--[[ Expression Language, Utilities Module
     CSci 450: Organization of Programming Languages, Fall 2016
     H. Conrad Cunningham, Professor
     Computer and Information Science
     University of Mississippi

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2016-09-13: Separated from Assignment #1 code, KILT printTree added

These functions are used for output and error messages.

Public display functions:        treeConcat, printTree
Public error/debugging function: show_data

--]]

-- Function "treeConcat" takes a recursive list of lists in "array"
-- argument "t" and returns the corresponding parenthesized traversal
-- string.  A list is stored in the low positive integer indices of an
-- array-style Lua table. This assumes the structure is acyclic.

local function treeConcat(t)
   if type(t) ~= "table" then return tostring(t) end
   local res = {}
   for i = 1, #t do
      res[i] = treeConcat(t[i])
   end
   return "(" .. table.concat(res," ") .. ")"
end

-- Procedure "printTree" prints the corresponding parenthesized
-- traversal string for its argument "t".

local function printTree(t)
   print(treeConcat(t))
end

-- Function "show_data" converts raw Lua data structures to strings to
-- assist in debugging and testing. This assumes the structure is
-- acyclic. 

local function show_data(d)
   if type(d) == "table" then
      local res = {}
      for k,v in pairs(d) do
         res[#res+1] = "[" .. show_data(k) .. "] = " .. show_data(v)
       end
      return "(" .. table.concat(res, ", ") .. ")"
   else
      return tostring(d)
   end
end

-- MODULE EXPORT LIST

return {
   treeConcat  = treeConcat,
   printTree   = printTree,
   show_data   = show_data
}