Parse error

[toots]

This pcre generates a parse error:

Re.Pcre.regexp "#{([^}]*?)}"
Exception raised: Re__Perl.Parse_error
Raised at Re__Perl.parse.atom in file "lib/perl.ml", line 168, characters 40-57
Called from Re__Perl.parse.piece in file "lib/perl.ml", line 83, characters 12-19
Called from Re__Perl.parse.branch' in file "lib/perl.ml", line 81, characters 18-26
Called from Re__Perl.parse.regexp in file "lib/perl.ml" (inlined), line 75, characters 30-41
Called from Re__Perl.parse in file "lib/perl.ml", line 253, characters 12-21
Called from Re__Perl.re in file "lib/perl.ml", line 263, characters 4-142
Called from Re__Pcre.regexp in file "lib/pcre.ml" (inlined), line 23, characters 35-50

It seems perfectly valid for ocaml-pcre, node and perl's pcre.

[bcc32]

I don't have a particular opinion on how ocaml-re should handle this, but I got nerd-sniped so here's what I found:

FWIW, in sufficiently new perl (v5.22 and newer), this regexp produces a warning:

Unescaped left brace in regex is passed through in regex; marked by <-- HERE in m/#{ <-- HERE ([^}]*?)}/ at temp.pl line 4.

The curly braces normally indicate a repetition count, but no valid integer is found between them. Perl just treats them as literal characters in this case, but this usage is apparently deprecated (from man perlre):

(If a non-escaped curly bracket occurs in a context other than one of the quantifiers listed above, where it does not form part of a backslashed sequence like "\x{...}", it is either a fatal syntax error, or treated as a regular character, generally with a deprecation warning raised. To escape it, you can precede it with a backslash ("{") or enclose it within square brackets ("[{]"). This change will allow for future syntax extensions (like making the lower bound of a quantifier optional), and better error checking of quantifiers).

[toots]

Thanks that's very informative. I think it'd be nice is the library can be permissive with its entries to allow for seamless migration from other pcre stack, while perhaps displaying a warning for instance.

I have another similar one that I'm about to submit.