Move NRefactory.CSharp to separate assembly.

1 files changed, 1128 insertions, 0 deletions

diff --git a/ICSharpCode.NRefactory.CSharp/Parser/mcs/eval.cs b/ICSharpCode.NRefactory.CSharp/Parser/mcs/eval.cs
new file mode 100644
index 00000000..03097dfd
--- /dev/null
+++ b/ICSharpCode.NRefactory.CSharp/Parser/mcs/eval.cs
@@ -0,0 +1,1128 @@
+//
+// eval.cs: Evaluation and Hosting API for the C# compiler
+//
+// Authors:
+//   Miguel de Icaza (miguel@gnome.org)
+//   Marek Safar (marek.safar@gmail.com)
+//
+// Dual licensed under the terms of the MIT X11 or GNU GPL
+//
+// Copyright 2001, 2002, 2003 Ximian, Inc (http://www.ximian.com)
+// Copyright 2004-2011 Novell, Inc
+//
+
+using System;
+using System.Threading;
+using System.Collections.Generic;
+using System.Reflection;
+using System.Reflection.Emit;
+using System.IO;
+using System.Text;
+using System.Linq;
+
+namespace Mono.CSharp
+{
+
+	/// <summary>
+	///   Evaluator: provides an API to evaluate C# statements and
+	///   expressions dynamically.
+	/// </summary>
+	/// <remarks>
+	///   This class exposes static methods to evaluate expressions in the
+	///   current program.
+	///
+	///   To initialize the evaluator with a number of compiler
+	///   options call the Init(string[]args) method with a set of
+	///   command line options that the compiler recognizes.
+	///
+	///   To interrupt execution of a statement, you can invoke the
+	///   Evaluator.Interrupt method.
+	/// </remarks>
+	public class Evaluator {
+
+		enum ParseMode {
+			// Parse silently, do not output any error messages
+			Silent,
+
+			// Report errors during parse
+			ReportErrors,
+
+			// Auto-complete, means that the tokenizer will start producing
+			// GETCOMPLETIONS tokens when it reaches a certain point.
+			GetCompletions
+		}
+
+		static object evaluator_lock = new object ();
+		static volatile bool invoking;
+		
+		static int count;
+		static Thread invoke_thread;
+
+		readonly Dictionary<string, Tuple<FieldSpec, FieldInfo>> fields;
+
+		Type base_class;
+		bool inited;
+		int startup_files;
+
+		readonly CompilerContext ctx;
+		readonly ModuleContainer module;
+		readonly ReflectionImporter importer;
+		readonly CompilationSourceFile source_file;
+		
+		public Evaluator (CompilerSettings settings, Report report)
+		{
+			ctx = new CompilerContext (settings, report);
+
+			module = new ModuleContainer (ctx);
+			module.Evaluator = this;
+
+			source_file = new CompilationSourceFile ("{interactive}", "", 1);
+ 			source_file.NamespaceContainer = new NamespaceContainer (null, module, null, source_file);
+
+			startup_files = ctx.SourceFiles.Count;
+			ctx.SourceFiles.Add (source_file);
+
+			// FIXME: Importer needs this assembly for internalsvisibleto
+			module.SetDeclaringAssembly (new AssemblyDefinitionDynamic (module, "evaluator"));
+			importer = new ReflectionImporter (module, ctx.BuiltinTypes);
+
+			InteractiveBaseClass = typeof (InteractiveBase);
+			fields = new Dictionary<string, Tuple<FieldSpec, FieldInfo>> ();
+		}
+
+		void Init ()
+		{
+			var loader = new DynamicLoader (importer, ctx);
+
+			CompilerCallableEntryPoint.Reset ();
+			RootContext.ToplevelTypes = module;
+
+			//var startup_files = new List<string> ();
+			//foreach (CompilationUnit file in Location.SourceFiles)
+			//    startup_files.Add (file.Path);
+
+			loader.LoadReferences (module);
+			ctx.BuiltinTypes.CheckDefinitions (module);
+			module.InitializePredefinedTypes ();
+
+			inited = true;
+		}
+
+		void ParseStartupFiles ()
+		{
+			Driver d = new Driver (ctx);
+
+			Location.Initialize (ctx.SourceFiles);
+
+			for (int i = 0; i < startup_files; ++i) {
+				var sf = ctx.Settings.SourceFiles [i];
+				d.Parse (sf, module);
+			}
+		}
+
+		void Reset ()
+		{
+			CompilerCallableEntryPoint.PartialReset ();
+			
+			Location.Reset ();
+			Location.Initialize (ctx.SourceFiles);
+		}
+
+		/// <summary>
+		///   If true, turns type expressions into valid expressions
+		///   and calls the describe method on it
+		/// </summary>
+		public bool DescribeTypeExpressions;
+
+		/// <summary>
+		///   The base class for the classes that host the user generated code
+		/// </summary>
+		/// <remarks>
+		///
+		///   This is the base class that will host the code
+		///   executed by the Evaluator.  By default
+		///   this is the Mono.CSharp.InteractiveBase class
+		///   which is useful for interactive use.
