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jzmaddock a550507517 Update installation instructions for icu. 
Regenerate docs.
Fixes: https://github.com/boostorg/regex/issues/89.
2019-10-26 10:51:25 +01:00

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<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_regex.background.standards"></a><a class="link" href="standards.html" title="Standards Conformance">Standards Conformance</a>
</h3></div></div></div>
<h5>
<a name="boost_regex.background.standards.h0"></a>
<span class="phrase"><a name="boost_regex.background.standards.c"></a></span><a class="link" href="standards.html#boost_regex.background.standards.c">C++</a>
</h5>
<p>
Boost.Regex is intended to conform to the <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1836.pdf" target="_top">Technical
Report on C++ Library Extensions</a>.
</p>
<h5>
<a name="boost_regex.background.standards.h1"></a>
<span class="phrase"><a name="boost_regex.background.standards.ecmascript_javascript"></a></span><a class="link" href="standards.html#boost_regex.background.standards.ecmascript_javascript">ECMAScript
/ JavaScript</a>
</h5>
<p>
All of the ECMAScript regular expression syntax features are supported, except
that:
</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>
<h5>
<a name="boost_regex.background.standards.h2"></a>
<span class="phrase"><a name="boost_regex.background.standards.perl"></a></span><a class="link" href="standards.html#boost_regex.background.standards.perl">Perl</a>
</h5>
<p>
Almost all Perl features are supported, except for:
</p>
<p>
(?{code}) Not implementable in a compiled strongly typed language.
</p>
<p>
(??{code}) Not implementable in a compiled strongly typed language.
</p>
<p>
(*VERB) The <a href="http://perldoc.perl.org/perlre.html#Special-Backtracking-Control-Verbs" target="_top">backtracking
control verbs</a> are not recognised or implemented at this time.
</p>
<p>
In addition the following features behave slightly differently from Perl:
</p>
<p>
^ $ \Z These recognise any line termination sequence, and not just \n: see
the Unicode requirements below.
</p>
<h5>
<a name="boost_regex.background.standards.h3"></a>
<span class="phrase"><a name="boost_regex.background.standards.posix"></a></span><a class="link" href="standards.html#boost_regex.background.standards.posix">POSIX</a>
</h5>
<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>
<h5>
<a name="boost_regex.background.standards.h4"></a>
<span class="phrase"><a name="boost_regex.background.standards.unicode"></a></span><a class="link" href="standards.html#boost_regex.background.standards.unicode">Unicode</a>
</h5>
<p>
The following comments refer to <a href="http://unicode.org/reports/tr18/" target="_top">Unicode
Technical Standard #18: Unicode Regular Expressions version 11</a>.
</p>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Item
</p>
</th>
<th>
<p>
Feature
</p>
</th>
<th>
<p>
Support
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
1.1
</p>
</td>
<td>
<p>
Hex Notation
</p>
</td>
<td>
<p>
Yes: use \x{DDDD} to refer to code point UDDDD.
</p>
</td>
</tr>
<tr>
<td>
<p>
1.2
</p>
</td>
<td>
<p>
Character Properties
</p>
</td>
<td>
<p>
All the names listed under the General Category Property are supported.
Script names and Other Names are not currently supported.
</p>
</td>
</tr>
<tr>
<td>
<p>
1.3
</p>
</td>
<td>
<p>
Subtraction and Intersection
</p>
</td>
<td>
<p>
Indirectly support by forward-lookahead:
</p>
<p>
<code class="computeroutput"><span class="special">(?=[[:</span><span class="identifier">X</span><span class="special">:]])[[:</span><span class="identifier">Y</span><span class="special">:]]</span></code>
</p>
<p>
Gives the intersection of character properties X and Y.
</p>
<p>
<code class="computeroutput"><span class="special">(?![[:</span><span class="identifier">X</span><span class="special">:]])[[:</span><span class="identifier">Y</span><span class="special">:]]</span></code>
</p>
<p>
Gives everything in Y that is not in X (subtraction).
</p>
</td>
</tr>
<tr>
<td>
<p>
1.4
</p>
</td>
<td>
<p>
Simple Word Boundaries
</p>
</td>
<td>
<p>
Conforming: non-spacing marks are included in the set of word characters.
</p>
</td>
</tr>
<tr>
<td>
<p>
1.5
</p>
</td>
<td>
<p>
Caseless Matching
</p>
</td>
<td>
<p>
Supported, note that at this level, case transformations are 1:1,
many to many case folding operations are not supported (for example
"&#223;" to "SS").
