Ast environments

Src/AST/Myc.Ast.Scope.pas

@@ -49,7 +49,8 @@ type
         procedure SetValues(const Address: TResolvedAddress; const Value: TDataValue);
         {$endregion}
 
-        procedure Define(const Name: string; const Value: TDataValue);
+        // Defines a symbol and returns its runtime address
+        function Define(const Name: string; const Value: TDataValue): TResolvedAddress;
 
         // Defines a variable at a given address and stores it directly in a shared cell (boxing).
         procedure DefineBoxed(SlotIndex: Integer; const Value: TDataValue);
@@ -59,6 +60,8 @@ type
         function Capture(const Address: TResolvedAddress): IValueCell;
 
         function GetNameID(const Name: String): Integer;
+        // Resolves a name to an address by searching the runtime scope chain.
+        function Resolve(const Name: string): TResolvedAddress;
 
         function CreateDescriptor: IScopeDescriptor;
 
@@ -143,8 +146,9 @@ type
         destructor Destroy; override;
         procedure Clear;
         function GetNameID(const Name: String): Integer;
+        function Resolve(const Name: string): TResolvedAddress;
         function Dump: string;
-        procedure Define(const Name: string; const Value: TDataValue);
+        function Define(const Name: string; const Value: TDataValue): TResolvedAddress;
         procedure DefineBoxed(SlotIndex: Integer; const Value: TDataValue);
         function Capture(const Address: TResolvedAddress): IValueCell;
         function CreateDescriptor: IScopeDescriptor;
@@ -336,7 +340,7 @@ begin
     Result := TScopeDescriptor.CreateDescriptor(Self);
 end;
 
-procedure TExecutionScope.Define(const Name: string; const Value: TDataValue);
+function TExecutionScope.Define(const Name: string; const Value: TDataValue): TResolvedAddress;
 var
     id: Integer;
     index: Integer;
@@ -351,6 +355,11 @@ begin
     FValues[index].Value := Value;
     FValues[index].IsBoxed := False;
     FNameToIndex.Add(id, index);
+
+    // Return the address
+    Result.Kind := akLocalOrParent;
+    Result.ScopeDepth := 0;
+    Result.SlotIndex := index;
 end;
 
 procedure TExecutionScope.DefineBoxed(SlotIndex: Integer; const Value: TDataValue);
@@ -480,6 +489,42 @@ begin
     end;
 end;
 
+function TExecutionScope.Resolve(const Name: string): TResolvedAddress;
+var
+    nameID: Integer;
+    slotIndex: Integer;
+    currentScope: IExecutionScope;
+    depth: Integer;
+begin
+    currentScope := Self;
+    depth := 0;
+    // GetNameID is shared (or recreated) across the scope chain
+    nameID := GetNameID(Name);
+
+    while Assigned(currentScope) do
+    begin
+        // We must cast to the implementation class to access 'NameToIndex'
+        var execScopeImpl := (currentScope as TExecutionScope);
+
+        // Accessing .NameToIndex property ensures NeedNameToIndex is called
+        if execScopeImpl.NameToIndex.TryGetValue(nameID, slotIndex) then
+        begin
+            // Found in this scope
+            Result.Kind := akLocalOrParent;
+            Result.ScopeDepth := depth;
+            Result.SlotIndex := slotIndex;
+            exit;
+        end;
+
+        // Not found, go to parent
+        inc(depth);
+        currentScope := currentScope.Parent;
+    end;
+
+    // Not found in the entire chain
+    Result := Default(TResolvedAddress); // Kind = akUnresolved
+end;
+
 procedure TExecutionScope.SetValues(const Address: TResolvedAddress; const Value: TDataValue);
 var
     targetScope: TExecutionScope;