From: Georg Brandl <georg@python.org>
Date: Thu, 6 Mar 2008 07:19:15 +0000 (+0000)
Subject: Expand on re.split behavior with captured expressions.
X-Git-Tag: v2.6a2~371
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=70992c3c83e2324677ad4fee73f372682f036c18;p=python

Expand on re.split behavior with captured expressions.
---

diff --git a/Doc/library/re.rst b/Doc/library/re.rst
index 9f13d06b92..2ab12546e9 100644
--- a/Doc/library/re.rst
+++ b/Doc/library/re.rst
@@ -543,14 +543,26 @@ form.
       >>> re.split('\W+', 'Words, words, words.', 1)
       ['Words', 'words, words.']
 
+   If there are capturing groups in the separator and it matches at the start of
+   the string, the result will start with an empty string.  The same holds for
+   the end of the string::
+
+      >>> re.split('(\W+)', '...words, words...')
+      ['', '...', 'words', ', ', 'words', '...', '']
+
+   That way, separator components are always found at the same relative
+   indices within the result list (e.g., if there's one capturing group
+   in the separator, the 0th, the 2nd and so forth).
+
    Note that *split* will never split a string on an empty pattern match.
-   For example ::
+   For example::
 
       >>> re.split('x*', 'foo')
       ['foo']
       >>> re.split("(?m)^$", "foo\n\nbar\n")
       ['foo\n\nbar\n']
 
+
 .. function:: findall(pattern, string[, flags])
 
    Return all non-overlapping matches of *pattern* in *string*, as a list of