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I started a weird rewrite, but I'll likely abandon it.

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But I'll keep this commit in my history, in case I want to try again.
This commit is contained in:
ADAM David Alan Martin
2023-10-31 01:44:34 -04:00
parent 3a5f6367b9
commit 4a74921cb8
2 changed files with 97 additions and 51 deletions
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46
IOStreams/StreamState.h
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@ -15,43 +15,42 @@ namespace Alepha::Hydrogen::IOStreams ::detail:: stream_state
class StreamState;
}
template< typename Tag, typename Type, auto Default >
class exports::StreamState
template< typename Type >
class exports::StreamState : boost::noncopyable
{
private:
static auto
index()
{
static const auto rv= std::ios::xalloc();
return rv;
}
const int index= std::ios::xalloc();
static Type *&
get_ptr( std::ios_base &ios, const int idx )
{
return reinterpret_cast< Type *& >( ios.pword( idx ) );
}
Type *&
get_ptr( std::ios_base &ios )
{
return reinterpret_cast< Type *& >( ios.pword( index() ) );
get_ptr( ios, index );
}
static void
destroy( std::ios_base &ios )
destroy( std::ios_base &ios, const int idx )
{
delete get_ptr( ios );
get_ptr( ios )= nullptr;
delete get_ptr( ios, idx );
get_ptr( ios, idx )= nullptr;
}
static void
callback_impl( const std::ios_base::event event, std::ios_base &ios, const int idx )
{
if( idx != index() ) throw std::logic_error( "Wrong index." );
if( event == std::ios_base::erase_event ) destroy( ios );
if( event == std::ios_base::erase_event ) destroy( ios, idx );
else if( event == std::ios_base::imbue_event )
{
// Nothing to do... until I develop locale support.
}
else if( event == std::ios_base::copyfmt_event )
{
get_ptr( ios )= new Type{ get( ios ) };
get_ptr( ios, idx )= new Type{ get( ios, idx ) };
}
}
@ -61,20 +60,20 @@ namespace Alepha::Hydrogen::IOStreams ::detail:: stream_state
return callback_impl( event, ios, idx );
}
static void
void
init( std::ios_base &ios )
{
if( not ios.iword( index() ) )
if( not ios.iword( idx ) )
{
ios.iword( index() )= 1;
ios.register_callback( callback, index() );
ios.register_callback( callback, idx );
}
auto *&ptr= get_ptr( ios );
auto *&ptr= get_ptr( ios, idx );
if( not ptr ) ptr= new Type{ Default() };
}
public:
static Type &
Type &
get( std::ios_base &ios )
{
init( ios );
@ -83,19 +82,20 @@ namespace Alepha::Hydrogen::IOStreams ::detail:: stream_state
struct Setter
{
StreamState *state;
const Type val;
friend std::ostream &
operator << ( std::ostream &os, const Setter &s )
{
StreamState::get( os )= s.val;
s.get( os )= s.val;
return os;
}
friend std::istream &
operator >> ( std::istream &is, const Setter &s )
{
StreamState::get( is )= s.val;
s.get( is )= s.val;
return is;
}
};