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<h1 align="center">Boost.Regex</h1>
<h2 align="center">class match_results</h2>
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<h3>Contents</h3>
<dl class="index">
<dt><A href="#synopsis">Synopsis</A> <dt><A href="#description">Description</A> </dt>
</dl>
<h3><a name="synopsis"></a>Synopsis</h3>
<p>#include &lt;<A href="../../../boost/regex.hpp">boost/regex.hpp</A>&gt;</p>
<p>Regular expressions are different from many simple pattern-matching algorithms
in that as well as finding an overall match they can also produce
sub-expression matches: each sub-expression being delimited in the pattern by a
pair of parenthesis (...). There has to be some method for reporting
sub-expression matches back to the user: this is achieved this by defining a
class <i>match_results</i> that acts as an indexed collection of sub-expression
matches, each sub-expression match being contained in an object of type <i><A href="sub_match.html">
sub_match</A></i> .</p>
<p>Template class match_results denotes a collection of character sequences
representing the result of a regular expression match. Objects of type
match_results are passed to the algorithms <A href="regex_match.html">regex_match</A>
and <A href="regex_search.html">regex_search</A>, and are returned by the
iterator <A href="regex_iterator.html">regex_iterator</A> .&nbsp; Storage for
the collection is allocated and freed as necessary by the member functions of
class match_results.</p>
<p>The template class match_results conforms to the requirements of a Sequence, as
specified in (lib.sequence.reqmts), except that only operations defined for
const-qualified Sequences are supported.</p>
<p>Class template match_results is most commonly used as one of the typedefs
cmatch, wcmatch, smatch, or wsmatch:</p>
<pre>template &lt;class BidirectionalIterator,
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class Allocator = allocator&lt;sub_match&lt;BidirectionalIterator&gt; &gt;
class match_results;
typedef match_results&lt;const char*&gt; cmatch;
typedef match_results&lt;const wchar_t*&gt; wcmatch;
typedef match_results&lt;string::const_iterator&gt; smatch;
typedef match_results&lt;wstring::const_iterator&gt; wsmatch;
template &lt;class BidirectionalIterator,
class Allocator = allocator&lt;sub_match&lt;BidirectionalIterator&gt; &gt;
class match_results
{
public:
typedef sub_match&lt;BidirectionalIterator&gt; value_type;
typedef const value_type&amp; const_reference;
typedef const_reference reference;
typedef implementation defined const_iterator;
typedef const_iterator iterator;
typedef typename iterator_traits&lt;BidirectionalIterator&gt;::difference_type difference_type;
typedef typename Allocator::size_type size_type;
typedef Allocator allocator_type;
typedef typename iterator_traits&lt;BidirectionalIterator&gt;::value_type char_type;
typedef basic_string&lt;char_type&gt; string_type;
// construct/copy/destroy:
explicit <A href="#c1" >match_results</A>(const Allocator&amp; a = Allocator());
<A href="#c2" >match_results</A>(const match_results&amp; m);
<A href="#c3" >match_results</A>&amp; <A href="#c3" >operator</A>=(const match_results&amp; m);
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~match_results();
// size:
size_type <A href="#m1" >size</A>() const;
size_type <A href="#m2" >max_size</A>() const;
bool <A href="#m3" >empty</A>() const;
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// element access:
difference_type <A href="#m4" >length</A>(int sub = 0) const;
difference_type <A href="#m5" >position</A>(unsigned int sub = 0) const;
string_type <A href="#m6" >str</A>(int sub = 0) const;
const_reference <A href="#m7" >operator</A>[](int n) const;
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const_reference <A href="#m8" >prefix</A>() const;
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const_reference <A href="#m9" >suffix</A>() const;
const_iterator <A href="#m10" >begin</A>() const;
const_iterator <A href="#m11" >end</A>() const;
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// format:
template &lt;class OutputIterator&gt;
OutputIterator <A href="#m12" >format</A>(OutputIterator out,
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const string_type&amp; fmt,
match_flag_type flags = format_default) const;
string_type <A href="#m13" >format</A>(const string_type&amp; fmt,
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match_flag_type flags = format_default) const;
allocator_type <A href="#m14" >get_allocator</A>() const;
void <A href="#m15" >swap</A>(match_results&amp; that);
#ifdef BOOST_REGEX_MATCH_EXTRA
typedef typename value_type::capture_sequence_type <A href="#m16" >capture_sequence_type</A>;
const capture_sequence_type&amp; <A href="#m17" >captures</A>(std::size_t i)const;
#endif
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};
template &lt;class BidirectionalIterator, class Allocator&gt;
bool <A href="#n1" >operator</A> == (const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1,
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const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2);
template &lt;class BidirectionalIterator, class Allocator&gt;
bool <A href="#n2" >operator</A> != (const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1,
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const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2);
