Match everything else doesn't work

[Linus Oleander]

I'm trying to get this code to work: https://gist.github.com/oleander/5d17f18e314b036ed2e6 matching questions on form "<number>. <question>?" surrounded by garbage.

I've manage to match an array of questions given no garbage using this top rule.

rule everything

  expression+

end

But the given example in my gist doesn't work. Why is that?

[Clifford Heath]

You can’t must prevent your repetition (+) from eating too much.
PEG parsers never backtrack on input that has been matched,
only on whole rules. One way to prevent that is the following:

rule question
( !following repeatable )+ following
end

rule following
‘?’
end

rule repeatable
.
end

(obviously you can redefine repeatable and following to match any
content)

Clifford Heath.

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[markus]

> But the given example in my gist doesn't work. Why is that?

I'm not somewhere where I can look at it closely, but at a glance it
looks like the problem may be that your text rule doesn't consume any
input. You might try something like:

rule text
( !expression . )+
end

To skip over characters until it reaches an expression instead of just
sitting where it doesn't match.

-- Markus