feedc0de/boost_smart_ptr
1
0
Fork 0
forked from boostorg/smart_ptr
Code Pull Requests Activity

const_pointer_cast added.

Browse Source 
[SVN r19147]
This commit is contained in:
Peter Dimov
2003-07-16 11:51:12 +00:00
parent 7c36a640ae
commit 192970b3b8
5 changed files with 106 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
include/boost/intrusive_ptr.hpp
View File

@@ -220,6 +220,11 @@ template<class T, class U> intrusive_ptr<T> static_pointer_cast(intrusive_ptr<U>
return static_cast<T *>(p.get());
}
template<class T, class U> intrusive_ptr<T> const_pointer_cast(intrusive_ptr<U> const & p)
{
return const_cast<T *>(p.get());
}
template<class T, class U> intrusive_ptr<T> dynamic_pointer_cast(intrusive_ptr<U> const & p)
{
return dynamic_cast<T *>(p.get());

21
include/boost/shared_ptr.hpp
View File

@@ -48,6 +48,7 @@ namespace detail
{
struct static_cast_tag {};
struct const_cast_tag {};
struct dynamic_cast_tag {};
struct polymorphic_cast_tag {};
@@ -68,6 +69,16 @@ template<> struct shared_ptr_traits<void const>
typedef void reference;
};
template<> struct shared_ptr_traits<void volatile>
{
typedef void reference;
};
template<> struct shared_ptr_traits<void const volatile>
{
typedef void reference;
};
#endif
// enable_shared_from_this support
@@ -158,6 +169,11 @@ public:
{
}
template<class Y>
shared_ptr(shared_ptr<Y> const & r, detail::const_cast_tag): px(const_cast<element_type *>(r.px)), pn(r.pn)
{
}
template<class Y>
shared_ptr(shared_ptr<Y> const & r, detail::dynamic_cast_tag): px(dynamic_cast<element_type *>(r.px)), pn(r.pn)
{
@@ -351,6 +367,11 @@ template<class T, class U> shared_ptr<T> static_pointer_cast(shared_ptr<U> const
return shared_ptr<T>(r, detail::static_cast_tag());
}
template<class T, class U> shared_ptr<T> const_pointer_cast(shared_ptr<U> const & r)
{
return shared_ptr<T>(r, detail::const_cast_tag());
}
template<class T, class U> shared_ptr<T> dynamic_pointer_cast(shared_ptr<U> const & r)
{
return shared_ptr<T>(r, detail::dynamic_cast_tag());

10
intrusive_ptr.html
View File

@@ -100,6 +100,9 @@
template&lt;class T, class U&gt;
intrusive_ptr&lt;T&gt; <A href="#static_pointer_cast" >static_pointer_cast</A>(intrusive_ptr&lt;U&gt; const &amp; r); // never throws
template&lt;class T, class U&gt;
intrusive_ptr&lt;T&gt; <A href="#const_pointer_cast" >const_pointer_cast</A>(intrusive_ptr&lt;U&gt; const &amp; r); // never throws
template&lt;class T, class U&gt;
intrusive_ptr&lt;T&gt; <A href="#dynamic_pointer_cast" >dynamic_pointer_cast</A>(intrusive_ptr&lt;U&gt; const &amp; r); // never throws
@@ -250,6 +253,13 @@ intrusive_ptr &amp; operator=(T * r);</pre>
<P><B>Returns:</B> <code>intrusive_ptr&lt;T&gt;(static_cast&lt;T*&gt;(r.get()))</code>.</P>
<P><B>Throws:</B> nothing.</P>
</BLOCKQUOTE>
<h3><a name="const_pointer_cast">const_pointer_cast</a></h3>
<pre>template&lt;class T, class U&gt;
intrusive_ptr&lt;T&gt; const_pointer_cast(intrusive_ptr&lt;U&gt; const &amp; r); // never throws</pre>
<BLOCKQUOTE>
<P><B>Returns:</B> <code>intrusive_ptr&lt;T&gt;(const_cast&lt;T*&gt;(r.get()))</code>.</P>
<P><B>Throws:</B> nothing.</P>
</BLOCKQUOTE>
<h3><a name="dynamic_pointer_cast">dynamic_pointer_cast</a></h3>
<pre>template&lt;class T, class U&gt;
intrusive_ptr&lt;T&gt; dynamic_pointer_cast(intrusive_ptr&lt;U&gt; const &amp; r);</pre>

