__init__.py 文件源码

def find_lexer_class_by_name(_alias):
    """Lookup a lexer class by alias.

    Like `get_lexer_by_name`, but does not instantiate the class.

    .. versionadded:: 2.2
    """
    if not _alias:
        raise ClassNotFound('no lexer for alias %r found' % _alias)
    # lookup builtin lexers
    for module_name, name, aliases, _, _ in itervalues(LEXERS):
        if _alias.lower() in aliases:
            if name not in _lexer_cache:
                _load_lexers(module_name)
            return _lexer_cache[name]
    # continue with lexers from setuptools entrypoints
    for cls in find_plugin_lexers():
        if _alias.lower() in cls.aliases:
            return cls
    raise ClassNotFound('no lexer for alias %r found' % _alias)