+		///
+		///   By changing this property you can control the
+		///   base class and the static members that are
+		///   available to your evaluated code.
+		/// </remarks>
+		public Type InteractiveBaseClass {
+			get {
+				return base_class;
+			}
+			set {
+				base_class = value;
+
+				if (value != null && typeof (InteractiveBase).IsAssignableFrom (value))
+					InteractiveBase.Evaluator = this;
+			}
+		}
+
+		/// <summary>
+		///   Interrupts the evaluation of an expression executing in Evaluate.
+		/// </summary>
+		/// <remarks>
+		///   Use this method to interrupt long-running invocations.
+		/// </remarks>
+		public void Interrupt ()
+		{
+			if (!inited || !invoking)
+				return;
+			
+			if (invoke_thread != null)
+				invoke_thread.Abort ();
+		}
+
+		/// <summary>
+		///   Compiles the input string and returns a delegate that represents the compiled code.
+		/// </summary>
+		/// <remarks>
+		///
+		///   Compiles the input string as a C# expression or
+		///   statement, unlike the Evaluate method, the
+		///   resulting delegate can be invoked multiple times
+		///   without incurring in the compilation overhead.
+		///
+		///   If the return value of this function is null,
+		///   this indicates that the parsing was complete.
+		///   If the return value is a string it indicates
+		///   that the input string was partial and that the
+		///   invoking code should provide more code before
+		///   the code can be successfully compiled.
+		///
+		///   If you know that you will always get full expressions or
+		///   statements and do not care about partial input, you can use
+		///   the other Compile overload. 
+		///
+		///   On success, in addition to returning null, the
+		///   compiled parameter will be set to the delegate
+		///   that can be invoked to execute the code.
+		///
+	    /// </remarks>
+		public string Compile (string input, out CompiledMethod compiled)
+		{
+			if (input == null || input.Length == 0){
+				compiled = null;
+				return null;
+			}
+
+			lock (evaluator_lock){
+				if (!inited) {
+					Init ();
+					ParseStartupFiles ();
+				} else {
+					ctx.Report.Printer.Reset ();
+				}
+
+				bool partial_input;
+				CSharpParser parser = ParseString (ParseMode.Silent, input, out partial_input);
+				if (parser == null){
+					compiled = null;
+					if (partial_input)
+						return input;
+					
+					ParseString (ParseMode.ReportErrors, input, out partial_input);
+					return null;
+				}
+				
+				Class parser_result = parser.InteractiveResult;
+				compiled = CompileBlock (parser_result, parser.undo, ctx.Report);
+				return null;
+			}
+		}
+
+		/// <summary>
+		///   Compiles the input string and returns a delegate that represents the compiled code.
+		/// </summary>
+		/// <remarks>
+		///
+		///   Compiles the input string as a C# expression or
+		///   statement, unlike the Evaluate method, the
+		///   resulting delegate can be invoked multiple times
+		///   without incurring in the compilation overhead.
+		///
+		///   This method can only deal with fully formed input
+		///   strings and does not provide a completion mechanism.
+		///   If you must deal with partial input (for example for
+		///   interactive use) use the other overload. 
+		///
+		///   On success, a delegate is returned that can be used
+		///   to invoke the method.
+		///
+		/// </remarks>
+		public CompiledMethod Compile (string input)
+		{
+			CompiledMethod compiled;
+
+			// Ignore partial inputs
+			if (Compile (input, out compiled) != null){
+				// Error, the input was partial.
+				return null;
+			}
+
+			// Either null (on error) or the compiled method.
+			return compiled;
+		}
+
+		/// <summary>
+		///   Evaluates and expression or statement and returns any result values.
