Roundtrip backstep indentation to s-expr json to text formatter, under http://fiddle.jshell.net/uHL8r/26/show/light/

backstep-roundtrip.ls

ind = ->
  out = []
  for line in it / \\n
    # line.replace /[^\s]+( [^\s]+)*/g (w,_,at)->
    line.replace /[^\s]+/g (w,at)-> # actually just iterate
      out.push [at,w]
    #
  out
ren = ->
  cur = 0
  (for [at,w] in it
    ( if cur < at => ""
      else cur=0; "\n"
    )+(
      pad = "\xa0"*(at - cur)
      cur = at + w.length
      pad+w
    )
  )*""
nest = ->
  nes = [[-1,[]]] # list [dep,ele]
  for [at,w] in it ++ [ [-1,[]] ] # outdent all the way
    for [dep,ele] in nes.slice() | dep > at
      nes[1][1].push ele; nes.shift()
    if dep < at
      nes.unshift [at,[]]
    if w != ':'
      nes[0][1].push w
    #
  nes[0][1][0]
noun = (jon,out=[],dep=0)->
  | !jon.map => out ++ [ [dep,jon] ]
  | !jon[1]? => noun jon[0], out, dep
  | jon[0]?.map => noun [":" jon[0],jon[1]], out, dep
  | _ =>
    out.push [dep,jon[0]]
    lim = 0
    unless jon[1].length > 2
      lim = 1
      out = noun jon[1], out, dep+(Math.max jon[0].length+1, 1*(jon.length-2))
    for sub, i in jon | i>lim
      out = noun sub, out, dep+2*(jon.length-1 - i)
    out
  #
p = -> (JSON.stringify it,,2)/" "*\\xa0
parse = -> nest ind it
print = -> ren noun it
rint = ->it # "p rint", geddit?
#
diff = (a,b)->
  if a.length != b.length
    throw Error "Not that kind of diff: a is #{a.length} lines, b is #{b.length}"
  for s,i in a
    if s.replace(/\xa0/g, " ") == b[i]?.replace /\xa0/g " "
      "\xa0 #s"
    else """
         - #s
         + #{b[i]}
         """
    #
  |> (*\\n)
#
here = $ \:focus .0.innerText
here .= replace /[ ]/g \\xa0
diff (("\n"+here)/\\n), ((print parse here)+"\n")/\\n
("\n"+here) == (print parse here)+"\n"
#@indenter = {ind,ren,nest,noun,parse,print}