/// <summary>
/// Implements an interface method in a duck proxy type using a given type builder.
/// If successful, the implemented method will be added to the given proxy member dictionary.
/// </summary>
/// <param name="proxyType">Type builder for the duck proxy type.</param>
/// <param name="proxyMembers">Dictionary of members of the proxy type.</param>
/// <param name="duckField">Field that holds a reference to the duck object to forward calls to.</param>
/// <param name="interfaceMethod">The interface method to implement.</param>
private void ImplementMethod(TypeBuilder proxyType, ProxyMemberDictionary proxyMembers, FieldInfo duckField, MethodInfo interfaceMethod)
{
MethodInfo duckMethod = FindDuckMethod(interfaceMethod);
if (duckMethod == null)
{
throw new NotImplementedException("Duck type does not implement a method named \"" + interfaceMethod.Name + "\" with the same parameters and return type.");
}
ParameterInfo[] interfaceMethodParameters = interfaceMethod.GetParameters();
ParameterInfo[] duckMethodParameters = duckMethod.GetParameters();
MethodBuilder proxyMethod = proxyType.DefineMethod(interfaceMethod.Name, MethodAttributes.Public | MethodAttributes.Virtual | MethodAttributes.Final, CallingConventions.HasThis, interfaceMethod.ReturnType, GetParameterTypes(interfaceMethodParameters));
ILGenerator proxyMethodIL = proxyMethod.GetILGenerator();
// Emit IL to load the proxy instance, then load the value of its duck field
proxyMethodIL.Emit(OpCodes.Ldarg_0);
proxyMethodIL.Emit(OpCodes.Ldfld, duckField);
// Emit IL to load method arguments
for (int i = 0; i < interfaceMethodParameters.Length; i++)
{
// Emit IL to load the argument
proxyMethodIL.Emit(OpCodes.Ldarg, i + 1);
// Emit IL to cast the argument if necessary
DuckTyping.EmitCastIL(proxyMethodIL, duckMethodParameters[i].ParameterType, interfaceMethodParameters[i].ParameterType);
}
// Emit IL to call the method
proxyMethodIL.Emit(OpCodes.Callvirt, duckMethod);
// If we are returning something...
if (duckMethod.ReturnType != typeof(void))
{
// Emit IL to cast the return value if necessary
DuckTyping.EmitCastIL(proxyMethodIL, interfaceMethod.ReturnType, duckMethod.ReturnType);
}
// Emit IL to return.
proxyMethodIL.Emit(OpCodes.Ret);
// Add proxy method to proxy member dictionary
// (This is so that any associated properties or events can refer to it later)
proxyMembers.Add(duckMethod, proxyMethod);
}
/// <summary>
/// Implements the method of the proxy type that invokes the delegate given in its constructor.
/// </summary>
/// <param name="proxyType">Type builder to define the invoke method in.</param>
/// <param name="duckDelegateField">Field that stores a reference to the delegate to call.</param>
/// <returns>The implemented invoke method.</returns>
private MethodBuilder ImplementInvokeMethod(TypeBuilder proxyType, FieldInfo duckDelegateField)
{
MethodInfo variantMethod = m_ToDelegateType.GetMethod("Invoke");
MethodInfo duckMethod = m_FromDelegateType.GetMethod("Invoke");
ParameterInfo[] variantMethodParameters = variantMethod.GetParameters();
ParameterInfo[] duckMethodParameters = duckMethod.GetParameters();
MethodBuilder proxyMethod = proxyType.DefineMethod("Invoke", MethodAttributes.Public | MethodAttributes.HideBySig, CallingConventions.HasThis, variantMethod.ReturnType, GetParameterTypes(variantMethodParameters));
ILGenerator proxyMethodIL = proxyMethod.GetILGenerator();
// Emit IL to load the proxy instance, then load the value of its duck delegate field
proxyMethodIL.Emit(OpCodes.Ldarg_0);
proxyMethodIL.Emit(OpCodes.Ldfld, duckDelegateField);
// Emit IL to load method arguments
for (int i = 0; i < variantMethodParameters.Length; i++)
{
// Emit IL to load the argument
proxyMethodIL.Emit(OpCodes.Ldarg, i + 1);
// Emit IL to cast the argument if necessary
DuckTyping.EmitCastIL(proxyMethodIL, duckMethodParameters[i].ParameterType, variantMethodParameters[i].ParameterType);
}
// Emit IL to call the delegate
proxyMethodIL.Emit(OpCodes.Callvirt, duckMethod);
// If we are returning something...
if (duckMethod.ReturnType != typeof(void))
{
// Emit IL to cast the return value if necessary
DuckTyping.EmitCastIL(proxyMethodIL, variantMethod.ReturnType, duckMethod.ReturnType);
}
// Emit IL to return.
proxyMethodIL.Emit(OpCodes.Ret);
return(proxyMethod);
}
/// <summary>
/// Implements an interface event in a duck proxy type using a given type builder.
