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Compiler compatibility fixes; Reference assignment changed (if the lhs is initialized, the assignment goes to the referenced object, thus the reference is not rebound)

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[SVN r20546]
This commit is contained in:
Fernando Cacciola
2003-10-29 15:45:12 +00:00
parent faa3c1962a
commit 3468bfb07f
1 changed files with 177 additions and 82 deletions
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259
include/boost/optional.hpp
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@ -43,7 +43,7 @@
// However, optional's ctor is _explicit_ and the assignemt shouldn't compile.
// Therefore, for VC6.0 templated assignment is disabled.
//
#define BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
#define BOOST_OPTIONAL_NO_CONVERTING_ASSIGNMENT
#endif
#if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
@ -53,9 +53,25 @@
// given to the non-templated version, making the class non-implicitely-copyable.
//
#define BOOST_OPTIONAL_NO_CONVERTING_COPY_CTOR
#endif
#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
// AFAICT only VC7.1 correctly resolves the overload set
// that includes the in-place factory taking functions,
// so for the other VC versions, in-place factory support
// is disabled
#define BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
#endif
#if BOOST_WORKAROUND(__BORLANDC__, <= 0x564)
// VC7.0 has the following bug:
// When both a non-template and a template copy-ctor exist
// and the templated version is made 'explicit', the explicit is also
// given to the non-templated version, making the class non-implicitely-copyable.
//
#define BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION
#endif
namespace boost {
class InPlaceFactoryBase ;
@ -65,7 +81,7 @@ namespace optional_detail {
// This local class is used instead of that in "aligned_storage.hpp"
// because I've found the 'official' class to ICE BCB5.5
// when some types are used with optional<>
// when some types are used with optional<>
// (due to sizeof() passed down as a non-type template parameter)
template <class T>
class aligned_storage
@ -105,8 +121,10 @@ struct types_when_is_ref
typedef raw_type& argument_type ;
} ;
struct optional_tag {} ;
template<class T>
class optional_base
class optional_base : public optional_tag
{
private :
@ -138,7 +156,7 @@ class optional_base
// Creates an optional<T> uninitialized.
// No-throw
optional_base ()
optional_base()
:
m_initialized(false) {}
@ -168,7 +186,7 @@ class optional_base
}
// This is used for both converting and in-place constructions.
// Derived classes use the 'tag' to select the appropriate
// Derived classes use the 'tag' to select the appropriate
// implementation (the correct 'construct()' overload)
template<class Expr>
explicit optional_base ( Expr const& expr, Expr const* tag )
@ -177,74 +195,36 @@ class optional_base
{
construct(expr,tag);
}
// No-throw (assuming T::~T() doesn't)
~optional_base() { destroy() ; }
// Assigns from another optional<T> (deep-copies the rhs value)
// Basic Guarantee: If T::T( T const& ) throws, this is left UNINITIALIZED
optional_base& operator= ( optional_base const& rhs )
{
destroy(); // no-throw
if ( rhs.is_initialized() )
{
// An exception can be thrown here.
// If it happens, THIS will be left uninitialized.
construct(rhs.get_impl());
}
return *this ;
}
void assign ( optional_base const& rhs ) { assign_impl(rhs,is_reference_predicate()); }
// Assigns from a T (deep-copies the rhs value)
// Basic Guarantee: If T::( T const& ) throws, this is left UNINITIALIZED
optional_base& operator= ( argument_type val )
{
destroy(); // no-throw
// An exception can be thrown here.
// If it happens, THIS will be left uninitialized.
construct(val);
return *this ;
}
void assign ( argument_type val ) { assign_impl(val,is_reference_predicate()); }
// Assigns from "none", destroying the current value, if any, leaving this UNINITIALIZED
// No-throw (assuming T::~T() doesn't)
optional_base& operator= ( detail::none_t const& )
{
reset();
return *this ;
}
void assign ( detail::none_t const& ) { destroy(); }
#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
template<class Expr>
void assign_expr ( Expr const& expr, Expr const* tag )
{
destroy(); // no-throw
// An exception can be thrown here.
