/// <summary>
/// Makes this object non-extensible, which means no new properties can be added to it.
/// </summary>
/// <param name="throwOnError"> <c>true</c> to throw an exception if the object could not
/// be made non-extensible. </param>
/// <returns> <c>true</c> if the operation was successful, <c>false</c> otherwise. </returns>
internal override bool PreventExtensions(bool throwOnError)
{
// Check for revocation.
if (target == null || handler == null)
{
throw new JavaScriptException(ErrorType.TypeError, "Cannot call 'preventExtensions' on a proxy that has been revoked.");
}
// Call the handler, if one exists.
var trap = handler.GetMethod("preventExtensions");
if (trap == null)
{
return(target.PreventExtensions(throwOnError));
}
var result = TypeConverter.ToBoolean(trap.CallLateBound(handler, target));
// Validate.
if (!result)
{
if (throwOnError)
{
throw new JavaScriptException(ErrorType.TypeError, "'preventExtensions' on proxy: trap returned falsish.");
}
return(false);
}
var targetIsExtensible = target.IsExtensible;
if (targetIsExtensible)
{
throw new JavaScriptException(ErrorType.TypeError, "'preventExtensions' on proxy: trap returned truish but the proxy target is extensible.");
}
return(true);
}