Rule

Defined in rewriters.hpp.

This class implements a data structure for storing rewriting rules. Here, a rewriting rule is a rule of the form \(A \to B\), where \(A\) and \(B\) are both words over some alphabet \(\Sigma\).

The left-hand and right-hand sides of a rule are specified externally with the type external_string_type, and stored internally with type internal_string_type.

Public Member Functions
	Rule (int64_t id)
	Construct with new empty left-hand and right-hand sides.
	Rule (Rule &&copy)=delete
	Rule (Rule const &copy)=delete
void	activate () noexcept
	Activate a rule.
bool	active () const noexcept
	Check if the Rule is active.
void	deactivate () noexcept
	Deactivate a rule.
bool	empty () const noexcept
	Check if the left-hand and right-hand sides are empty.
int64_t	id () const noexcept
	Return the id of a rule.
internal_string_type *	lhs () const noexcept
	Return the left-hand side of the rule.
Rule &	operator= (Rule &&copy)=delete
Rule &	operator= (Rule const &copy)=delete
void	reorder ()
	Reorder the left-hand and right-hand sides.
internal_string_type *	rhs () const noexcept
	Return the right-hand side of the rule.
void	set_id (int64_t id)
	Set the id of a rule.
void	set_id_no_checks (int64_t id) noexcept
	Set the id of a rule.

Constructor & Destructor Documentation

Rule()

Rule ( int64_t id )

explicit

Construct with new empty left-hand and right-hand sides.

Parameters

id	the id of the new rule.

Exceptions

This function guarantees not to throw a LibsemigroupsException.

Member Function Documentation

activate()

void activate ( )

noexcept

Activate a rule, if it is inactive.

Exceptions

This function is noexcept and is guaranteed never to throw.

Complexity

Constant.

See also

active

active()

bool active ( ) const

inlinenodiscardnoexcept

Check if the rule is active.

Returns

A value of type bool.

Exceptions

This function is noexcept and is guaranteed never to throw.

Complexity

Constant.

deactivate()

void deactivate ( )

noexcept

Deactivate a rule, if it is active.

Exceptions

This function is noexcept and is guaranteed never to throw.

Complexity

Constant.

See also

active

empty()

bool empty ( ) const

inlinenodiscardnoexcept

Check if the words pointed to by both the left-hand and the right-hand sides are empty.

Returns

A value of type bool.

Exceptions

This function is noexcept and is guaranteed never to throw.

Complexity

Constant.

id()

int64_t id ( ) const

inlinenodiscardnoexcept

Return the id of a rule.

Returns

A value of type int64_t

Exceptions

This function is noexcept and is guaranteed never to throw.

Complexity

Constant.

lhs()

internal_string_type * lhs ( ) const

inlinenodiscardnoexcept

Return the left-hand side of the rule. If this rule was create by a KnuthBendix, this is guaranteed to be greater than its right-hand side according to the reduction ordering of that KnuthBendix.

Returns

A pointer to the left-hand side.

Exceptions

This function is noexcept and is guaranteed never to throw.

Complexity

Constant.

See also

KnuthBendix

reorder()

void reorder ( )

inline

If the right-hand side is greater than the left-hand side of a rule, with regards to length-lexicographical order, then swap them.

Exceptions

Throws if shortlex_compare(T* const, T* const) does.

Complexity

The same complexity as shortlex_compare(T* const, T* const)

See also

shortlex_compare(T* const, T* const)

rhs()

internal_string_type * rhs ( ) const

inlinenodiscardnoexcept

Return the right-hand side of the rule. If this rule was create by a KnuthBendix, this is guaranteed to be less than its left-hand side according to the reduction ordering of that KnuthBendix.

Returns

A pointer to the right-hand side.

Exceptions

This function is noexcept and is guaranteed never to throw.

Complexity

Constant.

See also

KnuthBendix

set_id()

void set_id ( int64_t id )

inline

After checking that the Rule is inactive id is positive, this function performs the same as set_id_no_checks.

Exceptions

LIBSEMIGROUPS_EXCEPTION

if id is non-positive, or if this is active.

set_id_no_checks()

void set_id_no_checks ( int64_t id )

inlinenoexcept

Set the id of a rule.

Parameters

id	the id to set.

Exceptions

This function is noexcept and is guaranteed never to throw.

Complexity

Constant.

Note

This function does no checks on its parameters; however, the id of a rule should only be set if the rule is inactive, and the id of a rule should always be positive.

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

• /Users/jdm/libsemigroups/include/libsemigroups/detail/rewriters.hpp