarBlockSerializer.ReadVarStream(AStream: TStream);
 var
   Data: Byte;
@@ -248 +349 @@
   LengthMask: Byte;
 begin
-  Stream.Size := 0;
+  AStream.Size := 0;
   I := 0;
   Length := 1;
   while I < Length do begin
-    Data := ReadByte;
+    Data := Stream.ReadByte;
     if I = 0 then begin
       if Data = $ff then begin
         // Read recursive length
         Length := ReadVarUInt;
-        Stream.Size := Length;
-        Data := ReadByte;
-        Stream.WriteByte(Data);
+        AStream.Size := Length;
+        Data := Stream.ReadByte;
+        AStream.WriteByte(Data);
       end else begin
         // Read unary length
         Length := DecodeUnaryLength(Data);
-        Stream.Size := Length;
+        AStream.Size := Length;
         LengthMask := GetUnaryLengthMask(Length);
         Data := Data and (LengthMask xor $ff);
         // Drop first byte if first data zero
-        if Data <> 0 then Stream.WriteByte(Data)
+        if Data <> 0 then AStream.WriteByte(Data)
           else begin
             Dec(Length);
-            Stream.Size := Length;
+            AStream.Size := Length;
             if Length > 0 then begin
-              Data := ReadByte;
-              Stream.WriteByte(Data);
+              Data := Stream.ReadByte;
+              AStream.WriteByte(Data);
             end;
           end;
       end;
-    end else Stream.WriteByte(Data);
+    end else AStream.WriteByte(Data);
     Inc(I);
   end;
-  Stream.Position := 0;
-end;
-
-function TVarIntSerializer.GetVarSize: Integer;
+  AStream.Position := 0;
+end;
+
+function TVarBlockSerializer.GetVarSize: Integer;
 var
   Data: Byte;
   StoredPosition: Integer;
 begin
-  StoredPosition := Position;
+  StoredPosition := Stream.Position;
   Result := 1; // Byte block length
-  Data := ReadByte;
+  Data := Stream.ReadByte;
   if Data = $ff then Result := ReadVarUInt + 2
   else begin
     Result := DecodeUnaryLength(Data);
   end;
-  Position := StoredPosition;
-end;
-
-procedure TVarIntSerializer.WriteVarSInt(Value: Int64);
+  Stream.Position := StoredPosition;
+end;
+
+procedure TVarBlockSerializer.WriteVarSInt(Value: Int64);
 begin
   if Value < 0 then WriteVarUInt(((-Value) shl 1) - 1)
@@ -304 +405 @@
 end;
 
-function TVarIntSerializer.ReadVarSInt: Int64;
+function TVarBlockSerializer.ReadVarSInt: Int64;
 begin
   Result := ReadVarUInt;
@@ -311 +412 @@
 end;
 
-function TVarIntSerializer.TestMask(Mask: QWord; BitIndex: Byte): Boolean;
+function TVarBlockSerializer.TestMask(Mask: QWord; BitIndex: Byte): Boolean;
 begin
   Result := ((Mask shr BitIndex) and 1) = 1;
 end;
 
-procedure TVarIntSerializer.ReadItemByMaskIndex(Index:Integer;Data:
-  TVarIntSerializer);
+function TVarBlockSerializer.BuildMask(Bits:array of Integer):Integer;
+var
+  I: Integer;
+begin
+  Result := 0;
+  for I := 0 to High(Bits) do
+    Result := Result or (1 shl Bits[I]);
+end;
+
+procedure TVarBlockSerializer.ReadItemByMaskIndex(Index:Integer; Data:
+  TVarBlockSerializer);
 var
   Mask: Integer;
   I: Integer;
-begin
-  Position := 0;
-  Data.Size := 0;
-  Mask := ReadVarUInt;
+  StreamHelper: TStreamHelper;
+begin
+  try
+    StreamHelper := TStreamHelper.Create(Stream);
+    try
+      Stream.Position := 0;
+      Data.Stream.Size := 0;
+      Mask := ReadVarUInt;
+      I := 0;
+      while (Stream.Position < Stream.Size) and (I < Index) do begin
+        if TestMask(Mask, I) then Stream.Position := Stream.Position + GetVarSize;
