/IronPython_Main/Languages/Ruby/Ruby/Runtime/RubyOps.cs

/* ****************************************************************************

 *

 * Copyright (c) Microsoft Corporation. 

 *

 * This source code is subject to terms and conditions of the Apache License, Version 2.0. A 

 * copy of the license can be found in the License.html file at the root of this distribution. If 

 * you cannot locate the  Apache License, Version 2.0, please send an email to 

 * ironruby@microsoft.com. By using this source code in any fashion, you are agreeing to be bound 

 * by the terms of the Apache License, Version 2.0.

 *

 * You must not remove this notice, or any other, from this software.

 *

 *

 * ***************************************************************************/



#if !CLR2

using MSA = System.Linq.Expressions;

#else

using MSA = Microsoft.Scripting.Ast;

#endif



using System;

using System.Collections;

using System.Collections.Generic;

using System.Diagnostics;

using System.Dynamic;

using System.Globalization;

using System.IO;

using System.Reflection;

using System.Runtime.CompilerServices;

using System.Runtime.Serialization;

using System.Threading;

using IronRuby.Builtins;

using IronRuby.Compiler;

using IronRuby.Compiler.Generation;

using IronRuby.Runtime.Calls;

using Microsoft.Scripting;

using Microsoft.Scripting.Interpreter;

using Microsoft.Scripting.Math;

using Microsoft.Scripting.Runtime;

using Microsoft.Scripting.Utils;

using IronRuby.Compiler.Ast;

using IronRuby.Runtime.Conversions;



namespace IronRuby.Runtime {

    [ReflectionCached, CLSCompliant(false)]

    public static partial class RubyOps {

        [Emitted]

        public static readonly object DefaultArgument = new object();

        

        // Returned by a virtual site if a base call should be performed.

        [Emitted]

        public static readonly object ForwardToBase = new object();



        // an instance of a dummy type that causes any rule based on instance type check to fail

        private sealed class _NeedsUpdate {

        }



        [Emitted]

        public static readonly object NeedsUpdate = new _NeedsUpdate();



        #region Scopes



        [Emitted]

        public static MutableTuple GetLocals(RubyScope/*!*/ scope) {

            return scope.Locals;

        }



        [Emitted]

        public static MutableTuple GetParentLocals(RubyScope/*!*/ scope) {

            return scope.Parent.Locals;

        }



        [Emitted]

        public static RubyScope/*!*/ GetParentScope(RubyScope/*!*/ scope) {

            return scope.Parent;

        }



        [Emitted]

        public static Proc GetMethodBlockParameter(RubyScope/*!*/ scope) {

            var methodScope = scope.GetInnerMostMethodScope();

            return methodScope != null ? methodScope.BlockParameter : null;

        }



        [Emitted]

        public static object GetMethodBlockParameterSelf(RubyScope/*!*/ scope) {

            Proc proc = scope.GetInnerMostMethodScope().BlockParameter;

            Debug.Assert(proc != null, "CreateBfcForYield is called before this method and it checks non-nullity");

            return proc.Self;

        }



        [Emitted]

        public static object GetProcSelf(Proc/*!*/ proc) {

            return proc.Self;

        }



        [Emitted]

        public static int GetProcArity(Proc/*!*/ proc) {

            return proc.Dispatcher.Arity;

        }



        [Emitted]

        public static void InitializeScope(RubyScope/*!*/ scope, MutableTuple locals, string[] variableNames, 

            InterpretedFrame interpretedFrame) {



            if (!scope.LocalsInitialized) {

                scope.SetLocals(locals, variableNames ?? ArrayUtils.EmptyStrings);

            }

            scope.InterpretedFrame = interpretedFrame;

        }

        

        [Emitted]

        public static void InitializeScopeNoLocals(RubyScope/*!*/ scope, InterpretedFrame interpretedFrame) {

            scope.InterpretedFrame = interpretedFrame;

        }



        [Emitted]

        public static void SetDataConstant(RubyScope/*!*/ scope, string/*!*/ dataPath, int dataOffset) {

            Debug.Assert(dataOffset >= 0);

            RubyFile dataFile;

            RubyContext context = scope.RubyContext;

            if (context.DomainManager.Platform.FileExists(dataPath)) {

                dataFile = new RubyFile(context, dataPath, IOMode.ReadOnly);

                dataFile.Seek(dataOffset, SeekOrigin.Begin);

            } else {

                dataFile = null;

            }



            context.ObjectClass.SetConstant("DATA", dataFile);

        }



        [Emitted]

        public static RubyModuleScope/*!*/ CreateModuleScope(MutableTuple locals, string[] variableNames, 

            RubyScope/*!*/ parent, RubyModule/*!*/ module) {



            if (parent.RubyContext != module.Context) {

                throw RubyExceptions.CreateTypeError("Cannot open a module `{0}' defined in a foreign runtime #{1}", module.Name, module.Context.RuntimeId);

            }



            RubyModuleScope scope = new RubyModuleScope(parent, module);

            scope.SetDebugName((module.IsClass ? "class" : "module") + " " + module.Name);

            scope.SetLocals(locals, variableNames ?? ArrayUtils.EmptyStrings);

            return scope;

        }



        [Emitted]

        public static RubyMethodScope/*!*/ CreateMethodScope(MutableTuple locals, string[] variableNames, int visibleParameterCount,

            RubyScope/*!*/ parentScope, RubyModule/*!*/ declaringModule, string/*!*/ definitionName, 

            object selfObject, Proc blockParameter, InterpretedFrame interpretedFrame) {



            return new RubyMethodScope(

                locals, variableNames ?? ArrayUtils.EmptyStrings, visibleParameterCount,

                parentScope, declaringModule, definitionName, selfObject, blockParameter,

                interpretedFrame

            );            

        }



        [Emitted]

        public static RubyScope/*!*/ CreateFileInitializerScope(MutableTuple locals, string[] variableNames, RubyScope/*!*/ parent) {

            return new RubyFileInitializerScope(locals, variableNames ?? ArrayUtils.EmptyStrings, parent);

        }



        [Emitted]

        public static RubyBlockScope/*!*/ CreateBlockScope(MutableTuple locals, string[] variableNames, 

            BlockParam/*!*/ blockParam, object selfObject, InterpretedFrame interpretedFrame) {



            return new RubyBlockScope(locals, variableNames ?? ArrayUtils.EmptyStrings, blockParam, selfObject, interpretedFrame);

        }



        [Emitted]

        public static void TraceMethodCall(RubyMethodScope/*!*/ scope, string fileName, int lineNumber) {

            // MRI: 

            // Reports DeclaringModule even though an aliased method in a sub-module is called.

            // Also works for singleton module-function, which shares DeclaringModule with instance module-function.

            RubyModule module = scope.DeclaringModule;

            scope.RubyContext.ReportTraceEvent("call", scope, module, scope.DefinitionName, fileName, lineNumber);

        }



        [Emitted]

        public static void TraceMethodReturn(RubyMethodScope/*!*/ scope, string fileName, int lineNumber) {

            RubyModule module = scope.DeclaringModule;

            scope.RubyContext.ReportTraceEvent("return", scope, module, scope.DefinitionName, fileName, lineNumber);

        }



        [Emitted]

        public static void TraceBlockCall(RubyBlockScope/*!*/ scope, BlockParam/*!*/ block, string fileName, int lineNumber) {

            var method = block.Proc.Method;

            if (method != null) {

                scope.RubyContext.ReportTraceEvent("call", scope, method.DeclaringModule, method.DefinitionName, fileName, lineNumber);

            }

        }



        [Emitted]

        public static void TraceBlockReturn(RubyBlockScope/*!*/ scope, BlockParam/*!*/ block, string fileName, int lineNumber) {

            var method = block.Proc.Method;

            if (method != null) {

                scope.RubyContext.ReportTraceEvent("return", scope, method.DeclaringModule, method.DefinitionName, fileName, lineNumber);

            }

        }



        [Emitted]

        public static void PrintInteractiveResult(RubyScope/*!*/ scope, MutableString/*!*/ value) {

            var writer = scope.RubyContext.DomainManager.SharedIO.OutputStream;

            writer.WriteByte((byte)'=');

            writer.WriteByte((byte)'>');

            writer.WriteByte((byte)' ');

            var bytes = value.ToByteArray();

            writer.Write(bytes, 0, bytes.Length);

            writer.WriteByte((byte)'\r');

            writer.WriteByte((byte)'\n');

        }



        [Emitted]

        public static object GetLocalVariable(RubyScope/*!*/ scope, string/*!*/ name) {

            return scope.ResolveLocalVariable(name);

        }



        [Emitted]

        public static object SetLocalVariable(object value, RubyScope/*!*/ scope, string/*!*/ name) {

            return scope.ResolveAndSetLocalVariable(name, value);

        }



        [Emitted]

        public static VersionHandle/*!*/ GetSelfClassVersionHandle(RubyScope/*!*/ scope) {

            return scope.SelfImmediateClass.Version;

        }



        #endregion



        #region Context



        [Emitted]

        public static RubyContext/*!*/ GetContextFromModule(RubyModule/*!*/ module) {

            return module.Context;

        }

        

        [Emitted]

        public static RubyContext/*!*/ GetContextFromIRubyObject(IRubyObject/*!*/ obj) {

            return obj.ImmediateClass.Context;

        }

        

        [Emitted]

        public static RubyContext/*!*/ GetContextFromScope(RubyScope/*!*/ scope) {

            return scope.RubyContext;

        }



        [Emitted]

        public static RubyContext/*!*/ GetContextFromMethod(RubyMethod/*!*/ method) {

            return method.Info.Context;

        }



        [Emitted]

        public static RubyContext/*!*/ GetContextFromBlockParam(BlockParam/*!*/ block) {

            return block.RubyContext;

        }



        [Emitted]

        public static RubyContext/*!*/ GetContextFromProc(Proc/*!*/ proc) {

            return proc.LocalScope.RubyContext;

        }



        [Emitted]

        public static RubyScope/*!*/ GetEmptyScope(RubyContext/*!*/ context) {

            return context.EmptyScope;

        }



        [Emitted]

        public static Scope/*!*/ GetGlobalScopeFromScope(RubyScope/*!*/ scope) {

            return scope.GlobalScope.Scope;

        }



        #endregion



        #region Blocks



        [Emitted]

        public static Proc InstantiateBlock(RubyScope/*!*/ scope, object self, BlockDispatcher/*!*/ dispatcher) {

            return (dispatcher.Method != null) ? new Proc(ProcKind.Block, self, scope, dispatcher) : null;

        }

        [Emitted]

        public static Proc InstantiateLambda(RubyScope/*!*/ scope, object self, BlockDispatcher/*!*/ dispatcher) {

            return (dispatcher.Method != null) ? new Proc(ProcKind.Lambda, self, scope, dispatcher) : null;

        }



        [Emitted]

        public static Proc/*!*/ DefineBlock(RubyScope/*!*/ scope, object self, BlockDispatcher/*!*/ dispatcher, object/*!*/ clrMethod) {

            // DLR closures should not be used:

            Debug.Assert(!(((Delegate)clrMethod).Target is Closure) || ((Closure)((Delegate)clrMethod).Target).Locals == null);

            return new Proc(ProcKind.Block, self, scope, dispatcher.SetMethod(clrMethod));

        }



        [Emitted]

        public static Proc/*!*/ DefineLambda(RubyScope/*!*/ scope, object self, BlockDispatcher/*!*/ dispatcher, object/*!*/ clrMethod) {

            // DLR closures should not be used:

            Debug.Assert(!(((Delegate)clrMethod).Target is Closure) || ((Closure)((Delegate)clrMethod).Target).Locals == null);

            return new Proc(ProcKind.Lambda, self, scope, dispatcher.SetMethod(clrMethod));

        }



        /// <summary>

        /// Used in a method call with a block to reset proc-kind when the call is retried

        /// </summary>

        [Emitted]

        public static void InitializeBlock(Proc/*!*/ proc) {

            Assert.NotNull(proc);

            proc.Kind = ProcKind.Block;

        }



        /// <summary>

        /// Implements END block - like if it was a call to at_exit { ... } library method.

