regex-syntax.sgml

this is a glib for c language

    <entry>any "word" character</entry>
  </row>
  <row>
    <entry>\W</entry>
    <entry>any "non-word" character</entry>
  </row>
</tbody>
</tgroup>
</table>

<para>
Each pair of escape sequences partitions the complete set of characters
into two disjoint sets. Any given character matches one, and only one,
of each pair.
</para>

<para>
These character type sequences can appear both inside and outside character
classes. They each match one character of the appropriate type.
If the current matching point is at the end of the passed string, all
of them fail, since there is no character to match.
</para>

<para>
For compatibility with Perl, \s does not match the VT character (code
11). This makes it different from the the POSIX "space" class. The \s
characters are HT (9), LF (10), FF (12), CR (13), and space (32).
</para>

<para>
A "word" character is an underscore or any character less than 256 that
is a letter or digit.</para>

<para>
Characters with values greater than 128 never match \d,
\s, or \w, and always match \D, \S, and \W.
</para>
</refsect2>

<refsect2>
<title>Newline sequences</title>
<para>Outside a character class, the escape sequence \R matches any Unicode
newline sequence.
This particular group matches either the two-character sequence CR followed by
LF, or one of the single characters LF (linefeed, U+000A), VT (vertical tab,
U+000B), FF (formfeed, U+000C), CR (carriage return, U+000D), NEL (next
line, U+0085), LS (line separator, U+2028), or PS (paragraph separator, U+2029).
The two-character sequence is treated as a single unit that
cannot be split. Inside a character class, \R matches the letter "R".</para>
</refsect2>

<refsect2>
<title>Unicode character properties</title>
<para>
To support generic character types there are three additional escape
sequences, they are:
</para>

<table frame="all" colsep="1" rowsep="1">
<title>Generic character types</title>
<tgroup cols="2">
<colspec colnum="1" align="center"/>
<thead>
  <row>
    <entry>Escape</entry>
    <entry>Meaning</entry>
  </row>
</thead>
<tbody>
  <row>
    <entry>\p{xx}</entry>
    <entry>a character with the xx property</entry>
  </row>
  <row>
    <entry>\P{xx}</entry>
    <entry>a character without the xx property</entry>
  </row>
  <row>
    <entry>\X</entry>
    <entry>an extended Unicode sequence</entry>
  </row>
</tbody>
</tgroup>
</table>

<para>
The property names represented by xx above are limited to the Unicode
script names, the general category properties, and "Any", which matches
any character (including newline). Other properties such as "InMusicalSymbols"
are not currently supported. Note that \P{Any} does not match any characters,
so always causes a match failure.
</para>

<para>
Sets of Unicode characters are defined as belonging to certain scripts. A
character from one of these sets can be matched using a script name. For
example, \p{Greek} or \P{Han}.
</para>

<para>
Those that are not part of an identified script are lumped together as
"Common". The current list of scripts is:
</para>

