Calculates the intersection set of two IEnumerable - CSharp System.Collections.Generic

CSharp examples for System.Collections.Generic:IEnumerable

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Description

Calculates the intersection set of two IEnumerable

Demo Code

/*// w  ww  . j  ava  2 s.co m
    Copyright (C) 2007-2017 Team MediaPortal
    http://www.team-mediaportal.com

    This file is part of MediaPortal 2

    MediaPortal 2 is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    MediaPortal 2 is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with MediaPortal 2. If not, see <http://www.gnu.org/licenses/>.
*/
using System.Linq;
using System.Collections.Generic;
using System.Collections;
using System;

public class Main{
        /// <summary>
    /// Calculates the intersection set of <paramref name="c1"/> and <paramref name="c2"/> and returns it.
    /// If the type parameters of the collections differ, the collection with the more general element type
    /// must be used at the second position.
    /// </summary>
    /// <typeparam name="S">Element type of the first source collection. May be more specific than
    /// the type parameter of the second collection.</typeparam>
    /// <typeparam name="T">Element type of the second source collection and the result collection.
    /// May be more general than the type parameter of the first collection <see cref="S"/>.</typeparam>
    /// <param name="c1">First source collection.</param>
    /// <param name="c2">Second source collection</param>
    /// <returns>Intersection of <paramref name="c1"/> and <paramref name="c2"/>.</returns>
    public static ICollection<T> Intersection<S, T>(IEnumerable<S> c1, IEnumerable<T> c2) where S: T
    {
      ICollection<T> result = new List<T>();
      ICollection<S> x1 = c1 as ICollection<S>;
      if (x1 != null)
      { // First argument implements ICollection<S>
        foreach (S s in c2)
          if (x1.Contains(s))
            result.Add(s);
      }
      else
      {
        ICollection<T> x2 = c2 as ICollection<T> ?? new List<T>(c2); // If second argument also doesn't implement ICollection<T>, create a new list
        foreach (S s in c1)
          if (x2.Contains(s))
            result.Add(s);
      }
      return result;
    }
}

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