        /// </summary>

        [Emitted]

        public static void RegisterShutdownHandler(Proc/*!*/ proc) {

            proc.LocalScope.RubyContext.RegisterShutdownHandler(proc);

        }



        #endregion



        #region Yield: TODO: generate



        [Emitted] 

        public static object Yield0(Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.Invoke(blockParam, self, procArg);

            } catch(EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object Yield1(object arg1, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.Invoke(blockParam, self, procArg, arg1);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        // YieldNoAutoSplat1 uses InvokeNoAutoSplat instead of Invoke (used by Call1)

        internal static object YieldNoAutoSplat1(object arg1, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.InvokeNoAutoSplat(blockParam, self, procArg, arg1);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object Yield2(object arg1, object arg2, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.Invoke(blockParam, self, procArg, arg1, arg2);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object Yield3(object arg1, object arg2, object arg3, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.Invoke(blockParam, self, procArg, arg1, arg2, arg3);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object Yield4(object arg1, object arg2, object arg3, object arg4, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.Invoke(blockParam, self, procArg, arg1, arg2, arg3, arg4);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object YieldN(object[]/*!*/ args, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            Debug.Assert(args.Length > BlockDispatcher.MaxBlockArity);



            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.Invoke(blockParam, self, procArg, args);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        internal static object Yield(object[]/*!*/ args, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            switch (args.Length) {

                case 0: return RubyOps.Yield0(procArg, self, blockParam);

                case 1: return RubyOps.Yield1(args[0], procArg, self, blockParam);

                case 2: return RubyOps.Yield2(args[0], args[1], procArg, self, blockParam);

                case 3: return RubyOps.Yield3(args[0], args[1], args[2], procArg, self, blockParam);

                case 4: return RubyOps.Yield4(args[0], args[1], args[2], args[3], procArg, self, blockParam);

                default: return RubyOps.YieldN(args, procArg, self, blockParam); 

            }

        }



        [Emitted]

        public static object YieldSplat0(IList/*!*/ splattee, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.InvokeSplat(blockParam, self, procArg, splattee);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object YieldSplat1(object arg1, IList/*!*/ splattee, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.InvokeSplat(blockParam, self, procArg, arg1, splattee);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object YieldSplat2(object arg1, object arg2, IList/*!*/ splattee, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.InvokeSplat(blockParam, self, procArg, arg1, arg2, splattee);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object YieldSplat3(object arg1, object arg2, object arg3, IList/*!*/ splattee, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.InvokeSplat(blockParam, self, procArg, arg1, arg2, arg3, splattee);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object YieldSplat4(object arg1, object arg2, object arg3, object arg4, IList/*!*/ splattee, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.InvokeSplat(blockParam, self, procArg, arg1, arg2, arg3, arg4, splattee);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object YieldSplatN(object[]/*!*/ args, IList/*!*/ splattee, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.InvokeSplat(blockParam, self, procArg, args, splattee);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        [Emitted]

        public static object YieldSplatNRhs(object[]/*!*/ args, IList/*!*/ splattee, object rhs, Proc procArg, object self, BlockParam/*!*/ blockParam) {

            object result;

            var proc = blockParam.Proc;

            try {

                result = proc.Dispatcher.InvokeSplatRhs(blockParam, self, procArg, args, splattee, rhs);

            } catch (EvalUnwinder evalUnwinder) {

                result = blockParam.GetUnwinderResult(evalUnwinder);

            }



            return result;

        }



        #endregion



        #region Methods



        [Emitted] // MethodDeclaration:

        public static object DefineMethod(object target, RubyScope/*!*/ scope, RubyMethodBody/*!*/ body) {

            Assert.NotNull(body, scope);



            RubyModule instanceOwner, singletonOwner;

            RubyMemberFlags instanceFlags, singletonFlags;

            bool moduleFunction = false;



            if (body.HasTarget) {

                if (!RubyUtils.CanDefineSingletonMethod(target)) {

                    throw RubyExceptions.CreateTypeError("can't define singleton method for literals");

                }



                instanceOwner = null;

                instanceFlags = RubyMemberFlags.Invalid;

                singletonOwner = scope.RubyContext.GetOrCreateSingletonClass(target);

                singletonFlags = RubyMemberFlags.Public;

            } else {

                var attributesScope = scope.GetMethodAttributesDefinitionScope();

                if ((attributesScope.MethodAttributes & RubyMethodAttributes.ModuleFunction) == RubyMethodAttributes.ModuleFunction) {

                    // Singleton module-function's scope points to the instance method's RubyMemberInfo.

                    // This affects:

                    // 1) super call

                    //    Super call is looking for Method.DeclaringModule while searching MRO, which would fail if the singleton module-function

                    //    was in MRO. Since module-function can only be used on module the singleton method could only be on module's singleton.

                    //    Module's singleton is never part of MRO so we are safe.

                    // 2) trace

                    //    Method call trace reports non-singleton module.



                    // MRI 1.8: instance method owner is self -> it is possible (via define_method) to define m.f. on a class (bug)

                    // MRI 1.9: instance method owner GetMethodDefinitionOwner

                    // MRI allows to define m.f. on classes but then doesn't work correctly with it.

                    instanceOwner = scope.GetMethodDefinitionOwner();

                    if (instanceOwner.IsClass) {

                        throw RubyExceptions.CreateTypeError("A module function cannot be defined on a class.");

                    }



                    instanceFlags = RubyMemberFlags.Private;

                    singletonOwner = instanceOwner.GetOrCreateSingletonClass();

                    singletonFlags = RubyMemberFlags.Public;

                    moduleFunction = true;

                } else {

                    instanceOwner = scope.GetMethodDefinitionOwner();

                    instanceFlags = (RubyMemberFlags)RubyUtils.GetSpecialMethodVisibility(attributesScope.Visibility, body.Name);

                    singletonOwner = null;

                    singletonFlags = RubyMemberFlags.Invalid;

                }

            }

            

            RubyMethodInfo instanceMethod = null, singletonMethod = null;



            if (instanceOwner != null) {

                SetMethod(scope.RubyContext, instanceMethod =

                    new RubyMethodInfo(body, scope, instanceOwner, instanceFlags)

                );

            }



            if (singletonOwner != null) {

                SetMethod(scope.RubyContext, singletonMethod =

                    new RubyMethodInfo(body, scope, singletonOwner, singletonFlags)

                );

            }



            // the method's scope saves the result => singleton module-function uses instance-method

            var method = instanceMethod ?? singletonMethod;



            method.DeclaringModule.MethodAdded(body.Name);



            if (moduleFunction) {

                Debug.Assert(!method.DeclaringModule.IsClass);

                method.DeclaringModule.GetOrCreateSingletonClass().MethodAdded(body.Name);

            }



            return null;

        }



        private static void SetMethod(RubyContext/*!*/ callerContext, RubyMethodInfo/*!*/ method) {

            var owner = method.DeclaringModule;



            // Do not trigger the add-method event just yet, we need to assign the result into closure before executing any user code.

            // If the method being defined is "method_added" itself, we would call that method before the info gets assigned to the closure.

            owner.SetMethodNoEvent(callerContext, method.DefinitionName, method);



            // expose RubyMethod in the scope (the method is bound to the main singleton instance):

            if (owner.GlobalScope != null) {

                RubyOps.ScopeSetMember(

                    owner.GlobalScope.Scope,

                    method.DefinitionName,

                    new RubyMethod(owner.GlobalScope.MainObject, method, method.DefinitionName)

                );

            }

        }



        [Emitted] // AliasStatement:

        public static void AliasMethod(RubyScope/*!*/ scope, string/*!*/ newName, string/*!*/ oldName) {

            scope.GetMethodDefinitionOwner().AddMethodAlias(newName, oldName);

        }



        [Emitted] // UndefineMethod:

        public static void UndefineMethod(RubyScope/*!*/ scope, string/*!*/ name) {

            RubyModule owner = scope.GetMethodDefinitionOwner();



            if (!owner.ResolveMethod(name, VisibilityContext.AllVisible).Found) {

                throw RubyExceptions.CreateUndefinedMethodError(owner, name);

            }

            owner.UndefineMethod(name);

        }



        #endregion



        #region Modules



        [Emitted]

        public static RubyModule/*!*/ DefineGlobalModule(RubyScope/*!*/ scope, string/*!*/ name) {

            return DefineModule(scope, scope.Top.TopModuleOrObject, name);

        }



        [Emitted]

        public static RubyModule/*!*/ DefineNestedModule(RubyScope/*!*/ scope, string/*!*/ name) {

            return DefineModule(scope, scope.GetInnerMostModuleForConstantLookup(), name);

        }



        [Emitted]

        public static RubyModule/*!*/ DefineModule(RubyScope/*!*/ scope, object target, string/*!*/ name) {

            return DefineModule(scope, RubyUtils.GetModuleFromObject(scope, target), name);

        }



        // thread-safe:

        private static RubyModule/*!*/ DefineModule(RubyScope/*!*/ scope, RubyModule/*!*/ owner, string/*!*/ name) {

            Assert.NotNull(scope, owner);



            ConstantStorage existing;

            if (owner.TryGetConstant(scope.GlobalScope, name, out existing)) {

                RubyModule module = existing.Value as RubyModule;

                if (module == null || module.IsClass) {

                    throw RubyExceptions.CreateTypeError(String.Format("{0} is not a module", name));

                }

                return module;

            } else {

                // create class/module object:

                return owner.Context.DefineModule(owner, name);

            }

        }



        #endregion



        #region Classes



        [Emitted]

        public static RubyClass/*!*/ DefineSingletonClass(RubyScope/*!*/ scope, object obj) {

            if (!RubyUtils.HasSingletonClass(obj)) {

                throw RubyExceptions.CreateTypeError(String.Format("no virtual class for {0}", scope.RubyContext.GetClassOf(obj).Name));

            }

            return scope.RubyContext.GetOrCreateSingletonClass(obj);

        }



        [Emitted] 

        public static RubyModule/*!*/ DefineGlobalClass(RubyScope/*!*/ scope, string/*!*/ name, object superClassObject) {

            return DefineClass(scope, scope.Top.TopModuleOrObject, name, superClassObject);

        }



        [Emitted]

        public static RubyModule/*!*/ DefineNestedClass(RubyScope/*!*/ scope, string/*!*/ name, object superClassObject) {

            return DefineClass(scope, scope.GetInnerMostModuleForConstantLookup(), name, superClassObject);

        }



        [Emitted]

        public static RubyModule/*!*/ DefineClass(RubyScope/*!*/ scope, object target, string/*!*/ name, object superClassObject) {

            return DefineClass(scope, RubyUtils.GetModuleFromObject(scope, target), name, superClassObject);

