BFS implemented in CoffeeScript

bfs.coffee

# G = [vertices]
# vertex = {
#   adjacency_list: [vertex_ids]
#   color: one of ["WHITE", "GRAY", "BLACK"]
#   parent: vertex
#   d: depth
# }

module.exports =
  test: ->
    u0 = {adjacency_list: [1,2]}
    u1 = {adjacency_list: [0]}
    u2 = {adjacency_list: [0,3,4]}
    u3 = {adjacency_list: [2]}
    u4 = {adjacency_list: [2]}
    g = [u0, u1, u2, u3, u4]
    return module.exports.BFS g, u0
  ###
    u0
   /  \
  u1  u2
     / \
    u3 u4
  ###
  BFS: (G, s) ->
    for u in G
      u.color = "WHITE"
      u.d = Infinity
      u.parent = undefined
    s.color = "GRAY"
    s.d = 0
    q = []
    q.push s
    while q.length
      u = q.shift()
      # for each neighbor v of u
      for v_id in u.adjacency_list
        v = G[v_id]
        if v.color == "WHITE"
          v.color = "GRAY"
          v.d = u.d + 1
          v.parent = u
          q.push v
      u.color = "BLACK"
    return G