Mega Code Archive
Returns the first element contained in both, source and candidates
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#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;
using System.Reflection;
#endregion
namespace Spring.Util
{
/// <summary>
/// Miscellaneous collection utility methods.
/// </summary>
/// <remarks>
/// Mainly for internal use within the framework.
/// </remarks>
/// <author>Mark Pollack (.NET)</author>
public sealed class CollectionUtils
{
/// <summary>
/// Returns the first element contained in both, <paramref name="source"/> and <paramref name="candidates"/>.
/// </summary>
/// <remarks>The implementation assumes that <paramref name="candidates"/> <<< <paramref name="source"/></remarks>
/// <param name="source">the source enumerable. may be <c>null</c></param>
/// <param name="candidates">the list of candidates to match against <paramref name="source"/> elements. may be <c>null</c></param>
/// <returns>the first element found in both enumerables or <c>null</c></returns>
public static object FindFirstMatch(IEnumerable source, IEnumerable candidates)
{
if (IsEmpty(source) || IsEmpty(candidates))
{
return null;
}
IList candidateList = candidates as IList;
if (candidateList == null)
{
if (candidates is ICollection)
{
candidateList = new ArrayList((ICollection)candidates);
}
else
{
candidateList = new ArrayList();
foreach (object el in candidates)
{
candidateList.Add(el);
}
}
}
foreach (object sourceElement in source)
{
if (candidateList.Contains(sourceElement))
{
return sourceElement;
}
}
return null;
}
/// <summary>
/// Determines whether the specified collection is null or empty.
/// </summary>
/// <param name="enumerable">The collection to check.</param>
/// <returns>
/// <c>true</c> if the specified collection is empty or null; otherwise, <c>false</c>.
/// </returns>
public static bool IsEmpty(IEnumerable enumerable)
{
if (enumerable == null)
return true;
if (enumerable is ICollection)
{
return (0 == ((ICollection)enumerable).Count);
}
IEnumerator it = enumerable.GetEnumerator();
if (!it.MoveNext())
{
return true;
}
return false;
}
/// <summary>
/// Determines whether the specified collection is null or empty.
/// </summary>
/// <param name="collection">The collection to check.</param>
/// <returns>
/// <c>true</c> if the specified collection is empty or null; otherwise, <c>false</c>.
/// </returns>
public static bool IsEmpty(ICollection collection)
{
return (collection == null || collection.Count == 0);
}
/// <summary>
/// Determines whether the specified dictionary is null empty.
/// </summary>
/// <param name="dictionary">The dictionary to check.</param>
/// <returns>
/// <c>true</c> if the specified dictionary is empty or null; otherwise, <c>false</c>.
/// </returns>
public static bool IsEmpty(IDictionary dictionary)
{
return (dictionary == null || dictionary.Count == 0);
}
}
}
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