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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Boost.Regex: Standards Conformance</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<link rel="stylesheet" type="text/css" href="../../../boost.css">
</head>
<body>
<P>
<TABLE id="Table1" cellSpacing="1" cellPadding="1" width="100%" border="0">
<TR>
<td valign="top" width="300">
<h3><a href="../../../index.htm"><img height="86" width="277" alt="C++ Boost" src="../../../boost.png" border="0"></a></h3>
</td>
<TD width="353">
<H1 align="center">Boost.Regex</H1>
<H2 align="center">Standards Conformance</H2>
</TD>
<td width="50">
<h3><a href="index.html"><img height="45" width="43" alt="Boost.Regex Index" src="uarrow.gif" border="0"></a></h3>
</td>
</TR>
</TABLE>
</P>
<HR>
<H3>C++</H3>
<P>Boost.regex is intended to conform to the <A href="http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/papers/2003/n1429.htm">
regular expression standardization proposal</A>, which will appear in a
future C++ standard technical report (and hopefully in a future version of the
standard). </P>
<H3>ECMAScript / JavaScript</H3>
<P>All of the ECMAScript regular expression syntax features are supported, except
that:</P>
<P>Negated class escapes (\S, \D and \W) are not permitted inside character class
definitions ( [...] ).</P>
<P>The escape sequence \u matches any upper case character (the same as
[[:upper:]]) rather than a Unicode escape sequence; use \x{DDDD} for
Unicode escape sequences.</P>
<H3>Perl</H3>
<P>Almost all Perl features are supported, except for:</P>
<P>
<TABLE id="Table2" cellSpacing="1" cellPadding="1" width="100%" border="0">
<TR>
<TD>(?{code})</TD>
<TD>Not implementable in a compiled strongly typed language.</TD>
</TR>
<TR>
<TD>(??{code})</TD>
<TD>Not implementable in a compiled strongly typed language.</TD>
</TR>
</TABLE>
</P>
<H3>POSIX</H3>
<P>All the POSIX basic and extended regular expression features are supported,
except that:</P>
<P>No character collating names are recognized except those specified in the POSIX
standard for the C locale, unless they are explicitly registered with the
traits class.</P>
<P>Character equivalence classes ( [[=a=]] etc) are probably buggy except on
Win32. Implementing this feature requires knowledge of the format of the
string sort keys produced by the system; if you need this, and the default
implementation doesn't work on your platform, then you will need to supply a
custom traits class.</P>
<H3>Unicode</H3>
<P>The following comments refer to <A href="http://www.unicode.org/reports/tr18/">Unicode
Technical
<SPAN>Standard
</SPAN>#18: Unicode Regular Expressions</A> version 9.</P>
<P>
<TABLE id="Table3" cellSpacing="1" cellPadding="1" width="100%" border="0">
<TR>
<TD>#</TD>
<TD>Feature</TD>
<TD>Support</TD>
</TR>
<TR>
<TD>1.1</TD>
<TD>Hex Notation</TD>
<TD>Yes: use \x{DDDD} to refer to code point UDDDD.</TD>
</TR>
<TR>
<TD>1.2</TD>
<TD>Character Properties</TD>
<TD>All the names listed under the <A href="http://www.unicode.org/reports/tr18/#Categories">General
Category Property</A> are supported. Script names and Other Names are
not currently supported.</TD>
</TR>
<TR>
<TD>1.3</TD>
<TD><A name="Subtraction_and_Intersection">Subtraction</A> and Intersection</TD>
<TD>
<P>Indirectly support by forward-lookahead:
</P>
<P>(?=[[:X:]])[[:Y:]]</P>
<P>Gives the intersection of character properties X and Y.</P>
<P>(?![[:X:]])[[:Y:]]</P>
<P>Gives everything in Y that is not in X (subtraction).</P>
</TD>
</TR>
<TR>
<TD>1.4</TD>
<TD><A name="Simple_Word_Boundaries">Simple Word Boundaries</A></TD>
