var2node method

Whenever, in a literal, we encounter an atom naming a variable, we invoke method var2node to make sure that this variable is already encoded and to retrieve the corresponding node representation. If this is the first time we encounter this variable , we allocate for it a new integer and create a node representation for it. Further, we also create for all variables that were known sofar (i.e. all variables encoded by integers smaller than the one encoding ).

<Dominance: Solver class, var2node method>=

meth var2node(X Node)
   I = {Dictionary.condGet @var2int X unit}
in 
   if I==unit then 
      I=(counter<-I)+1
   in 
      {FS.include I @vars}
      Node={MakeNode I @vars}
      @var2int.X  := I
      @int2node.I := Node
      for J in 1..(I-1) do 
         @choices.(I*1000+J) := {FD.int 1#4}
      end 
   else Node=@int2node.I end 
end