// If it happens, THIS will be left uninitialized.
construct(expr,tag);
}
void assign_expr ( Expr const& expr, Expr const* tag ) { assign_expr_impl(expr,tag,is_reference_predicate()) ; }
#endif
public :
// Destroys the current value, if any, leaving this UNINITIALIZED
// No-throw (assuming T::~T() doesn't)
void reset()
{
destroy();
}
void reset() { destroy(); }
// Replaces the current value -if any- with 'val'
// Basic Guarantee: If T::T( T const& ) throws this is left UNINITIALIZED.
void reset ( argument_type val )
{
destroy();
construct(val);
}
void reset ( argument_type val ) { assign_impl(val,is_reference_predicate()); }
// Returns a pointer to the value if this is initialized, otherwise,
// returns NULL.
@ -253,7 +233,7 @@ class optional_base
pointer_type get_ptr() { return m_initialized ? get_ptr_impl() : 0 ; }
bool is_initialized() const { return m_initialized ; }
protected :
void construct ( argument_type val )
@ -261,7 +241,7 @@ class optional_base
new (m_storage.address()) internal_type(val) ;
m_initialized = true ;
}
#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
// Constructs in-place using the given factory
template<class Expr>
@ -281,11 +261,11 @@ class optional_base
m_initialized = true ;
}
#endif
// Constructs using any expression implicitely convertible to the single argument
// of a one-argument T constructor.
// 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.
// '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* )
{
@ -293,14 +273,125 @@ class optional_base
m_initialized = true ;
}
void destroy()
{
if ( m_initialized )
destroy_impl(is_reference_predicate()) ;
}
template<class Expr>
void assign_expr_to_ref ( Expr const& expr, void const* )
{
get_impl() = expr ;
m_initialized = true ;
}
#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
//
// Notice that 'Expr' will be optional<T> or optional<U> (but not 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.
new (m_storage.address()) internal_type(expr.get()) ;
m_initialized = true ;
}
}
template<class Expr>
void assign_expr_to_ref ( Expr const& expr, optional_tag const* )
{
if ( expr.is_initialized() )
{
// An exception can be thrown here.
// It it happens, THIS will be left uninitialized.
get_impl() = expr.get() ;
m_initialized = true ;
}
}
#endif
void assign_impl ( optional_base const& rhs, is_not_reference_tag tag )
{
destroy();
if ( rhs.is_initialized() )
construct(rhs.get_impl());
}
void assign_impl ( optional_base const& rhs, is_reference_tag )
{
if ( is_initialized() )
{
destroy();
if ( rhs.is_initialized() )
assign_to_referenced(rhs.get_impl());
}
else
{
if ( rhs.is_initialized() )
construct(rhs.get_impl());
}
}
void assign_impl ( argument_type val, is_not_reference_tag )
{
destroy();
construct(val);
}
void assign_impl ( argument_type val, is_reference_tag )
{
if ( is_initialized() )
{
destroy();
assign_to_referenced(val);
}
else
construct(val);
}
#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
template<class Expr>
void assign_expr_impl ( Expr const& expr, Expr const* expr_tag, is_not_reference_tag )
{
destroy();
construct(expr,expr_tag);
}
template<class Expr>
void assign_expr_impl ( Expr const& expr, Expr const* expr_tag, is_reference_tag )
{
if ( is_initialized() )
{
destroy();
assign_expr_to_ref(expr,expr_tag);
}
else
construct(expr,expr_tag);
}
#endif
void assign_to_referenced ( argument_type val )
{
get_impl() = val ;
m_initialized = true ;
}
void destroy()
{
if ( m_initialized )
destroy_impl(is_reference_predicate()) ;
}
unspecified_bool_type safe_bool() const { return m_initialized ? &this_type::is_initialized : 0 ; }
reference_const_type get_impl() const { return dereference(get_object(), is_reference_predicate() ) ; }
reference_type get_impl() { return dereference(get_object(), is_reference_predicate() ) ; }
@ -319,7 +410,6 @@ class optional_base
reference_const_type dereference( internal_type const* p, is_reference_tag ) const { return p->get() ; }
reference_type dereference( internal_type* p, is_reference_tag ) { return p->get() ; }
// BCC564 complains about get_object()->~internal_type(), so the following dispatch is neccesary.
