unit Myc.Data.Types.Tuple;

interface

uses
    System.SysUtils,
    Myc.Data.Types;

type
    // Implements the simple tuple data value.
    TImplDataTupleValue = class(TInterfacedObject, IDataValue, IDataTupleValue)
    private
        FItems: TArray<IDataValue>;
        function GetDataType: IDataType;
        function GetAsString: string;
        function GetItemCount: Integer;
        function GetItem(Idx: Integer): IDataValue;
    public
        constructor Create(const AItems: array of IDataValue);
    end;

    // Implements the singleton tuple data type.
    TImplDataTupleType = class(TInterfacedObject, IDataType, IDataTupleType)
    strict private
        class var
            FSingleton: IDataTupleType;
        class constructor CreateClass;
    private
        function GetName: String;
        function GetKind: TDataKind;
    public
        function CreateValue(const AItems: array of IDataValue): IDataTupleValue;
        class property Singleton: IDataTupleType read FSingleton;
    end;

implementation

{ TImplDataTupleValue }

constructor TImplDataTupleValue.Create(const AItems: array of IDataValue);
var
    i: Integer;
begin
    inherited Create;
    SetLength(FItems, Length(AItems));
    for i := 0 to High(AItems) do
        FItems[i] := AItems[i];
end;

function TImplDataTupleValue.GetDataType: IDataType;
begin
    Result := TImplDataTupleType.Singleton;
end;

function TImplDataTupleValue.GetAsString: string;
var
    sb: TStringBuilder;
    i: Integer;
begin
    sb := TStringBuilder.Create;
    try
        sb.Append('(');
        for i := 0 to High(FItems) do
        begin
            sb.Append(FItems[i].AsString);
            if (i < High(FItems)) then
                sb.Append(', ');
        end;
        sb.Append(')');
        Result := sb.ToString;
    finally
        sb.Free;
    end;
end;

function TImplDataTupleValue.GetItem(Idx: Integer): IDataValue;
begin
    Result := FItems[Idx];
end;

function TImplDataTupleValue.GetItemCount: Integer;
begin
    Result := Length(FItems);
end;

{ TImplDataTupleType }

class constructor TImplDataTupleType.CreateClass;
begin
    FSingleton := TImplDataTupleType.Create;
end;

function TImplDataTupleType.CreateValue(const AItems: array of IDataValue): IDataTupleValue;
begin
    Result := TImplDataTupleValue.Create(AItems);
end;

function TImplDataTupleType.GetName: String;
begin
    Result := 'Tuple';
end;

function TImplDataTupleType.GetKind: TDataKind;
begin
    Result := dkTuple;
end;

end.