/// <summary>
/// Compares two sequences and returns the added or removed items.
/// </summary>
/// <typeparam name="T">Implements IEquatable</typeparam>
/// <param name="fresh">Recent sequence</param>
/// <param name="old">Older sequence used as base of comparison</param>
/// <returns></returns>
public static IModifiedSet <T> Diff <T>(this IEnumerable <T> fresh, IEnumerable <T> old) where T : IEquatable <T>
{
if (fresh == null)
{
throw new ArgumentNullException("fresh");
}
if (old == null)
{
throw new ArgumentNullException("old");
}
var mods = new ModifiedSet <T>();
foreach (var item in old)
{
if (!fresh.Contains(item))
{
mods.RemovedItem(item);
}
}
foreach (var item in fresh)
{
if (!old.Contains(item))
{
mods.AddedItem(item);
}
}
return(mods);
}
/// <summary>
/// Compares two sequences and returns the added or removed items.
/// Use this when T doesn't implement IEquatable
/// </summary>
/// <typeparam name="T">Type</typeparam>
/// <param name="fresh">Recent sequence</param>
/// <param name="old">Older sequence used as base of comparison</param>
/// <param name="match">function to check equality</param>
/// <returns></returns>
public static IModifiedSet <T> Compare <T>(this IEnumerable <T> fresh, IEnumerable <T> old, Func <T, T, bool> match)
{
if (fresh == null)
{
throw new ArgumentNullException("fresh");
}
if (old == null)
{
throw new ArgumentNullException("old");
}
if (match == null)
{
throw new ArgumentNullException("match");
}
var mods = new ModifiedSet <T>();
foreach (var item in old)
{
if (!fresh.Any(d => match(d, item)))
{
mods.RemovedItem(item);
}
}
foreach (var item in fresh)
{
if (!old.Any(d => match(d, item)))
{
mods.AddedItem(item);
}
}
return(mods);
}
/// <summary>
/// Compares two sequences and returns the result.
/// This special case method is best used when you have identifiable objects that can change their content/value but not their id.
/// </summary>
/// <typeparam name="T">Implements IEquatable</typeparam>
/// <param name="fresh">Recent sequence</param>
/// <param name="old">Older sequence used as base of comparison</param>
/// <param name="detectChange">Delegate to determine if the items are identical.
/// First parameter is new item, second is the item used as base for comparison</param>
/// <returns></returns>
public static IModifiedSet <T> WhatChanged <T>(this IEnumerable <T> fresh, IEnumerable <T> old,
Func <T, T, bool> detectChange) where T : IEquatable <T>
{
if (fresh == null)
{
throw new ArgumentNullException("fresh");
}
if (old == null)
{
throw new ArgumentNullException("old");
}
if (detectChange == null)
{
throw new ArgumentNullException("detectChange");
}
var mods = new ModifiedSet <T>();
foreach (var item in old)
{
if (!fresh.Any(d => d.Equals(item)))
{
mods.RemovedItem(item);
}
}
foreach (var item in fresh)
{
if (!old.Any(d => d.Equals(item)))
{
mods.AddedItem(item);
}
else
{
var oldItem = old.First(d => d.Equals(item));
if (detectChange(item, oldItem))
{
mods.ModifiedItem(oldItem, item);
}
}
}
return(mods);
}