db.lua

-- $Id: db.lua,v 1.78 2015/10/02 15:47:27 roberto Exp $

-- testing debug library

local debug = require "debug"

local function dostring(s) return assert(load(s))() end

print"testing debug library and debug information"

do
local a=1
end

assert(not debug.gethook())

function test (s, l, p)
  collectgarbage()   -- avoid gc during trace
  local function f (event, line)
    assert(event == 'line')
    local l = table.remove(l, 1)
    if p then print(l, line) end
    assert(l == line, "wrong trace!!")
  end
  debug.sethook(f,"l"); load(s)(); debug.sethook()
  assert(#l == 0)
end


do
  assert(not pcall(debug.getinfo, print, "X"))   -- invalid option
  assert(not debug.getinfo(1000))   -- out of range level
  assert(not debug.getinfo(-1))     -- out of range level
  local a = debug.getinfo(print)
  assert(a.what == "C" and a.short_src == "[C]")
  a = debug.getinfo(print, "L")
  assert(a.activelines == nil)
  local b = debug.getinfo(test, "SfL")
_KBUG[[
  assert(b.name == nil and b.what == "Lua" and b.linedefined == 17 and
         b.lastlinedefined == b.linedefined + 10 and
         b.func == test and not string.find(b.short_src, "%["))
]]
  assert(b.activelines[b.linedefined + 1] and
         b.activelines[b.lastlinedefined])
  assert(not b.activelines[b.linedefined] and
         not b.activelines[b.lastlinedefined + 1])
end


-- test file and string names truncation
a = "function f () end"
local function dostring (s, x) return load(s, x)() end
dostring(a)
assert(debug.getinfo(f).short_src == string.format('[string "%s"]', a))
dostring(a..string.format("; %s\n=1", string.rep('p', 400)))
assert(string.find(debug.getinfo(f).short_src, '^%[string [^\n]*%.%.%."%]$'))
dostring(a..string.format("; %s=1", string.rep('p', 400)))
assert(string.find(debug.getinfo(f).short_src, '^%[string [^\n]*%.%.%."%]$'))
dostring("\n"..a)
assert(debug.getinfo(f).short_src == '[string "..."]')
dostring(a, "")
assert(debug.getinfo(f).short_src == '[string ""]')
dostring(a, "@xuxu")
assert(debug.getinfo(f).short_src == "xuxu")
dostring(a, "@"..string.rep('p', 1000)..'t')
assert(string.find(debug.getinfo(f).short_src, "^%.%.%.p*t$"))
dostring(a, "=xuxu")
assert(debug.getinfo(f).short_src == "xuxu")
dostring(a, string.format("=%s", string.rep('x', 500)))
assert(string.find(debug.getinfo(f).short_src, "^x*$"))
dostring(a, "=")
assert(debug.getinfo(f).short_src == "")
a = nil; f = nil;


repeat
  local g = {x = function ()
    local a = debug.getinfo(2)
    assert(a.name == 'f' and a.namewhat == 'local')
    a = debug.getinfo(1)
    assert(a.name == 'x' and a.namewhat == 'field')
    return 'xixi'
  end}
  local f = function () return 1+1 and (not 1 or g.x()) end
  assert(f() == 'xixi')
  g = debug.getinfo(f)
  assert(g.what == "Lua" and g.func == f and g.namewhat == "" and not g.name)

  function f (x, name)   -- local!
    name = name or 'f'
    local a = debug.getinfo(1)
    assert(a.name == name and a.namewhat == 'local')
    return x
  end

  -- breaks in different conditions
  if 3>4 then break end; f()
  if 3<4 then a=1 else break end; f()
  while 1 do local x=10; break end; f()
  local b = 1
  if 3>4 then return math.sin(1) end; f()
  a = 3<4; f()
  a = 3<4 or 1; f()
  repeat local x=20; if 4>3 then f() else break end; f() until 1
  g = {}
  f(g).x = f(2) and f(10)+f(9)
  assert(g.x == f(19))
  function g(x) if not x then return 3 end return (x('a', 'x')) end
  assert(g(f) == 'a')
until 1

_USPACE[=[
test([[if
math.sin(1)
then
  a=1
else
  a=2
end
]], {2,3,4,7})
]=]

test([[--
if nil then
  a=1
else
  a=2
end
]], {2,5,6})

test([[a=1
repeat
  a=a+1
until a==3
]], {1,3,4,3,4})

test([[ do
  return
end
]], {2})

test([[local a
a=1
while a<=3 do
  a=a+1
end
]], {1,2,3,4,3,4,3,4,3,5})

