/foo$/ works for the example script. "foo" /\Z/ didn't match anything (though /foo\Z/ did). All fall down if I test with this grammar:

line: FOO BAR
FOO: /foo\Z/
BAR: /bar\Z/
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(and use $p->line instead of $p->foo). I probably should have been more specific, but I'm looking for a more generalised solution to this, or at least some understanding of where my expectations are wrong.