variant的序列和还原

variant的序列和还原

variant是delphi的万能数据类型，所以先要判断它存储的是哪种类型的数据。

不同类型的数据，要不同地处理。

procedure TMsgPack.SetAsVariant(const Value: Variant);
var
  I: Integer;
  AType: TVarType;
  procedure VarAsBytes;
  var
    L: Integer;
    p: PByte;
  begin
    FDataType := mptBinary;
    L := VarArrayHighBound(Value, 1) + 1;
    SetLength(FValue, L);
    p := VarArrayLock(Value);
    Move(p^, FValue[0], L);
    VarArrayUnlock(Value);
  end;
begin
  if VarIsArray(Value) then
  begin
    AType := VarType(Value);
    if (AType and varTypeMask) = varByte then
      VarAsBytes
    else
    begin
      checkObjectDataType(mptArray);
      ClearAndFreeAllChildren;
      for I := VarArrayLowBound(Value, VarArrayDimCount(Value))
        to VarArrayHighBound(Value, VarArrayDimCount(Value)) do
        Add.AsVariant := Value[I];
    end;
  end
  else
  begin
    case VarType(Value) of
      varSmallInt, varInteger, varByte, varShortInt, varWord,
        varLongWord, varInt64:
        AsInteger := Value;
      varSingle, varDouble, varCurrency:
        AsFloat := Value;
      varDate:
        AsDateTime := Value;
      varOleStr, varString{$IFDEF UNICODE}, varUString{$ENDIF}:
        AsString := Value;
      varBoolean:
        AsBoolean := Value;
      varNull,varEmpty,varUnknown:
        begin
          FDataType:=mptNull;
          SetLength(FValue, 0);
        end;
      {$IF RtlVersion>=26}
      varUInt64:
        AsInteger := Value;
      {$IFEND}
    else
      // null
      ;//raise Exception.Create(SVariantConvertNotSupport);
    end;
  end;
end;

　　

function TMsgPack.GetAsVariant: Variant;
var
  I: Integer;
  procedure BytesAsVariant;
  var
    L: Integer;
    p:PByte;
  begin
    L := Length(FValue);
    Result := VarArrayCreate([0, L - 1], varByte);
    p:=VarArrayLock(Result);
    Move(FValue[0],p^,L);
    VarArrayUnlock(Result);
  end;

begin
  case FDataType of
    mptNull:
      Result := null;
    mptString:
      Result := AsString;
    mptInteger:
      Result := AsInteger;
    mptFloat:
      Result := AsFloat;
    mptSingle:
      Result := AsSingle;
    mptDateTime:
      Result := AsDateTime;
    mptBoolean:
      Result := AsBoolean;
    mptArray, mptMap:
      begin
        Result := VarArrayCreate([0, Count - 1], varVariant);
        for I := 0 to Count - 1 do
          Result[I] := TMsgPack(FChildren[I]).AsVariant;
      end;
    mptBinary:
      BytesAsVariant;
  else
    raise Exception.Create(SVariantConvertNotSupport);
  end;
end;