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