Commit eb335e66 authored by smurail's avatar smurail Committed by Romain Bignon

add an nth parameter to Regexp filter

parent 95322811
......@@ -22,6 +22,7 @@ from __future__ import absolute_import
import datetime
import re
from decimal import Decimal, InvalidOperation
from itertools import islice
from dateutil.parser import parse as parse_date
......@@ -408,30 +409,54 @@ class Field(_Filter):
return item.use_selector(getattr(item, 'obj_%s' % self.name))
# Based on nth from https://docs.python.org/2/library/itertools.html
def nth(iterable, n, default=None):
"Returns the nth item or a default value, n can be negative"
if n < 0:
iterable = reversed(list(iterable))
n = abs(n) - 1
return next(islice(iterable, n, None), default)
def ordinal(n):
"To have some readable debug information: 0 => 1st, 1 => 2nd..."
i = abs(n)
n = n - 1 if n < 0 else n + 1
return str(n) + ('th' if i > 2 else ['st', 'nd', 'rd'][i])
class Regexp(Filter):
r"""
Apply a regex.
>>> from lxml.html import etree
>>> f = Regexp(CleanText('//p'), r'Date: (\d+)/(\d+)/(\d+)', '\\3-\\2-\\1')
>>> f(etree.fromstring('<html><body><p>Date: <span>13/08/1988</span></p></body></html>'))
>>> doc = etree.fromstring('<html><body><p>Date: <span>13/08/1988</span></p></body></html>')
>>> Regexp(CleanText('//p'), r'Date: (\d+)/(\d+)/(\d+)', '\\3-\\2-\\1')(doc)
u'1988-08-13'
>>> (Regexp(CleanText('//body'), r'(\d+)', nth=1))(doc)
u'08'
>>> (Regexp(CleanText('//body'), r'(\d+)', nth=-1))(doc)
u'1988'
"""
def __init__(self, selector=None, pattern=None, template=None, flags=0, default=_NO_DEFAULT):
def __init__(self, selector=None, pattern=None, template=None, nth=0, flags=0, default=_NO_DEFAULT):
super(Regexp, self).__init__(selector, default=default)
assert pattern is not None
self.pattern = pattern
self.regex = re.compile(pattern, flags)
self.template = template
self.nth = nth
def filter(self, txt):
if isinstance(txt, (tuple, list)):
txt = u' '.join([t.strip() for t in txt.itertext()])
mobj = self.regex.search(txt)
mobj = self.regex.search(txt) if self.nth == 0 else \
nth(self.regex.finditer(txt), self.nth)
if not mobj:
return self.default_or_raise(RegexpError('Unable to match %s in %r' % (self.pattern, txt)))
msg = 'Unable to match %s %s in %r' % (ordinal(self.nth), self.pattern, txt)
return self.default_or_raise(RegexpError(msg))
if self.template is None:
return next(g for g in mobj.groups() if g is not None)
......
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