/IronPython_Main/Runtime/Microsoft.Dynamic/Ast/SkipInterpretExpression.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;



namespace Microsoft.Scripting.Ast {



    /// <summary>

    /// We don't need to insert code to track lines in adaptive mode as the

    /// interpreter does that for us. TODO: improve the adaptive compiler so we

    /// don't need to do this, and can just remove line tracking from languages

    /// </summary>

    public sealed class SkipInterpretExpression : Expression {

        private readonly Expression _body;



        internal SkipInterpretExpression(Expression body) {

            if (body.Type != typeof(void)) {

                body = Expression.Block(body, Utils.Empty());

            }

            _body = body;

        }



        public Expression Body {

            get { return _body; }

        }



        public sealed override Type Type {

            get { return typeof(void); }

        }



        public sealed override ExpressionType NodeType {

            get { return ExpressionType.Extension; }

        }



        public override bool CanReduce {

            get { return true;  }

        }



        public override Expression Reduce() {

            return _body;

        }



        protected override Expression VisitChildren(ExpressionVisitor visitor) {

            Expression body = visitor.Visit(_body);

            if (body == _body) {

                return this;

            }

            return new SkipInterpretExpression(body);

        }

    }



    public static partial class Utils {

        public static SkipInterpretExpression SkipInterpret(Expression body) {

            var skip = body as SkipInterpretExpression;

            if (skip != null) {

                return skip;

            }

            return new SkipInterpretExpression(body);

        }

    }

}