#include <constraint_solveri.h>

Inheritance diagram for operations_research::PathOperator:

Classes
struct	IterationParameters
	Set of parameters used to configure how the neighnorhood is traversed. More...

Public Member Functions
	PathOperator (const std::vector< IntVar * > &next_vars, const std::vector< IntVar * > &path_vars, IterationParameters iteration_parameters)
	Builds an instance of PathOperator from next and path variables.

	PathOperator (const std::vector< IntVar * > &next_vars, const std::vector< IntVar * > &path_vars, int number_of_base_nodes, bool skip_locally_optimal_paths, bool accept_path_end_base, std::function< int(int64_t)> start_empty_path_class, std::function< const std::vector< int > &(int, int)> get_neighbors)

	~PathOperator () override

virtual bool	MakeNeighbor ()=0

void	Reset () override

bool	SkipUnchanged (int index) const override

int64_t	Next (int64_t node) const
	Returns the node after node in the current delta.

int64_t	Prev (int64_t node) const
	Returns the node before node in the current delta.

int64_t	Path (int64_t node) const

int	number_of_nexts () const
	Number of next variables.

Public Member Functions inherited from operations_research::IntVarLocalSearchOperator
	IntVarLocalSearchOperator (const std::vector< IntVar * > &vars, bool keep_inverse_values=false)

	~IntVarLocalSearchOperator () override

bool	HoldsDelta () const override

void	Start (const Assignment *assignment) override

virtual bool	IsIncremental () const

int	Size () const

int64_t	Value (int64_t index) const

IntVar *	Var (int64_t index) const
	Returns the variable of given index.

int64_t	OldValue (int64_t index) const

int64_t	PrevValue (int64_t index) const

void	SetValue (int64_t index, int64_t value)

bool	Activated (int64_t index) const

void	Activate (int64_t index)

void	Deactivate (int64_t index)

bool	ApplyChanges (Assignment delta, Assignment deltadelta) const

void	RevertChanges (bool change_was_incremental)

void	AddVars (const std::vector< IntVar * > &vars)

bool	MakeNextNeighbor (Assignment delta, Assignment deltadelta) override
	--— Base operator class for operators manipulating IntVars --—

Public Member Functions inherited from operations_research::LocalSearchOperator
	LocalSearchOperator ()

	~LocalSearchOperator () override

virtual const LocalSearchOperator *	Self () const

virtual bool	HasFragments () const

Public Member Functions inherited from operations_research::BaseObject
	BaseObject ()

	BaseObject (const BaseObject &)=delete
	This type is neither copyable nor movable.

BaseObject &	operator= (const BaseObject &)=delete

virtual	~BaseObject ()

virtual std::string	DebugString () const

Protected Member Functions
bool	MakeOneNeighbor () override
	This method should not be overridden. Override MakeNeighbor() instead.

virtual void	OnNodeInitialization ()

int64_t	BaseNode (int i) const
	Returns the ith base node of the operator.

int	BaseAlternative (int i) const
	Returns the alternative for the ith base node.

int64_t	BaseAlternativeNode (int i) const
	Returns the alternative node for the ith base node.

int	BaseSiblingAlternative (int i) const
	Returns the alternative for the sibling of the ith base node.

int64_t	BaseSiblingAlternativeNode (int i) const
	Returns the alternative node for the sibling of the ith base node.

int64_t	StartNode (int i) const
	Returns the start node of the ith base node.

int64_t	EndNode (int i) const
	Returns the end node of the ith base node.

const std::vector< int64_t > &	path_starts () const
	Returns the vector of path start nodes.

int	PathClass (int i) const
	Returns the class of the path of the ith base node.

