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Commit c62a7041 authored by Georg Brandl's avatar Georg Brandl
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#6538: fix regex documentation again -- use fictional class names "regex" and... 

#6538: fix regex documentation again -- use fictional class names "regex" and "match" but do not document them as classes, remove 1.5 compat info and use new default argument syntax where possible.
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Doc/library/re.rst
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......@@ -33,8 +33,9 @@ newline. Usually patterns will be expressed in Python code using this raw
string notation.
It is important to note that most regular expression operations are available as
module-level functions and :class:`RegexObject` methods. The functions are
shortcuts that don't require you to compile a regex object first, but miss some
module-level functions and methods on
:ref:`compiled regular expressions <re-objects>`. The functions are shortcuts
that don't require you to compile a regex object first, but miss some
fine-tuning parameters.
.. seealso::
......@@ -546,21 +547,21 @@ form.
.. function:: search(pattern, string[, flags])
.. function:: search(pattern, string, flags=0)
Scan through *string* looking for a location where the regular expression
*pattern* produces a match, and return a corresponding :class:`MatchObject`
instance. Return ``None`` if no position in the string matches the pattern; note
that this is different from finding a zero-length match at some point in the
string.
*pattern* produces a match, and return a corresponding :ref:`match object
<match-objects>`. Return ``None`` if no position in the string matches the
pattern; note that this is different from finding a zero-length match at some
point in the string.
.. function:: match(pattern, string, flags=0)
If zero or more characters at the beginning of *string* match the regular
expression *pattern*, return a corresponding :class:`MatchObject` instance.
Return ``None`` if the string does not match the pattern; note that this is
different from a zero-length match.
expression *pattern*, return a corresponding :ref:`match object
<match-objects>`. Return ``None`` if the string does not match the pattern;
note that this is different from a zero-length match.
.. note::
......@@ -620,9 +621,9 @@ form.
.. function:: finditer(pattern, string, flags=0)
Return an :term:`iterator` yielding :class:`MatchObject` instances over all
non-overlapping matches for the RE *pattern* in *string*. The *string* is
scanned left-to-right, and matches are returned in the order found. Empty
Return an :term:`iterator` yielding :ref:`match objects <match-objects>` over
all non-overlapping matches for the RE *pattern* in *string*. The *string*
is scanned left-to-right, and matches are returned in the order found. Empty
matches are included in the result unless they touch the beginning of another
match.
......@@ -710,107 +711,107 @@ form.
Regular Expression Objects
--------------------------
.. class:: RegexObject
The :class:`RegexObject` class supports the following methods and attributes:
Compiled regular expression objects support the following methods and
attributes.
.. method:: RegexObject.search(string[, pos[, endpos]])
.. method:: regex.search(string[, pos[, endpos]])
Scan through *string* looking for a location where this regular expression
produces a match, and return a corresponding :class:`MatchObject` instance.
Return ``None`` if no position in the string matches the pattern; note that this
is different from finding a zero-length match at some point in the string.
Scan through *string* looking for a location where this regular expression
produces a match, and return a corresponding :ref:`match object
<match-objects>`. Return ``None`` if no position in the string matches the
pattern; note that this is different from finding a zero-length match at some
point in the string.
The optional second parameter *pos* gives an index in the string where the
search is to start; it defaults to ``0``. This is not completely equivalent to
slicing the string; the ``'^'`` pattern character matches at the real beginning
of the string and at positions just after a newline, but not necessarily at the
index where the search is to start.
The optional second parameter *pos* gives an index in the string where the
search is to start; it defaults to ``0``. This is not completely equivalent to
slicing the string; the ``'^'`` pattern character matches at the real beginning
of the string and at positions just after a newline, but not necessarily at the
index where the search is to start.
The optional parameter *endpos* limits how far the string will be searched; it
will be as if the string is *endpos* characters long, so only the characters
from *pos* to ``endpos - 1`` will be searched for a match. If *endpos* is less
than *pos*, no match will be found, otherwise, if *rx* is a compiled regular
expression object, ``rx.search(string, 0, 50)`` is equivalent to
``rx.search(string[:50], 0)``.
The optional parameter *endpos* limits how far the string will be searched; it
will be as if the string is *endpos* characters long, so only the characters
from *pos* to ``endpos - 1`` will be searched for a match. If *endpos* is less
than *pos*, no match will be found, otherwise, if *rx* is a compiled regular
expression object, ``rx.search(string, 0, 50)`` is equivalent to
``rx.search(string[:50], 0)``.
