comparisonOperator function

Implementation

Parser comparisonOperator() =>
    (string('==') |
            string('!=') |
            string('<=') |
            string('>=') |
            char('<') |
            char('>') |
            (string('contains') & word().not()).pick(0) |
            (string('in') & word().not()).pick(0))
        .labeled('comparisonOperator');