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# pragma once
# include "CoreTypes.h"
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# include "Templates/Utility.h"
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# include "Templates/TypeHash.h"
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# include "TypeTraits/TypeTraits.h"
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# include "Miscellaneous/Compare.h"
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# include "Miscellaneous/AssertionMacros.h"
NAMESPACE_REDCRAFT_BEGIN
NAMESPACE_MODULE_BEGIN ( Redcraft )
NAMESPACE_MODULE_BEGIN ( Utility )
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template < typename OptionalType > requires ( CDestructible < OptionalType > )
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class TOptional
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{
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private :
template < typename T >
struct TAllowUnwrapping : TBoolConstant < ! (
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CConstructibleFrom < OptionalType , TOptional < T > & >
| | CConstructibleFrom < OptionalType , const TOptional < T > & >
| | CConstructibleFrom < OptionalType , TOptional < T > & & >
| | CConstructibleFrom < OptionalType , const TOptional < T > & & >
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| | CConvertibleTo < TOptional < T > & , OptionalType >
| | CConvertibleTo < const TOptional < T > & , OptionalType >
| | CConvertibleTo < TOptional < T > & & , OptionalType >
| | CConvertibleTo < const TOptional < T > & & , OptionalType >
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| | CAssignableFrom < OptionalType & , TOptional < T > & >
| | CAssignableFrom < OptionalType & , const TOptional < T > & >
| | CAssignableFrom < OptionalType & , TOptional < T > & & >
| | CAssignableFrom < OptionalType & , const TOptional < T > & & >
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) > { } ;
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public :
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using ValueType = OptionalType ;
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constexpr TOptional ( ) : bIsValid ( false ) { }
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constexpr TOptional ( FInvalid ) : TOptional ( ) { }
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template < typename . . . Ts > requires ( CConstructibleFrom < OptionalType , Ts . . . > )
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constexpr explicit TOptional ( FInPlace , Ts & & . . . Args )
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: bIsValid ( true )
{
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new ( & Value ) OptionalType ( Forward < Ts > ( Args ) . . . ) ;
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}
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template < typename T = OptionalType > requires ( CConstructibleFrom < OptionalType , T & & > )
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& & ( ! CSameAs < TRemoveCVRef < T > , FInPlace > ) & & ( ! CBaseOf < TOptional , TRemoveCVRef < T > > )
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constexpr explicit ( ! CConvertibleTo < T & & , OptionalType > ) TOptional ( T & & InValue )
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: TOptional ( InPlace , Forward < T > ( InValue ) )
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{ }
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constexpr TOptional ( const TOptional & InValue ) requires ( CTriviallyCopyConstructible < OptionalType > ) = default ;
constexpr TOptional ( const TOptional & InValue ) requires ( CCopyConstructible < OptionalType > & & ! CTriviallyCopyConstructible < OptionalType > )
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: bIsValid ( InValue . IsValid ( ) )
{
if ( InValue . IsValid ( ) ) new ( & Value ) OptionalType ( InValue . GetValue ( ) ) ;
}
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constexpr TOptional ( TOptional & & InValue ) requires ( CTriviallyMoveConstructible < OptionalType > ) = default ;
constexpr TOptional ( TOptional & & InValue ) requires ( CMoveConstructible < OptionalType > & & ! CTriviallyMoveConstructible < OptionalType > )
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: bIsValid ( InValue . IsValid ( ) )
{
if ( InValue . IsValid ( ) ) new ( & Value ) OptionalType ( MoveTemp ( InValue . GetValue ( ) ) ) ;
}
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template < typename T = OptionalType > requires ( CConstructibleFrom < OptionalType , const T & > & & TAllowUnwrapping < T > : : Value )
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constexpr explicit ( ! CConvertibleTo < const T & , OptionalType > ) TOptional ( const TOptional < T > & InValue )
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: bIsValid ( InValue . IsValid ( ) )
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{
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if ( InValue . IsValid ( ) ) new ( & Value ) OptionalType ( InValue . GetValue ( ) ) ;
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}
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template < typename T = OptionalType > requires ( CConstructibleFrom < OptionalType , T & & > & & TAllowUnwrapping < T > : : Value )
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constexpr explicit ( ! CConvertibleTo < T & & , OptionalType > ) TOptional ( TOptional < T > & & InValue )
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: bIsValid ( InValue . IsValid ( ) )
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{
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if ( InValue . IsValid ( ) ) new ( & Value ) OptionalType ( MoveTemp ( InValue . GetValue ( ) ) ) ;
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}
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constexpr ~ TOptional ( ) requires ( CTriviallyDestructible < OptionalType > ) = default ;
