[cl-ppcre-devel] Strange parsing

[Ken Harris]

Hi, all,

When playing around with cl-ppcre 2.0.1, I've discovered this:

 (cl-ppcre::parse-string "?") -> :QUESTION-MARK

I found this odd, since :QUESTION-MARK isn't part of the parse-tree
grammar in the docs.  Two or more ("??", "???", etc.) also leave a
:QUESTION-MARK in the parse-tree.  I took a quick look at the source
code, and it looks like :QUESTION-MARK is used by the lexer (with
other keywords like :CLOSE-PAREN), but that it seems to expect them to
be replaced by the time you end up with a parse-tree.

In comparison, if you try to use ")", like (cl-ppcre::parse-string
")"), it signals a condition in parse-string.  I can't find any way to
get :CLOSE-PAREN in the output.  It's a little weird that it can parse
"??" but then signals if you try to use it.

If I try to cl-ppcre:scan anything with one of these, I get a
ppcre-syntax-error, "Unknown token QUESTION-MARK in parse tree".  I
don't know if this is a bug or not, and I don't think I'm going to run
into a situation where this matters, but there you go.  :-)

cheers,


- Ken