QuotedCharacter = !("\\E") .
Escape = "p{" CharacterInBracket*:s "}" => [[ s name>class <primitive-class> ]]
- | "P{" CharacterInBracket*:s "}" => [[ s name>class <primitive-class> <negation> ]]
+ | "P{" CharacterInBracket*:s "}" => [[ s name>class <primitive-class> <not-class> ]]
| "Q" QuotedCharacter*:s "\\E" => [[ s <concatenation> ]]
| "u" Character:a Character:b Character:c Character:d
=> [[ { a b c d } hex> ensure-number ]]