#14155: merge with 3.2.

This commit is contained in:
Ezio Melotti 2012-02-29 13:40:11 +02:00
commit 6ea00ef25a
1 changed files with 31 additions and 55 deletions

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@ -423,31 +423,6 @@ a group reference. As for string literals, octal escapes are always at most
three digits in length.
.. _matching-searching:
Matching vs. Searching
----------------------
.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
Python offers two different primitive operations based on regular expressions:
**match** checks for a match only at the beginning of the string, while
**search** checks for a match anywhere in the string (this is what Perl does
by default).
Note that match may differ from search even when using a regular expression
beginning with ``'^'``: ``'^'`` matches only at the start of the string, or in
:const:`MULTILINE` mode also immediately following a newline. The "match"
operation succeeds only if the pattern matches at the start of the string
regardless of mode, or at the starting position given by the optional *pos*
argument regardless of whether a newline precedes it.
>>> re.match("c", "abcdef") # No match
>>> re.search("c", "abcdef") # Match
<_sre.SRE_Match object at ...>
.. _contents-of-module-re:
Module Contents
@ -581,10 +556,11 @@ form.
<match-objects>`. Return ``None`` if the string does not match the pattern;
note that this is different from a zero-length match.
.. note::
Note that even in :const:`MULTILINE` mode, :func:`re.match` will only match
at the beginning of the string and not at the beginning of each line.
If you want to locate a match anywhere in *string*, use :func:`search`
instead.
If you want to locate a match anywhere in *string*, use :func:`search`
instead (see also :ref:`search-vs-match`).
.. function:: split(pattern, string, maxsplit=0, flags=0)
@ -771,16 +747,14 @@ attributes:
The optional *pos* and *endpos* parameters have the same meaning as for the
:meth:`~regex.search` method.
.. note::
If you want to locate a match anywhere in *string*, use
:meth:`~regex.search` instead.
>>> pattern = re.compile("o")
>>> pattern.match("dog") # No match as "o" is not at the start of "dog".
>>> pattern.match("dog", 1) # Match as "o" is the 2nd character of "dog".
<_sre.SRE_Match object at ...>
If you want to locate a match anywhere in *string*, use
:meth:`~regex.search` instead (see also :ref:`search-vs-match`).
.. method:: regex.split(string, maxsplit=0)
@ -1142,37 +1116,39 @@ the above regular expression can avoid recursion by being recast as ``Begin
[a-zA-Z0-9_ ]*?end``. As a further benefit, such regular expressions will run
faster than their recursive equivalents.
.. _search-vs-match:
search() vs. match()
^^^^^^^^^^^^^^^^^^^^
In a nutshell, :func:`match` only attempts to match a pattern at the beginning
of a string where :func:`search` will match a pattern anywhere in a string.
For example:
.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
>>> re.match("o", "dog") # No match as "o" is not the first letter of "dog".
>>> re.search("o", "dog") # Match as search() looks everywhere in the string.
Python offers two different primitive operations based on regular expressions:
:func:`re.match` checks for a match only at the beginning of the string, while
:func:`re.search` checks for a match anywhere in the string (this is what Perl
does by default).
For example::
>>> re.match("c", "abcdef") # No match
>>> re.search("c", "abcdef") # Match
<_sre.SRE_Match object at ...>
.. note::
Regular expressions beginning with ``'^'`` can be used with :func:`search` to
restrict the match at the beginning of the string::
The following applies only to regular expression objects like those created
with ``re.compile("pattern")``, not the primitives ``re.match(pattern,
string)`` or ``re.search(pattern, string)``.
:func:`match` has an optional second parameter that gives an index in the string
where the search is to start::
>>> pattern = re.compile("o")
>>> pattern.match("dog") # No match as "o" is not at the start of "dog."
# Equivalent to the above expression as 0 is the default starting index:
>>> pattern.match("dog", 0)
# Match as "o" is the 2nd character of "dog" (index 0 is the first):
>>> pattern.match("dog", 1)
>>> re.match("c", "abcdef") # No match
>>> re.search("^c", "abcdef") # No match
>>> re.search("^a", "abcdef") # Match
<_sre.SRE_Match object at ...>
Note however that in :const:`MULTILINE` mode :func:`match` only matches at the
beginning of the string, whereas using :func:`search` with a regular expression
beginning with ``'^'`` will match at the beginning of each line.
>>> re.match('X', 'A\nB\nX', re.MULTILINE) # No match
>>> re.search('^X', 'A\nB\nX', re.MULTILINE) # Match
<_sre.SRE_Match object at ...>
>>> pattern.match("dog", 2) # No match as "o" is not the 3rd character of "dog."
Making a Phonebook