Way better handling of calling functions from CSHarp

Upsilon/BaseTypes/Number/NumberLong.cs

@@ -25,6 +25,8 @@ namespace Upsilon.BaseTypes.Number
 
         public static implicit operator long(NumberLong n)
         {
+            if (n == null)
+                return 0;
             return n.Value;
         }
     }

Upsilon/Binder/Binder.cs

@@ -38,7 +38,7 @@ namespace Upsilon.Binder
                 unboundFunctionStatement.Key.IsBound = true;
             }
             _unboundFunctions = new Dictionary<FunctionVariableSymbol, UnboundFunctionStatement>();
-            return new BoundScript(bound);
+            return new BoundScript((BoundBlockStatement) bound);
         }
 
         private BoundStatement BindStatement(StatementSyntax s)
@@ -173,8 +173,9 @@ namespace Upsilon.Binder
                     _scope.SetVariable(functionVariable);
                 }
 
-                _unboundFunctions[function].Block =
-                    (BoundBlockStatement) BindBlockStatement(_unboundFunctions[function].UnboundBlock);
+                var unboundFunctionStatement = _unboundFunctions[function];
+                unboundFunctionStatement.Block =
+                    (BoundBlockStatement) BindBlockStatement(unboundFunctionStatement.UnboundBlock);
                 _scope = _scope.ParentScope;
                 function.IsBound = true;
                 _unboundFunctions.Remove(function);
@@ -330,7 +331,8 @@ namespace Upsilon.Binder
                 var block = BindBlockStatement(e.Block);
                 _scope = _scope.ParentScope;
                 ((FunctionVariableSymbol) variable).IsBound = true;
-                return new BoundFunctionStatement(variable, parameters.ToImmutable(), (BoundBlockStatement) block);
+                var func = new BoundFunctionStatement(variable, parameters.ToImmutable(), (BoundBlockStatement) block);
+                return func;
             }
             else
             {

Upsilon/Binder/BoundStatements/BoundFunctionStatement.cs

@@ -6,7 +6,7 @@ namespace Upsilon.Binder
     {
         public VariableSymbol Identifier { get; }
         public ImmutableArray<VariableSymbol> Parameters { get; }
-        public BoundBlockStatement Block { get; }
+        public BoundBlockStatement Block { get; set; }
 
         public BoundFunctionStatement(VariableSymbol identifier, ImmutableArray<VariableSymbol> parameters,
             BoundBlockStatement block)

Upsilon/Binder/BoundStatements/BoundScript.cs

@@ -1,14 +1,16 @@
+using System.Collections.Generic;
+
 namespace Upsilon.Binder
 {
     public class BoundScript : BoundStatement
     {
-        public BoundScript(BoundStatement statement)
+        public BoundScript(BoundBlockStatement statement)
         {
             Statement = statement;
         }
 
         public override BoundKind Kind => BoundKind.BoundScript;
 
-        public BoundStatement Statement { get; }
+        public BoundBlockStatement Statement { get; }
     }
 }

Upsilon/Binder/BoundStatements/UnboundFunctionStatement.cs

@@ -3,21 +3,16 @@ using Upsilon.Parser;
 
 namespace Upsilon.Binder
 {
-    public class UnboundFunctionStatement : BoundStatement
+    public class UnboundFunctionStatement : BoundFunctionStatement
     {
         public UnboundFunctionStatement(VariableSymbol identifier, ImmutableArray<VariableSymbol> parameters,
-            BlockStatementSyntax unboundBlock)
+            BlockStatementSyntax unboundBlock) : base(identifier, parameters, null)
         {
-            Identifier = identifier;
-            Parameters = parameters;
             UnboundBlock = unboundBlock;
         }
 
         public override BoundKind Kind => BoundKind.BoundPromise;
 
-        public VariableSymbol                 Identifier { get; }
-        public ImmutableArray<VariableSymbol> Parameters { get; }
         public BlockStatementSyntax UnboundBlock { get; }
-        public BoundBlockStatement Block { get; set; }
     }
 }

Upsilon/Evaluator/Evaluator.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using Upsilon.BaseTypes;
 using Upsilon.BaseTypes.Number;
 using Upsilon.Binder;
+using Type = Upsilon.BaseTypes.Type;
 
 namespace Upsilon.Evaluator
 {
@@ -34,6 +35,18 @@ namespace Upsilon.Evaluator
             return _returnValue;
         }
 
+        public LuaType Evaluate(BoundScript e, string functionName)
+        {
+            Evaluate(e.Statement);
+            if (!Scope.TryGet(functionName, out var statement) || statement.Type != Type.Function)
+            {
+                throw new ArgumentException(($"Function '{functionName}' could not be found"));
+            }
+            var innerEvaluator = new Evaluator(_diagnostics, Scope);
+            var result = innerEvaluator.Evaluate(((LuaFunction)statement).Block);
+            return result;
+        }
+
         private LuaType Evaluate(BoundNode b)
         {
             switch (b.Kind)

Upsilon/Evaluator/Script.cs

@@ -12,6 +12,7 @@ namespace Upsilon.Evaluator
         private SourceText ScriptString { get; }
         private Evaluator Evaluator { get; }
         private readonly BlockStatementSyntax _parsed;
+        private BoundScript _bound;
         public Diagnostics Diagnostics { get; }
         private Binder.Binder Binder { get; }
         public EvaluationScope Scope { get; }
@@ -30,7 +31,7 @@ namespace Upsilon.Evaluator
 
         public BoundScript Bind()
         {
-            return Binder.BindScript(_parsed);
+            return _bound ?? (_bound = Binder.BindScript(_parsed));
         }
 
         public object Evaluate()
@@ -38,11 +39,21 @@ namespace Upsilon.Evaluator
             return Evaluator.Evaluate(Bind());
         }
 
+        public object EvaluateFunction(string functionName)
+        {
+            return Evaluator.Evaluate(Bind(), functionName);
+        }
+
         public T Evaluate<T>() where T : LuaType
         {
             return (T)Evaluator.Evaluate(Bind());
         }
 
+        public T EvaluateFunction<T>(string functionName) where T : LuaType
+        {
+            return (T)Evaluator.Evaluate(Bind(), functionName);
+        }
+
         public string PrettyPrintSyntaxTree()
         {
             return _parsed.Print();

UpsilonTests/FunctionTests.cs

@@ -151,5 +151,20 @@ a = 87
             Assert.Equal(60, (long)(NumberLong)result);
         }
 
+        [Fact]
+        public void ReturnFromCSharpCall()
+        {
+            const string input = @"
+function testFunc ()
+    return 100
+end
+";
+            var script = new Script(input);
+            Assert.Empty(script.Diagnostics.Messages);
+            var result = script.EvaluateFunction<NumberLong>("testFunc");
+            Assert.Empty(script.Diagnostics.Messages);
+            Assert.Equal(100, (long)result);
+        }
+
     }
 }