int	PathClassFromStartNode (int64_t start_node) const

virtual bool	RestartAtPathStartOnSynchronize ()

virtual bool	OnSamePathAsPreviousBase (int64_t base_index)

virtual int64_t	GetBaseNodeRestartPosition (int base_index)

virtual void	SetNextBaseToIncrement (int64_t base_index)

virtual bool	ConsiderAlternatives (int64_t base_index) const

int64_t	OldNext (int64_t node) const

int64_t	PrevNext (int64_t node) const

int64_t	OldPrev (int64_t node) const

int64_t	OldPath (int64_t node) const

int	CurrentNodePathStart (int64_t node) const

int	CurrentNodePathEnd (int64_t node) const

bool	MoveChain (int64_t before_chain, int64_t chain_end, int64_t destination)

bool	ReverseChain (int64_t before_chain, int64_t after_chain, int64_t *chain_last)

bool	MakeActive (int64_t node, int64_t destination)
	Insert the inactive node after destination.

bool	MakeChainInactive (int64_t before_chain, int64_t chain_end)

bool	SwapActiveAndInactive (int64_t active, int64_t inactive)
	Replaces active by inactive in the current path, making active inactive.

void	SetNext (int64_t from, int64_t to, int64_t path)
	Sets 'to' to be the node after 'from' on the given path.

bool	IsPathEnd (int64_t node) const

bool	IsPathStart (int64_t node) const
	Returns true if node is the first node on the path.

bool	IsInactive (int64_t node) const
	Returns true if node is inactive.

virtual bool	InitPosition () const

void	ResetPosition ()

int	AddAlternativeSet (const std::vector< int64_t > &alternative_set)

template<typename PairType >
void	AddPairAlternativeSets (const std::vector< PairType > &pair_alternative_sets)

int64_t	GetActiveInAlternativeSet (int alternative_index) const
	Returns the active node in the given alternative set.

int64_t	GetActiveAlternativeNode (int node) const
	Returns the active node in the alternative set of the given node.

int	GetSiblingAlternativeIndex (int node) const
	Returns the index of the alternative set of the sibling of node.

int64_t	GetActiveAlternativeSibling (int node) const

bool	CheckChainValidity (int64_t before_chain, int64_t chain_end, int64_t exclude) const

bool	HasNeighbors () const

int	GetNeighborForBaseNode (int64_t base_index) const

Protected Member Functions inherited from operations_research::IntVarLocalSearchOperator
int64_t	InverseValue (int64_t index) const

int64_t	OldInverseValue (int64_t index) const

void	AddToAssignment (IntVar var, int64_t value, bool active, std::vector< int > assignment_indices, int64_t index, Assignment *assignment) const

Protected Attributes
const int	number_of_nexts_

const bool	ignore_path_vars_

Detailed Description

Base class of the local search operators dedicated to path modifications (a path is a set of nodes linked together by arcs). This family of neighborhoods supposes they are handling next variables representing the arcs (var[i] represents the node immediately after i on a path). Several services are provided:

arc manipulators (SetNext(), ReverseChain(), MoveChain())
path inspectors (Next(), Prev(), IsPathEnd())
path iterators: operators need a given number of nodes to define a neighbor; this class provides the iteration on a given number of (base) nodes which can be used to define a neighbor (through the BaseNode method) Subclasses only need to override MakeNeighbor to create neighbors using the services above (no direct manipulation of assignments).

Definition at line 1318 of file constraint_solveri.h.

Constructor & Destructor Documentation

◆ PathOperator() [1/2]

operations_research::PathOperator::PathOperator	(	const std::vector< IntVar * > &	next_vars,
		const std::vector< IntVar * > &	path_vars,
		IterationParameters	iteration_parameters )

Builds an instance of PathOperator from next and path variables.

--— Path-based Operators --—

Definition at line 348 of file local_search.cc.

◆ PathOperator() [2/2]

operations_research::PathOperator::PathOperator	(	const std::vector< IntVar * > &	next_vars,
		const std::vector< IntVar * > &	path_vars,
		int	number_of_base_nodes,
		bool	skip_locally_optimal_paths,
		bool	accept_path_end_base,
		std::function< int(int64_t)>	start_empty_path_class,
		std::function< const std::vector< int > &(int, int)>	get_neighbors )

inline

Definition at line 1348 of file constraint_solveri.h.

◆ ~PathOperator()

operations_research::PathOperator::~PathOperator ( )

inlineoverride

Definition at line 1357 of file constraint_solveri.h.

