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Binder refactoring - extracted type checking

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This commit is contained in:
Michael Schimmel
2025-11-01 14:04:45 +01:00
parent 4687ecb9ca
commit 6826b75c19
6 changed files with 671 additions and 394 deletions
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Src/AST/Myc.Ast.TypeChecker.pas
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unit Myc.Ast.TypeChecker;
interface
uses
System.SysUtils,
System.Classes,
System.Generics.Collections,
Myc.Data.Scalar,
Myc.Data.Value,
Myc.Ast.Nodes,
Myc.Ast.Visitor,
Myc.Ast.Scope,
Myc.Ast.Types,
Myc.Ast,
Myc.Ast.Binding.Nodes;
type
IAstTypeChecker = interface(IAstVisitor)
function Execute(const RootNode: IAstNode; const ADecriptor: IScopeDescriptor): IAstNode;
end;
// This transformer runs *after* the TAstBinder.
// It takes the "Bound AST" (which has addresses but mostly TTypes.Unknown)
// and traverses it bottom-up to infer and check all static types.
// It modifies the node.StaticType property and updates the IScopeDescriptor.
TTypeChecker = class(TAstTransformer, IAstTypeChecker)
private
FCurrentDescriptor: IScopeDescriptor;
function SetType(const NodeData: TDataValue; const AType: IStaticType): TDataValue; overload;
protected
// Override all visit methods to perform type checking
function VisitIdentifier(const Node: IIdentifierNode): TDataValue; override;
function VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue; override;
function VisitAssignment(const Node: IAssignmentNode): TDataValue; override;
function VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue; override;
function VisitFunctionCall(const Node: IFunctionCallNode): TDataValue; override;
function VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue; override;
function VisitIfExpression(const Node: IIfExpressionNode): TDataValue; override;
function VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue; override;
function VisitBinaryExpression(const Node: IBinaryExpressionNode): TDataValue; override;
function VisitUnaryExpression(const Node: IUnaryExpressionNode): TDataValue; override;
function VisitMemberAccess(const Node: IMemberAccessNode): TDataValue; override;
function VisitIndexer(const Node: IIndexerNode): TDataValue; override;
function VisitRecordLiteral(const Node: IRecordLiteralNode): TDataValue; override;
function VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue; override;
function VisitAddSeriesItem(const Node: IAddSeriesItemNode): TDataValue; override;
function VisitSeriesLength(const Node: ISeriesLengthNode): TDataValue; override;
function VisitRecurNode(const Node: IRecurNode): TDataValue; override;
// Base cases (types are already known from binder)
function VisitConstant(const Node: IConstantNode): TDataValue; override;
function VisitKeyword(const Node: IKeywordNode): TDataValue; override;
// Compile-time nodes (should not be present)
function VisitMacroExpansionNode(const Node: IMacroExpansionNode): TDataValue; override;
function VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue; override;
public
constructor Create(const ADescriptor: IScopeDescriptor);
function Execute(const RootNode: IAstNode; const ADescriptor: IScopeDescriptor): IAstNode;
class function CheckTypes(const RootNode: IAstNode; const ADescriptor: IScopeDescriptor): IAstNode; static;
end;
implementation
uses
System.Generics.Defaults,
Myc.Data.Keyword;
{ TTypeChecker }
constructor TTypeChecker.Create(const ADescriptor: IScopeDescriptor);
begin
inherited Create;
Assert(Assigned(ADescriptor));
FCurrentDescriptor := ADescriptor;
end;
class function TTypeChecker.CheckTypes(const RootNode: IAstNode; const ADescriptor: IScopeDescriptor): IAstNode;
begin
var checker := TTypeChecker.Create(ADescriptor) as IAstTypeChecker;
Result := checker.Execute(RootNode, ADescriptor);
end;
function TTypeChecker.Execute(const RootNode: IAstNode; const ADescriptor: IScopeDescriptor): IAstNode;
begin
FCurrentDescriptor := ADescriptor;
var transformedValue := Accept(RootNode);
if transformedValue.IsVoid then
Result := TAst.Block([])
else
Result := transformedValue.AsIntf<IAstNode>;
(Result as TAstNode).StaticType := (Result as TAstNode).StaticType;
end;
function TTypeChecker.SetType(const NodeData: TDataValue; const AType: IStaticType): TDataValue;
begin
if (not NodeData.IsVoid) and (NodeData.Kind = vkInterface) then
(NodeData.AsIntf<IAstNode> as TAstNode).StaticType := AType;
Result := NodeData;
end;
function TTypeChecker.VisitConstant(const Node: IConstantNode): TDataValue;
begin
// Type was set by Binder, just propagate it up.