+        Inc(I);
+      end;
+      if TestMask(Mask, Index) then
+        StreamHelper.ReadStream(Data.Stream, GetVarSize);
+    except
+      raise Exception.Create(SMaskedValueReadError);
+    end;
+  finally
+    StreamHelper.Free;
+    Data.Stream.Position := 0;
+  end;
+end;
+
+procedure TVarBlockSerializer.ReadItemRefByMaskIndex(Index:Integer;Data:TSubStream
+  );
+var
+  Mask: Integer;
+  I: Integer;
+begin
+  try
+    Stream.Position := 0;
+    Data.Size := 0;
+    Mask := ReadVarUInt;
+    I := 0;
+    while (Stream.Position < Stream.Size) and (I < Index) do begin
+      if TestMask(Mask, I) then Stream.Position := Stream.Position + GetVarSize;
+      Inc(I);
+    end;
+    if TestMask(Mask, Index) then begin
+      if Stream is TSubStream then begin
+        // Recalculate substream
+        Data.Source := TSubStream(Stream).Source;
+        Data.SourcePosition := TSubStream(Stream).SourcePosition + Stream.Position;
+      end else begin
+        Data.Source := Self.Stream;
+        Data.SourcePosition := Stream.Position;
+      end;
+      Data.Size := GetVarSize;
+    end;
+    Data.Position := 0;
+  except
+    raise Exception.Create(SMaskedValueReadError);
+  end;
+end;
+
+procedure TVarBlockSerializer.BlockEnclose;
+var
+  Temp: TVarBlockSerializer;
+  StreamHelper: TStreamHelper;
+begin
+  try
+    Temp := TVarBlockSerializer.Create;
+    StreamHelper := TStreamHelper.Create(Temp.Stream);
+    StreamHelper.WriteStream(Stream, Stream.Size);
+    Stream.Size := 0;
+    WriteVarBlock(Temp);
+  finally
+    StreamHelper.Free;
+    Temp.Free;
+  end;
+end;
+
+procedure TVarBlockSerializer.BlockUnclose;
+var
+  Temp: TVarBlockSerializer;
+  StreamHelper: TStreamHelper;
+begin
+  try
+    Temp := TVarBlockSerializer.Create;
+    StreamHelper := TStreamHelper.Create(Stream);
+    ReadVarBlock(Temp);
+    Stream.Size := 0;
+    StreamHelper.WriteStream(Temp.Stream, Temp.Stream.Size);
+  finally
+    Stream.Position := 0;
+    StreamHelper.Free;
+    Temp.Free;
+  end;
+end;
+
+constructor TVarBlockSerializer.Create;
+begin
+  inherited Create;
+  Stream := TStreamHelper.Create;
+  OwnsStream := True;
+  TStreamHelper(Stream).Endianness := enBig;
+end;
+
+destructor TVarBlockSerializer.Destroy;
+begin
+  if OwnsStream then begin
+    Stream.Free;
+  end;
+  inherited Destroy;
+end;
+
+{ TVarBlockIndexed }
+
+procedure TVarBlockIndexed.CheckItem(Index:Integer);
+begin
+  if Items.Count > Index then begin
+    if not Assigned(Items[Index]) then
+      Items[Index] := TVarBlockSerializer.Create;
+    TVarBlockSerializer(Items[Index]).Stream.Size := 0;
+  end else begin
+    Items.Count := Index + 1;
+    Items[Index] := TVarBlockSerializer.Create;
+  end;
+end;
+
+procedure TVarBlockIndexed.WriteVarUInt(Index:Integer;Value:QWord);
+begin
+  CheckItem(Index);
+  TVarBlockSerializer(Items[Index]).WriteVarUInt(Value);
+end;
+
+function TVarBlockIndexed.ReadVarUInt(Index:Integer):QWord;
+begin
+  TVarBlockSerializer(Items[Index]).Stream.Position := 0;
+  Result := TVarBlockSerializer(Items[Index]).ReadVarUInt;
+end;
+
+procedure TVarBlockIndexed.WriteVarBlock(Index: Integer; Block: TVarBlockSerializer);
+begin
+  CheckItem(Index);
+  TVarBlockSerializer(Items[Index]).WriteVarBlock(Block);
+end;
+
+procedure TVarBlockIndexed.ReadVarBlock(Index: Integer; Block: TVarBlockSerializer);
+begin