        }



        // thread-safe:

        private static RubyClass/*!*/ DefineClass(RubyScope/*!*/ scope, RubyModule/*!*/ owner, string/*!*/ name, object superClassObject) {

            Assert.NotNull(owner);

            RubyClass superClass = ToSuperClass(owner.Context, superClassObject);



            ConstantStorage existing;

            if (owner.IsObjectClass

                ? owner.TryResolveConstant(scope.GlobalScope, name, out existing)

                : owner.TryGetConstant(scope.GlobalScope, name, out existing)) {



                RubyClass cls = existing.Value as RubyClass;

                if (cls == null || !cls.IsClass) {

                    throw RubyExceptions.CreateTypeError("{0} is not a class", name);

                }



                if (superClassObject != null && !ReferenceEquals(cls.SuperClass, superClass)) {

                    throw RubyExceptions.CreateTypeError("superclass mismatch for class {0}", name);

                }

                return cls;

            } else {

                return owner.Context.DefineClass(owner, name, superClass, null);

            }

        }



        private static RubyClass/*!*/ ToSuperClass(RubyContext/*!*/ ec, object superClassObject) {

            if (superClassObject != null) {

                RubyClass superClass = superClassObject as RubyClass;

                if (superClass == null) {

                    throw RubyExceptions.CreateTypeError("superclass must be a Class ({0} given)", ec.GetClassOf(superClassObject).Name);

                }



                if (superClass.IsSingletonClass) {

                    throw RubyExceptions.CreateTypeError("can't make subclass of virtual class");

                }



                return superClass;

            } else {

                return ec.ObjectClass;

            }

        }



        #endregion



        #region Constants



        /// <summary>

        /// A

        /// ::A

        /// </summary>

        [Emitted]

        public static object GetUnqualifiedConstant(RubyScope/*!*/ scope, ConstantSiteCache/*!*/ cache, string/*!*/ name, bool isGlobal) {

            object result = null;

            RubyModule missingConstantOwner;

            var context = scope.RubyContext;

            using (context.ClassHierarchyLocker()) {

                // Thread safety:

                // Another thread could have already updated the value, so the site version might be the same as CAV.

                // We do the lookup anyways since it is no-op and this only happens rarely.

                //

                // An important invariant holds here: in any time after initialized for the first time the Value field contains a valid value.

                // Threads can read an older value (the previous version) but that is still correct since we don't guarantee immediate

                // propagation of the constant write to all readers.

                // 

                // if (site.Version = CAV) {

                //   <- another thread could increment CAV here - we may return old or new value (both are ok)

                //   value = site.Value;

                // } else {

                //   <- another thread could get here as well and update the site before we get to update it.

                //   GetConstant(...)

                // }



                // Constants might be updated during constant resolution due to autoload. 

                // Any such updates need to invalidate the cache hence we need to capture the version before resolving the constant.

                int newVersion = context.ConstantAccessVersion;



                ConstantStorage storage;

                if (!isGlobal) {

                    missingConstantOwner = scope.TryResolveConstantNoLock(scope.GlobalScope, name, out storage);

                } else if (context.ObjectClass.TryResolveConstantNoLock(scope.GlobalScope, name, out storage)) {

                    missingConstantOwner = null;

                } else {

                    missingConstantOwner = context.ObjectClass;

                }



                object newCacheValue;

                if (missingConstantOwner == null) {

                    if (storage.WeakValue != null) {

                        result = storage.Value;

                        newCacheValue = storage.WeakValue;

                    } else {

                        result = newCacheValue = storage.Value;

                    }

                } else {

                    newCacheValue = ConstantSiteCache.WeakMissingConstant;

                }



                cache.Update(newCacheValue, newVersion);

            }



            if (missingConstantOwner != null) {

                result = missingConstantOwner.ConstantMissing(name);

            }



            return result;

        }



        /// <summary>

        /// A1::..::AN

        /// ::A1::..::AN

        /// </summary>

        [Emitted]

        public static object GetQualifiedConstant(RubyScope/*!*/ scope, ConstantSiteCache/*!*/ cache, string/*!*/[]/*!*/ qualifiedName, bool isGlobal) {

            var globalScope = scope.GlobalScope;

            var context = globalScope.Context;



            using (context.ClassHierarchyLocker()) {

                int newVersion = context.ConstantAccessVersion;

                

                ConstantStorage storage;

                bool anyMissing;

                RubyModule topModule = isGlobal ? context.ObjectClass : null;

                object result = ResolveQualifiedConstant(scope, qualifiedName, topModule, true, out storage, out anyMissing);



                // cache result only if no constant was missing:

                if (!anyMissing) {

                    Debug.Assert(result == storage.Value);

                    cache.Update(storage.WeakValue ?? result, newVersion);

                }



                return result;

            }

        }



        /// <summary>

        /// {expr}::A1::..::AN

        /// </summary>

        [Emitted]

        public static object GetExpressionQualifiedConstant(object target, RubyScope/*!*/ scope, ExpressionQualifiedConstantSiteCache/*!*/ cache,

            string/*!*/[]/*!*/ qualifiedName) {

            RubyModule module = target as RubyModule;

            if (module == null) {

                throw RubyUtils.CreateNotModuleException(scope, target);

            }



            var condition = cache.Condition;

            RubyContext context = module.Context;



            // Note that the module can be bound to another runtime:

            if (module.Id == condition.ModuleId && context.ConstantAccessVersion == condition.Version) {

                object value = cache.Value;

                if (value.GetType() == typeof(WeakReference)) {

                    return ((WeakReference)value).Target;

                } else {

                    return value;

                }

            }



            using (context.ClassHierarchyLocker()) {

                int newVersion = context.ConstantAccessVersion;

                

                ConstantStorage storage;

                bool anyMissing;

                object result = ResolveQualifiedConstant(scope, qualifiedName, module, true, out storage, out anyMissing);



                // cache result only if no constant was missing:

                if (!anyMissing) {

                    Debug.Assert(result == storage.Value);

                    cache.Update(storage.WeakValue ?? result, newVersion, module);

                }



                return result;

            }

        }



        /// <summary>

        /// defined? A

        /// </summary>

        [Emitted]

        public static bool IsDefinedUnqualifiedConstant(RubyScope/*!*/ scope, IsDefinedConstantSiteCache/*!*/ cache, string/*!*/ name) {

            var context = scope.RubyContext;

            using (context.ClassHierarchyLocker()) {

                int newVersion = context.ConstantAccessVersion;

                

                ConstantStorage storage;

                bool exists = scope.TryResolveConstantNoLock(null, name, out storage) == null;

                cache.Update(exists, newVersion);

                return exists;

            }

        }



        /// <summary>

        /// defined? ::A

        /// </summary>

        [Emitted]

        public static bool IsDefinedGlobalConstant(RubyScope/*!*/ scope, IsDefinedConstantSiteCache/*!*/ cache, string/*!*/ name) {

            var context = scope.RubyContext;

            using (context.ClassHierarchyLocker()) {

                int newVersion = context.ConstantAccessVersion;



                ConstantStorage storage;

                bool exists = context.ObjectClass.TryResolveConstantNoLock(null, name, out storage);

                cache.Update(exists, newVersion);

                return exists;

            }

        }



        /// <summary>

        /// defined? A1::..::AN

        /// defined? ::A1::..::AN

        /// </summary>

        [Emitted]

        public static bool IsDefinedQualifiedConstant(RubyScope/*!*/ scope, IsDefinedConstantSiteCache/*!*/ cache,

            string/*!*/[]/*!*/ qualifiedName, bool isGlobal) {



            var context = scope.RubyContext;

            using (context.ClassHierarchyLocker()) {

                int newVersion = context.ConstantAccessVersion;



                ConstantStorage storage;

                bool anyMissing;

                RubyModule topModule = isGlobal ? context.ObjectClass : null;

                RubyModule owner;

                try {

                    owner = ResolveQualifiedConstant(scope, qualifiedName, topModule, false, out storage, out anyMissing) as RubyModule;

                } catch {

                    // autoload can raise an exception

                    scope.RubyContext.SetCurrentException(null);

                    return false;

                }

                

                // Note that the owner could be another runtime's module:

                bool exists = owner != null && owner.TryResolveConstant(context, null, qualifiedName[qualifiedName.Length - 1], out storage);

                

                // cache result only if no constant was missing:

                if (!anyMissing) {

                    cache.Update(exists, newVersion);

                }



                return exists;

            }

        }



        /// <summary>

        /// defined? {expr}::A

        /// defined? {expr}::A1::..::AN

        /// </summary>

        [Emitted]

        public static bool IsDefinedExpressionQualifiedConstant(object target, RubyScope/*!*/ scope,

            ExpressionQualifiedIsDefinedConstantSiteCache/*!*/ cache, string/*!*/[]/*!*/ qualifiedName) {



            RubyModule module = target as RubyModule;

            if (module == null) {

                return false;

            }



            var condition = cache.Condition;

            RubyContext context = module.Context;



            // Note that the module can be bound to another runtime:

            if (module.Id == condition.ModuleId && context.ConstantAccessVersion == condition.Version) {

                return cache.Value;

            }



            using (context.ClassHierarchyLocker()) {

                int newVersion = context.ConstantAccessVersion;



                ConstantStorage storage;

                bool exists;

                if (qualifiedName.Length == 1) {

                    // Note that the owner could be another runtime's module:

                    exists = module.TryResolveConstant(context, null, qualifiedName[0], out storage);

                } else {

                    bool anyMissing;

                    RubyModule owner;

                    try {

                        owner = ResolveQualifiedConstant(scope, qualifiedName, module, false, out storage, out anyMissing) as RubyModule;

                    } catch {

                        // autoload can raise an exception:

                        return false;

                    }



                    // Note that the owner could be another runtime's module:

                    exists = owner != null && owner.TryResolveConstant(context, null, qualifiedName[qualifiedName.Length - 1], out storage);



                    // cache result only if no constant was missing:

                    if (anyMissing) {

                        return exists;

                    } 

                }



                cache.Update(exists, newVersion, module);

                return exists;

            }

        }



        private static object ResolveQualifiedConstant(RubyScope/*!*/ scope, string/*!*/[]/*!*/ qualifiedName, RubyModule topModule, bool isGet,

            out ConstantStorage storage, out bool anyMissing) {



            Debug.Assert(qualifiedName.Length >= 2 || qualifiedName.Length == 1 && isGet);

            RubyContext context = scope.RubyContext;

            context.RequiresClassHierarchyLock();



            RubyModule missingConstantOwner;

            RubyGlobalScope globalScope = scope.GlobalScope;

            int nameCount = (isGet) ? qualifiedName.Length : qualifiedName.Length - 1;



            string name = qualifiedName[0];

            if (topModule == null) {

                missingConstantOwner = scope.TryResolveConstantNoLock(globalScope, name, out storage);

            } else if (topModule.TryResolveConstant(context, globalScope, name, out storage)) {

                missingConstantOwner = null;

            } else {

                missingConstantOwner = topModule;

            }



            object result;

            if (missingConstantOwner == null) {

                result = storage.Value;

                anyMissing = false;

            } else {

                anyMissing = true;

                using (context.ClassHierarchyUnlocker()) {

                    result = missingConstantOwner.ConstantMissing(name);

                }

            }



            for (int i = 1; i < nameCount; i++) {

                RubyModule owner = RubyUtils.GetModuleFromObject(scope, result);

                // Note that the owner could be another runtime's module:

                name = qualifiedName[i];

                if (owner.TryResolveConstant(context, globalScope, name, out storage)) {

                    

                    // Constant write updates constant version in a single runtime only. 

