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trivially-copyable optional<T> for trivial T

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Andrzej Krzemienski
2017-10-28 16:51:13 +02:00
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29
doc/1A_on_performance.qbk
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@ -1,7 +1,7 @@

[section Performance considerations]
Technical details aside, the memory layout of `optional<T>` is more-less this:
Technical details aside, the memory layout of `optional<T>` for a generic `T` is more-less this:
template <typename T>
class optional
@ -9,8 +9,33 @@ Technical details aside, the memory layout of `optional<T>` is more-less this:
bool _initialized;
std::aligned_storage_t<sizeof(t), alignof(T)> _storage;
};
Lifetime of the `T` inside `_storage` is manually controlled with placement-`new`s and pseudo-destructor calls. However, for trivial `T`s we use a different way of storage, by simply holding a `T`:
But for the purpose of this analysis, considering memory layouts, we can think of it as:
template <typename T>
class optional
{
bool _initialized;
T _storage;
};
We call it a ['direct] storage. This makes `optional<T>` a trivially-copyable type for trivial `T`s. This only works for compilers that support defaulted functions and type traits. On compilers without defaulted functions we still use the direct storage, but `optional<T>` is no longer recognized as trivially-copyable. On compilers that do not fully support type traits, we still use the direct storage for scalar types, but we leave the programmer a way of customizing her type, so that it is reconized by `optional` as trivial, by specializing type trait `boost::opitonal_config::is_type_trivial`:
struct X // not trivial
{
X() {}
};
namespace boost { namespace optional_config {
template <> struct is_type_trivial<X> : boost::true_type {};
}}
[heading Controlling the size]
For the purpose of the followin analysis, considering memory layouts, we can think of it as:
template <typename T>
class optional

5
doc/91_relnotes.qbk
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@ -11,6 +11,11 @@
[section:relnotes Release Notes]
[heading Boost Release 1.66]
* On newer compilers `optional` is now trivially-copyable for trivial `T`s. This uses a different storage (just `T` rather than `aligned_storage`). We require the compiler to support defaulted functions and type traits. Otherwise, we still use the the plain storage for scalar types.
[heading Boost Release 1.63]
* Added two new in-place constructors. They work similarly to `emplace()` functions: they initialize the contained value by perfect-forwarding the obtained arguments. One constructor always initializes the contained value, the other based on a boolean condition.
* Syntax `o = {}` now correctly un-initializes optional, just like in `std::optional`.

27
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@ -28,6 +28,19 @@
</h2></div></div></div>
<h4>
<a name="boost_optional.relnotes.h0"></a>
<span class="phrase"><a name="boost_optional.relnotes.boost_release_1_66"></a></span><a class="link" href="relnotes.html#boost_optional.relnotes.boost_release_1_66">Boost
Release 1.66</a>
</h4>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
On newer compilers <code class="computeroutput"><span class="identifier">optional</span></code>
is now trivially-copyable for trivial <code class="computeroutput"><span class="identifier">T</span></code>s.
This uses a different storage (just <code class="computeroutput"><span class="identifier">T</span></code>
rather than <code class="computeroutput"><span class="identifier">aligned_storage</span></code>).
We require the compiler to support defaulted functions and type traits.
Otherwise, we still use the the plain storage for scalar types.
</li></ul></div>
<h4>
<a name="boost_optional.relnotes.h1"></a>
<span class="phrase"><a name="boost_optional.relnotes.boost_release_1_63"></a></span><a class="link" href="relnotes.html#boost_optional.relnotes.boost_release_1_63">Boost
Release 1.63</a>
</h4>
@ -51,7 +64,7 @@
</li>
</ul></div>
<h4>
<a name="boost_optional.relnotes.h1"></a>
<a name="boost_optional.relnotes.h2"></a>
<span class="phrase"><a name="boost_optional.relnotes.boost_release_1_62"></a></span><a class="link" href="relnotes.html#boost_optional.relnotes.boost_release_1_62">Boost
Release 1.62</a>
</h4>
@ -59,7 +72,7 @@
Fixed <a href="https://svn.boost.org/trac/boost/ticket/12179" target="_top">Trac #12179</a>.