<itemizedlist>
<listitem><para>Arabic</para></listitem>
<listitem><para>Armenian</para></listitem>
<listitem><para>Balinese</para></listitem>
<listitem><para>Bengali</para></listitem>
<listitem><para>Bopomofo</para></listitem>
<listitem><para>Braille</para></listitem>
<listitem><para>Buginese</para></listitem>
<listitem><para>Buhid</para></listitem>
<listitem><para>Canadian_Aboriginal</para></listitem>
<listitem><para>Cherokee</para></listitem>
<listitem><para>Common</para></listitem>
<listitem><para>Coptic</para></listitem>
<listitem><para>Cuneiform</para></listitem>
<listitem><para>Cypriot</para></listitem>
<listitem><para>Cyrillic</para></listitem>
<listitem><para>Deseret</para></listitem>
<listitem><para>Devanagari</para></listitem>
<listitem><para>Ethiopic</para></listitem>
<listitem><para>Georgian</para></listitem>
<listitem><para>Glagolitic</para></listitem>
<listitem><para>Gothic</para></listitem>
<listitem><para>Greek</para></listitem>
<listitem><para>Gujarati</para></listitem>
<listitem><para>Gurmukhi</para></listitem>
<listitem><para>Han</para></listitem>
<listitem><para>Hangul</para></listitem>
<listitem><para>Hanunoo</para></listitem>
<listitem><para>Hebrew</para></listitem>
<listitem><para>Hiragana</para></listitem>
<listitem><para>Inherited</para></listitem>
<listitem><para>Kannada</para></listitem>
<listitem><para>Katakana</para></listitem>
<listitem><para>Kharoshthi</para></listitem>
<listitem><para>Khmer</para></listitem>
<listitem><para>Lao</para></listitem>
<listitem><para>Latin</para></listitem>
<listitem><para>Limbu</para></listitem>
<listitem><para>Linear_B</para></listitem>
<listitem><para>Malayalam</para></listitem>
<listitem><para>Mongolian</para></listitem>
<listitem><para>Myanmar</para></listitem>
<listitem><para>New_Tai_Lue</para></listitem>
<listitem><para>Nko</para></listitem>
<listitem><para>Ogham</para></listitem>
<listitem><para>Old_Italic</para></listitem>
<listitem><para>Old_Persian</para></listitem>
<listitem><para>Oriya</para></listitem>
<listitem><para>Osmanya</para></listitem>
<listitem><para>Phags_Pa</para></listitem>
<listitem><para>Phoenician</para></listitem>
<listitem><para>Runic</para></listitem>
<listitem><para>Shavian</para></listitem>
<listitem><para>Sinhala</para></listitem>
<listitem><para>Syloti_Nagri</para></listitem>
<listitem><para>Syriac</para></listitem>
<listitem><para>Tagalog</para></listitem>
<listitem><para>Tagbanwa</para></listitem>
<listitem><para>Tai_Le</para></listitem>
<listitem><para>Tamil</para></listitem>
<listitem><para>Telugu</para></listitem>
<listitem><para>Thaana</para></listitem>
<listitem><para>Thai</para></listitem>
<listitem><para>Tibetan</para></listitem>
<listitem><para>Tifinagh</para></listitem>
<listitem><para>Ugaritic</para></listitem>
<listitem><para>Yi</para></listitem>
</itemizedlist>

<para>
Each character has exactly one general category property, specified by a
two-letter abbreviation. For compatibility with Perl, negation can be specified
by including a circumflex between the opening brace and the property name. For
example, \p{^Lu} is the same as \P{Lu}.
</para>

<para>
If only one letter is specified with \p or \P, it includes all the general
category properties that start with that letter. In this case, in the absence
of negation, the curly brackets in the escape sequence are optional; these two
examples have the same effect:
</para>

