Psych::Parser#_native_parse

static VALUE parse(VALUE self, VALUE handler, VALUE yaml, VALUE path)
{
    psych_parser_t * parser;
    struct parse_args pargs;

    TypedData_Get_Struct(self, psych_parser_t, &psych_parser_type, parser);

    if (parser->parsing) {
        rb_raise(rb_const_get(mPsych, rb_intern("Exception")),
                "parser is already parsing, it cannot be reused from a handler callback");
    }
    parser->parsing = 1;

    pargs.psych_parser = parser;
    pargs.self         = self;
    pargs.handler      = handler;
    pargs.yaml         = yaml;
    pargs.path         = path;

    return rb_ensure(parse_body, (VALUE)&pargs, parse_ensure, (VALUE)parser);
}