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//------------------------------------------------------------------------------
// <copyright file="ServiceObjectContainer.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
/*
*/
namespace System.ComponentModel.Design {
using Microsoft.Win32;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Security.Permissions;
/// <devdoc>
/// This is a simple implementation of IServiceContainer.
/// </devdoc>
[HostProtection(SharedState = true)]
public class ServiceContainer : IServiceContainer, IDisposable
{
private ServiceCollection<object> services;
private IServiceProvider parentProvider;
private static Type[] _defaultServices = new Type[] { typeof(IServiceContainer), typeof(ServiceContainer) };
private static TraceSwitch TRACESERVICE = new TraceSwitch("TRACESERVICE", "ServiceProvider: Trace service provider requests.");
/// <devdoc>
/// Creates a new service object container.
/// </devdoc>
public ServiceContainer() {
}
/// <devdoc>
/// Creates a new service object container.
/// </devdoc>
public ServiceContainer(IServiceProvider parentProvider) {
this.parentProvider = parentProvider;
}
/// <devdoc>
/// Retrieves the parent service container, or null
/// if there is no parent container.
/// </devdoc>
private IServiceContainer Container {
get {
IServiceContainer container = null;
if (parentProvider != null) {
container = (IServiceContainer)parentProvider.GetService(typeof(IServiceContainer));
}
return container;
}
}
/// <devdoc>
/// This property returns the default services that are implemented directly on this IServiceContainer.
/// the default implementation of this property is to return the IServiceContainer and ServiceContainer
/// types. You may override this proeprty and return your own types, modifying the default behavior
/// of GetService.
/// </devdoc>
protected virtual Type[] DefaultServices {
get {
return _defaultServices;
}
}
/// <devdoc>
/// Our collection of services. The service collection is demand
/// created here.
/// </devdoc>
private ServiceCollection<object> Services {
get {
if (services == null) {
services = new ServiceCollection<object>();
}
return services;
}
}
/// <devdoc>
/// Adds the given service to the service container.
/// </devdoc>
public void AddService(Type serviceType, object serviceInstance) {
AddService(serviceType, serviceInstance, false);
}
/// <devdoc>
/// Adds the given service to the service container.
/// </devdoc>
public virtual void AddService(Type serviceType, object serviceInstance, bool promote) {
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "Adding service (instance) " + serviceType.Name + ". Promoting: " + promote.ToString());
if (promote) {
IServiceContainer container = Container;
if (container != null) {
Debug.Indent();
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "Promoting to container");
Debug.Unindent();
container.AddService(serviceType, serviceInstance, promote);
return;
}
}
// We're going to add this locally. Ensure that the service instance
// is correct.
//
if (serviceType == null) throw new ArgumentNullException("serviceType");
if (serviceInstance == null) throw new ArgumentNullException("serviceInstance");
if (!(serviceInstance is ServiceCreatorCallback) && !serviceInstance.GetType().IsCOMObject && !serviceType.IsAssignableFrom(serviceInstance.GetType())) {
throw new ArgumentException(SR.GetString(SR.ErrorInvalidServiceInstance, serviceType.FullName));
}
if (Services.ContainsKey(serviceType)) {
throw new ArgumentException(SR.GetString(SR.ErrorServiceExists, serviceType.FullName), "serviceType");
}
Services[serviceType] = serviceInstance;
}
/// <devdoc>
/// Adds the given service to the service container.
/// </devdoc>
public void AddService(Type serviceType, ServiceCreatorCallback callback) {
AddService(serviceType, callback, false);
}
/// <devdoc>
/// Adds the given service to the service container.
/// </devdoc>
public virtual void AddService(Type serviceType, ServiceCreatorCallback callback, bool promote) {
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "Adding service (callback) " + serviceType.Name + ". Promoting: " + promote.ToString());
if (promote) {
IServiceContainer container = Container;
if (container != null) {
Debug.Indent();
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "Promoting to container");
Debug.Unindent();
container.AddService(serviceType, callback, promote);
return;
}
}
// We're going to add this locally. Ensure that the service instance
// is correct.
//
if (serviceType == null) throw new ArgumentNullException("serviceType");
if (callback == null) throw new ArgumentNullException("callback");
if (Services.ContainsKey(serviceType)) {
throw new ArgumentException(SR.GetString(SR.ErrorServiceExists, serviceType.FullName), "serviceType");
}
Services[serviceType] = callback;
}
/// <devdoc>
/// Disposes this service container. This also walks all instantiated services within the container
/// and disposes any that implement IDisposable, and clears the service list.
