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using System;
using System.Collections;
namespace System.Data.Common
{
/// <summary>
/// Summary description for ComparerFactory.
/// </summary>
public class DBComparerFactory
{
private static IComparer comparableComparer = new ComparebleComparer();
private static IComparer ignoreCaseComparer = new IgnoreCaseComparer();
private static IComparer caseComparer = new CaseComparer();
private static IComparer byteArrayComparer = new ByteArrayComparer();
private static Type icomparerType = typeof (IComparable);
public static IComparer GetComparer (Type type, bool ignoreCase)
{
if (type == typeof (string)) {
if (ignoreCase)
return ignoreCaseComparer;
return caseComparer;
}
if (icomparerType.IsAssignableFrom(type))
return comparableComparer;
if (type == typeof (byte[]))
return byteArrayComparer;
return null;
}
class ComparebleComparer :IComparer
{
#region IComparer Members
public int Compare(object x, object y)
{
if (x == DBNull.Value) {
if (y == DBNull.Value)
return 0;
return -1;
}
if (y == DBNull.Value)
return 1;
return ((IComparable)x).CompareTo (y);
}
#endregion
}
class CaseComparer : IComparer
{
#region IComparer Members
public int Compare(object x, object y)
{
if (x == DBNull.Value) {
if (y == DBNull.Value)
return 0;
return -1;
}
if (y == DBNull.Value)
return 1;
return String.Compare ((string)x, (string)y, false);
}
#endregion
}
class IgnoreCaseComparer : IComparer
{
#region IComparer Members
public int Compare(object x, object y)
{
if (x == DBNull.Value) {
if (y == DBNull.Value)
return 0;
return -1;
}
if (y == DBNull.Value)
return 1;
return String.Compare ((string)x, (string)y, true);
}
#endregion
}
class ByteArrayComparer : IComparer
{
#region IComparer Members
public int Compare(object x, object y)
{
if (x == DBNull.Value) {
if (y == DBNull.Value)
return 0;
return -1;
}
if (y == DBNull.Value)
return 1;
byte[] o1 = (byte[])x;
byte[] o2 = (byte[])y;
int len = o1.Length;
int lenb = o2.Length;
for (int i = 0; ; i++) {
int a = 0;
int b = 0;
if (i < len) {
a = o1[i];
}
else if (i >= lenb) {
return 0;
}
if (i < lenb) {
b = o2[i];
}
if (a > b) {
return 1;
}
if (b > a) {
return -1;
}
}
}
#endregion
}
}
}
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