forked from boostorg/optional
Refs #3395. Optional construction and assignment now works correctly for types with overridden operator&. Also silenced some GCC warnings about broken strict aliasing rules.
[SVN r67020]
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@ -11,12 +11,12 @@
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//
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// Revisions:
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// 27 Apr 2008 (improved swap) Fernando Cacciola, Niels Dekker, Thorsten Ottosen
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//
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//
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#ifndef BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP
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#define BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP
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#include<new>
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#include<algorithm>
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#include <new>
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#include <algorithm>
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#include "boost/config.hpp"
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#include "boost/assert.hpp"
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@ -31,6 +31,7 @@
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#include "boost/mpl/not.hpp"
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#include "boost/detail/reference_content.hpp"
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#include "boost/none.hpp"
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#include "boost/utility/addressof.hpp"
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#include "boost/utility/compare_pointees.hpp"
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#include "boost/utility/in_place_factory.hpp"
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@ -110,7 +111,12 @@ template <class T>
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class aligned_storage
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{
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// Borland ICEs if unnamed unions are used for this!
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union dummy_u
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union
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#if defined(__GNUC__) && !defined(__INTEL_COMPILER)
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// This works around GCC warnings about breaking strict aliasing rules when casting storage address to T*
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__attribute__((may_alias))
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#endif
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dummy_u
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{
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char data[ sizeof(T) ];
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BOOST_DEDUCED_TYPENAME type_with_alignment<
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@ -119,8 +125,13 @@ class aligned_storage
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public:
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void const* address() const { return &dummy_.data[0]; }
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void * address() { return &dummy_.data[0]; }
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#if defined(__GNUC__) && !defined(__INTEL_COMPILER)
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void const* address() const { return &dummy_; }
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void * address() { return &dummy_; }
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#else
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void const* address() const { return dummy_.data; }
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void * address() { return dummy_.data; }
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#endif
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} ;
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template<class T>
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@ -154,7 +165,7 @@ class optional_base : public optional_tag
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typedef
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#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
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BOOST_DEDUCED_TYPENAME
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#endif
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#endif
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::boost::detail::make_reference_content<T>::type internal_type ;
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typedef aligned_storage<internal_type> storage_type ;
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@ -205,7 +216,7 @@ class optional_base : public optional_tag
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{
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construct(val);
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}
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// Creates an optional<T> initialized with 'val' IFF cond is true, otherwise creates an uninitialzed optional<T>.
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// Can throw if T::T(T const&) does
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optional_base ( bool cond, argument_type val )
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@ -426,8 +437,22 @@ class optional_base : public optional_tag
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private :
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// internal_type can be either T or reference_content<T>
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#if defined(__GNUC__) && !defined(__INTEL_COMPILER)
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// This workaround is supposed to silence GCC warnings about broken strict aliasing rules
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internal_type const* get_object() const
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{
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union { void const* ap_pvoid; internal_type const* as_ptype; } caster = { m_storage.address() };
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return caster.as_ptype;
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}
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internal_type * get_object()
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{
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union { void* ap_pvoid; internal_type* as_ptype; } caster = { m_storage.address() };
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return caster.as_ptype;
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}
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#else
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internal_type const* get_object() const { return static_cast<internal_type const*>(m_storage.address()); }
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internal_type * get_object() { return static_cast<internal_type *> (m_storage.address()); }
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#endif
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// reference_content<T> lacks an implicit conversion to T&, so the following is needed to obtain a proper reference.
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reference_const_type dereference( internal_type const* p, is_not_reference_tag ) const { return *p ; }
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@ -518,7 +543,7 @@ class optional : public optional_detail::optional_base<T>
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// Depending on the above some T ctor is called.
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// Can throw is the resolved T ctor throws.
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template<class Expr>
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explicit optional ( Expr const& expr ) : base(expr,&expr) {}
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explicit optional ( Expr const& expr ) : base(expr,boost::addressof(expr)) {}
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#endif
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// Creates a deep copy of another optional<T>
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@ -532,9 +557,9 @@ class optional : public optional_detail::optional_base<T>
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// Assigns from an expression. See corresponding constructor.
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// Basic Guarantee: If the resolved T ctor throws, this is left UNINITIALIZED
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template<class Expr>
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optional& operator= ( Expr expr )
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optional& operator= ( Expr const& expr )
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{
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this->assign_expr(expr,&expr);
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this->assign_expr(expr,boost::addressof(expr));
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return *this ;
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}
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#endif
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@ -595,7 +620,7 @@ class optional : public optional_detail::optional_base<T>
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// Returns a copy of the value if this is initialized, 'v' otherwise
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reference_const_type get_value_or ( reference_const_type v ) const { return this->is_initialized() ? get() : v ; }
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reference_type get_value_or ( reference_type v ) { return this->is_initialized() ? get() : v ; }
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// Returns a pointer to the value if this is initialized, otherwise,
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// the behaviour is UNDEFINED
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// No-throw
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@ -612,22 +637,22 @@ class optional : public optional_detail::optional_base<T>
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// No-throw
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operator unspecified_bool_type() const { return this->safe_bool() ; }
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// This is provided for those compilers which don't like the conversion to bool
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// on some contexts.
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bool operator!() const { return !this->is_initialized() ; }
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// This is provided for those compilers which don't like the conversion to bool
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// on some contexts.
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bool operator!() const { return !this->is_initialized() ; }
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} ;
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// Returns optional<T>(v)
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template<class T>
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inline
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template<class T>
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inline
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optional<T> make_optional ( T const& v )
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{
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return optional<T>(v);
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}
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// Returns optional<T>(cond,v)
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template<class T>
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inline
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template<class T>
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inline
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optional<T> make_optional ( bool cond, T const& v )
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{
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return optional<T>(cond,v);
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