/// If successful, the implemented event will be added to the given proxy member dictionary.
/// </summary>
/// <param name="proxyType">Type builder for the duck proxy type.</param>
/// <param name="proxyMembers">Dictionary of members of the proxy type.</param>
/// <param name="duckField">Field that holds a reference to the duck object to forward calls to.</param>
/// <param name="constructorIL">IL generator to use to add code to the constructor if necessary.</param>
/// <param name="interfaceEvent">The interface event to implement.</param>
private void ImplementEvent(TypeBuilder proxyType, ProxyMemberDictionary proxyMembers, FieldInfo duckField, ILGenerator constructorIL, EventInfo interfaceEvent)
{
EventInfo duckEvent = FindDuckEvent(interfaceEvent);
if (duckEvent == null)
{
throw new NotImplementedException("Duck type does not implement an event named \"" + interfaceEvent.Name + "\" with the same event handler type.");
}
EventBuilder proxyEvent = proxyType.DefineEvent(interfaceEvent.Name, EventAttributes.None, interfaceEvent.EventHandlerType);
Type interfaceEventHandlerType = interfaceEvent.EventHandlerType;
Type duckEventHandlerType = duckEvent.EventHandlerType;
// Define event add method
MethodBuilder addMethod = proxyType.DefineMethod("add_" + interfaceEvent.Name, MethodAttributes.Public | MethodAttributes.Virtual | MethodAttributes.Final, CallingConventions.HasThis, typeof(void), new Type[] { interfaceEventHandlerType });
ILGenerator addMethodIL = addMethod.GetILGenerator();
// Define event remove method
MethodBuilder removeMethod = proxyType.DefineMethod("remove_" + interfaceEvent.Name, MethodAttributes.Public | MethodAttributes.Virtual | MethodAttributes.Final, CallingConventions.HasThis, typeof(void), new Type[] { interfaceEventHandlerType });
ILGenerator removeMethodIL = removeMethod.GetILGenerator();
if (interfaceEventHandlerType == duckEventHandlerType)
{
// If the event handler types are the same, we can just forward calls to add and remove like normal.
MethodInfo duckAddMethod = duckEvent.GetAddMethod();
if (!duckAddMethod.IsStatic)
{
addMethodIL.Emit(OpCodes.Ldarg_0);
addMethodIL.Emit(OpCodes.Ldfld, duckField);
addMethodIL.Emit(OpCodes.Ldarg_1);
addMethodIL.Emit(OpCodes.Callvirt, duckAddMethod);
}
else
{
addMethodIL.Emit(OpCodes.Ldarg_1);
addMethodIL.Emit(OpCodes.Call, duckAddMethod);
}
MethodInfo duckRemoveMethod = duckEvent.GetRemoveMethod();
if (!duckRemoveMethod.IsStatic)
{
removeMethodIL.Emit(OpCodes.Ldarg_0);
removeMethodIL.Emit(OpCodes.Ldfld, duckField);
removeMethodIL.Emit(OpCodes.Ldarg_1);
removeMethodIL.Emit(OpCodes.Callvirt, duckRemoveMethod);
}
else
{
removeMethodIL.Emit(OpCodes.Ldarg_1);
removeMethodIL.Emit(OpCodes.Call, duckRemoveMethod);
}
}
else
{
// If the event handler types are different, we need some special behavior. Specifically, the event handlers
// added using the interface are kept as a seperate multicast delegate in the proxy class and an event handler
// is added to the duck that calls the proxy event delegate.
// Define the event multicast delegate field
FieldBuilder eventHandlerField = proxyType.DefineField(interfaceEvent.Name, interfaceEventHandlerType, FieldAttributes.Private);
// Implement the add method
addMethodIL.Emit(OpCodes.Ldarg_0);
addMethodIL.Emit(OpCodes.Ldarg_0);
addMethodIL.Emit(OpCodes.Ldfld, eventHandlerField);
addMethodIL.Emit(OpCodes.Ldarg_1);
addMethodIL.Emit(OpCodes.Call, typeof(Delegate).GetMethod("Combine", new Type[] { typeof(Delegate), typeof(Delegate) }));
addMethodIL.Emit(OpCodes.Castclass, interfaceEventHandlerType);
addMethodIL.Emit(OpCodes.Stfld, eventHandlerField);
// Implement the remove method
removeMethodIL.Emit(OpCodes.Ldarg_0);
removeMethodIL.Emit(OpCodes.Ldarg_0);
removeMethodIL.Emit(OpCodes.Ldfld, eventHandlerField);
removeMethodIL.Emit(OpCodes.Ldarg_1);
removeMethodIL.Emit(OpCodes.Call, typeof(Delegate).GetMethod("Remove", new Type[] { typeof(Delegate), typeof(Delegate) }));
removeMethodIL.Emit(OpCodes.Castclass, interfaceEventHandlerType);
removeMethodIL.Emit(OpCodes.Stfld, eventHandlerField);
// Set some local variables for later use...