Member Function Documentation

◆ AddAlternativeSet()

int operations_research::PathOperator::AddAlternativeSet ( const std::vector< int64_t > & alternative_set )

inlineprotected

Handling node alternatives. Adds a set of node alternatives to the neighborhood. No node can be in two altrnatives.

Definition at line 1541 of file constraint_solveri.h.

◆ AddPairAlternativeSets()

template<typename PairType >

void operations_research::PathOperator::AddPairAlternativeSets ( const std::vector< PairType > & pair_alternative_sets )

inlineprotected

Adds all sets of node alternatives of a vector of alternative pairs. No node can be in two alternatives.

Definition at line 1555 of file constraint_solveri.h.

◆ BaseAlternative()

int operations_research::PathOperator::BaseAlternative ( int i ) const

inlineprotected

Returns the alternative for the ith base node.

Definition at line 1397 of file constraint_solveri.h.

◆ BaseAlternativeNode()

int64_t operations_research::PathOperator::BaseAlternativeNode ( int i ) const

inlineprotected

Returns the alternative node for the ith base node.

Definition at line 1399 of file constraint_solveri.h.

◆ BaseNode()

int64_t operations_research::PathOperator::BaseNode ( int i ) const

inlineprotected

Returns the ith base node of the operator.

Definition at line 1395 of file constraint_solveri.h.

◆ BaseSiblingAlternative()

int operations_research::PathOperator::BaseSiblingAlternative ( int i ) const

inlineprotected

Returns the alternative for the sibling of the ith base node.

Definition at line 1407 of file constraint_solveri.h.

◆ BaseSiblingAlternativeNode()

int64_t operations_research::PathOperator::BaseSiblingAlternativeNode ( int i ) const

inlineprotected

Returns the alternative node for the sibling of the ith base node.

Definition at line 1411 of file constraint_solveri.h.

◆ CheckChainValidity()

bool operations_research::PathOperator::CheckChainValidity	(	int64_t	before_chain,
		int64_t	chain_end,
		int64_t	exclude ) const

protected

Returns true if the chain is a valid path without cycles from before_chain to chain_end and does not contain exclude.

Rejects chain if chain_end is not after before_chain on the path or if the chain contains exclude. Given before_chain is the node before the chain, if before_chain and chain_end are the same the chain is rejected too. Also rejects cycles (cycle detection is detected through chain length overflow).

Definition at line 866 of file local_search.cc.

◆ ConsiderAlternatives()

virtual bool operations_research::PathOperator::ConsiderAlternatives ( int64_t base_index ) const

inlineprotectedvirtual

Indicates if alternatives should be considered when iterating over base nodes.

Reimplemented in operations_research::PairRelocateOperator.

Definition at line 1464 of file constraint_solveri.h.

◆ CurrentNodePathEnd()

int operations_research::PathOperator::CurrentNodePathEnd ( int64_t node ) const

inlineprotected

Definition at line 1489 of file constraint_solveri.h.

◆ CurrentNodePathStart()

int operations_research::PathOperator::CurrentNodePathStart ( int64_t node ) const

inlineprotected

Definition at line 1485 of file constraint_solveri.h.

◆ EndNode()

int64_t operations_research::PathOperator::EndNode ( int i ) const

inlineprotected

Returns the end node of the ith base node.

Definition at line 1423 of file constraint_solveri.h.

◆ GetActiveAlternativeNode()

int64_t operations_research::PathOperator::GetActiveAlternativeNode ( int node ) const

inlineprotected

Returns the active node in the alternative set of the given node.

Definition at line 1571 of file constraint_solveri.h.

◆ GetActiveAlternativeSibling()

int64_t operations_research::PathOperator::GetActiveAlternativeSibling ( int node ) const

inlineprotected

Returns the active node in the alternative set of the sibling of the given node.

Definition at line 1582 of file constraint_solveri.h.

◆ GetActiveInAlternativeSet()

int64_t operations_research::PathOperator::GetActiveInAlternativeSet ( int alternative_index ) const

inlineprotected

Returns the active node in the given alternative set.