>>> pattern = re.compile("d")
>>> pattern.search("dog") # Match at index 0
<_sre.SRE_Match object at ...>
>>> pattern.search("dog", 1) # No match; search doesn't include the "d"
>>> pattern = re.compile("d")
>>> pattern.search("dog") # Match at index 0
<_sre.SRE_Match object at ...>
>>> pattern.search("dog", 1) # No match; search doesn't include the "d"
.. method:: RegexObject.match(string[, pos[, endpos]])
.. method:: regex.match(string[, pos[, endpos]])
If zero or more characters at the *beginning* of *string* match this regular
expression, return a corresponding :class:`MatchObject` instance. Return
``None`` if the string does not match the pattern; note that this is different
from a zero-length match.
If zero or more characters at the *beginning* of *string* match this regular
expression, return a corresponding :ref:`match object <match-objects>`.
Return ``None`` if the string does not match the pattern; note that this is
different from a zero-length match.
The optional *pos* and *endpos* parameters have the same meaning as for the
:meth:`~RegexObject.search` method.
The optional *pos* and *endpos* parameters have the same meaning as for the
:meth:`~regex.search` method.
.. note::
.. note::
If you want to locate a match anywhere in *string*, use
:meth:`~RegexObject.search` instead.
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 ...>
>>> 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 ...>
.. method:: RegexObject.split(string[, maxsplit=0])
.. method:: regex.split(string, maxsplit=0)
Identical to the :func:`split` function, using the compiled pattern.
Identical to the :func:`split` function, using the compiled pattern.
.. method:: RegexObject.findall(string[, pos[, endpos]])
.. method:: regex.findall(string[, pos[, endpos]])
Similar to the :func:`findall` function, using the compiled pattern, but
also accepts optional *pos* and *endpos* parameters that limit the search
region like for :meth:`match`.
Similar to the :func:`findall` function, using the compiled pattern, but
also accepts optional *pos* and *endpos* parameters that limit the search
region like for :meth:`match`.
.. method:: RegexObject.finditer(string[, pos[, endpos]])
.. method:: regex.finditer(string[, pos[, endpos]])
Similar to the :func:`finditer` function, using the compiled pattern, but
also accepts optional *pos* and *endpos* parameters that limit the search
region like for :meth:`match`.
Similar to the :func:`finditer` function, using the compiled pattern, but
also accepts optional *pos* and *endpos* parameters that limit the search
region like for :meth:`match`.
.. method:: RegexObject.sub(repl, string[, count=0])
.. method:: regex.sub(repl, string, count=0)
Identical to the :func:`sub` function, using the compiled pattern.
Identical to the :func:`sub` function, using the compiled pattern.
.. method:: RegexObject.subn(repl, string[, count=0])
.. method:: regex.subn(repl, string, count=0)
Identical to the :func:`subn` function, using the compiled pattern.
Identical to the :func:`subn` function, using the compiled pattern.
.. attribute:: RegexObject.flags
.. attribute:: regex.flags
The flags argument used when the RE object was compiled, or ``0`` if no flags
were provided.
The flags argument used when the RE object was compiled, or ``0`` if no flags
were provided.
.. attribute:: RegexObject.groups
.. attribute:: regex.groups
The number of capturing groups in the pattern.
The number of capturing groups in the pattern.
.. attribute:: RegexObject.groupindex
.. attribute:: regex.groupindex
A dictionary mapping any symbolic group names defined by ``(?P<id>)`` to group
numbers. The dictionary is empty if no symbolic groups were used in the
pattern.
A dictionary mapping any symbolic group names defined by ``(?P<id>)`` to group
numbers. The dictionary is empty if no symbolic groups were used in the
pattern.
.. attribute:: RegexObject.pattern
.. attribute:: regex.pattern
The pattern string from which the RE object was compiled.
The pattern string from which the RE object was compiled.