<programlisting>
\p{L}
\pL
</programlisting>

<para>
The following general category property codes are supported:
</para>

<table frame="all" colsep="1" rowsep="1">
<title>Property codes</title>
<tgroup cols="2">
<colspec colnum="1" align="center"/>
<thead>
  <row>
    <entry>Code</entry>
    <entry>Meaning</entry>
  </row>
</thead>
<tbody>
  <row>
    <entry>C</entry>
    <entry>Other</entry>
  </row>
  <row>
    <entry>Cc</entry>
    <entry>Control</entry>
  </row>
  <row>
    <entry>Cf</entry>
    <entry>Format</entry>
  </row>
  <row>
    <entry>Cn</entry>
    <entry>Unassigned</entry>
  </row>
  <row>
    <entry>Co</entry>
    <entry>Private use</entry>
  </row>
  <row>
    <entry>Cs</entry>
    <entry>Surrogate</entry>
  </row>
  <row>
    <entry>L</entry>
    <entry>Letter</entry>
  </row>
  <row>
    <entry>Ll</entry>
    <entry>Lower case letter</entry>
  </row>
  <row>
    <entry>Lm</entry>
    <entry>Modifier letter</entry>
  </row>
  <row>
    <entry>Lo</entry>
    <entry>Other letter</entry>
  </row>
  <row>
    <entry>Lt</entry>
    <entry>Title case letter</entry>
  </row>
  <row>
    <entry>Lu</entry>
    <entry>Upper case letter</entry>
  </row>
  <row>
    <entry>M</entry>
    <entry>Mark</entry>
  </row>
  <row>
    <entry>Mc</entry>
    <entry>Spacing mark</entry>
  </row>
  <row>
    <entry>Me</entry>
    <entry>Enclosing mark</entry>
  </row>
  <row>
    <entry>Mn</entry>
    <entry>Non-spacing mark</entry>
  </row>
  <row>
    <entry>N</entry>
    <entry>Number</entry>
  </row>
  <row>
    <entry>Nd</entry>
    <entry>Decimal number</entry>
  </row>
  <row>
    <entry>Nl</entry>
    <entry>Letter number</entry>
  </row>
  <row>
    <entry>No</entry>
    <entry>Other number</entry>
  </row>
  <row>
    <entry>P</entry>
    <entry>Punctuation</entry>
  </row>
  <row>
    <entry>Pc</entry>
    <entry>Connector punctuation</entry>
  </row>
  <row>
    <entry>Pd</entry>
    <entry>Dash punctuation</entry>
  </row>
  <row>
    <entry>Pe</entry>
    <entry>Close punctuation</entry>
  </row>
  <row>
    <entry>Pf</entry>
    <entry>Final punctuation</entry>
  </row>
  <row>
    <entry>Pi</entry>
    <entry>Initial punctuation</entry>
  </row>
  <row>
    <entry>Po</entry>
    <entry>Other punctuation</entry>
  </row>
  <row>
    <entry>Ps</entry>
    <entry>Open punctuation</entry>
  </row>
  <row>
    <entry>S</entry>
    <entry>Symbol</entry>
  </row>
  <row>
    <entry>Sc</entry>
    <entry>Currency symbol</entry>
  </row>
  <row>
    <entry>Sk</entry>
    <entry>Modifier symbol</entry>
  </row>
  <row>
    <entry>Sm</entry>
    <entry>Mathematical symbol</entry>
  </row>
  <row>
    <entry>So</entry>
    <entry>Other symbol</entry>
  </row>
  <row>
    <entry>Z</entry>
    <entry>Separator</entry>
  </row>
  <row>
    <entry>Zl</entry>
    <entry>Line separator</entry>
  </row>
  <row>
    <entry>Zp</entry>
    <entry>Paragraph separator</entry>
  </row>
  <row>
    <entry>Zs</entry>
    <entry>Space separator</entry>
  </row>
</tbody>
</tgroup>
</table>

<para>
The special property L&amp; is also supported: it matches a character that has
the Lu, Ll, or Lt property, in other words, a letter that is not classified as
a modifier or "other".
</para>

<para>
The long synonyms for these properties that Perl supports (such as \ep{Letter})
are not supported by GRegex, nor is it permitted to prefix any of these
properties with "Is".
</para>

<para>
No character that is in the Unicode table has the Cn (unassigned) property.
Instead, this property is assumed for any code point that is not in the
Unicode table.
</para>

<para>
Specifying caseless matching does not affect these escape sequences.
For example, \p{Lu} always matches only upper case letters.
</para>

<para>
The \X escape matches any number of Unicode characters that form an
extended Unicode sequence. \X is equivalent to
</para>

<programlisting>
(?&gt;\PM\pM*)
</programlisting>

<para>
That is, it matches a character without the "mark" property, followed
by zero or more characters with the "mark" property, and treats the
sequence as an atomic group (see below). Characters with the "mark"
property are typically accents that affect the preceding character.
</para>

<para>
Matching characters by Unicode property is not fast, because GRegex has
to search a structure that contains data for over fifteen thousand
characters. That is why the traditional escape sequences such as \d and
\w do not use Unicode properties.
</para>
</refsect2>

<refsect2>
<title>Simple assertions</title>
<para>
The final use of backslash is for certain simple assertions. An
assertion specifies a condition that has to be met at a particular point in
a match, without consuming any characters from the string. The
use of subpatterns for more complicated assertions is described below.
The backslashed assertions are:
</para>

<table frame="all" colsep="1" rowsep="1">
<title>Simple assertions</title>
<tgroup cols="2">
<colspec colnum="1" align="center"/>
<thead>