/// </devdoc>
public void Dispose() {
Dispose(true);
}
/// <devdoc>
/// Disposes this service container. This also walks all instantiated services within the container
/// and disposes any that implement IDisposable, and clears the service list.
/// </devdoc>
protected virtual void Dispose(bool disposing) {
if (disposing) {
ServiceCollection<object> serviceCollection = services;
services = null;
if (serviceCollection != null) {
foreach(object o in serviceCollection.Values) {
if (o is IDisposable) {
((IDisposable)o).Dispose();
}
}
}
}
}
/// <devdoc>
/// Retrieves the requested service.
/// </devdoc>
public virtual object GetService(Type serviceType) {
object service = null;
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "Searching for service " + serviceType.Name);
Debug.Indent();
// Try locally. We first test for services we
// implement and then look in our service collection.
//
Type[] defaults = DefaultServices;
for (int idx = 0; idx < defaults.Length; idx++) {
if (serviceType.IsEquivalentTo(defaults[idx])) {
service = this;
break;
}
}
if (service == null) {
Services.TryGetValue(serviceType, out service);
}
// Is the service a creator delegate?
//
if (service is ServiceCreatorCallback) {
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "Encountered a callback. Invoking it");
service = ((ServiceCreatorCallback)service)(this, serviceType);
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "Callback return object: " + (service == null ? "(null)" : service.ToString()));
if (service != null && !service.GetType().IsCOMObject && !serviceType.IsAssignableFrom(service.GetType())) {
// Callback passed us a bad service. NULL it, rather than throwing an exception.
// Callers here do not need to be prepared to handle bad callback implemetations.
Debug.Fail("Object " + service.GetType().Name + " was returned from a service creator callback but it does not implement the registered type of " + serviceType.Name);
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "**** Object does not implement service interface");
service = null;
}
// And replace the callback with our new service.
//
Services[serviceType] = service;
}
if (service == null && parentProvider != null) {
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "Service unresolved. Trying parent");
service = parentProvider.GetService(serviceType);
}
#if DEBUG
if (TRACESERVICE.TraceVerbose && service == null) {
Debug.WriteLine("******************************************");
Debug.WriteLine("FAILED to resolve service " + serviceType.Name);
Debug.WriteLine("AT: " + Environment.StackTrace);
Debug.WriteLine("******************************************");
}
#endif
Debug.Unindent();
return service;
}
/// <devdoc>
/// Removes the given service type from the service container.
/// </devdoc>
public void RemoveService(Type serviceType) {
RemoveService(serviceType, false);
}
/// <devdoc>
/// Removes the given service type from the service container.
/// </devdoc>
public virtual void RemoveService(Type serviceType, bool promote) {
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "Removing service: " + serviceType.Name + ", Promote: " + promote.ToString());
if (promote) {
IServiceContainer container = Container;
if (container != null) {
Debug.Indent();
Debug.WriteLineIf(TRACESERVICE.TraceVerbose, "Invoking parent container");
Debug.Unindent();
container.RemoveService(serviceType, promote);
return;
}
}
// We're going to remove this from our local list.
//
if (serviceType == null) throw new ArgumentNullException("serviceType");
Services.Remove(serviceType);
}
/// <summary>
/// Use this collection to store mapping from the Type of a service to the object that provides it in a way
/// that is aware of embedded types. The comparer for this collection will call Type.IsEquivalentTo(...)
/// instead of doing a reference comparison which will fail in type embedding scenarios. To speed the lookup
/// performance we will use hash code of Type.FullName.
/// </summary>
/// <typeparam name="T"></typeparam>
private sealed class ServiceCollection<T> : Dictionary<Type, T> {
static EmbeddedTypeAwareTypeComparer serviceTypeComparer = new EmbeddedTypeAwareTypeComparer();
private sealed class EmbeddedTypeAwareTypeComparer : IEqualityComparer<Type> {
#region IEqualityComparer<Type> Members
public bool Equals(Type x, Type y) {
return x.IsEquivalentTo(y);
}
public int GetHashCode(Type obj) {
return obj.FullName.GetHashCode();
}
#endregion
}
public ServiceCollection() : base(serviceTypeComparer) {
}
}
}
}
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