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//
// DataRowComparer_1.cs
//
// Author:
// Atsushi Enomoto <atsushi@ximian.com>
//
// Copyright (C) 2008 Novell, Inc. http://www.novell.com
//
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Collections.Generic;
namespace System.Data
{
public sealed class DataRowComparer<TRow> : IEqualityComparer<TRow> where TRow : DataRow
{
static readonly DataRowComparer<TRow> default_instance = new DataRowComparer<TRow> ();
public static DataRowComparer<TRow> Default {
get { return default_instance; }
}
private DataRowComparer ()
{
}
// LAMESPEC: neither of the parameters throws ArgumentNullException if it's null
public bool Equals (TRow leftRow, TRow rightRow)
{
if (object.ReferenceEquals (leftRow, rightRow))
return true;
if (leftRow == null || rightRow == null)
return false;
int columnCount = leftRow.Table.Columns.Count;
if (columnCount != rightRow.Table.Columns.Count)
return false;
for (int i = 0; i < columnCount; i++)
if (!ColumnsEqual (leftRow [i], rightRow [i]))
return false;
return true;
}
bool ColumnsEqual (object leftCol, object rightCol)
{
if (object.ReferenceEquals (leftCol, rightCol))
return true;
if (leftCol == null || rightCol == null)
return false;
ValueType vt = leftCol as ValueType;
if (vt != null && vt.Equals (rightCol))
return true;
return leftCol.Equals (rightCol);
}
public int GetHashCode (TRow row)
{
if (row == null)
throw new ArgumentNullException ("row");
DataTable table = row.Table;
if (table == null)
throw new ArgumentException ("The source DataRow objects does not belong to a DataTable.");
DataColumnCollection columns = table.Columns;
int columnCount = columns.Count;
if (columnCount == 0)
return 0;
int ret = 0;
object o;
for (int i = 0; i < columnCount; i++) {
o = row [i];
if (o == null)
continue;
ret ^= o.GetHashCode ();
}
return ret;
}
}
}
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