                    // Therefore if the chain mixes modules from different runtimes we cannot cache the result.

                    if (owner.Context != context) {

                        anyMissing = true;

                    }

                    

                    result = storage.Value;

                } else {

                    anyMissing = true;

                    using (context.ClassHierarchyUnlocker()) {

                        result = owner.ConstantMissing(name);

                    }

                }

            }



            return result;

        }



        [Emitted]

        public static object GetMissingConstant(RubyScope/*!*/ scope, ConstantSiteCache/*!*/ cache, string/*!*/ name) {

            return scope.GetInnerMostModuleForConstantLookup().ConstantMissing(name);

        }



        [Emitted]

        public static object GetGlobalMissingConstant(RubyScope/*!*/ scope, ConstantSiteCache/*!*/ cache, string/*!*/ name) {

            return scope.RubyContext.ObjectClass.ConstantMissing(name);

        }





        [Emitted] // ConstantVariable:

        public static object SetGlobalConstant(object value, RubyScope/*!*/ scope, string/*!*/ name) {

            RubyUtils.SetConstant(scope.RubyContext.ObjectClass, name, value);

            return value;

        }



        [Emitted] // ConstantVariable:

        public static object SetUnqualifiedConstant(object value, RubyScope/*!*/ scope, string/*!*/ name) {

            RubyUtils.SetConstant(scope.GetInnerMostModuleForConstantLookup(), name, value);

            return value;

        }



        [Emitted] // ConstantVariable:

        public static object SetQualifiedConstant(object value, object target, RubyScope/*!*/ scope, string/*!*/ name) {

            RubyUtils.SetConstant(RubyUtils.GetModuleFromObject(scope, target), name, value);

            return value;

        }



        #endregion



        // MakeArray*

        public const int OptimizedOpCallParamCount = 5;

        

        #region MakeArray

        

        [Emitted]

        public static RubyArray/*!*/ MakeArray0() {

            return new RubyArray(0);

        }



        [Emitted]

        public static RubyArray/*!*/ MakeArray1(object item1) {

            RubyArray result = new RubyArray(1);

            result.Add(item1);

            return result;

        }



        [Emitted]

        public static RubyArray/*!*/ MakeArray2(object item1, object item2) {

            RubyArray result = new RubyArray(2);

            result.Add(item1);

            result.Add(item2);

            return result;

        }



        [Emitted]

        public static RubyArray/*!*/ MakeArray3(object item1, object item2, object item3) {

            RubyArray result = new RubyArray(3);

            result.Add(item1);

            result.Add(item2);

            result.Add(item3);

            return result;

        }



        [Emitted]

        public static RubyArray/*!*/ MakeArray4(object item1, object item2, object item3, object item4) {

            RubyArray result = new RubyArray(4);

            result.Add(item1);

            result.Add(item2);

            result.Add(item3);

            result.Add(item4);

            return result;

        }



        [Emitted]

        public static RubyArray/*!*/ MakeArray5(object item1, object item2, object item3, object item4, object item5) {

            RubyArray result = new RubyArray(5);

            result.Add(item1);

            result.Add(item2);

            result.Add(item3);

            result.Add(item4);

            result.Add(item5);

            return result;

        }



        [Emitted]

        public static RubyArray/*!*/ MakeArrayN(object[]/*!*/ items) {

            Debug.Assert(items != null);

            var array = new RubyArray(items.Length);

            array.AddVector(items, 0, items.Length);

            return array;

        }



        #endregion



        #region MakeHash



        [Emitted]

        public static Hash/*!*/ MakeHash0(RubyScope/*!*/ scope) {

            return new Hash(scope.RubyContext.EqualityComparer, 0);

        }

        

        [Emitted]

        public static Hash/*!*/ MakeHash(RubyScope/*!*/ scope, object[]/*!*/ items) {

            return RubyUtils.SetHashElements(scope.RubyContext, new Hash(scope.RubyContext.EqualityComparer, items.Length / 2), items);

        }



        #endregion



        #region Array



        [Emitted]

        public static RubyArray/*!*/ AddRange(RubyArray/*!*/ array, IList/*!*/ list) {

            return array.AddRange(list);

        }



        [Emitted] // method call:

        public static RubyArray/*!*/ AddSubRange(RubyArray/*!*/ result, IList/*!*/ array, int start, int count) {

            return result.AddRange(array, start, count);

        }



        [Emitted]

        public static RubyArray/*!*/ AddItem(RubyArray/*!*/ array, object item) {

            array.Add(item);

            return array;

        }



        [Emitted]

        public static IList/*!*/ SplatAppend(IList/*!*/ array, IList/*!*/ list) {

            Utils.AddRange(array, list);

            return array;

        }



        [Emitted]

        public static object Splat(IList/*!*/ list) {

            if (list.Count <= 1) {

                return (list.Count > 0) ? list[0] : null;

            }



            return list;

        }



        // 1.8 behavior

        [Emitted]

        public static object SplatPair(object value, IList/*!*/ list) {

            if (list.Count == 0) {

                return value;

            }



            RubyArray result = new RubyArray(list.Count + 1);

            result.Add(value);

            result.AddRange(list);

            return result;

        }



        [Emitted]

        public static IList/*!*/ Unsplat(object splattee) {

            var list = splattee as IList;

            if (list == null) {

                list = new RubyArray(1);

                list.Add(splattee);

            }

            return list;

        }



        // CaseExpression

        [Emitted]

        public static bool ExistsUnsplatCompare(CallSite<Func<CallSite, object, object, object>>/*!*/ comparisonSite, object splattee, object value) {

            var list = splattee as IList;

            if (list != null) {

                for (int i = 0; i < list.Count; i++) {

                    if (IsTrue(comparisonSite.Target(comparisonSite, list[i], value))) {

                        return true;

                    }

                }

                return false;

            } else {

                return IsTrue(comparisonSite.Target(comparisonSite, splattee, value)); 

            }

        }



        // CaseExpression

        [Emitted]

        public static bool ExistsUnsplat(object splattee) {

            var list = splattee as IList;

            if (list != null) {

                for (int i = 0; i < list.Count; i++) {

                    if (IsTrue(list[i])) {

                        return true;

                    }

                }

                return false;

            } else {

                return IsTrue(splattee);

            }

        }



        [Emitted] // parallel assignment:

        public static object GetArrayItem(IList/*!*/ array, int index) {

            Debug.Assert(index >= 0);

            return index < array.Count ? array[index] : null;

        }



        [Emitted] // parallel assignment:

        public static object GetTrailingArrayItem(IList/*!*/ array, int index, int explicitCount) {

            Debug.Assert(index >= 0);

            int i = Math.Max(array.Count, explicitCount) - index;

            return i >= 0 ? array[i] : null;

        }



        [Emitted] // parallel assignment:

        public static RubyArray/*!*/ GetArrayRange(IList/*!*/ array, int startIndex, int explicitCount) {

            int size = array.Count - explicitCount;

            if (size > 0) {

                RubyArray result = new RubyArray(size);

                for (int i = 0; i < size; i++) {

                    result.Add(array[startIndex + i]);

                }

                return result;

            } else {

                return new RubyArray();

            }

        }



        #endregion



        #region CLR Vectors (factories mimic Ruby Array factories)



        [Emitted, RubyConstructor]

        public static object/*!*/ CreateVector<TElement>(

            ConversionStorage<TElement>/*!*/ elementConversion, 

            ConversionStorage<Union<IList, int>>/*!*/ toAryToInt, 

            BlockParam block, RubyClass/*!*/ self, [NotNull]object/*!*/ arrayOrSize) {



            Debug.Assert(typeof(TElement) == self.GetUnderlyingSystemType().GetElementType());



            var site = toAryToInt.GetSite(CompositeConversionAction.Make(self.Context, CompositeConversion.ToAryToInt));

            var union = site.Target(site, arrayOrSize);



            if (union.First != null) {

                // block ignored

                return CreateVectorInternal(elementConversion, union.First);

            } else if (block != null) {

                return PopulateVector(elementConversion, CreateVectorInternal<TElement>(union.Second), block);

            } else {

                return CreateVectorInternal<TElement>(union.Second);

            }

        }



        [Emitted, RubyConstructor]

        public static Array/*!*/ CreateVectorWithValues<TElement>(ConversionStorage<TElement>/*!*/ elementConversion,

            RubyClass/*!*/ self, [DefaultProtocol]int size, [DefaultProtocol]TElement value) {

            Debug.Assert(typeof(TElement) == self.GetUnderlyingSystemType().GetElementType());



            TElement[] result = CreateVectorInternal<TElement>(size);

            for (int i = 0; i < result.Length; i++) {

                result[i] = value;

            }

            return result;

        }



        private static TElement[]/*!*/ CreateVectorInternal<TElement>(int size) {

            if (size < 0) {

                throw RubyExceptions.CreateArgumentError("negative array size");

            }



            return new TElement[size];

        }



        private static Array/*!*/ CreateVectorInternal<TElement>(ConversionStorage<TElement>/*!*/ elementConversion, IList/*!*/ list) {

            var site = elementConversion.GetDefaultConversionSite();



            var result = new TElement[list.Count];

            for (int i = 0; i < result.Length; i++) {

                object item = list[i];

                result[i] = (item is TElement) ? (TElement)item : site.Target(site, item);

            }



            return result;

        }



        private static object PopulateVector<TElement>(ConversionStorage<TElement>/*!*/ elementConversion, TElement[]/*!*/ array, BlockParam/*!*/ block) {

            var site = elementConversion.GetDefaultConversionSite();



            for (int i = 0; i < array.Length; i++) {

                object item;

                if (block.Yield(i, out item)) {

                    return item;

                }

                array[i] = site.Target(site, item);

            }

            return array;

        }



        #endregion



        #region Global Variables



        [Emitted]

        public static object GetGlobalVariable(RubyScope/*!*/ scope, string/*!*/ name) {

            object value;

            // no error reported if the variable doesn't exist:

            scope.RubyContext.TryGetGlobalVariable(scope, name, out value);

            return value;

        }



        [Emitted]

        public static bool IsDefinedGlobalVariable(RubyScope/*!*/ scope, string/*!*/ name) {

            GlobalVariable variable;

            return scope.RubyContext.TryGetGlobalVariable(name, out variable) && variable.IsDefined;

        }



        [Emitted]

        public static object SetGlobalVariable(object value, RubyScope/*!*/ scope, string/*!*/ name) {

            scope.RubyContext.SetGlobalVariable(scope, name, value);

            return value;

        }



        [Emitted]

        public static void AliasGlobalVariable(RubyScope/*!*/ scope, string/*!*/ newName, string/*!*/ oldName) {

            scope.RubyContext.AliasGlobalVariable(newName, oldName);

        }



        #endregion



        #region DLR Scopes



        internal static bool TryGetGlobalScopeConstant(RubyContext/*!*/ context, Scope/*!*/ scope, string/*!*/ name, out object value) {

            string mangled;

            ScopeStorage scopeStorage = ((object)scope.Storage) as ScopeStorage;

            if (scopeStorage != null) {

                return scopeStorage.TryGetValue(name, false, out value)

                    || (mangled = RubyUtils.TryMangleName(name)) != null && scopeStorage.TryGetValue(mangled, false, out value);