+		/// </summary>
+		/// <remarks>
+		///   Evaluates the input string as a C# expression or
+		///   statement.  If the input string is an expression
+		///   the result will be stored in the result variable
+		///   and the result_set variable will be set to true.
+		///
+		///   It is necessary to use the result/result_set
+		///   pair to identify when a result was set (for
+		///   example, execution of user-provided input can be
+		///   an expression, a statement or others, and
+		///   result_set would only be set if the input was an
+		///   expression.
+		///
+		///   If the return value of this function is null,
+		///   this indicates that the parsing was complete.
+		///   If the return value is a string, it indicates
+		///   that the input is partial and that the user
+		///   should provide an updated string.
+		/// </remarks>
+		public string Evaluate (string input, out object result, out bool result_set)
+		{
+			CompiledMethod compiled;
+
+			result_set = false;
+			result = null;
+
+			input = Compile (input, out compiled);
+			if (input != null)
+				return input;
+			
+			if (compiled == null)
+				return null;
+				
+			//
+			// The code execution does not need to keep the compiler lock
+			//
+			object retval = typeof (QuitValue);
+
+			try {
+				invoke_thread = System.Threading.Thread.CurrentThread;
+				invoking = true;
+				compiled (ref retval);
+			} catch (ThreadAbortException e){
+				Thread.ResetAbort ();
+				Console.WriteLine ("Interrupted!\n{0}", e);
+			} finally {
+				invoking = false;
+			}
+
+			//
+			// We use a reference to a compiler type, in this case
+			// Driver as a flag to indicate that this was a statement
+			//
+			if (!ReferenceEquals (retval, typeof (QuitValue))) {
+				result_set = true;
+				result = retval; 
+			}
+
+			return null;
+		}
+
+		public string [] GetCompletions (string input, out string prefix)
+		{
+			prefix = "";
+			if (input == null || input.Length == 0)
+				return null;
+			
+			lock (evaluator_lock){
+				if (!inited)
+					Init ();
+				
+				bool partial_input;
+				CSharpParser parser = ParseString (ParseMode.GetCompletions, input, out partial_input);
+				if (parser == null){
+					if (CSharpParser.yacc_verbose_flag != 0)
+						Console.WriteLine ("DEBUG: No completions available");
+					return null;
+				}
+				
+				Class parser_result = parser.InteractiveResult;
+
+#if NET_4_0
+				var access = AssemblyBuilderAccess.RunAndCollect;
+#else
+				var access = AssemblyBuilderAccess.Run;
+#endif
+				var a = new AssemblyDefinitionDynamic (module, "completions");
+				a.Create (AppDomain.CurrentDomain, access);
+				module.SetDeclaringAssembly (a);
+
+				// Need to setup MemberCache
+				parser_result.CreateType ();
+
+				var method = parser_result.Methods[0] as Method;
+				BlockContext bc = new BlockContext (method, method.Block, ctx.BuiltinTypes.Void);
+
+				try {
+					method.Block.Resolve (null, bc, method);
+				} catch (CompletionResult cr) {
+					prefix = cr.BaseText;
+					return cr.Result;
+				} 
+			}
+			return null;
+		}
+
+		/// <summary>
+		///   Executes the given expression or statement.
+		/// </summary>
+		/// <remarks>
+		///    Executes the provided statement, returns true
+		///    on success, false on parsing errors.  Exceptions
+		///    might be thrown by the called code.
+		/// </remarks>
+		public bool Run (string statement)
+		{
+			object result;
+			bool result_set;
+
+			return Evaluate (statement, out result, out result_set) == null;
+		}
+
+		/// <summary>
+		///   Evaluates and expression or statement and returns the result.
+		/// </summary>
+		/// <remarks>
+		///   Evaluates the input string as a C# expression or
+		///   statement and returns the value.   
+		///
+		///   This method will throw an exception if there is a syntax error,
+		///   of if the provided input is not an expression but a statement.
+		/// </remarks>
+		public object Evaluate (string input)
+		{
+			object result;
+			bool result_set;
+			
+			string r = Evaluate (input, out result, out result_set);
+
+			if (r != null)
+				throw new ArgumentException ("Syntax error on input: partial input");
+			
+			if (result_set == false)
+				throw new ArgumentException ("The expression did not set a result");
+
+			return result;
+		}
+
+		enum InputKind {
+			EOF,
+			StatementOrExpression,
+			CompilationUnit,
+			Error
+		}
+
+		//
+		// Deambiguates the input string to determine if we
+		// want to process a statement or if we want to
+		// process a compilation unit.