Result := TDataValue.FromIntf<IConstantNode>(Node);
end;
function TTypeChecker.VisitKeyword(const Node: IKeywordNode): TDataValue;
begin
// Type was set by Binder, just propagate it up.
Result := TDataValue.FromIntf<IKeywordNode>(Node);
end;
function TTypeChecker.VisitIdentifier(const Node: IIdentifierNode): TDataValue;
begin
// Type was set by Binder (read from scope), just propagate it up.
Result := TDataValue.FromIntf<IIdentifierNode>(Node);
end;
function TTypeChecker.VisitRecurNode(const Node: IRecurNode): TDataValue;
begin
// Type was set by Binder (TTypes.Void), just propagate it up.
Result := TDataValue.FromIntf<IRecurNode>(Node);
end;
function TTypeChecker.VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue;
begin
raise Exception.Create('TTypeChecker: MacroDefinition node encountered.');
end;
function TTypeChecker.VisitMacroExpansionNode(const Node: IMacroExpansionNode): TDataValue;
begin
raise Exception.Create('TTypeChecker: MacroExpansionNode node encountered.');
end;
function TTypeChecker.VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue;
var
initNode: IAstNode;
initType: IStaticType;
boundIdent: TBoundIdentifierNode;
adr: TResolvedAddress;
begin
// 1. Visit the initializer (if it exists) to get its (now-inferred) type.
if Assigned(Node.Initializer) then
begin
initNode := Accept(Node.Initializer).AsIntf<IAstNode>;
initType := (initNode as TAstNode).StaticType;
end
else
initType := TTypes.Void;
// 2. Get the address from the bound identifier.
boundIdent := (Node.Identifier as TBoundIdentifierNode);
adr := boundIdent.Address;
// 3. Update the type in the scope descriptor (which was set to Unknown by the binder).
FCurrentDescriptor.UpdateType(adr.SlotIndex, initType);
// 4. Update the static types of the nodes themselves.
(boundIdent as TAstNode).StaticType := initType;
Result := SetType(TDataValue.FromIntf(Node), initType);
end;
function TTypeChecker.VisitAssignment(const Node: IAssignmentNode): TDataValue;
var
boundIdentifier, boundValue: IAstNode;
targetType, sourceType: IStaticType;
begin
boundIdentifier := Accept(Node.Identifier).AsIntf<IAstNode>;
boundValue := Accept(Node.Value).AsIntf<IAstNode>;
targetType := (boundIdentifier as TAstNode).StaticType;
sourceType := (boundValue as TAstNode).StaticType;
if not TTypeRules.CanAssign(targetType, sourceType) then
raise ETypeException.CreateFmt('Cannot assign type %s to %s', [sourceType.ToString, targetType.ToString]);
Result := SetType(TDataValue.FromIntf<IAssignmentNode>(Node), targetType);
end;
function TTypeChecker.VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue;
var
boundNode: TBoundLambdaExpressionNode;
boundBody: IAstNode;
bodyType, methodType: IStaticType;
paramTypes: TArray<IStaticType>;
i: Integer;
begin
boundNode := (Node as TBoundLambdaExpressionNode);
// 1. Enter the lambda's scope
FCurrentDescriptor := boundNode.ScopeDescriptor;
try
// 2. Set parameter types (currently Unknown, but required for signature)
SetLength(paramTypes, Length(boundNode.Parameters));
for i := 0 to High(boundNode.Parameters) do
paramTypes[i] := (boundNode.Parameters[i] as TAstNode).StaticType; // Propagates Unknown
// 3. Visit the body to infer its return type
boundBody := Accept(boundNode.Body).AsIntf<IAstNode>;
bodyType := (boundBody as TAstNode).StaticType;
// 4. Create the final method type
methodType := TTypes.CreateMethod(paramTypes, bodyType);
// 5. Update the type for <self> (Slot 0) in the descriptor
FCurrentDescriptor.UpdateType(0, methodType);
finally
// 6. Restore parent descriptor
FCurrentDescriptor := FCurrentDescriptor.Parent;
end;
// 7. Set the type of the lambda node itself
Result := SetType(TDataValue.FromIntf<ILambdaExpressionNode>(boundNode), methodType);
