public void Prepare(MutableType mutableType, EventInfo eventInfo)
{
var eventType = eventInfo.EventHandlerType;
var eventInvoke = eventType.GetMethod("Invoke");
var original = Expression.Field(
new ThisExpression(mutableType),
mutableType.GetField(eventInfo.Name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public));
var broker = Expression.Field(
new ThisExpression(mutableType),
mutableType.AddField(eventInfo.Name + "Broker", eventType));
var addMethod = mutableType.GetOrAddMutableMethod(eventInfo.GetAddMethod(true));
var removeMethod = mutableType.GetOrAddMutableMethod(eventInfo.GetRemoveMethod(true));
var parameters = eventInvoke.GetParameters().Select(ParameterDeclaration.CreateEquivalent);
var invokeMethod = mutableType.AddMethod(
"invoke_" + eventInfo.Name,
MethodAttributes.Private,
eventInvoke.ReturnType,
parameters,
ctx => Expression.Call(broker, eventInvoke, ctx.Parameters.Cast <Expression>()));
var invokeDelegate = new NewDelegateExpression(eventType, new ThisExpression(mutableType.UnderlyingSystemType), invokeMethod);
addMethod.SetBody(
ctx => Expression.Block(
Expression.IfThen(
Expression.Equal(broker, Expression.Constant(null, eventType)),
Expression.Call(ctx.This, new NonVirtualCallMethodInfoAdapter(addMethod.UnderlyingSystemMethodInfo), invokeDelegate)),
Expression.Assign(
broker,
Expression.Convert(Expression.Call(null, s_combineMethod, new Expression[] { broker, ctx.Parameters.Single() }), eventType))));
removeMethod.SetBody(
ctx => Expression.Block(
Expression.IfThen(
Expression.Equal(broker, Expression.Constant(null, eventType)),
Expression.Call(ctx.This, new NonVirtualCallMethodInfoAdapter(addMethod.UnderlyingSystemMethodInfo), invokeDelegate)),
Expression.Assign(
broker,
Expression.Convert(Expression.Call(null, s_combineMethod, new Expression[] { broker, ctx.Parameters.Single() }), eventType))));
}