            } else {

                return context.Operations.TryGetMember(scope, name, out value)

                    || (mangled = RubyUtils.TryMangleName(name)) != null && context.Operations.TryGetMember(scope, mangled, out value);

            }

        }



        // TODO:

        internal static void ScopeSetMember(Scope scope, string name, object value) {

            ScopeStorage scopeStorage = ((object)scope.Storage) as ScopeStorage;

            if (scopeStorage != null) {

                scopeStorage.SetValue(name, false, value);

                return;

            }



            throw new NotImplementedException();

        }



        // TODO:

        internal static bool ScopeContainsMember(Scope scope, string name) {

            ScopeStorage scopeStorage = ((object)scope.Storage) as ScopeStorage;

            if (scopeStorage != null) {

                return scopeStorage.HasValue(name, false);

            }



            throw new NotImplementedException();

        }



        // TODO:

        internal static bool ScopeDeleteMember(Scope scope, string name) {

            ScopeStorage scopeStorage = ((object)scope.Storage) as ScopeStorage;

            if (scopeStorage != null) {

                return scopeStorage.DeleteValue(name, false);

            }



            throw new NotImplementedException();

        }



        // TODO:

        internal static IList<KeyValuePair<string, object>> ScopeGetItems(Scope scope) {

            ScopeStorage scopeStorage = ((object)scope.Storage) as ScopeStorage;

            if (scopeStorage != null) {

                return scopeStorage.GetItems();

            }



            throw new NotImplementedException();

        }



        #endregion



        #region Regex



        [Emitted] //RegexMatchReference:

        public static MutableString GetCurrentMatchGroup(RubyScope/*!*/ scope, int index) {

            Debug.Assert(index >= 0);

            return scope.GetInnerMostClosureScope().GetCurrentMatchGroup(index);

        }



        [Emitted] //RegexMatchReference:

        public static MatchData GetCurrentMatchData(RubyScope/*!*/ scope) {

            return scope.GetInnerMostClosureScope().CurrentMatch;

        }



        [Emitted] //RegexMatchReference:

        public static MutableString GetCurrentMatchLastGroup(RubyScope/*!*/ scope) {

            return scope.GetInnerMostClosureScope().GetCurrentMatchLastGroup();

        }



        [Emitted] //RegexMatchReference:

        public static MutableString GetCurrentPreMatch(RubyScope/*!*/ scope) {

            return scope.GetInnerMostClosureScope().GetCurrentPreMatch();

        }



        [Emitted] //RegexMatchReference:

        public static MutableString GetCurrentPostMatch(RubyScope/*!*/ scope) {

            return scope.GetInnerMostClosureScope().GetCurrentPostMatch();

        }



        [Emitted] //RegularExpression:

        public static bool MatchLastInputLine(RubyRegex/*!*/ regex, RubyScope/*!*/ scope) {

            var str = scope.GetInnerMostClosureScope().LastInputLine as MutableString;

            return (str != null) ? RubyRegex.SetCurrentMatchData(scope, regex, str) != null : false;

        }



        [Emitted] //MatchExpression:

        public static object MatchString(MutableString str, RubyRegex/*!*/ regex, RubyScope/*!*/ scope) {

            var match = RubyRegex.SetCurrentMatchData(scope, regex, str);

            return (match != null) ? ScriptingRuntimeHelpers.Int32ToObject(match.Index) : null;

        }



        #endregion



        public const char SuffixLiteral = 'L';       // Repr: literal string

        public const char SuffixMutable = 'M';       // non-literal "...#{expr}..."



        /// <summary>

        /// Specialized signatures exist for upto the following number of string parts

        /// </summary>

        public const int MakeStringParamCount = 2;



        #region CreateRegex



        private static RubyRegex/*!*/ CreateRegexWorker(

            RubyRegexOptions options, 

            StrongBox<RubyRegex> regexpCache, 

            bool isLiteralWithoutSubstitutions,

            Func<RubyRegex> createRegex) {



            try {

                bool once = ((options & RubyRegexOptions.Once) == RubyRegexOptions.Once) || isLiteralWithoutSubstitutions;

                if (once) {

                    // Note that the user is responsible for thread synchronization

                    if (regexpCache.Value == null) {

                        regexpCache.Value = createRegex();

                    }

                    return regexpCache.Value;

                } else {

                    // In the future, we can consider caching the last Regexp. For some regexp literals 

                    // with substitution, the substition will be the same most of the time

                    return createRegex();

                }

            } catch (RegexpError e) {

                if (isLiteralWithoutSubstitutions) {

                    // Ideally, this should be thrown during parsing of the source, even if the 

                    // expression happens to be unreachable at runtime.

                    throw new SyntaxError(e.Message);

                } else {

                    throw;

                }

            }

        }



        [Emitted]

        public static RubyRegex/*!*/ CreateRegexB(byte[]/*!*/ bytes, RubyEncoding/*!*/ encoding, RubyRegexOptions options, StrongBox<RubyRegex> regexpCache) {

            Func<RubyRegex> createRegex = delegate { return new RubyRegex(CreateMutableStringB(bytes, encoding), options); };

            return CreateRegexWorker(options, regexpCache, true, createRegex);

        }



        [Emitted]

        public static RubyRegex/*!*/ CreateRegexL(string/*!*/ str1, RubyEncoding/*!*/ encoding, RubyRegexOptions options, StrongBox<RubyRegex> regexpCache) {

            Func<RubyRegex> createRegex = delegate { return new RubyRegex(CreateMutableStringL(str1, encoding), options); };

            return CreateRegexWorker(options, regexpCache, true, createRegex);

        }

        

        [Emitted]

        public static RubyRegex/*!*/ CreateRegexM(MutableString str1, RubyEncoding/*!*/ encoding, RubyRegexOptions options, StrongBox<RubyRegex> regexpCache) {

            Func<RubyRegex> createRegex = delegate { return new RubyRegex(CreateMutableStringM(str1, encoding), options); };

            return CreateRegexWorker(options, regexpCache, false, createRegex);

        }



        [Emitted]

        public static RubyRegex/*!*/ CreateRegexLM(string/*!*/ str1, MutableString str2, RubyEncoding/*!*/ encoding, RubyRegexOptions options, StrongBox<RubyRegex> regexpCache) {

            Func<RubyRegex> createRegex = delegate { return new RubyRegex(CreateMutableStringLM(str1, str2, encoding), options); };

            return CreateRegexWorker(options, regexpCache, false, createRegex);

        }



        [Emitted]

        public static RubyRegex/*!*/ CreateRegexML(MutableString str1, string/*!*/ str2, RubyEncoding/*!*/ encoding, RubyRegexOptions options, StrongBox<RubyRegex> regexpCache) {

            Func<RubyRegex> createRegex = delegate { return new RubyRegex(CreateMutableStringML(str1, str2, encoding), options); };

            return CreateRegexWorker(options, regexpCache, false, createRegex);

        }



        [Emitted]

        public static RubyRegex/*!*/ CreateRegexMM(MutableString str1, MutableString str2, RubyEncoding/*!*/ encoding, RubyRegexOptions options, StrongBox<RubyRegex> regexpCache) {

            Func<RubyRegex> createRegex = delegate { return new RubyRegex(CreateMutableStringMM(str1, str2, encoding), options); };

            return CreateRegexWorker(options, regexpCache, false, createRegex);

        }



        [Emitted]

        public static RubyRegex/*!*/ CreateRegexN(MutableString[]/*!*/ strings, RubyRegexOptions options, StrongBox<RubyRegex> regexpCache) {

            Func<RubyRegex> createRegex = delegate { return new RubyRegex(CreateMutableStringN(strings), options); };

            return CreateRegexWorker(options, regexpCache, false, createRegex);

        }



        #endregion



        #region CreateMutableString



        [Emitted]

        public static MutableString/*!*/ CreateMutableStringB(byte[]/*!*/ bytes, RubyEncoding/*!*/ encoding) {

            return MutableString.CreateBinary(bytes, encoding);

        }



        [Emitted]

        public static MutableString/*!*/ CreateMutableStringL(string/*!*/ str1, RubyEncoding/*!*/ encoding) {

            return MutableString.Create(str1, encoding);

        }



        [Emitted]

        public static MutableString/*!*/ CreateMutableStringM(MutableString str1, RubyEncoding/*!*/ encoding) {

            return MutableString.CreateInternal(str1, encoding);

        }



        [Emitted]

        public static MutableString/*!*/ CreateMutableStringLM(string/*!*/ str1, MutableString str2, RubyEncoding/*!*/ encoding) {

            return MutableString.CreateMutable(str1, encoding).Append(str2);

        }



        [Emitted]

        public static MutableString/*!*/ CreateMutableStringML(MutableString str1, string/*!*/ str2, RubyEncoding/*!*/ encoding) {

            return MutableString.CreateInternal(str1, encoding).Append(str2);

        }



        [Emitted]

        public static MutableString/*!*/ CreateMutableStringMM(MutableString str1, MutableString str2, RubyEncoding/*!*/ encoding) {

            return MutableString.CreateInternal(str1, encoding).Append(str2);

        }



        // TODO: we should emit Append calls directly, and not create an array first

        [Emitted]

        public static MutableString/*!*/ CreateMutableStringN(MutableString/*!*/[]/*!*/ parts) {

            Debug.Assert(parts.Length > 0);

            var result = MutableString.CreateMutable(RubyEncoding.Ascii);



            for (int i = 0; i < parts.Length; i++) {

                result.Append(parts[i]);

            }



            return result;

        }



        #endregion



        #region CreateSymbol



        [Emitted]

        public static RubySymbol/*!*/ CreateSymbolM(MutableString str1, RubyEncoding/*!*/ encoding, RubyScope/*!*/ scope) {

            return scope.RubyContext.CreateSymbol(CreateMutableStringM(str1, encoding), false);

        }



        [Emitted]

        public static RubySymbol/*!*/ CreateSymbolLM(string/*!*/ str1, MutableString str2, RubyEncoding/*!*/ encoding, RubyScope/*!*/ scope) {

            return scope.RubyContext.CreateSymbol(CreateMutableStringLM(str1, str2, encoding), false);

        }



        [Emitted]

        public static RubySymbol/*!*/ CreateSymbolML(MutableString str1, string/*!*/ str2, RubyEncoding/*!*/ encoding, RubyScope/*!*/ scope) {

            return scope.RubyContext.CreateSymbol(CreateMutableStringML(str1, str2, encoding), false);

        }

        

        [Emitted]

        public static RubySymbol/*!*/ CreateSymbolMM(MutableString str1, MutableString str2, RubyEncoding/*!*/ encoding, RubyScope/*!*/ scope) {

            return scope.RubyContext.CreateSymbol(CreateMutableStringMM(str1, str2, encoding), false);

        }



        [Emitted]

        public static RubySymbol/*!*/ CreateSymbolN(MutableString[]/*!*/ strings, RubyScope/*!*/ scope) {

            return scope.RubyContext.CreateSymbol(CreateMutableStringN(strings), false);

        }



        #endregion



        #region Strings, Encodings



        [Emitted]

        public static RubyEncoding/*!*/ CreateEncoding(int codepage) {

            return RubyEncoding.GetRubyEncoding(codepage);

        }



        [Emitted, Obsolete("Internal only")]

        public static byte[]/*!*/ GetMutableStringBytes(MutableString/*!*/ str) {



            int byteCount;

            var result = str.GetByteArray(out byteCount);

            return result;

        }



        #endregion



        #region Booleans



        [Emitted]

        public static bool IsTrue(object obj) {

            return (obj is bool) ? (bool)obj == true : obj != null;

        }



        [Emitted]

        public static bool IsFalse(object obj) {

            return (obj is bool) ? (bool)obj == false : obj == null;

        }



        [Emitted]

        public static object NullIfFalse(object obj) {

            return (obj is bool && !(bool)obj) ? null : obj;

        }



        [Emitted]

        public static object NullIfTrue(object obj) {

            return (obj is bool && !(bool)obj || obj == null) ? DefaultArgument : null;

        }



        #endregion



        #region Exceptions



        //

        // NOTE:

        // Exception Ops go directly to the current exception object. MRI ignores potential aliases.