constexpr ~ TOptional ( ) requires ( ! CTriviallyDestructible < OptionalType > )
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{
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Reset ( ) ;
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}
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constexpr TOptional & operator = ( const TOptional & InValue ) requires ( CTriviallyCopyConstructible < OptionalType > & & CTriviallyCopyAssignable < OptionalType > ) = default ;
constexpr TOptional & operator = ( const TOptional & InValue ) requires ( CCopyConstructible < OptionalType > & & CCopyAssignable < OptionalType >
& & ! CTriviallyCopyConstructible < OptionalType > & & ! CTriviallyCopyAssignable < OptionalType > )
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{
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if ( & InValue = = this ) return * this ;
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if ( ! InValue . IsValid ( ) )
{
Reset ( ) ;
return * this ;
}
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if ( IsValid ( ) ) GetValue ( ) = InValue . GetValue ( ) ;
else
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{
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new ( & Value ) OptionalType ( InValue . GetValue ( ) ) ;
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bIsValid = true ;
}
return * this ;
}
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constexpr TOptional & operator = ( TOptional & & InValue ) requires ( CTriviallyMoveConstructible < OptionalType > & & CTriviallyMoveAssignable < OptionalType > ) = default ;
constexpr TOptional & operator = ( TOptional & & InValue ) requires ( CMoveConstructible < OptionalType > & & CMoveAssignable < OptionalType >
& & ! CTriviallyMoveConstructible < OptionalType > & & ! CTriviallyMoveAssignable < OptionalType > )
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{
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if ( & InValue = = this ) return * this ;
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if ( ! InValue . IsValid ( ) )
{
Reset ( ) ;
return * this ;
}
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if ( IsValid ( ) ) GetValue ( ) = MoveTemp ( InValue . GetValue ( ) ) ;
else
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{
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new ( & Value ) OptionalType ( MoveTemp ( InValue . GetValue ( ) ) ) ;
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bIsValid = true ;
}
return * this ;
}
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template < typename T = OptionalType > requires ( CConstructibleFrom < OptionalType , const T & >
& & CAssignableFrom < OptionalType & , const T & > & & TAllowUnwrapping < T > : : Value )
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constexpr TOptional & operator = ( const TOptional < T > & InValue )
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{
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if ( ! InValue . IsValid ( ) )
{
Reset ( ) ;
return * this ;
}
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if ( IsValid ( ) ) GetValue ( ) = InValue . GetValue ( ) ;
else
{
new ( & Value ) OptionalType ( InValue . GetValue ( ) ) ;
bIsValid = true ;
}
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return * this ;
}
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template < typename T = OptionalType > requires ( CConstructibleFrom < OptionalType , T & & >
& & CAssignableFrom < OptionalType & , T & & > & & TAllowUnwrapping < T > : : Value )
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constexpr TOptional & operator = ( TOptional < T > & & InValue )
{
if ( ! InValue . IsValid ( ) )
{
Reset ( ) ;
return * this ;
}
if ( IsValid ( ) ) GetValue ( ) = MoveTemp ( InValue . GetValue ( ) ) ;
else
{
new ( & Value ) OptionalType ( MoveTemp ( InValue . GetValue ( ) ) ) ;
bIsValid = true ;
}
return * this ;
}
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template < typename T = OptionalType > requires ( CConstructibleFrom < OptionalType , T & & > & & CAssignableFrom < OptionalType & , T & & > )
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constexpr TOptional & operator = ( T & & InValue )
{
if ( IsValid ( ) ) GetValue ( ) = Forward < T > ( InValue ) ;
else
{
new ( & Value ) OptionalType ( Forward < T > ( InValue ) ) ;
bIsValid = true ;
}
return * this ;
}
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template < typename . . . ArgTypes > requires ( CConstructibleFrom < OptionalType , ArgTypes . . . > )
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constexpr OptionalType & Emplace ( ArgTypes & & . . . Args )
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{
Reset ( ) ;
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OptionalType * Result = new ( & Value ) OptionalType ( Forward < ArgTypes > ( Args ) . . . ) ;
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bIsValid = true ;
return * Result ;
}
constexpr bool IsValid ( ) const { return bIsValid ; }
constexpr explicit operator bool ( ) const { return bIsValid ; }
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constexpr OptionalType & GetValue ( ) & { checkf ( IsValid ( ) , TEXT ( " It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead. " ) ) ; return * reinterpret_cast < OptionalType * > ( & Value ) ; }
constexpr OptionalType & & GetValue ( ) & & { checkf ( IsValid ( ) , TEXT ( " It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead. " ) ) ; return MoveTemp ( * reinterpret_cast < OptionalType * > ( & Value ) ) ; }
constexpr const OptionalType & GetValue ( ) const & { checkf ( IsValid ( ) , TEXT ( " It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead. " ) ) ; return * reinterpret_cast < const OptionalType * > ( & Value ) ; }
constexpr const OptionalType & & GetValue ( ) const & & { checkf ( IsValid ( ) , TEXT ( " It is an error to call GetValue() on an unset TOptional. Please either check IsValid() or use Get(DefaultValue) instead. " ) ) ; return MoveTemp ( * reinterpret_cast < const OptionalType * > ( & Value ) ) ; }
