Python libtmux accepts filters as keyword arguments whose names encode the operator. That shape cannot survive into the typed API: the field and the operator arrive as untrusted strings, so nothing about their pairing can be checked before the program runs. This parser exists so callers carrying such strings — a CLI flag, a config file, a stored query — have one supported way in, and so the rest of the library never has to accept them.
Everything it rejects is a compile error in the typed form. That is the trade being made explicit rather than hidden: one place where a wrong field name or a text operator on a number becomes a runtime failure, and the type system everywhere else. ## Members - `parse` (method) — Parses {@code field__operator} keys into a conjunction, in the map's iteration order. - `FieldCatalog` (class) — The fields a legacy caller may name.