/* 

  Global constraint elements in Picat.

  From Global Constraint Catalogue
  http://www.emn.fr/x-info/sdemasse/gccat/Celements.html
  """
  Constraint

      elements(ITEMS,TABLE)

  Restriction(s)
      required(ITEMS,[index,value])
      ITEMS.index>=1
      ITEMS.index<=|TABLE|
      required(TABLE,[index,value])
      TABLE.index>=1
      TABLE.index<=|TABLE|
      distinct(TABLE,index)
  Purpose

  All the items of ITEMS should be equal to one of the entries of the 
  table TABLE.

  Example
      (
      <index-4 value-9, index-1 value-6>,
      <
          index-1 value-6,
          index-2 value-9,
          index-3 value-2,
          index-4 value-9
      >
      )

  The elements constraint holds since each item of its first argument ITEMS 
  corresponds to an item of the TABLE collection: the first item 
  <index-4 value-9> of ITEMS corresponds to the fourth item of TABLE, while 
  the second item <index-1 value-6> of ITEMS corresponds to the first 
  item of TABLE.

  Usage

  Used for replacing several element constraints sharing exactly the same table 
  by one single constraint.
  """


  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/

import cp.


main => go.

go ?=>
  N = 4, % length of table
  M = 2,% length of items
  
  ElementTable = new_list(N),
  ElementTable :: 1..9,
  Items = new_list(M),
  Items :: 1..9,

  ElementTable = [6,9,2,9],
  Items = [9,6],
  % Items = [9,5], % false
  
  elements(Items, ElementTable),

  Vars = ElementTable ++ Items,
  solve(Vars),

  println(elementTable=ElementTable),
  println(items=Items),
  nl,

  fail,

  nl.

go => true.


elements(Items, ElementTable) =>
  foreach(I in 1..Items.len) 
    sum([Items[I] #= ElementTable[J] : J in 1..ElementTable.len]) #>= 1
  end.