smats::Variable Class Reference

#include <variable.h>

Public Types
enum class	Type : std::uint8_t { CONTINUOUS , INTEGER , BINARY , BOOLEAN }
using	Id = std::size_t

Public Member Functions
	Variable ()
	Variable (const std::string &name, Type type=Type::CONTINUOUS)
	Variable (const Variable &)=default
	Variable (Variable &&other) noexcept
Variable &	operator= (const Variable &)=default
Variable &	operator= (Variable &&other) noexcept
bool	is_dummy () const
Id	id () const
Type	type () const
const std::string &	name () const
bool	equal_to (const Variable &o) const noexcept
bool	less (const Variable &o) const noexcept
void	hash (InvocableHashAlgorithm auto &hasher) const noexcept

Static Private Member Functions
static Id	get_next_id (Variable::Type type)

Private Attributes
Id	id_
	Unique identifier for the variable. The high-order byte stores the Type.
std::shared_ptr< const std::string >	name_
	Name of the variable.

Detailed Description

Represents a symbolic variable.

A symbolic variable is a named entity that can take a value from a specific domain.

Warning

Do not use the operator== to verify equality between to Variable, as it creates a Formula. Use the equal_to() method instead.

Member Enumeration Documentation

Type

enum class smats::Variable::Type : std::uint8_t

strong

Supported types of symbolic variables.

Enumerator
CONTINUOUS	A CONTINUOUS variable takes a double value.
INTEGER	An INTEGER variable takes an int value.
BINARY	A BINARY variable takes an integer value from {0, 1}.
BOOLEAN	A BOOLEAN variable takes a bool value.

Constructor & Destructor Documentation

Variable() [1/2]

smats::Variable::Variable ( )

inline

Construct a dummy variable.

All default-constructed variables are considered the same variable by the equal_to method. A moved-from variable becomes a dummy variable.

Variable() [2/2]

smats::Variable::Variable ( const std::string & name, Type type = Type::CONTINUOUS )

explicit

Constructs a variable with a string.

Parameters

name	name of the variable.
type	type of the variable.

Member Function Documentation

equal_to()

bool smats::Variable::equal_to ( const Variable & o ) const

inlinenodiscardnoexcept

Compare two variables to determine if they are equal. Two variables are equal if they have the same id_ .

Parameters

o	other object to compare against

Returns

true the two object are equal

false if the two objects are different

get_next_id()

Variable::Id smats::Variable::get_next_id ( Variable::Type type )

staticprivate

Get the next unique identifier for a variable.

The unique identifier is a 64-bit value that is composed of two parts:

• The first high-order byte stores the Type of the variable
• The remaining low-order bytes store a counter that is incremented each time a new variable is created.

Note

Id 0 is reserved for anonymous variable which is created by the default constructor, Variable(). As a result, the invariant get_next_id() > 0 is guaranteed.

Parameters

type	type of the variable

Returns

next unique identifier for a variable

hash()

void smats::Variable::hash ( InvocableHashAlgorithm auto & hasher ) const

inlinenoexcept

Compute the hash of this variable using the given hasher

Template Parameters

InvocableHashAlgorithm

type of the hash algorithm to use

Parameters

hasher

hash algorithm to use

id()

Id smats::Variable::id ( ) const

inlinenodiscard

Get read-only access to the unique identifier of the variable.

Returns

unique identifier of the variable

is_dummy()

bool smats::Variable::is_dummy ( ) const

inlinenodiscard

Check whether the  variable is a dummy variable.

A dummy variable is a variable with an ID of zero and represents an anonymous variable. It should not be used in any context other than as a placeholder.

Returns

true if the variable is a dummy variable

false if the variable is not a dummy variable

less()

bool smats::Variable::less ( const Variable & o ) const

inlinenodiscardnoexcept

Compare two variables to determine the order between them. The ordering is based on the id_ values of the two variables.

Parameters

o	other object to compare against

Returns

true if this object is less than the other object

false if this object is not less than the other object

name()

const std::string & smats::Variable::name ( ) const

nodiscard

Get read-only access to the name of the variable.

Returns

name of the variable

type()

Type smats::Variable::type ( ) const

inlinenodiscard

Get read-only access to the type of the variable. The type is stored in the upper byte of id_ .

Returns

type of the variable

See also

get_next_id()

Member Data Documentation

id_

Id smats::Variable::id_

private

Unique identifier for the variable. The high-order byte stores the Type.

See also

get_next_id()

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

• smats/symbolic/variable.h
• smats/symbolic/variable.cpp