Merge heads.

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Ezio Melotti 2011-10-20 19:45:39 +03:00
commit 9927e0ce35
1 changed files with 28 additions and 22 deletions

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@ -161,30 +161,36 @@ The special characters are:
raw strings for all but the simplest expressions.
``[]``
Used to indicate a set of characters. Characters can be listed individually, or
a range of characters can be indicated by giving two characters and separating
them by a ``'-'``. Special characters are not active inside sets. For example,
``[akm$]`` will match any of the characters ``'a'``, ``'k'``,
``'m'``, or ``'$'``; ``[a-z]`` will match any lowercase letter, and
``[a-zA-Z0-9]`` matches any letter or digit. Character classes such
as ``\w`` or ``\S`` (defined below) are also acceptable inside a
range, although the characters they match depends on whether
:const:`ASCII` or :const:`LOCALE` mode is in force. If you want to
include a ``']'`` or a ``'-'`` inside a set, precede it with a
backslash, or place it as the first character. The pattern ``[]]``
will match ``']'``, for example.
Used to indicate a set of characters. In a set:
You can match the characters not within a range by :dfn:`complementing` the set.
This is indicated by including a ``'^'`` as the first character of the set;
``'^'`` elsewhere will simply match the ``'^'`` character. For example,
``[^5]`` will match any character except ``'5'``, and ``[^^]`` will match any
character except ``'^'``.
* Characters can be listed individually, e.g. ``[amk]`` will match ``'a'``,
``'m'``, or ``'k'``.
Note that inside ``[]`` the special forms and special characters lose
their meanings and only the syntaxes described here are valid. For
example, ``+``, ``*``, ``(``, ``)``, and so on are treated as
literals inside ``[]``, and backreferences cannot be used inside
``[]``.
* Ranges of characters can be indicated by giving two characters and separating
them by a ``'-'``, for example ``[a-z]`` will match any lowercase ASCII letter,
``[0-5][0-9]`` will match all the two-digits numbers from ``00`` to ``59``, and
``[0-9A-Fa-f]`` will match any hexadecimal digit. If ``-`` is escaped (e.g.
``[a\-z]``) or if it's placed as the first or last character (e.g. ``[a-]``),
it will match a literal ``'-'``.
* Special characters lose their special meaning inside sets. For example,
``[(+*)]`` will match any of the literal characters ``'('``, ``'+'``,
``'*'``, or ``')'``.
* Character classes such as ``\w`` or ``\S`` (defined below) are also accepted
inside a set, although the characters they match depends on whether
:const:`ASCII` or :const:`LOCALE` mode is in force.
* Characters that are not within a range can be matched by :dfn:`complementing`
the set. If the first character of the set is ``'^'``, all the characters
that are *not* in the set will be matched. For example, ``[^5]`` will match
any character except ``'5'``, and ``[^^]`` will match any character except
``'^'``. ``^`` has no special meaning if it's not the first character in
the set.
* To match a literal ``']'`` inside a set, precede it with a backslash, or
place it at the beginning of the set. For example, both ``[()[\]{}]`` and
``[]()[{}]`` will both match a parenthesis.
``'|'``
``A|B``, where A and B can be arbitrary REs, creates a regular expression that