18
shared_ptr.htm
View File

@@ -142,6 +142,9 @@ void bad()
template&lt;class T, class U&gt;
shared_ptr&lt;T&gt; <A href="#static_pointer_cast" >static_pointer_cast</A>(shared_ptr&lt;U&gt; const &amp; r); // never throws
template&lt;class T, class U&gt;
shared_ptr&lt;T&gt; <A href="#const_pointer_cast" >const_pointer_cast</A>(shared_ptr&lt;U&gt; const &amp; r); // never throws
template&lt;class T, class U&gt;
shared_ptr&lt;T&gt; <A href="#dynamic_pointer_cast" >dynamic_pointer_cast</A>(shared_ptr&lt;U&gt; const &amp; r); // never throws
@@ -473,6 +476,21 @@ q = p;
<p>will eventually result in undefined behavior, attempting to delete the same
object twice.</p>
</BLOCKQUOTE>
<h3><a name="const_pointer_cast">const_pointer_cast</a></h3>
<pre>template&lt;class T, class U&gt;
shared_ptr&lt;T&gt; const_pointer_cast(shared_ptr&lt;U&gt; const &amp; r); // never throws</pre>
<BLOCKQUOTE>
<P><STRONG>Requires:</STRONG> The expression <code>const_cast&lt;T*&gt;(r.get())</code>
must be well-formed.</P>
<P><B>Returns:</B> If <b>r</b> is <i>empty</i>, an <i>empty</i> <b>shared_ptr&lt;T&gt;</b>;
otherwise, a <STRONG>shared_ptr&lt;T&gt;</STRONG> object that stores a copy of <code>
const_cast&lt;T*&gt;(r.get())</code> and <i>shares ownership</i> with <b>r</b>.</P>
<P><B>Throws:</B> nothing.</P>
<P><B>Notes:</B> the seemingly equivalent expression</P>
<p><code>shared_ptr&lt;T&gt;(const_cast&lt;T*&gt;(r.get()))</code></p>
<p>will eventually result in undefined behavior, attempting to delete the same
object twice.</p>
</BLOCKQUOTE>
<h3><a name="dynamic_pointer_cast">dynamic_pointer_cast</a></h3>
<pre>template&lt;class T, class U&gt;
shared_ptr&lt;T&gt; dynamic_pointer_cast(shared_ptr&lt;U&gt; const &amp; r);</pre>

52
test/shared_ptr_test.cpp
View File

@@ -2375,6 +2375,57 @@ void test()
} // namespace n_static_cast
namespace n_const_cast
{
struct X;
void test()
{
{
boost::shared_ptr<void const volatile> px;
boost::shared_ptr<void> px2 = boost::const_pointer_cast<void>(px);
BOOST_TEST(px2.get() == 0);
}
{
boost::shared_ptr<int const volatile> px;
boost::shared_ptr<int> px2 = boost::const_pointer_cast<int>(px);
BOOST_TEST(px2.get() == 0);
}
{
boost::shared_ptr<X const volatile> px;
boost::shared_ptr<X> px2 = boost::const_pointer_cast<X>(px);
BOOST_TEST(px2.get() == 0);
}
{
boost::shared_ptr<void const volatile> px(new int);
boost::shared_ptr<void> px2 = boost::const_pointer_cast<void>(px);
BOOST_TEST(px.get() == px2.get());
BOOST_TEST(!(px < px2 || px2 < px));
BOOST_TEST(px.use_count() == 2);
BOOST_TEST(px2.use_count() == 2);
}
{
boost::shared_ptr<int const volatile> px(new int);
boost::shared_ptr<int> px2 = boost::const_pointer_cast<int>(px);
BOOST_TEST(px.get() == px2.get());
BOOST_TEST(!(px < px2 || px2 < px));
BOOST_TEST(px.use_count() == 2);
BOOST_TEST(px2.use_count() == 2);
}
}
} // namespace n_const_cast
namespace n_dynamic_cast
{
@@ -3141,6 +3192,7 @@ int main()
n_swap::test();
n_comparison::test();
n_static_cast::test();
n_const_cast::test();
n_dynamic_cast::test();
n_map::test();