baseline: OpenMU upstream b5a0961 (fresh source)

src/GameLogic/EnumerableExtensions.cs

@@ -0,0 +1,134 @@
+// <copyright file="EnumerableExtensions.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameLogic;
+
+/// <summary>
+/// Extensions for <see cref="IEnumerable{T}"/>.
+/// </summary>
+public static class EnumerableExtensions
+{
+    /// <summary>
+    /// Executes the <paramref name="action"/> for each element of <paramref name="enumerable"/>.
+    /// </summary>
+    /// <typeparam name="T">The generic type of the enumerable.</typeparam>
+    /// <param name="enumerable">The enumerable.</param>
+    /// <param name="action">The action which should be executed for each element.</param>
+    /// <exception cref="System.ArgumentNullException">action.</exception>
+    public static void ForEach<T>(this IEnumerable<T> enumerable, Action<T> action)
+    {
+        if (action is null)
+        {
+            throw new ArgumentNullException(nameof(action));
+        }
+
+        foreach (var item in enumerable)
+        {
+            action(item);
+        }
+    }
+
+    /// <summary>
+    /// Executes the <paramref name="action"/> for each element of <paramref name="enumerable"/>.
+    /// </summary>
+    /// <typeparam name="T">The generic type of the enumerable.</typeparam>
+    /// <param name="enumerable">The enumerable.</param>
+    /// <param name="action">The action which should be executed for each element.</param>
+    /// <exception cref="System.ArgumentNullException">action.</exception>
+    public static async ValueTask ForEachAsync<T>(this IEnumerable<T> enumerable, Func<T, ValueTask> action)
+    {
+        if (action is null)
+        {
+            throw new ArgumentNullException(nameof(action));
+        }
+
+        foreach (var item in enumerable)
+        {
+            await action(item).ConfigureAwait(false);
+        }
+    }
+
+    /// <summary>
+    /// Returns the enumerable as list, by either casting it or creating it.
+    /// </summary>
+    /// <typeparam name="T">The type of the list elements.</typeparam>
+    /// <param name="enumerable">The enumerable.</param>
+    /// <returns>The list.</returns>
+    public static IList<T> AsList<T>(this IEnumerable<T> enumerable)
+    {
+        if (enumerable is IList<T> list)
+        {
+            return list;
+        }
+
+        return enumerable.ToList();
+    }
+
+    /// <summary>
+    /// Selects a random element of an enumerable.
+    /// </summary>
+    /// <typeparam name="T">The generic type of the enumerable.</typeparam>
+    /// <param name="enumerable">The enumerable.</param>
+    /// <param name="randomizer">The randomizer.</param>
+    /// <returns>The randomly selected element.</returns>
+    public static T? SelectRandom<T>(this IEnumerable<T> enumerable, IRandomizer randomizer)
+    {
+        var list = enumerable as IList<T> ?? enumerable.ToList();
+        if (list.Count > 0)
+        {
+            var index = randomizer.NextInt(0, list.Count);
+            return list[index];
+        }
+
+        return default;
+    }
+
+    /// <summary>
+    /// Selects a random element of an enumerable.
+    /// </summary>
+    /// <typeparam name="T">The generic type of the enumerable.</typeparam>
+    /// <param name="enumerable">The enumerable.</param>
+    /// <returns>The randomly selected element.</returns>
+    public static T? SelectRandom<T>(this IEnumerable<T> enumerable) => SelectRandom(enumerable, Rand.GetRandomizer());
+
+    /// <summary>
+    /// Selects a random weighted element of an enumerable.
+    /// </summary>
+    /// <typeparam name="T">The generic type of the enumerable.</typeparam>
+    /// <param name="enumerable">The enumerable.</param>
+    /// <param name="weights">The weights associated with <paramref name="enumerable" />, respectively.</param>
+    /// <param name="randomizer">The randomizer.</param>
+    /// <returns>The randomly selected weighted element.</returns>
+    public static T? SelectWeightedRandom<T>(this IEnumerable<T> enumerable, IEnumerable<int> weights, IRandomizer randomizer)
+    {
+        var list = enumerable as IList<T> ?? enumerable.ToList();
+        var weightList = weights as IList<int> ?? weights.ToList();
+        if (list.Count > 0 && weightList.Count == list.Count)
+        {
+            var roll = randomizer.NextInt(0, weights.Sum());
+            int inc = 0;
+            for (int i = 0; i < weightList.Count; i++)
+            {
+                inc += weightList[i];
+                if (roll < inc)
+                {
+                    return list[i];
+                }
+            }
+
+            return SelectRandom(enumerable, randomizer);  // Fallback in case there are no weights assigned (>0)
+        }
+
+        return default;
+    }
+
+    /// <summary>
+    /// Selects a random weighted element of an enumerable.
+    /// </summary>
+    /// <typeparam name="T">The generic type of the enumerable.</typeparam>
+    /// <param name="enumerable">The enumerable.</param>
+    /// <param name="weights">The weights associated with <paramref name="enumerable" />, respectively.</param>
+    /// <returns>The randomly selected weighted element.</returns>
+    public static T? SelectWeightedRandom<T>(this IEnumerable<T> enumerable, IEnumerable<int> weights) => SelectWeightedRandom(enumerable, weights, Rand.GetRandomizer());
+}