Function strip_system_time_as_of

nodedb-sql/src/parser/preprocess/temporal.rs:125–145

Match `FOR SYSTEM_TIME AS OF ` case-insensitively and strip it.

(sql: &str)

/// Match `FOR SYSTEM_TIME AS OF <integer>` case-insensitively and strip it.
fn strip_system_time_as_of(sql: &str) -> Result<Option<(String, i64)>, TemporalParseError> {
    let Some(start) = keyword_position_outside_literals(sql, "FOR SYSTEM_TIME") else {
        return Ok(None);
    };
    // Locate `AS OF` after the keyword.
    let after_kw = start + "FOR SYSTEM_TIME".len();
    let tail_upper = sql[after_kw..].to_uppercase();
    let Some(_as_of_rel) = tail_upper.trim_start().strip_prefix("AS OF") else {
        return Err(TemporalParseError(
            "FOR SYSTEM_TIME must be followed by AS OF <ms>".into(),
        ));
    };
    let leading_ws = sql[after_kw..].len() - sql[after_kw..].trim_start().len();
    let as_of_abs = after_kw + leading_ws + "AS OF".len();
    let (ms, end_abs) = parse_trailing_i64(sql, as_of_abs)?;
    let mut out = String::with_capacity(sql.len());
    out.push_str(&sql[..start]);
    out.push(' ');
    out.push_str(&sql[end_abs..]);
    Ok(Some((out, ms)))
}

/// Match `__system_as_of__(<int>)` anywhere in the statement and strip the
/// call by replacing it with the literal `TRUE` so the surrounding