Definition at line 1565 of file constraint_solveri.h.

◆ GetBaseNodeRestartPosition()

virtual int64_t operations_research::PathOperator::GetBaseNodeRestartPosition ( int base_index )

inlineprotectedvirtual

Returns the index of the node to which the base node of index base_index must be set to when it reaches the end of a path. By default, it is set to the start of the current path. When this method is called, one can only assume that base nodes with indices < base_index have their final position.

Reimplemented in operations_research::MakeChainInactiveOperator, operations_research::MakePairActiveOperator, operations_research::PairExchangeRelocateOperator, operations_research::PairNodeSwapActiveOperator< swap_first >, operations_research::PairRelocateOperator, and operations_research::TwoOpt.

Definition at line 1454 of file constraint_solveri.h.

◆ GetNeighborForBaseNode()

int operations_research::PathOperator::GetNeighborForBaseNode ( int64_t base_index ) const

inlineprotected

Definition at line 1598 of file constraint_solveri.h.

◆ GetSiblingAlternativeIndex()

int operations_research::PathOperator::GetSiblingAlternativeIndex ( int node ) const

inlineprotected

Returns the index of the alternative set of the sibling of node.

Definition at line 1575 of file constraint_solveri.h.

◆ HasNeighbors()

bool operations_research::PathOperator::HasNeighbors ( ) const

inlineprotected

Definition at line 1594 of file constraint_solveri.h.

◆ InitPosition()

virtual bool operations_research::PathOperator::InitPosition ( ) const

inlineprotectedvirtual

Returns true if the operator needs to restart its initial position at each call to Start()

Definition at line 1532 of file constraint_solveri.h.

◆ IsInactive()

bool operations_research::PathOperator::IsInactive ( int64_t node ) const

inlineprotected

Returns true if node is inactive.

Definition at line 1526 of file constraint_solveri.h.

◆ IsPathEnd()

bool operations_research::PathOperator::IsPathEnd ( int64_t node ) const

inlineprotected

Returns true if node is the last node on the path; defined by the fact that node is outside the range of the variable array.

Definition at line 1520 of file constraint_solveri.h.

◆ IsPathStart()

bool operations_research::PathOperator::IsPathStart ( int64_t node ) const

inlineprotected

Returns true if node is the first node on the path.

Definition at line 1523 of file constraint_solveri.h.

◆ MakeActive()

bool operations_research::PathOperator::MakeActive	(	int64_t	node,
		int64_t	destination )

protected

Insert the inactive node after destination.

Definition at line 465 of file local_search.cc.

◆ MakeChainInactive()

bool operations_research::PathOperator::MakeChainInactive	(	int64_t	before_chain,
		int64_t	chain_end )

protected

Makes the nodes on the chain starting after before_chain and ending at chain_end inactive.

Definition at line 475 of file local_search.cc.

◆ MakeNeighbor()

virtual bool operations_research::PathOperator::MakeNeighbor ( )

pure virtual

◆ MakeOneNeighbor()

bool operations_research::PathOperator::MakeOneNeighbor ( )

overrideprotectedvirtual

This method should not be overridden. Override MakeNeighbor() instead.

Need to revert changes here since MakeNeighbor might have returned false and have done changes in the previous iteration.

Reimplemented from operations_research::IntVarLocalSearchOperator.

Reimplemented in operations_research::RelocateExpensiveChain, and operations_research::TSPLns.

Definition at line 395 of file local_search.cc.

◆ MoveChain()

bool operations_research::PathOperator::MoveChain	(	int64_t	before_chain,
		int64_t	chain_end,
		int64_t	destination )

protected

Moves the chain starting after the node before_chain and ending at the node chain_end after the node destination

Definition at line 419 of file local_search.cc.

◆ Next()

int64_t operations_research::PathOperator::Next ( int64_t node ) const

inline

Returns the node after node in the current delta.

Definition at line 1365 of file constraint_solveri.h.

