Working with 'reversible' objects

• Accessing information from arrays of reversibles
• Setting new values for reversibles
• Behavior of reversibles on backtracking

(!****************************************************************
   CP example problems
   ===================
   
   file reversibles.mos
   ````````````````````
   Working with "reversible" objects (scalars and arrays).
   - Accessing information from arrays of reversibles
   - Setting new values for reversibles
   - Behavior of reversibles on backtracking

   (c) 2009 Artelys S.A. and Fair Isaac Corporation
       Creation: Nov. 2009
*****************************************************************!)
model "Reversible objects example"
 uses "kalis"
 
 declarations 
  reva : cpreversiblearray
  rev  : cpreversible
 end-declarations

!**** Reversible array ****

! Create a reversible array of 10 elements initialized with value 0
 set_reversible_attributes(reva,-5,5,0)

! Return the number of elements in the reversible array
 nbrev := getsize(reva)
 writeln("Array contains ", nbrev, " elements")

! Get the 5'th element of the array
 revvalue := getelt(reva,5)
 writeln("The 5'th element of reva is ", revvalue)

 writeln("Initial array contents: ", reva)

! Save current state of constraint system
 cp_save_state

! Set the value of the i'th element of the array to i
 forall (i in -5..5) setelt(reva,i,i)

! After setting values, get the 5'th element of the array
 revvalue := getelt(reva,5)
 writeln("The 5'th element of reva is ", revvalue)

 writeln("Before state restoration reversible array is: ", reva)

! Revert to the saved system state
 cp_restore_state

 writeln("After state restoration reversible array is: ", reva)

!**** Reversible scalar ****

! Create a reversible scalar initialized to 20.54
 set_reversible_attributes(rev,20.54)

 writeln("After initialization reversible is : ", rev)

! Retrieve the value of the reversible scalar
 realvalue := getval(rev)
 writeln("Value of the reversible is ", realvalue)

! Save current state of constraint system
 cp_save_state

! Set the value of the reversible to 5
 setval(rev, 5) 
 writeln("Before state restoration value of the reversible is ", getval(rev))

! Restore the saved system state
 cp_restore_state

 writeln("After state restoration reversible is : ", rev)

end-model