template &lt;class charT, class traits, class BidirectionalIterator, class Allocator&gt;
basic_ostream&lt;charT, traits&gt;&amp;
<A href="#n3" >operator</A> &lt;&lt; (basic_ostream&lt;charT, traits&gt;&amp; os,
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const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m);
template &lt;class BidirectionalIterator, class Allocator&gt;
void <A href="#n4" >swap</A>(match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1,
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match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2);
</pre>
<h3><a name="description"></a>Description</h3>
<h4>match_results constructors</h4>
<p>In all <code>match_results</code> constructors, a copy of the Allocator
argument is used for any memory allocation performed by the constructor or
member functions during the lifetime of the object.</p>
<pre><A name=c1></A>
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match_results(const Allocator&amp; a = Allocator());
</pre>
<b></b>
<p><b>Effects:</b> Constructs an object of class match_results. The postconditions
of this function are indicated in the table:</p>
<p align="center"></p>
<center>
<table id="Table2" cellSpacing="1" cellPadding="7" width="624" border="1">
<tbody>
<tr>
<td vAlign="top" width="50%"><b></b>
<p><b>Element</b></p>
</td>
<td vAlign="top" width="50%"><b></b>
<p><b>Value</b></p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>empty()</p>
</td>
<td vAlign="top" width="50%">
<p>true</p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>size()</p>
</td>
<td vAlign="top" width="50%">
<p>0</p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>str()</p>
</td>
<td vAlign="top" width="50%">
<p>basic_string&lt;charT&gt;()</p>
</td>
</tr>
</tbody></table>
</center>
<p>&nbsp;</p>
<pre><A name=c2></A>
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match_results(const match_results&amp; m);
</pre>
<b></b>
<p><b>Effects:</b> Constructs an object of class match_results, as a copy of m.</p>
<pre><A name=c3></A>
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match_results&amp; operator=(const match_results&amp; m);
</pre>
<b></b>
<p><b>Effects:</b> Assigns m to *this. The postconditions of this function are
indicated in the table:</p>
<p align="center"></p>
<center>
<table id="Table3" cellSpacing="1" cellPadding="7" width="624" border="1">
<tbody>
<tr>
<td vAlign="top" width="50%"><b></b>
<p><b>Element</b></p>
</td>
<td vAlign="top" width="50%"><b></b>
<p><b>Value</b></p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>empty()</p>
</td>
<td vAlign="top" width="50%">
<p>m.empty().</p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>size()</p>
</td>
<td vAlign="top" width="50%">
<p>m.size().</p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>str(n)</p>
</td>
<td vAlign="top" width="50%">
<p>m.str(n) for all integers n &lt; m.size().</p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>prefix()</p>
</td>
<td vAlign="top" width="50%">
<p>m.prefix().</p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>suffix()</p>
</td>
<td vAlign="top" width="50%">
<p>m.suffix().</p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>(*this)[n]</p>
</td>
<td vAlign="top" width="50%">
<p>m[n] for all integers n &lt; m.size().</p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>length(n)</p>
</td>
<td vAlign="top" width="50%">
<p>m.length(n) for all integers n &lt; m.size().</p>
</td>
</tr>
<tr>
<td vAlign="top" width="50%">
<p>position(n)</p>
</td>
<td vAlign="top" width="50%">
<p>m.position(n) for all integers n &lt; m.size().</p>
</td>
</tr>
</tbody></table>
</center>
<h4>match_results size</h4>
<pre><A name=m1></A>
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size_type size()const;
</pre>
<b></b>
<p><b>Effects:</b> Returns the number of sub_match elements stored in *this; that
is the number of marked sub-expressions in the regular expression that was
matched plus one.</p>
<pre><A name=m2></A>
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size_type max_size()const;
</pre>
<b></b>
<p><b>Effects:</b> Returns the maximum number of sub_match elements that can be
stored in *this.</p>
<pre><A name=m3></A>
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bool empty()const;
</pre>
<b></b>
<p><b>Effects:</b> Returns <code>size() == 0</code>.</p>
<h4>match_results element access</h4>
<pre><A name=m4></A>
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difference_type length(int sub = 0)const;
</pre>
<b></b>
<p><b>Effects:</b> Returns the length of sub-expression <EM>sub</EM>, that is to
say: <code>(*this)[sub].length()</code>.</p>
<pre><A name=m5></A>
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difference_type position(unsigned int sub = 0)const;
</pre>
<b></b>
<p><b>Effects:</b> Returns the starting location of sub-expression <EM>sub</EM>,
or -1 if <EM>sub</EM> was not matched <code>.</code></p>
<pre><A name=m6></A>
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string_type str(int sub = 0)const;
</pre>
<b></b>
<p><b>Effects:</b> Returns sub-expression <EM>sub</EM> as a string:&nbsp; <code>string_type((*this)[sub]).</code></p>
<pre><A name=m7></A>
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const_reference operator[](int n) const;
</pre>
<b></b>
<p><b>Effects:</b> Returns a reference to the <code>sub_match</code> object
representing the character sequence that matched marked sub-expression <i>n</i>.
