SelectStatementNode.cs

Go to the documentation of this file.

// 
//  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 System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;

using Deveel.Data.Sql.Expressions;
using Deveel.Data.Sql.Statements;

namespace Deveel.Data.Sql.Parser {
    class SelectStatementNode : SqlStatementNode {
        public SqlQueryExpressionNode QueryExpression { get; private set; }

        public IEnumerable<OrderByNode> OrderBy { get; private set; }

        public LimitNode Limit { get; private set; }

        protected override ISqlNode OnChildNode(ISqlNode node) {
            if (node.NodeName == "sql_query_expression") {
                QueryExpression = node as SqlQueryExpressionNode;
            } else if (node.NodeName == "order_opt") {
                GetOrderBy(node);
            } else if (node.NodeName == "limit_opt") {
                GetLimit(node);
            }

            return base.OnChildNode(node);
        }

        private void GetOrderBy(ISqlNode node) {
            var listNode =  node.FindByName("sorted_def_list");
            if (listNode != null) {
                OrderBy = listNode.ChildNodes.Cast<OrderByNode>();
            }
        }

        private void GetLimit(ISqlNode node) {
            var child = node.ChildNodes.FirstOrDefault();
            if (child != null)
                Limit = (LimitNode) child;
        }

        protected override void BuildStatement(StatementBuilder builder) {
            var queryExpression = (SqlQueryExpression) ExpressionBuilder.Build(QueryExpression);
            if (QueryExpression.IntoClause != null) {
                var refExp = ExpressionBuilder.Build(QueryExpression.IntoClause);
                builder.Statements.Add(new SelectIntoStatement(queryExpression, refExp));
            } else {
                var orderBy = BuildOrderBy(OrderBy);
                var statement = new SelectStatement(queryExpression, orderBy);
                statement.Limit = BuildLimit(Limit);
                builder.Statements.Add(statement);
            }
        }

        private IEnumerable<SortColumn> BuildOrderBy(IEnumerable<OrderByNode> nodes) {
            if (nodes == null)
                return null;

            return nodes.Select(node => new SortColumn(ExpressionBuilder.Build(node.Expression), node.Ascending));
        }

        private QueryLimit BuildLimit(LimitNode node) {
            if (node == null)
                return null;

            return new QueryLimit(node.Offset, node.Count);
        }
    }
}