/IronPython_Main/Languages/IronPython/IronPython/Compiler/Ast/AndExpression.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 MSAst = System.Linq.Expressions;

#else

using MSAst = Microsoft.Scripting.Ast;

#endif



using System;

using IronPython.Runtime.Binding;

using Microsoft.Scripting.Actions;

using Microsoft.Scripting.Utils;

using AstUtils = Microsoft.Scripting.Ast.Utils;



namespace IronPython.Compiler.Ast {

    using Ast = MSAst.Expression;



    public class AndExpression : Expression {

        private readonly Expression _left, _right;



        public AndExpression(Expression left, Expression right) {

            ContractUtils.RequiresNotNull(left, "left");

            ContractUtils.RequiresNotNull(right, "right");



            _left = left;

            _right = right;

            StartIndex = left.StartIndex;

            EndIndex = right.EndIndex;

        }



        public Expression Left {

            get { return _left; }

        }



        public Expression Right {

            get { return _right; }

        } 



        public override MSAst.Expression Reduce() {

            MSAst.Expression left = _left;

            MSAst.Expression right = _right;



            Type t = Type;

            MSAst.ParameterExpression tmp = Ast.Variable(t, "__all__");



            return Ast.Block(

                new [] { tmp },

                Ast.Condition(

                    GlobalParent.Convert(

                        typeof(bool),

                        ConversionResultKind.ExplicitCast,

                        Ast.Assign(

                            tmp,

                            AstUtils.Convert(

                                left,

                                t

                            )

                        )

                    ),

                    AstUtils.Convert(

                        right,

                        t

                    ),

                    tmp

                )

            );

        }



        public override Type Type {

            get {

                return _left.Type == _right.Type ? _left.Type : typeof(object);

            }

        }



        public override void Walk(PythonWalker walker) {

            if (walker.Walk(this)) {

                if (_left != null) {

                    _left.Walk(walker);

                }

                if (_right != null) {

                    _right.Walk(walker);

                }

            }

            walker.PostWalk(this);

        }



        internal override bool CanThrow {

            get {

                return _left.CanThrow || _right.CanThrow;

            }

        }

    }

}