/*
 *  call-seq:
 *    ripper#parse
 *
 *  Start parsing and returns the value of the root action.
 */
static VALUE
ripper_parse(VALUE self)
{
    struct parser_params *parser;

    TypedData_Get_Struct(self, struct parser_params, &parser_data_type, parser);
    if (!ripper_initialized_p(parser)) {
        rb_raise(rb_eArgError, "method called for uninitialized object");
    }
    if (!NIL_P(parser->parsing_thread)) {
        if (parser->parsing_thread == rb_thread_current())
            rb_raise(rb_eArgError, "Ripper#parse is not reentrant");
        else
            rb_raise(rb_eArgError, "Ripper#parse is not multithread-safe");
    }
    parser->parsing_thread = rb_thread_current();
    rb_ensure(ripper_parse0, self, ripper_ensure, self);

    return parser->result;
}