sysconfig.py contains a pattern that breaks SRE:
import re, pre pre.compile(r"\${([A-Za-z][A-Za-z0-9_]*)}") <pre.RegexObject instance at 0x827a394> re.compile(r"\${([A-Za-z][A-Za-z0-9_]*)}") Traceback (most recent call last): File "<stdin>", line 1, in ? File "/usr/lib/python2.0/sre.py", line 54, in compile return _compile(pattern, flags) ... File "/usr/lib/python2.0/sre_parse.py", line 538, in parse p = _parse(source, state) File "/usr/lib/python2.0/sre_parse.py", line 394, in _parse raise error, "bogus range"
Escaping the { and } fix this. This is a problem with the {xxx,yyy} notation for ranges; PCRE looks ahead, and treats it as a literal unless it's followed by digits of the right form. From pypcre.c: /* This function is called when a '{' is encountered in a place where it might start a quantifier. It looks ahead to see if it really is a quantifier or not. It is only a quantifier if it is one of the forms {ddd} {ddd,} or {ddd,ddd} where the ddds are digits. */ I suppose the goal of Perl compatibility means this magical behaviour needs to be preserved? --amk
andrew wrote:
sysconfig.py contains a pattern that breaks SRE:
import re, pre pre.compile(r"\${([A-Za-z][A-Za-z0-9_]*)}") <pre.RegexObject instance at 0x827a394> re.compile(r"\${([A-Za-z][A-Za-z0-9_]*)}") Traceback (most recent call last): File "<stdin>", line 1, in ? File "/usr/lib/python2.0/sre.py", line 54, in compile return _compile(pattern, flags) ... File "/usr/lib/python2.0/sre_parse.py", line 538, in parse p = _parse(source, state) File "/usr/lib/python2.0/sre_parse.py", line 394, in _parse raise error, "bogus range"
Escaping the { and } fix this. This is a problem with the {xxx,yyy} notation for ranges; PCRE looks ahead, and treats it as a literal unless it's followed by digits of the right form. From pypcre.c:
/* This function is called when a '{' is encountered in a place where it might start a quantifier. It looks ahead to see if it really is a quantifier or not. It is only a quantifier if it is one of the forms {ddd} {ddd,} or {ddd,ddd} where the ddds are digits. */
I suppose the goal of Perl compatibility means this magical behaviour needs to be preserved?
I'm not so sure about this one; the $ behaviour is documented in Perl, but this isn't (as far as I can tell, at least). and since it's detected by the parser, it's probably better to change the sysconfig module... (fixing this in the sre_parser isn't exactly trivial, either...) </F>
participants (2)
-
A.M. Kuchling -
Fredrik Lundh