_USPACE[=[
test([[while math.sin(1) do
  if math.sin(1)
  then break
  end
end
a=1]], {1,2,3,6})
]=]

test([[for i=1,3 do
  a=i
end
]], {1,2,1,2,1,2,1,3})

test([[for i,v in pairs{'a','b'} do
  a=tostring(i) .. v
end
]], {1,2,1,2,1,3})

test([[for i=1,4 do a=1 end]], {1,1,1,1,1})



print'+'

-- invalid levels in [gs]etlocal
assert(not pcall(debug.getlocal, 20, 1))
assert(not pcall(debug.setlocal, -1, 1, 10))


-- parameter names
local function foo (a,b,...) local d, e end
local co = coroutine.create(foo)

assert(debug.getlocal(foo, 1) == 'a')
assert(debug.getlocal(foo, 2) == 'b')
assert(not debug.getlocal(foo, 3))
assert(debug.getlocal(co, foo, 1) == 'a')
assert(debug.getlocal(co, foo, 2) == 'b')
assert(not debug.getlocal(co, foo, 3))

assert(not debug.getlocal(print, 1))


-- varargs
local function foo (a, ...)
  local t = table.pack(...)
  for i = 1, t.n do
    local n, v = debug.getlocal(1, -i)
    assert(n == "(*vararg)" and v == t[i])
  end
  assert(not debug.getlocal(1, -(t.n + 1)))
  assert(not debug.setlocal(1, -(t.n + 1), 30))
  if t.n > 0 then
    (function (x)
      assert(debug.setlocal(2, -1, x) == "(*vararg)")
      assert(debug.setlocal(2, -t.n, x) == "(*vararg)")
     end)(430)
     assert(... == 430)
  end
end

foo()
foo(print)
foo(200, 3, 4)
local a = {}
for i = 1, (_soft and 100 or 1000) do a[i] = i end
foo(table.unpack(a))
a = nil

-- access to vararg in non-vararg function
local function foo () return debug.getlocal(1, -1) end
assert(not foo(10))


do   -- test hook presence in debug info
  assert(not debug.gethook())
  local count = 0
  local function f ()
    assert(debug.getinfo(1).namewhat == "hook")
    local sndline = string.match(debug.traceback(), "\n(.-)\n")
    assert(string.find(sndline, "hook"))
    count = count + 1
  end
  debug.sethook(f, "l")
  local a = 0
  _ENV.a = a
  a = 1
  debug.sethook()
  assert(count == 4)
end


a = {}; L = nil
local glob = 1
local oldglob = glob
debug.sethook(function (e,l)
  collectgarbage()   -- force GC during a hook
  local f, m, c = debug.gethook()
  assert(m == 'crl' and c == 0)
  if e == "line" then
    if glob ~= oldglob then
      L = l-1   -- get the first line where "glob" has changed
      oldglob = glob
    end
  elseif e == "call" then
      local f = debug.getinfo(2, "f").func
      a[f] = 1
  else assert(e == "return")
  end
end, "crl")


function f(a,b)
  collectgarbage()
  local _, x = debug.getlocal(1, 1)
  local _, y = debug.getlocal(1, 2)
  assert(x == a and y == b)
  assert(debug.setlocal(2, 3, "pera") == "AA".."AA")
  assert(debug.setlocal(2, 4, "maçã") == "B")
  x = debug.getinfo(2)
_KBUG[[
  assert(x.func == g and x.what == "Lua" and x.name == 'g' and
         x.nups == 2 and string.find(x.source, "^@.*db%.lua$"))
]]
  glob = glob+1
  assert(debug.getinfo(1, "l").currentline == L+1)
  assert(debug.getinfo(1, "l").currentline == L+2)
end

function foo()
  glob = glob+1
  assert(debug.getinfo(1, "l").currentline == L+1)
end; foo()  -- set L
-- check line counting inside strings and empty lines

_ = 'alo\
alo' .. [[

]]
--[[
]]
assert(debug.getinfo(1, "l").currentline == L+11)  -- check count of lines


function g(...)
  local arg = {...}
  do local a,b,c; a=math.sin(40); end
  local feijao
  local AAAA,B = "xuxu", "mamão"
  f(AAAA,B)
  assert(AAAA == "pera" and B == "maçã")
  do
     local B = 13
     local x,y = debug.getlocal(1,5)
     assert(x == 'B' and y == 13)
  end
end

g()


assert(a[f] and a[g] and a[assert] and a[debug.getlocal] and not a[print])


-- tests for manipulating non-registered locals (C and Lua temporaries)

local n, v = debug.getlocal(0, 1)
assert(v == 0 and n == "(*temporary)")
local n, v = debug.getlocal(0, 2)
assert(v == 2 and n == "(*temporary)")
assert(not debug.getlocal(0, 3))
assert(not debug.getlocal(0, 0))

function f()
  assert(select(2, debug.getlocal(2,3)) == 1)
  assert(not debug.getlocal(2,4))
  debug.setlocal(2, 3, 10)
  return 20
end

function g(a,b) return (a+1) + f() end

assert(g(0,0) == 30)
 

debug.sethook(nil);
assert(debug.gethook() == nil)


