Michael Schimmel
291 lines
11 KiB
ObjectPascal
291 lines
11 KiB
ObjectPascal
unit Test.Ast.Interpreter.Scope;
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interface
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uses
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Myc.Ast,
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Myc.Ast.Nodes,
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Myc.Ast.Binding,
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Myc.Ast.Evaluator,
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Myc.Ast.Scope,
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Myc.Data.Scalar,
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Myc.Data.Value,
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DUnitX.TestFramework;
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type
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[TestFixture]
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TInterpreterScopeTests = class(TObject)
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private
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FGlobalScope: IExecutionScope;
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function Execute(const ANode: IAstNode): TDataValue;
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public
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[Setup]
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procedure Setup;
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[TearDown]
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procedure TearDown;
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[Test]
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procedure Test_DeeplyNestedLambda_ModifiesUpvalue;
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[Test]
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procedure Test_SeparateClosures_ShareSameUpvalue;
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[Test]
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procedure Test_NestedLambda_CapturesParameter;
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[Test]
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procedure Test_VariableShadowing_DoesNotAffectUpvalue;
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[Test]
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procedure Test_CaptureFromGlobalScope;
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[Test]
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procedure Test_ClosureCaptureWithParentScopeReallocation;
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end;
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implementation
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{ TInterpreterScopeTests }
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function TInterpreterScopeTests.Execute(const ANode: IAstNode): TDataValue;
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var
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binder: IAstBinder;
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boundNode: IAstNode;
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descriptor: IScopeDescriptor;
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runtimeScope: IExecutionScope;
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visitor: IEvaluatorVisitor;
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begin
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// Helper to encapsulate the Bind -> CreateScope -> Evaluate pattern.
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binder := TAstBinder.Create(FGlobalScope);
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boundNode := binder.Execute(ANode, descriptor);
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runtimeScope := descriptor.CreateScope(FGlobalScope);
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visitor := TEvaluatorVisitor.Create(runtimeScope);
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Result := visitor.Execute(boundNode);
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end;
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procedure TInterpreterScopeTests.Setup;
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begin
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FGlobalScope := TAst.CreateScope(nil);
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end;
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procedure TInterpreterScopeTests.TearDown;
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begin
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FGlobalScope := nil;
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end;
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procedure TInterpreterScopeTests.Test_DeeplyNestedLambda_ModifiesUpvalue;
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var
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mainBlock: IAstNode;
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resultValue: TDataValue;
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begin
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// This is our original, simple test case with three nested lambdas.
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mainBlock :=
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TAst.Block(
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[
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TAst.VarDecl(
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TAst.Identifier('outer'),
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TAst.LambdaExpr(
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[],
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TAst.Block(
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[
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TAst.VarDecl(TAst.Identifier('x'), TAst.Constant(TScalar.FromInt64(10))),
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TAst.VarDecl(
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TAst.Identifier('inner'),
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TAst.LambdaExpr(
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[],
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TAst.Block(
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[
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TAst.VarDecl(
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TAst.Identifier('innermost'),
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TAst.LambdaExpr(
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[],
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TAst.Assign(
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TAst.Identifier('x'),
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TAst.BinaryExpr(
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TAst.Identifier('x'),
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TScalar.TBinaryOp.Add,
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TAst.Constant(TScalar.FromInt64(5))
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)
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)
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)
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),
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TAst.FunctionCall(TAst.Identifier('innermost'), [])
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]
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)
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)
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),
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TAst.FunctionCall(TAst.Identifier('inner'), []),
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TAst.Identifier('x')
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]
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)
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)
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),
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TAst.VarDecl(TAst.Identifier('finalResult'), TAst.FunctionCall(TAst.Identifier('outer'), []))
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]
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);
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resultValue := Execute(mainBlock);
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Assert.AreEqual<Int64>(15, resultValue.AsScalar.Value.AsInt64, 'The final result should be 15.');
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end;
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procedure TInterpreterScopeTests.Test_SeparateClosures_ShareSameUpvalue;
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var
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mainBlock: IAstNode;
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resultValue: TDataValue;
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begin
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// This is our more complex "modifier/reader" test case.
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mainBlock :=
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TAst.Block(
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[
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TAst.VarDecl(TAst.Identifier('a'), TAst.Constant(TScalar.FromInt64(10))),
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TAst.VarDecl(
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TAst.Identifier('modifier'),
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TAst.LambdaExpr(
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[], // Outer modifier shell
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TAst.LambdaExpr(
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[], // Inner closure that is returned
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TAst.Assign(
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TAst.Identifier('a'),
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TAst.BinaryExpr(TAst.Identifier('a'), TScalar.TBinaryOp.Add, TAst.Constant(TScalar.FromInt64(5)))
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)
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)
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)
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),
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TAst.VarDecl(TAst.Identifier('reader'), TAst.LambdaExpr([], TAst.Identifier('a'))),
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TAst.VarDecl(TAst.Identifier('innermost_closure'), TAst.FunctionCall(TAst.Identifier('modifier'), [])),
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TAst.FunctionCall(TAst.Identifier('innermost_closure'), []),
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TAst.FunctionCall(TAst.Identifier('reader'), [])
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]
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);
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resultValue := Execute(mainBlock);
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Assert.AreEqual<Int64>(15, resultValue.AsScalar.Value.AsInt64, 'The final result should be 15.');
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end;
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procedure TInterpreterScopeTests.Test_NestedLambda_CapturesParameter;
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var
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mainBlock: IAstNode;
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resultValue: TDataValue;
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begin
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// Tests if a nested lambda can correctly capture a PARAMETER of its parent lambda.
