LUA Json parser

local json = {}

function skip_delim(str, pos, delim, err_if_missing)
  pos = pos + #str:match('^%s*', pos)
  if str:sub(pos, pos) ~= delim then
    if err_if_missing then
      error('Expected ' .. delim .. ' near position ' .. pos)
    end
    return pos, false
  end
  return pos + 1, true
end

function parse_num_val(str, pos)
  local num_str = str:match('^-?%d+%.?%d*[eE]?[+-]?%d*', pos)
  local val = tonumber(num_str)
  if not val then error('Error parsing number at position ' .. pos .. '.') end
  return val, pos + #num_str
end

function parse_str_val(str, pos, val)
  val = val or ''
  local early_end_error = 'End of input found while parsing string.'
  if pos > #str then error(early_end_error) end
  local c = str:sub(pos, pos)
  if c == '"'  then return val, pos + 1 end
  if c ~= '\\' then return parse_str_val(str, pos + 1, val .. c) end
  -- We must have a \ character.
  local esc_map = {b = '\b', f = '\f', n = '\n', r = '\r', t = '\t'}
  local nextc = str:sub(pos + 1, pos + 1)
  if not nextc then error(early_end_error) end
  return parse_str_val(str, pos + 2, val .. (esc_map[nextc] or nextc))
end

function json.parse(str, pos, end_delim)
  pos = pos or 1
  if pos > #str then error('Reached unexpected end of input.') end
  local pos = pos + #str:match('^%s*', pos)  -- Skip whitespace.
  local first = str:sub(pos, pos)
  if first == '{' then  -- Parse an object.
    local obj, key, delim_found = {}, true, true
    pos = pos + 1
    while true do
      key, pos = json.parse(str, pos, '}')
      if key == nil then return obj, pos end
      if not delim_found then error('Comma missing between object items.') end
      pos = skip_delim(str, pos, ':', true)  -- true -> error if missing.
      obj[key], pos = json.parse(str, pos)
      pos, delim_found = skip_delim(str, pos, ',')
    end
  elseif first == '[' then  -- Parse an array.
    local arr, val, delim_found = {}, true, true
    pos = pos + 1
    while true do
      val, pos = json.parse(str, pos, ']')
      if val == nil then return arr, pos end
      if not delim_found then error('Comma missing between array items.') end
      arr[#arr + 1] = val
      pos, delim_found = skip_delim(str, pos, ',')
    end
  elseif first == '"' then  -- Parse a string.
    return parse_str_val(str, pos + 1)
  elseif first == '-' or first:match('%d') then  -- Parse a number.
    return parse_num_val(str, pos)
  elseif first == end_delim then  -- End of an object or array.
    return nil, pos + 1
  else  -- Parse true, false, or null.
    local literals = {['true'] = true, ['false'] = false, ['null'] = json.null}
    for lit_str, lit_val in pairs(literals) do
      local lit_end = pos + #lit_str - 1
      if str:sub(pos, lit_end) == lit_str then return lit_val, lit_end + 1 end
    end
    local pos_info_str = 'position ' .. pos .. ': ' .. str:sub(pos, pos + 10)
    error('Invalid json syntax starting at ' .. pos_info_str)
  end
end

local strJson = '{[{"name":"John", "age":31, "city":"New York"}, {"name":"Rud", "age":58, "city":"Fortaleza"} ]}'

local tableAll = json.parse(strJson,2)

for k, tableItem in pairs(tableAll) do
  print(k, tableItem)
  for k, v in pairs(tableItem) do
      print(k, v)
    end
end