/// <summary>
        /// Generates CIL for the statement.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Generate code for the start of the statement.
            var statementLocals = new StatementLocals();
            GenerateStartOfStatement(generator, optimizationInfo, statementLocals);

            // Create the scope.
            this.Scope.GenerateScopeCreation(generator, optimizationInfo);

            // Make sure the scope is reverted even if an exception is thrown.
            generator.BeginExceptionBlock();

            // Setting the InsideTryCatchOrFinally flag converts BR instructions into LEAVE
            // instructions so that the finally block is executed correctly.
            var previousInsideTryCatchOrFinally = optimizationInfo.InsideTryCatchOrFinally;
            optimizationInfo.InsideTryCatchOrFinally = true;

            // Generate code for the body statements.
            this.Body.GenerateCode(generator, optimizationInfo);

            // Reset the InsideTryCatchOrFinally flag.
            optimizationInfo.InsideTryCatchOrFinally = previousInsideTryCatchOrFinally;

            // Revert the scope.
            generator.BeginFinallyBlock();
            this.Scope.GenerateScopeDestruction(generator, optimizationInfo);
            generator.EndExceptionBlock();

            // Generate code for the end of the statement.
            GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
        }

        /// <summary>
        /// Generates CIL for the expression.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // This code is only used for untagged template literals.
            // Tagged template literals are handled by FunctionCallExpression.

            // Load the values array onto the stack.
            generator.LoadInt32(this.Strings.Count + this.Values.Count);
            generator.NewArray(typeof(string));
            for (int i = 0; i < this.Strings.Count; i++)
            {
                // Operands for StoreArrayElement() are: an array (string[]), index (int), value (string).

                // Store the string.
                generator.Duplicate();
                generator.LoadInt32(i * 2);
                generator.LoadString(this.Strings[i]);
                generator.StoreArrayElement(typeof(string));

                if (i == this.Strings.Count - 1)
                    break;

                // Store the value.
                generator.Duplicate();
                generator.LoadInt32(i * 2 + 1);
                this.Values[i].GenerateCode(generator, optimizationInfo);
                EmitConversion.ToString(generator, this.Values[i].ResultType);
                generator.StoreArrayElement(typeof(string));
            }

            // Call String.Concat(string[])
            generator.CallStatic(ReflectionHelpers.String_Concat);
        }

        /// <summary>
        /// Generates CIL for the statement.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Generate code for the start of the statement.
            var statementLocals = new StatementLocals();
            GenerateStartOfStatement(generator, optimizationInfo, statementLocals);

            if (this.ContributesToEvalResult == true && optimizationInfo.EvalResult != null)
            {
                // Emit the expression.
                this.Expression.GenerateCode(generator, optimizationInfo);

                // Store the result.
                EmitConversion.ToAny(generator, this.Expression.ResultType);
                generator.StoreVariable(optimizationInfo.EvalResult);
            }
            else
            {
                // Emit the expression.
                this.Expression.GenerateCode(generator, optimizationInfo);
                generator.Pop();
            }

            // Generate code for the end of the statement.
            GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
        }

        /// <summary>
        /// Generates IL for the script.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        protected override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Declare a variable to store the eval result.
            optimizationInfo.EvalResult = generator.DeclareVariable(typeof(object));

            if (this.StrictMode == true)
            {
                // Create a new scope.
                this.InitialScope.GenerateScopeCreation(generator, optimizationInfo);
            }

            // Verify the scope is correct.
            VerifyScope(generator);

            // Initialize any declarations.
            this.InitialScope.GenerateDeclarations(generator, optimizationInfo);

            // Generate the main body of code.
            this.AbstractSyntaxTree.GenerateCode(generator, optimizationInfo);

            // Make the return value from the method the eval result.
            generator.LoadVariable(optimizationInfo.EvalResult);