.. _match-objects:
......@@ -818,178 +819,176 @@ Regular Expression Objects
Match Objects
-------------
.. class:: MatchObject
Match Objects always have a boolean value of :const:`True`, so that you can test
whether e.g. :func:`match` resulted in a match with a simple if statement. They
support the following methods and attributes:
Match objects always have a boolean value of :const:`True`, so that you can test
whether e.g. :func:`match` resulted in a match with a simple if statement. They
support the following methods and attributes:
.. method:: MatchObject.expand(template)
.. method:: match.expand(template)
Return the string obtained by doing backslash substitution on the template
string *template*, as done by the :meth:`~RegexObject.sub` method. Escapes
such as ``\n`` are converted to the appropriate characters, and numeric
backreferences (``\1``, ``\2``) and named backreferences (``\g<1>``,
``\g<name>``) are replaced by the contents of the corresponding group.
Return the string obtained by doing backslash substitution on the template
string *template*, as done by the :meth:`~regex.sub` method.
Escapes such as ``\n`` are converted to the appropriate characters,
and numeric backreferences (``\1``, ``\2``) and named backreferences
(``\g<1>``, ``\g<name>``) are replaced by the contents of the
corresponding group.
.. method:: MatchObject.group([group1, ...])
.. method:: match.group([group1, ...])
Returns one or more subgroups of the match. If there is a single argument, the
result is a single string; if there are multiple arguments, the result is a
tuple with one item per argument. Without arguments, *group1* defaults to zero
(the whole match is returned). If a *groupN* argument is zero, the corresponding
return value is the entire matching string; if it is in the inclusive range
[1..99], it is the string matching the corresponding parenthesized group. If a
group number is negative or larger than the number of groups defined in the
pattern, an :exc:`IndexError` exception is raised. If a group is contained in a
part of the pattern that did not match, the corresponding result is ``None``.
If a group is contained in a part of the pattern that matched multiple times,
the last match is returned.
Returns one or more subgroups of the match. If there is a single argument, the
result is a single string; if there are multiple arguments, the result is a
tuple with one item per argument. Without arguments, *group1* defaults to zero
(the whole match is returned). If a *groupN* argument is zero, the corresponding
return value is the entire matching string; if it is in the inclusive range
[1..99], it is the string matching the corresponding parenthesized group. If a
group number is negative or larger than the number of groups defined in the
pattern, an :exc:`IndexError` exception is raised. If a group is contained in a
part of the pattern that did not match, the corresponding result is ``None``.
If a group is contained in a part of the pattern that matched multiple times,
the last match is returned.
>>> m = re.match(r"(\w+) (\w+)", "Isaac Newton, physicist")
>>> m.group(0) # The entire match
'Isaac Newton'
>>> m.group(1) # The first parenthesized subgroup.
'Isaac'
>>> m.group(2) # The second parenthesized subgroup.
'Newton'
>>> m.group(1, 2) # Multiple arguments give us a tuple.
('Isaac', 'Newton')
>>> m = re.match(r"(\w+) (\w+)", "Isaac Newton, physicist")
>>> m.group(0) # The entire match
'Isaac Newton'
>>> m.group(1) # The first parenthesized subgroup.
'Isaac'
>>> m.group(2) # The second parenthesized subgroup.
'Newton'
>>> m.group(1, 2) # Multiple arguments give us a tuple.
('Isaac', 'Newton')
If the regular expression uses the ``(?P<name>...)`` syntax, the *groupN*
arguments may also be strings identifying groups by their group name. If a
string argument is not used as a group name in the pattern, an :exc:`IndexError`
exception is raised.
If the regular expression uses the ``(?P<name>...)`` syntax, the *groupN*
arguments may also be strings identifying groups by their group name. If a
string argument is not used as a group name in the pattern, an :exc:`IndexError`
exception is raised.
A moderately complicated example:
A moderately complicated example:
>>> m = re.match(r"(?P<first_name>\w+) (?P<last_name>\w+)", "Malcolm Reynolds")
>>> m.group('first_name')
'Malcolm'
>>> m.group('last_name')
'Reynolds'
>>> m = re.match(r"(?P<first_name>\w+) (?P<last_name>\w+)", "Malcolm Reynolds")
>>> m.group('first_name')
'Malcolm'
>>> m.group('last_name')
'Reynolds'
Named groups can also be referred to by their index:
Named groups can also be referred to by their index:
>>> m.group(1)
'Malcolm'
>>> m.group(2)
'Reynolds'
>>> m.group(1)
'Malcolm'
>>> m.group(2)
'Reynolds'
If a group matches multiple times, only the last match is accessible:
If a group matches multiple times, only the last match is accessible:
>>> m = re.match(r"(..)+", "a1b2c3") # Matches 3 times.
