SqlCaseExpressionNode.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 SqlCaseExpressionNode : SqlNode, IExpressionNode {
        internal SqlCaseExpressionNode() {
        }

        public IEnumerable<CaseSwitchNode> CaseSwitches { get; private set; }

        public IExpressionNode ElseExpression { get; private set; }

        public IExpressionNode TestExpression { get; private set; }

        protected override ISqlNode OnChildNode(ISqlNode node) {
            if (node.NodeName == "case_test_expression_opt") {
                if (node.ChildNodes.Any()) {
                    var exp = node.ChildNodes.First();
                    if (exp is IExpressionNode)
                        TestExpression = (IExpressionNode) exp;
                }
            } else if (node.NodeName == "case_when_then_list") {
                GetWhenThenList(node);
            } else if (node.NodeName == "case_else_opt") {
                GetElse(node);
            }

            return base.OnChildNode(node);
        }

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

        private void GetWhenThenList(ISqlNode node) {
            var switches = new List<CaseSwitchNode>();

            foreach (var childNode in node.ChildNodes) {
                if (childNode is CaseSwitchNode)
                    switches.Add((CaseSwitchNode)childNode);
            }

            CaseSwitches = switches.ToArray();
        }
    }
}