negateFlagValueParser function

ValueParser<bool> negateFlagValueParser(
  1. ValueParser<bool> parser
)

A ValueParser that wraps another ValueParser<bool> but flips the value. See ValueParserFlagExtensions.negateFlag for a slightly more elegant alternative.

var negatedParser = negateFlagValueParser(boolValueParser);
print(negatedParser('true'));   // false
print(negatedParser('false'));  // true

Implementation

ValueParser<bool> negateFlagValueParser(ValueParser<bool> parser) =>
    parser.then((value) => !value);