If <code>n == 0</code> then returns a reference to a <code>sub_match</code> object
representing the character sequence that matched the whole regular
expression.&nbsp; If <EM>n</EM> is out of range, or if <EM>n</EM> is an
unmatched sub-expression, then returns a sub_match object whose <EM>matched</EM>
member is <EM>false</EM>.</p>
<pre><A name=m8></A>
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const_reference prefix()const;
</pre>
<b></b>
<p><b>Effects:</b> Returns a reference to the <code>sub_match</code> object
representing the character sequence from the start of the string being
matched/searched, to the start of the match found.</p>
<pre><A name=m9></A>
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const_reference suffix()const;
</pre>
<b></b>
<p><b>Effects:</b> Returns a reference to the <code>sub_match</code> object
representing the character sequence from the end of the match found to the end
of the string being matched/searched.</p>
<pre><A name=m10></A>
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const_iterator begin()const;
</pre>
<b></b>
<p><b>Effects:</b> Returns a starting iterator that enumerates over all the marked
sub-expression matches stored in *this.</p>
<pre><A name=m11></A>
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const_iterator end()const;
</pre>
<b></b>
<p><b>Effects:</b> Returns a terminating iterator that enumerates over all the
marked sub-expression matches stored in *this.</p>
<h4><A name="format"></A>match_results reformatting</h4>
<pre>template &lt;class OutputIterator&gt;
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OutputIterator format(OutputIterator out,
const string_type&amp; fmt,
<A href="match_flag_type.html" >match_flag_type</A> flags = format_default);
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</pre>
<b></b>
<p><b>Requires:</b> The type OutputIterator conforms to the Output Iterator
requirements (24.1.2).</p>
<b></b>
<p><b>Effects:</b> Copies the character sequence <i>[fmt.begin(), fmt.end())</i> to
OutputIterator <i>out</i>. For each format specifier or escape sequence in <i>fmt</i>,
replace that sequence with either the character(s) it represents, or the
sequence of characters within *this to which it refers. The bitmasks specified
in <i><A href="match_flag_type.html">flags</A></i> determines what <A href="format_syntax.html">
format specifiers or escape sequences are recognized</A>, by default this is
the format used by ECMA-262, ECMAScript Language Specification, Chapter 15 part
5.4.11 String.prototype.replace.</p>
<b></b>
<p><b>Returns:</b> <i>out</i>.</p>
<pre><A name=m13></A>
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string_type format(const string_type&amp; fmt,
<A href="match_flag_type.html" >match_flag_type</A> flags = format_default);
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</pre>
<b></b>
<p><b>Effects:</b> Returns a copy of the string <i>fmt</i>. For each format
specifier or escape sequence in <i>fmt</i>, replace that sequence with either
the character(s) it represents, or the sequence of characters within *this to
which it refers. The bitmasks specified in <i><A href="match_flag_type.html">flags</A></i>
determines what <A href="format_syntax.html">format specifiers or escape sequences
are recognized</A>, by default this is the format used by ECMA-262,
ECMAScript Language Specification, Chapter 15 part 5.4.11
String.prototype.replace.</p>
<H4>Allocator access</H4>
<pre>allocator_type get_allocator()const;
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</pre>
<b></b>
<p><b>Effects:</b> Returns a copy of the Allocator that was passed to the object's
constructor.</p>
<H4><A name="m15"></A>Swap</H4>
<PRE>void swap(match_results&amp; that);
</PRE>
<b></b>
<p><b>Effects:</b> Swaps the contents of the two sequences.</p>
<b></b>
<p><b>Postcondition:</b> <code>*this</code> contains the sequence of matched
