MycLib/Src/AST/Myc.Ast.Nodes.pas

unit Myc.Ast.Nodes;

interface

uses
    System.SysUtils,
    System.Generics.Collections,
    Myc.Data.POD;

type
    // Operators and helpers
    TBinaryOperator = (boAdd, boSubtract, boMultiply, boDivide, boEqual, boNotEqual, boLess, boGreater, boLessOrEqual, boGreaterOrEqual);
    TUnaryOperator = (uoNegate, uoNot);

    TBinaryOperatorHelper = record helper for TBinaryOperator
        function ToString: string;
    end;

    TUnaryOperatorHelper = record helper for TUnaryOperator
        function ToString: string;
    end;

    // Added avkText to represent a string value.
    TAstValueKind = (avkUndefined, avkScalar, avkClosure, avkText);

    // --- Forward Declarations to break cycles ---
    IExecutionScope = interface;
    IAstVisitor = interface;
    IAstNode = interface;
    IExpressionNode = interface;
    IIdentifierNode = interface;
    IConstantNode = interface;
    IBinaryExpressionNode = interface;
    IUnaryExpressionNode = interface;
    IIfExpressionNode = interface;
    // Added forward declaration for the new ternary expression node.
    ITernaryExpressionNode = interface;
    ILambdaExpressionNode = interface;
    IFunctionCallNode = interface;
    IBlockExpressionNode = interface;
    IVariableDeclarationNode = interface;
    IAssignmentNode = interface;
    IEvaluatorClosure = interface;

    // --- Concrete Type Definitions ---

    IEvaluatorClosure = interface(IInterface)
        {$region 'private'}
        function GetBody: IExpressionNode;
        function GetParameters: TArray<IIdentifierNode>;
        function GetClosureScope: IExecutionScope;
        {$endregion}
        property Body: IExpressionNode read GetBody;
        property Parameters: TArray<IIdentifierNode> read GetParameters;
        property ClosureScope: IExecutionScope read GetClosureScope;
    end;

    TAstValue = record
    private
        type
            IVal<T> = interface
                ['{70210CAF-0857-4BF1-8254-B8239A155A02}']
                function GetValue: T;
                property Value: T read GetValue;
            end;

            TVal<T> = class(TInterfacedObject, IVal<T>)
            private
                FValue: T;
                function GetValue: T;
            public
                constructor Create(const AValue: T);
            end;

        var
            FKind: TAstValueKind;
            FScalar: TScalar;
            FInterface: IInterface;
        function GetKind: TAstValueKind; inline;
        function GetIsVoid: Boolean; inline;
    public
        class operator Initialize(out Dest: TAstValue);
        class function Void: TAstValue; static;
        class function FromScalar(const AValue: TScalar): TAstValue; static;
        class function FromClosure(const AValue: IEvaluatorClosure): TAstValue; static;
        class function FromText(const AValue: String): TAstValue; static;
        function AsScalar: TScalar;
        function AsClosure: IEvaluatorClosure;
        function AsText: String;
        function ToString: String;
        property IsVoid: Boolean read GetIsVoid;
        property Kind: TAstValueKind read GetKind;
    end;

    IExecutionScope = interface(IInterface)
        {$region 'private'}
        function GetParent: IExecutionScope;
        {$endregion}
        procedure Clear;
        function FindValue(const Name: string; out Value: TAstValue): Boolean;
        procedure SetValue(const Name: string; const Value: TAstValue);
        procedure AssignValue(const Name: string; const Value: TAstValue);
        function Dump: string;
        property Parent: IExecutionScope read GetParent;
    end;

    IAstVisitor = interface
        ['{A58B0A8E-F438-4217-A964-6E35624A9A4A}']
        function VisitConstant(const Node: IConstantNode): TAstValue;
        function VisitIdentifier(const Node: IIdentifierNode): TAstValue;
        function VisitBinaryExpression(const Node: IBinaryExpressionNode): TAstValue;
        function VisitUnaryExpression(const Node: IUnaryExpressionNode): TAstValue;
        function VisitIfExpression(const Node: IIfExpressionNode): TAstValue;
        // Added visitor method for the new ternary expression node.
        function VisitTernaryExpression(const Node: ITernaryExpressionNode): TAstValue;
        function VisitLambdaExpression(const Node: ILambdaExpressionNode): TAstValue;
        function VisitFunctionCall(const Node: IFunctionCallNode): TAstValue;
        function VisitBlockExpression(const Node: IBlockExpressionNode): TAstValue;
        function VisitVariableDeclaration(const Node: IVariableDeclarationNode): TAstValue;
        function VisitAssignment(const Node: IAssignmentNode): TAstValue;
    end;

    IAstNode = interface(IInterface)
        function Accept(const Visitor: IAstVisitor): TAstValue;
    end;

    IExpressionNode = interface(IAstNode)
    end;

    IConstantNode = interface(IExpressionNode)
        {$region 'private'}
        function GetValue: TScalar;
        {$endregion}
        property Value: TScalar read GetValue;
    end;

    IIdentifierNode = interface(IExpressionNode)
        {$region 'private'}
        function GetName: string;
        {$endregion}
        property Name: string read GetName;
    end;

    IBinaryExpressionNode = interface(IExpressionNode)
        {$region 'private'}
        function GetLeft: IExpressionNode;
        function GetOperator: TBinaryOperator;
        function GetRight: IExpressionNode;
        {$endregion}
        property Left: IExpressionNode read GetLeft;
        property Operator: TBinaryOperator read GetOperator;
        property Right: IExpressionNode read GetRight;
    end;

    IUnaryExpressionNode = interface(IExpressionNode)
        {$region 'private'}
        function GetOperator: TUnaryOperator;
        function GetRight: IExpressionNode;
        {$endregion}
        property Operator: TUnaryOperator read GetOperator;
        property Right: IExpressionNode read GetRight;
    end;