            // If the result is null, convert it to undefined.
            var end = generator.CreateLabel();
            generator.Duplicate();
            generator.BranchIfNotNull(end);
            generator.Pop();
            EmitHelpers.EmitUndefined(generator);
            generator.DefineLabelPosition(end);
        }

        /// <summary>
        /// Generates CIL for the statement.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Generate code for the start of the statement.
            var statementLocals = new StatementLocals() { NonDefaultBreakStatementBehavior = true, NonDefaultDebugInfoBehavior = true };
            GenerateStartOfStatement(generator, optimizationInfo, statementLocals);

            // Construct a loop expression.
            // var enumerator = TypeUtilities.EnumeratePropertyNames(rhs).GetEnumerator();
            // while (true) {
            //   continue-target:
            //   if (enumerator.MoveNext() == false)
            //     goto break-target;
            //   lhs = enumerator.Current;
            //
            //   <body statements>
            // }
            // break-target:

            // Call IEnumerable<string> EnumeratePropertyNames(ScriptEngine engine, object obj)
            EmitHelpers.LoadScriptEngine(generator);
            this.TargetObject.GenerateCode(generator, optimizationInfo);
            EmitConversion.ToAny(generator, this.TargetObject.ResultType);
            generator.Call(ReflectionHelpers.TypeUtilities_EnumeratePropertyNames);

            // Call IEnumerable<string>.GetEnumerator()
            generator.Call(ReflectionHelpers.IEnumerable_GetEnumerator);

            // Store the enumerator in a temporary variable.
            var enumerator = generator.CreateTemporaryVariable(typeof(IEnumerator<string>));
            generator.StoreVariable(enumerator);

            var breakTarget = generator.CreateLabel();
            var continueTarget = generator.DefineLabelPosition();

            // Emit debugging information.
            if (optimizationInfo.DebugDocument != null)
                generator.MarkSequencePoint(optimizationInfo.DebugDocument, this.VariableDebugInfo);

            //   if (enumerator.MoveNext() == false)
            //     goto break-target;
            generator.LoadVariable(enumerator);
            generator.Call(ReflectionHelpers.IEnumerator_MoveNext);
            generator.BranchIfFalse(breakTarget);

            // lhs = enumerator.Current;
            generator.LoadVariable(enumerator);
            generator.Call(ReflectionHelpers.IEnumerator_Current);
            this.Variable.GenerateSet(generator, optimizationInfo, PrimitiveType.String, false);

            // Emit the body statement(s).
            optimizationInfo.PushBreakOrContinueInfo(this.Labels, breakTarget, continueTarget, labelledOnly: false);
            this.Body.GenerateCode(generator, optimizationInfo);
            optimizationInfo.PopBreakOrContinueInfo();

            generator.Branch(continueTarget);
            generator.DefineLabelPosition(breakTarget);

            // Generate code for the end of the statement.
            GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
        }

        /// <summary>
        /// Deletes the reference and pushes <c>true</c> if the delete succeeded, or <c>false</c>
        /// if the delete failed.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public void GenerateDelete(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Load the left-hand side and convert to an object instance.
            var lhs = this.GetOperand(0);
            lhs.GenerateCode(generator, optimizationInfo);
            EmitConversion.ToObject(generator, lhs.ResultType);

            // Load the property name and convert to a string.
            var rhs = this.GetOperand(1);
            if (this.OperatorType == OperatorType.MemberAccess && rhs is NameExpression)
                generator.LoadString((rhs as NameExpression).Name);
            else
            {
                rhs.GenerateCode(generator, optimizationInfo);
                EmitConversion.ToString(generator, rhs.ResultType);
            }

            // Call Delete()
            generator.LoadBoolean(optimizationInfo.StrictMode);
            generator.Call(ReflectionHelpers.ObjectInstance_Delete);

            // If the return value is not wanted then pop it from the stack.
            //if (optimizationInfo.SuppressReturnValue == true)
            //    generator.Pop();
        }

