How to consume but not capture some chars, in PetitParser?

Question

I defined a rule:

def("invokation", char('@').word().plus().flatten());

For "@who", it will match and get @who as result.

How to ask it just return who without @?

Answer 1

Not sure if your question is about PetitParser for Java or Dart?

In any case, you need to connect char('@') and word().plus().flatten() to a sequence. Then you pick the second element of the list resulting list, ignoring the first character.

In Java this looks like this:

def("invokation", character('@')
    .seq(word().plus().flatten())
    .map(Functions.nthOfList(1));

And in Dart this is:

def("invokation", char('@')
    .seq(word().plus().flatten())
    .pick(1));

Btw, I just committed an improvement to PetitParser for Java so that you can use pick(int) in Java too.