+		//
+		// This is done using a top-down predictive parser,
+		// since the yacc/jay parser can not deambiguage this
+		// without more than one lookahead token.   There are very
+		// few ambiguities.
+		//
+		InputKind ToplevelOrStatement (SeekableStreamReader seekable)
+		{
+			Tokenizer tokenizer = new Tokenizer (seekable, source_file, ctx);
+			
+			int t = tokenizer.token ();
+			switch (t){
+			case Token.EOF:
+				return InputKind.EOF;
+				
+			// These are toplevels
+			case Token.EXTERN:
+			case Token.OPEN_BRACKET:
+			case Token.ABSTRACT:
+			case Token.CLASS:
+			case Token.ENUM:
+			case Token.INTERFACE:
+			case Token.INTERNAL:
+			case Token.NAMESPACE:
+			case Token.PRIVATE:
+			case Token.PROTECTED:
+			case Token.PUBLIC:
+			case Token.SEALED:
+			case Token.STATIC:
+			case Token.STRUCT:
+				return InputKind.CompilationUnit;
+				
+			// Definitely expression
+			case Token.FIXED:
+			case Token.BOOL:
+			case Token.BYTE:
+			case Token.CHAR:
+			case Token.DECIMAL:
+			case Token.DOUBLE:
+			case Token.FLOAT:
+			case Token.INT:
+			case Token.LONG:
+			case Token.NEW:
+			case Token.OBJECT:
+			case Token.SBYTE:
+			case Token.SHORT:
+			case Token.STRING:
+			case Token.UINT:
+			case Token.ULONG:
+				return InputKind.StatementOrExpression;
+
+			// These need deambiguation help
+			case Token.USING:
+				t = tokenizer.token ();
+				if (t == Token.EOF)
+					return InputKind.EOF;
+
+				if (t == Token.IDENTIFIER)
+					return InputKind.CompilationUnit;
+				return InputKind.StatementOrExpression;
+
+
+			// Distinguish between:
+			//    delegate opt_anonymous_method_signature block
+			//    delegate type 
+			case Token.DELEGATE:
+				t = tokenizer.token ();
+				if (t == Token.EOF)
+					return InputKind.EOF;
+				if (t == Token.OPEN_PARENS || t == Token.OPEN_BRACE)
+					return InputKind.StatementOrExpression;
+				return InputKind.CompilationUnit;
+
+			// Distinguih between:
+			//    unsafe block
+			//    unsafe as modifier of a type declaration
+			case Token.UNSAFE:
+				t = tokenizer.token ();
+				if (t == Token.EOF)
+					return InputKind.EOF;
+				if (t == Token.OPEN_PARENS)
+					return InputKind.StatementOrExpression;
+				return InputKind.CompilationUnit;
+				
+		        // These are errors: we list explicitly what we had
+			// from the grammar, ERROR and then everything else
+
+			case Token.READONLY:
+			case Token.OVERRIDE:
+			case Token.ERROR:
+				return InputKind.Error;
+
+			// This catches everything else allowed by
+			// expressions.  We could add one-by-one use cases
+			// if needed.
+			default:
+				return InputKind.StatementOrExpression;
+			}
+		}
+		
+		//
+		// Parses the string @input and returns a CSharpParser if succeeful.
+		//
+		// if @silent is set to true then no errors are
+		// reported to the user.  This is used to do various calls to the
+		// parser and check if the expression is parsable.
