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Merged value_initialized::swap from trunk [48424] and [48425], according to ticket #2243, as was agreed with Fernando Cacciola.

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[SVN r49967]
This commit is contained in:
Niels Dekker 2008-11-27 19:37:39 +00:00
parent 633832e872
commit 9e73b2c6ae
3 changed files with 63 additions and 5 deletions
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13
include/boost/utility/value_init.hpp
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@ -7,6 +7,7 @@
// 21 Ago 2002 (Created) Fernando Cacciola
// 24 Dec 2007 (Refactored and worked around various compiler bugs) Fernando Cacciola, Niels Dekker
// 23 May 2008 (Fixed operator= const issue, added initialized_value) Niels Dekker, Fernando Cacciola
// 21 Ago 2008 (Added swap) Niels Dekker, Fernando Cacciola
//
#ifndef BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
#define BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
@ -22,6 +23,7 @@
#include <boost/static_assert.hpp>
#include <boost/type_traits/cv_traits.hpp>
#include <boost/type_traits/alignment_of.hpp>
#include <boost/swap.hpp>
#include <cstring>
#include <new>
@ -93,6 +95,11 @@ class value_initialized
return wrapper_address()->data;
}
void swap(value_initialized & arg)
{
::boost::swap( this->data(), arg.data() );
}
operator T&() const { return this->data(); }
} ;
@ -110,6 +117,12 @@ T& get ( value_initialized<T>& x )
return x.data() ;
}
template<class T>
void swap ( value_initialized<T> & lhs, value_initialized<T> & rhs )
{
lhs.swap(rhs) ;
}
class initialized_value_t
{

8
value_init.htm
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@ -253,7 +253,7 @@ its internal data, prior to constructing the object that it contains.
<h2><a name="val_init"><code>template class value_initialized&lt;T&gt;</code></a></h2>
<pre>namespace boost {<br><br>template&lt;class T&gt;<br>class value_initialized<br>{<br> public :<br> value_initialized() : x() {}<br> operator T&amp;() const { return x ; }<br> T&amp; data() const { return x ; }<br><br> private :<br> <i>unspecified</i> x ;<br>} ;<br><br>template&lt;class T&gt;<br>T const&amp; get ( value_initialized&lt;T&gt; const&amp; x )<br>{<br> return x.data() ;<br>}<br><br>template&lt;class T&gt;<br>T&amp; get ( value_initialized&lt;T&gt;&amp; x )<br>{<br> return x.data() ;<br>}<br><br>} // namespace boost<br></pre>
<pre>namespace boost {<br><br>template&lt;class T&gt;<br>class value_initialized<br>{<br> public :<br> value_initialized() : x() {}<br> operator T&amp;() const { return x ; }<br> T&amp; data() const { return x ; }<br> void swap( value_initialized&lt;T&gt;&amp; );<br><br> private :<br> <i>unspecified</i> x ;<br>} ;<br><br>template&lt;class T&gt;<br>T const&amp; get ( value_initialized&lt;T&gt; const&amp; x )<br>{<br> return x.data() ;<br>}<br><br>template&lt;class T&gt;<br>T&amp; get ( value_initialized&lt;T&gt;&amp; x )<br>{<br> return x.data() ;<br>}<br><br>} // namespace boost<br></pre>
<p>An object of this template class is a <code>T</code>-wrapper convertible
to <code>'T&amp;'</code> whose wrapped object (data member of type <code>T</code>)
@ -277,6 +277,10 @@ non-member function <code>get()</code>: </p>
Mutable objects can be modified directly from within the wrapper but constant
objects cannot:</p>
<p>When <code>T</code> is a <em>Swappable</em> type, <code>value_initialized&lt;T&gt;</code>
is swappable as well, by calling its <code>swap</code> member function
as well as by calling <code>boost::swap</code>.</p>
<pre>value_initialized&lt;int&gt; x ; <br>static_cast&lt;int&amp;&gt;(x) = 1 ; // OK<br>get(x) = 1 ; // OK<br><br>value_initialized&lt;int const&gt; y ; <br>static_cast&lt;int&amp;&gt;(y) = 1 ; // ERROR: cannot cast to int&amp;<br>static_cast&lt;int const&amp;&gt;(y) = 1 ; // ERROR: cannot modify a const value<br>get(y) = 1 ; // ERROR: cannot modify a const value</pre>
<h3>Warning:</h3>
@ -379,7 +383,7 @@ for Boost release version 1.35 (2008), offering a workaround to various compiler
</p>
<hr>
<p>Revised 23 May 2008</p>
<p>Revised 28 August 2008</p>
<p>&copy; Copyright Fernando Cacciola, 2002, 2008.</p>

41
value_init_test.cpp
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@ -9,6 +9,7 @@
// 21 Ago 2002 (Created) Fernando Cacciola
// 15 Jan 2008 (Added tests regarding compiler issues) Fernando Cacciola, Niels Dekker
// 23 May 2008 (Added tests regarding initialized_value) Niels Dekker
// 21 Ago 2008 (Added swap test) Niels Dekker
#include <cstring> // For memcmp.
#include <iostream>
@ -181,6 +182,35 @@ struct CopyFunctionCallTester
};
//
// A struct that allows testing whether its customized swap function is called.
//
struct SwapFunctionCallTester
{
bool is_custom_swap_called;
int data;
SwapFunctionCallTester()
: is_custom_swap_called(false), data(0) {}
SwapFunctionCallTester(const SwapFunctionCallTester & arg)
: is_custom_swap_called(false), data(arg.data) {}
void swap(SwapFunctionCallTester & arg)
{
std::swap(data, arg.data);
is_custom_swap_called = true;
arg.is_custom_swap_called = true;
}
};
void swap(SwapFunctionCallTester & lhs, SwapFunctionCallTester & rhs)
{
lhs.swap(rhs);
}
template<class T>
void check_initialized_value ( T const& y )
{
@ -323,9 +353,20 @@ int test_main(int, char **)
BOOST_CHECK ( ! get(copyFunctionCallTester3).is_copy_constructed);
BOOST_CHECK ( get(copyFunctionCallTester3).is_assignment_called);
boost::value_initialized<SwapFunctionCallTester> swapFunctionCallTester1;
boost::value_initialized<SwapFunctionCallTester> swapFunctionCallTester2;
get(swapFunctionCallTester1).data = 1;
get(swapFunctionCallTester2).data = 2;
boost::swap(swapFunctionCallTester1, swapFunctionCallTester2);
BOOST_CHECK( get(swapFunctionCallTester1).data == 2 );
BOOST_CHECK( get(swapFunctionCallTester2).data == 1 );
BOOST_CHECK( get(swapFunctionCallTester1).is_custom_swap_called );
BOOST_CHECK( get(swapFunctionCallTester2).is_custom_swap_called );
return 0;
}
unsigned int expected_failures = 0;