</li></ul></div>
<h4>
<a name="boost_optional.relnotes.h2"></a>
<a name="boost_optional.relnotes.h3"></a>
<span class="phrase"><a name="boost_optional.relnotes.boost_release_1_61"></a></span><a class="link" href="relnotes.html#boost_optional.relnotes.boost_release_1_61">Boost
Release 1.61</a>
</h4>
@ -102,7 +115,7 @@
</li>
</ul></div>
<h4>
<a name="boost_optional.relnotes.h3"></a>
<a name="boost_optional.relnotes.h4"></a>
<span class="phrase"><a name="boost_optional.relnotes.boost_release_1_60"></a></span><a class="link" href="relnotes.html#boost_optional.relnotes.boost_release_1_60">Boost
Release 1.60</a>
</h4>
@ -113,7 +126,7 @@
#11203</a>.
</li></ul></div>
<h4>
<a name="boost_optional.relnotes.h4"></a>
<a name="boost_optional.relnotes.h5"></a>
<span class="phrase"><a name="boost_optional.relnotes.boost_release_1_59"></a></span><a class="link" href="relnotes.html#boost_optional.relnotes.boost_release_1_59">Boost
Release 1.59</a>
</h4>
@ -127,7 +140,7 @@
</li>
</ul></div>
<h4>
<a name="boost_optional.relnotes.h5"></a>
<a name="boost_optional.relnotes.h6"></a>
<span class="phrase"><a name="boost_optional.relnotes.boost_release_1_58"></a></span><a class="link" href="relnotes.html#boost_optional.relnotes.boost_release_1_58">Boost
Release 1.58</a>
</h4>
@ -163,7 +176,7 @@
</li>
</ul></div>
<h4>
<a name="boost_optional.relnotes.h6"></a>
<a name="boost_optional.relnotes.h7"></a>
<span class="phrase"><a name="boost_optional.relnotes.boost_release_1_57"></a></span><a class="link" href="relnotes.html#boost_optional.relnotes.boost_release_1_57">Boost
Release 1.57</a>
</h4>
@ -173,7 +186,7 @@
to fix C++03 compile error on <code class="computeroutput"><span class="identifier">logic_error</span><span class="special">(</span><span class="string">"..."</span><span class="special">)</span></code>"</em></span>.
</li></ul></div>
<h4>
<a name="boost_optional.relnotes.h7"></a>
<a name="boost_optional.relnotes.h8"></a>
<span class="phrase"><a name="boost_optional.relnotes.boost_release_1_56"></a></span><a class="link" href="relnotes.html#boost_optional.relnotes.boost_release_1_56">Boost
Release 1.56</a>
</h4>

51
doc/html/boost_optional/tutorial/performance_considerations.html
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@ -29,7 +29,8 @@
</h3></div></div></div>
<p>
Technical details aside, the memory layout of <code class="computeroutput"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code>
is more-less this:
for a generic <code class="computeroutput"><span class="identifier">T</span></code> is more-less
this:
</p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">optional</span>
@ -39,8 +40,50 @@
<span class="special">};</span>
</pre>
<p>
But for the purpose of this analysis, considering memory layouts, we can
think of it as:
Lifetime of the <code class="computeroutput"><span class="identifier">T</span></code> inside
<code class="computeroutput"><span class="identifier">_storage</span></code> is manually controlled
with placement-<code class="computeroutput"><span class="keyword">new</span></code>s and pseudo-destructor
calls. However, for trivial <code class="computeroutput"><span class="identifier">T</span></code>s
we use a different way of storage, by simply holding a <code class="computeroutput"><span class="identifier">T</span></code>:
</p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">optional</span>
<span class="special">{</span>
<span class="keyword">bool</span> <span class="identifier">_initialized</span><span class="special">;</span>
<span class="identifier">T</span> <span class="identifier">_storage</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
We call it a <span class="emphasis"><em>direct</em></span> storage. This makes <code class="computeroutput"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> a
trivially-copyable type for trivial <code class="computeroutput"><span class="identifier">T</span></code>s.
This only works for compilers that support defaulted functions and type traits.
