Returns the first element contained in both, source and candidates. : IEnumerable « Collections Data Structure « C# / C Sharp

1. C# / C Sharp
2. Collections Data Structure
3. IEnumerable

Returns the first element contained in both, source and candidates.

    

#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"/> &lt;&lt;&lt; <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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