-{ extension 'match' }

require 'walk.id'

ast = +{ block:
         y = type(1)
         function foo(x)
            local type = 'number'
            assert(x==type or not x)
         end
         foo(x) }

disp = |msg,ast| printf("\n%s:\n%s", msg, table.tostring(ast, 80, 'nohash'))
disp('initial term', ast)

require'autotable'

do -- Make globals explicit:
   local ast = table.deep_copy(ast)
   local cfg = { id = { } }
   function cfg.id.free(i) 
      i <- `Index{ `Id '_G', `String{i[1]} } 
      return 'break'
   end   
   walk_id.block(cfg, ast)
   disp('Globals made explicit', ast)
end


do -- Alpha rename local vars:
   local ast = table.deep_copy(ast)
   local cfg = { id = { } }
   local translations = autotable()
   function cfg.id.bound (id, binder) 
      local tmp = translations[id[1]]
      if not tmp then
         printf("new tmp for name %s", id[1])
         tmp = { }
         translations[id[i]] = tmp
      end
      local new_name = tmp[binder]
      if not new_name then
         printf("new name for name %s binder %s", id[1], tostring(binder))
         new_name = mlp.gensym('_local_'..id[1])
         
         tmp[binder] = new_name
      end
      id[1] = new_name
   end
   walk_id.block(cfg, ast)
   disp('Local alpha-renamed', ast)
end


--[=[


local varlist_mt = { __index = function (self, key) 
                                  local x={ }; self[key] = x; return x 
                               end }
local bound_vars = setmetatable({ }, varlist_mt)
local free_vars  = setmetatable({ }, varlist_mt)

cfg = { 
   id = { 
      bound = |x, binder| table.insert(bound_vars[binder], x),
      free  = |x|         table.insert(free_vars[x[1]], x) } }

walk_id.block(cfg, x)

-- Alpha convert bound variables
for binder, occurences in pairs(bound_vars) do
   local new_name = "_LOCAL_"..occurences[1][1]
   local cfg = { binder = function (x) x[1]=new_name; return 'break' end }
   walk.guess(cfg, binder)
   for occ in ivalues(occurences) do occ[1] = new_name end
end

-- Alpha convert free variables
for name, occurences in pairs(free_vars) do
   local new_name = "_GLOBAL_"..occurences[1][1]
   for occ in ivalues(occurences) do occ[1] = new_name end
end   
--]=]

--print "\n\n TERM AFTER PARSING:"
--table.print(x,60,'nohash')