diff --git a/PublicTypes/RScriptVariables.cs b/PublicTypes/RScriptVariables.cs
index bd4a110..3ce4cd7 100644
--- a/PublicTypes/RScriptVariables.cs
+++ b/PublicTypes/RScriptVariables.cs
@@ -25,15 +25,14 @@ namespace Convention.RScript
                     internalData = value;
                     return;
                 }
-                internalData = Convert.ChangeType(value, type);
+                if (type == typeof(object) || type == value.GetType())
+                    internalData = value;
+                else
+                    internalData = Convert.ChangeType(value, type);
             }
         }
         private object internalData;
 
-        public RScriptVariableEntry(object data) : this()
-        {
-            this.data = data;
-        }
         public RScriptVariableEntry(Type type, object data) : this()
         {
             this.type = type;
diff --git a/RScriptContext.cs b/RScriptContext.cs
index 22b41d2..c0fd6d0 100644
--- a/RScriptContext.cs
+++ b/RScriptContext.cs
@@ -169,6 +169,30 @@ namespace Convention.RScript
             }
         }
 
+        public class BuildInContext
+        {
+            private RScriptContext context;
+            public BuildInContext(RScriptContext context)
+            {
+                this.context = context;
+            }
+
+            public bool ExistVar(string name)
+            {
+                return context.Variables.ContainsKey(name);
+            }
+
+            public bool ExistNamespace(string name)
+            {
+                return context.NamespaceLabels.ContainsKey(name);
+            }
+
+            public bool ExistLabel(string name)
+            {
+                return context.Labels.ContainsKey(name);
+            }
+        }
+
         public RScriptContext(string[] expressions,
                               RScriptImportClass import = null,
                               RScriptVariables variables = null,
@@ -177,6 +201,7 @@ namespace Convention.RScript
         {
             this.Import = import ?? new();
             this.Variables = variables ?? new();
+            this.Variables.Add("context", new(typeof(object), new BuildInContext(this)));
             this.Sentences = (from item in expressions select ParseToSentence(item)).ToArray();
             if (matcher != null)
                 this.SentenceParser = matcher;
@@ -221,13 +246,26 @@ namespace Convention.RScript
             return result;
         }
 
-        public void Run(ExpressionParser parser)
+        private void BeforeRun(ExpressionParser parser)
         {
             CurrentLocalSpaceVariableNames.Clear();
             RuntimePointerStack.Clear();
             GotoPointerStack.Clear();
             CurrentLocalSpaceVariableNames.Clear();
             CurrentLocalSpaceVariableNames.Push(new());
+            foreach (var staticType in Import)
+            {
+                parser.context.Imports.AddType(staticType);
+            }
+            foreach (var (name,varObject) in Variables)
+            {
+                parser.context.Variables[name] = varObject.data;
+            }
+        }
+
+        public void Run(ExpressionParser parser)
+        {
+            BeforeRun(parser);
             for (CurrentRuntimePointer = 0; CurrentRuntimePointer < Sentences.Length; CurrentRuntimePointer++)
             {
                 RunNextStep(parser);
@@ -242,11 +280,7 @@ namespace Convention.RScript
 
         public IEnumerator RunAsync(ExpressionParser parser)
         {
-            CurrentLocalSpaceVariableNames.Clear();
-            RuntimePointerStack.Clear();
-            GotoPointerStack.Clear();
-            CurrentLocalSpaceVariableNames.Clear();
-            CurrentLocalSpaceVariableNames.Push(new());
+            BeforeRun(parser);
             for (CurrentRuntimePointer = 0; CurrentRuntimePointer < Sentences.Length; CurrentRuntimePointer++)
             {
                 var ret = RunNextStep(parser);
diff --git a/RScriptEngine.cs b/RScriptEngine.cs
index f3482be..3779c00 100644
--- a/RScriptEngine.cs
+++ b/RScriptEngine.cs
@@ -42,16 +42,16 @@ namespace Convention.RScript
                     else if (c == '/' && i + 1 < e)
                     {
                         // Skip single-line comment
-                        if (script[i + 1] == '/')
+                        if (line[i + 1] == '/')
                         {
-                            while (i < script.Length && script[i] != '\n')
+                            while (i < line.Length && line[i] != '\n')
                                 i++;
                         }
                         // Skip multi-line comment
-                        else if (script[i + 1] == '*')
+                        else if (line[i + 1] == '*')
                         {
                             i += 2;
-                            while (i + 1 < script.Length && !(script[i] == '*' && script[i + 1] == '/'))
+                            while (i + 1 < line.Length && !(line[i] == '*' && line[i + 1] == '/'))
                                 i++;
                             i++;
                         }
@@ -63,23 +63,24 @@ namespace Convention.RScript
                     else if (c == '#')
                     {
                         // Skip single-line comment
-                        while (i < script.Length && script[i] != '\n')
+                        while (i < line.Length && line[i] != '\n')
                             i++;
                     }
                     else if (c == '\"')
                     {
+                        builder.Append(c);
                         for (i++; i < e; i++)
                         {
-                            builder.Append(script[i]);
-                            if (script[i] == '\"')
+                            builder.Append(line[i]);
+                            if (line[i] == '\"')
                             {
                                 break;
                             }
-                            else if (script[i] == '\\')
+                            else if (line[i] == '\\')
                             {
                                 i++;
                                 if (i < e)
-                                    builder.Append(script[i]);
+                                    builder.Append(line[i]);
                                 else
                                     throw new RScriptCompileException("Invalid escape sequence in string literal", lineIndex, i);
                             }
@@ -90,14 +91,10 @@ namespace Convention.RScript
                         PushBuilder();
                         statements.Add(c.ToString());
                     }
-                    else if (string.Compare("namespace", 0, script, i, "namespace".Length) == 0)
+                    else if (string.Compare("namespace", 0, line, i, "namespace".Length) == 0)
                     {
-                        builder.Append("namespace");
-                        i += "namespace".Length;
-                        if (i >= e)
-                            throw new RScriptCompileException("Invalid namespace declaration", lineIndex, i);
-                        Regex regex = new(@"^\s*\([a-zA-Z_][a-zA-Z0-9_]*\)");
-                        var match = regex.Match(script, i);
+                        Regex regex = new(@"^\s*namespace\s*\([a-zA-Z_][a-zA-Z0-9_]*\)");
+                        var match = regex.Match(line);
                         if (match.Success)
                         {
                             builder.Append(match.Value);
@@ -129,8 +126,6 @@ namespace Convention.RScript
         {
             parser = new(new());
             context = new(SplitScript(script).ToArray(), import, variables);
-            foreach (var type in context.Import)
-                parser.context.Imports.AddType(type);
             context.Run(parser);
             return context.GetCurrentVariables();
         }
@@ -139,8 +134,6 @@ namespace Convention.RScript
         {
             parser = new(new());
             context = new(SplitScript(script).ToArray(), import, variables);
-            foreach (var type in context.Import)
-                parser.context.Imports.AddType(type);
             return context.RunAsync(parser);
         }
     }