VirtualTable.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.Tables {
    class VirtualTable : JoinedTable {
        private IList<int>[] rowList;
        private int rowCount;

        public VirtualTable(IEnumerable<ITable> tables) 
            : this(tables, null) {
        }

        public VirtualTable(IEnumerable<ITable> tables, IList<IList<int>> rows) 
            : base(tables) {
            SetRows(rows);
        }

        public VirtualTable(ITable table) 
            : this(table, null) {
        }

        public VirtualTable(ITable table, IList<int> rows) 
            : base(table) {
            SetRows(new []{rows});
        }

        private void SetRows(IList<IList<int>> rows) {
            var tableList = ReferenceTables.ToList();

            for (int i = 0; i < tableList.Count; ++i) {
                rowList[i] = new List<int>(rows[i]);
            }
            if (rows.Count > 0) {
                rowCount = rows[0].Count();
            }
        }

        protected override void Init(IEnumerable<ITable> tables) {
            var tableList = tables.ToList();
            base.Init(tableList);

            int tableCount = tableList.Count;
            rowList = new IList<int>[tableCount];
            for (int i = 0; i < tableCount; ++i) {
                rowList[i] = new List<int>();
            }
        }

        public override int RowCount {
            get { return rowCount; }
        }

        protected IList<int>[] ReferenceRows {
            get { return rowList; }
        }

        protected override IEnumerable<int> ResolveRowsForTable(IEnumerable<int> rows, int tableNum) {
            var rowSet = rows.ToList();
            IList<int> curRowList = rowList[tableNum];
            for (int n = rowSet.Count - 1; n >= 0; --n) {
                int aa = rowSet[n];
                int bb = curRowList[aa];
                rowSet[n] = bb;
            }

            return rowSet.ToArray();
        }
    }
}