Subdivisions

Subdivisions::of('CA');                     // the provinces and territories
Subdivisions::of('BR', 'AC');               // the cities of Acre
Subdivisions::find('Québec', 'CA');         // a Subdivision, or null

A Subdivision has an identifier among its siblings, the code an address carries — QC, or the name where the country has no codes —, a localCode, a name and a localName in the language of its locale — fr for Canada's —, an ISO code where the data have one, the pattern its postal codes start with, and whether it has children.

find() matches a value by identifier, code or name, local ones included, whatever the case: qc, Quebec and Québec are the same province. keys() gives what a subdivision is found by, in lowercase. Each list is indexed by those keys the first time a value is looked up in it, so a lookup among Minas Gerais's 853 cities costs what it costs among Canada's 13 provinces; where two subdivisions of a list share a key, the first one is found. nameIn($locale) gives the local name in its language, the name otherwise.

Lists below the first level are named as commerceguys/addressing names them — BR-AC, or a hash of the parents further down — and found by the parents' identifiers.