        //



        /// <summary>

        /// Called in try-filter that wraps the entire body of a block. 

        /// We just need to capture stack trace, should not filter out any exception.

        /// </summary>

        [Emitted]

        public static bool FilterBlockException(RubyScope/*!*/ scope, Exception/*!*/ exception) {

            RubyExceptionData.GetInstance(exception).CaptureExceptionTrace(scope);

            return false;

        }



        /// <summary>

        /// Called in try-filter that wraps the entire top-level code. 

        /// We just need to capture stack trace, should not filter out any exception.

        /// </summary>

        [Emitted]

        public static bool TraceTopLevelCodeFrame(RubyScope/*!*/ scope, Exception/*!*/ exception) {

            RubyExceptionData.GetInstance(exception).CaptureExceptionTrace(scope);

            return false;

        }



        // Ruby method exit filter:

        [Emitted]

        public static bool IsMethodUnwinderTargetFrame(RubyScope/*!*/ scope, Exception/*!*/ exception) {

            var unwinder = exception as MethodUnwinder;

            if (unwinder == null) {

                RubyExceptionData.GetInstance(exception).CaptureExceptionTrace(scope);

                return false;

            } else {

                return unwinder.TargetFrame == scope.FlowControlScope;

            }

        }



        [Emitted]

        public static object GetMethodUnwinderReturnValue(Exception/*!*/ exception) {

            return ((MethodUnwinder)exception).ReturnValue;

        }



        [Emitted]

        public static void LeaveMethodFrame(RuntimeFlowControl/*!*/ rfc) {

            rfc.LeaveMethod();

        }

        

        /// <summary>

        /// Filters exceptions raised from EH-body, EH-rescue and EH-else clauses.

        /// </summary>

        [Emitted]

        public static bool CanRescue(RubyScope/*!*/ scope, Exception/*!*/ exception) {

            if (exception is StackUnwinder) {

                return false;

            }



            LocalJumpError lje = exception as LocalJumpError;

            if (lje != null && lje.SkipFrame == scope.FlowControlScope) {

                return false;

            }



            // calls "new" on the exception class if it hasn't been called yet:

            exception = RubyExceptionData.HandleException(scope.RubyContext, exception);



            scope.RubyContext.CurrentException = exception;

            RubyExceptionData.GetInstance(exception).CaptureExceptionTrace(scope);

            return true;

        }



        [Emitted]

        public static Exception/*!*/ MarkException(Exception/*!*/ exception) {

            RubyExceptionData.GetInstance(exception).Handled = true;

            return exception;

        }



        [Emitted]

        public static Exception GetCurrentException(RubyScope/*!*/ scope) {

            return scope.RubyContext.CurrentException;

        }



        /// <summary>

        /// Sets $!. Used in EH finally clauses to restore exception stored in oldExceptionVariable local.

        /// </summary>

        [Emitted] 

        public static void SetCurrentException(RubyScope/*!*/ scope, Exception exception) {

            scope.RubyContext.CurrentException = exception;

        }



        [Emitted] //RescueClause:

        public static bool CompareException(BinaryOpStorage/*!*/ comparisonStorage, RubyScope/*!*/ scope, object classObject) {            

            var context = scope.RubyContext;

            var site = comparisonStorage.GetCallSite("===");

            bool result = IsTrue(site.Target(site, classObject, context.CurrentException));

            if (result) {

                RubyExceptionData.ActiveExceptionHandled(context.CurrentException);

            }

            return result;

        }



        [Emitted] //RescueClause:

        public static bool CompareSplattedExceptions(BinaryOpStorage/*!*/ comparisonStorage, RubyScope/*!*/ scope, IList/*!*/ classObjects) {

            for (int i = 0; i < classObjects.Count; i++) {

                if (CompareException(comparisonStorage, scope, classObjects[i])) {

                    return true;

                }

            }

            return false;

        }



        [Emitted] //RescueClause:

        public static bool CompareDefaultException(RubyScope/*!*/ scope) {

            RubyContext ec = scope.RubyContext;



            // MRI doesn't call === here;

            bool result = ec.IsInstanceOf(ec.CurrentException, ec.StandardErrorClass);

            if (result) {

                RubyExceptionData.ActiveExceptionHandled(ec.CurrentException);

            }

            return result;

        }



        [Emitted]

        public static string/*!*/ GetDefaultExceptionMessage(RubyClass/*!*/ exceptionClass) {

            return exceptionClass.Name;

        }



        [Emitted]

        public static ArgumentException/*!*/ CreateArgumentsError(string message) {

            return (ArgumentException)RubyExceptions.CreateArgumentError(message);

        }



        [Emitted]

        public static ArgumentException/*!*/ CreateArgumentsErrorForMissingBlock() {

            return (ArgumentException)RubyExceptions.CreateArgumentError("block not supplied");

        }



        [Emitted]

        public static ArgumentException/*!*/ CreateArgumentsErrorForProc(string className) {

            return (ArgumentException)RubyExceptions.CreateArgumentError(String.Format("wrong type argument {0} (should be callable)", className));

        }



        [Emitted]

        public static ArgumentException/*!*/ MakeWrongNumberOfArgumentsError(int actual, int expected) {

            return new ArgumentException(String.Format("wrong number of arguments ({0} for {1})", actual, expected));

        }



        [Emitted] //SuperCall

        public static Exception/*!*/ MakeTopLevelSuperException() {

            return new MissingMethodException("super called outside of method");

        }



        [Emitted] //SuperCallAction

        public static Exception/*!*/ MakeMissingSuperException(string/*!*/ name) {

            return new MissingMethodException(String.Format("super: no superclass method `{0}'", name));

        }



        [Emitted]

        public static Exception/*!*/ MakeVirtualClassInstantiatedError() {

            return RubyExceptions.CreateTypeError("can't create instance of virtual class");

        }



        [Emitted]

        public static Exception/*!*/ MakeAbstractMethodCalledError(RuntimeMethodHandle/*!*/ method) {

            return new NotImplementedException(String.Format("Abstract method `{0}' not implemented", MethodInfo.GetMethodFromHandle(method)));

        }



        [Emitted]

        public static Exception/*!*/ MakeInvalidArgumentTypesError(string/*!*/ methodName) {

            // TODO:

            return new ArgumentException(String.Format("wrong number or type of arguments for `{0}'", methodName));

        }



        [Emitted]

        public static Exception/*!*/ MakeTypeConversionError(RubyContext/*!*/ context, object value, Type/*!*/ type) {

            return RubyExceptions.CreateTypeConversionError(context.GetClassDisplayName(value), context.GetTypeName(type, true));

        }



        [Emitted]

        public static Exception/*!*/ MakeAmbiguousMatchError(string/*!*/ message) {

            // TODO:

            return new AmbiguousMatchException(message);

        }



        [Emitted]

        public static Exception/*!*/ MakeAllocatorUndefinedError(RubyClass/*!*/ classObj) {

            return RubyExceptions.CreateAllocatorUndefinedError(classObj);

        }



        [Emitted]

        public static Exception/*!*/ MakeNotClrTypeError(RubyClass/*!*/ classObj) {

            return RubyExceptions.CreateNotClrTypeError(classObj);

        }



        [Emitted]

        public static Exception/*!*/ MakeConstructorUndefinedError(RubyClass/*!*/ classObj) {

            return RubyExceptions.CreateTypeError(String.Format("`{0}' doesn't have a visible CLR constructor", 

                classObj.Context.GetTypeName(classObj.TypeTracker.Type, true)

            ));

        }



        [Emitted]

        public static Exception/*!*/ MakeMissingDefaultConstructorError(RubyClass/*!*/ classObj, string/*!*/ initializerOwnerName) {

            return RubyExceptions.CreateMissingDefaultConstructorError(classObj, initializerOwnerName);

        }



        [Emitted]

        public static Exception/*!*/ MakePrivateMethodCalledError(RubyContext/*!*/ context, object target, string/*!*/ methodName) {

            return RubyExceptions.CreatePrivateMethodCalled(context, target, methodName);

        }



        [Emitted]

        public static Exception/*!*/ MakeProtectedMethodCalledError(RubyContext/*!*/ context, object target, string/*!*/ methodName) {

            return RubyExceptions.CreateProtectedMethodCalled(context, target, methodName);

        }



        [Emitted]

        public static Exception/*!*/ MakeClrProtectedMethodCalledError(RubyContext/*!*/ context, object target, string/*!*/ methodName) {

            return new MissingMethodException(

                RubyExceptions.FormatMethodMissingMessage(context, target, methodName, "CLR protected method `{0}' called for {1}; " +

                "CLR protected methods can only be called with a receiver whose class is a Ruby subclass of the class declaring the method")

            );

        }



        [Emitted]

        public static Exception/*!*/ MakeClrVirtualMethodCalledError(RubyContext/*!*/ context, object target, string/*!*/ methodName) {

            return new MissingMethodException(

                RubyExceptions.FormatMethodMissingMessage(context, target, methodName, "Virtual CLR method `{0}' called via super from {1}; " +

                "Super calls to virtual CLR methods can only be used in a Ruby subclass of the class declaring the method")

            );

        }



        [Emitted]

        public static Exception/*!*/ MakeImplicitSuperInBlockMethodError() {

            return RubyExceptions.CreateRuntimeError("implicit argument passing of super from method defined by define_method() is not supported. Specify all arguments explicitly.");

        }



        [Emitted]

        public static Exception/*!*/ MakeMissingMethodError(RubyContext/*!*/ context, object self, string/*!*/ methodName) {

            return RubyExceptions.CreateMethodMissing(context, self, methodName);

        }



        [Emitted]

        public static Exception/*!*/ MakeMissingMemberError(string/*!*/ memberName) {

            return new MissingMemberException(String.Format(CultureInfo.InvariantCulture, "undefined member: `{0}'", memberName));

        }



        #endregion



        #region Ranges



        [Emitted]

        public static Range/*!*/ CreateInclusiveRange(object begin, object end, RubyScope/*!*/ scope, BinaryOpStorage/*!*/ comparisonStorage) {

            return new Range(comparisonStorage, scope.RubyContext, begin, end, false);

        }



        [Emitted]

        public static Range/*!*/ CreateExclusiveRange(object begin, object end, RubyScope/*!*/ scope, BinaryOpStorage/*!*/ comparisonStorage) {

            return new Range(comparisonStorage, scope.RubyContext, begin, end, true);

        }



        [Emitted]

        public static Range/*!*/ CreateInclusiveIntegerRange(int begin, int end) {

            return new Range(begin, end, false);

        }



        [Emitted]

        public static Range/*!*/ CreateExclusiveIntegerRange(int begin, int end) {

            return new Range(begin, end, true);

        }



        #endregion



        #region Dynamic Operations



        // allocator for struct instances:

        [Emitted]

        public static RubyStruct/*!*/ AllocateStructInstance(RubyClass/*!*/ self) {

            return RubyStruct.Create(self);

        }



        // factory for struct instances:

        [Emitted]

        public static RubyStruct/*!*/ CreateStructInstance(RubyClass/*!*/ self, [NotNull]params object[]/*!*/ items) {

            var result = RubyStruct.Create(self);

            result.SetValues(items);

            return result;

        }



        [Emitted]

        public static DynamicMetaObject/*!*/ GetMetaObject(IRubyObject/*!*/ obj, MSA.Expression/*!*/ parameter) {

            return new RubyObject.Meta(parameter, BindingRestrictions.Empty, obj);

        }



        [Emitted]

        public static RubyMethod/*!*/ CreateBoundMember(object target, RubyMemberInfo/*!*/ info, string/*!*/ name) {

            return new RubyMethod(target, info, name);

        }



        [Emitted]

        public static RubyMethod/*!*/ CreateBoundMissingMember(object target, RubyMemberInfo/*!*/ info, string/*!*/ name) {

            return new RubyMethod.Curried(target, info, name);

        }



        [Emitted]

        public static bool IsClrSingletonRuleValid(RubyContext/*!*/ context, object/*!*/ target, int expectedVersion) {

            RubyInstanceData data;

            RubyClass immediate;



            // TODO: optimize this (we can have a hashtable of singletons per class: Weak(object) => Struct { ImmediateClass, InstanceVariables, Flags }):

            return context.TryGetClrTypeInstanceData(target, out data) && (immediate = data.ImmediateClass) != null && immediate.IsSingletonClass

                && immediate.Version.Method == expectedVersion;

        }



        [Emitted]

        public static bool IsClrNonSingletonRuleValid(RubyContext/*!*/ context, object/*!*/ target, VersionHandle/*!*/ versionHandle, int expectedVersion) {

            RubyInstanceData data;

            RubyClass immediate;



            return versionHandle.Method == expectedVersion

                // TODO: optimize this (we can have a hashtable of singletons per class: Weak(object) => Struct { ImmediateClass, InstanceVariables, Flags }):

                && !(context.TryGetClrTypeInstanceData(target, out data) && (immediate = data.ImmediateClass) != null && immediate.IsSingletonClass);

        }



        // super call condition

        [Emitted]

        public static object GetSuperCallTarget(RubyScope/*!*/ scope, int targetId) {

            while (true) {

                switch (scope.Kind) {

                    case ScopeKind.Method:

                        return targetId == 0 ? scope.SelfObject : NeedsUpdate;



                    case ScopeKind.BlockMethod:

                        return targetId == ((RubyBlockScope)scope).BlockFlowControl.Proc.Method.Id ? scope.SelfObject : NeedsUpdate;



                    case ScopeKind.TopLevel:

                        // This method is only called if there was method or block-method scope in lexical scope chain.

                        // Once there is it cannot be undone. It can only be shadowed by a block scope that became block-method scope, or

                        // a block-method scope's target-id can be changed.

                        throw Assert.Unreachable;

                }



                scope = scope.Parent;

            }

        }



        // super call condition

        [Emitted]

        public static bool IsSuperOutOfMethodScope(RubyScope/*!*/ scope) {

            while (true) {

                switch (scope.Kind) {

                    case ScopeKind.Method:

                    case ScopeKind.BlockMethod:

                        return false;



                    case ScopeKind.TopLevel:

                        return true;

                }



                scope = scope.Parent;

            }

        }



        #endregion



        #region Conversions



        [Emitted] // ProtocolConversionAction

        public static Proc/*!*/ ToProcValidator(string/*!*/ className, object obj) {

            Proc result = obj as Proc;

            if (result == null) {

                throw RubyExceptions.CreateReturnTypeError(className, "to_proc", "Proc");

            }

            return result;

        }



        // Used for implicit conversions from System.String to MutableString (to_str conversion like).

        [Emitted]

        public static MutableString/*!*/ StringToMutableString(string/*!*/ str) {

            return MutableString.Create(str, RubyEncoding.UTF8);

        }



        // Used for implicit conversions from System.Object to MutableString (to_s conversion like).

        [Emitted]

        public static MutableString/*!*/ ObjectToMutableString(object/*!*/ value) {

            return (value != null) ? MutableString.Create(value.ToString(), RubyEncoding.UTF8) : MutableString.FrozenEmpty;

        }



        [Emitted] // ProtocolConversionAction

        public static MutableString/*!*/ ToStringValidator(string/*!*/ className, object obj) {

            MutableString result = obj as MutableString;

            if (result == null) {

                throw RubyExceptions.CreateReturnTypeError(className, "to_str", "String");

            }

            return result;

        }



        [Emitted] // ProtocolConversionAction

        public static string/*!*/ ToSymbolValidator(string/*!*/ className, object obj) {

            var str = obj as MutableString;

            if (str == null) {

                throw RubyExceptions.CreateReturnTypeError(className, "to_str", "String"); 

            }

            return str.ConvertToString();

        }



        [Emitted] // ProtocolConversionAction

        public static string/*!*/ ConvertSymbolToClrString(RubySymbol/*!*/ value) {

            return value.ToString();

        }



        [Emitted] // ProtocolConversionAction

        public static string/*!*/ ConvertRubySymbolToClrString(RubyContext/*!*/ context, int value) {

            context.ReportWarning("do not use Fixnums as Symbols");



            RubySymbol result = context.FindSymbol(value);

            if (result != null) {

                return result.ToString();

            } else {

                throw RubyExceptions.CreateArgumentError(String.Format("{0} is not a symbol", value));

            }

        }



        [Emitted] // ProtocolConversionAction

        public static string/*!*/ ConvertMutableStringToClrString(MutableString/*!*/ value) {

            return value.ConvertToString();

        }



        [Emitted] // ProtocolConversionAction

        public static MutableString/*!*/ ConvertSymbolToMutableString(RubySymbol/*!*/ value) {

            // TODO: this is used for DefaultProtocol conversions; we might avoid clonning in some (many?) cases

            return value.String.Clone();

        }

        

        [Emitted] // ProtocolConversionAction

        public static RubyRegex/*!*/ ToRegexValidator(string/*!*/ className, object obj) {

            return new RubyRegex(RubyRegex.Escape(ToStringValidator(className, obj)), RubyRegexOptions.NONE);

        }



        [Emitted] // ProtocolConversionAction

        public static IList/*!*/ ToArrayValidator(string/*!*/ className, object obj) {

            var result = obj as IList;

            if (result == null) {

                throw RubyExceptions.CreateReturnTypeError(className, "to_ary", "Array");

            }

            return result;

        }



        [Emitted] // ProtocolConversionAction

        public static IList/*!*/ ToAValidator(string/*!*/ className, object obj) {

            var result = obj as IList;

            if (result == null) {

                throw RubyExceptions.CreateReturnTypeError(className, "to_a", "Array");

            }

            return result;

        }



        [Emitted] // ProtocolConversionAction

        public static IDictionary<object, object>/*!*/ ToHashValidator(string/*!*/ className, object obj) {

            var result = obj as IDictionary<object, object>;

            if (result == null) {

                throw RubyExceptions.CreateReturnTypeError(className, "to_hash", "Hash");

            }

            return result;

        }



        private static int ToIntValidator(string/*!*/ className, string/*!*/ targetType, object obj) {

            if (obj is int) {

                return (int)obj;

            }



            var bignum = obj as BigInteger;

            if ((object)bignum != null) {

                int fixnum;

                if (bignum.AsInt32(out fixnum)) {

                    return fixnum;

                }

                throw RubyExceptions.CreateRangeError("bignum too big to convert into {0}", targetType);

            }



            throw RubyExceptions.CreateReturnTypeError(className, "to_int", "Integer");

        }



        [Emitted] // ProtocolConversionAction

        public static int ToFixnumValidator(string/*!*/ className, object obj) {

            return ToIntValidator(className, "Fixnum", obj);

        }



        [Emitted] // ProtocolConversionAction

        public static Byte ToByteValidator(string/*!*/ className, object obj) {

            return Converter.ToByte(ToIntValidator(className, "System::Byte", obj));

        }



        [Emitted] // ProtocolConversionAction

        public static SByte ToSByteValidator(string/*!*/ className, object obj) {

            return Converter.ToSByte(ToIntValidator(className, "System::SByte", obj));

        }



        [Emitted] // ProtocolConversionAction

        public static Int16 ToInt16Validator(string/*!*/ className, object obj) {

            return Converter.ToInt16(ToIntValidator(className, "System::Int16", obj));

        }



        [Emitted] // ProtocolConversionAction

        public static UInt16 ToUInt16Validator(string/*!*/ className, object obj) {

            return Converter.ToUInt16(ToIntValidator(className, "System::UInt16", obj));

        }



        [Emitted] // ProtocolConversionAction

        public static UInt32 ToUInt32Validator(string/*!*/ className, object obj) {

            if (obj is int) {

                return Converter.ToUInt32((int)obj);

            }



            var bignum = obj as BigInteger;

            if ((object)bignum != null) {

                return Converter.ToUInt32(bignum);

            }



            throw RubyExceptions.CreateReturnTypeError(className, "to_int/to_i", "Integer");

        }



        [Emitted] // ProtocolConversionAction

        public static Int64 ToInt64Validator(string/*!*/ className, object obj) {

            if (obj is int) {

                return (int)obj;

            }



            var bignum = obj as BigInteger;

            if ((object)bignum != null) {

                return Converter.ToInt64(bignum);

            }



            throw RubyExceptions.CreateReturnTypeError(className, "to_int/to_i", "Integer");

        }



        [Emitted] // ProtocolConversionAction

        public static UInt64 ToUInt64Validator(string/*!*/ className, object obj) {

            if (obj is int) {

                return Converter.ToUInt64((int)obj);

            }



            var bignum = obj as BigInteger;

            if ((object)bignum != null) {

                return Converter.ToUInt64(bignum);

            }



            throw RubyExceptions.CreateReturnTypeError(className, "to_int/to_i", "Integer");

        }



        [Emitted] // ProtocolConversionAction

        public static BigInteger ToBignumValidator(string/*!*/ className, object obj) {

            if (obj is int) {

                return (int)obj;

            }



            var bignum = obj as BigInteger;

            if ((object)bignum != null) {

                return bignum;

            }



            throw RubyExceptions.CreateReturnTypeError(className, "to_int/to_i", "Integer");

        }



        [Emitted] // ProtocolConversionAction

        public static IntegerValue ToIntegerValidator(string/*!*/ className, object obj) {

            if (obj is int) {

                return new IntegerValue((int)obj);

            }



            var bignum = obj as BigInteger;

            if ((object)bignum != null) {

                return new IntegerValue(bignum);

            }



            throw RubyExceptions.CreateReturnTypeError(className, "to_int/to_i", "Integer");

        }



        [Emitted] // ProtocolConversionAction

        public static double ToDoubleValidator(string/*!*/ className, object obj) {

            if (obj is double) {

                return (double)obj;

            }



            if (obj is float) {

                return (double)(float)obj;

            }



            throw RubyExceptions.CreateReturnTypeError(className, "to_f", "Float");

        }



        [Emitted] // ProtocolConversionAction

        public static float ToSingleValidator(string/*!*/ className, object obj) {

            if (obj is double) {

                return (float)(double)obj;

            }



            if (obj is float) {

                return (float)obj;