    // Represents an if-statement for control flow.
    IIfExpressionNode = interface(IExpressionNode)
        {$region 'private'}
        function GetCondition: IExpressionNode;
        function GetThenBranch: IExpressionNode;
        function GetElseBranch: IExpressionNode;
        {$endregion}
        property Condition: IExpressionNode read GetCondition;
        property ThenBranch: IExpressionNode read GetThenBranch;
        property ElseBranch: IExpressionNode read GetElseBranch;
    end;

    // Represents a ternary expression (e.g., condition ? true_expr : false_expr) for value selection.
    ITernaryExpressionNode = interface(IExpressionNode)
        {$region 'private'}
        function GetCondition: IExpressionNode;
        function GetThenBranch: IExpressionNode;
        function GetElseBranch: IExpressionNode;
        {$endregion}
        property Condition: IExpressionNode read GetCondition;
        property ThenBranch: IExpressionNode read GetThenBranch;
        property ElseBranch: IExpressionNode read GetElseBranch;
    end;

    ILambdaExpressionNode = interface(IExpressionNode)
        {$region 'private'}
        function GetParameters: TArray<IIdentifierNode>;
        function GetBody: IExpressionNode;
        {$endregion}
        property Parameters: TArray<IIdentifierNode> read GetParameters;
        property Body: IExpressionNode read GetBody;
    end;

    IFunctionCallNode = interface(IExpressionNode)
        {$region 'private'}
        function GetCallee: IExpressionNode;
        function GetArguments: TList<IExpressionNode>;
        {$endregion}
        property Callee: IExpressionNode read GetCallee;
        property Arguments: TList<IExpressionNode> read GetArguments;
    end;

    IBlockExpressionNode = interface(IExpressionNode)
        {$region 'private'}
        function GetExpressions: TList<IExpressionNode>;
        {$endregion}
        property Expressions: TList<IExpressionNode> read GetExpressions;
    end;

    IVariableDeclarationNode = interface(IExpressionNode)
        {$region 'private'}
        function GetIdentifier: IIdentifierNode;
        function GetInitializer: IExpressionNode;
        {$endregion}
        property Identifier: IIdentifierNode read GetIdentifier;
        property Initializer: IExpressionNode read GetInitializer;
    end;

    IAssignmentNode = interface(IExpressionNode)
        {$region 'private'}
        function GetIdentifier: IIdentifierNode;
        function GetValue: IExpressionNode;
        {$endregion}
        property Identifier: IIdentifierNode read GetIdentifier;
        property Value: IExpressionNode read GetValue;
    end;

implementation

uses
    System.Classes;

{ TAstValue }

constructor TAstValue.TVal<T>.Create(const AValue: T);
begin
    inherited Create;
    FValue := AValue;
end;

function TAstValue.TVal<T>.GetValue: T;
begin
    Result := FValue;
end;

{ TAstValue }

class operator TAstValue.Initialize(out Dest: TAstValue);
begin
    Dest.FKind := avkUndefined;
    Dest.FInterface := nil;
end;

function TAstValue.AsClosure: IEvaluatorClosure;
begin
    if (FKind <> avkClosure) then
        raise EInvalidCast.Create('Cannot read value as a Closure.');
    Result := IEvaluatorClosure(FInterface);
end;

function TAstValue.AsScalar: TScalar;
begin
    if (FKind <> avkScalar) then
        raise EInvalidCast.Create('Cannot read value as a Scalar.');
    Result := FScalar;
end;

function TAstValue.AsText: String;
begin
    if (FKind <> avkText) then
        raise EInvalidCast.Create('Cannot read value as Text.');

    Result := (FInterface as IVal<String>).Value;
end;

class function TAstValue.FromClosure(const AValue: IEvaluatorClosure): TAstValue;
begin
    Result.FKind := avkClosure;
    Result.FInterface := AValue;
    Result.FScalar := Default(TScalar);
end;

class function TAstValue.FromScalar(const AValue: TScalar): TAstValue;
begin
    Result.FKind := avkScalar;
    Result.FScalar := AValue;
    Result.FInterface := nil;
end;

class function TAstValue.FromText(const AValue: String): TAstValue;
begin
    Result.FKind := avkText;
    Result.FInterface := TVal<String>.Create(AValue);
    Result.FScalar := Default(TScalar);
end;

function TAstValue.GetIsVoid: Boolean;
begin
    Result := FKind = avkUndefined;
end;

function TAstValue.GetKind: TAstValueKind;
begin
    Result := FKind;
end;

function TAstValue.ToString: String;
begin
    case FKind of
        avkScalar: Result := FScalar.ToString;
        avkClosure: Result := '<closure>';
        avkText: Result := AsText;
        avkUndefined: Result := '<void>';
    else
        Result := '[Unknown AstValue]';
    end;
end;

class function TAstValue.Void: TAstValue;
begin
    Result := Default(TAstValue);
end;

{ TBinaryOperatorHelper }

function TBinaryOperatorHelper.ToString: string;
begin
    case Self of
        boAdd: Result := '+';
        boSubtract: Result := '-';
        boMultiply: Result := '*';
        boDivide: Result := '/';
        boEqual: Result := '==';
        boNotEqual: Result := '!=';
        boLess: Result := '<';
        boGreater: Result := '>';
        boLessOrEqual: Result := '<=';
        boGreaterOrEqual: Result := '>=';
    else
        Result := '?';
    end;
end;

{ TUnaryOperatorHelper }

function TUnaryOperatorHelper.ToString: string;
begin
    case Self of
        uoNegate: Result := '-';
        uoNot: Result := 'not';
    else
        Result := '?';
    end;
end;

end.