</p>
</td>
</tr>
<tr>
<td>
<p>
1.6
</p>
</td>
<td>
<p>
Line Boundaries
</p>
</td>
<td>
<p>
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.
</p>
</td>
</tr>
<tr>
<td>
<p>
1.7
</p>
</td>
<td>
<p>
Code Points
</p>
</td>
<td>
<p>
Supported: provided you use the u32* algorithms, then UTF-8, UTF-16
and UTF-32 are all treated as sequences of 32-bit code points.
</p>
</td>
</tr>
<tr>
<td>
<p>
2.1
</p>
</td>
<td>
<p>
Canonical Equivalence
</p>
</td>
<td>
<p>
Not supported: it is up to the user of the library to convert all
text into the same canonical form as the regular expression.
</p>
</td>
</tr>
<tr>
<td>
<p>
2.2
</p>
</td>
<td>
<p>
Default Grapheme Clusters
</p>
</td>
<td>
<p>
Not supported.
</p>
</td>
</tr>
<tr>
<td>
<p>
2.3Default Word Boundaries
</p>
</td>
<td>
<p>
Not supported.
</p>
</td>
<td class="auto-generated">&#160;</td>
</tr>
<tr>
<td>
<p>
2.4
</p>
</td>
<td>
<p>
Default Loose Matches
</p>
</td>
<td>
<p>
Not Supported.
</p>
</td>
</tr>
<tr>
<td>
<p>
2.5
</p>
</td>
<td>
<p>
Named Properties
</p>
</td>
<td>
<p>
Supported: the expression "[[:name:]]" or \N{name} matches
the named character "name".
</p>
</td>
</tr>
<tr>
<td>
<p>
2.6
</p>
</td>
<td>
<p>
Wildcard properties
</p>
</td>
<td>
<p>
Not Supported.
</p>
</td>
</tr>
<tr>
<td>
<p>
3.1
</p>
</td>
<td>
<p>
Tailored Punctuation.
</p>
</td>
<td>
<p>
Not Supported.
</p>
</td>
</tr>
<tr>
<td>
<p>
3.2
</p>
</td>
<td>
<p>
Tailored Grapheme Clusters
</p>
</td>
<td>
<p>
Not Supported.
</p>
</td>
</tr>
<tr>
<td>
<p>
3.3
</p>
</td>
<td>
<p>
Tailored Word Boundaries.
</p>
</td>
<td>
<p>
Not Supported.
</p>
</td>
</tr>
<tr>
<td>
<p>
3.4
</p>
</td>
<td>
<p>
Tailored Loose Matches
</p>
</td>
<td>
<p>
Partial support: [[=c=]] matches characters with the same primary
equivalence class as "c".
</p>
</td>
</tr>
<tr>
<td>
<p>
3.5
</p>
</td>
<td>
<p>
Tailored Ranges
</p>
</td>
<td>
<p>
Supported: [a-b] matches any character that collates in the range
a to b, when the expression is constructed with the collate flag
set.
</p>
</td>
</tr>
<tr>
<td>
<p>
3.6
</p>
</td>
<td>
<p>
Context Matches
</p>
</td>
<td>
<p>
Not Supported.
</p>
</td>
</tr>
<tr>
<td>
<p>
3.7
</p>
</td>
<td>
<p>
Incremental Matches
</p>
</td>
<td>
<p>
Supported: pass the flag <code class="computeroutput"><span class="identifier">match_partial</span></code>
to the regex algorithms.
</p>
</td>
</tr>
<tr>
<td>
<p>
3.8
</p>
</td>
<td>
<p>
Unicode Set Sharing
</p>
</td>
<td>
<p>
Not Supported.
</p>
</td>
</tr>
<tr>
<td>
<p>
3.9
</p>
</td>
<td>
<p>
Possible Match Sets
</p>
</td>
<td>
<p>
Not supported, however this information is used internally to optimise
the matching of regular expressions, and return quickly if no match
is possible.
</p>
</td>
</tr>
<tr>
<td>
<p>
3.10
</p>
</td>
<td>
<p>
Folded Matching
</p>
</td>
<td>
<p>
Partial Support: It is possible to achieve a similar effect by
using a custom regular expression traits class.
</p>
</td>
</tr>
<tr>
<td>
<p>
3.11
</p>
</td>
<td>
<p>
Custom Submatch Evaluation
</p>
</td>
<td>
<p>
Not Supported.
</p>
</td>
</tr>
</tbody>
</table></div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright &#169; 1998-2013 John Maddock<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
</p>
</div></td>
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