On compilers without defaulted functions we still use the direct storage,
but <code class="computeroutput"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> is
no longer recognized as trivially-copyable. On compilers that do not fully
support type traits, we still use the direct storage for scalar types, but
we leave the programmer a way of customizing her type, so that it is reconized
by <code class="computeroutput"><span class="identifier">optional</span></code> as trivial, by
specializing type trait <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">opitonal_config</span><span class="special">::</span><span class="identifier">is_type_trivial</span></code>:
</p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">X</span> <span class="comment">// not trivial</span>
<span class="special">{</span>
<span class="identifier">X</span><span class="special">()</span> <span class="special">{}</span>
<span class="special">};</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">optional_config</span> <span class="special">{</span>
<span class="keyword">template</span> <span class="special">&lt;&gt;</span> <span class="keyword">struct</span> <span class="identifier">is_type_trivial</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;</span> <span class="special">:</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">true_type</span> <span class="special">{};</span>
<span class="special">}}</span>
</pre>
<h5>
<a name="boost_optional.tutorial.performance_considerations.h0"></a>
<span class="phrase"><a name="boost_optional.tutorial.performance_considerations.controlling_the_size"></a></span><a class="link" href="performance_considerations.html#boost_optional.tutorial.performance_considerations.controlling_the_size">Controlling
the size</a>
</h5>
<p>
For the purpose of the followin analysis, considering memory layouts, we
can think of it as:
</p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">optional</span>
@ -143,7 +186,7 @@
<span class="inlinemediaobject"><img src="../../images/opt_align4.png" alt="opt_align4"></span>
</p>
<h5>
<a name="boost_optional.tutorial.performance_considerations.h0"></a>
<a name="boost_optional.tutorial.performance_considerations.h1"></a>
<span class="phrase"><a name="boost_optional.tutorial.performance_considerations.optional_function_parameters"></a></span><a class="link" href="performance_considerations.html#boost_optional.tutorial.performance_considerations.optional_function_parameters">Optional
function parameters</a>
</h5>

2
doc/html/index.html
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@ -146,7 +146,7 @@
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"><p><small>Last revised: May 17, 2017 at 23:01:39 GMT</small></p></td>
<td align="left"><p><small>Last revised: October 28, 2017 at 14:38:14 GMT</small></p></td>
<td align="right"><div class="copyright-footer"></div></td>
</tr></table>
<hr>

499
include/boost/optional/detail/optional_trivially_copyable_base.hpp Normal file
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@ -0,0 +1,499 @@
// trivilally-copyable version of the storage
template<class T>
class tc_optional_base : public optional_tag
{
private :
typedef tc_optional_base<T> this_type ;
protected :
typedef T value_type ;
protected:
typedef T & reference_type ;
typedef T const& reference_const_type ;
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
typedef T && rval_reference_type ;
typedef T && reference_type_of_temporary_wrapper ;
#endif
typedef T * pointer_type ;
typedef T const* pointer_const_type ;
typedef T const& argument_type ;
tc_optional_base()
:
m_initialized(false) {}
tc_optional_base ( none_t )
:
m_initialized(false) {}
tc_optional_base ( argument_type val )
:
m_initialized(true), m_storage(val) {}
tc_optional_base ( bool cond, argument_type val )
:
m_initialized(cond), m_storage(val) {}
// tc_optional_base ( tc_optional_base const& ) = default;
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
template<class Expr, class PtrExpr>
explicit tc_optional_base ( Expr&& expr, PtrExpr const* tag )
:
m_initialized(false)
{
construct(boost::forward<Expr>(expr),tag);
}
#else
// This is used for both converting and in-place constructions.
// Derived classes use the 'tag' to select the appropriate
// implementation (the correct 'construct()' overload)
template<class Expr>
explicit tc_optional_base ( Expr const& expr, Expr const* tag )
:
m_initialized(false)
{
construct(expr,tag);
}
#endif
// tc_optional_base& operator= ( tc_optional_base const& ) = default;
// ~tc_optional_base() = default;
// Assigns from another optional<T> (deep-copies the rhs value)
void assign ( tc_optional_base const& rhs )
{
this->operator=(rhs);
}
// Assigns from another _convertible_ optional<U> (deep-copies the rhs value)
template<class U>
void assign ( optional<U> const& rhs )
{
if ( rhs.is_initialized() )
#ifndef BOOST_OPTIONAL_CONFIG_RESTORE_ASSIGNMENT_OF_NONCONVERTIBLE_TYPES
m_storage = rhs.get();
#else
m_storage = static_cast<value_type>(rhs.get());
#endif
m_initialized = rhs.is_initialized();
}
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// move-assigns from another _convertible_ optional<U> (deep-moves from the rhs value)
template<class U>
void assign ( optional<U>&& rhs )
{
typedef BOOST_DEDUCED_TYPENAME optional<U>::rval_reference_type ref_type;
if ( rhs.is_initialized() )
m_storage = static_cast<ref_type>(rhs.get());
m_initialized = rhs.is_initialized();
}
#endif
void assign ( argument_type val )
{
construct(val);
}
void assign ( none_t ) { destroy(); }
#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
template<class Expr, class ExprPtr>
void assign_expr ( Expr&& expr, ExprPtr const* tag )
{
construct(boost::forward<Expr>(expr),tag);
}
#else
template<class Expr>
void assign_expr ( Expr const& expr, Expr const* tag )
{
construct(expr,tag);
}
#endif
#endif
public :
// **DEPPRECATED** Destroys the current value, if any, leaving this UNINITIALIZED
// No-throw (assuming T::~T() doesn't)
void reset() BOOST_NOEXCEPT { destroy(); }
// **DEPPRECATED** Replaces the current value -if any- with 'val'
void reset ( argument_type val ) BOOST_NOEXCEPT { assign(val); }
// Returns a pointer to the value if this is initialized, otherwise,
// returns NULL.
