Linq Extension Each

gistfile1.cs

using System;

// Stable
namespace System.Linq
{
	using System.Linq;
	using System.Collections;
	using System.Collections.Generic;

	public static class LinqExtensions
	{
		#region Each, LazyEach

		/// <summary>
		/// Lazy, chainable ForEach loop
		/// </summary>
		/// <returns>The each.</returns>
		/// <param name="source">Source.</param>
		/// <param name="action">Action.</param>
		/// <typeparam name="TResult">The 1st type parameter.</typeparam>
		public static IEnumerable<TResult> LazyEach<TResult> (this IEnumerable<TResult> source, Action<TResult> action)
		{
			foreach (var elem in source) {
				action (elem);
				yield return elem;
			}
		}

		/// <summary>
		/// Lazy, chainable ForEach loop with return value
		/// </summary>
		/// <returns>The each.</returns>
		/// <param name="source">Source.</param>
		/// <param name="action">Action.</param>
		/// <typeparam name="TResult">The 1st type parameter.</typeparam>
		public static IEnumerable<TResult> LazyEach<TResult> (this IEnumerable<TResult> source, Func<TResult, TResult> action)
		{
			foreach (var elem in source) {
				yield return action (elem);
			}
		}

		/// <summary>
		/// Unchainable ForEach loop
		/// </summary>
		/// <param name="source">Source.</param>
		/// <param name="action">Action.</param>
		/// <typeparam name="TResult">The 1st type parameter.</typeparam>
		public static IEnumerable<TResult> Each<TResult> (this IEnumerable<TResult> source, Action<TResult> action)
		{
			var actual = LazyEach (source, action);
			return actual.Done ();
		}

		/// <summary>
		/// Unchainable ForEach loop with return value
		/// </summary>
		/// <param name="source">Source.</param>
		/// <param name="action">Action.</param>
		/// <typeparam name="TResult">The 1st type parameter.</typeparam>
		public static IEnumerable<TResult> Each<TResult> (this IEnumerable<TResult> source, Func<TResult, TResult> action)
		{
			var actual = LazyEach (source, action);
			return actual.Done ();
		}


		#endregion

		#region Done

		/// <summary>
		/// Evaluates a lazy chained operation.
		/// Should be used at the very end of a Linq chain,
		/// and only if the last extension in the chain is lazy
		/// </summary>
		/// <param name="source">Source.</param>
		/// <typeparam name="TResult">The 1st type parameter.</typeparam>
		public static IEnumerable<TResult> Done<TResult> (this IEnumerable<TResult> source)
		{
			foreach (var elem in source)
				;

			return source;
		}

		#endregion
	}
}