/IronPython_Main/Runtime/Microsoft.Dynamic/Actions/Calls/ReturnReferenceArgBuilder.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 

 * dlr@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 System.Linq.Expressions;

#else

using Microsoft.Scripting.Ast;

#endif



using System;

using System.Collections.Generic;

using System.Dynamic;

using System.Reflection;



namespace Microsoft.Scripting.Actions.Calls {

    using Ast = Expression;



    /// <summary>

    /// Builds a parameter for a reference argument when a StrongBox has not been provided.  The

    /// updated return value is returned as one of the resulting return values.

    /// </summary>

    internal sealed class ReturnReferenceArgBuilder : SimpleArgBuilder {

        private ParameterExpression _tmp;



        public ReturnReferenceArgBuilder(ParameterInfo info, int index)

            : base(info, info.ParameterType.GetElementType(), index, false, false) {

        }



        protected override SimpleArgBuilder Copy(int newIndex) {

            return new ReturnReferenceArgBuilder(ParameterInfo, newIndex);

        }



        public override ArgBuilder Clone(ParameterInfo newType) {

            return new ReturnReferenceArgBuilder(newType, Index);

        }



        internal protected override Expression ToExpression(OverloadResolver resolver, RestrictedArguments args, bool[] hasBeenUsed) {

            if (_tmp == null) {

                _tmp = resolver.GetTemporary(Type, "outParam");

            }



            return Ast.Block(Ast.Assign(_tmp, base.ToExpression(resolver, args, hasBeenUsed)), _tmp);

        }



        internal override Expression ToReturnExpression(OverloadResolver resolver) {

            return _tmp;

        }



        internal override Expression ByRefArgument {

            get { return _tmp; }

        }



        public override int Priority {

            get {

                return 5;

            }

        }

    }

}