// No-throw
pointer_const_type get_ptr() const { return m_initialized ? get_ptr_impl() : 0 ; }
pointer_type get_ptr() { return m_initialized ? get_ptr_impl() : 0 ; }
bool is_initialized() const { return m_initialized ; }
protected :
void construct ( argument_type val )
{
m_storage = val ;
m_initialized = true ;
}
#if (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES) && (!defined BOOST_NO_CXX11_VARIADIC_TEMPLATES)
// Constructs in-place
// upon exception *this is always uninitialized
template<class... Args>
void construct ( in_place_init_t, Args&&... args )
{
m_storage = value_type( boost::forward<Args>(args)... ) ;
m_initialized = true ;
}
template<class... Args>
void emplace_assign ( Args&&... args )
{
construct(in_place_init, boost::forward<Args>(args)...);
}
template<class... Args>
explicit tc_optional_base ( in_place_init_t, Args&&... args )
:
m_initialized(false)
{
construct(in_place_init, boost::forward<Args>(args)...);
}
template<class... Args>
explicit tc_optional_base ( in_place_init_if_t, bool cond, Args&&... args )
:
m_initialized(false)
{
if ( cond )
construct(in_place_init, boost::forward<Args>(args)...);
}
#elif (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES)
template<class Arg>
void construct ( in_place_init_t, Arg&& arg )
{
m_storage = value_type( boost::forward<Arg>(arg) );
m_initialized = true ;
}
void construct ( in_place_init_t )
{
m_storage = value_type();
m_initialized = true ;
}
template<class Arg>
void emplace_assign ( Arg&& arg )
{
construct(in_place_init, boost::forward<Arg>(arg)) ;
}
void emplace_assign ()
{
construct(in_place_init) ;
}
template<class Arg>
explicit tc_optional_base ( in_place_init_t, Arg&& arg )
:
m_initialized(false)
{
construct(in_place_init, boost::forward<Arg>(arg));
}
explicit tc_optional_base ( in_place_init_t )
:
m_initialized(false), m_storage() {}
template<class Arg>
explicit tc_optional_base ( in_place_init_if_t, bool cond, Arg&& arg )
:
m_initialized(false)
{
if ( cond )
construct(in_place_init, boost::forward<Arg>(arg));
}
explicit tc_optional_base ( in_place_init_if_t, bool cond )
:
m_initialized(false)
{
if ( cond )
construct(in_place_init);
}
#else
template<class Arg>
void construct ( in_place_init_t, const Arg& arg )
{
m_storage = value_type( arg );
m_initialized = true ;
}
template<class Arg>
void construct ( in_place_init_t, Arg& arg )
{
m_storage = value_type( arg );
m_initialized = true ;
}
void construct ( in_place_init_t )
{
m_storage = value_type();
m_initialized = true ;
}
template<class Arg>
void emplace_assign ( const Arg& arg )
{
construct(in_place_init, arg);
}
template<class Arg>
void emplace_assign ( Arg& arg )
{
construct(in_place_init, arg);
}
void emplace_assign ()
{
construct(in_place_init);
}
template<class Arg>
explicit tc_optional_base ( in_place_init_t, const Arg& arg )
: m_initialized(false)
{
construct(in_place_init, arg);
}
template<class Arg>
explicit tc_optional_base ( in_place_init_t, Arg& arg )
: m_initialized(false)
{
construct(in_place_init, arg);
}
explicit tc_optional_base ( in_place_init_t )
: m_initialized(false)
{
construct(in_place_init);
}
template<class Arg>
explicit tc_optional_base ( in_place_init_if_t, bool cond, const Arg& arg )
: m_initialized(false)
{
if ( cond )
construct(in_place_init, arg);
}
template<class Arg>
explicit tc_optional_base ( in_place_init_if_t, bool cond, Arg& arg )
: m_initialized(false)
{
if ( cond )
construct(in_place_init, arg);
}
explicit tc_optional_base ( in_place_init_if_t, bool cond )
: m_initialized(false)
{
if ( cond )
construct(in_place_init);
}
#endif
#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// Constructs in-place using the given factory
template<class Expr>
void construct ( Expr&& factory, in_place_factory_base const* )
{
boost_optional_detail::construct<value_type>(factory, boost::addressof(m_storage));
m_initialized = true ;
}
// Constructs in-place using the given typed factory
template<class Expr>
void construct ( Expr&& factory, typed_in_place_factory_base const* )
