Expand description
Output-precedence ranks, derived directly from the parser’s Precedence
ladder (higher binds tighter) so it stays the single source of truth:
reordering or inserting a parser level reranks these automatically, and only
the variant each rank maps to is maintained by hand. They classify the top
operator an expr prints with, so the binary-operator printer can parenthesize
an operand that would otherwise re-associate on reparse. ATOM, the one rank
with no parser counterpart, is layered one above the tightest parser level to
mark the self-delimiting primaries. They never need parens.