SqlQueryExpressionNode.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 System.Collections.Generic;
using System.Linq;

namespace Deveel.Data.Sql.Parser {
    class SqlQueryExpressionNode : SqlNode, IExpressionNode {
        internal SqlQueryExpressionNode() {
        }

        public bool IsAll { get; private set; }

        public bool IsDistinct { get; private set; }

        public SqlReferenceExpressionNode IntoClause { get; private set; }

        public IEnumerable<SelectItemNode> SelectItems { get; private set; }

        public FromClauseNode FromClause { get; private set; }

        public IExpressionNode WhereExpression { get; private set; }

        public GroupByNode GroupBy { get; private set; }

        public QueryCompositeNode Composite { get; private set; }

        protected override ISqlNode OnChildNode(ISqlNode node) {
            if (node.NodeName == "select_restrict_opt") {
                GetRestrict(node);
            } else if (node.NodeName == "select_set") {
                GetSelectSet(node);
            } else if (node.NodeName == "from_clause_opt") {
                var clause = node.ChildNodes.FirstOrDefault();
                if (clause != null)
                    FromClause = (FromClauseNode) clause;
            } else if (node.NodeName == "where_clause_opt") {
                GetWhereClause(node);
            } else if (node.NodeName == "group_by_opt") {
                GroupBy = node.ChildNodes.FirstOrDefault() as GroupByNode;
            } else if (node.NodeName == "query_composite_opt") {
                var composite = node.ChildNodes.FirstOrDefault();
                if (composite != null)
                    Composite = (QueryCompositeNode) composite;
            } else if (node.NodeName == "select_into_opt") {
                // TODO:
            }

            return base.OnChildNode(node);
        }

        private void GetWhereClause(ISqlNode node) {
            foreach (var childNode in node.ChildNodes) {
                if (childNode is IExpressionNode) {
                    WhereExpression = childNode as IExpressionNode;
                    break;
                }
            }
        }

        private void GetRestrict(ISqlNode node) {
            foreach (var childNode in node.ChildNodes) {
                if (childNode is SqlKeyNode) {
                    var value = ((SqlKeyNode) childNode).Text;
                    if (value == "ALL") {
                        IsAll = true;
                    } else if (value == "DISTINCT") {
                        IsDistinct = true;
                    }
                }
            }
        }

        private void GetSelectSet(ISqlNode node) {
            foreach (var childNode in node.ChildNodes) {
                if (childNode is SqlKeyNode &&
                    ((SqlKeyNode) childNode).Text == "*") {
                    IsAll = true;
                } else if (childNode.NodeName == "select_item_list") {
                    GetSelectItems(childNode);
                }
            }
        }

        private void GetSelectItems(ISqlNode node) {
            var items = new List<SelectItemNode>();
            foreach (var childNode in node.ChildNodes) {
                if (childNode is SelectItemNode)
                    items.Add((SelectItemNode)childNode);
            }

            SelectItems = items.ToArray();
        }
    }
}