C#/EnumerableCompare.cs

   1 using System;
   2 using System.Collections.Generic;
   3
   4 namespace IEnumerableExtras
   5 {
   6     /// <summary>
   7     /// Compare <see cref="IEnumerable{T}"/> extension.
   8     /// </summary>
   9     public static class EnumerableCompare
  10     {
  11         /// <summary>
  12         /// Compare this instance of <see cref="IEnumerable{TValue}"/> with another instance
  13         /// if same type using equivalence function and produce a list of items present
  14         /// in both collections and a list of items missing from second collection.
  15         /// </summary>
  16         /// <typeparam name="TValue"></typeparam>
  17         /// <param name="a"></param>
  18         /// <param name="b"></param>
  19         /// <param name="missingFromOther"></param>
  20         /// <param name="equivFunc"></param>
  21         /// <returns></returns>
  22         public static IEnumerable<Pair<TValue>> Compare< TValue >( this IEnumerable<TValue> a,
  23                                                                    IEnumerable<TValue> b,
  24                                                                    out IEnumerable<TValue> missingFromOther,
  25                                                                    Func<TValue, TValue, bool> equivFunc )
  26         {
  27             List<Pair<TValue>> common = new List<Pair<TValue>>();
  28             List<TValue> missing = new List<TValue>();
  29
  30             foreach ( TValue fromA in a )
  31             {
  32                 bool found = false;
  33
  34                 foreach ( TValue fromB in b )
  35                 {
  36                     if ( equivFunc( fromA, fromB ) )
  37                     {
  38                         common.Add( new Pair<TValue>( fromA, fromB ) );
  39                         found = true;
  40                         break;
  41                     }
  42                 }
  43
  44                 if ( !found )
  45                 {
  46                     missing.Add( fromA );
  47                 }
  48             }
  49
  50             missingFromOther = missing;
  51             return common;
  52         }
  53     }
  54 }