apache::subversion::svnxx::tristate Class Reference

A three-state Boolean-like type. More...

#include <svnxx/tristate.hpp>

Public Member Functions
constexpr	tristate (bool initial_value) noexcept
	Constructor for the true and false states.
constexpr	operator safe_bool () const noexcept
	Safe conversion to bool. More...
constexpr tristate	operator! () const noexcept
	Logical negation. More...
constexpr	tristate (boost::tribool t) noexcept
	Conversion from boost::tribool. More...
constexpr	operator boost::tribool () const noexcept
	Conversion to boost::tribool. More...

Static Public Member Functions
static constexpr tristate	unknown () noexcept
	Factory method for the unknown state.

Related Functions
(Note that these are not member functions.)
constexpr bool	unknown (tristate t) noexcept
	Test for the unknown tristate state. More...
constexpr tristate	operator&& (tristate t, tristate u) noexcept
	Logical conjunction. More...
constexpr tristate	operator&& (tristate t, bool b) noexcept
constexpr tristate	operator&& (bool b, tristate t) noexcept
constexpr tristate	operator&& (tristate t, boost::tribool b) noexcept
constexpr tristate	operator&& (boost::tribool b, tristate t) noexcept
constexpr tristate	operator|| (tristate t, tristate u) noexcept
	Logical disjunction. More...
constexpr tristate	operator|| (tristate t, bool b) noexcept
constexpr tristate	operator|| (bool b, tristate t) noexcept
constexpr tristate	operator|| (tristate t, boost::tribool b) noexcept
constexpr tristate	operator|| (boost::tribool b, tristate t) noexcept
constexpr tristate	operator== (tristate t, tristate u) noexcept
	Equality comparison. More...
constexpr tristate	operator== (tristate t, bool b) noexcept
constexpr tristate	operator== (bool b, tristate t) noexcept
constexpr tristate	operator== (tristate t, boost::tribool b) noexcept
constexpr tristate	operator== (boost::tribool b, tristate t) noexcept
constexpr tristate	operator!= (tristate t, tristate u) noexcept
	Inquality comparison. More...
constexpr tristate	operator!= (tristate t, bool b) noexcept
constexpr tristate	operator!= (bool b, tristate t) noexcept
constexpr tristate	operator!= (tristate t, boost::tribool b) noexcept
constexpr tristate	operator!= (boost::tribool b, tristate t) noexcept

Detailed Description

A three-state Boolean-like type.

tristate values represent one of three states:

• the true state (equivalent to Boolean true);
• the false state (equivalent to Boolean false);
• the unknown state.

tristate constructors, methods and operators are all compile-time constant expressions and can be used to initialize other constexpr values. And unlike most other types, comparisons and logical operations between tristate values return a tristate, not a bool.

Given a tristate value t, the state it represents can be uniquely determined by the following coding pattern:

if (t) {
    // t is true
}
else if (!t) {
    // t is false
else {
    // t is unknown
}

Note

Inspired by boost::tribool

Definition at line 69 of file tristate.hpp.

Constructor & Destructor Documentation

tristate()

constexpr apache::subversion::svnxx::tristate::tristate ( boost::tribool  t )

inlineconstexprnoexcept

Conversion from boost::tribool.

Returns

a tribool value equivalent to the t.

Note

Avalible only if SVNXX_USE_BOOST is defined.

Definition at line 153 of file tristate.hpp.

Member Function Documentation

operator boost::tribool()

constexpr apache::subversion::svnxx::tristate::operator boost::tribool ( ) const

inlineconstexprnoexcept

Conversion to boost::tribool.

Returns

a boost::tribool value equivalent to the tristate value.

Note

Avalible only if SVNXX_USE_BOOST is defined.

Definition at line 164 of file tristate.hpp.

operator safe_bool()

constexpr apache::subversion::svnxx::tristate::operator safe_bool ( ) const

inlineconstexprnoexcept

Safe conversion to bool.

Returns

a true-like value only when this tristate is the true state.

Definition at line 103 of file tristate.hpp.

operator!()

constexpr tristate apache::subversion::svnxx::tristate::operator! ( ) const

inlineconstexprnoexcept

Logical negation.

Returns

the logical negation of a tristate, according to the following table:

!
false	true
true	false
unknown	unknown

Definition at line 131 of file tristate.hpp.

References unknown().

