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merge with 3.3

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Georg Brandl 2013-10-06 12:08:58 +02:00
parent 7e41547c47 3c6780c6d8
commit 5993e29d36
1 changed files with 25 additions and 13 deletions
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Doc/library/re.rst
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@ -242,21 +242,32 @@ The special characters are:
``(?P<name>...)``
Similar to regular parentheses, but the substring matched by the group is
accessible within the rest of the regular expression via the symbolic group
name *name*. Group names must be valid Python identifiers, and each group
name must be defined only once within a regular expression. A symbolic group
is also a numbered group, just as if the group were not named. So the group
named ``id`` in the example below can also be referenced as the numbered group
``1``.
accessible via the symbolic group name *name*. Group names must be valid
Python identifiers, and each group name must be defined only once within a
regular expression. A symbolic group is also a numbered group, just as if
the group were not named.
For example, if the pattern is ``(?P<id>[a-zA-Z_]\w*)``, the group can be
referenced by its name in arguments to methods of match objects, such as
``m.group('id')`` or ``m.end('id')``, and also by name in the regular
expression itself (using ``(?P=id)``) and replacement text given to
``.sub()`` (using ``\g<id>``).
Named groups can be referenced in three contexts. If the pattern is
``(?P<quote>['"]).*?(?P=quote)`` (i.e. matching a string quoted with either
single or double quotes):
+---------------------------------------+----------------------------------+
| Context of reference to group "quote" | Ways to reference it |
+=======================================+==================================+
| in the same pattern itself | * ``(?P=quote)`` (as shown) |
| | * ``\1`` |
+---------------------------------------+----------------------------------+
| when processing match object ``m`` | * ``m.group('quote')`` |
| | * ``m.end('quote')`` (etc.) |
+---------------------------------------+----------------------------------+
| in a string passed to the ``repl`` | * ``\g<quote>`` |
| argument of ``re.sub()`` | * ``\g<1>`` |
| | * ``\1`` |
+---------------------------------------+----------------------------------+
``(?P=name)``
Matches whatever text was matched by the earlier group named *name*.
A backreference to a named group; it matches whatever text was matched by the
earlier group named *name*.
``(?#...)``
A comment; the contents of the parentheses are simply ignored.
@ -667,7 +678,8 @@ form.
when not adjacent to a previous match, so ``sub('x*', '-', 'abc')`` returns
``'-a-b-c-'``.
In addition to character escapes and backreferences as described above,
In string-type *repl* arguments, in addition to the character escapes and
backreferences described above,
``\g<name>`` will use the substring matched by the group named ``name``, as
defined by the ``(?P<name>...)`` syntax. ``\g<number>`` uses the corresponding
group number; ``\g<2>`` is therefore equivalent to ``\2``, but isn't ambiguous