◆ number_of_nexts()

int operations_research::PathOperator::number_of_nexts ( ) const

inline

Number of next variables.

Definition at line 1384 of file constraint_solveri.h.

◆ OldNext()

int64_t operations_research::PathOperator::OldNext ( int64_t node ) const

inlineprotected

Definition at line 1466 of file constraint_solveri.h.

◆ OldPath()

int64_t operations_research::PathOperator::OldPath ( int64_t node ) const

inlineprotected

Definition at line 1481 of file constraint_solveri.h.

◆ OldPrev()

int64_t operations_research::PathOperator::OldPrev ( int64_t node ) const

inlineprotected

Definition at line 1476 of file constraint_solveri.h.

◆ OnNodeInitialization()

virtual void operations_research::PathOperator::OnNodeInitialization ( )

inlineprotectedvirtual

Called by OnStart() after initializing node information. Should be overridden instead of OnStart() to avoid calling PathOperator::OnStart explicitly.

Definition at line 1392 of file constraint_solveri.h.

◆ OnSamePathAsPreviousBase()

virtual bool operations_research::PathOperator::OnSamePathAsPreviousBase ( int64_t base_index )

inlineprotectedvirtual

Returns true if a base node has to be on the same path as the "previous" base node (base node of index base_index - 1). Useful to limit neighborhood exploration to nodes on the same path.

Todo: (user): ideally this should be OnSamePath(int64_t node1, int64_t node2); it's currently way more complicated to implement.

Reimplemented in operations_research::MakeChainInactiveOperator, operations_research::MakePairActiveOperator, operations_research::PairExchangeRelocateOperator, operations_research::PairNodeSwapActiveOperator< swap_first >, operations_research::PairRelocateOperator, operations_research::Relocate, and operations_research::TwoOpt.

Definition at line 1448 of file constraint_solveri.h.

◆ Path()

int64_t operations_research::PathOperator::Path ( int64_t node ) const

inline

Returns the index of the path to which node belongs in the current delta. Only returns a valid value if path variables are taken into account.

Definition at line 1379 of file constraint_solveri.h.

◆ path_starts()

const std::vector< int64_t > & operations_research::PathOperator::path_starts ( ) const

inlineprotected

Returns the vector of path start nodes.

Definition at line 1425 of file constraint_solveri.h.

◆ PathClass()

int operations_research::PathOperator::PathClass ( int i ) const

inlineprotected

Returns the class of the path of the ith base node.

Definition at line 1427 of file constraint_solveri.h.

◆ PathClassFromStartNode()

int operations_research::PathOperator::PathClassFromStartNode ( int64_t start_node ) const

inlineprotected

Definition at line 1428 of file constraint_solveri.h.

◆ Prev()

int64_t operations_research::PathOperator::Prev ( int64_t node ) const

inline

Returns the node before node in the current delta.

Definition at line 1371 of file constraint_solveri.h.

◆ PrevNext()

int64_t operations_research::PathOperator::PrevNext ( int64_t node ) const

inlineprotected

Definition at line 1471 of file constraint_solveri.h.

◆ Reset()

void operations_research::PathOperator::Reset ( )

overridevirtual

Reimplemented from operations_research::LocalSearchOperator.

Reimplemented in operations_research::TwoOpt.

Definition at line 386 of file local_search.cc.

◆ ResetPosition()

void operations_research::PathOperator::ResetPosition ( )

inlineprotected

Reset the position of the operator to its position when Start() was last called; this can be used to let an operator iterate more than once over the paths.

Definition at line 1536 of file constraint_solveri.h.

◆ RestartAtPathStartOnSynchronize()

virtual bool operations_research::PathOperator::RestartAtPathStartOnSynchronize ( )

inlineprotectedvirtual

When the operator is being synchronized with a new solution (when Start() is called), returns true to restart the exploration of the neighborhood from the start of the last paths explored; returns false to restart the exploration at the last nodes visited. This is used to avoid restarting on base nodes which have changed paths, leading to potentially skipping neighbors.

Todo: (user): remove this when automatic detection of such cases in done.