sub-expressions that were in <code>that</code>, <code>that</code> contains the
sequence of matched sub-expressions that were in <code>*this</code>.</p>
<b></b>
<p><b>Complexity:</b> constant time.</p>
<H4>Captures</H4>
<PRE><A name=m16></A>typedef typename value_type::capture_sequence_type capture_sequence_type;</PRE>
<P>Defines an implementation-specific type that&nbsp;satisfies the requirements of
a standard library Sequence (21.1.1 including the optional Table 68
operations),&nbsp;whose value_type is a <EM>sub_match&lt;BidirectionalIterator&gt;</EM>.&nbsp;This
type happens to be <EM>std::vector&lt;sub_match&lt;BidirectionalIterator&gt; &gt;</EM>,
but you shouldn't actually rely on that.</P>
<PRE><A name=m17></A>const capture_sequence_type&amp; <A href="#m8" >captures</A>(std::size_t i)const; </PRE>
<P><STRONG>Effects:</STRONG> returns a sequence containing all the captures
obtained for sub-expression <EM>i</EM>.</P>
<P><STRONG>Returns:</STRONG> <code>(*this)[i].captures();</code></P>
<P><STRONG>Preconditions:</STRONG> the library must be built and used with
BOOST_REGEX_MATCH_EXTRA defined, and you must pass the flag <A href="match_flag_type.html">
match_extra</A> to the regex matching functions (<A href="regex_match.html">regex_match</A>,
<A href="regex_search.html">regex_search</A>, <A href="regex_iterator.html">regex_iterator</A>
or <A href="regex_token_iterator.html">regex_token_iterator</A>) in order for
this member function to be defined and return useful information.</P>
<P><STRONG>Rationale:</STRONG> Enabling this feature has several consequences:
</P>
<UL>
<LI>
sub_match occupies more memory resulting in complex expressions running out of
memory or stack space more quickly during matching.
<LI>
The matching algorithms are less efficient at handling some features
(independent sub-expressions for example), even when match_extra is not used.
<LI>
The matching algorithms are much less efficient (i.e. slower), when match_extra
is used.&nbsp; Mostly this is down to the extra memory allocations that have to
take place.</LI></UL>
<h4>match_results non-members</h4>
<PRE><A name=n1></A>template &lt;class BidirectionalIterator, class Allocator&gt;
bool operator == (const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1,
const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2);</PRE>
<P><B>Effects:</B> Compares the two sequences for equality.</P>
<PRE><A name=n2></A>template &lt;class BidirectionalIterator, class Allocator&gt;
bool operator != (const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1,
const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2);</PRE>
<P><B>Effects:</B> Compares the two sequences for inequality.</P>
<PRE><A name=n3></A>template &lt;class charT, class traits, class BidirectionalIterator, class Allocator&gt;
basic_ostream&lt;charT, traits&gt;&amp;
operator &lt;&lt; (basic_ostream&lt;charT, traits&gt;&amp; os,
const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m);</PRE>
<P><B>Effects:</B> Writes the contents of <EM>m</EM> to the stream <EM>os</EM> as
if by calling <code>os &lt;&lt; m.str();</code> Returns <EM>os</EM>..</P>
<PRE><A name=n4></A>template &lt;class BidirectionalIterator, class Allocator&gt;
void swap(match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1,
match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2);</PRE>
<P><B>Effects:</B> Swaps the contents of the two sequences.</P>
<p></p>
<hr>
<p>Revised
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->
2003-10-24 10:51:38 +00:00
24 Oct 2003
<!--webbot bot="Timestamp" endspan i-checksum="39359" --></p>
2003-10-24 10:51:38 +00:00
<p><i><EFBFBD> Copyright John Maddock&nbsp;1998-
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%Y" startspan --> 2003<!--webbot bot="Timestamp" endspan i-checksum="39359" --></i></p>
2003-10-24 10:51:38 +00:00
<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>
</body>
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</html>