+		//
+		// @partial_input: if @silent is true, then it returns whether the
+		// parsed expression was partial, and more data is needed
+		//
+		CSharpParser ParseString (ParseMode mode, string input, out bool partial_input)
+		{
+			partial_input = false;
+			Reset ();
+			Tokenizer.LocatedToken.Initialize ();
+
+			var enc = ctx.Settings.Encoding;
+			var s = new MemoryStream (enc.GetBytes (input));
+			SeekableStreamReader seekable = new SeekableStreamReader (s, enc);
+
+			InputKind kind = ToplevelOrStatement (seekable);
+			if (kind == InputKind.Error){
+				if (mode == ParseMode.ReportErrors)
+					ctx.Report.Error (-25, "Detection Parsing Error");
+				partial_input = false;
+				return null;
+			}
+
+			if (kind == InputKind.EOF){
+				if (mode == ParseMode.ReportErrors)
+					Console.Error.WriteLine ("Internal error: EOF condition should have been detected in a previous call with silent=true");
+				partial_input = true;
+				return null;
+				
+			}
+			seekable.Position = 0;
+
+			source_file.NamespaceContainer.DeclarationFound = false;
+			CSharpParser parser = new CSharpParser (seekable, source_file);
+
+			if (kind == InputKind.StatementOrExpression){
+				parser.Lexer.putback_char = Tokenizer.EvalStatementParserCharacter;
+				ctx.Settings.StatementMode = true;
+			} else {
+				parser.Lexer.putback_char = Tokenizer.EvalCompilationUnitParserCharacter;
+				ctx.Settings.StatementMode = false;
+			}
+
+			if (mode == ParseMode.GetCompletions)
+				parser.Lexer.CompleteOnEOF = true;
+
+			ReportPrinter old_printer = null;
+			if ((mode == ParseMode.Silent || mode == ParseMode.GetCompletions) && CSharpParser.yacc_verbose_flag == 0)
+				old_printer = ctx.Report.SetPrinter (new StreamReportPrinter (TextWriter.Null));
+
+			try {
+				parser.parse ();
+			} finally {
+				if (ctx.Report.Errors != 0){
+					if (mode != ParseMode.ReportErrors  && parser.UnexpectedEOF)
+						partial_input = true;
+
+					if (parser.undo != null)
+						parser.undo.ExecuteUndo ();
+
+					parser = null;
+				}
+
+				if (old_printer != null)
+					ctx.Report.SetPrinter (old_printer);
+			}
+			return parser;
+		}
+
+		CompiledMethod CompileBlock (Class host, Undo undo, Report Report)
+		{
+			string current_debug_name = "eval-" + count + ".dll";
+			++count;
+#if STATIC
+			throw new NotSupportedException ();
+#else
+			AssemblyDefinitionDynamic assembly;
+			AssemblyBuilderAccess access;
+
+			if (Environment.GetEnvironmentVariable ("SAVE") != null) {
+				access = AssemblyBuilderAccess.RunAndSave;
+				assembly = new AssemblyDefinitionDynamic (module, current_debug_name, current_debug_name);
+				assembly.Importer = importer;
+			} else {
+#if NET_4_0
+				access = AssemblyBuilderAccess.RunAndCollect;
+#else
+				access = AssemblyBuilderAccess.Run;
+#endif
+				assembly = new AssemblyDefinitionDynamic (module, current_debug_name);
+			}
+
+			assembly.Create (AppDomain.CurrentDomain, access);
+
+			Method expression_method;
+			if (host != null) {
+				var base_class_imported = importer.ImportType (base_class);
+				var baseclass_list = new List<FullNamedExpression> (1) {
+					new TypeExpression (base_class_imported, host.Location)
+				};
+
+				host.AddBasesForPart (host, baseclass_list);
+
+				host.CreateType ();
+				host.DefineType ();
+				host.Define ();
+
+				expression_method = (Method) host.Methods[0];
+			} else {
+				expression_method = null;
+			}
+
+			module.CreateType ();
+			module.Define ();
+
+			if (Report.Errors != 0){
+				if (undo != null)
+					undo.ExecuteUndo ();
+
+				return null;
+			}
+
+			if (host != null){
+				host.EmitType ();
+			}
+			
+			module.Emit ();
+			if (Report.Errors != 0){
+				if (undo != null)
+					undo.ExecuteUndo ();
+				return null;
+			}
+
+			module.CloseType ();
+			if (host != null)
+				host.CloseType ();
+
+			if (access == AssemblyBuilderAccess.RunAndSave)
+				assembly.Save ();
+
+			if (host == null)
+				return null;
+			
+			//
+			// Unlike Mono, .NET requires that the MethodInfo is fetched, it cant
+			// work from MethodBuilders.   Retarded, I know.
+			//
+			var tt = assembly.Builder.GetType (host.TypeBuilder.Name);
+			var mi = tt.GetMethod (expression_method.Name);
+
+			if (host.Fields != null) {
+				//
+				// We need to then go from FieldBuilder to FieldInfo
+				// or reflection gets confused (it basically gets confused, and variables override each
+				// other).
