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

 *

 * 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 

 * ironruby@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 MSA = System.Linq.Expressions;

#else

using MSA = Microsoft.Scripting.Ast;

#endif



using Microsoft.Scripting;

using Microsoft.Scripting.Utils;

using AstUtils = Microsoft.Scripting.Ast.Utils;



namespace IronRuby.Compiler.Ast {

    using Ast = MSA.Expression;



    /// <summary>

    /// Represents {condition} {and/or/&&/||} {jump-statement}, 

    /// or {condition} ? {jump-statement} : {value}.

    /// </summary>

    public partial class ConditionalJumpExpression : Expression {

        private readonly bool _negateCondition;

        private readonly Expression/*!*/ _condition;

        private readonly Expression _value;

        private readonly JumpStatement/*!*/ _jumpStatement;



        public bool NegateCondition {

            get { return _negateCondition; }

        }



        public bool IsBooleanExpression {

            get { return _value == null; }

        }



        public Expression/*!*/ Condition {

            get { return _condition; }

        }



        public Expression Value {

            get { return _value; }

        }



        public JumpStatement/*!*/ JumpStatement {

            get { return _jumpStatement; }

        }



        public ConditionalJumpExpression(Expression/*!*/ condition, JumpStatement/*!*/ jumpStatement, bool negateCondition, Expression value, SourceSpan location)

            : base(location) {

            ContractUtils.RequiresNotNull(condition, "condition");

            ContractUtils.RequiresNotNull(jumpStatement, "jumpStatement");



            _condition = condition;

            _jumpStatement = jumpStatement;

            _negateCondition = negateCondition;

            _value = value;

        }



        internal override MSA.Expression/*!*/ TransformRead(AstGenerator/*!*/ gen) {

            if (_value != null) {

                return Ast.Block(

                    AstUtils.IfThen(

                        _condition.TransformReadBoolean(gen, !_negateCondition),

                        _jumpStatement.Transform(gen)

                    ),

                    _value.TransformRead(gen)

                );

            } else {

                MSA.Expression tmpVariable = gen.CurrentScope.DefineHiddenVariable("#tmp_cond", typeof(object));

                return Ast.Block(

                    Ast.Assign(tmpVariable, AstUtils.Box(_condition.TransformRead(gen))),

                    AstUtils.IfThen(

                        (_negateCondition ? Methods.IsFalse : Methods.IsTrue).OpCall(tmpVariable),

                        _jumpStatement.Transform(gen)

                    ),

                    tmpVariable

                );

            }

        }

    }

}