BizHawk/BizHawk.Emulation.Common/Base Implementations/BasicServiceProvider.cs

90 lines
2.7 KiB
C#

using System;
using System.Collections.Generic;
using System.Linq;
namespace BizHawk.Emulation.Common
{
/// <summary>
/// A generic implementation of IEmulatorService provider that provides
/// this functionality to any core.
/// The provider will scan an IEmulator and register all IEmulatorServices
/// that the core object itself implements. In addition it provides
/// a Register() method to allow the core to pass in any additional services
/// </summary>
/// <seealso cref="IEmulatorServiceProvider"/>
public class BasicServiceProvider : IEmulatorServiceProvider
{
private readonly Dictionary<Type, object> _services = new Dictionary<Type, object>();
public BasicServiceProvider(IEmulator core)
{
// simplified logic here doesn't scan for possible services; just adds what it knows is implemented by the core
// this removes the possibility of automagically picking up a service in a nested class, (find the type, then
// find the field), but we're going to keep such logic out of the basic provider. anything the passed
// core doesn't implement directly needs to be added with Register()
// this also fully allows services that are not IEmulatorService
Type coreType = core.GetType();
var services = coreType.GetInterfaces()
.Where(t => typeof(IEmulatorService).IsAssignableFrom(t))
.Where(t => t != typeof(IEmulatorService));
foreach (Type service in services)
{
_services.Add(service, core);
}
// add the actual instantiated type and any types in the hierarchy
// except for object because that would be dumb (or would it?)
while (coreType != typeof(object))
{
_services.Add(coreType, core);
coreType = coreType.BaseType;
}
}
/// <summary>the core can call this to register an additional service</summary>
/// <typeparam name="T">The <see cref="IEmulatorService"/> to register</typeparam>
/// <exception cref="ArgumentNullException"><paramref name="provider"/> is null</exception>
public void Register<T>(T provider)
where T : IEmulatorService
{
if (provider == null)
{
throw new ArgumentNullException(nameof(provider));
}
_services[typeof(T)] = provider;
}
public T GetService<T>()
where T : IEmulatorService
{
return (T)GetService(typeof(T));
}
public object GetService(Type t)
{
if (_services.TryGetValue(t, out var service))
{
return service;
}
return null;
}
public bool HasService<T>()
where T : IEmulatorService
{
return HasService(typeof(T));
}
public bool HasService(Type t)
{
return _services.ContainsKey(t);
}
public IEnumerable<Type> AvailableServices =>_services.Select(d => d.Key);
}
}