Function parse_ident

src/expr/src/scalar/func.rs:2244–2321

transliterated from postgres/src/backend/utils/adt/misc.c

(ident: &'a str, strict: bool)

#[sqlfunc]
// transliterated from postgres/src/backend/utils/adt/misc.c
fn parse_ident<'a>(ident: &'a str, strict: bool) -> Result<ArrayRustType<Cow<'a, str>>, EvalError> {
    fn is_ident_start(c: char) -> bool {
        matches!(c, 'A'..='Z' | 'a'..='z' | '_' | '\u{80}'..=char::MAX)
    }

    fn is_ident_cont(c: char) -> bool {
        matches!(c, '0'..='9' | '$') || is_ident_start(c)
    }

    let mut elems = vec![];
    let buf = &mut LexBuf::new(ident);

    let mut after_dot = false;

    buf.take_while(|ch| ch.is_ascii_whitespace());

    loop {
        let mut missing_ident = true;

        let c = buf.next();

        if c == Some('"') {
            let s = buf.take_while(|ch| !matches!(ch, '"'));

            if buf.next() != Some('"') {
                return Err(EvalError::InvalidIdentifier {
                    ident: ident.into(),
                    detail: Some("String has unclosed double quotes.".into()),
                });
            }
            elems.push(Cow::Borrowed(s));
            missing_ident = false;
        } else if c.map(is_ident_start).unwrap_or(false) {
            buf.prev();
            let s = buf.take_while(is_ident_cont);
            elems.push(Cow::Owned(s.to_ascii_lowercase()));
            missing_ident = false;
        }

        if missing_ident {
            if c == Some('.') {
                return Err(EvalError::InvalidIdentifier {
                    ident: ident.into(),
                    detail: Some("No valid identifier before \".\".".into()),
                });
            } else if after_dot {
                return Err(EvalError::InvalidIdentifier {
                    ident: ident.into(),
                    detail: Some("No valid identifier after \".\".".into()),
                });
            } else {
                return Err(EvalError::InvalidIdentifier {
                    ident: ident.into(),
                    detail: None,
                });
            }
        }