#region License
/*
* Copyright 2002-2005 the original author or authors.
*
* 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.
*/
#endregion
#region Imports
using System;
using System.Collections;
#endregion
namespace Spring.Core{
/// <summary>
/// Comparator implementation for <see cref="Spring.Core.IOrdered"/> objects, sorting by
/// order value ascending (resp. by priority descending).
/// </summary>
/// <remarks>
/// <p>
/// Non-<see cref="Spring.Core.IOrdered"/> objects are treated as greatest order values,
/// thus ending up at the end of a list, in arbitrary order (just like same order values of
/// <see cref="Spring.Core.IOrdered"/> objects).
/// </p>
/// </remarks>
/// <author>Juergen Hoeller</author>
/// <author>Aleksandar Seovic (.Net)</author>
[Serializable]
public class OrderComparator : IComparer
{
/// <summary>
/// Compares two objects and returns a value indicating whether one is less than,
/// equal to or greater than the other.
/// </summary>
/// <remarks>
/// <p>
/// Uses direct evaluation instead of <see cref="System.Int32.CompareTo(object)"/>
/// to avoid unnecessary boxing.
/// </p>
/// </remarks>
/// <param name="o1">The first object to compare.</param>
/// <param name="o2">The second object to compare.</param>
/// <returns>
/// -1 if first object is less then second, 1 if it is greater, or 0 if they are equal.
/// </returns>
public virtual int Compare(object o1, object o2)
{
IOrdered o1lhs = o1 as IOrdered;
IOrdered o2rhs = o2 as IOrdered;
int lhs = o1lhs != null ? o1lhs.Order : Int32.MaxValue;
int rhs = o2rhs != null ? o2rhs.Order : Int32.MaxValue;
if (lhs < rhs)
{
return - 1;
}
else if (lhs > rhs)
{
return 1;
}
else
{
return CompareEqualOrder(o1, o2);
}
}
/// <summary>
/// Handle the case when both objects have equal sort order priority. By default returns 0,
/// but may be overriden for handling special cases.
/// </summary>
/// <param name="o1">The first object to compare.</param>
/// <param name="o2">The second object to compare.</param>
/// <returns>
/// -1 if first object is less then second, 1 if it is greater, or 0 if they are equal.
/// </returns>
protected virtual int CompareEqualOrder(object o1, object o2)
{
return 0;
}
}
}
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