Function identifier

misc/python/materialize/mzexplore/sql.py:175–218

A version of pg8000.native.identifier (1) that is _ACTUALLY_ compatible with the Postgres code (2). 1. https://github.com/tlocke/pg8000/blob/017959e97751c35a3d58bc8bd5722cee5c10b656/pg8000/converters.py#L739-L761 2. https://github.com/postgres/postgres/blob/b0f7dd915bca6243f3daf52a

(s: str, force_quote: bool = False)

def identifier(s: str, force_quote: bool = False) -> str:
    """
    A version of pg8000.native.identifier (1) that is _ACTUALLY_ compatible with
    the Postgres code (2).

    1. https://github.com/tlocke/pg8000/blob/017959e97751c35a3d58bc8bd5722cee5c10b656/pg8000/converters.py#L739-L761
    2. https://github.com/postgres/postgres/blob/b0f7dd915bca6243f3daf52a81b8d0682a38ee3b/src/backend/utils/adt/ruleutils.c#L11968-L12050
    """
    if not isinstance(s, str):
        raise InterfaceError("identifier must be a str")

    if len(s) == 0:
        raise InterfaceError("identifier must be > 0 characters in length")

    # Look for characters that require quotation.
    def is_alpha(c: str) -> bool:
        return ord(c) >= ord("a") and ord(c) <= ord("z") or c == "_"

    def is_alphanum(c: str) -> bool:
        return is_alpha(c) or ord(c) >= ord("0") and ord(c) <= ord("9")

    quote = not (is_alpha(s[0]))

    for c in s[1:]:
        if not (is_alphanum(c)):
            if c == "\u0000":
                raise InterfaceError(
                    "identifier cannot contain the code zero character"
                )
            quote = True

        if quote:
            break

    # Even if no speciall characters can be found we still want to quote
    # keywords.
    if s.upper() in keywords():
        quote = True

    if quote or force_quote:
        s = s.replace('"', '""')
        return f'"{s}"'
    else:
        return s


@functools.lru_cache(maxsize=1)