ConstantVisitor.cs

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// 
//  Copyright 2010-2015 Deveel
// 
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
// 
//        http://www.apache.org/licenses/LICENSE-2.0
// 
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//

using System;

using Deveel.Data.Sql.Objects;
using Deveel.Data.Types;

namespace Deveel.Data.Sql.Expressions {
    class ConstantVisitor : SqlExpressionVisitor {
        public ConstantVisitor() {
            IsConstant = true;
        }

        public bool IsConstant { get; private set; }

        public override SqlExpression VisitConstant(SqlConstantExpression constant) {
            var value = constant.Value;
            if (value.Type.TypeCode == SqlTypeCode.Array) {
                var array = value.Value as SqlArray;
                if (array != null && !array.IsNull) {
                    foreach (var exp in array) {
                        if (!exp.IsConstant()) {
                            IsConstant = false;
                            break;
                        }
                    }
                }
            }

            return base.VisitConstant(constant);
        }

        public override SqlExpression VisitReference(SqlReferenceExpression reference) {
            IsConstant = false;
            return base.VisitReference(reference);
        }

        public override SqlExpression VisitVariableReference(SqlVariableReferenceExpression reference) {
            IsConstant = false;
            return base.VisitVariableReference(reference);
        }

        public override SqlExpression VisitFunctionCall(SqlFunctionCallExpression expression) {
            return base.VisitFunctionCall(expression);
        }

        public override SqlExpression VisitQuery(SqlQueryExpression query) {
            return base.VisitQuery(query);
        }
    }
}