<TD>Conforming: non-spacing marks are included in the set of word characters.</TD>
</TR>
<TR>
<TD>1.5</TD>
<TD>Caseless Matching</TD>
<TD>Supported, note that at this level, case transformations are 1:1, many to many
case folding operations are not supported (for example "" to "SS").</TD>
</TR>
<TR>
<TD>1.6</TD>
<TD>Line Boundaries</TD>
<TD>Supported, except that "." matches only one character of "\r\n". Other than
that word boundaries match correctly; including not matching in the middle of a
"\r\n" sequence.</TD>
</TR>
<TR>
<TD>1.7</TD>
<TD>Code Points</TD>
<TD>Supported: provided you use the <A href="icu_strings.html">u32* algorithms</A>,
then UTF-8, UTF-16 and UTF-32 are all treated as sequences of 32-bit code
points.</TD>
</TR>
<TR>
<TD>2.1</TD>
<TD>Canonical Equivalence</TD>
<TD>Not supported: it is up to the user of the library to convert all text into
the same canonical form as the regular expression.</TD>
</TR>
<TR>
<TD>2.2</TD>
<TD>Default Grapheme Clusters</TD>
<TD>Not supported.</TD>
</TR>
<TR>
<TD>2.3</TD>
<TD><!--StartFragment -->
<P><A name="Default_Word_Boundaries">Default Word Boundaries</A></P>
</TD>
<TD>Not supported.</TD>
</TR>
<TR>
<TD>2.4</TD>
<TD><!--StartFragment -->
<P><A name="Default_Loose_Matches">Default Loose Matches</A></P>
</TD>
<TD>Not Supported.</TD>
</TR>
<TR>
<TD>2.5</TD>
<TD>Name Properties</TD>
<TD>Supported: the expression "[[:name:]]" or \N{name} matches the named character
"name".</TD>
</TR>
<TR>
<TD>2.6</TD>
<TD>Wildcard properties</TD>
<TD>Not Supported.</TD>
</TR>
<TR>
<TD>3.1</TD>
<TD>Tailored Punctuation.</TD>
<TD>Not Supported.</TD>
</TR>
<TR>
<TD>3.2</TD>
<TD>Tailored Grapheme Clusters</TD>
<TD>Not Supported.</TD>
</TR>
<TR>
<TD>3.3</TD>
<TD>Tailored Word Boundaries.</TD>
<TD>Not Supported.</TD>
</TR>
<TR>
<TD>3.4</TD>
<TD>Tailored Loose Matches</TD>
<TD>Partial support: [[=c=]] matches characters with the same primary equivalence
class as "c".</TD>
</TR>
<TR>
<TD>3.5</TD>
<TD>Tailored Ranges</TD>
<TD>Supported: [a-b] matches any character that collates in the range a to b, when
the expression is constructed with the <A href="syntax_option_type.html">collate</A>
flag set.</TD>
</TR>
<TR>
<TD>3.6</TD>
<TD>Context Matches</TD>
<TD>Not Supported.</TD>
</TR>
<TR>
<TD>3.7</TD>
<TD>Incremental Matches</TD>
<TD>Supported: pass the flag <A href="match_flag_type.html">match_partial</A> to
the regex algorithms.</TD>
</TR>
<TR>
<TD>3.8</TD>
<TD>Unicode Set Sharing</TD>
<TD>Not Supported.</TD>
</TR>
<TR>
<TD>3.9</TD>
<TD>Possible Match Sets</TD>
<TD>Not supported, however this information is used internally to optimise the
matching of regular expressions, and return quickly if no match is possible.</TD>
</TR>
<TR>
<TD>3.10</TD>
<TD>Folded Matching</TD>
<TD>Partial Support: It is possible to achieve a similar effect by using a
custom regular expression traits class.</TD>
</TR>
<TR>
<TD>3.11</TD>
<TD>Custom Submatch Evaluation</TD>
<TD>Not Supported.</TD>
</TR>
</TABLE>
</P>
<HR>
<p>Revised
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->
28 June 2004
<!--webbot bot="Timestamp" endspan i-checksum="39359" --></p>
<p><i> Copyright John Maddock 1998-
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%Y" startspan --> 2004<!--webbot bot="Timestamp" endspan i-checksum="39359" --></i></p>
<P><I>Use, modification and distribution are subject to the Boost Software License,
Version 1.0. (See accompanying file <A href="../../../LICENSE_1_0.txt">LICENSE_1_0.txt</A>
or copy at <A href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>)</I></P>
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