end;
function TTypeChecker.VisitFunctionCall(const Node: IFunctionCallNode): TDataValue;
var
callee: IAstNode;
args: TArray<IAstNode>;
calleeType, retType: IStaticType;
i: Integer;
begin
// 1. Visit children first (bottom-up)
callee := Accept(Node.Callee).AsIntf<IAstNode>;
args := AcceptNodes<IAstNode>(Node.Arguments);
// 2. Get callee type (now inferred)
calleeType := (callee as TAstNode).StaticType;
retType := TTypes.Unknown; // Default if not a method
// 3. Perform type checking
if calleeType.Kind = TStaticTypeKind.stMethod then
begin
var signature := calleeType.Signature;
if Length(args) <> Length(signature.ParamTypes) then
raise ETypeException.CreateFmt('Function expects %d arguments, but got %d', [Length(signature.ParamTypes), Length(args)]);
retType := signature.ReturnType;
// Check argument types
for i := 0 to High(args) do
begin
var argType := (args[i] as TAstNode).StaticType;
var paramType := signature.ParamTypes[i];
if not TTypeRules.CanAssign(paramType, argType) then
raise ETypeException
.CreateFmt('Cannot assign argument %d (type %s) to parameter (type %s)', [i, argType.ToString, paramType.ToString]);
end;
end
else if calleeType.Kind <> TStaticTypeKind.stUnknown then
raise ETypeException.CreateFmt('Cannot invoke type %s as a function.', [calleeType.ToString]);
// 4. Set the type for this call node
Result := SetType(TDataValue.FromIntf<IFunctionCallNode>(Node), retType);
end;
function TTypeChecker.VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue;
var
blockType: IStaticType;
exprs: TArray<IAstNode>;
begin
exprs := AcceptNodes<IAstNode>(Node.Expressions);
if Length(exprs) > 0 then
blockType := (exprs[High(exprs)] as TAstNode).StaticType
else
blockType := TTypes.Void;
Result := SetType(TDataValue.FromIntf<IBlockExpressionNode>(Node), blockType);
end;
function TTypeChecker.VisitIfExpression(const Node: IIfExpressionNode): TDataValue;
var
condition, thenBranch, elseBranch: IAstNode;
conditionType, thenType, elseType, resultType: IStaticType;
begin
condition := Accept(Node.Condition).AsIntf<IAstNode>;
thenBranch := Accept(Node.ThenBranch).AsIntf<IAstNode>;
elseBranch := Accept(Node.ElseBranch).AsIntf<IAstNode>; // Accept(nil) returns void
conditionType := (condition as TAstNode).StaticType;
if (conditionType.Kind <> stUnknown) and not TTypeRules.CanAssign(TTypes.Ordinal, conditionType) then
raise ETypeException.CreateFmt('If condition must be Ordinal, but got %s', [conditionType.ToString]);
thenType := (thenBranch as TAstNode).StaticType;
elseType :=
if elseBranch <> nil then (elseBranch as TAstNode).StaticType
else TTypes.Void;
resultType := TTypeRules.Promote(thenType, elseType);
Result := SetType(TDataValue.FromIntf<IIfExpressionNode>(Node), resultType);
end;
function TTypeChecker.VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue;
var
condition, thenBranch, elseBranch: IAstNode;
conditionType, thenType, elseType, resultType: IStaticType;
begin
condition := Accept(Node.Condition).AsIntf<IAstNode>;
thenBranch := Accept(Node.ThenBranch).AsIntf<IAstNode>;
elseBranch := Accept(Node.ElseBranch).AsIntf<IAstNode>;
conditionType := (condition as TAstNode).StaticType;
if (conditionType.Kind <> stUnknown) and not TTypeRules.CanAssign(TTypes.Ordinal, conditionType) then
raise ETypeException.CreateFmt('Ternary condition must be Ordinal, but got %s', [conditionType.ToString]);
thenType := (thenBranch as TAstNode).StaticType;
elseType := (elseBranch as TAstNode).StaticType;
resultType := TTypeRules.Promote(thenType, elseType);
Result := SetType(TDataValue.FromIntf<ITernaryExpressionNode>(Node), resultType);
end;
function TTypeChecker.VisitBinaryExpression(const Node: IBinaryExpressionNode): TDataValue;
var
left, right: IAstNode;