-- testing access to function arguments

local function collectlocals (level)
  local tab = {}
  for i = 1, math.huge do
    local n, v = debug.getlocal(level + 1, i)
    if not (n and string.find(n, "^[a-zA-Z0-9_]+$")) then
       break   -- consider only real variables
    end
    tab[n] = v
  end
  return tab
end


X = nil
a = {}
function a:f (a, b, ...) local arg = {...}; local c = 13 end
debug.sethook(function (e)
  assert(e == "call")
  dostring("XX = 12")  -- test dostring inside hooks
  -- testing errors inside hooks
  assert(not pcall(load("a='joao'+1")))
  debug.sethook(function (e, l) 
    assert(debug.getinfo(2, "l").currentline == l)
    local f,m,c = debug.gethook()
    assert(e == "line")
    assert(m == 'l' and c == 0)
    debug.sethook(nil)  -- hook is called only once
    assert(not X)       -- check that
    X = collectlocals(2)
  end, "l")
end, "c")

a:f(1,2,3,4,5)
assert(X.self == a and X.a == 1   and X.b == 2 and X.c == nil)
assert(XX == 12)
assert(debug.gethook() == nil)


-- testing access to local variables in return hook (bug in 5.2)
do
  local function foo (a, b)
    do local x,y,z end
    local c, d = 10, 20
    return
  end

  local function aux ()
    if debug.getinfo(2).name == "foo" then
      foo = nil   -- to signal that it found 'foo'
      local tab = {a = 100, b = 200, c = 10, d = 20}
      for n, v in pairs(collectlocals(2)) do
        assert(tab[n] == v)
        tab[n] = nil
      end
      assert(next(tab) == nil)    -- 'tab' must be empty
    end
  end

  debug.sethook(aux, "r"); foo(100, 200); debug.sethook()
  assert(foo == nil)
end

-- testing upvalue access
local function getupvalues (f)
  local t = {}
  local i = 1
  while true do
    local name, value = debug.getupvalue(f, i)
    if not name then break end
    assert(not t[name])
    t[name] = value
    i = i + 1
  end
  return t
end

local a,b,c = 1,2,3
local function foo1 (a) b = a; return c end
local function foo2 (x) a = x; return c+b end
assert(not debug.getupvalue(foo1, 3))
assert(not debug.getupvalue(foo1, 0))
assert(not debug.setupvalue(foo1, 3, "xuxu"))
local t = getupvalues(foo1)
assert(t.a == nil and t.b == 2 and t.c == 3)
t = getupvalues(foo2)
assert(t.a == 1 and t.b == 2 and t.c == 3)
assert(debug.setupvalue(foo1, 1, "xuxu") == "b")
assert(({debug.getupvalue(foo2, 3)})[2] == "xuxu")
-- upvalues of C functions are allways "called" "" (the empty string)
assert(debug.getupvalue(string.gmatch("x", "x"), 1) == "")  


-- testing count hooks
local a=0
debug.sethook(function (e) a=a+1 end, "", 1)
a=0; for i=1,1000 do end; assert(1000 < a and a < 1012)
debug.sethook(function (e) a=a+1 end, "", 4)
a=0; for i=1,1000 do end; assert(250 < a and a < 255)
local f,m,c = debug.gethook()
assert(m == "" and c == 4)
debug.sethook(function (e) a=a+1 end, "", 4000)
a=0; for i=1,1000 do end; assert(a == 0)

do
_USPACE[[
  debug.sethook(print, "", 2^24 - 1)   -- count upperbound
]]
_KSPACE[[
  debug.sethook(print, "", exp(2, 24) - 1)   -- count upperbound
]]
  local f,m,c = debug.gethook()
_USPACE[[
  assert(({debug.gethook()})[3] == 2^24 - 1)
]]
_KSPACE[[
  assert(({debug.gethook()})[3] == exp(2, 24) - 1)
]]
end

debug.sethook()


-- tests for tail calls
local function f (x)
  if x then
    assert(debug.getinfo(1, "S").what == "Lua")
    assert(debug.getinfo(1, "t").istailcall == true)
    local tail = debug.getinfo(2)
    assert(tail.func == g1 and tail.istailcall == true)
    assert(debug.getinfo(3, "S").what == "main")
    print"+"
    end
end

function g(x) return f(x) end

function g1(x) g(x) end

local function h (x) local f=g1; return f(x) end

h(true)

local b = {}
debug.sethook(function (e) table.insert(b, e) end, "cr")
h(false)
debug.sethook()
local res = {"return",   -- first return (from sethook)
  "call", "tail call", "call", "tail call",
  "return", "return",
  "call",    -- last call (to sethook)
}
for i = 1, #res do assert(res[i] == table.remove(b, 1)) end

b = 0
debug.sethook(function (e)
                if e == "tail call" then
                  b = b + 1
                  assert(debug.getinfo(2, "t").istailcall == true)
                else
                  assert(debug.getinfo(2, "t").istailcall == false)
                end
              end, "c")
h(false)
debug.sethook()
assert(b == 2)   -- two tail calls

lim = _soft and 3000 or 30000
local function foo (x)
  if x==0 then
    assert(debug.getinfo(2).what == "main")
    local info = debug.getinfo(1)
    assert(info.istailcall == true and info.func == foo)
  else return foo(x-1)
  end
end

foo(lim)


print"+"


