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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.
// See the LICENSE file in the project root for more information.
//
// Activator is an object that contains the Activation (CreateInstance/New)
// methods for late bound support.
//
using System.Diagnostics;
using System.Globalization;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Runtime.Remoting;
using System.Runtime;
using Internal.Reflection.Augments;
namespace System
{
public static class Activator
{
// The following 2 methods and helper class implement the functionality of Activator.CreateInstance<T>()
// This method is the public surface area. It wraps the CreateInstance intrinsic with the appropriate try/catch
// block so that the correct exceptions are generated. Also, it handles the cases where the T type doesn't have
// a default constructor. (Those result in running the ClassWithMissingConstructor's .ctor, which flips the magic
// thread static to cause the CreateInstance<T> method to throw the right exception.)
//
[DebuggerGuidedStepThrough]
public static T CreateInstance<T>()
{
T t = default(T);
bool missingDefaultConstructor = false;
EETypePtr eetype = EETypePtr.EETypePtrOf<T>();
if (!RuntimeHelpers.IsReference<T>())
{
// Early out for valuetypes since we don't support default constructors anyway.
// This lets codegens that expand IsReference<T> optimize away the rest of this code.
}
else if (eetype.ComponentSize != 0)
{
// ComponentSize > 0 indicates an array-like type (e.g. string, array, etc).
// Allocating this using the normal allocator would result in silent heap corruption.
missingDefaultConstructor = true;
}
else if (eetype.IsInterface)
{
// Do not attempt to allocate interface types either
missingDefaultConstructor = true;
}
else
{
bool oldValueOfMissingDefaultCtorMarkerBool = s_createInstanceMissingDefaultConstructor;
try
{
#if PROJECTN
t = CreateInstanceIntrinsic<T>();
DebugAnnotations.PreviousCallContainsDebuggerStepInCode();
#else
t = (T)(RuntimeImports.RhNewObject(eetype));
// Run the default constructor. If the default constructor was missing, codegen
// will expand DefaultConstructorOf to ClassWithMissingConstructor::.ctor
// and we detect that later.
IntPtr defaultConstructor = DefaultConstructorOf<T>();
RawCalliHelper.Call(defaultConstructor, t);
DebugAnnotations.PreviousCallContainsDebuggerStepInCode();
#endif
}
catch (Exception e)
{
throw new TargetInvocationException(e);
}
if (s_createInstanceMissingDefaultConstructor != oldValueOfMissingDefaultCtorMarkerBool)
{
missingDefaultConstructor = true;
// We didn't call the real .ctor (because there wasn't one), but we still allocated
// an uninitialized object. If it has a finalizer, it would run - prevent that.
GC.SuppressFinalize(t);
}
}
if (missingDefaultConstructor)
{
throw new MissingMethodException(SR.Format(SR.MissingConstructor_Name, typeof(T)));
}
return t;
}
[Intrinsic]
private extern static T CreateInstanceIntrinsic<T>();
[Intrinsic]
private static IntPtr DefaultConstructorOf<T>()
{
// Codegens must expand this intrinsic.
// We could implement a fallback with the type loader if we wanted to, but it will be slow and unreliable.
throw new NotSupportedException();
}
[ThreadStatic]
internal static bool s_createInstanceMissingDefaultConstructor;
internal class ClassWithMissingConstructor
{
private ClassWithMissingConstructor()
{
s_createInstanceMissingDefaultConstructor = !s_createInstanceMissingDefaultConstructor;
}
internal static void MissingDefaultConstructorStaticEntryPoint()
{
s_createInstanceMissingDefaultConstructor = !s_createInstanceMissingDefaultConstructor;
}
}
[DebuggerHidden]
[DebuggerStepThrough]
public static object CreateInstance(Type type) => CreateInstance(type, nonPublic: false);
[DebuggerHidden]
[DebuggerStepThrough]
public static object CreateInstance(Type type, bool nonPublic) => ReflectionAugments.ReflectionCoreCallbacks.ActivatorCreateInstance(type, nonPublic);
[DebuggerHidden]
[DebuggerStepThrough]
public static object CreateInstance(Type type, params object[] args) => CreateInstance(type, ConstructorDefault, null, args, null, null);
[DebuggerHidden]
[DebuggerStepThrough]
public static object CreateInstance(Type type, object[] args, object[] activationAttributes) => CreateInstance(type, ConstructorDefault, null, args, null, activationAttributes);
[DebuggerHidden]
[DebuggerStepThrough]
public static object CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, object[] args, CultureInfo culture) => CreateInstance(type, bindingAttr, binder, args, culture, null);
[DebuggerHidden]
[DebuggerStepThrough]
public static object CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, object[] args, CultureInfo culture, object[] activationAttributes)
{
return ReflectionAugments.ReflectionCoreCallbacks.ActivatorCreateInstance(type, bindingAttr, binder, args, culture, activationAttributes);
}
private const BindingFlags ConstructorDefault = BindingFlags.Instance | BindingFlags.Public | BindingFlags.CreateInstance;
public static ObjectHandle CreateInstance(string assemblyName, string typeName)
{
throw new PlatformNotSupportedException(); // https://github.com/dotnet/corefx/issues/30845
}
public static ObjectHandle CreateInstance(string assemblyName,
string typeName,
bool ignoreCase,
BindingFlags bindingAttr,
Binder binder,
object[] args,
CultureInfo culture,
object[] activationAttributes)
{
throw new PlatformNotSupportedException(); // https://github.com/dotnet/corefx/issues/30845
}
public static ObjectHandle CreateInstance(string assemblyName, string typeName, object[] activationAttributes)
{
throw new PlatformNotSupportedException(); // https://github.com/dotnet/corefx/issues/30845
}
public static ObjectHandle CreateInstanceFrom(string assemblyFile, string typeName)
{
throw new PlatformNotSupportedException();
}
public static ObjectHandle CreateInstanceFrom(string assemblyFile,
string typeName,
bool ignoreCase,
BindingFlags bindingAttr,
Binder binder,
object[] args,
CultureInfo culture,
object[] activationAttributes)
{
throw new PlatformNotSupportedException();
}
public static ObjectHandle CreateInstanceFrom(string assemblyFile, string typeName, object[] activationAttributes)
{
throw new PlatformNotSupportedException();
}
}
}
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