From 62ad100aeef31f3dd63698dbe37986fa3ab3b0bc Mon Sep 17 00:00:00 2001
From: Deukhoofd <Deukhoofd@gmail.com>
Date: Fri, 16 Nov 2018 14:11:27 +0100
Subject: [PATCH] More logical handling of return values

---
 Upsilon/Binder/Binder.cs       |  2 +-
 Upsilon/Evaluator/Evaluator.cs | 24 ++++++++++++++----------
 Ycicle/Program.cs              |  2 ++
 3 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/Upsilon/Binder/Binder.cs b/Upsilon/Binder/Binder.cs
index 6668987..8d7d7ac 100644
--- a/Upsilon/Binder/Binder.cs
+++ b/Upsilon/Binder/Binder.cs
@@ -181,7 +181,7 @@ namespace Upsilon.Binder
             }
 
             //TODO: validate parameters
-            return new BoundFunctionCallExpression((FunctionVariableSymbol) function, parameters.ToImmutable());
+            return new BoundFunctionCallExpression(function, parameters.ToImmutable());
         }
 
         private BoundExpression BindVariableExpression(VariableExpressionSyntax e)
diff --git a/Upsilon/Evaluator/Evaluator.cs b/Upsilon/Evaluator/Evaluator.cs
index 4b923f4..ad97b36 100644
--- a/Upsilon/Evaluator/Evaluator.cs
+++ b/Upsilon/Evaluator/Evaluator.cs
@@ -9,7 +9,8 @@ namespace Upsilon.Evaluator
     public class Evaluator
     {
         private readonly Diagnostics _diagnostics;
-        private LuaType _value;
+        private LuaType _lastValue;
+        private LuaType _returnValue;
         public EvaluationScope Scope { get; }
         private bool HasReturned { get; set; }
 
@@ -28,7 +29,9 @@ namespace Upsilon.Evaluator
         public LuaType Evaluate(BoundScript e)
         {
             Evaluate(e.Statement);
-            return _value;
+            if (_returnValue == null)
+                return _lastValue;
+            return _returnValue;
         }
 
         private LuaType Evaluate(BoundNode b)
@@ -43,7 +46,7 @@ namespace Upsilon.Evaluator
                 case BoundKind.BoundUnaryExpression:
                 case BoundKind.VariableExpression:
                 case BoundKind.BoundFunctionCallExpression:
-                    _value = EvaluateExpression((BoundExpression) b);
+                    _lastValue = EvaluateExpression((BoundExpression) b);
                     break;
                 case BoundKind.BoundAssignmentStatement:
                 case BoundKind.BoundExpressionStatement:
@@ -57,7 +60,7 @@ namespace Upsilon.Evaluator
                 default:
                     throw new ArgumentOutOfRangeException();
             }
-            return _value;
+            return _returnValue;
         }
 
         private void EvaluateStatement(BoundStatement e)
@@ -93,7 +96,7 @@ namespace Upsilon.Evaluator
 
         private void EvaluateExpressionStatement(BoundExpressionStatement e)
         {
-            _value = EvaluateExpression(e.Expression);
+            _lastValue = EvaluateExpression(e.Expression);
         }
 
         private LuaType EvaluateExpression(BoundExpression e)
@@ -165,7 +168,7 @@ namespace Upsilon.Evaluator
             {
                 Scope.SetGlobal(e.Variable, val);
             }
-            _value = val;
+            _lastValue = val;
         }
 
         private LuaType EvaluateVariableExpression(BoundVariableExpression e)
@@ -204,7 +207,7 @@ namespace Upsilon.Evaluator
                 innerEvaluator.EvaluateStatement(boundBlockStatement.ElseStatement.Block);
             }
             HasReturned = innerEvaluator.HasReturned;
-            _value = innerEvaluator._value;
+            _lastValue = innerEvaluator._lastValue;
         }
 
         private void EvaluateBoundFunctionStatement(BoundFunctionStatement boundFunctionStatement)
@@ -243,13 +246,14 @@ namespace Upsilon.Evaluator
                 var parameterValue = innerEvaluator.EvaluateExpression(boundFunctionCallExpression.Parameters[i]);
                 innerEvaluator.Scope.Set(parameterVariable, parameterValue);
             }
-            _value = innerEvaluator.Evaluate(function.Block);
-            return _value;
+            _lastValue = innerEvaluator.Evaluate(function.Block);
+            return _lastValue;
         }
 
         private void EvaluateReturnStatement(BoundReturnStatement b)
         {
-            _value = Evaluate(b.Expression);
+            _returnValue = EvaluateExpression(b.Expression);
+            _lastValue = _returnValue;
             HasReturned = true;
         }
 
diff --git a/Ycicle/Program.cs b/Ycicle/Program.cs
index 92c9704..b8e985b 100644
--- a/Ycicle/Program.cs
+++ b/Ycicle/Program.cs
@@ -51,6 +51,8 @@ namespace Ycicle
                 else
                 {
                     var evaluate = parsed.Evaluate();
+                    if (evaluate == null)
+                        continue;
                     if (parsed.Diagnostics.Messages.Count > 0)
                     {
                         Console.ForegroundColor = ConsoleColor.Red;