Macro expander integrated in binder

Src/AST/Myc.Ast.Scope.pas

@@ -45,7 +45,7 @@ type
         property Parent: IExecutionScope read GetParent;
     end;
 
-    // Describes the layout of a scope: variable names and their slot indices.
+    // Describes the layout of a scope: variable names, their slot indices and macros.
     // This is generated by the binder and used to create TExecutionScope instances at runtime.
     IScopeDescriptor = interface
         {$region 'private'}
@@ -55,7 +55,9 @@ type
         {$endregion}
         function CreateScope(const AParent: IExecutionScope): IExecutionScope;
         function Define(const Name: string): Integer;
+        procedure DefineMacro(const Name: string; const Node: IMacroDefinitionNode);
         function FindSymbol(const Name: string): TResolvedAddress;
+        function FindMacro(const Name: string): IMacroDefinitionNode;
         property Parent: IScopeDescriptor read GetParent;
         property SlotCount: Integer read GetSlotCount;
         property Symbols: TDictionary<string, Integer> read GetSymbols;
@@ -77,7 +79,8 @@ implementation
 
 uses
     System.Generics.Defaults,
-    System.SyncObjs;
+    System.SyncObjs,
+    Myc.Ast;
 
 type
     TExecutionScope = class(TInterfacedObject, IExecutionScope)
@@ -132,6 +135,7 @@ type
     private
         FParent: IScopeDescriptor;
         FSymbols: TDictionary<string, Integer>;
+        FMacros: TDictionary<string, IMacroDefinitionNode>;
         function GetParent: IScopeDescriptor;
         function GetSlotCount: Integer;
         function GetSymbols: TDictionary<string, Integer>;
@@ -140,7 +144,9 @@ type
         destructor Destroy; override;
         class function CreateDescriptor(const Scope: IExecutionScope): IScopeDescriptor; static;
         function Define(const Name: string): Integer;
+        procedure DefineMacro(const Name: string; const Node: IMacroDefinitionNode);
         function FindSymbol(const Name: string): TResolvedAddress;
+        function FindMacro(const Name: string): IMacroDefinitionNode;
         function CreateScope(const Parent: IExecutionScope): IExecutionScope;
         procedure PopulateFromScope(Scope: TExecutionScope);
         property Symbols: TDictionary<string, Integer> read FSymbols;
@@ -447,16 +453,18 @@ begin
 end;
 
 { TScopeDescriptor }
-// ... (Implementation unchanged and correct) ...
+
 constructor TScopeDescriptor.Create(const AParent: IScopeDescriptor);
 begin
     inherited Create;
     FParent := AParent;
     FSymbols := TDictionary<string, Integer>.Create;
+    FMacros := TDictionary<string, IMacroDefinitionNode>.Create;
 end;
 
 destructor TScopeDescriptor.Destroy;
 begin
+    FMacros.Free;
     FSymbols.Free;
     inherited;
 end;
@@ -484,22 +492,42 @@ begin
     FSymbols.Add(Name, Result);
 end;
 
-function TScopeDescriptor.FindSymbol(const Name: string): TResolvedAddress;
+procedure TScopeDescriptor.DefineMacro(const Name: string; const Node: IMacroDefinitionNode);
+begin
+    FMacros.AddOrSetValue(Name, Node);
+end;
+
+function TScopeDescriptor.FindMacro(const Name: string): IMacroDefinitionNode;
 var
     currentDescriptor: TScopeDescriptor;
+begin
+    // Find a macro by searching up the parent scope chain.
+    Result := nil;
+    currentDescriptor := Self;
+    while Assigned(currentDescriptor) do
+    begin
+        if currentDescriptor.FMacros.TryGetValue(Name, Result) then
+            exit;
+        currentDescriptor := currentDescriptor.FParent as TScopeDescriptor;
+    end;
+end;
+
+function TScopeDescriptor.FindSymbol(const Name: string): TResolvedAddress;
+var
+    currentDescriptor: IScopeDescriptor;
 begin
     Result.Kind := akUnresolved;
     Result.ScopeDepth := 0;
     currentDescriptor := Self;
-    while currentDescriptor <> nil do
+    while Assigned(currentDescriptor) do
     begin
-        if currentDescriptor.FSymbols.TryGetValue(Name, Result.SlotIndex) then
+        if currentDescriptor.Symbols.TryGetValue(Name, Result.SlotIndex) then
         begin
             Result.Kind := akLocalOrParent;
             exit;
         end;
         inc(Result.ScopeDepth);
-        currentDescriptor := currentDescriptor.FParent as TScopeDescriptor;
+        currentDescriptor := currentDescriptor.Parent;
     end;
 end;
 
@@ -519,15 +547,31 @@ begin
 end;
 
 procedure TScopeDescriptor.PopulateFromScope(Scope: TExecutionScope);
+var
+    val: TDataValue;
 begin
+    // Recreate descriptor by iterating all defined symbols in the runtime scope.
     for var pair in Scope.NameToIndex do
     begin
         var name := Scope.NameStrings[pair.Key];
+        var slotIndex := pair.Value;
+
+        // Add to variable symbol table.
         if not FSymbols.ContainsKey(name) then
-            FSymbols.Add(name, pair.Value);
+            FSymbols.Add(name, slotIndex);
+
+        // Check if the symbol is also a macro and add it to the macro table.
+        val := Scope.FValues[slotIndex].Value;
+        if (val.Kind = vkInterface) and (val.AsIntf<IAstNode> is TMacroDefinitionNode) then
+        begin
+            if not FMacros.ContainsKey(name) then
+                FMacros.Add(name, val.AsIntf<IMacroDefinitionNode>);
+        end;
     end;
 end;
 
+{ TScope }
+
 class function TScope.CreateDescriptor(const Parent: IScopeDescriptor): IScopeDescriptor;
 begin
     Result := TScopeDescriptor.Create(Parent);