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clean up fc::optional

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This commit is contained in:
Daniel Larimer 2013-07-02 14:59:05 -04:00
parent ad3e5b1337
commit 5226987305
1 changed files with 61 additions and 37 deletions
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98
include/fc/optional.hpp
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@ -1,84 +1,88 @@
#pragma once
#include <fc/utility.hpp>
#include <assert.h>
namespace fc {
#ifdef _MSC_VER
# pragma warning(push)
# pragma warning(disable:4521) /* multiple copy ctors */
#endif
/**
* @brief provides stack-based nullable value similar to boost::optional
*
* Simply including boost::optional adds 35,000 lines to each object file, using
* fc::optional adds less than 400.
*/
#ifdef _MSC_VER
# pragma warning(push)
# pragma warning(disable:4521) /* multiple copy ctors */
#endif
template<typename T>
class optional {
class optional
{
public:
optional():_valid(0){}
~optional(){ if( _valid ) (**this).~T(); }
optional():_valid(false){}
~optional(){ reset(); }
optional( const optional& o )
:_valid(false) {
if( o._valid ) new (&**this) T( *o );
:_valid(false)
{
if( o._valid ) new (ptr()) T( *o );
_valid = o._valid;
}
optional( optional& o )
:_valid(false) {
if( o._valid ) new (&**this) T( *o );
:_valid(false)
{
if( o._valid ) new (ptr()) T( *o );
_valid = o._valid;
}
optional( optional&& o )
:_valid(false) {
if( o._valid ) new (&**this) T( fc::move(*o) );
:_valid(false)
{
if( o._valid ) new (ptr()) T( fc::move(*o) );
_valid = o._valid;
o.reset();
}
template<typename U>
optional( U&& u )
:_valid(false) {
new (&**this) T( fc::forward<U>(u) );
:_valid(false)
{
new (ptr()) T( fc::forward<U>(u) );
_valid = true;
}
template<typename U>
optional& operator=( U&& u ) {
if( !_valid ) {
new (&**this) T( fc::forward<U>(u) );
_valid = true;
} else {
**this = static_cast<T>(fc::forward<U>(u));
}
optional& operator=( U&& u )
{
reset();
new (ptr()) T( fc::forward<U>(u) );
return *this;
}
optional& operator=( const optional& o ) {
if (this != &o) {
if( _valid && o._valid ) {
**this = *o;
ref() = *o;
} else if( !_valid && o._valid ) {
*this = *o;
new (ptr()) T( *o );
_valid = true;
} else if (_valid) {
(**this).~T();
_valid = false;
reset();
}
}
return *this;
}
optional& operator=( optional&& o ) {
if (this != &o) {
optional& operator=( optional&& o )
{
if (this != &o)
{
if( _valid && o._valid ) {
**this = fc::move(*o);
ref() = fc::move(*o);
} else if ( !_valid && o._valid ) {
*this = fc::move(*o);
} else if (_valid) {
(**this).~T();
_valid = false;
reset();
}
}
return *this;
@ -87,13 +91,33 @@ namespace fc {
bool operator!()const { return !_valid; }
operator bool()const { return _valid; }
T& operator*() { void* v = &_value[0]; return *static_cast<T*>(v); }
const T& operator*()const { const void* v = &_value[0]; return *static_cast<const T*>(v); }
T& operator*() { assert(_valid); return ref(); }
const T& operator*()const { assert(_valid); return ref(); }
T* operator->() { void* v = &_value[0]; return static_cast<T*>(v); }
const T* operator->()const { const void* v = &_value[0]; return static_cast<const T*>(v); }
T* operator->()
{
assert( _valid );
return ptr();
}
const T* operator->()const
{
assert( _valid );
return ptr();
}
private:
void reset()
{
if( _valid )
{
ref().~T(); // cal destructor
}
}
T& ref() { return *ptr(); }
const T& ref()const { return *ptr(); }
T* ptr() { void* v = &_value[0]; return static_cast<T*>(v); }
const T* ptr()const { const void* v = &_value[0]; return static_cast<const T*>(v); }
// force alignment... to 8 byte boundaries
double _value[8 * ((sizeof(T)+7)/8)];
bool _valid;