Scine::Molassembler::Temple::Optional< T > Class Template Reference

An Option monadic type. More...

#include <Optional.h>

Public Member Functions
Constructors
constexpr	Optional ()
	Default constructor. More...
constexpr	Optional (T value)
	Value constructor.
Information
PURITY_WEAK constexpr bool	hasValue () const
	Returns whether the optional contains a value. More...
PURITY_WEAK constexpr T	value () const
	Returns the contained value unchecked. More...
template<class UnaryFunction >
constexpr auto	map (UnaryFunction &&function) const
	Monadic bind with function of signature T -> U. More...
template<class UnaryFunction >
constexpr auto	flatMap (UnaryFunction &&function) const
	Monadic bind with function of signature T -> Optional<U> More...
PURITY_WEAK constexpr T	valueOr (const T &alternative) const
	Returns a value if initialized, and another if not. More...
Operators
constexpr Optional &	operator= (T assignment)
	Assignment from T.
PURITY_WEAK constexpr	operator bool () const
	Convert-to-bool operator.
PURITY_WEAK constexpr bool	operator== (const Optional &other) const
	Compares on basis of contained value. Nones do compare equal.
PURITY_WEAK constexpr bool	operator!= (const Optional &other) const
	Compares on basis of contained value. Nones do compare equal.
PURITY_WEAK constexpr bool	operator< (const Optional &other) const
	Lexicographical-like comparison.
PURITY_WEAK constexpr bool	operator> (const Optional &other) const
	Lexicographical-like comparison.

Private Attributes
T	value_ = T {}
bool	hasValue_ = false

Detailed Description

template<typename T>
class Scine::Molassembler::Temple::Optional< T >

An Option monadic type.

A constexpr option type much like std::optional with the limitation that T must be:

• DefaultConstructible
• LessThanComparable
• EqualityComparable

(see the C++ standard definitions)

Warning

T may not be a reference or const-qualified type. Those are impossible to implement constexpr in C++14 as far as I can tell.

Constructor & Destructor Documentation

template<typename T >

constexpr Scine::Molassembler::Temple::Optional< T >::Optional ( )

inline

Default constructor.

None value. Default constructs a contained type.

Member Function Documentation

template<typename T >

template<class UnaryFunction >

constexpr auto Scine::Molassembler::Temple::Optional< T >::flatMap ( UnaryFunction &&  function ) const

inline

Monadic bind with function of signature T -> Optional<U>

Template Parameters

UnaryFunction,:

Function of signature T -> Optional<U>

Returns

Optional<U>

template<typename T >

PURITY_WEAK constexpr bool Scine::Molassembler::Temple::Optional< T >::hasValue ( ) const

inline

Returns whether the optional contains a value.

Complexity \(\Theta(1)\)

template<typename T >

template<class UnaryFunction >

constexpr auto Scine::Molassembler::Temple::Optional< T >::map ( UnaryFunction &&  function ) const

inline

Monadic bind with function of signature T -> U.

Template Parameters

UnaryFunction,:

Function of signature T -> U

Returns

Optional<U>

template<typename T >

PURITY_WEAK constexpr T Scine::Molassembler::Temple::Optional< T >::value ( ) const

inline

Returns the contained value unchecked.

Complexity \(\Theta(1)\)

Warning

If hasValue is false, this is UB.

template<typename T >

PURITY_WEAK constexpr T Scine::Molassembler::Temple::Optional< T >::valueOr ( const T &  alternative ) const

inline

Returns a value if initialized, and another if not.

Complexity \(\Theta(1)\)

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The documentation for this class was generated from the following file:

• Molassembler/Temple/constexpr/Optional.h