Rakuのgrammarを使ってREST風URLをパースする

grammar-rest.p6

# https://docs.perl6.org/language/grammar_tutorial このチュートリアルのコードです

grammar REST {
    token TOP { <slash><subject><slash><command>[<slash><data>]? }

    proto token command {*}
    token command:sym<create> { <sym> }
    token command:sym<retrieve> { <sym> }
    token command:sym<update> { <sym> }
    token command:sym<delete> { <sym> }

    token subject { \w+ }
    token data { .* }
    token slash { \s* '/' \s* }
}

class REST-actions {
    method TOP($/) {
        make {
            subject => $<subject>.Str,
            command => $<command>.Str,
            data => $<data>.made,
            subject-id => $<data>.made[0]
        }
    }
    method data($/) { make $/.split('/') }
}

my $uri = '/product/update/7/notify';
my $rest = REST.parse($uri, actions => REST-actions.new).made;

say $rest<command>; # update                                                                                       say $rest<subject>; # product
say $rest<subject-id>; # 7