Refactoring Execute() method

Returning Engine to chain with other calls. Use
GetCompletionValue() explicitly if the last evaluated
value needs to be returned.

Jint.Tests/Runtime/EngineTests.cs

@@ -45,7 +45,7 @@ namespace Jint.Tests.Runtime
         public void ShouldInterpretLiterals(object expected, string source)
         {
             var engine = new Engine();
-            var result = engine.Execute(source).ToObject();
+            var result = engine.Execute(source).GetCompletionValue().ToObject();
 
             Assert.Equal(expected, result);
         }
@@ -73,7 +73,7 @@ namespace Jint.Tests.Runtime
         public void ShouldInterpretBinaryExpression(object expected, string source)
         {
             var engine = new Engine();
-            var result = engine.Execute(source).ToObject();
+            var result = engine.Execute(source).GetCompletionValue().ToObject();
 
             Assert.Equal(expected, result);
         }
@@ -527,7 +527,7 @@ namespace Jint.Tests.Runtime
         public void OperatorsPrecedence(object expected, string source)
         {
             var engine = new Engine();
-            var result = engine.Execute(source).ToObject();
+            var result = engine.Execute(source).GetCompletionValue().ToObject();
 
             Assert.Equal(expected, result);
         }
@@ -553,7 +553,7 @@ namespace Jint.Tests.Runtime
         public void ShouldEvaluateParseInt(object expected, string source)
         {
             var engine = new Engine();
-            var result = engine.Execute(source).ToObject();
+            var result = engine.Execute(source).GetCompletionValue().ToObject();
 
             Assert.Equal(expected, result);
         }

Jint.Tests/Runtime/InteropTests.cs

@@ -304,7 +304,7 @@ namespace Jint.Tests.Runtime
                 .SetValue("values", new[] { 1, 2, 3, 4, 5, 6 })
                 .Execute("values.filter(function(x){ return x % 2 == 0; })");
 
-            var parts = result.ToObject();
+            var parts = result.GetCompletionValue().ToObject();
 
             Assert.True(parts.GetType().IsArray);
             Assert.Equal(3, ((object[])parts).Length);
@@ -320,7 +320,7 @@ namespace Jint.Tests.Runtime
                 .SetValue("values", new List<object> { 1, 2, 3, 4, 5, 6 })
                 .Execute("values.filter(function(x){ return x % 2 == 0; })");
 
-            var parts = result.ToObject();
+            var parts = result.GetCompletionValue().ToObject();
 
             Assert.True(parts.GetType().IsArray);
             Assert.Equal(3, ((object[])parts).Length);
@@ -333,7 +333,7 @@ namespace Jint.Tests.Runtime
         public void ShouldConvertArrayInstanceToArray()
         {
             var result = _engine.Execute("'[email protected]'.split('@');");
-            var parts = result.ToObject();
+            var parts = result.GetCompletionValue().ToObject();
             
             Assert.True(parts.GetType().IsArray);
             Assert.Equal(2, ((object[])parts).Length);
@@ -345,7 +345,7 @@ namespace Jint.Tests.Runtime
         public void ShouldConvertBooleanInstanceToBool()
         {
             var result = _engine.Execute("new Boolean(true)");
-            var value = result.ToObject();
+            var value = result.GetCompletionValue().ToObject();
 
             Assert.Equal(typeof(bool), value.GetType());
             Assert.Equal(true, value);
@@ -355,7 +355,7 @@ namespace Jint.Tests.Runtime
         public void ShouldConvertDateInstanceToDateTime()
         {
             var result = _engine.Execute("new Date(0)");
-            var value = result.ToObject();
+            var value = result.GetCompletionValue().ToObject();
 
             Assert.Equal(typeof(DateTime), value.GetType());
             Assert.Equal(new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc), value);
@@ -365,7 +365,7 @@ namespace Jint.Tests.Runtime
         public void ShouldConvertNumberInstanceToDouble()
         {
             var result = _engine.Execute("new Number(10)");
-            var value = result.ToObject();
+            var value = result.GetCompletionValue().ToObject();
 
             Assert.Equal(typeof(double), value.GetType());
             Assert.Equal(10d, value);
@@ -375,7 +375,7 @@ namespace Jint.Tests.Runtime
         public void ShouldConvertStringInstanceToString()
         {
             var result = _engine.Execute("new String('foo')");
-            var value = result.ToObject();
+            var value = result.GetCompletionValue().ToObject();
 
             Assert.Equal(typeof(string), value.GetType());
             Assert.Equal("foo", value);

Jint.Tests/Runtime/SamplesTests.cs

@@ -30,6 +30,7 @@ namespace Jint.Tests.Runtime
             var square = new Engine()
                 .SetValue("x", 3)
                 .Execute("x * x")
+                .GetCompletionValue()
                 .ToObject();
 
             Assert.Equal(9d, square);

Jint/Engine.cs

@@ -30,8 +30,9 @@ namespace Jint
         private readonly ExpressionInterpreter _expressions;
         private readonly StatementInterpreter _statements;
         private readonly Stack<ExecutionContext> _executionContexts;
+        private JsValue _completionValue = JsValue.Undefined;
         private int _statementsCount;
-
+        
         public Engine() : this(null)
         {
         }
@@ -202,13 +203,13 @@ namespace Jint
             _statementsCount = 0;
         }
 
-        public JsValue Execute(string source)
+        public Engine Execute(string source)
         {
             var parser = new JavaScriptParser();
             return Execute(parser.Parse(source));
         }
 
-        public JsValue Execute(Program program)
+        public Engine Execute(Program program)
         {
             ResetStatementsCount();
 
@@ -222,8 +223,18 @@ namespace Jint
                     throw new JavaScriptException(result.GetValueOrDefault());
                 }
 
-                return GetValue(result.Value);
+                _completionValue = result.GetValueOrDefault();
             }
+
+            return this;
+        }
+
+        /// <summary>
+        /// Gets the last evaluated statement completion value
+        /// </summary>
+        public JsValue GetCompletionValue()
+        {
+            return _completionValue;
         }
 
         public Completion ExecuteStatement(Statement statement)