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constexpr const OptionalType * operator - > ( ) const { return & GetValue ( ) ; }
constexpr OptionalType * operator - > ( ) { return & GetValue ( ) ; }
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constexpr OptionalType & operator * ( ) & { return GetValue ( ) ; }
constexpr OptionalType & & operator * ( ) & & { return GetValue ( ) ; }
constexpr const OptionalType & operator * ( ) const & { return GetValue ( ) ; }
constexpr const OptionalType & & operator * ( ) const & & { return GetValue ( ) ; }
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constexpr OptionalType & Get ( OptionalType & DefaultValue ) & { return IsValid ( ) ? GetValue ( ) : DefaultValue ; }
constexpr const OptionalType & Get ( const OptionalType & DefaultValue ) const & { return IsValid ( ) ? GetValue ( ) : DefaultValue ; }
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constexpr void Reset ( )
{
if ( bIsValid )
{
bIsValid = false ;
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typedef OptionalType DestructOptionalType ;
( ( OptionalType * ) & Value ) - > DestructOptionalType : : ~ DestructOptionalType ( ) ;
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}
}
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constexpr size_t GetTypeHash ( ) const requires ( CHashable < OptionalType > )
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{
if ( ! IsValid ( ) ) return 2824517378 ;
return NAMESPACE_REDCRAFT : : GetTypeHash ( GetValue ( ) ) ;
}
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template < typename T > requires ( CMoveConstructible < OptionalType > & & CSwappable < OptionalType > )
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constexpr void Swap ( TOptional & InValue )
{
if ( ! IsValid ( ) & & ! InValue . IsValid ( ) ) return ;
if ( IsValid ( ) & & ! InValue . IsValid ( ) )
{
InValue = MoveTemp ( * this ) ;
Reset ( ) ;
return ;
}
if ( InValue . IsValid ( ) & & ! IsValid ( ) )
{
* this = MoveTemp ( InValue ) ;
InValue . Reset ( ) ;
return ;
}
NAMESPACE_REDCRAFT : : Swap ( GetValue ( ) , InValue . GetValue ( ) ) ;
}
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private :
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TAlignedStorage < sizeof ( OptionalType ) , alignof ( OptionalType ) > Value ;
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bool bIsValid ;
} ;
template < typename T >
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TOptional ( T ) - > TOptional < T > ;
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template < typename T , typename U > requires ( CWeaklyEqualityComparable < T , U > )
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constexpr bool operator = = ( const TOptional < T > & LHS , const TOptional < U > & RHS )
{
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if ( LHS . IsValid ( ) ! = RHS . IsValid ( ) ) return false ;
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if ( LHS . IsValid ( ) = = false ) return true ;
return * LHS = = * RHS ;
}
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template < typename T , typename U > requires ( CSynthThreeWayComparable < T , U > )
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constexpr partial_ordering operator < = > ( const TOptional < T > & LHS , const TOptional < U > & RHS )
{
if ( LHS . IsValid ( ) ! = RHS . IsValid ( ) ) return partial_ordering : : unordered ;
if ( LHS . IsValid ( ) = = false ) return partial_ordering : : equivalent ;
return SynthThreeWayCompare ( * LHS , * RHS ) ;
}
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template < typename T , typename U > requires ( CWeaklyEqualityComparable < T , U > )
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constexpr bool operator = = ( const TOptional < T > & LHS , const U & RHS )
{
return LHS . IsValid ( ) ? * LHS = = RHS : false ;
}
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template < typename T >
constexpr bool operator = = ( const TOptional < T > & LHS , FInvalid )
{
return ! LHS . IsValid ( ) ;
}
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template < typename T > requires ( CDestructible < T > )
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constexpr TOptional < TDecay < T > > MakeOptional ( FInvalid )
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{
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return TOptional < TDecay < T > > ( Invalid ) ;
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}
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template < typename T > requires ( CDestructible < T > & & CConstructibleFrom < T , T & & > )
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constexpr TOptional < T > MakeOptional ( T & & InValue )
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{
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return TOptional < T > ( Forward < T > ( InValue ) ) ;
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}
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template < typename T , typename . . . Ts > requires ( CDestructible < T > & & CConstructibleFrom < T , Ts . . . > )
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constexpr TOptional < T > MakeOptional ( Ts & & . . . Args )
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{
return TOptional < T > ( InPlace , Forward < T > ( Args ) . . . ) ;
}
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NAMESPACE_PRIVATE_BEGIN
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template < typename T > struct TIsTOptional : FFalse { } ;
template < typename T > struct TIsTOptional < TOptional < T > > : FTrue { } ;
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NAMESPACE_PRIVATE_END
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template < typename T > concept CTOptional = NAMESPACE_PRIVATE : : TIsTOptional < TRemoveCV < T > > : : Value ;
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NAMESPACE_MODULE_END ( Utility )
NAMESPACE_MODULE_END ( Redcraft )
NAMESPACE_REDCRAFT_END