private static JsFunction WrapDelegate(Delegate @delegate)
{
var builder = new Builder();
builder.AddRuntimeParameter();
builder.AddThisParameter(typeof(object));
builder.AddParameter(typeof(JsObject), "callee");
var argumentsParameter = builder.AddParameter(typeof(object[]), "arguments");
var method = @delegate.Method;
var arguments = new List<Expression>();
var parameters = method.GetParameters();
bool skipFirst = false;
if (parameters.Length > 0 && typeof(JsGlobal).IsAssignableFrom(parameters[0].ParameterType))
{
skipFirst = true;
arguments.Add(builder.Global);
}
int index = 0;
foreach (var parameter in parameters)
{
// Skip over the global parameter.
if (skipFirst)
{
skipFirst = false;
continue;
}
// Get the argument from the array, or undefined there is none.
Expression argument = Expression.Condition(
Expression.GreaterThan(
Expression.ArrayLength(argumentsParameter),
Expression.Constant(index)
),
Expression.ArrayAccess(
argumentsParameter,
Expression.Constant(index)
),
Expression.Field(null, typeof(JsUndefined).GetField("Instance")),
typeof(object)
);
// Add the argument to the list.
arguments.Add(builder.Marshal(argument, parameter.ParameterType));
// Move on to the next argument.
index++;
}
// Call the delegate.
builder.AddStatement(builder.UnMarshalReturn(
Expression.Invoke(
Expression.Constant(@delegate),
arguments
),
method.ReturnType
));
return builder.Compile<JsFunction>();
}