RawTableInfo.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 {
    public sealed class RawTableInfo {
        private readonly List<RawTableItem> tableItems;

        public RawTableInfo() {
            tableItems = new List<RawTableItem>();
        }

        private RawTableInfo(IEnumerable<RawTableItem> tableItems)
            : this() {
            this.tableItems.AddRange(tableItems);
        }

        public void Add(IRootTable table, IList<int> rowSet) {
            tableItems.Add(new RawTableItem(table, rowSet));
        }

        public ITable[] GetTables() {
            return tableItems.Select(x => x.Table).Cast<ITable>().ToArray();
        }

        public IList<int>[] GetRows() {
            return tableItems.Select(x => x.Rows).ToArray();
        }

        private RawTableItem[] GetSortedItems() {
            var list = new RawTableItem[tableItems.Count];
            tableItems.CopyTo(list);
            Array.Sort(list);
            return list;
        }

        public RawTableInfo Union(RawTableInfo info) {
            // Number of Table 'columns'

            int colCount = tableItems.Count;

            var merge1 = GetSortedItems();
            var merge2 = info.GetSortedItems();

            int size1 = -1;
            int size2 = -1;

            // First check number of tables in each merge is correct.

            if (merge1.Length != merge2.Length)
                throw new InvalidOperationException("Incorrect format in table union");

            // Check each table in the merge1 set has identical length row_sets

            for (int i = 0; i < merge1.Length; ++i) {
                if (size1 == -1) {
                    size1 = merge1[i].Rows.Count;
                } else {
                    if (size1 != merge1[i].Rows.Count)
                        throw new InvalidOperationException("Incorrect format in table union");
                }
            }

            // Check each table in the merge2 set has identical length row_sets

            for (int i = 0; i < merge2.Length; ++i) {
                // Check the tables in merge2 are identical to the tables in merge1
                if (!merge2[i].Table.TypeEquals(merge1[i].Table))
                    throw new InvalidOperationException("Incorrect format in table union");

                if (size2 == -1) {
                    size2 = merge2[i].Rows.Count;
                } else {
                    if (size2 != merge2[i].Rows.Count)
                        throw new InvalidOperationException("Incorrect format in table union");
                }
            }

            // If size1 or size2 are -1 then we have a corrupt table.  (It will be
            // 0 for an empty table).

            if (size1 == -1 || size2 == -1)
                throw new InvalidOperationException("Incorrect format in table union");

            // We don't need information in 'raw_info' vector anymore so clear it.
            // This may help garbage collection.

            var resultItems = new List<RawTableItem>();

            // Merge the two together into a new list of RawRowElement[]

            int mergeSize = size1 + size2;
            var elems = new RawRowItem[mergeSize];
            int elemsIndex = 0;

            for (int i = 0; i < size1; ++i) {
                var itemRows = new int[colCount];

                for (int n = 0; n < colCount; ++n) {
                    itemRows[n] = merge1[n].Rows[i];
                }

                elems[elemsIndex] = new RawRowItem(itemRows);
                ++elemsIndex;
            }

            for (int i = 0; i < size2; ++i) {
                var itemRows = new int[colCount];

                for (int n = 0; n < colCount; ++n) {
                    itemRows[n] = merge2[n].Rows[i];
                }

                elems[elemsIndex] = new RawRowItem(itemRows);
                ++elemsIndex;
            }

            // Now sort the row elements into order.

            Array.Sort(elems);

            // Remove any duplicate rows.

            for (int i = 0; i < colCount; ++i) {
                merge1[i].Rows.Clear();
            }

            RawRowItem previous = null;
            for (int n = 0; n < mergeSize; ++n) {
                var current = elems[n];

                // Check that the current element in the set is not a duplicate of the
                // previous.

                if (previous == null || previous.CompareTo(current) != 0) {
                    for (int i = 0; i < colCount; ++i) {
                        merge1[i].Rows.Add(current.RowValues[i]);
                    }
                    previous = current;
                }
            }

            for (int i = 0; i < colCount; ++i) {
                resultItems.Add(merge1[i]);
            }

            return new RawTableInfo(resultItems.ToArray());
        }

        public RawTableInfo RemoveDuplicates() {
            // If no tables in duplicate then return

            if (tableItems.Count == 0)
                return new RawTableInfo();

            // Get the length of the first row set in the first table.  We assume that
            // the row set length is identical across each table in the Vector.

            var elen = tableItems[0];
            int len = elen.Rows.Count;
            if (len == 0)
                return new RawTableInfo(tableItems.ToArray());

            // Create a new row element to sort.

            var elems = new RawRowItem[len];
            int width = tableItems.Count;

            // Create an array of RawTableElement so we can quickly access the data

            var rdup = new RawTableItem[width];
            tableItems.CopyTo(rdup);

            // Run through the data building up a new RawTableElement[] array with
            // the information in every raw span.

            for (int i = 0; i < len; ++i) {
                var itemRows = new int[width];
                for (int n = 0; n < width; ++n) {
                    itemRows[n] = rdup[n].Rows[i];
                }
                elems[i] = new RawRowItem(itemRows);
            }

            // Now 'elems' it an array of individual RawRowItem objects which
            // represent each individual row in the table.

            // Now sort and remove duplicates to make up a new set.

            Array.Sort(elems);

            var resultTables = new List<RawTableItem>();

            // Make a new set of RawTableElement[] objects

            var items = rdup;

            // Set up the 'raw_info' vector with the new RawTableElement[] removing
            // any duplicate rows.

            for (int i = 0; i < width; ++i) {
                items[i].Rows.Clear();
            }

            RawRowItem previous = null;
            for (int n = 0; n < len; ++n) {
                var current = elems[n];

                // Check that the current element in the set is not a duplicate of the
                // previous.

                if (previous == null || previous.CompareTo(current) != 0) {
                    for (int i = 0; i < width; ++i) {
                        items[i].Rows.Add(current.RowValues[i]);
                    }
                    previous = current;
                }
            }

            for (int i = 0; i < width; ++i) {
                resultTables.Add(items[i]);
            }

            return new RawTableInfo(resultTables.ToArray());
        }


        #region RawTableItem

        class RawTableItem : IComparable<RawTableItem> {
            public RawTableItem(IRootTable table)
                : this(table, new List<int>()) {
            }

            public RawTableItem(IRootTable table, IList<int> rows) {
                Table = table;
                Rows = new List<int>(rows);
            }

            public IRootTable Table { get; private set; }

            public IList<int> Rows { get; private set; } 

            public int CompareTo(RawTableItem other) {
                return Table.GetHashCode() - other.Table.GetHashCode();
            }
        }

        #endregion

        #region RawRowItem

        class RawRowItem : IComparable<RawRowItem> {
            public RawRowItem(int[] values) {
                RowValues = values;
            }

            public int[] RowValues { get; private set; }

            public int CompareTo(RawRowItem other) {
                int size = RowValues.Length;
                for (int i = 0; i < size; ++i) {
                    int v1 = RowValues[i];
                    int v2 = other.RowValues[i];
                    if (v1 != v2) {
                        return v1 - v2;
                    }
                }
                return 0;
            }
        }

        #endregion
    }
}