+  TVarBlockSerializer(Items[Index]).Stream.Position := 0;
+  TVarBlockSerializer(Items[Index]).ReadVarBlock(Block);
+end;
+
+procedure TVarBlockIndexed.WriteVarStream(Index: Integer; Stream: TStream);
+begin
+  CheckItem(Index);
+  TVarBlockSerializer(Items[Index]).WriteVarStream(Stream);
+end;
+
+procedure TVarBlockIndexed.ReadVarStream(Index: Integer; Stream: TStream);
+begin
+  TVarBlockSerializer(Items[Index]).Stream.Position := 0;
+  TVarBlockSerializer(Items[Index]).ReadVarStream(Stream);
+end;
+
+procedure TVarBlockIndexed.WriteVarIndexedBlock(Index: Integer;
+  Block: TVarBlockIndexed);
+var
+  Temp: TStreamHelper;
+begin
+  try
+    Temp := TStreamHelper.Create;
+    Block.Enclose := False;
+    Block.WriteToStream(Temp);
+    WriteVarStream(Index, Temp);
+  finally
+    Temp.Free;
+  end;
+end;
+
+procedure TVarBlockIndexed.ReadVarIndexedBlock(Index: Integer;
+  Block: TVarBlockIndexed);
+var
+  Temp: TStreamHelper;
+begin
+  try
+    Temp := TStreamHelper.Create;
+    Block.Enclose := False;
+    ReadVarStream(Index, Temp);
+    Block.ReadFromStream(Temp);
+  finally
+    Temp.Free;
+  end;
+end;
+
+procedure TVarBlockIndexed.WriteVarSInt(Index: Integer; Value:Int64);
+begin
+  CheckItem(Index);
+  TVarBlockSerializer(Items[Index]).WriteVarSInt(Value);
+end;
+
+function TVarBlockIndexed.ReadVarSInt(Index: Integer): Int64;
+begin
+  TVarBlockSerializer(Items[Index]).Stream.Position := 0;
+  Result := TVarBlockSerializer(Items[Index]).ReadVarSInt;
+end;
+
+procedure TVarBlockIndexed.WriteVarFloat(Index: Integer; Value:Double);
+begin
+  CheckItem(Index);
+  TVarBlockSerializer(Items[Index]).WriteVarFloat(Value);
+end;
+
+function TVarBlockIndexed.ReadVarFloat(Index: Integer):Double;
+begin
+  TVarBlockSerializer(Items[Index]).Stream.Position := 0;
+  Result := TVarBlockSerializer(Items[Index]).ReadVarFloat;
+end;
+
+procedure TVarBlockIndexed.WriteVarString(Index: Integer; Value:string);
+begin
+  CheckItem(Index);
+  TVarBlockSerializer(Items[Index]).WriteVarString(Value);
+end;
+
+function TVarBlockIndexed.ReadVarString(Index: Integer):string;
+begin
+  TVarBlockSerializer(Items[Index]).Stream.Position := 0;
+  Result := TVarBlockSerializer(Items[Index]).ReadVarString;
+end;
+
+procedure TVarBlockIndexed.WriteVarIntegerArray(Index: Integer;
+  List: TListInteger);
+var
+  I: Integer;
+  Temp: TVarBlockSerializer;
+begin
+  try
+    Temp := TVarBlockSerializer.Create;
+    for I := 0 to List.Count - 1 do
+      Temp.WriteVarUInt(Integer(List[I]));
+    WriteVarBlock(Index, Temp);
+  finally
+    Temp.Free;
+  end;
+end;
+
+procedure TVarBlockIndexed.ReadVarIntegerArray(Index: Integer;
+  List: TListInteger);
+var
+  Temp: TVarBlockSerializer;
+begin
+  try
+    Temp := TVarBlockSerializer.Create;
+    List.Clear;
+    ReadVarBlock(Index, Temp);
+    while Temp.Stream.Position < Temp.Stream.Size do begin
+      List.Add(Temp.ReadVarUInt);
+    end;
+  finally
+    Temp.Free;
+  end;
+end;
+
+procedure TVarBlockIndexed.Clear;
+begin
+  Items.Clear;
+end;
+
+function TVarBlockIndexed.TestIndex(Index:Integer):Boolean;
+begin
+  if (Index >= 0) and (Index < Items.Count) then
+    Result := Assigned(Items[Index])
+    else Result := False
+end;
+
+procedure TVarBlockIndexed.WriteToVarBlock(Stream: TVarBlockSerializer);
+var
+  Mask: Integer;
+  I: Integer;
+  StreamHelper: TStreamHelper;
+begin
+  try
+    StreamHelper := TStreamHelper.Create(Stream.Stream);
