parser top-level property

Parser<Expression> parser

Implementation

final parser = () {
  final builder = ExpressionBuilder<Expression>();
  builder
    ..primitive(
      (digit().plus() &
              (char('.') & digit().plus()).optional() &
              (pattern('eE') & pattern('+-').optional() & digit().plus())
                  .optional())
          .flatten(message: 'number expected')
          .trim()
          .map(_createValue),
    )
    ..primitive(
      seq2(
        seq2(letter(), word().star()).flatten(message: 'name expected').trim(),
        seq3(
          char('(').trim(),
          builder.loopback
              .starSeparated(char(',').trim())
              .map((list) => list.elements),
          char(')').trim(),
        ).map3((_, list, _) => list).optionalWith(const <Expression>[]),
      ).map2((name, args) => _createBinding(name, args)),
    );
  builder.group().wrapper(
    char('(').trim(),
    char(')').trim(),
    (left, value, right) => value,
  );
  builder.group()
    ..prefix(char('+').trim(), (op, a) => a)
    ..prefix(char('-').trim(), (op, a) => Application('-', [a], (x) => -x));
  builder.group().right(
    char('^').trim(),
    (a, op, b) => Application('^', [a, b], math.pow),
  );
  builder.group()
    ..left(
      char('*').trim(),
      (a, op, b) => Application('*', [a, b], (x, y) => x * y),
    )
    ..left(
      char('/').trim(),
      (a, op, b) => Application('/', [a, b], (x, y) => x / y),
    );
  builder.group()
    ..left(
      char('+').trim(),
      (a, op, b) => Application('+', [a, b], (x, y) => x + y),
    )
    ..left(
      char('-').trim(),
      (a, op, b) => Application('-', [a, b], (x, y) => x - y),
    );
  return resolve(builder.build()).end();
}();