minetest-scripts/tokenize.lua

-- things between spaces, () separate depths
local tokenize
tokenize = function(str)
  if not str then return nil end
  local ast = {}
  local open = str:find("(", 0, true) or math.huge
  local close = str:find(")", 0, true) or math.huge
  local space = str:find(" ", 0, true) or math.huge
  local ret
  if open < close and open < space then
    -- tokenize what came before (call on substring, unpack here), call tokenize on what comes after
    ret = tokenize(str:sub(1, open - 1))
    if ret then
      while #ret > 0 do
        table.insert(ast, table.remove(ret, 1))
      end
    end
    ret, str = tokenize(str:sub(open + 1))
    if ret and #ret > 0 then
      table.insert(ast, ret)
    end
    ret = tokenize(str)
    if ret then
      while #ret > 0 do
        table.insert(ast, table.remove(ret, 1))
      end
    end
    return ast
  elseif close < open and close < space then
    return ast, str:sub(close + 1)
  elseif space < open and space < close then
    ret = str:sub(1, space - 1)
    if ret and #ret > 0 then
      table.insert(ast, ret)
    end
    ret, str = tokenize(str:sub(space + 1))
    if ret and #ret > 0 then
      table.insert(ast, ret)
    end
    ret = tokenize(str)
    if ret then
      while #ret > 0 do
        table.insert(ast, table.remove(ret, 1))
      end
    end
    return ast
  else
    table.insert(ast, str:sub(1, space - 1))
    return ast
  end
end

local ptable
ptable = function(tab, depth)
  local str = ""
  depth = depth or 0
  if "table" == type(tab) then
    for k,v in pairs(tab) do
      str = str .. string.rep(" ", depth) .. ptable(k, depth) .. "\n"
      str = str .. string.rep(" ", depth) .. ptable(v, depth + 1) .. "\n"
    end
  else
    return tostring(tab)
  end
  return str
end

local a = "(echo (: 'value' ($ name)))"
ast = tokenize(a)
print(ptable(ast))