org.cpsolver.ifs.assignment

Interface Assignment<V extends Variable<V,T>,T extends Value<V,T>>

Type Parameters:

V - Variable

T - Value

All Known Subinterfaces:

InheritedAssignment<V,T>

All Known Implementing Classes:

AssignmentAbstract, AssignmentArray, AssignmentMap, DefaultInheritedAssignment, DefaultParallelAssignment, DefaultSingleAssignment, EmptyAssignment, InheritedAssignmentArray, OptimisticInheritedAssignment

public interface Assignment<V extends Variable<V,T>,T extends Value<V,T>>

An assignment of all the variable of a Model. This class decouples an assignment of variables (classes extending Variable) to their values (classes extending Value) from the Model. This is needed for any kind of parallel computations, or in general, to be able to hold multiple different assignments in memory.

This class also include translation of AssignmentContextReference to AssignmentContext, so that each constraint, criterion, neighborhood selection etc. can hold its own assignment dependent information. See ConstraintWithContext or NeighbourSelectionWithContext for more details.

Version:

IFS 1.3 (Iterative Forward Search)
Copyright (C) 2014 Tomáš Müller
muller@unitime.org
http://muller.unitime.org

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not see http://www.gnu.org/licenses.

Author:

Tomáš Müller

See Also:

Variable, Value, Model, AssignmentContext

Method Summary

Modifier and Type	Method and Description
T	assign(long iteration, T value) Assign the given value to its variable.
Collection<T>	assignedValues() The list of assigned values in the assignment.
Collection<V>	assignedVariables() The list of assigned variables in the assignment.
<C extends AssignmentContext> void	clearContext(AssignmentContextReference<V,T,C> reference) Clear an assignment context that is associated with the given a reference.
<C extends AssignmentContext> C	getAssignmentContext(AssignmentContextReference<V,T,C> reference) Assignment context for a reference.
int	getIndex() Assignment index.
long	getIteration(V variable) Returns iteration of the last assignment.
T	getValue(V variable) Returns assignment of a variable, null if not assigned Replacement for Variable.getAssignment().
int	nrAssignedVariables() Number of assigned variables in this assignment.
int	nrUnassignedVariables(Model<V,T> model) Number of assigned variables in the assignment.
T	unassign(long iteration, V variable) Unassign the given variable.
T	unassign(long iteration, V variable, T value) Unassign the given variable, but only if the current assignment differs from the given value.
Collection<V>	unassignedVariables(Model<V,T> model) The list of variables of the model that have no value in this assignment.

Method Detail

getIndex

int getIndex()

Assignment index. Unique identification of the assignment, starting with zero. This can be used to increase the speed of the search by storing individual values on the variables and an array (indexed by this number).

Returns:

assignment index, -1 if not to be used

getValue

T getValue(V variable)

Returns assignment of a variable, null if not assigned Replacement for Variable.getAssignment().

Parameters:

variable - problem variable

Returns:

currently assigned value

getIteration

long getIteration(V variable)

Returns iteration of the last assignment. Replacement for Variable.getLastIteration().

Parameters:

variable - problem variable

Returns:

iteration of the last assignment

assign

T assign(long iteration,
         T value)

Assign the given value to its variable. Replacement for Variable.assign(int, Value).

Parameters:

iteration - current iteration

value - a new value to be assigned to variable Value.variable().

Returns:

previous assignment of the variable, null if it was not assigned

unassign

T unassign(long iteration,
           V variable)

Unassign the given variable. Replacement for Variable.unassign(int).

Parameters:

iteration - current iteration

variable - variable to be unassigned

Returns:

previous assignment of the variable, null if it was not assigned

unassign

T unassign(long iteration,
           V variable,
           T value)

Unassign the given variable, but only if the current assignment differs from the given value. Replacement for Variable.unassign(int).

Parameters:

iteration - current iteration

variable - variable to be unassigned

value - target value

Returns:

previous assignment of the variable, null if it was not assigned

nrAssignedVariables

int nrAssignedVariables()

Number of assigned variables in this assignment. Replacement for Model.nrAssignedVariables().

Returns:

number of assigned variables in this assignment

assignedVariables

Collection<V> assignedVariables()

The list of assigned variables in the assignment. That is all the variables that getValue(Variable) is not null in this assignment. Replacement for Model.assignedVariables().

Returns:

a collection of assigned variable in this assignment

assignedValues

Collection<T> assignedValues()

The list of assigned values in the assignment. That is a collection of getValue(Variable) for all assigned variables in this assignment.

Returns:

a collection of assigned values in this assignment

nrUnassignedVariables

int nrUnassignedVariables(Model<V,T> model)

Number of assigned variables in the assignment. Replacement for Model.nrUnassignedVariables().

Parameters:

model - existing model (the assignment does not keep track about all existing variables, that is what the Model.variables() is for)

Returns:

number of not assigned variables in this assignment

unassignedVariables

Collection<V> unassignedVariables(Model<V,T> model)

The list of variables of the model that have no value in this assignment. That is all the variables of the model that getValue(Variable) is null in this assignment. Replacement for Model.unassignedVariables()

Parameters:

model - existing model (the assignment does not keep track about all existing variables, that is what the Model.variables() is for)

Returns:

a collection of all not assigned variables in this assignment

getAssignmentContext

<C extends AssignmentContext> C getAssignmentContext(AssignmentContextReference<V,T,C> reference)

Assignment context for a reference. This can be used to keep assignment dependent computations (e.g., see ConstraintWithContext).

Type Parameters:

C - assignment context type

Parameters:

reference - a reference (which can be stored within the model, e.g., as an instance variable of a constraint)

Returns:

an AssignmentContext

clearContext

<C extends AssignmentContext> void clearContext(AssignmentContextReference<V,T,C> reference)

Clear an assignment context that is associated with the given a reference. If there is any created for the reference.

Type Parameters:

C - assignment context type

Parameters:

reference - a reference (which can be stored within the model, e.g., as an instance variable of a constraint)