cp_set_solution_callback

model "Using callbacks"
 uses "kalis"

 declarations
  NBTASKS = 5
  TASKS = 1..NBTASKS                     ! Set of tasks
  DUR: array(TASKS) of integer           ! Task durations
  DURs: array(set of cpvar) of integer   ! Durations
  DUE: array(TASKS) of integer           ! Due dates
  WEIGHT: array(TASKS) of integer        ! Weights of tasks
  start: array(TASKS) of cpvar           ! Start times
  tmp: array(TASKS) of cpvar             ! Aux. variable
  tardiness: array(TASKS) of cpvar       ! Tardiness
  twt: cpvar                             ! Objective variable
  zeroVar: cpvar                         ! 0-valued variable
  Strategy: array(range) of cpbranching  ! Branching strategy
  Disj: set of cpctr                     ! Disjunctions
  nodesx: array(range) of integer        ! x-coordinates
  nodesy: array(range) of integer        ! y-coordinates
  currentpos: integer
 end-declarations

! Initialization of search tree data
 nodesx(0) := 1
 nodesy(0) := 0
 currentpos := 1

! **********************************************************
! solution_found: called each time a solution is found
! **********************************************************
 procedure solution_found
  writeln("A solution has been found :")
  forall (t in TASKS)
   writeln("[", getsol(start(t)), "==>",
           (getsol(start(t)) + DUR(t)), "]:\t ",
           getsol(tardiness(t)), "  (", getsol(tmp(t)), ")")
  writeln("Total weighted tardiness: ", getsol(twt))
 end-procedure

! **********************************************************
! node_explored: called each time a node is explored
! **********************************************************
 procedure node_explored
  nodesx(currentpos) += 1
  if nodesx(currentpos-1)>nodesx(currentpos) then
   nodesx(currentpos) := nodesx(currentpos-1)
  end-if
  nodesy(currentpos) := -currentpos
  writeln("[Node explored depth : " , (-nodesy(currentpos)), "]")
 end-procedure

! **********************************************************
! go_down_branch: called each time the search goes down
!                 a branch of the search tree
! **********************************************************
 procedure go_down_branch
  writeln("[Branch go_down " , (-nodesy(currentpos)) , "]")
  currentpos := currentpos + 1
 end-procedure

! **********************************************************
! go_up_branch: called each time the search goes up
!               a branch of the search tree
! **********************************************************
 procedure go_up_branch
  currentpos := currentpos - 1
  writeln("[Branch go_up " , (-nodesy(currentpos)) , "]")
 end-procedure

! **********************************************************
! Problem definition
! **********************************************************

 DUR :: [21,53,95,55,34]
 DUE :: [66,101,232,125,150]
 WEIGHT :: [1,1,1,1,1]

 setname(twt, "Total weighted tardiness")
 zeroVar = 0
 setname(zeroVar, "zeroVar")

! Setting up the decision variables
 forall (t in TASKS) do
  start(t) >= 0
  setname(start(t), "Start("+t+")")
  DURs(start(t)):= DUR(t)
  tmp(t) = start(t) + DUR(t) - DUE(t)
  setname(tardiness(t), "Tard("+t+")")
  tardiness(t) = maximum({tmp(t), zeroVar})
 end-do

 twt = sum(t in TASKS) (WEIGHT(t) * tardiness(t))

 ! Create the disjunctive constraints
 disjunctive(union(t in TASKS) {start(t)}, DURs, Disj, 1)

 ! The setxxxcallback methods must be called before
 ! setting the branching with 'cp_set_branching'
 cp_set_solution_callback(->solution_found)
 cp_set_node_callback(->node_explored)
 cp_set_branch_callback(->go_down_branch, ->go_up_branch)

 Strategy(0):= settle_disjunction
 Strategy(1):= split_domain(KALIS_MAX_DEGREE,KALIS_MIN_TO_MAX)
 cp_set_branching(Strategy)

 if not cp_minimize(twt) then
  writeln("problem is inconsistent")
  exit(0)
 end-if

end-model