unit Myc.Ast.Closure;

interface

uses
    System.Classes,
    System.Generics.Collections,
    Myc.Data.Types,
    Myc.Ast,
    Myc.Ast.Scope;

type
    // A closure is a specific kind of method value that is defined by the evaluator.
    // It holds the AST body and its captured scope.
    IDataClosureValue = interface(IDataMethodValue)
        ['{2704586B-E4BD-47AA-B05D-FD441AE6D818}']
        {$region 'private'}
        function GetBody: IExpressionNode;
        function GetParameters: TList<IIdentifierNode>;
        function GetClosureScope: TExecutionScope;
        {$endregion}
        property Body: IExpressionNode read GetBody;
        property Parameters: TList<IIdentifierNode> read GetParameters;
        property ClosureScope: TExecutionScope read GetClosureScope;
    end;

// Factory function to create a new closure value.
function CreateDataClosureValue(
    AMethodType: IDataMethodType;
    ABody: IExpressionNode;
    AParameters: TList<IIdentifierNode>;
    AClosureScope: TExecutionScope
): IDataClosureValue;

implementation

uses
    System.SysUtils;

type
    { TDataClosureValueImpl }
    // Concrete implementation of the IDataClosureValue interface.
    TDataClosureValueImpl = class(TInterfacedObject, IDataValue, IDataClosureValue)
    private
        FMethodType: IDataMethodType;
        FBody: IExpressionNode;
        FParameters: TList<IIdentifierNode>;
        FClosureScope: TExecutionScope;
        // IDataValue
        function GetDataType: IDataType;
        function GetAsString: string;
        // IDataMethodValue
        function GetValue: TDataMethodProc;
        // IDataClosureValue
        function GetBody: IExpressionNode;
        function GetParameters: TList<IIdentifierNode>;
        function GetClosureScope: TExecutionScope;
    public
        constructor Create(
            AMethodType: IDataMethodType;
            ABody: IExpressionNode;
            AParameters: TList<IIdentifierNode>;
            ACClosureScope: TExecutionScope
        );
    end;

function CreateDataClosureValue(
    AMethodType: IDataMethodType;
    ABody: IExpressionNode;
    AParameters: TList<IIdentifierNode>;
    AClosureScope: TExecutionScope
): IDataClosureValue;
begin
    Result := TDataClosureValueImpl.Create(AMethodType, ABody, AParameters, AClosureScope);
end;

{ TDataClosureValueImpl }

constructor TDataClosureValueImpl.Create(
    AMethodType: IDataMethodType;
    ABody: IExpressionNode;
    AParameters: TList<IIdentifierNode>;
    ACClosureScope: TExecutionScope
);
begin
    inherited Create;
    FMethodType := AMethodType;
    FBody := ABody;
    FParameters := AParameters; // Note: We are taking ownership of the list reference
    FClosureScope := ACClosureScope;
end;

function TDataClosureValueImpl.GetAsString: string;
begin
    Result := '<CLOSURE>';
end;

function TDataClosureValueImpl.GetBody: IExpressionNode;
begin
    Result := FBody;
end;

function TDataClosureValueImpl.GetClosureScope: TExecutionScope;
begin
    Result := FClosureScope;
end;

function TDataClosureValueImpl.GetDataType: IDataType;
begin
    Result := FMethodType;
end;

function TDataClosureValueImpl.GetParameters: TList<IIdentifierNode>;
begin
    Result := FParameters;
end;

function TDataClosureValueImpl.GetValue: TDataMethodProc;
begin
    // This direct execution path is no longer used for closures.
    raise ENotSupportedException.Create('Cannot get raw method proc from a closure object.');
end;

end.