Parser Operators

Expression	Attribute	Description
`!a`	`Unused`	Not predicate. If the predicate `a` matches, fail. Otherwise, return a zero length match.
`&a`	`Unused`	And predicate. If the predicate `a` matches, return a zero length match. Otherwise, fail.
`-a`	`optional<A>`	Optional. Parse `a` zero or one time
`*a`	`vector<A>`	Kleene. Parse `a` zero or more times
`+a`	`vector<A>`	Plus. Parse `a` one or more times
`a \| b`	`variant<A, B>`	Alternative. Parse `a` or `b`
`a >> b`	`tuple<A, B>`	Sequence. Parse `a` followed by `b`
`a > b`	`tuple<A, B>`	Expect. Parse `a` followed by `b`. `b` is expected to match when `a` matches, otherwise, an `expectation_failure` is thrown.
`a - b`	`A`	Difference. Parse `a` but not `b`
`a \|\| b`	`tuple<` `optional<A>,` `optional<B> >`	Sequential Or. Parse `a` or `b` or `a` followed by `b`
`a % b`	`vector<A>`	List. Parse `a` delimited `b` one or more times
`a ^ b`	`tuple<` `optional<A>,` `optional<B> >`	Permutation. Parse `a` or `b` or `a` followed by `b` or `b` followed by `a`.

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