bbradson
56 lines
1.8 KiB
C#
56 lines
1.8 KiB
C#
// Copyright (c) 2022 bradson
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this
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// file, You can obtain one at https://mozilla.org/MPL/2.0/.
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using System.Collections.Concurrent;
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using JetBrains.Annotations;
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namespace FisheryLib;
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[PublicAPI]
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public abstract class SingletonFactory<T_base> where T_base : notnull
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{
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/// <summary>
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/// Get a Singleton instance of a type derived from T_base
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/// </summary>
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/// <typeparam name="T">The type of the instance</typeparam>
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/// <returns>The Singleton instance</returns>
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public static T Get<T>() where T : T_base => (T)GetInternal(typeof(T));
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/// <summary>
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/// Get a Singleton instance of a type derived from T_base
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/// </summary>
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/// <param name="type">The type of the instance</param>
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/// <returns>The Singleton instance</returns>
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public static T_base Get(Type type)
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{
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if (!typeof(T_base).IsAssignableFrom(type))
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{
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ThrowHelper.ThrowArgumentException(
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$"Parameters for {typeof(T_base).Name}.Get must be assignable from Type {
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typeof(T_base).Name}. Got {type.FullDescription()} instead.");
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}
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return GetInternal(type);
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}
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/// <summary>
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/// protected to allow declaring of default values on derived types. Do not directly invoke this constructor or
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/// expose it as public.
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/// </summary>
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protected SingletonFactory()
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{
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if (_instances.ContainsKey(GetType()))
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{
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ThrowHelper.ThrowInvalidOperationException(
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$"Tried creating a second instance of {GetType().Name}. Only the {
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typeof(T_base).Name}.Get method should be used for instantiation.");
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}
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}
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private static T_base GetInternal(Type type)
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=> _instances.GetOrAdd(type, static type => (T_base)Activator.CreateInstance(type, true));
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private static readonly ConcurrentDictionary<Type, T_base> _instances = new();
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} |