void destroy_impl ( is_not_reference_tag ) { get_impl().~T() ; m_initialized = false ; }
void destroy_impl ( is_reference_tag ) { m_initialized = false ; }
@ -378,16 +468,18 @@ class optional : public optional_detail::optional_base<T>
base()
{
if ( rhs.is_initialized() )
construct(rhs.get());
this->construct(rhs.get());
}
#endif
#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
// Creates an optional<T> with an expression which can be either
// (a) An instance of InPlaceFactory (i.e. in_place(a,b,...,n);
// (b) An instance of TypedInPlaceFactory ( i.e. in_place<T>(a,b,...,n);
// (c) Any expression implicitely convertible to the single type
// of a one-argument T's constructor.
// (d*) Weak compilers (BCB) might also resolved Expr as optional<T> and optional<U>
// even though explicit overloads are present for these.
// Depending on the above some T ctor is called.
// Can throw is the resolved T ctor throws.
template<class Expr>
@ -401,28 +493,42 @@ class optional : public optional_detail::optional_base<T>
// No-throw (assuming T::~T() doesn't)
~optional() {}
#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
// Assigns from an expression. See corresponding constructor.
// Basic Guarantee: If the resolved T ctor throws, this is left UNINITIALIZED
template<class Expr>
optional& operator= ( Expr expr )
{
this->assign_expr(expr,&expr);
return *this ;
}
#endif
#ifndef BOOST_OPTIONAL_NO_CONVERTING_ASSIGNMENT
// Assigns from another convertible optional<U> (converts && deep-copies the rhs value)
// Requires a valid conversion from U to T.
// Basic Guarantee: If T::T( U const& ) throws, this is left UNINITIALIZED
template<class U>
optional& operator= ( optional<U> const& rhs )
{
destroy(); // no-throw
this->destroy(); // no-throw
if ( rhs.is_initialized() )
{
// An exception can be thrown here.
// It it happens, THIS will be left uninitialized.
construct(rhs.get());
this->assign_val(rhs.get());
}
return *this ;
}
#endif
// 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)
optional& operator= ( optional const& rhs )
{
this->base::operator= ( rhs ) ;
this->assign( rhs ) ;
return *this ;
}
@ -430,7 +536,7 @@ class optional : public optional_detail::optional_base<T>
// Basic Guarantee: If T::( T const& ) throws, this is left UNINITIALIZED
optional& operator= ( argument_type val )
{
this->base::operator= ( val ) ;
this->assign( val ) ;
return *this ;
}
@ -439,27 +545,16 @@ class optional : public optional_detail::optional_base<T>
// No-throw (assuming T::~T() doesn't)
optional& operator= ( detail::none_t const& none_ )
{
this->base::operator= ( none_ ) ;
this->assign( none_ ) ;
return *this ;
}
#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
// Assigns from an expression. See corresponding constructor.
// Basic Guarantee: If the resolved T ctor throws, this is left UNINITIALIZED
template<class Expr>
optional& operator= ( Expr expr )
{
this->base::assign_expr(expr,&expr);
return *this ;
}
#endif
// Returns a reference to the value if this is initialized, otherwise,
// the behaviour is UNDEFINED
// No-throw
reference_const_type get() const { BOOST_ASSERT(this->is_initialized()) ; return this->get_impl(); }
reference_type get() { BOOST_ASSERT(this->is_initialized()) ; return this->get_impl(); }
// Returns a pointer to the value if this is initialized, otherwise,
// the behaviour is UNDEFINED
// No-throw