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mainBlock :=
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TAst.Block(
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[
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TAst.VarDecl(
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TAst.Identifier('factory'),
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TAst.LambdaExpr(
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[TAst.Identifier('p')], // Parameter 'p'
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TAst.LambdaExpr(
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[], // Returned lambda captures 'p'
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TAst.BinaryExpr(TAst.Identifier('p'), TScalar.TBinaryOp.Multiply, TAst.Constant(TScalar.FromInt64(2)))
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)
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)
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),
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TAst.VarDecl(
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TAst.Identifier('multiplier'),
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TAst.FunctionCall(TAst.Identifier('factory'), [TAst.Constant(TScalar.FromInt64(21))])
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),
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TAst.FunctionCall(TAst.Identifier('multiplier'), [])
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]
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);
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resultValue := Execute(mainBlock);
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Assert.AreEqual<Int64>(42, resultValue.AsScalar.Value.AsInt64, 'The result of 21 * 2 should be 42.');
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end;
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procedure TInterpreterScopeTests.Test_VariableShadowing_DoesNotAffectUpvalue;
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var
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mainBlock: IAstNode;
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resultValue: TDataValue;
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begin
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// Tests that a local variable 'x' correctly "shadows" a parent's variable 'x'.
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// The modification of the inner 'x' must not affect the outer 'x'.
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mainBlock :=
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TAst.Block(
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[
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TAst.VarDecl(TAst.Identifier('x'), TAst.Constant(TScalar.FromInt64(10))),
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TAst.FunctionCall(
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TAst.LambdaExpr(
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[],
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TAst.Block(
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[
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// This 'x' should shadow the outer 'x'.
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TAst.VarDecl(TAst.Identifier('x'), TAst.Constant(TScalar.FromInt64(50))),
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TAst.Assign(TAst.Identifier('x'), TAst.Constant(TScalar.FromInt64(99)))
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]
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)
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),
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[]
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),
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// This final expression should return the value of the original, outer 'x'.
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TAst.Identifier('x')
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]
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);
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resultValue := Execute(mainBlock);
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Assert.AreEqual<Int64>(10, resultValue.AsScalar.Value.AsInt64, 'The outer "x" should remain unchanged.');
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end;
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procedure TInterpreterScopeTests.Test_CaptureFromGlobalScope;
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var
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mainBlock: IAstNode;
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resultValue: TDataValue;
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begin
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// Defines a variable in the global scope and ensures a simple script can access it.
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FGlobalScope.Define('g', TScalar.FromInt64(99));
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mainBlock := TAst.BinaryExpr(TAst.Identifier('g'), TScalar.TBinaryOp.Add, TAst.Constant(TScalar.FromInt64(1)));
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resultValue := Execute(mainBlock);
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Assert.AreEqual<Int64>(100, resultValue.AsScalar.Value.AsInt64, 'Should be able to access variables from the parent scope.');
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end;
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procedure TInterpreterScopeTests.Test_ClosureCaptureWithParentScopeReallocation;
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var
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rootScope: IExecutionScope;
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parentScope: IExecutionScope;
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lambdaScope: IExecutionScope;
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addressOfX_from_lambda: TResolvedAddress;
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addressOfX_in_parent: TResolvedAddress;
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capturedCell: IValueCell;
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valueFromClosure: TDataValue;
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begin
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// 1. Setup scopes: root -> parent -> lambda
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rootScope := TScope.CreateScope(nil, nil, nil);
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parentScope := TScope.CreateScope(rootScope, nil, nil);
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lambdaScope := TScope.CreateScope(parentScope, nil, nil);
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// 2. Define a variable 'x' in the parent scope. It will be at slot 0.
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parentScope.Define('x', 10);
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addressOfX_in_parent := TResolvedAddress.Create(akLocalOrParent, 0, 0);
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Assert.AreEqual(Int64(10), parentScope[addressOfX_in_parent].AsScalar.Value.AsInt64);
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// 3. From the lambda's perspective, 'x' is one level up (ScopeDepth=1) at slot 0.
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addressOfX_from_lambda := TResolvedAddress.Create(akLocalOrParent, 1, 0);
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// 4. Capture 'x' into a value cell, simulating a closure.
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// This creates the buggy TValueRef that holds a direct reference to the parent's internal array.
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capturedCell := lambdaScope.Capture(addressOfX_from_lambda);
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Assert.AreEqual(Int64(10), capturedCell.Value.AsScalar.Value.AsInt64, 'Initial captured value should be correct');
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// 5. Trigger the bug: Define another variable in the parent scope.
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// This forces a SetLength on the internal FValues array, which may cause a reallocation.
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parentScope.Define('y', 20);
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// 6. Update the original variable 'x' in the parent scope to a new value.
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parentScope[addressOfX_in_parent] := 99;
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Assert.AreEqual(Int64(99), parentScope[addressOfX_in_parent].AsScalar.Value.AsInt64, 'Value in parent scope should be updated');
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// 7. Read the value from the captured cell again.
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// The test will fail here. The captured cell still points to the old, orphaned memory block
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// where the value of x is still 10, not the new value 99.
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valueFromClosure := capturedCell.Value;
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Assert.AreEqual(
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Int64(99),
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valueFromClosure.AsScalar.Value.AsInt64,
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'The captured cell must reflect changes in the parent scope after reallocation'
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);
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end;
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end.
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