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Issue #10875: Update Regular Expression HOWTO; patch by 'SilentGhost'.

This commit is contained in:
Terry Reedy 2011-01-10 22:15:19 +00:00
parent cbdfc97d47
commit f7dd7998de
2 changed files with 13 additions and 12 deletions
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23
Doc/howto/regex.rst
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@ -5,7 +5,6 @@
**************************** ****************************
:Author: A.M. Kuchling <amk@amk.ca> :Author: A.M. Kuchling <amk@amk.ca>
:Release: 0.05
.. TODO: .. TODO:
Document lookbehind assertions Document lookbehind assertions
@ -264,7 +263,7 @@ performing string substitutions. ::
>>> import re >>> import re
>>> p = re.compile('ab*') >>> p = re.compile('ab*')
>>> print p >>> print p
<_sre.SRE_Pattern object at 80b4150> <_sre.SRE_Pattern object at 0x...>
:func:`re.compile` also accepts an optional *flags* argument, used to enable :func:`re.compile` also accepts an optional *flags* argument, used to enable
various special features and syntax variations. We'll go over the available various special features and syntax variations. We'll go over the available
@ -377,7 +376,7 @@ Python interpreter, import the :mod:`re` module, and compile a RE::
>>> import re >>> import re
>>> p = re.compile('[a-z]+') >>> p = re.compile('[a-z]+')
>>> p >>> p
<_sre.SRE_Pattern object at 80c3c28> <_sre.SRE_Pattern object at 0x...>
Now, you can try matching various strings against the RE ``[a-z]+``. An empty Now, you can try matching various strings against the RE ``[a-z]+``. An empty
string shouldn't match at all, since ``+`` means 'one or more repetitions'. string shouldn't match at all, since ``+`` means 'one or more repetitions'.
@ -395,7 +394,7 @@ result in a variable for later use. ::
>>> m = p.match('tempo') >>> m = p.match('tempo')
>>> print m >>> print m
<_sre.SRE_Match object at 80c4f68> <_sre.SRE_Match object at 0x...>
Now you can query the :class:`MatchObject` for information about the matching Now you can query the :class:`MatchObject` for information about the matching
string. :class:`MatchObject` instances also have several methods and string. :class:`MatchObject` instances also have several methods and
@ -434,7 +433,7 @@ case. ::
>>> print p.match('::: message') >>> print p.match('::: message')
None None
>>> m = p.search('::: message') ; print m >>> m = p.search('::: message') ; print m
<re.MatchObject instance at 80c9650> <_sre.SRE_Match object at 0x...>
>>> m.group() >>> m.group()
'message' 'message'
>>> m.span() >>> m.span()
@ -485,7 +484,7 @@ the RE string added as the first argument, and still return either ``None`` or a
>>> print re.match(r'From\s+', 'Fromage amk') >>> print re.match(r'From\s+', 'Fromage amk')
None None
>>> re.match(r'From\s+', 'From amk Thu May 14 19:12:10 1998') >>> re.match(r'From\s+', 'From amk Thu May 14 19:12:10 1998')
<re.MatchObject instance at 80c5978> <_sre.SRE_Match object at 0x...>
Under the hood, these functions simply create a pattern object for you Under the hood, these functions simply create a pattern object for you
and call the appropriate method on it. They also store the compiled object in a and call the appropriate method on it. They also store the compiled object in a
@ -686,7 +685,7 @@ given location, they can obviously be matched an infinite number of times.
line, the RE to use is ``^From``. :: line, the RE to use is ``^From``. ::
>>> print re.search('^From', 'From Here to Eternity') >>> print re.search('^From', 'From Here to Eternity')
<re.MatchObject instance at 80c1520> <_sre.SRE_Match object at 0x...>
>>> print re.search('^From', 'Reciting From Memory') >>> print re.search('^From', 'Reciting From Memory')
None None
@ -698,11 +697,11 @@ given location, they can obviously be matched an infinite number of times.
or any location followed by a newline character. :: or any location followed by a newline character. ::
>>> print re.search('}$', '{block}') >>> print re.search('}$', '{block}')
<re.MatchObject instance at 80adfa8> <_sre.SRE_Match object at 0x...>
>>> print re.search('}$', '{block} ') >>> print re.search('}$', '{block} ')
None None
>>> print re.search('}$', '{block}\n') >>> print re.search('}$', '{block}\n')
<re.MatchObject instance at 80adfa8> <_sre.SRE_Match object at 0x...>
To match a literal ``'$'``, use ``\$`` or enclose it inside a character class, To match a literal ``'$'``, use ``\$`` or enclose it inside a character class,
as in ``[$]``. as in ``[$]``.
@ -727,7 +726,7 @@ given location, they can obviously be matched an infinite number of times.
>>> p = re.compile(r'\bclass\b') >>> p = re.compile(r'\bclass\b')
>>> print p.search('no class at all') >>> print p.search('no class at all')
<re.MatchObject instance at 80c8f28> <_sre.SRE_Match object at 0x...>
>>> print p.search('the declassified algorithm') >>> print p.search('the declassified algorithm')
None None
>>> print p.search('one subclass is') >>> print p.search('one subclass is')
@ -745,7 +744,7 @@ given location, they can obviously be matched an infinite number of times.
>>> print p.search('no class at all') >>> print p.search('no class at all')
None None
>>> print p.search('\b' + 'class' + '\b') >>> print p.search('\b' + 'class' + '\b')
<re.MatchObject instance at 80c3ee0> <_sre.SRE_Match object at 0x...>
Second, inside a character class, where there's no use for this assertion, Second, inside a character class, where there's no use for this assertion,
``\b`` represents the backspace character, for compatibility with Python's ``\b`` represents the backspace character, for compatibility with Python's
@ -1315,7 +1314,7 @@ a regular expression that handles all of the possible cases, the patterns will
be *very* complicated. Use an HTML or XML parser module for such tasks.) be *very* complicated. Use an HTML or XML parser module for such tasks.)
Not Using re.VERBOSE Using re.VERBOSE
-------------------- --------------------
By now you've probably noticed that regular expressions are a very compact By now you've probably noticed that regular expressions are a very compact

2
Misc/NEWS
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@ -29,6 +29,8 @@ Core and Builtins
Library Library
------- -------
- Issue #10875: Update Regular Expression HOWTO; patch by 'SilentGhost'.
- Issue #10827: Changed the rules for 2-digit years. The time.asctime - Issue #10827: Changed the rules for 2-digit years. The time.asctime
function will now format any year when ``time.accept2dyear`` is function will now format any year when ``time.accept2dyear`` is
false and will accept years >= 1000 otherwise. The year range false and will accept years >= 1000 otherwise. The year range