def detect_format()

in python/moz/l10n/formats/__init__.py [0:0]

• 53 lines of code
• 27 McCabe index (conditional complexity)

def detect_format(name: str | None, source: bytes | str | None = None) -> Format | None:
    """
    Detect the format of the input based on its file extension
    and/or contents.

    Returns a `Format` enum value, or `None` if the input is not recognized.
    Without `source`, JSON and XML based formats are
    only recognized if they have a distinctive file extension.
    """
    if not name:
        ext = None
    else:
        _, ext = splitext(name)
        if ext == ".dtd":
            return Format.dtd
        elif ext == ".ftl":
            return Format.fluent
        elif ext == ".inc":
            return Format.inc
        elif ext == ".ini":
            return Format.ini
        elif ext == ".properties":
            return Format.properties
        elif ext in {".po", ".pot"}:
            return Format.po
        elif ext in {".xlf", ".xliff"}:
            return Format.xliff

    if source is None:
        return None

    # Try parsing as JSON first, unless we're pretty sure it's XML
    if ext != ".xml":
        try:
            json: dict[str, Any] = loads(source)
            if not is_object_of_strings(json):
                return None
            if all(is_webext_message(m) for m in json.values()):
                return Format.webext
            return Format.plain_json
        except JSONDecodeError:
            pass

        try:
            json = json_linecomment_loads(source)
            if is_object_of_strings(json) and all(
                is_webext_message(m) for m in json.values()
            ):
                return Format.webext
            return None
        except JSONDecodeError:
            pass

    # Let's presume the input is XML and look at its root node.
    try:
        from lxml.etree import LxmlError, iterparse

        bs = source.encode() if isinstance(source, str) else source
        _, xml_root = next(iterparse(BytesIO(bs), events=("start",)))
        ns = xml_root.nsmap.get(None, None)
        if ns:
            return Format.xliff if ns in xliff_ns else None
        return Format.android if xml_root.tag == "resources" else None
    except ImportError:
        pass
    except LxmlError:
        # Must be separate and after ImportError
        pass

    return None