+    Stream.Stream.Size := 0;
+    Mask := 0;
+    for I := 0 to Items.Count - 1 do
+      if Assigned(Items[I]) then Mask := Mask or (1 shl I);
+    Stream.WriteVarUInt(Mask);
+    for I := 0 to Items.Count - 1 do
+      if Assigned(Items[I]) then StreamHelper.WriteStream(TVarBlockSerializer(Items[I]).Stream,
+        TVarBlockSerializer(Items[I]).Stream.Size);
+    if Enclose then Stream.BlockEnclose;
+  finally
+    StreamHelper.Free;
+  end;
+end;
+
+procedure TVarBlockIndexed.ReadFromVarBlock(Stream: TVarBlockSerializer);
+var
+  Mask: Integer;
+  I: Integer;
+begin
+  if Enclose then Stream.BlockUnclose;
+  Stream.Stream.Position := 0;
+  Mask := Stream.ReadVarUInt;
   I := 0;
-  while (Position < Size) and (I < Index) do begin
-    if TestMask(Mask, I) then Position := Position + GetVarSize;
+  while Mask <> 0 do begin
+    if Stream.TestMask(Mask, I) then begin
+      if Items.Count <= I then Items.Count := I + 1;
+      Items[I] := TVarBlockSerializer.Create;
+      Stream.ReadItemByMaskIndex(I, TVarBlockSerializer(Items[I]));
+      Mask := Mask xor (1 shl I); // Clear bit on current index
+    end;
     Inc(I);
   end;
-  if TestMask(Mask, Index) then
-    ReadStream(TStream(Data), GetVarSize);
-  Data.Position := 0;
-end;
-
-procedure TVarIntSerializer.ReadItemRefByMaskIndex(Index:Integer;Data:TSubStream
-  );
-var
-  Mask: Integer;
-  I: Integer;
-begin
-  Position := 0;
-  Data.Size := 0;
-  Mask := ReadVarUInt;
-  I := 0;
-  while (Position < Size) and (I < Index) do begin
-    if TestMask(Mask, I) then Position := Position + GetVarSize;
-    Inc(I);
-  end;
-  if TestMask(Mask, Index) then begin
-    if TStream(Self) is TSubStream then begin
-      // Recalculate substream
-      Data.Source := TSubStream(Self).Source;
-      Data.SourcePosition := TSubStream(Self).SourcePosition + Position;
-    end else begin
-      Data.Source := Self;
-      Data.SourcePosition := Position;
-    end;
-    Data.Size := GetVarSize;
-  end;
-  Data.Position := 0;
-end;
-
-procedure TVarIntSerializer.BlockEnclose;
-var
-  Temp: TVarIntSerializer;
-begin
-  Temp := TVarIntSerializer.Create;
-  Temp.WriteStream(Self, Size);
-  Clear;
-  WriteVarBlock(Temp);
-  Temp.Destroy;
-end;
-
-procedure TVarIntSerializer.BlockUnclose;
-var
-  Temp: TVarIntSerializer;
-begin
-  Temp := TVarIntSerializer.Create;
-  ReadVarBlock(Temp);
-  Clear;
-  WriteStream(Temp, Temp.Size);
-  Temp.Destroy;
-  Position := 0;
-end;
-
-constructor TVarIntSerializer.Create;
-begin
-  inherited Create;
-  Endianness := enBig;
+end;
+
+procedure TVarBlockIndexed.WriteToStream(Stream: TStream);
+var
+  Temp: TVarBlockSerializer;
+  StreamHelper: TStreamHelper;
+begin
+  try
+    Temp := TVarBlockSerializer.Create;
+    StreamHelper := TStreamHelper.Create(Stream);
+    WriteToVarBlock(Temp);
+    StreamHelper.WriteStream(Temp.Stream, Temp.Stream.Size);
+  finally
+    StreamHelper.Free;
+    Temp.Free;
+  end;
+end;
+
+procedure TVarBlockIndexed.ReadFromStream(Stream: TStream);
+var
+  VarBlock: TVarBlockSerializer;
+begin
+  try
+    VarBlock := TVarBlockSerializer.Create;
+    VarBlock.Stream := Stream;
+    ReadFromVarBlock(VarBlock);
+  finally
+    VarBlock.Free;
+  end;
+end;
+
+constructor TVarBlockIndexed.Create;
+begin
+  Items := TObjectList.Create;
+  Enclose := True;
+end;
+
+destructor TVarBlockIndexed.Destroy;
+begin
+  Items.Free;
+  inherited Destroy;
 end;