pub fn range_type(start: &str) -> Option<usize>Expand description
Port of range_type(char *start, int len) from Src/pattern.c:1148. Looks up the
integer code for a POSIX character class name (e.g. “alpha” → 1).
Returns None for unknown names.
C signature takes a (char *start, int len) non-NUL-terminated
substring; Rust’s &str carries the length implicitly, so the
two-arg C shape collapses to a single arg. Param name start
matches C verbatim (Rule E).