# Tools and types to handle the "front" set of the HotPath heuristic.
# Last edited on 2021-02-08 19:52:43 by jstolfi 

import front_IMP

#  During the heuristics, if 
#  
#  When a path {ph} is part of a tentative tool-path, 

def get_one(R, rev):
  # Returns a list containing a single element of the filler set {R}
  # that has not been incorporated into the current tentative tool path.
  #
  # Assumes that element that have been incorporated have their field
  # {.htini} set to not a value different from {None}. Returns an empty
  # list if all elements are in the path.
  #
  # If {rev} is false, scans the list in increasing index order, else
  # scans it in the opposite order.
  return front_IMP.get_one(R, rev)

def get_initial_fringe(R):
  # Retuns a list of filler elements of {R} that have not been 
  # incorporated into the current tentative tool path
  # and have no contacts. Returns an empty
  # list if all elements are in the path.
  return front_IMP.get_initial_fringe(R)

def get_initial_all (R):
  # Returns a list (possibly empty) with all filler elements of {R} that are not yet included
  # in the current tentative tool-path.
  return front_IMP.get_initial_all(R)

def add_element(L, el):
  # If the filler element {el} is not in the list {L} and not 
  # in the current tentative tool-path (that is, {el.htini} is {None}),
  # appends {el} to {L} and return {True}, else returns {False}.
  return front_IMP.add_element(L, el)