MethodInfo interfaceInvokeMethod = interfaceEventHandlerType.GetMethod("Invoke");
Type[] interfaceInvokeMethodParameterTypes = GetParameterTypes(interfaceInvokeMethod.GetParameters());
MethodInfo duckInvokeMethod = duckEventHandlerType.GetMethod("Invoke");
Type[] duckInvokeMethodParameterTypes = GetParameterTypes(duckInvokeMethod.GetParameters());
// Define the method that will serve as an event handler to the duck which will invoke the proxy's delegate
MethodBuilder proxyInvokeMethod = proxyType.DefineMethod("Invoke" + interfaceEvent.Name, MethodAttributes.Private | MethodAttributes.Virtual | MethodAttributes.Final, CallingConventions.HasThis, duckInvokeMethod.ReturnType, duckInvokeMethodParameterTypes);
ILGenerator proxyInvokeMethodIL = proxyInvokeMethod.GetILGenerator();
// First, check if the proxy event handler is null
Label ifEventHandlerIsNullLabel = proxyInvokeMethodIL.DefineLabel();
proxyInvokeMethodIL.Emit(OpCodes.Ldarg_0);
proxyInvokeMethodIL.Emit(OpCodes.Ldfld, eventHandlerField);
proxyInvokeMethodIL.Emit(OpCodes.Ldnull);
proxyInvokeMethodIL.Emit(OpCodes.Ceq);
proxyInvokeMethodIL.Emit(OpCodes.Brtrue_S, ifEventHandlerIsNullLabel);
// If the proxy event handler is not null, invoke it
proxyInvokeMethodIL.Emit(OpCodes.Ldarg_0);
proxyInvokeMethodIL.Emit(OpCodes.Ldfld, eventHandlerField);
for (int i = 0; i < interfaceInvokeMethodParameterTypes.Length; i++)
{
proxyInvokeMethodIL.Emit(OpCodes.Ldarg, i + 1);
DuckTyping.EmitCastIL(proxyInvokeMethodIL, interfaceInvokeMethodParameterTypes[i], duckInvokeMethodParameterTypes[i]);
}
proxyInvokeMethodIL.Emit(OpCodes.Callvirt, interfaceInvokeMethod);
// If the proxy event handler is null, execution jumps here
proxyInvokeMethodIL.MarkLabel(ifEventHandlerIsNullLabel);
// Return
proxyInvokeMethodIL.Emit(OpCodes.Ret);
// Add code to the constructor to add the event handler to the duck.
MethodInfo duckAddMethod = duckEvent.GetAddMethod();
if (!duckAddMethod.IsStatic)
{
constructorIL.Emit(OpCodes.Ldarg_0);
constructorIL.Emit(OpCodes.Ldfld, duckField);
}
constructorIL.Emit(OpCodes.Ldarg_0);
constructorIL.Emit(OpCodes.Ldftn, proxyInvokeMethod);
constructorIL.Emit(OpCodes.Newobj, duckEventHandlerType.GetConstructor(new Type[] { typeof(object), typeof(IntPtr) }));
if (!duckAddMethod.IsStatic)
{
constructorIL.Emit(OpCodes.Callvirt, duckAddMethod);
}
else
{
constructorIL.Emit(OpCodes.Call, duckAddMethod);
}
}
// Finish add method and set it for the event
addMethodIL.Emit(OpCodes.Ret);
proxyEvent.SetAddOnMethod(addMethod);
// Finish remove method and set it for the event
removeMethodIL.Emit(OpCodes.Ret);
proxyEvent.SetRemoveOnMethod(removeMethod);
// Other associated methods appear before the event in the member array; thus, they have already been
// defined and implemented. The proxy member dictionary is used to refer to these.