+				//
+				foreach (Field field in host.Fields) {
+					var fi = tt.GetField (field.Name);
+
+					Tuple<FieldSpec, FieldInfo> old;
+
+					// If a previous value was set, nullify it, so that we do
+					// not leak memory
+					if (fields.TryGetValue (field.Name, out old)) {
+						if (old.Item1.MemberType.IsStruct) {
+							//
+							// TODO: Clear fields for structs
+							//
+						} else {
+							try {
+								old.Item2.SetValue (null, null);
+							} catch {
+							}
+						}
+					}
+
+					fields[field.Name] = Tuple.Create (field.Spec, fi);
+				}
+			}
+			
+			return (CompiledMethod) System.Delegate.CreateDelegate (typeof (CompiledMethod), mi);
+#endif
+		}
+
+		/// <summary>
+		///   A sentinel value used to indicate that no value was
+		///   was set by the compiled function.   This is used to
+		///   differentiate between a function not returning a
+		///   value and null.
+		/// </summary>
+		internal static class QuitValue { }
+
+		internal Tuple<FieldSpec, FieldInfo> LookupField (string name)
+		{
+			Tuple<FieldSpec, FieldInfo> fi;
+			fields.TryGetValue (name, out fi);
+			return fi;
+		}
+
+		static string Quote (string s)
+		{
+			if (s.IndexOf ('"') != -1)
+				s = s.Replace ("\"", "\\\"");
+			
+			return "\"" + s + "\"";
+		}
+
+		public string GetUsing ()
+		{
+			StringBuilder sb = new StringBuilder ();
+			// TODO:
+			//foreach (object x in ns.using_alias_list)
+			//    sb.AppendFormat ("using {0};\n", x);
+
+			foreach (var ue in source_file.NamespaceContainer.Usings) {
+				sb.AppendFormat ("using {0};", ue.ToString ());
+				sb.Append (Environment.NewLine);
+			}
+
+			return sb.ToString ();
+		}
+
+		internal ICollection<string> GetUsingList ()
+		{
+			var res = new List<string> ();
+
+			foreach (var ue in source_file.NamespaceContainer.Usings)
+				res.Add (ue.Name);
+			return res;
+		}
+		
+		internal string [] GetVarNames ()
+		{
+			lock (evaluator_lock){
+				return new List<string> (fields.Keys).ToArray ();
+			}
+		}
+		
+		public string GetVars ()
+		{
+			lock (evaluator_lock){
+				StringBuilder sb = new StringBuilder ();
+				
+				foreach (var de in fields){
+					var fi = LookupField (de.Key);
+					object value;
+					try {
+						value = fi.Item2.GetValue (null);
+						if (value is string)
+							value = Quote ((string)value);
+					} catch {
+						value = "<error reading value>";
+					}
+
+					sb.AppendFormat ("{0} {1} = {2}", fi.Item1.MemberType.GetSignatureForError (), de.Key, value);
+					sb.AppendLine ();
+				}
+				
+				return sb.ToString ();
+			}
+		}
+
+		/// <summary>
+		///    Loads the given assembly and exposes the API to the user.
+		/// </summary>
+		public void LoadAssembly (string file)
+		{
+			var loader = new DynamicLoader (importer, ctx);
+			var assembly = loader.LoadAssemblyFile (file);
+			if (assembly == null)
+				return;
+
+			lock (evaluator_lock){
+				importer.ImportAssembly (assembly, module.GlobalRootNamespace);
+			}
+		}
+
+		/// <summary>
+		///    Exposes the API of the given assembly to the Evaluator
+		/// </summary>
+		public void ReferenceAssembly (Assembly a)
+		{
+			lock (evaluator_lock){
+				importer.ImportAssembly (a, module.GlobalRootNamespace);
+			}
+		}
+	}
+
+	
+	/// <summary>
+	///   A delegate that can be used to invoke the
+	///   compiled expression or statement.
+	/// </summary>
+	/// <remarks>
+	///   Since the Compile methods will compile
+	///   statements and expressions into the same
+	///   delegate, you can tell if a value was returned
+	///   by checking whether the returned value is of type
+	///   NoValueSet.   
+	/// </remarks>
+	
+	public delegate void CompiledMethod (ref object retvalue);
+
+	/// <summary>
+	///   The default base class for every interaction line
+	/// </summary>
+	/// <remarks>
+	///   The expressions and statements behave as if they were
+	///   a static method of this class.   The InteractiveBase class
+	///   contains a number of useful methods, but can be overwritten
+	///   by setting the InteractiveBaseType property in the Evaluator
+	/// </remarks>
+	public class InteractiveBase {
+		/// <summary>
+		///   Determines where the standard output of methods in this class will go. 