Friends And Related Function Documentation

operator!=() [1/5]

constexpr tristate operator!= ( bool  b, tristate  t  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 470 of file tristate.hpp.

operator!=() [2/5]

constexpr tristate operator!= ( boost::tribool  b, tristate  t  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Note

Avalible only if SVNXX_USE_BOOST is defined.

Definition at line 491 of file tristate.hpp.

operator!=() [3/5]

constexpr tristate operator!= ( tristate  t, bool  b  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 461 of file tristate.hpp.

operator!=() [4/5]

constexpr tristate operator!= ( tristate  t, boost::tribool  b  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Note

Avalible only if SVNXX_USE_BOOST is defined.

Definition at line 481 of file tristate.hpp.

operator!=() [5/5]

constexpr tristate operator!= ( tristate  t, tristate  u  )

related

Inquality comparison.

Returns

the result of comparing two tristate values for inequality, according to the following table:

!=	false	true	unknown
false	false	true	unknown
true	true	false	unknown
unknown	unknown	unknown	unknown

Definition at line 451 of file tristate.hpp.

References unknown().

operator&&() [1/5]

constexpr tristate operator&& ( bool  b, tristate  t  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 235 of file tristate.hpp.

operator&&() [2/5]

constexpr tristate operator&& ( boost::tribool  b, tristate  t  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Note

Avalible only if SVNXX_USE_BOOST is defined.

Definition at line 256 of file tristate.hpp.

operator&&() [3/5]

constexpr tristate operator&& ( tristate  t, bool  b  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 226 of file tristate.hpp.

operator&&() [4/5]

constexpr tristate operator&& ( tristate  t, boost::tribool  b  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Note

Avalible only if SVNXX_USE_BOOST is defined.

Definition at line 246 of file tristate.hpp.

operator&&() [5/5]

constexpr tristate operator&& ( tristate  t, tristate  u  )

related

Logical conjunction.

Returns

the result of a logical AND of two tristate values, according to the following table:

&&	false	true	unknown
false	false	false	false
true	false	true	unknown
unknown	false	unknown	unknown

Definition at line 215 of file tristate.hpp.

References unknown().

operator==() [1/5]

constexpr tristate operator== ( bool  b, tristate  t  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 392 of file tristate.hpp.

operator==() [2/5]

constexpr tristate operator== ( boost::tribool  b, tristate  t  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Note

Avalible only if SVNXX_USE_BOOST is defined.

Definition at line 413 of file tristate.hpp.

operator==() [3/5]

constexpr tristate operator== ( tristate  t, bool  b  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 383 of file tristate.hpp.

operator==() [4/5]

constexpr tristate operator== ( tristate  t, boost::tribool  b  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Note

Avalible only if SVNXX_USE_BOOST is defined.

Definition at line 403 of file tristate.hpp.

operator==() [5/5]

constexpr tristate operator== ( tristate  t, tristate  u  )

related

Equality comparison.

Returns

the result of comparing two tristate values for equality, according to the following table:

==	false	true	unknown
false	true	false	unknown
true	false	true	unknown
unknown	unknown	unknown	unknown

Definition at line 373 of file tristate.hpp.

References unknown().

operator||() [1/5]

constexpr tristate operator|| ( bool  b, tristate  t  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 314 of file tristate.hpp.

operator||() [2/5]

constexpr tristate operator|| ( boost::tribool  b, tristate  t  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Note

Avalible only if SVNXX_USE_BOOST is defined.

Definition at line 335 of file tristate.hpp.

operator||() [3/5]

constexpr tristate operator|| ( tristate  t, bool  b  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 305 of file tristate.hpp.

operator||() [4/5]

constexpr tristate operator|| ( tristate  t, boost::tribool  b  )

related

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Note

Avalible only if SVNXX_USE_BOOST is defined.

Definition at line 325 of file tristate.hpp.

operator||() [5/5]

constexpr tristate operator|| ( tristate  t, tristate  u  )

related

Logical disjunction.

Returns

the result of a logical OR of two tristate values, according to the following table:

||	false	true	unknown
false	false	true	unknown
true	true	true	true
unknown	unknown	true	unknown

Definition at line 294 of file tristate.hpp.

References unknown().

unknown()

constexpr bool unknown ( tristate  t )

related

Test for the unknown tristate state.

Returns

true only if t is the unknown state.

Definition at line 178 of file tristate.hpp.

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

• svnxx/tristate.hpp