{
factory.apply(boost::addressof(m_storage)) ;
m_initialized = true ;
}
template<class Expr>
void assign_expr_to_initialized ( Expr&& factory, in_place_factory_base const* tag )
{
destroy();
construct(factory,tag);
}
// Constructs in-place using the given typed factory
template<class Expr>
void assign_expr_to_initialized ( Expr&& factory, typed_in_place_factory_base const* tag )
{
destroy();
construct(factory,tag);
}
#else
// Constructs in-place using the given factory
template<class Expr>
void construct ( Expr const& factory, in_place_factory_base const* )
{
boost_optional_detail::construct<value_type>(factory, m_storage.address());
m_initialized = true ;
}
// Constructs in-place using the given typed factory
template<class Expr>
void construct ( Expr const& factory, typed_in_place_factory_base const* )
{
factory.apply(boost::addressof(m_storage)) ;
m_initialized = true ;
}
template<class Expr>
void assign_expr_to_initialized ( Expr const& factory, in_place_factory_base const* tag )
{
destroy();
construct(factory,tag);
}
// Constructs in-place using the given typed factory
template<class Expr>
void assign_expr_to_initialized ( Expr const& factory, typed_in_place_factory_base const* tag )
{
destroy();
construct(factory,tag);
}
#endif
#endif
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// Constructs using any expression implicitly convertible to the single argument
// of a one-argument T constructor.
// Converting constructions of optional<T> from optional<U> uses this function with
// 'Expr' being of type 'U' and relying on a converting constructor of T from U.
template<class Expr>
void construct ( Expr&& expr, void const* )
{
m_storage = value_type(boost::forward<Expr>(expr)) ;
m_initialized = true ;
}
// Assigns using a form any expression implicitly convertible to the single argument
// of a T's assignment operator.
// Converting assignments of optional<T> from optional<U> uses this function with
// 'Expr' being of type 'U' and relying on a converting assignment of T from U.
template<class Expr>
void assign_expr_to_initialized ( Expr&& expr, void const* )
{
assign_value( boost::forward<Expr>(expr) );
}
#else
// Constructs using any expression implicitly convertible to the single argument
// of a one-argument T constructor.
// Converting constructions of optional<T> from optional<U> uses this function with
// 'Expr' being of type 'U' and relying on a converting constructor of T from U.
template<class Expr>
void construct ( Expr const& expr, void const* )
{
m_storage = value_type(expr) ;
m_initialized = true ;
}
// Assigns using a form any expression implicitly convertible to the single argument
// of a T's assignment operator.
// Converting assignments of optional<T> from optional<U> uses this function with
// 'Expr' being of type 'U' and relying on a converting assignment of T from U.
template<class Expr>
void assign_expr_to_initialized ( Expr const& expr, void const* )
{
assign_value(expr);
}
#endif
#ifdef BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION
// BCB5.64 (and probably lower versions) workaround.
// The in-place factories are supported by means of catch-all constructors
// and assignment operators (the functions are parameterized in terms of
// an arbitrary 'Expr' type)
// This compiler incorrectly resolves the overload set and sinks optional<T> and optional<U>
// to the 'Expr'-taking functions even though explicit overloads are present for them.
// Thus, the following overload is needed to properly handle the case when the 'lhs'
// is another optional.
//
// For VC<=70 compilers this workaround dosen't work becasue the comnpiler issues and error
// instead of choosing the wrong overload
//
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// Notice that 'Expr' will be optional<T> or optional<U> (but not tc_optional_base<..>)
template<class Expr>
void construct ( Expr&& expr, optional_tag const* )
{
if ( expr.is_initialized() )
{
// An exception can be thrown here.