MethodInfo raiseMethod = duckEvent.GetRaiseMethod();
if (raiseMethod != null)
{
proxyEvent.SetRaiseMethod((MethodBuilder)(proxyMembers[raiseMethod]));
}
MethodInfo[] otherDuckMethods = duckEvent.GetOtherMethods();
foreach (MethodInfo otherDuckMethod in otherDuckMethods)
{
if (proxyMembers.ContainsKey(otherDuckMethod))
{
proxyEvent.AddOtherMethod((MethodBuilder)(proxyMembers[otherDuckMethod]));
}
}
// Add proxy event to the proxy member dictionary
// (This is not really necessary, but good to keep things consistent)
// if (proxyMembers != null) proxyMembers[duckEvent] = proxyEvent;
// For some reason, EventBuilder does not inherit MemberInfo, so it cannot be added.
}
/// <summary>
/// Implements an interface method in a duck proxy type using a given type builder.
/// If successful, the implemented method will be added to the given proxy member dictionary.
/// </summary>
/// <param name="proxyType">Type builder for the duck proxy type.</param>
/// <param name="proxyMembers">Dictionary of members of the proxy type.</param>
/// <param name="duckField">Field that holds a reference to the duck object to forward calls to.</param>
/// <param name="constructorIL">IL generator to use to add code to the constructor if necessary.</param>
/// <param name="interfaceMethod">The interface method to implement.</param>
private void ImplementMethod(TypeBuilder proxyType, ProxyMemberDictionary proxyMembers, FieldInfo duckField, ILGenerator constructorIL, MethodInfo interfaceMethod)
{
MethodInfo duckMethod = FindDuckMethod(interfaceMethod);
if (duckMethod == null)
{
throw new NotImplementedException("Duck type does not implement a method named \"" + interfaceMethod.Name + "\" with compatible parameters and return type.");
}
if (!duckMethod.IsSpecialName || (!duckMethod.Name.StartsWith("add_") && !duckMethod.Name.StartsWith("remove_")))
{
ParameterInfo[] interfaceMethodParameters = interfaceMethod.GetParameters();
ParameterInfo[] duckMethodParameters = duckMethod.GetParameters();
MethodBuilder proxyMethod = proxyType.DefineMethod(interfaceMethod.Name, MethodAttributes.Public | MethodAttributes.Virtual | MethodAttributes.Final, CallingConventions.HasThis, interfaceMethod.ReturnType, GetParameterTypes(interfaceMethodParameters));
GenericTypeParameterBuilder[] genericParameters;
if (interfaceMethod.IsGenericMethodDefinition)
{
Type[] interfaceMethodGenericArguments = interfaceMethod.GetGenericArguments();
string[] genericParameterNames = new string[interfaceMethodGenericArguments.Length];
for (int i = 0; i < interfaceMethodGenericArguments.Length; i++)
{
genericParameterNames[i] = interfaceMethodGenericArguments[i].Name;
}
genericParameters = proxyMethod.DefineGenericParameters(genericParameterNames);
}
else
{
genericParameters = new GenericTypeParameterBuilder[0];
}
ILGenerator proxyMethodIL = proxyMethod.GetILGenerator();
// Emit IL to load the duck object if the method is not static
if (!duckMethod.IsStatic)
{
// Emit IL to load the proxy instance, then load the value of its duck field
proxyMethodIL.Emit(OpCodes.Ldarg_0);
proxyMethodIL.Emit(OpCodes.Ldfld, duckField);
}
// Emit IL to load method arguments
for (int i = 0; i < interfaceMethodParameters.Length; i++)
{
// Emit IL to load the argument
proxyMethodIL.Emit(OpCodes.Ldarg, 1 + i);
// Emit IL to cast the argument if necessary
DuckTyping.EmitCastIL(proxyMethodIL, duckMethodParameters[i].ParameterType, interfaceMethodParameters[i].ParameterType);
}
MethodInfo methodToCall;
if (!duckMethod.IsGenericMethodDefinition)
{
methodToCall = duckMethod;
}
else
{
methodToCall = duckMethod.MakeGenericMethod((Type[])(genericParameters));
}
// Emit IL to call the method
if (!duckMethod.IsStatic)
{
proxyMethodIL.Emit(OpCodes.Callvirt, methodToCall);
}
else
{
proxyMethodIL.Emit(OpCodes.Call, methodToCall);
}
// If we are returning something...
if (duckMethod.ReturnType != typeof(void))
{
// Emit IL to cast the return value if necessary
DuckTyping.EmitCastIL(proxyMethodIL, interfaceMethod.ReturnType, duckMethod.ReturnType);
}
// Emit IL to return.
proxyMethodIL.Emit(OpCodes.Ret);
// Add proxy method to proxy member dictionary
// (This is so that any associated properties or events can refer to it later)
if (proxyMembers != null)
{
proxyMembers[duckMethod] = proxyMethod;
}
}
}