>>> m.group(1) # Returns only the last match.
'c3'
>>> m = re.match(r"(..)+", "a1b2c3") # Matches 3 times.
>>> m.group(1) # Returns only the last match.
'c3'
.. method:: MatchObject.groups(default=None)
.. method:: match.groups(default=None)
Return a tuple containing all the subgroups of the match, from 1 up to however
many groups are in the pattern. The *default* argument is used for groups that
did not participate in the match; it defaults to ``None``.
Return a tuple containing all the subgroups of the match, from 1 up to however
many groups are in the pattern. The *default* argument is used for groups that
did not participate in the match; it defaults to ``None``.
For example:
For example:
>>> m = re.match(r"(\d+)\.(\d+)", "24.1632")
>>> m.groups()
('24', '1632')
>>> m = re.match(r"(\d+)\.(\d+)", "24.1632")
>>> m.groups()
('24', '1632')
If we make the decimal place and everything after it optional, not all groups
might participate in the match. These groups will default to ``None`` unless
the *default* argument is given:
If we make the decimal place and everything after it optional, not all groups
might participate in the match. These groups will default to ``None`` unless
the *default* argument is given:
>>> m = re.match(r"(\d+)\.?(\d+)?", "24")
>>> m.groups() # Second group defaults to None.
('24', None)
>>> m.groups('0') # Now, the second group defaults to '0'.
('24', '0')
>>> m = re.match(r"(\d+)\.?(\d+)?", "24")
>>> m.groups() # Second group defaults to None.
('24', None)
>>> m.groups('0') # Now, the second group defaults to '0'.
('24', '0')
.. method:: MatchObject.groupdict([default])
.. method:: match.groupdict(default=None)
Return a dictionary containing all the *named* subgroups of the match, keyed by
the subgroup name. The *default* argument is used for groups that did not
participate in the match; it defaults to ``None``. For example:
Return a dictionary containing all the *named* subgroups of the match, keyed by
the subgroup name. The *default* argument is used for groups that did not
participate in the match; it defaults to ``None``. For example:
>>> m = re.match(r"(?P<first_name>\w+) (?P<last_name>\w+)", "Malcolm Reynolds")
>>> m.groupdict()
{'first_name': 'Malcolm', 'last_name': 'Reynolds'}
>>> m = re.match(r"(?P<first_name>\w+) (?P<last_name>\w+)", "Malcolm Reynolds")
>>> m.groupdict()
{'first_name': 'Malcolm', 'last_name': 'Reynolds'}
.. method:: MatchObject.start([group])
MatchObject.end([group])
.. method:: match.start([group])
match.end([group])
Return the indices of the start and end of the substring matched by *group*;
*group* defaults to zero (meaning the whole matched substring). Return ``-1`` if
*group* exists but did not contribute to the match. For a match object *m*, and
a group *g* that did contribute to the match, the substring matched by group *g*
(equivalent to ``m.group(g)``) is ::
Return the indices of the start and end of the substring matched by *group*;
*group* defaults to zero (meaning the whole matched substring). Return ``-1`` if
*group* exists but did not contribute to the match. For a match object *m*, and
a group *g* that did contribute to the match, the substring matched by group *g*
(equivalent to ``m.group(g)``) is ::
m.string[m.start(g):m.end(g)]
m.string[m.start(g):m.end(g)]
Note that ``m.start(group)`` will equal ``m.end(group)`` if *group* matched a
null string. For example, after ``m = re.search('b(c?)', 'cba')``,
``m.start(0)`` is 1, ``m.end(0)`` is 2, ``m.start(1)`` and ``m.end(1)`` are both
2, and ``m.start(2)`` raises an :exc:`IndexError` exception.
Note that ``m.start(group)`` will equal ``m.end(group)`` if *group* matched a
null string. For example, after ``m = re.search('b(c?)', 'cba')``,
``m.start(0)`` is 1, ``m.end(0)`` is 2, ``m.start(1)`` and ``m.end(1)`` are both
2, and ``m.start(2)`` raises an :exc:`IndexError` exception.
