/IronPython_2_0/Src/Microsoft.Scripting.Core/Ast/DoStatement.cs

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

 *

 * Copyright (c) Microsoft Corporation. 

 *

 * This source code is subject to terms and conditions of the Microsoft Public License. A 

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

 * you cannot locate the  Microsoft Public License, 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 Microsoft Public License.

 *

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

 *

 *

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

using System; using Microsoft;





using Microsoft.Scripting.Utils;



namespace Microsoft.Linq.Expressions {



    // TODO: rename to DoWhileExpression

    public sealed class DoStatement : Expression {

        private readonly Expression _test;

        private readonly Expression _body;

        private readonly LabelTarget _break;

        private readonly LabelTarget _continue;



        internal DoStatement(Expression body, Expression test, LabelTarget @break, LabelTarget @continue, Annotations annotations)

            : base(ExpressionType.DoStatement, typeof(void), annotations) {

            _test = test;

            _body = body;

            _break = @break;

            _continue = @continue;

        }



        public Expression Test {

            get { return _test; }

        }



        public Expression Body {

            get { return _body; }

        }



        public LabelTarget BreakLabel {

            get { return _break; }

        }



        public LabelTarget ContinueLabel {

            get { return _continue; }

        }



        internal override Expression Accept(ExpressionTreeVisitor visitor) {

            return visitor.VisitDoWhile(this);

        }

    }



    public partial class Expression {

        public static DoStatement DoWhile(Expression body, Expression test) {

            return DoWhile(body, test, null, null, null);

        }

        public static DoStatement DoWhile(Expression body, Expression test, LabelTarget @break, LabelTarget @continue) {

            return DoWhile(body, test, @break, @continue, null);

        }

        public static DoStatement DoWhile(Expression body, Expression test, LabelTarget @break, LabelTarget @continue, Annotations annotations) {

            RequiresCanRead(body, "body");

            RequiresCanRead(test, "test");

            ContractUtils.Requires(test.Type == typeof(bool), "test", Strings.ConditionMustBeBoolean);

            // TODO: lift the restriction on break, and allow loops to have non-void type

            ContractUtils.Requires(@break == null || @break.Type == typeof(void), "break", Strings.LabelTypeMustBeVoid);

            ContractUtils.Requires(@continue == null || @continue.Type == typeof(void), "continue", Strings.LabelTypeMustBeVoid);

            return new DoStatement(body, test, @break, @continue, annotations);

        }

    }

}