 /// <summary>
 /// Emits a default value of the given type.
 /// </summary>
 /// <param name="generator"> The IL generator. </param>
 /// <param name="type"> The type of value to generate. </param>
 public static void EmitDefaultValue(ILGenerator generator, Type type)
 {
     var temp = generator.CreateTemporaryVariable(type);
     generator.LoadAddressOfVariable(temp);
     generator.InitObject(temp.Type);
     generator.LoadVariable(temp);
     generator.ReleaseTemporaryVariable(temp);
 }

 /// <summary>
 /// Emits a JavaScriptException.
 /// </summary>
 /// <param name="generator"> The IL generator. </param>
 /// <param name="name"> The type of error to generate. </param>
 /// <param name="message"> The error message. </param>
 public static void EmitThrow(ILGenerator generator, string name, string message)
 {
     EmitHelpers.LoadScriptEngine(generator);
     generator.LoadString(name);
     generator.LoadString(message);
     generator.NewObject(ReflectionHelpers.JavaScriptException_Constructor_Error);
     generator.Throw();
 }

        /// <summary>
        /// Generates CIL for the expression.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Generate a new method.
            this.context.GenerateCode();

            // Add the generated method to the nested function list.
            if (optimizationInfo.NestedFunctions == null)
                optimizationInfo.NestedFunctions = new List<GeneratedMethod>();
            optimizationInfo.NestedFunctions.Add(this.context.GeneratedMethod);

            // Add all the nested methods to the parent list.
            if (this.context.GeneratedMethod.Dependencies != null)
            {
                foreach (var nestedFunctionExpression in this.context.GeneratedMethod.Dependencies)
                    optimizationInfo.NestedFunctions.Add(nestedFunctionExpression);
            }

            // Store the generated method in the cache.
            long generatedMethodID = GeneratedMethod.Save(this.context.GeneratedMethod);

            // Create a UserDefinedFunction.

            // prototype
            EmitHelpers.LoadScriptEngine(generator);
            generator.Call(ReflectionHelpers.ScriptEngine_Function);
            generator.Call(ReflectionHelpers.FunctionInstance_InstancePrototype);

            // name
            generator.LoadString(this.FunctionName);

            // argumentNames
            generator.LoadInt32(this.ArgumentNames.Count);
            generator.NewArray(typeof(string));
            for (int i = 0; i < this.ArgumentNames.Count; i++)
            {
                generator.Duplicate();
                generator.LoadInt32(i);
                generator.LoadString(this.ArgumentNames[i]);
                generator.StoreArrayElement(typeof(string));
            }

            // scope
            EmitHelpers.LoadScope(generator);

            // bodyText
            generator.LoadString(this.BodyText);

            // body
            generator.LoadInt64(generatedMethodID);
            generator.Call(ReflectionHelpers.GeneratedMethod_Load);


            // strictMode
            generator.LoadBoolean(this.context.StrictMode);

            // new UserDefinedFunction(ObjectInstance prototype, string name, IList<string> argumentNames, DeclarativeScope scope, Func<Scope, object, object[], object> body, bool strictMode)
            generator.NewObject(ReflectionHelpers.UserDefinedFunction_Constructor);
        }

        /// <summary>
        /// Generates CIL for the statement.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Generate code for the start of the statement.
            var statementLocals = new StatementLocals() { NonDefaultSourceSpanBehavior = true };
            GenerateStartOfStatement(generator, optimizationInfo, statementLocals);

            // Generate code for the end of the statement.
            GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
        }

        /// <summary>
        /// Generates CIL for the statement.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Generate code for the start of the statement.
            var statementLocals = new StatementLocals();
            GenerateStartOfStatement(generator, optimizationInfo, statementLocals);

            // Generate code for the end of the statement.
            GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
        }