An example that will remove *remove_this* from email addresses:
An example that will remove *remove_this* from email addresses:
>>> email = "tony@tiremove_thisger.net"
>>> m = re.search("remove_this", email)
>>> email[:m.start()] + email[m.end():]
'tony@tiger.net'
>>> email = "tony@tiremove_thisger.net"
>>> m = re.search("remove_this", email)
>>> email[:m.start()] + email[m.end():]
'tony@tiger.net'
.. method:: MatchObject.span([group])
.. method:: match.span([group])
For :class:`MatchObject` *m*, return the 2-tuple ``(m.start(group),
m.end(group))``. Note that if *group* did not contribute to the match, this is
``(-1, -1)``. *group* defaults to zero, the entire match.
For a match *m*, return the 2-tuple ``(m.start(group), m.end(group))``. Note
that if *group* did not contribute to the match, this is ``(-1, -1)``.
*group* defaults to zero, the entire match.
.. attribute:: MatchObject.pos
.. attribute:: match.pos
The value of *pos* which was passed to the :meth:`~RegexObject.search` or
:meth:`~RegexObject.match` method of the :class:`RegexObject`. This is the
index into the string at which the RE engine started looking for a match.
The value of *pos* which was passed to the :meth:`~regex.search` or
:meth:`~regex.match` method of a :ref:`match object <match-objects>`. This
is the index into the string at which the RE engine started looking for a
match.
.. attribute:: MatchObject.endpos
.. attribute:: match.endpos
The value of *endpos* which was passed to the :meth:`~RegexObject.search` or
:meth:`~RegexObject.match` method of the :class:`RegexObject`. This is the
index into the string beyond which the RE engine will not go.
The value of *endpos* which was passed to the :meth:`~regex.search` or
:meth:`~regex.match` method of a :ref:`match object <match-objects>`. This
is the index into the string beyond which the RE engine will not go.
.. attribute:: MatchObject.lastindex
.. attribute:: match.lastindex
The integer index of the last matched capturing group, or ``None`` if no group
was matched at all. For example, the expressions ``(a)b``, ``((a)(b))``, and
``((ab))`` will have ``lastindex == 1`` if applied to the string ``'ab'``, while
the expression ``(a)(b)`` will have ``lastindex == 2``, if applied to the same
string.
The integer index of the last matched capturing group, or ``None`` if no group
was matched at all. For example, the expressions ``(a)b``, ``((a)(b))``, and
``((ab))`` will have ``lastindex == 1`` if applied to the string ``'ab'``, while
the expression ``(a)(b)`` will have ``lastindex == 2``, if applied to the same
string.
.. attribute:: MatchObject.lastgroup
.. attribute:: match.lastgroup
The name of the last matched capturing group, or ``None`` if the group didn't
have a name, or if no group was matched at all.
The name of the last matched capturing group, or ``None`` if the group didn't
have a name, or if no group was matched at all.
.. attribute:: MatchObject.re
.. attribute:: match.re
The regular expression object whose :meth:`~RegexObject.match` or
:meth:`~RegexObject.search` method produced this :class:`MatchObject`
instance.
The regular expression object whose :meth:`~regex.match` or
:meth:`~regex.search` method produced this match instance.
.. attribute:: MatchObject.string
.. attribute:: match.string
The string passed to :meth:`~RegexObject.match` or
:meth:`~RegexObject.search`.
The string passed to :meth:`~regex.match` or :meth:`~regex.search`.
Examples
......@@ -1035,8 +1034,7 @@ To match this with a regular expression, one could use backreferences as such:
"<Match: '354aa', groups=('a',)>"
To find out what card the pair consists of, one could use the
:meth:`~MatchObject.group` method of :class:`MatchObject` in the following
manner:
:meth:`~match.group` method of the match object in the following manner:
.. doctest::
......@@ -1250,10 +1248,10 @@ Finding all Adverbs and their Positions
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If one wants more information about all matches of a pattern than the matched
text, :func:`finditer` is useful as it provides instances of
:class:`MatchObject` instead of strings. Continuing with the previous example,
if one was a writer who wanted to find all of the adverbs *and their positions*
in some text, he or she would use :func:`finditer` in the following manner:
text, :func:`finditer` is useful as it provides :ref:`match objects
<match-objects>` instead of strings. Continuing with the previous example, if
one was a writer who wanted to find all of the adverbs *and their positions* in
some text, he or she would use :func:`finditer` in the following manner:
>>> text = "He was carefully disguised but captured quickly by police."
>>> for m in re.finditer(r"\w+ly", text):
......
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