+		/// </summary>
+		public static TextWriter Output = Console.Out;
+
+		/// <summary>
+		///   Determines where the standard error of methods in this class will go. 
+		/// </summary>
+		public static TextWriter Error = Console.Error;
+
+		/// <summary>
+		///   The primary prompt used for interactive use.
+		/// </summary>
+		public static string Prompt             = "csharp> ";
+
+		/// <summary>
+		///   The secondary prompt used for interactive use (used when
+		///   an expression is incomplete).
+		/// </summary>
+		public static string ContinuationPrompt = "      > ";
+
+		/// <summary>
+		///   Used to signal that the user has invoked the  `quit' statement.
+		/// </summary>
+		public static bool QuitRequested;
+
+		public static Evaluator Evaluator;
+		
+		/// <summary>
+		///   Shows all the variables defined so far.
+		/// </summary>
+		static public void ShowVars ()
+		{
+			Output.Write (Evaluator.GetVars ());
+			Output.Flush ();
+		}
+
+		/// <summary>
+		///   Displays the using statements in effect at this point. 
+		/// </summary>
+		static public void ShowUsing ()
+		{
+			Output.Write (Evaluator.GetUsing ());
+			Output.Flush ();
+		}
+	
+		/// <summary>
+		///   Times the execution of the given delegate
+		/// </summary>
+		static public TimeSpan Time (Action a)
+		{
+			DateTime start = DateTime.Now;
+			a ();
+			return DateTime.Now - start;
+		}
+		
+		/// <summary>
+		///   Loads the assemblies from a package
+		/// </summary>
+		/// <remarks>
+		///   Loads the assemblies from a package.   This is equivalent
+		///   to passing the -pkg: command line flag to the C# compiler
+		///   on the command line. 
+		/// </remarks>
+		static public void LoadPackage (string pkg)
+		{
+			if (pkg == null){
+				Error.WriteLine ("Invalid package specified");
+				return;
+			}
+
+			string pkgout = Driver.GetPackageFlags (pkg, null);
+
+			string [] xargs = pkgout.Trim (new Char [] {' ', '\n', '\r', '\t'}).
+				Split (new Char [] { ' ', '\t'});
+
+			foreach (string s in xargs){
+				if (s.StartsWith ("-r:") || s.StartsWith ("/r:") || s.StartsWith ("/reference:")){
+					string lib = s.Substring (s.IndexOf (':')+1);
+
+					Evaluator.LoadAssembly (lib);
+					continue;
+				}
+			}
+		}
+
+		/// <summary>
+		///   Loads the assembly
+		/// </summary>
+		/// <remarks>
+		///   Loads the specified assembly and makes its types
+		///   available to the evaluator.  This is equivalent
+		///   to passing the -pkg: command line flag to the C#
+		///   compiler on the command line.
+		/// </remarks>
+		static public void LoadAssembly (string assembly)
+		{
+			Evaluator.LoadAssembly (assembly);
+		}
+
+		static public void print (object obj)
+		{
+			Output.WriteLine (obj);
+		}
+
+		static public void print (string fmt, params object [] args)
+		{
+			Output.WriteLine (fmt, args);
+		}
+		
+		/// <summary>
+		///   Returns a list of available static methods. 
+		/// </summary>
+		static public string help {
+			get {
+				return "Static methods:\n" +
+					"  Describe (object);       - Describes the object's type\n" +
+					"  LoadPackage (package);   - Loads the given Package (like -pkg:FILE)\n" +
+					"  LoadAssembly (assembly); - Loads the given assembly (like -r:ASSEMBLY)\n" +
+					"  ShowVars ();             - Shows defined local variables.\n" +
+					"  ShowUsing ();            - Show active using declarations.\n" +
+					"  Prompt                   - The prompt used by the C# shell\n" +
+					"  ContinuationPrompt       - The prompt for partial input\n" +
+					"  Time (() => { });        - Times the specified code\n" +
+					"  print (obj);             - Shorthand for Console.WriteLine\n" +
+					"  quit;                    - You'll never believe it - this quits the repl!\n" +
+					"  help;                    - This help text\n";
+			}
+		}
+
+		/// <summary>
+		///   Indicates to the read-eval-print-loop that the interaction should be finished. 