 /// <summary>
 /// Emits the given value.  Only possible for certain types.
 /// </summary>
 /// <param name="generator"> The IL generator. </param>
 /// <param name="value"> The value to emit. </param>
 public static void EmitValue(ILGenerator generator, object value)
 {
     if (value == null)
         generator.LoadNull();
     else
     {
         switch (Type.GetTypeCode(value.GetType()))
         {
             case TypeCode.Boolean:
                 generator.LoadBoolean((bool)value);
                 break;
             case TypeCode.Byte:
                 generator.LoadInt32((byte)value);
                 break;
             case TypeCode.Char:
                 generator.LoadInt32((char)value);
                 break;
             case TypeCode.Double:
                 generator.LoadDouble((double)value);
                 break;
             case TypeCode.Int16:
                 generator.LoadInt32((short)value);
                 break;
             case TypeCode.Int32:
                 generator.LoadInt32((int)value);
                 break;
             case TypeCode.Int64:
                 generator.LoadInt64((long)value);
                 break;
             case TypeCode.SByte:
                 generator.LoadInt32((sbyte)value);
                 break;
             case TypeCode.Single:
                 generator.LoadDouble((float)value);
                 break;
             case TypeCode.String:
                 generator.LoadString((string)value);
                 break;
             case TypeCode.UInt16:
                 generator.LoadInt32((ushort)value);
                 break;
             case TypeCode.UInt32:
                 generator.LoadInt32((uint)value);
                 break;
             case TypeCode.UInt64:
                 generator.LoadInt64((ulong)value);
                 break;
             case TypeCode.Object:
             case TypeCode.Empty:
             case TypeCode.DateTime:
             case TypeCode.DBNull:
             case TypeCode.Decimal:
                 throw new NotImplementedException(string.Format("Cannot emit the value '{0}'", value));
         }
     }
 }

 /// <summary>
 /// Creates a new LoggingILGenerator instance.
 /// </summary>
 /// <param name="generator"> The ILGenerator that is used to output the IL. </param>
 public LoggingILGenerator(ILGenerator generator)
 {
     if (generator == null)
         throw new ArgumentNullException("generator");
     this.generator = generator;
     this.header = new StringBuilder();
     this.log = new StringBuilder();
     this.definedLabels = new Dictionary<ILLabel, int>();
     this.fixUps = new List<LabelFixUp>();
 }

 /// <summary>
 /// Emits a JavaScriptException.
 /// </summary>
 /// <param name="generator"> The IL generator. </param>
 /// <param name="name"> The type of error to generate. </param>
 /// <param name="message"> The error message. </param>
 /// <param name="path"> The path of the javascript source file that is currently executing. </param>
 /// <param name="function"> The name of the currently executing function. </param>
 /// <param name="line"> The line number of the statement that is currently executing. </param>
 public static void EmitThrow(ILGenerator generator, string name, string message, string path, string function, int line)
 {
     EmitHelpers.LoadScriptEngine(generator);
     generator.LoadString(name);
     generator.LoadString(message);
     generator.LoadInt32(line);
     generator.LoadStringOrNull(path);
     generator.LoadStringOrNull(function);
     generator.NewObject(ReflectionHelpers.JavaScriptException_Constructor_Error);
     generator.Throw();
 }

        /// <summary>
        /// Generates IL for the script.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        protected override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Initialize any function or variable declarations.
            this.InitialScope.GenerateDeclarations(generator, optimizationInfo);

            // Generate code for the source code.
            this.AbstractSyntaxTree.GenerateCode(generator, optimizationInfo);

            // Code in the global context always returns undefined.
            EmitHelpers.EmitUndefined(generator);
        }