// It it happens, THIS will be left uninitialized.
m_storage = value_type(boost::move(expr.get())) ;
m_initialized = true ;
}
}
#else
// Notice that 'Expr' will be optional<T> or optional<U> (but not tc_optional_base<..>)
template<class Expr>
void construct ( Expr const& expr, optional_tag const* )
{
if ( expr.is_initialized() )
{
// An exception can be thrown here.
// It it happens, THIS will be left uninitialized.
m_storage = value_type(expr.get()) ;
m_initialized = true ;
}
}
#endif
#endif // defined BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION
void assign_value ( argument_type val ) { m_storage = val; }
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
void assign_value ( rval_reference_type val ) { m_storage = static_cast<rval_reference_type>(val); }
#endif
void destroy()
{
m_initialized = false;
}
reference_const_type get_impl() const { return m_storage ; }
reference_type get_impl() { return m_storage ; }
pointer_const_type get_ptr_impl() const { return boost::addressof(m_storage); }
pointer_type get_ptr_impl() { return boost::addressof(m_storage); }
private :
bool m_initialized ;
T m_storage ;
} ;

91
include/boost/optional/optional.hpp
View File

@ -1,5 +1,5 @@
// Copyright (C) 2003, 2008 Fernando Luis Cacciola Carballal.
// Copyright (C) 2014 - 2016 Andrzej Krzemienski.
// Copyright (C) 2014 - 2017 Andrzej Krzemienski.
//
// Use, modification, and distribution is subject to the Boost Software
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@ -36,13 +36,22 @@
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/type_traits/decay.hpp>
#include <boost/type_traits/has_trivial_copy.hpp>
#include <boost/type_traits/has_trivial_move_constructor.hpp>
#include <boost/type_traits/has_trivial_constructor.hpp>
#include <boost/type_traits/has_trivial_assign.hpp>
#include <boost/type_traits/has_trivial_move_assign.hpp>
#include <boost/type_traits/has_trivial_destructor.hpp>
#include <boost/type_traits/is_base_of.hpp>
#include <boost/type_traits/is_const.hpp>
#include <boost/type_traits/is_constructible.hpp>
#include <boost/type_traits/is_lvalue_reference.hpp>
#include <boost/type_traits/is_nothrow_move_assignable.hpp>
#include <boost/type_traits/is_nothrow_move_constructible.hpp>
#include <boost/type_traits/is_rvalue_reference.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/type_traits/is_volatile.hpp>
#include <boost/type_traits/is_scalar.hpp>
#include <boost/move/utility.hpp>
#include <boost/none.hpp>
#include <boost/utility/compare_pointees.hpp>
@ -178,6 +187,7 @@ class optional_base : public optional_tag
// Creates a deep move of another optional<T>
// Can throw if T::T(T&&) does
optional_base ( optional_base&& rhs )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value)
:
m_initialized(false)
{
@ -210,6 +220,20 @@ class optional_base : public optional_tag
#endif
optional_base& operator= ( optional_base const& rhs )
{
this->assign(rhs);
return *this;
}
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
optional_base& operator= ( optional_base && rhs )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value)
{
this->assign(static_cast<optional_base&&>(rhs));
return *this;
}
#endif
// No-throw (assuming T::~T() doesn't)
~optional_base() { destroy() ; }
@ -735,6 +759,10 @@ class optional_base : public optional_tag
storage_type m_storage ;
} ;
#include <boost/optional/detail/optional_trivially_copyable_base.hpp>
// definition of metafunciton is_optional_val_init_candidate
template <typename U>
struct is_optional_related
@ -776,13 +804,46 @@ struct is_optional_val_init_candidate
: boost::conditional< !is_optional_related<U>::value && is_convertible_to_T_or_factory<T, U>::value
, boost::true_type, boost::false_type>::type
{};
template <typename T>
struct is_type_trivially_copyable
: boost::conditional<(boost::has_trivial_copy_constructor<T>::value &&
boost::has_trivial_move_constructor<T>::value &&
boost::has_trivial_destructor<T>::value &&
boost::has_trivial_move_assign<T>::value &&
boost::has_trivial_assign<T>::value),
boost::true_type, boost::false_type>::type
{};
} // namespace optional_detail