Reimplemented in operations_research::MakePairActiveOperator, and operations_research::PairNodeSwapActiveOperator< swap_first >.

Definition at line 1441 of file constraint_solveri.h.

◆ ReverseChain()

bool operations_research::PathOperator::ReverseChain	(	int64_t	before_chain,
		int64_t	after_chain,
		int64_t *	chain_last )

protected

Reverses the chain starting after before_chain and ending before after_chain

Definition at line 442 of file local_search.cc.

◆ SetNext()

void operations_research::PathOperator::SetNext	(	int64_t	from,
		int64_t	to,
		int64_t	path )

inlineprotected

Sets 'to' to be the node after 'from' on the given path.

Definition at line 1509 of file constraint_solveri.h.

◆ SetNextBaseToIncrement()

virtual void operations_research::PathOperator::SetNextBaseToIncrement ( int64_t base_index )

inlineprotectedvirtual

Set the next base to increment on next iteration. All base > base_index will be reset to their start value.

Definition at line 1459 of file constraint_solveri.h.

◆ SkipUnchanged()

bool operations_research::PathOperator::SkipUnchanged ( int index ) const

overridevirtual

Todo: (user): Make the following methods protected.

Reimplemented from operations_research::IntVarLocalSearchOperator.

Definition at line 407 of file local_search.cc.

◆ StartNode()

int64_t operations_research::PathOperator::StartNode ( int i ) const

inlineprotected

Returns the start node of the ith base node.

Definition at line 1421 of file constraint_solveri.h.

◆ SwapActiveAndInactive()

bool operations_research::PathOperator::SwapActiveAndInactive	(	int64_t	active,
		int64_t	inactive )

protected

Replaces active by inactive in the current path, making active inactive.

Definition at line 492 of file local_search.cc.

Member Data Documentation

◆ ignore_path_vars_

const bool operations_research::PathOperator::ignore_path_vars_

protected

Definition at line 1606 of file constraint_solveri.h.

◆ number_of_nexts_

const int operations_research::PathOperator::number_of_nexts_

protected

Definition at line 1605 of file constraint_solveri.h.

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

ortools/constraint_solver/constraint_solveri.h
ortools/constraint_solver/local_search.cc

Classes

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ PathOperator() [1/2]

◆ PathOperator() [2/2]

◆ ~PathOperator()

Member Function Documentation

◆ AddAlternativeSet()

◆ AddPairAlternativeSets()

◆ BaseAlternative()

◆ BaseAlternativeNode()

◆ BaseNode()

◆ BaseSiblingAlternative()

◆ BaseSiblingAlternativeNode()

◆ CheckChainValidity()

◆ ConsiderAlternatives()

◆ CurrentNodePathEnd()

◆ CurrentNodePathStart()

◆ EndNode()

◆ GetActiveAlternativeNode()

◆ GetActiveAlternativeSibling()

◆ GetActiveInAlternativeSet()

◆ GetBaseNodeRestartPosition()

◆ GetNeighborForBaseNode()

◆ GetSiblingAlternativeIndex()

◆ HasNeighbors()

◆ InitPosition()

◆ IsInactive()

◆ IsPathEnd()

◆ IsPathStart()

◆ MakeActive()

◆ MakeChainInactive()

◆ MakeNeighbor()

◆ MakeOneNeighbor()

◆ MoveChain()

◆ Next()

◆ number_of_nexts()

◆ OldNext()

◆ OldPath()

◆ OldPrev()

◆ OnNodeInitialization()

◆ OnSamePathAsPreviousBase()

◆ Path()

◆ path_starts()

◆ PathClass()

◆ PathClassFromStartNode()

◆ Prev()

◆ PrevNext()

◆ Reset()

◆ ResetPosition()

◆ RestartAtPathStartOnSynchronize()

◆ ReverseChain()

◆ SetNext()

◆ SetNextBaseToIncrement()

◆ SkipUnchanged()

◆ StartNode()

◆ SwapActiveAndInactive()

Member Data Documentation

◆ ignore_path_vars_

◆ number_of_nexts_