        /// <summary>
        /// Pops the value on the stack, converts it to the given type, then pushes the result
        /// onto the stack.
        /// </summary>
        /// <param name="generator"> The IL generator. </param>
        /// <param name="fromType"> The type to convert from. </param>
        /// <param name="toType"> The type to convert to. </param>
        /// <param name="path"> The path of the javascript source file that is currently executing. </param>
        /// <param name="function"> The name of the currently executing function. </param>
        /// <param name="line"> The line number of the statement that is currently executing. </param>
        public static void Convert(ILGenerator generator, PrimitiveType fromType, PrimitiveType toType, string path, string function, int line)
        {
            // Check that a conversion is actually necessary.
            if (fromType == toType)
                return;

            switch (toType)
            {
                case PrimitiveType.Any:
                    ToAny(generator, fromType);
                    break;

                case PrimitiveType.Undefined:
                    generator.Pop();
                    EmitHelpers.EmitUndefined(generator);
                    break;

                case PrimitiveType.Null:
                    generator.Pop();
                    EmitHelpers.EmitNull(generator);
                    break;

                case PrimitiveType.Bool:
                    ToBool(generator, fromType);
                    break;

                case PrimitiveType.Int32:
                    ToInt32(generator, fromType);
                    break;

                case PrimitiveType.UInt32:
                    ToUInt32(generator, fromType);
                    break;

                case PrimitiveType.Number:
                    ToNumber(generator, fromType);
                    break;

                case PrimitiveType.String:
                    ToString(generator, fromType);
                    break;

                case PrimitiveType.ConcatenatedString:
                    ToConcatenatedString(generator, fromType);
                    break;

                case PrimitiveType.Object:
                    ToObject(generator, fromType, path, function, line);
                    break;

                default:
                    throw new NotImplementedException(string.Format("Unsupported primitive type: {0}", toType));
            }
        }

        /// <summary>
        /// Generates CIL for the statement.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Generate code for the start of the statement.
            var statementLocals = new StatementLocals();
            GenerateStartOfStatement(generator, optimizationInfo, statementLocals);

            // Emit an unconditional branch.
            // Note: the continue statement might be branching from inside a try { } or finally { }
            // block to outside.  EmitLongJump() handles this.
            optimizationInfo.EmitLongJump(generator, optimizationInfo.GetContinueTarget(this.Label));

            // Generate code for the end of the statement.
            GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
        }

        /// <summary>
        /// Generates CIL for the end of every statement.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        /// <param name="locals"> Variables common to both GenerateStartOfStatement() and GenerateEndOfStatement(). </param>
        public void GenerateEndOfStatement(ILGenerator generator, OptimizationInfo optimizationInfo, StatementLocals locals)
        {
            if (locals.NonDefaultBreakStatementBehavior == false && this.HasLabels == true)
            {
                // Revert the information needed by the break statement.
                generator.DefineLabelPosition(locals.EndOfStatement);
                optimizationInfo.PopBreakOrContinueInfo();
            }

            #if DEBUG && !SILVERLIGHT && !XBOX
            // Check that the stack count is zero.
            if (generator is DynamicILGenerator && ((DynamicILGenerator)generator).StackSize != locals.OriginalStackSize)
                throw new InvalidOperationException("Encountered unexpected stack imbalance.");
            #endif
        }

        /// <summary>
        /// Generates CIL for the expression.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Get an array of comma-delimited expressions.
            var items = this.Items;

            for (int i = 0; i < items.Count - 1; i++)
            {
                // Generate code for the item, evaluating the side-effects but not producing any values.
                items[i].GenerateCode(generator, optimizationInfo); //.AddFlags(OptimizationFlags.SuppressReturnValue));
                generator.Pop();
            }

            // Generate code for the last item and return the value.
            items[items.Count - 1].GenerateCode(generator, optimizationInfo);
        }

        /// <summary>
        /// Generates CIL for the statement.
        /// </summary>
        /// <param name="generator"> The generator to output the CIL to. </param>
        /// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
        public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
        {
            // Generate code for the start of the statement.
            var statementLocals = new StatementLocals();
            GenerateStartOfStatement(generator, optimizationInfo, statementLocals);

            // Inserts a breakpoint into the IL.
            generator.Breakpoint();

            // When the debugger stops, it stops at the first instruction after the breakpoint.  By
            // inserting a no-op operation the debugger will highlight the "debugger" statement
            // instead of the statement after the "debugger" statement.
            generator.NoOperation();

            // Generate code for the end of the statement.
            GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
        }