[Lua] Print table contents recursively and more usefully

0-tprint.lua

-- Original: [Lua] Print table contents recursively https://gist.github.com/hashmal/874792
-- Additional Features:
-- * Safe for any types by tostring(): https://gist.github.com/xytis/5361405
-- * Explicitly indicate empty tables
-- * Avoid extracting already-printed tables to prevent infinite loop for self-referential tables such as _G
-- * Format strings like literals to improve readability and preserve indentation
function tprint(tbl, indent, tprinted)
  indent = indent or 0
  tprinted = tprinted or { [tostring(tbl)] = true }
  local indentstr = string.rep("  ", indent)
  if not next(tbl) then
    print(indentstr .. "(empty)")
  else
    for k, v in pairs(tbl) do
      local vstr = tostring(v)
      local header = string.format("%s[%s] ", indentstr, k)
      if type(v) == "table" then
        if tprinted[vstr] then
          print(header .. vstr .. " (already printed)")
        else
          tprinted[vstr] = true
          print(header .. vstr)
          tprinted = tprint(v, indent + 1, tprinted)
        end
      else
        if type(v) == "string" then
          v = v:gsub("\\", "\\\\"):gsub('"', '\\"')
               :gsub("\n", "\\n"):gsub("\r", "\\r")
               :gsub("\t", "\\t"):gsub("\v", "\\v")
               :gsub("\a", "\\a"):gsub("\b", "\\b"):gsub("\f", "\\f")
          vstr = '"' .. v .. '"'
        end
        print(header .. vstr)
      end
    end
  end
  return tprinted
end

1-example.lua

local tbl = { 42, true, a = "A", c = "C:\\Windows" }
tbl.lines = [[Lorem
ipsum
dolor]]
tbl.empty = {}
tbl.nested = { 100, 200, { 300 } }
tbl.square = function(v) return v * v end
tbl.self = tbl

tprint(tbl)

--[[
[1] 42
[2] true
[self] table: 0x23779f00 (already printed)
[square] function: 0x2376a2d0
[empty] table: 0x2376a338
  (empty)
[nested] table: 0x23766678
  [1] 100
  [2] 200
  [3] table: 0x2376a298
    [1] 300
[lines] "Lorem\nipsum\ndolor"
[c] "C:\\Windows"
[a] "A"
]]--

Article: https://qiita.com/Phroneris/items/32010f074f6c105480da