leftType, rightType, resultType: IStaticType;
begin
left := Accept(Node.Left).AsIntf<IAstNode>;
right := Accept(Node.Right).AsIntf<IAstNode>;
leftType := (left as TAstNode).StaticType;
rightType := (right as TAstNode).StaticType;
resultType := TTypeRules.ResolveBinaryOp(Node.Operator, leftType, rightType);
Result := SetType(TDataValue.FromIntf<IBinaryExpressionNode>(Node), resultType);
end;
function TTypeChecker.VisitUnaryExpression(const Node: IUnaryExpressionNode): TDataValue;
var
right: IAstNode;
rightType, resultType: IStaticType;
begin
right := Accept(Node.Right).AsIntf<IAstNode>;
rightType := (right as TAstNode).StaticType;
resultType := TTypeRules.ResolveUnaryOp(Node.Operator, rightType);
Result := SetType(TDataValue.FromIntf<IUnaryExpressionNode>(Node), resultType);
end;
function TTypeChecker.VisitMemberAccess(const Node: IMemberAccessNode): TDataValue;
var
baseNode: IAstNode;
baseType, elemType: IStaticType;
fieldIndex: Integer;
begin
baseNode := Accept(Node.Base).AsIntf<IAstNode>;
baseType := (baseNode as TAstNode).StaticType;
elemType := TTypes.Unknown;
if (baseType.Kind <> TStaticTypeKind.stUnknown) then
begin
if (baseType.Kind = TStaticTypeKind.stRecord) or (baseType.Kind = TStaticTypeKind.stRecordSeries) then
begin
fieldIndex := baseType.Definition.IndexOf(Node.Member.Value);
if fieldIndex < 0 then
raise ETypeException.CreateFmt('Member "%s" not found in type %s', [Node.Member.Value.Name, baseType.ToString]);
var fieldType := TTypes.FromScalarKind(baseType.Definition.Fields[fieldIndex].Value);
if baseType.Kind = TStaticTypeKind.stRecord then
elemType := fieldType
else // stRecordSeries
elemType := TTypes.CreateSeries(fieldType);
end
else if (baseType.Kind = TStaticTypeKind.stGenericRecord) then
begin
var genDef := baseType.GenericDefinition;
fieldIndex := genDef.IndexOf(Node.Member.Value);
if fieldIndex < 0 then
raise ETypeException.CreateFmt('Member "%s" not found in type %s', [Node.Member.Value.Name, baseType.ToString]);
elemType := genDef.Fields[fieldIndex].Value;
end
else
begin
raise ETypeException.CreateFmt('Member access requires a record type, but got %s', [baseType.ToString]);
end;
end;
Result := SetType(TDataValue.FromIntf<IMemberAccessNode>(Node), elemType);
end;
function TTypeChecker.VisitIndexer(const Node: IIndexerNode): TDataValue;
var
baseNode, indexNode: IAstNode;
baseType, indexType, elemType: IStaticType;
begin
baseNode := Accept(Node.Base).AsIntf<IAstNode>;
indexNode := Accept(Node.Index).AsIntf<IAstNode>;
baseType := (baseNode as TAstNode).StaticType;
indexType := (indexNode as TAstNode).StaticType;
elemType := TTypes.Unknown;
if (baseType.Kind <> TStaticTypeKind.stUnknown) then
begin
if (baseType.Kind <> TStaticTypeKind.stSeries) and (baseType.Kind <> TStaticTypeKind.stRecordSeries) then
raise ETypeException.CreateFmt('Indexer `[]` can only be applied to series types, but got %s', [baseType.ToString]);
if (indexType.Kind <> stUnknown) and not TTypeRules.CanAssign(TTypes.Ordinal, indexType) then
raise ETypeException.CreateFmt('Indexer `[]` requires an Ordinal index, but got %s', [indexType.ToString]);
if baseType.Kind = TStaticTypeKind.stSeries then
elemType := baseType.ElementType
else // stRecordSeries
elemType := TTypes.CreateRecord(baseType.Definition);
end;
Result := SetType(TDataValue.FromIntf<IIndexerNode>(Node), elemType);
end;
function TTypeChecker.VisitRecordLiteral(const Node: IRecordLiteralNode): TDataValue;
var
i: Integer;
boundFields: TArray<TRecordFieldLiteral>;
scalarDefFields: TArray<TScalarRecordField>;
def: IScalarRecordDefinition;
staticType: IStaticType;
valNode: IAstNode;
valType: IStaticType;
scalarKind: TScalar.TKind;
allScalar: Boolean;
begin
SetLength(boundFields, Length(Node.Fields));
