我写了一些扩展方法来帮助我。
namespace System.Linq
{
/// <summary>
/// Class to hold extension methods to Linq.
/// </summary>
public static class LinqExtensions
{
/// <summary>
/// Changes all elements of IEnumerable by the change function
/// </summary>
/// <param name="enumerable">The enumerable where you want to change stuff</param>
/// <param name="change">The way you want to change the stuff</param>
/// <returns>An IEnumerable with all changes applied</returns>
public static IEnumerable<T> Change<T>(this IEnumerable<T> enumerable, Func<T, T> change )
{
ArgumentCheck.IsNullorWhiteSpace(enumerable, "enumerable");
ArgumentCheck.IsNullorWhiteSpace(change, "change");
foreach (var item in enumerable)
{
yield return change(item);
}
}
/// <summary>
/// Changes all elements of IEnumerable by the change function, that fullfill the where function
/// </summary>
/// <param name="enumerable">The enumerable where you want to change stuff</param>
/// <param name="change">The way you want to change the stuff</param>
/// <param name="where">The function to check where changes should be made</param>
/// <returns>
/// An IEnumerable with all changes applied
/// </returns>
public static IEnumerable<T> ChangeWhere<T>(this IEnumerable<T> enumerable,
Func<T, T> change,
Func<T, bool> @where)
{
ArgumentCheck.IsNullorWhiteSpace(enumerable, "enumerable");
ArgumentCheck.IsNullorWhiteSpace(change, "change");
ArgumentCheck.IsNullorWhiteSpace(@where, "where");
foreach (var item in enumerable)
{
if (@where(item))
{
yield return change(item);
}
else
{
yield return item;
}
}
}
/// <summary>
/// Changes all elements of IEnumerable by the change function that do not fullfill the except function
/// </summary>
/// <param name="enumerable">The enumerable where you want to change stuff</param>
/// <param name="change">The way you want to change the stuff</param>
/// <param name="where">The function to check where changes should not be made</param>
/// <returns>
/// An IEnumerable with all changes applied
/// </returns>
public static IEnumerable<T> ChangeExcept<T>(this IEnumerable<T> enumerable,
Func<T, T> change,
Func<T, bool> @where)
{
ArgumentCheck.IsNullorWhiteSpace(enumerable, "enumerable");
ArgumentCheck.IsNullorWhiteSpace(change, "change");
ArgumentCheck.IsNullorWhiteSpace(@where, "where");
foreach (var item in enumerable)
{
if (!@where(item))
{
yield return change(item);
}
else
{
yield return item;
}
}
}
/// <summary>
/// Update all elements of IEnumerable by the update function (only works with reference types)
/// </summary>
/// <param name="enumerable">The enumerable where you want to change stuff</param>
/// <param name="update">The way you want to change the stuff</param>
/// <returns>
/// The same enumerable you passed in
/// </returns>
public static IEnumerable<T> Update<T>(this IEnumerable<T> enumerable,
Action<T> update) where T : class
{
ArgumentCheck.IsNullorWhiteSpace(enumerable, "enumerable");
ArgumentCheck.IsNullorWhiteSpace(update, "update");
foreach (var item in enumerable)
{
update(item);
}
return enumerable;
}
/// <summary>
/// Update all elements of IEnumerable by the update function (only works with reference types)
/// where the where function returns true
/// </summary>
/// <param name="enumerable">The enumerable where you want to change stuff</param>
/// <param name="update">The way you want to change the stuff</param>
/// <param name="where">The function to check where updates should be made</param>
/// <returns>
/// The same enumerable you passed in
/// </returns>
public static IEnumerable<T> UpdateWhere<T>(this IEnumerable<T> enumerable,
Action<T> update, Func<T, bool> where) where T : class
{
ArgumentCheck.IsNullorWhiteSpace(enumerable, "enumerable");
ArgumentCheck.IsNullorWhiteSpace(update, "update");
foreach (var item in enumerable)
{
if (where(item))
{
update(item);
}
}
return enumerable;
}
/// <summary>
/// Update all elements of IEnumerable by the update function (only works with reference types)
/// Except the elements from the where function
/// </summary>
/// <param name="enumerable">The enumerable where you want to change stuff</param>
/// <param name="update">The way you want to change the stuff</param>
/// <param name="where">The function to check where changes should not be made</param>
/// <returns>
/// The same enumerable you passed in
/// </returns>
public static IEnumerable<T> UpdateExcept<T>(this IEnumerable<T> enumerable,
Action<T> update, Func<T, bool> where) where T : class
{
ArgumentCheck.IsNullorWhiteSpace(enumerable, "enumerable");
ArgumentCheck.IsNullorWhiteSpace(update, "update");
foreach (var item in enumerable)
{
if (!where(item))
{
update(item);
}
}
return enumerable;
}
}
}
我正在这样使用它：
List<int> exampleList = new List<int>()
{
1, 2 , 3
};
//2 , 3 , 4
var updated1 = exampleList.Change(x => x + 1);
//10, 2, 3
var updated2 = exampleList
.ChangeWhere( changeItem => changeItem * 10, // change you want to make
conditionItem => conditionItem < 2); // where you want to make the change
//1, 0, 0
var updated3 = exampleList
.ChangeExcept(changeItem => 0, //Change elements to 0
conditionItem => conditionItem == 1); //everywhere but where element is 1
供参考的参数检查：
/// <summary>
/// Class for doing argument checks
/// </summary>
public static class ArgumentCheck
{
/// <summary>
/// Checks if a value is string or any other object if it is string
/// it checks for nullorwhitespace otherwhise it checks for null only
/// </summary>
/// <typeparam name="T">Type of the item you want to check</typeparam>
/// <param name="item">The item you want to check</param>
/// <param name="nameOfTheArgument">Name of the argument</param>
public static void IsNullorWhiteSpace<T>(T item, string nameOfTheArgument = "")
{
Type type = typeof(T);
if (type == typeof(string) ||
type == typeof(String))
{
if (string.IsNullOrWhiteSpace(item as string))
{
throw new ArgumentException(nameOfTheArgument + " is null or Whitespace");
}
}
else
{
if (item == null)
{
throw new ArgumentException(nameOfTheArgument + " is null");
}
}
}
}