Fishery

2022-10-24 18:56:18 +02:00
parent 01ef055ff2
commit 9cdc8ccb4f
70 changed files with 19754 additions and 4 deletions
@@ -0,0 +1,106 @@
+// Copyright (c) 2022 bradson
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+using System.Linq;
+using System.Runtime.CompilerServices;
+
+namespace FisheryLib.FunctionPointers;
+public static class GetHashCode<T>
+{
+	public static readonly unsafe delegate*<T, int> Default = (delegate*<T, int>)FunctionPointers.GetHashCode.MakeDelegate(typeof(T));
+}
+
+public static class GetHashCode
+{
+	public static class Methods
+	{
+		public static int Byte(byte obj)
+			=> obj;
+
+		public static int Int(int obj)
+			=> obj;
+
+		public static int Uint(uint obj)
+			=> (int)obj;
+
+		public static int Ushort(ushort obj)
+			=> obj;
+
+		public static unsafe int VoidPtr(void* obj)
+			=> (int)obj;
+
+		public static int Enum<T>(T obj) where T : struct
+			=> JitHelpers.UnsafeEnumCast(obj).GetHashCode();
+
+		public static int SbyteEnum<T>(T obj) where T : struct
+			=> ((sbyte)JitHelpers.UnsafeEnumCast(obj)).GetHashCode();
+
+		public static int ShortEnum<T>(T obj) where T : struct
+			=> ((short)JitHelpers.UnsafeEnumCast(obj)).GetHashCode();
+
+		public static int LongEnum<T>(T obj) where T : struct
+			=> JitHelpers.UnsafeEnumCastLong(obj).GetHashCode();
+
+		public static int ValueType<T>(T obj) where T : struct
+			=> obj.GetHashCode();
+
+		public static int Nullable<T>(T? obj) where T : struct
+			=> obj.GetHashCode();
+
+		public static int Reference<T>(T obj) where T : class
+			=> RuntimeHelpers.GetHashCode(obj);
+
+		public static int Object<T>(T obj)
+			=> obj?.GetHashCode() ?? 0;
+	}
+
+	internal static unsafe IntPtr MakeDelegate(Type type)
+		=> _getHashCodeMethods.Where(m => !m.IsGenericMethod)
+			.FirstOrDefault(m
+				=> m.GetParameters().First().ParameterType == type)
+			is { } specializedMethod
+		? specializedMethod.GetFunctionPointer()
+		: type.IsNullable(out var genericArgument)
+			&& genericArgument.IsAssignableTo(typeof(IEquatable<>), genericArgument)
+		? GetMethod(nameof(Methods.Nullable)).MakeGenericMethod(genericArgument).GetFunctionPointer()
+		: GetMethod(
+			type.IsEnum
+			? Type.GetTypeCode(Enum.GetUnderlyingType(type))
+				switch
+				{
+					TypeCode.Int16 => nameof(Methods.ShortEnum),
+					TypeCode.SByte => nameof(Methods.SbyteEnum),
+					TypeCode.Byte
+					or TypeCode.UInt16
+					or TypeCode.Int32
+					or TypeCode.UInt32 => nameof(Methods.Enum),
+					TypeCode.Int64
+					or TypeCode.UInt64 => nameof(Methods.LongEnum),
+					_ => ThrowHelper.ThrowNotSupportedException<string>()
+				}
+			: type.IsValueType
+			? nameof(Methods.ValueType)
+			: nameof(Methods.Object)
+		).MakeGenericMethod(type).GetFunctionPointer();
+
+	private static MethodInfo GetMethod(string name)
+		=> Array.Find(_getHashCodeMethods, m => m.Name == name);
+
+	private static MethodInfo[] _getHashCodeMethods
+		= typeof(Methods)
+		.GetMethods(BindingFlags.Static | BindingFlags.Public | BindingFlags.DeclaredOnly)
+		.Where(m
+			=> m.ReturnType == typeof(int)
+			&& m.GetParameters().Length == 1)
+		.ToArray();
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	private static unsafe delegate*<V, int> Cast<T,V>(delegate*<T, int> @delegate)
+		=> (delegate*<V, int>)@delegate;
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	private static unsafe delegate*<T, int> CastVoid<T>(delegate*<void*, int> @delegate)
+		=> (delegate*<T, int>)@delegate;
+}