namespace optional_config {
template <typename T>
struct is_type_trivial
: boost::conditional< (optional_detail::is_type_trivially_copyable<T>::value && boost::has_trivial_default_constructor<T>::value) ||
(boost::is_scalar<T>::value && !boost::is_const<T>::value && !boost::is_volatile<T>::value)
, boost::true_type, boost::false_type>::type
{};
} // namespace optional_config
#ifndef BOOST_OPTIONAL_CONFIG_NO_SPEC_FOR_TRIVIAL_TYPES
# define BOOST_OPTIONAL_BASE_TYPE(T) boost::conditional< optional_config::is_type_trivial<T>::value, \
optional_detail::tc_optional_base<T>, \
optional_detail::optional_base<T> \
>::type
#else
# define BOOST_OPTIONAL_BASE_TYPE(T) optional_detail::optional_base<T>
#endif
template<class T>
class optional : public optional_detail::optional_base<T>
class optional
: public BOOST_OPTIONAL_BASE_TYPE(T)
{
typedef optional_detail::optional_base<T> base ;
typedef typename BOOST_OPTIONAL_BASE_TYPE(T) base ;
public :
@ -842,7 +903,7 @@ class optional : public optional_detail::optional_base<T>
)
:
base()
{
{
if ( rhs.is_initialized() )
this->construct(rhs.get());
}
@ -893,15 +954,24 @@ class optional : public optional_detail::optional_base<T>
// Creates a deep copy of another optional<T>
// Can throw if T::T(T const&) does
#ifndef BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
optional ( optional const& ) = default;
#else
optional ( optional const& rhs ) : base( static_cast<base const&>(rhs) ) {}
#endif
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// Creates a deep move of another optional<T>
// Can throw if T::T(T&&) does
#ifndef BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
optional ( optional && rhs ) = default;
#else
optional ( optional && rhs )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value)
: base( boost::move(rhs) )
{}
#endif
#endif
@ -959,21 +1029,30 @@ class optional : public optional_detail::optional_base<T>
// Assigns from another optional<T> (deep-copies the rhs value)
// Basic Guarantee: If T::T( T const& ) throws, this is left UNINITIALIZED
// (NOTE: On BCB, this operator is not actually called and left is left UNMODIFIED in case of a throw)
#ifndef BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
optional& operator= ( optional const& rhs ) = default;
#else
optional& operator= ( optional const& rhs )
{
this->assign( static_cast<base const&>(rhs) ) ;
return *this ;
}
#endif
#ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
// Assigns from another optional<T> (deep-moves the rhs value)
#ifndef BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
optional& operator= ( optional && ) = default;
#else
optional& operator= ( optional && rhs )
BOOST_NOEXCEPT_IF(::boost::is_nothrow_move_constructible<T>::value && ::boost::is_nothrow_move_assignable<T>::value)
{
this->assign( static_cast<base &&>(rhs) ) ;
return *this ;
}
#endif
#endif
#endif // BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
#ifndef BOOST_NO_CXX11_UNIFIED_INITIALIZATION_SYNTAX

3
test/Jamfile.v2
View File

@ -1,7 +1,7 @@
# Boost.Optional Library test Jamfile
#
# Copyright (C) 2003, Fernando Luis Cacciola Carballal.
# Copyright (C) 2014 - 2016 Andrzej Krzemienski
# Copyright (C) 2014 - 2017 Andrzej Krzemienski
#
# Use, modification, and distribution is subject to the Boost Software
# License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@ -66,6 +66,7 @@ import testing ;
[ compile-fail optional_test_fail_io_without_io.cpp ]
[ compile-fail optional_test_fail_none_io_without_io.cpp ]
[ compile-fail optional_test_fail_convert_assign_of_enums.cpp ]
[ run optional_test_static_properties.cpp ]
[ run optional_xconfig_NO_PROPER_ASSIGN_FROM_CONST_INT_pass.cpp ]
[ run-fail optional_xconfig_NO_PROPER_ASSIGN_FROM_CONST_INT_fail.cpp ]
[ run optional_xconfig_NO_PROPER_CONVERT_FROM_CONST_INT_pass.cpp ]

140
test/optional_test_static_properties.cpp Normal file
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@ -0,0 +1,140 @@
// Copyright (C) 2017 Andrzej Krzemienski.
//
// Use, modification, and distribution is subject to the Boost Software
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/lib/optional for documentation.
