Paul McGuire <pt...@austin.rr.com> wrote:
> On Apr 3, 9:26 pm, Paul Rubin <http://phr...@nospam.invalid> wrote:
> > bwgoudey <bwgou...@gmail.com> writes:
> > > elif re.match("^DATASET:\s*(.+) ", line):
> > > m=re.match("^DATASET:\s*(.+) ", line)
> > > print m.group(1))
> >
> > Sometimes I like to make a special class that saves the result:
> >
> > class Reg(object): # illustrative code, not tested
> > def match(self, pattern, line):
> > self.result = re.match(pattern, line)
> > return self.result
> >
> I took this a little further, *and* lightly tested it too.
>
> Since this idiom makes repeated references to the input line, I added
> that to the constructor of the matching class.
>
> By using __call__, I made the created object callable, taking the RE
> expression as its lone argument and returning a boolean indicating
> match success or failure. The result of the re.match call is saved in
> self.matchresult.
>
> By using __getattr__, the created object proxies for the results of
> the re.match call.
>
> I think the resulting code looks pretty close to the original C or
> Perl idiom of cascading "elif (c=re_expr_match("..."))" blocks.
>
> (I thought about cacheing previously seen REs, or adding support for
> compiled REs instead of just strings - after all, this idiom usually
> occurs in a loop while iterating of some large body of text. It turns
> out that the re module already caches previously compiled REs, so I
> left my cacheing out in favor of that already being done in the std
> lib.)
>
>
> import re
>
> class REmatcher(object):
> def __init__(self,sourceline):
> self.line = sourceline
> def __call__(self, regexp):
> self.matchresult = re.match(regexp, self.line)
> self.success = self.matchresult is not None
> return self.success
> def __getattr__(self, attr):
> return getattr(self.matchresult, attr)
That is quite similar to the one I use...
"""
Matcher class encapsulating a call to re.search for ease of use in conditionals.
"""
import re
class Matcher(object):
"""
Matcher class
m = Matcher()
if m.search(r'add (\d+) (\d+)', line):
do_add(m[0], m[1])
elif m.search(r'mult (\d+) (\d+)', line):
do_mult(m[0], m[1])
elif m.search(r'help (\w+)', line):
show_help(m[0])
"""
def search(self, r, s):
"""
Do a regular expression search and return if it matched.
"""
self.value = re.search(r, s)
return self.value
def __getitem__(self, n):
"""
Return n'th matched () item.
Note so the first matched item will be matcher[0]
"""
return self.value.group(n+1)
def groups(self):
"""
Return all the matched () items.
"""
return self.value.groups()
--
Nick Craig-Wood <n...@craig-wood.com> -- http://www.craig-wood.com/nick
--
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