def METHOD_NAME(self):
    config = load_configuration(self.configuration_path)
    if self.case_sensitive:
        self.re_kwargs = {}
    else:
        self.re_kwargs = {'flags': re.IGNORECASE}
    # regex compilation
    self.config = []
    for rule in config:
        self.config.append(rule)
        for field, expression in rule["if"].items():
            if isinstance(expression, str) and expression != '':
                self.config[-1]["if"][field] = re.compile(expression, **self.re_kwargs)