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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Runtime.Serialization;
namespace System
{
public abstract partial class Delegate : ICloneable, ISerializable
{
public virtual object Clone() => MemberwiseClone();
[return: NotNullIfNotNull(nameof(a))]
[return: NotNullIfNotNull(nameof(b))]
public static Delegate? Combine(Delegate? a, Delegate? b)
{
if (a is null)
return b;
return a.CombineImpl(b);
}
public static Delegate? Combine(params Delegate?[]? delegates) =>
Combine((ReadOnlySpan<Delegate?>)delegates);
/// <summary>
/// Concatenates the invocation lists of an span of delegates.
/// </summary>
/// <param name="delegates">The span of delegates to combine.</param>
/// <returns>
/// A new delegate with an invocation list that concatenates the invocation lists of the delegates in the <paramref name="delegates"/> span.
/// Returns <see langword="null" /> if <paramref name="delegates"/> is <see langword="null" />,
/// if <paramref name="delegates"/> contains zero elements, or if every entry in <paramref name="delegates"/> is <see langword="null" />.
/// </returns>
public static Delegate? Combine(/*params*/ ReadOnlySpan<Delegate?> delegates)
{
Delegate? d = null;
if (!delegates.IsEmpty)
{
d = delegates[0];
for (int i = 1; i < delegates.Length; i++)
{
d = Combine(d, delegates[i]);
}
}
return d;
}
// V2 api: Creates open or closed delegates to static or instance methods - relaxed signature checking allowed.
public static Delegate CreateDelegate(Type type, object? firstArgument, MethodInfo method) => CreateDelegate(type, firstArgument, method, throwOnBindFailure: true)!;
// V1 api: Creates open delegates to static or instance methods - relaxed signature checking allowed.
public static Delegate CreateDelegate(Type type, MethodInfo method) => CreateDelegate(type, method, throwOnBindFailure: true)!;
// V1 api: Creates closed delegates to instance methods only, relaxed signature checking disallowed.
[RequiresUnreferencedCode("The target method might be removed")]
public static Delegate CreateDelegate(Type type, object target, string method) => CreateDelegate(type, target, method, ignoreCase: false, throwOnBindFailure: true)!;
[RequiresUnreferencedCode("The target method might be removed")]
public static Delegate CreateDelegate(Type type, object target, string method, bool ignoreCase) => CreateDelegate(type, target, method, ignoreCase, throwOnBindFailure: true)!;
// V1 api: Creates open delegates to static methods only, relaxed signature checking disallowed.
public static Delegate CreateDelegate(Type type, [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] Type target, string method) => CreateDelegate(type, target, method, ignoreCase: false, throwOnBindFailure: true)!;
public static Delegate CreateDelegate(Type type, [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] Type target, string method, bool ignoreCase) => CreateDelegate(type, target, method, ignoreCase, throwOnBindFailure: true)!;
#if !NATIVEAOT
protected virtual Delegate CombineImpl(Delegate? d) => throw new MulticastNotSupportedException(SR.Multicast_Combine);
protected virtual Delegate? RemoveImpl(Delegate d) => d.Equals(this) ? null : this;
public virtual Delegate[] GetInvocationList() => new Delegate[] { this };
/// <summary>
/// Gets a value that indicates whether the <see cref="Delegate"/> has a single invocation target.
/// </summary>
/// <value>true if the <see cref="Delegate"/> has a single invocation target.</value>
public bool HasSingleTarget => Unsafe.As<MulticastDelegate>(this).HasSingleTarget;
#endif
/// <summary>
/// Gets an enumerator for the invocation targets of this delegate.
/// </summary>
/// <remarks>
/// This returns a <see cref="InvocationListEnumerator{TDelegate}"/>" /> that follows the IEnumerable pattern and
/// thus can be used in a C# 'foreach' statements to retrieve the invocation targets of this delegate without allocations.
/// The order of the delegates returned by the enumerator is the same order in which the current delegate invokes the methods that those delegates represent.
/// The method returns an empty enumerator for null delegate.
/// </remarks>
public static System.Delegate.InvocationListEnumerator<TDelegate> EnumerateInvocationList<TDelegate>(TDelegate? d) where TDelegate : System.Delegate
=> new InvocationListEnumerator<TDelegate>(Unsafe.As<MulticastDelegate>(d));
/// <summary>
/// Provides an enumerator for the invocation list of a delegate.
/// </summary>
/// <typeparam name="TDelegate">Delegate type being enumerated.</typeparam>
public struct InvocationListEnumerator<TDelegate> where TDelegate : System.Delegate
{
private readonly MulticastDelegate? _delegate;
private int _index;
private TDelegate? _current;
internal InvocationListEnumerator(MulticastDelegate? d)
{
_delegate = d;
_index = -1;
}
/// <summary>
/// Implements the IEnumerator pattern.
/// </summary>
public TDelegate Current
{
get => _current!;
}
/// <summary>
/// Implements the IEnumerator pattern.
/// </summary>
public bool MoveNext()
{
int index = _index + 1;
if ((_current = Unsafe.As<TDelegate>(_delegate?.TryGetAt(index))) == null)
{
return false;
}
_index = index;
return true;
}
/// <summary>
/// Implement IEnumerable.GetEnumerator() to return 'this' as the IEnumerator
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)] // Only here to make foreach work
public System.Delegate.InvocationListEnumerator<TDelegate> GetEnumerator() => this;
}
public object? DynamicInvoke(params object?[]? args)
{
return DynamicInvokeImpl(args);
}
[Obsolete(Obsoletions.LegacyFormatterImplMessage, DiagnosticId = Obsoletions.LegacyFormatterImplDiagId, UrlFormat = Obsoletions.SharedUrlFormat)]
[EditorBrowsable(EditorBrowsableState.Never)]
public virtual void GetObjectData(SerializationInfo info, StreamingContext context) => throw new PlatformNotSupportedException();
public MethodInfo Method => GetMethodImpl();
public static Delegate? Remove(Delegate? source, Delegate? value)
{
if (source == null)
return null;
if (value == null)
return source;
if (!InternalEqualTypes(source, value))
throw new ArgumentException(SR.Arg_DlgtTypeMis);
return source.RemoveImpl(value);
}
public static Delegate? RemoveAll(Delegate? source, Delegate? value)
{
Delegate? newDelegate;
do
{
newDelegate = source;
source = Remove(source, value);
}
while (newDelegate != source);
return newDelegate;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool operator ==(Delegate? d1, Delegate? d2)
{
// Test d2 first to allow branch elimination when inlined for null checks (== null)
// so it can become a simple test
if (d2 is null)
{
return d1 is null;
}
return ReferenceEquals(d2, d1) ? true : d2.Equals((object?)d1);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool operator !=(Delegate? d1, Delegate? d2)
{
// Test d2 first to allow branch elimination when inlined for not null checks (!= null)
// so it can become a simple test
if (d2 is null)
{
return d1 is not null;
}
return ReferenceEquals(d2, d1) ? false : !d2.Equals(d1);
}
}
}
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