ReturnTypeVisitor.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;
using Deveel.Data.Routines;
using Deveel.Data.Types;

namespace Deveel.Data.Sql.Expressions {
    class ReturnTypeVisitor : SqlExpressionVisitor {
        private readonly IRequest query;
        private readonly IVariableResolver variableResolver;

        private SqlType sqlType;

        public ReturnTypeVisitor(IRequest query, IVariableResolver variableResolver) {
            this.query = query;
            this.variableResolver = variableResolver;

            sqlType = PrimitiveTypes.Null();
        }

        public override SqlExpression VisitBinary(SqlBinaryExpression binaryEpression) {
            switch (binaryEpression.ExpressionType) {
                case SqlExpressionType.Add:
                case SqlExpressionType.Subtract:
                case SqlExpressionType.Multiply:
                case SqlExpressionType.Modulo:
                case SqlExpressionType.Divide:
                    sqlType = PrimitiveTypes.Numeric();
                    break;
                default:
                    // we assume the expression type is already been check to be binary.
                    sqlType = PrimitiveTypes.Boolean();
                    break;

            }
            
            return base.VisitBinary(binaryEpression);
        }

        public override SqlExpression VisitConstant(SqlConstantExpression constant) {
            sqlType = constant.Value.Type;

            return base.VisitConstant(constant);
        }

        public override SqlExpression VisitFunctionCall(SqlFunctionCallExpression expression) {
            var invoke = new Invoke(expression.FunctioName, expression.Arguments);
            var function = invoke.ResolveRoutine(query) as IFunction;
            if (function != null)
                sqlType = function.ReturnType(invoke, query, variableResolver);

            return base.VisitFunctionCall(expression);
        }

        public override SqlExpression VisitReference(SqlReferenceExpression reference) {
            var name = reference.ReferenceName;
            sqlType = variableResolver.ReturnType(name);

            return base.VisitReference(reference);
        }

        public override SqlExpression Visit(SqlExpression expression) {
            if (expression is QueryReferenceExpression)
                return VisitQueryReference((QueryReferenceExpression) expression);

            return base.Visit(expression);
        }

        private SqlExpression VisitQueryReference(QueryReferenceExpression expression) {
            sqlType = expression.QueryReference.ReturnType;
            return expression;
        }

        public SqlType GetType(SqlExpression expression) {
            Visit(expression);
            return sqlType;
        }
    }
}