            }



            throw RubyExceptions.CreateReturnTypeError(className, "to_f", "System::Single");

        }



        [Emitted]

        public static double ConvertBignumToFloat(BigInteger/*!*/ value) {

            double result;

            return value.TryToFloat64(out result) ? result : (value.IsNegative() ? Double.NegativeInfinity : Double.PositiveInfinity);

        }



        [Emitted]

        public static double ConvertMutableStringToFloat(RubyContext/*!*/ context, MutableString/*!*/ value) {

            return ConvertStringToFloat(context, value.ConvertToString());

        }



        [Emitted]

        public static double ConvertStringToFloat(RubyContext/*!*/ context, string/*!*/ value) {

            double result;

            bool complete;

            if (Tokenizer.TryParseDouble(value, out result, out complete) && complete) {

                return result;

            }



            throw RubyExceptions.InvalidValueForType(context, value, "Float");

        }



        [Emitted] // ProtocolConversionAction

        public static Exception/*!*/ CreateTypeConversionError(string/*!*/ fromType, string/*!*/ toType) {

            return RubyExceptions.CreateTypeConversionError(fromType, toType);

        }



        [Emitted] // ConvertToFixnumAction

        public static int ConvertBignumToFixnum(BigInteger/*!*/ bignum) {

            int fixnum;

            if (bignum.AsInt32(out fixnum)) {

                return fixnum;

            }

            throw RubyExceptions.CreateRangeError("bignum too big to convert into Fixnum");

        }



        [Emitted] // ConvertDoubleToFixnum

        public static int ConvertDoubleToFixnum(double value) {

            try {

                return checked((int)value);

            } catch (OverflowException) {

                throw RubyExceptions.CreateRangeError(String.Format("float {0} out of range of Fixnum", value));

            }

        }



        [Emitted] // ConvertToSAction

        public static MutableString/*!*/ ToSDefaultConversion(RubyContext/*!*/ context, object target, object converted) {

            return converted as MutableString ?? RubyUtils.ObjectToMutableString(context, target);

        }



        #endregion

        

        #region Instance variable support



        [Emitted]

        public static object GetInstanceVariable(RubyScope/*!*/ scope, object self, string/*!*/ name) {

            RubyInstanceData data = scope.RubyContext.TryGetInstanceData(self);

            return (data != null) ? data.GetInstanceVariable(name) : null;

        }



        [Emitted]

        public static bool IsDefinedInstanceVariable(RubyScope/*!*/ scope, object self, string/*!*/ name) {

            RubyInstanceData data = scope.RubyContext.TryGetInstanceData(self);

            if (data == null) return false;

            object value;

            return data.TryGetInstanceVariable(name, out value);

        }



        [Emitted]

        public static object SetInstanceVariable(object self, object value, RubyScope/*!*/ scope, string/*!*/ name) {

            scope.RubyContext.SetInstanceVariable(self, name, value);

            return value;

        }



        #endregion



        #region Class Variables



        [Emitted]

        public static object GetClassVariable(RubyScope/*!*/ scope, string/*!*/ name) {

            // owner is the first module in scope:

            RubyModule owner = scope.GetInnerMostModuleForClassVariableLookup();

            return GetClassVariableInternal(owner, name);

        }



        private static object GetClassVariableInternal(RubyModule/*!*/ module, string/*!*/ name) {

            object value;

            if (module.TryResolveClassVariable(name, out value) == null) {

                throw RubyExceptions.CreateNameError(String.Format("uninitialized class variable {0} in {1}", name, module.Name));

            }

            return value;

        }



        [Emitted]

        public static object TryGetClassVariable(RubyScope/*!*/ scope, string/*!*/ name) {

            object value;

            // owner is the first module in scope:

            scope.GetInnerMostModuleForClassVariableLookup().TryResolveClassVariable(name, out value);

            return value;

        }



        [Emitted]

        public static bool IsDefinedClassVariable(RubyScope/*!*/ scope, string/*!*/ name) {

            // owner is the first module in scope:

            RubyModule owner = scope.GetInnerMostModuleForClassVariableLookup();

            object value;

            return owner.TryResolveClassVariable(name, out value) != null;

        }



        [Emitted]

        public static object SetClassVariable(object value, RubyScope/*!*/ scope, string/*!*/ name) {

            return SetClassVariableInternal(scope.GetInnerMostModuleForClassVariableLookup(), name, value);

        }



        private static object SetClassVariableInternal(RubyModule/*!*/ lexicalOwner, string/*!*/ name, object value) {

            object oldValue;

            RubyModule owner = lexicalOwner.TryResolveClassVariable(name, out oldValue);

            (owner ?? lexicalOwner).SetClassVariable(name, value);

            return value;

        }



        #endregion



        #region Ruby Types



        [Emitted]

        public static string/*!*/ ObjectToString(IRubyObject/*!*/ obj) {

            return RubyUtils.ObjectToMutableString(obj).ToString();

        }



        [Emitted] //RubyTypeBuilder

        public static RubyInstanceData/*!*/ GetInstanceData(ref RubyInstanceData/*!*/ instanceData) {

            if (instanceData == null) {

                Interlocked.CompareExchange(ref instanceData, new RubyInstanceData(), null);

            }

            return instanceData;

        }



        [Emitted]

        public static bool IsObjectFrozen(RubyInstanceData instanceData) {

            return instanceData != null && instanceData.IsFrozen;

        }



        [Emitted]

        public static bool IsObjectTainted(RubyInstanceData instanceData) {

            return instanceData != null && instanceData.IsTainted;

        }



        [Emitted]

        public static bool IsObjectUntrusted(RubyInstanceData instanceData) {

            return instanceData != null && instanceData.IsUntrusted;

        }



        [Emitted]

        public static void FreezeObject(ref RubyInstanceData instanceData) {

            RubyOps.GetInstanceData(ref instanceData).Freeze();

        }



        [Emitted]

        public static void SetObjectTaint(ref RubyInstanceData instanceData, bool value) {

            RubyOps.GetInstanceData(ref instanceData).IsTainted = value;

        }



        [Emitted]

        public static void SetObjectTrustiness(ref RubyInstanceData instanceData, bool untrusted) {

            RubyOps.GetInstanceData(ref instanceData).IsUntrusted = untrusted;

        }



#if !SILVERLIGHT // serialization

        [Emitted(UseReflection = true)] //RubyTypeBuilder

        public static void DeserializeObject(out RubyInstanceData/*!*/ instanceData, out RubyClass/*!*/ immediateClass, SerializationInfo/*!*/ info) {

            immediateClass = (RubyClass)info.GetValue(RubyUtils.SerializationInfoClassKey, typeof(RubyClass));

            RubyInstanceData newInstanceData = null;

            foreach (SerializationEntry entry in info) {

                if (entry.Name.StartsWith("@", StringComparison.Ordinal)) {

                    if (newInstanceData == null) {

                        newInstanceData = new RubyInstanceData();

                    }

                    newInstanceData.SetInstanceVariable(entry.Name, entry.Value);

                }

            }

            instanceData = newInstanceData;

        }



        [Emitted(UseReflection = true)] //RubyTypeBuilder

        public static void SerializeObject(RubyInstanceData instanceData, RubyClass/*!*/ immediateClass, SerializationInfo/*!*/ info) {

            info.AddValue(RubyUtils.SerializationInfoClassKey, immediateClass, typeof(RubyClass));

            if (instanceData != null) {

                string[] instanceNames = instanceData.GetInstanceVariableNames();

                foreach (string name in instanceNames) {

                    object value;

                    if (!instanceData.TryGetInstanceVariable(name, out value)) {

                        value = null;

                    }

                    info.AddValue(name, value, typeof(object));

                }

            }

        }

#endif

        #endregion



        #region Delegates, Events



        /// <summary>

        /// Hooks up an event to call a proc at hand.

        /// EventInfo is passed in as object since it is an internal type.

        /// </summary>

        [Emitted]

        public static Proc/*!*/ HookupEvent(RubyEventInfo/*!*/ eventInfo, object/*!*/ target, Proc/*!*/ proc) {

            eventInfo.Tracker.AddHandler(target, proc, eventInfo.Context.DelegateCreator);

            return proc;

        }



        [Emitted]

        public static RubyEvent/*!*/ CreateEvent(RubyEventInfo/*!*/ eventInfo, object/*!*/ target, string/*!*/ name) {

            return new RubyEvent(target, eventInfo, name);

        }



        [Emitted]

        public static Delegate/*!*/ CreateDelegateFromProc(Type/*!*/ type, Proc proc) {

            if (proc == null) {

                throw RubyExceptions.NoBlockGiven();

            }

            BlockParam bp = CreateBfcForProcCall(proc);

            return proc.LocalScope.RubyContext.DelegateCreator.GetDelegate(bp, type);

        }



        [Emitted]

        public static Delegate/*!*/ CreateDelegateFromMethod(Type/*!*/ type, RubyMethod/*!*/ method) {

            return method.Info.Context.DelegateCreator.GetDelegate(method, type);

        }



        #endregion



        #region Tuples



        // Instance variable storages needs MT<n> to be a subclass of MT<m> for all n > m.

        // This property is not true if we used DynamicNull as a generic argument for arities that are not powers of 2 like MutableTuple.MakeTupleType does.

        // We make this property true for all simple tuples, thus instance variable storages can only use tuples of size <= 128.

        internal static Type/*!*/ MakeObjectTupleType(int fieldCount) {

            if (fieldCount <= MutableTuple.MaxSize) {

                if (fieldCount <= 1) {

                    return typeof(MutableTuple<object>);

                } else if (fieldCount <= 2) {

                    return typeof(MutableTuple<object, object>);

                } else if (fieldCount <= 4) {

                    return typeof(MutableTuple<object, object, object, object>);

                } else if (fieldCount <= 8) {

                    return typeof(MutableTuple<object, object, object, object, object, object, object, object>);

                } else if (fieldCount <= 16) {

                    return typeof(MutableTuple<object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object>);

                } else if (fieldCount <= 32) {

                    return typeof(MutableTuple<object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object>);

                } else if (fieldCount <= 64) {

                    return typeof(MutableTuple<object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object>);

                } else {

                    return typeof(MutableTuple<object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object>);

                }

            }



            Type[] types = new Type[fieldCount];

            for (int i = 0; i < types.Length; i++) {

                types[i] = typeof(object);

            }

            return MutableTuple.MakeTupleType(types);

        }



        internal static MutableTuple/*!*/ CreateObjectTuple(int fieldCount) {

            Debug.Assert(fieldCount <= MutableTuple.MaxSize);

            if (fieldCount <= 1) {

                return new MutableTuple<object>();

            } else if (fieldCount <= 2) {

                return new MutableTuple<object, object>();

            } else if (fieldCount <= 4) {

                return new MutableTuple<object, object, object, object>();

            } else if (fieldCount <= 8) {

                return new MutableTuple<object, object, object, object, object, object, object, object>();

            } else if (fieldCount <= 16) {

                return new MutableTuple<object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object>();

            } else if (fieldCount <= 32) {

                return new MutableTuple<object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object>();

            } else if (fieldCount <= 64) {

                return new MutableTuple<object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object>();

            } else {

                return new MutableTuple<object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object>();

            }

        }

        #endregion



        [Emitted]

        public static void X(string marker) {

        }

        

        [Emitted]

        public static object CreateDefaultInstance() {

            // nop (stub)

            return null;

        }

    }

}