//
// You are welcome to contact the author at:
// akrzemi1@gmail.com
#include "boost/optional/optional.hpp"
#ifdef __BORLANDC__
#pragma hdrstop
#endif
#include "boost/core/lightweight_test.hpp"
#include "boost/core/lightweight_test_trait.hpp"
#include "boost/type_traits/is_base_of.hpp"
#ifndef BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
#if (defined BOOST_HAS_TRIVIAL_MOVE_ASSIGN) && (defined BOOST_HAS_TRIVIAL_MOVE_CONSTRUCTOR) && (defined BOOST_HAS_TRIVIAL_CONSTRUCTOR) && (defined BOOST_HAS_TRIVIAL_COPY) && (defined BOOST_HAS_TRIVIAL_ASSIGN) && (defined BOOST_HAS_TRIVIAL_DESTRUCTOR)
#else
# define BOOST_OPTIONAL_NO_TRIVIALITY_DETECTION
#endif
struct PrivDefault
{
private: PrivDefault() {}
};
struct CustDefault
{
CustDefault() {}
};
struct CustomizedTrivial
{
CustomizedTrivial() {}
};
namespace boost { namespace optional_config {
template <> struct is_type_trivial<CustomizedTrivial> : boost::true_type {};
}}
struct CustDtor
{
~CustDtor() {}
};
struct NoDefault
{
explicit NoDefault(int) {}
};
struct Empty {};
template <typename T, typename U>
struct Aggregate { T t; U u; };
struct CustAssign
{
CustAssign& operator=(CustAssign const&) { return *this; }
};
struct CustMove
{
CustMove(CustMove &&) {}
};
void test_type_traits()
{
// this only tests if type traits are implemented correctly
BOOST_TEST_TRAIT_TRUE(( boost::optional_config::is_type_trivial<int> ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_config::is_type_trivial<double> ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_config::is_type_trivial<Empty> ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_config::is_type_trivial<Aggregate<int, double> > ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_config::is_type_trivial<Aggregate<Aggregate<Empty, int>, double> > ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_config::is_type_trivial<CustomizedTrivial> ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_config::is_type_trivial<PrivDefault> ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_config::is_type_trivial<NoDefault> ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_config::is_type_trivial<CustDefault> ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_config::is_type_trivial<Aggregate<int, CustDefault> > ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_config::is_type_trivial<CustDtor> ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_config::is_type_trivial<CustAssign> ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_config::is_type_trivial<CustMove> ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_config::is_type_trivial<Aggregate<int, CustMove> > ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<int> ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<double> ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<Empty> ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<Aggregate<int, double> > ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<Aggregate<Aggregate<Empty, int>, double> > ));
#ifndef BOOST_OPTIONAL_NO_TRIVIALITY_DETECTION
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<PrivDefault> ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<NoDefault> ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<CustDefault> ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<Aggregate<int, CustDefault> > ));
#endif
BOOST_TEST_TRAIT_FALSE(( boost::optional_detail::is_type_trivially_copyable<CustDtor> ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_detail::is_type_trivially_copyable<CustAssign> ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_detail::is_type_trivially_copyable<CustMove> ));
BOOST_TEST_TRAIT_FALSE(( boost::optional_detail::is_type_trivially_copyable<Aggregate<int, CustMove> > ));
}
void test_trivial_copyability()
{
BOOST_TEST_TRAIT_TRUE((boost::is_base_of<boost::optional_detail::tc_optional_base<int>, boost::optional<int> > ));
BOOST_TEST_TRAIT_TRUE((boost::is_base_of<boost::optional_detail::tc_optional_base<double>, boost::optional<double> > ));
BOOST_TEST_TRAIT_TRUE((boost::is_base_of<boost::optional_detail::tc_optional_base<CustomizedTrivial>, boost::optional<CustomizedTrivial> > ));
#ifndef BOOST_OPTIONAL_NO_TRIVIALITY_DETECTION
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<boost::optional<int> > ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<boost::optional<double> > ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<boost::optional<CustomizedTrivial> > ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<boost::optional<Empty> > ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<boost::optional<Aggregate<int, double> > > ));
BOOST_TEST_TRAIT_TRUE(( boost::optional_detail::is_type_trivially_copyable<boost::optional<Aggregate<Aggregate<Empty, int>, double> > > ));
#endif
}
#endif
int main()
{
#ifndef BOOST_NO_CXX11_DEFAULTED_FUNCTIONS
test_type_traits();
test_trivial_copyability();
#endif
return boost::report_errors();
}