C#/EnumerableMap.cs

   1 using System;
   2 using System.Collections;
   3 using System.Collections.Generic;
   4
   5 namespace IEnumerableExtras
   6 {
   7     /// <summary>
   8     /// <see cref="IEnumerable{T}"/> map extension.
   9     /// </summary>
  10     public static class EnumerableMap
  11     {
  12         /// <summary>
  13         /// Produce new instance of <see cref="IEnumerable{TResult}"/> by applying
  14         /// predicate to each element in this instance of <see cref="IEnumerable"/>.
  15         /// </summary>
  16         /// <typeparam name="TResult">Resulting collection item type.</typeparam>
  17         /// <param name="collection">This instance of <see cref="IEnumerable{T}"/>.</param>
  18         /// <param name="predicate">Function returnting objects of type <typeparamref name="TResult"/> based on objects of type <typeparamref name="T"/>.</param>
  19         /// <returns></returns>
  20         public static IEnumerable<TResult> Map< TResult >( this IEnumerable collection, Func<object, TResult> predicate )
  21         {
  22             foreach ( var item in collection )
  23             {
  24                 yield return predicate( item );
  25             }
  26         }
  27
  28         /// <summary>
  29         /// Produce new instance of <see cref="IEnumerable{TResult}"/> by applying
  30         /// predicate to each element in this instance of <see cref="IEnumerable{T}"/>.
  31         /// </summary>
  32         /// <typeparam name="T">This collection's item type.</typeparam>
  33         /// <typeparam name="TResult">Resulting collection item type.</typeparam>
  34         /// <param name="collection">This instance of <see cref="IEnumerable{T}"/>.</param>
  35         /// <param name="predicate">Function returnting objects of type <typeparamref name="TResult"/> based on objects of type <typeparamref name="T"/>.</param>
  36         /// <returns></returns>
  37         public static IEnumerable<TResult> Map< T, TResult >( this IEnumerable<T> collection, Func<T, TResult> predicate )
  38         {
  39             foreach ( var item in collection )
  40             {
  41                 yield return predicate( item );
  42             }
  43         }
  44
  45         public static IEnumerable<TResult> Map< T, TResult >( this IEnumerable<T> collection, Func<T, int, TResult> predicate )
  46         {
  47             int i = 0;
  48             foreach ( var item in collection )
  49             {
  50                 yield return predicate( item, i++ );
  51             }
  52         }
  53     }
  54 }