org.cpsolver.coursett.constraint

## Class MaxHalfDaysFlexibleConstraint

- java.lang.Object
- - org.cpsolver.ifs.model.Constraint<V,T>
  - - org.cpsolver.ifs.assignment.context.ConstraintWithContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>
    - - org.cpsolver.coursett.constraint.FlexibleConstraint
      - - org.cpsolver.coursett.constraint.MaxHalfDaysFlexibleConstraint

- All Implemented Interfaces:
    Comparable<Constraint<Lecture,Placement>>, CanHoldContext, HasAssignmentContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>

      public class MaxHalfDaysFlexibleConstraint
      extends FlexibleConstraint

  The MaxHalfDays constraint limits the number of half-days of week during which the given set of classes are taught.
  It has one parameter: a maximal number of week half-days during which the given set of classes can be placed.
  A day is split by noon (which can be changed using General.HalfDaySlot parameter). A class starting before noon is considered a morning class (despite of its end), a class starting at noon or later is considered an afternoon class.
  Reference _MaxHalfDays:4_ translates to a maximum number of 4 half-days a week
  Version:
    CourseTT 1.3 (University Course Timetabling)
    Copyright (C) 2017 Tomáš Müller
    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

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `class` | `MaxHalfDaysFlexibleConstraint.MaxHalfDaysFlexibleConstraintContext`

    - ### Nested classes/interfaces inherited from class org.cpsolver.coursett.constraint.FlexibleConstraint

      `FlexibleConstraint.Block, FlexibleConstraint.FlexibleConstraintContext, FlexibleConstraint.FlexibleConstraintType, FlexibleConstraint.PlacementTimeComparator`

  - ### Field Summary

    - ### Fields inherited from class org.cpsolver.coursett.constraint.FlexibleConstraint

      `iConstraintType, iDayOfWeekOffset, iPreciseDateComputation, iPreference, iReference, iWeeks`

    - ### Fields inherited from class org.cpsolver.ifs.model.Constraint

      `iConstraintListeners, iId`

    - ### Fields inherited from interface org.cpsolver.ifs.assignment.context.CanHoldContext

      `sMaxSize`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `MaxHalfDaysFlexibleConstraint(Long id, String owner, String preference, String reference)`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `computeConflicts(Assignment<Lecture,Placement> assignment, Placement value, Set<Placement> conflicts)` The only method which has to be implemented by any constraint.
    `FlexibleConstraint.FlexibleConstraintContext` | `createAssignmentContext(Assignment<Lecture,Placement> assignment)` Create a new assignment context for the given assignment.
    `protected int` | `getHalfDay(TimeLocation time)` Returns index of the half day
    `protected int` | `getNrHalfDays()` Returns number of half-days in a day
    `double` | `getNrViolations(Assignment<Lecture,Placement> assignment, Set<Placement> conflicts, HashMap<Lecture,Placement> assignments)` Return current number of violations.
    `boolean` | `inConflict(Assignment<Lecture,Placement> assignment, Placement value)` Returns true if the given assignment is inconsistent with the existing assignments respecting this constraint.
    `void` | `setModel(Model<Lecture,Placement> model)` Sets the model which the constraint belongs to

    - ### Methods inherited from class org.cpsolver.coursett.constraint.FlexibleConstraint

      `getCurrentPreference, getDayOfWeekOffset, getName, getOwner, getPrologPreference, getReference, getRelevantPlacements, getType, getWeeks, isConsistent, isHard, isPreciseDateComputation, mergeToBlocks, shareWeeksAndDay, toString`

    - ### Methods inherited from class org.cpsolver.ifs.assignment.context.ConstraintWithContext

      `assigned, getAssignmentContextReference, getContext, getContext, setAssignmentContextReference, unassigned`

    - ### Methods inherited from class org.cpsolver.ifs.model.Constraint

      `addConstraintListener, addVariable, assignedVariables, compareTo, computeConflictsNoForwardCheck, constraintListeners, countAssignedVariables, countVariables, equals, getDescription, getId, getModel, hashCode, removeConstraintListener, removeVariable, variables`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### MaxHalfDaysFlexibleConstraint

          public MaxHalfDaysFlexibleConstraint(Long id,
                                               String owner,
                                               String preference,
                                               String reference)

  - ### Method Detail

    - #### setModel

          public void setModel(Model<Lecture,Placement> model)

      Description copied from class: `Constraint`
      Sets the model which the constraint belongs to
      Overrides:
        `setModel` in class `ConstraintWithContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>`
      Parameters:
        `model` - problem model

    - #### getNrHalfDays

          protected int getNrHalfDays()

      Returns number of half-days in a day

    - #### getHalfDay

          protected int getHalfDay(TimeLocation time)

      Returns index of the half day
      Parameters:
        `time` - given time
      Returns:
        0 for morning, 1 for evening

    - #### getNrViolations

          public double getNrViolations(Assignment<Lecture,Placement> assignment,
                                        Set<Placement> conflicts,
                                        HashMap<Lecture,Placement> assignments)

      Description copied from class: `FlexibleConstraint`
      Return current number of violations.
      Specified by:
        `getNrViolations` in class `FlexibleConstraint`
      Parameters:
        `assignment` - current assignment
        `conflicts` - conflicting placements to be unassigned
        `assignments` - assigned placements
      Returns:
        the number of violations of the constraint during days and all weeks of the semester

    - #### computeConflicts

          public void computeConflicts(Assignment<Lecture,Placement> assignment,
                                       Placement value,
                                       Set<Placement> conflicts)

      Description copied from class: `Constraint`
      The only method which has to be implemented by any constraint. It returns the values which needs to be unassigned in order to make this constraint consistent with the given value if it is assigned to its variable. The computed list of conflicting values is added to the given set of conflicts.
      Specified by:
        `computeConflicts` in class `Constraint<Lecture,Placement>`
      Parameters:
        `assignment` - current assignment
        `value` - value to be assigned to its variable
        `conflicts` - resultant set of conflicting values

    - #### inConflict

          public boolean inConflict(Assignment<Lecture,Placement> assignment,
                                    Placement value)

      Description copied from class: `Constraint`
      Returns true if the given assignment is inconsistent with the existing assignments respecting this constraint. This method is used by MAC (see `MacPropagation`).
      Overrides:
        `inConflict` in class `Constraint<Lecture,Placement>`
      Parameters:
        `assignment` - current assignment
        `value` - given value
      Returns:
        true if there is a conflict with other assigned variables of the constraint

    - #### createAssignmentContext

          public FlexibleConstraint.FlexibleConstraintContext createAssignmentContext(Assignment<Lecture,Placement> assignment)

      Description copied from interface: `HasAssignmentContext`
      Create a new assignment context for the given assignment. If there are already some variables assigned in the value, the method should make sure that the context is appropriately initialized.
      Specified by:
        `createAssignmentContext` in interface `HasAssignmentContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>`
      Overrides:
        `createAssignmentContext` in class `FlexibleConstraint`
      Parameters:
        `assignment` - an assignment for which there needs to be an assignment context
      Returns:
        a new instance of the assignment context, filled according to the given assignment