Sample SMA strategy

ASTPlayground/Myc.Ast.Visualizer.pas

@@ -76,6 +76,7 @@ type
             const Title, Details: string;
             const InPin, OutPin: String;
             IsExec: Boolean;
+            HasResult: Boolean;
             const ChildVisitorProc: TChildVisitorProc
         ): TAuraNode;
         function VisitOperatorNode(
@@ -181,7 +182,8 @@ implementation
 
 uses
     System.Math,
-    System.StrUtils;
+    System.StrUtils,
+    Myc.Data.Scalar;
 
 type
     // This visitor converts an AST expression subtree into a single string.
@@ -284,7 +286,7 @@ var
 begin
     sb := TStringBuilder.Create;
     try
-        sb.Append('(');
+        sb.Append(#$03BB + '(');
         if Length(Node.Parameters) > 0 then
         begin
             for i := 0 to High(Node.Parameters) do
@@ -677,6 +679,7 @@ begin
             '',
             '',
             true,
+            false,
             procedure(const Visitor: IAstVisitor)
             var
                 expression: IExpressionNode;
@@ -715,6 +718,7 @@ function TAstToAuraNodeVisitor.VisitContainerNode(
     const Title, Details: string;
     const InPin, OutPin: String;
     IsExec: Boolean;
+    HasResult: Boolean;
     const ChildVisitorProc: TChildVisitorProc
 ): TAuraNode;
 var
@@ -724,6 +728,7 @@ var
     maxRight: Single;
     maxBottom: Single;
     control: TControl;
+    childLastResult: TAuraNodeResult;
 begin
     const pinNodeHeight = cPinSize + cVerticalPadding;
 
@@ -764,6 +769,9 @@ begin
     childVisitor := TAstToAuraNodeVisitor.Create(FWorkspace, containerNode, childStartPos, FConnections, FCurrentExec.ToArray, FMode);
     ChildVisitorProc(childVisitor);
 
+    // Capture the result from the child visitor.
+    childLastResult := (childVisitor as TAstToAuraNodeVisitor).FLastResult;
+
     FCurrentExec.Clear;
     FCurrentExec.AddRange((childVisitor as TAstToAuraNodeVisitor).FCurrentExec);
 
@@ -781,7 +789,7 @@ begin
 
     // The width must be at least the title width, and large enough for children.
     containerNode.Width := Max(containerNode.Width, maxRight + FSpacing.X);
-    containerNode.Height := Max(containerNode.Height, maxBottom + FSpacing.Y + IfThen(OutPin <> '', pinNodeHeight, 0));
+    containerNode.Height := Max(containerNode.Height, maxBottom + FSpacing.Y);
 
     if OutPin <> '' then
     begin
@@ -789,8 +797,19 @@ begin
         exitNode.Parent := containerNode;
         exitNode.Height := pinNodeHeight;
         var exitPin := CreateEntry(exitNode);
+
+        // Create and connect a data pin if the container returns a value.
+        if HasResult and Assigned(childLastResult.OutputPin) then
+        begin
+            var dataResultPin := CreateInput(exitNode, 'Result');
+            FConnections.Add(TPinConnection.Create(childLastResult.OutputPin, dataResultPin));
+        end;
+
         FinalizeNodeLayout(exitNode);
 
+        // Enlarge for the exit node
+        containerNode.Height := Max(containerNode.Height, maxBottom + FSpacing.Y + exitNode.Height);
+
         exitNode.Position.Point := TPointF.Create(containerNode.Width - exitNode.Width, containerNode.Height - exitNode.Height);
 
         if not IsExec then
@@ -1022,11 +1041,12 @@ begin
     // Use the helper to create and populate the container node.
     lambdaNode :=
         VisitContainerNode(
-            'Lambda',
+            #$03BB,
             paramStr,
             'call',
             'return',
             false,
+            true,
             procedure(const Visitor: IAstVisitor) begin Node.Body.Accept(Visitor); end
         );