# PCASTLI version 1.5

# this function generates functions that displays alternatively n results
toggle_gen = function(n)
{
   if (n <= 0) return(copytree(`function() {}'.childset[0]))

   if (n == 1) return(copytree(`function() 1'.childset[0]))

   a = function()
   {
      1
      b = parent.parent.childset[0]
      print(value(b))

      # value substitution
      if (value(b) == 1)
      {
         *b = `2'
      }
      else
      {
         *b = `1'
      }
      {}
   }

   # to have a new function returned at each toggle_gen call
   a = copytree(a)

   else_pt = a.childset[1].childset[3].childset[2]

   for (i = 2; i < n; i++)
   {
      new_stmt = `if (value(b) == 1)
      {
         *b = `2'
      }
      else
      {
         *b = `1'
      }'.childset[0]

      # localization of the first 1 in new_stmt
      # with no ';', the interpreter will take the '*' as the binary operator
      num1 = new_stmt.childset[0].childset[1];
      *num1 = tonode(i)

      # localization of the 2 in new_stmt
      num2 = new_stmt.childset[1].childset[0].childset[1].childset[0];
      *num2 = tonode(i + 1)

      else_pt = (*else_pt = new_stmt)
      else_pt = else_pt.childset[2]
   }

   a
}


toggle_3 = toggle_gen(3)
for(i = 0; i < 5; i++) toggle_3()

toggle_4 = toggle_gen(4)
for(i = 0; i < 6; i++) toggle_4()

toggle_5 = toggle_gen(5)
for(i = 0; i < 7; i++) toggle_5()