Michael Schimmel
103 lines
3.0 KiB
ObjectPascal
103 lines
3.0 KiB
ObjectPascal
unit Myc.Ast.Compiler.Lowering;
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interface
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uses
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System.SysUtils,
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System.Classes,
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System.Generics.Collections,
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Myc.Data.Scalar,
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Myc.Data.Value,
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Myc.Ast.Nodes, // Provides EAstException
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Myc.Ast.Visitor,
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Myc.Ast.Scope,
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Myc.Ast.Types,
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Myc.Ast;
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type
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// Exception specific to AST lowering/rewriting errors
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ELoweringException = class(EAstException);
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IAstLowerer = interface(IAstVisitor)
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function Execute(const RootNode: IAstNode): IAstNode;
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end;
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// This transformer runs *after* TypeChecker (Phase 3).
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// It "lowers" the AST by rewriting complex nodes into simpler ones
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// that the evaluator can understand (e.g., operator folding).
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TAstLowerer = class(TAstTransformer, IAstLowerer)
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private
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FBinaryOperators: TDictionary<string, TScalar.TBinaryOp>;
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FUnaryOperators: TDictionary<string, TScalar.TUnaryOp>;
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protected
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// Implement Visit methods here when specific lowering logic is added
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// (e.g. converting operator function calls to specific node types if added in future)
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public
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constructor Create;
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destructor Destroy; override;
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function Execute(const RootNode: IAstNode): IAstNode;
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class function Lower(const RootNode: IAstNode): IAstNode; static;
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end;
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implementation
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uses
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System.Generics.Defaults,
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Myc.Data.Keyword;
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{ TAstLowerer }
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constructor TAstLowerer.Create;
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begin
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inherited Create;
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// Operator folding maps (Reserved for future static optimization)
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FBinaryOperators := TDictionary<string, TScalar.TBinaryOp>.Create;
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FBinaryOperators.Add('+', TScalar.TBinaryOp.Add);
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FBinaryOperators.Add('-', TScalar.TBinaryOp.Subtract);
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FBinaryOperators.Add('*', TScalar.TBinaryOp.Multiply);
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FBinaryOperators.Add('/', TScalar.TBinaryOp.Divide);
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FBinaryOperators.Add('=', TScalar.TBinaryOp.Equal);
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FBinaryOperators.Add('<>', TScalar.TBinaryOp.NotEqual);
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FBinaryOperators.Add('<', TScalar.TBinaryOp.Less);
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FBinaryOperators.Add('<=', TScalar.TBinaryOp.LessOrEqual);
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FBinaryOperators.Add('>', TScalar.TBinaryOp.Greater);
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FBinaryOperators.Add('>=', TScalar.TBinaryOp.GreaterOrEqual);
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FUnaryOperators := TDictionary<string, TScalar.TUnaryOp>.Create;
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FUnaryOperators.Add('not', TScalar.TUnaryOp.Not);
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end;
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destructor TAstLowerer.Destroy;
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begin
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FUnaryOperators.Free;
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FBinaryOperators.Free;
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inherited;
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end;
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class function TAstLowerer.Lower(const RootNode: IAstNode): IAstNode;
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begin
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var lowerer := TAstLowerer.Create as IAstLowerer;
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try
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Result := lowerer.Execute(RootNode);
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except
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on E: Exception do
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raise ELoweringException.Create('Internal Error during AST Lowering: ' + E.Message);
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end;
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end;
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function TAstLowerer.Execute(const RootNode: IAstNode): IAstNode;
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begin
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if not Assigned(RootNode) then
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exit(nil);
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Result := Accept(RootNode);
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if not Assigned(Result) then
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Result := TAst.Block([]);
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end;
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end.
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