SetLength(scalarDefFields, Length(Node.Fields));
allScalar := True;
// 1. Visit all child nodes first to infer their types
for i := 0 to High(Node.Fields) do
begin
valNode := Accept(Node.Fields[i].Value).AsIntf<IAstNode>;
valType := (valNode as TAstNode).StaticType;
boundFields[i] := TRecordFieldLiteral.Create(Node.Fields[i].Key, valNode);
// 2. Check if this field fits the scalar path
if (valType.Kind = stOrdinal) then
scalarKind := TScalar.TKind.Ordinal
else if (valType.Kind = stFloat) then
scalarKind := TScalar.TKind.Float
else if (valType.Kind = stKeyword) then
scalarKind := TScalar.TKind.Keyword
else
begin
allScalar := False;
scalarKind := TScalar.TKind.Ordinal; // Dummy
end;
if allScalar then
scalarDefFields[i] := TScalarRecordField.Create(Node.Fields[i].Key.Value, scalarKind);
end;
// 3. Create the appropriate record type (Scalar or Generic)
if allScalar then
begin
def := TScalarRecordRegistry.Intern(scalarDefFields);
staticType := TTypes.CreateRecord(def);
// We can re-use the TBoundRecordLiteralNode from the binder
(Node as TBoundRecordLiteralNode).Definition := def;
end
else
begin
var genDefFields: TArray<TPair<IKeyword, IStaticType>>;
SetLength(genDefFields, Length(boundFields));
for i := 0 to High(boundFields) do
genDefFields[i] := TPair<IKeyword, IStaticType>.Create(boundFields[i].Key.Value, (boundFields[i].Value as TAstNode).StaticType);
var genDef := TGenericRecordRegistry.Intern(genDefFields);
staticType := TTypes.CreateGenericRecord(genDef);
// Re-use the TBoundGenericRecordLiteralNode from the binder
(Node as TBoundGenericRecordLiteralNode).Definition := genDef;
end;
Result := SetType(TDataValue.FromIntf<IRecordLiteralNode>(Node), staticType);
end;
function TTypeChecker.VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue;
begin
// Type was set by Binder, just propagate it up.
Result := TDataValue.FromIntf<ICreateSeriesNode>(Node);
end;
function TTypeChecker.VisitAddSeriesItem(const Node: IAddSeriesItemNode): TDataValue;
var
seriesNode, valueNode, lookbackNode: IAstNode;
seriesType, valueType: IStaticType;
begin
seriesNode := Accept(Node.Series).AsIntf<IAstNode>;
valueNode := Accept(Node.Value).AsIntf<IAstNode>;
lookbackNode := Accept(Node.Lookback).AsIntf<IAstNode>;
seriesType := (seriesNode as TAstNode).StaticType;
valueType := (valueNode as TAstNode).StaticType;
if (seriesType.Kind <> stUnknown) then
begin
if (seriesType.Kind <> TStaticTypeKind.stSeries) then
raise ETypeException.CreateFmt('"add" requires a series as its first argument, but got %s', [seriesType.ToString]);
if not TTypeRules.CanAssign(seriesType.ElementType, valueType) then
raise ETypeException
.CreateFmt('Cannot add item of type %s to series of type %s', [valueType.ToString, seriesType.ElementType.ToString]);
end;
if (lookbackNode <> nil) then
begin
var lookbackType := (lookbackNode as TAstNode).StaticType;
if (lookbackType.Kind <> stUnknown) and not (lookbackType.Kind = TStaticTypeKind.stOrdinal) then
raise ETypeException.Create('Lookback parameter for "add" must be an ordinal value.');
end;
Result := SetType(TDataValue.FromIntf<IAddSeriesItemNode>(Node), TTypes.Void);
end;
function TTypeChecker.VisitSeriesLength(const Node: ISeriesLengthNode): TDataValue;
var
seriesNode: IAstNode;
seriesType: IStaticType;
begin
seriesNode := Accept(Node.Series).AsIntf<IAstNode>;
seriesType := (seriesNode as TAstNode).StaticType;
if (seriesType.Kind <> stUnknown)
and (seriesType.Kind <> TStaticTypeKind.stSeries)
and (seriesType.Kind <> TStaticTypeKind.stRecordSeries) then
raise ETypeException.CreateFmt('"length" requires a series, but got %s', [seriesType.ToString]);
Result := SetType(TDataValue.FromIntf<ISeriesLengthNode>(Node), TTypes.Ordinal);
end;
end.