+		/// </summary>
+		static public object quit {
+			get {
+				QuitRequested = true;
+
+				// To avoid print null at the exit
+				return typeof (Evaluator.QuitValue);
+			}
+		}
+
+#if !NET_2_1
+		/// <summary>
+		///   Describes an object or a type.
+		/// </summary>
+		/// <remarks>
+		///   This method will show a textual representation
+		///   of the object's type.  If the object is a
+		///   System.Type it renders the type directly,
+		///   otherwise it renders the type returned by
+		///   invoking GetType on the object.
+		/// </remarks>
+		static public string Describe (object x)
+		{
+			if (x == null)
+				return "<null>";
+
+			var type = x as Type ?? x.GetType ();
+
+			StringWriter sw = new StringWriter ();
+			new Outline (type, sw, true, false, false).OutlineType ();
+			return sw.ToString ();
+		}
+#endif
+	}
+
+	class HoistedEvaluatorVariable : HoistedVariable
+	{
+		public HoistedEvaluatorVariable (Field field)
+			: base (null, field)
+		{
+		}
+
+		public override void EmitSymbolInfo ()
+		{
+		}
+
+		protected override FieldExpr GetFieldExpression (EmitContext ec)
+		{
+			return new FieldExpr (field, field.Location);
+		}
+	}
+
+	/// <summary>
+	///    A class used to assign values if the source expression is not void
+	///
+	///    Used by the interactive shell to allow it to call this code to set
+	///    the return value for an invocation.
+	/// </summary>
+	class OptionalAssign : SimpleAssign {
+		public OptionalAssign (Expression t, Expression s, Location loc)
+			: base (t, s, loc)
+		{
+		}
+
+		protected override Expression DoResolve (ResolveContext ec)
+		{
+			Expression clone = source.Clone (new CloneContext ());
+
+			clone = clone.Resolve (ec);
+			if (clone == null)
+				return null;
+
+			//
+			// A useful feature for the REPL: if we can resolve the expression
+			// as a type, Describe the type;
+			//
+			if (ec.Module.Evaluator.DescribeTypeExpressions){
+				var old_printer = ec.Report.SetPrinter (new SessionReportPrinter ());
+				Expression tclone;
+				try {
+					// Note: clone context cannot be shared otherwise block mapping would leak
+					tclone = source.Clone (new CloneContext ());
+					tclone = tclone.Resolve (ec, ResolveFlags.Type);
+					if (ec.Report.Errors > 0)
+						tclone = null;
+				} finally {
+					ec.Report.SetPrinter (old_printer);
+				}
+
+				if (tclone != null) {
+					Arguments args = new Arguments (1);
+					args.Add (new Argument (new TypeOf ((TypeExpr) clone, Location)));
+					return new Invocation (new SimpleName ("Describe", Location), args).Resolve (ec);
+				}
+			}
+
+			// This means its really a statement.
+			if (clone.Type.Kind == MemberKind.Void || clone is DynamicInvocation || clone is Assign) {
+				return clone;
+			}
+
+			source = clone;
+			return base.DoResolve (ec);
+		}
+	}
+
+	public class Undo
+	{
+		List<Action> undo_actions;
+		
+		public Undo ()
+		{
+		}
+
+		public void AddTypeContainer (TypeContainer current_container, TypeContainer tc)
+		{
+			if (current_container == tc){
+				Console.Error.WriteLine ("Internal error: inserting container into itself");
+				return;
+			}
+
+			if (undo_actions == null)
+				undo_actions = new List<Action> ();
+
+			var existing = current_container.Types.FirstOrDefault (l => l.MemberName.Basename == tc.MemberName.Basename);
+			if (existing != null) {
+				current_container.RemoveTypeContainer (existing);
+				existing.NamespaceEntry.SlaveDeclSpace.RemoveTypeContainer (existing);
+				undo_actions.Add (() => current_container.AddTypeContainer (existing));
+			}
+
+			undo_actions.Add (() => current_container.RemoveTypeContainer (tc));
+		}
+
+		public void ExecuteUndo ()
+		{
+			if (undo_actions == null)
+				return;
+
+			foreach (var p in undo_actions){
+				p ();
+			}
+
+			undo_actions = null;
+		}
+	}
+	
+}