RowId.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;

namespace Deveel.Data.Sql.Tables {
    public struct RowId : IEquatable<RowId> {
        public static readonly RowId Null = new RowId(true);

        public RowId(int tableId, int rowNumber) 
            : this(false) {
            RowNumber = rowNumber;
            TableId = tableId;
        }

        private RowId(bool isNull)
            : this() {
            IsNull = isNull;
        }

        public int TableId { get; private set; }

        public int RowNumber { get; private set; }

        public bool IsNull { get; private set; }

        public bool Equals(RowId other) {
            if (IsNull && other.IsNull)
                return true;

            return TableId.Equals(other.TableId) &&
                   RowNumber.Equals(other.RowNumber);
        }

        public override bool Equals(object obj) {
            if (!(obj is RowId))
                return false;

            return Equals((RowId) obj);
        }

        public override int GetHashCode() {
            if (IsNull)
                return 0;

            return unchecked (TableId.GetHashCode() ^ RowNumber.GetHashCode());
        }

        public override string ToString() {
            return String.Format("{0}-{1}", TableId, RowNumber);
        }

        public static bool TryParse(string s, out RowId value) {
            value = Null;

            if (String.IsNullOrEmpty(s))
                return false;

            var index = s.IndexOf("-", StringComparison.Ordinal);
            if (index == -1)
                return false;

            var s1 = s.Substring(0, index);
            var s2 = s.Substring(index + 1);

            int v1;
            int v2;
            if (!Int32.TryParse(s1, out v1))
                return false;
            if (!Int32.TryParse(s2, out v2))
                return false;

            value = new RowId(v1, v2);
            return true;
        }

        public static RowId Parse(string s) {
            RowId rowId;
            if (!TryParse(s, out rowId))
                throw new FormatException("Unable to parse the given string into a valid ROWID.");

            return rowId;
        }
    }
}