Member predicate RegExp::namedCharacterPropertyIsInverted

Holds if the named character property is inverted. Examples for which it holds:

• \P{Digit} upper-case P means inverted
• \p{^Word} caret also means inverted (not supported in Swift Regex but it may be in other regex parsers or in future versions of Swift).
• [[:^digit:]]

Examples for which it doesn’t hold:

• \p{Word}
• \P{^Space} - upper-case P and caret cancel each other out
• [[:alnum:]]