ometa ClientURIParser{
    word = (letter|``-''|``_'')+:l                                                 -> l.join(''),

    dgit = ^digit:d                                                                -> d.digitValue(),
    nmbr = nmbr:n dgit:d                                                           -> (n * 10 + d)
           | dgit,

    part = (letter|digit|``-''|``_'')+:l                                     -> l.join(''),                       
    parm = part:t (``.'' word:o -> o| -> {f=t;t=[];f}):f
                  (``='' ->`eq|``!=''->`ne|``~'' ->`lk):o part:v ``;''?            -> [o,t,f,v],
    
    imod = ``del'' | ``add'' | ``view'' | ``edit''                                 ,
    cmod = ``del'' | ``filt'' | ``sort''                                           ,
   
    iact = (``*'' imod:a (``:'' parm+ | -> []):p -> [a].concat(p))+ | -> []        ,
    cact = (``*'' cmod:a (``:'' parm+ | -> []):p -> [a].concat(p))+ | -> []        ,
    
    cole = part:t              cact:s  -> [[t]].concat([[`mod].concat(s)]),
    
    inst = part:t ``.'' word:f iact:s  -> [[t,f]].concat([[`mod].concat([[`filt, [`eq, [], `name, f]]]).concat(s)]),
    inst = part:t ``.'' nmbr:f iact:s  -> [[t,f]].concat([[`mod].concat([[`filt, [`eq, [], `id, f]]]).concat(s)]),
    inst = part:t              iact:s  -> [[t]].concat([[`mod].concat(s)]),

    frbd = (``/''? frag:f -> [f]
           |``/''? ``('' (frag:g ``,''? -> g)+:r ``)'' -> r
           |``/''? -> []):f &(end|``/''|``)''|``,'') -> f,

    frag = cole:w frbd:f                 -> [`col].concat(w.concat(f))
         | inst:w frbd:f                 -> [`ins].concat(w.concat(f)),
   
    expr = ``#!/'' (frag:f end -> f):f                                            -> [`uri, f]
         | ``'' -> []
}

uri0 = '#!/'
uri1 = '#!/data/course'
uri2 = '#!/data/course/course*add/'
//uri3 = '#!/data/course/course*del:name=b*del:name=d/'
uri3 = '#!/data/course/(course.1*del,course.math*del)'
//uri4 = '#!/data/course/course*del:name=b;id=c*del:name=d/'
//uri5 = '#!/data/(course/course*del:name=b;id=c*del:name=d,student)'
//uri6 = '#!/data/(course/course*del:name=b;id=c*del:name=d,student/student~is_registered_for~course)'
uri6 = '#!/data/(course/course.4*del,student/student~is_registered_for~course)'
uri7 = '#!/data/student.John'
uri8 = '#!/data/student.134'
//uri9 = '#!/data/(course/course*del:name=b;id=c*del:name=d,student.John/student~is_registered_for~course)'
uri9 = '#!/data/(course/course.4*del,student.John/student~is_registered_for~course)'
//uriA = '#!/data/(course/course*del:name=b;id=c*del:name=d,student.John/student~is_registered_for~course*filt:course.id=19)'
//uriB = '#!/data/(course*del:name=b;id=c*del:name=d,student.John*edit:name=Nick/student~is_registered_for~course*filt:course.id=19)'
uriC = '#!/data/student.134*del'
uriD = '#!/data'
uriE = '#!/data/(course/(course.1*del,course.math*del),student)'
uriF = '#!/data/(course/(course.provID1*del,course.math*del),student)'
uri11 = ''

//Converts a tree to a nested list.

ometa Prettify {
//  elem = [{this.d++} (string|elem|number)*:e {s=this.s(this.d--)}] -> ('['+e.join(',\n'+s+'  ')+'\n'+s+']')
  elem = [{this.d++} (string|elem|number)*:e {s=this.s(this.d--)}] -> ('['+e.join(',\n'+s)+']')
}

Prettify.d = 1
Prettify.s = function(d){a=' ';for(var i=0;i<d;i++){a+='  '};return a}

ometa ClientURIUnparser{
      word = [(letter|``-''|``_''|``~'')+:l]                                        -> l.join(''),
      nmbr = number,

     trans = [:t apply(t):a] -> a,
       uri   trans:t         -> ('#!/' + t),

      name = [word:w nmbr:n] -> (w + '.' + n),
      name = [word:w word:o] -> (w + '.' + o),
      name = [word:w]        -> (w),
       
       col = name:n mod:m trans:t trans+:r {t=[t].concat(r)} -> (n + m + '/(' + t.join(',') + ')'),
       col = name:n mod:m trans:t                          -> (n + m + '/' + t),
       col = name:n mod:m                                  -> (n + m),

       ins = name:n mod:m trans:t trans+:r {t=[t].concat(r)} -> (n + m + '/(' + t.join(',') + ')'),
       ins = name:n mod:m trans:t                          -> (n + m + '/' + t),
       ins = name:n mod:m                                  -> (n + m),

       mod = ['mod' actn+:a] -> a.join('')
           | ['mod']         -> '',

      actn = (add|filt|del|edit),
       add = ['add']          -> '*add',
       del = ['del']          -> '*del',
      edit = ['edit']         -> '*edit',

      filt = ['filt' eqi:o]   -> '',
      filt = ['filt' op*:o]   -> ('*filt:' + o),

        op = eq|ne|lk,

       eqi = ['eq' ([]|word) 'id'   nmbr]        -> '',
       eqi = ['eq' ([]|word) 'name' word]        -> '',        
        eq = ['eq' ([]|word) word   (word|nmbr)],

        ne = ['ne' ([]|word) word   (word|nmbr)],
        lk = ['lk' ([]|word) word   (word|nmbr)]
}

tree = ClientURIParser.matchAll(uri11,'expr')

//tree = ClientURIUnparser.match(["col",["plane"],["mod"],["ins",["plane",1],["mod",["filt",["eq","plane","id",1]]]],["ins",["plane",2],["mod"]]], 'trans')

//Prettify.match(["col",["pilot"],["mod"],["ins",["pilot",4],["mod",["filt",["eq",[],"id",4]]]],["ins",["pilot"],["mod",["add"]]]],'elem')