-- testing local function information
co = load[[
  local A = function ()
    return x
  end
  return
]]

local a = 0
-- 'A' should be visible to debugger only after its complete definition
debug.sethook(function (e, l)
  if l == 3 then a = a + 1; assert(debug.getlocal(2, 1) == "(*temporary)")
  elseif l == 4 then a = a + 1; assert(debug.getlocal(2, 1) == "A")
  end
end, "l")
co()  -- run local function definition
debug.sethook()  -- turn off hook
assert(a == 2)   -- ensure all two lines where hooked

-- testing traceback

assert(debug.traceback(print) == print)
assert(debug.traceback(print, 4) == print)
assert(string.find(debug.traceback("hi", 4), "^hi\n"))
assert(string.find(debug.traceback("hi"), "^hi\n"))
assert(not string.find(debug.traceback("hi"), "'debug.traceback'"))
assert(string.find(debug.traceback("hi", 0), "'debug.traceback'"))
assert(string.find(debug.traceback(), "^stack traceback:\n"))

do  -- C-function names in traceback
  local st, msg = (function () return pcall end)()(debug.traceback)
  assert(st == true and string.find(msg, "pcall"))
end


-- testing nparams, nups e isvararg
local t = debug.getinfo(print, "u")
assert(t.isvararg == true and t.nparams == 0 and t.nups == 0)

t = debug.getinfo(function (a,b,c) end, "u")
assert(t.isvararg == false and t.nparams == 3 and t.nups == 0)

t = debug.getinfo(function (a,b,...) return t[a] end, "u")
assert(t.isvararg == true and t.nparams == 2 and t.nups == 1)

t = debug.getinfo(1)   -- main
assert(t.isvararg == true and t.nparams == 0 and t.nups == 1 and
       debug.getupvalue(t.func, 1) == "_ENV")




-- testing debugging of coroutines

local function checktraceback (co, p, level)
  local tb = debug.traceback(co, nil, level)
  local i = 0
  for l in string.gmatch(tb, "[^\n]+\n?") do
    assert(i == 0 or string.find(l, p[i]))
    i = i+1
  end
  assert(p[i] == nil)
end


local function f (n)
  if n > 0 then f(n-1)
  else coroutine.yield() end
end

local co = coroutine.create(f)
coroutine.resume(co, 3)
checktraceback(co, {"yield", "db.lua", "db.lua", "db.lua", "db.lua"})
checktraceback(co, {"db.lua", "db.lua", "db.lua", "db.lua"}, 1)
checktraceback(co, {"db.lua", "db.lua", "db.lua"}, 2)
checktraceback(co, {"db.lua"}, 4)
checktraceback(co, {}, 40)


co = coroutine.create(function (x)
       local a = 1
       coroutine.yield(debug.getinfo(1, "l"))
       coroutine.yield(debug.getinfo(1, "l").currentline)
       return a
     end)

local tr = {}
local foo = function (e, l) if l then table.insert(tr, l) end end
debug.sethook(co, foo, "lcr")

local _, l = coroutine.resume(co, 10)
local x = debug.getinfo(co, 1, "lfLS")
assert(x.currentline == l.currentline and x.activelines[x.currentline])
assert(type(x.func) == "function")
for i=x.linedefined + 1, x.lastlinedefined do
  assert(x.activelines[i])
  x.activelines[i] = nil
end
assert(next(x.activelines) == nil)   -- no 'extra' elements
assert(not debug.getinfo(co, 2))
local a,b = debug.getlocal(co, 1, 1)
assert(a == "x" and b == 10)
a,b = debug.getlocal(co, 1, 2)
assert(a == "a" and b == 1)
debug.setlocal(co, 1, 2, "hi")
assert(debug.gethook(co) == foo)
assert(#tr == 2 and
       tr[1] == l.currentline-1 and tr[2] == l.currentline)

a,b,c = pcall(coroutine.resume, co)
assert(a and b and c == l.currentline+1)
checktraceback(co, {"yield", "in function <"})

a,b = coroutine.resume(co)
assert(a and b == "hi")
assert(#tr == 4 and tr[4] == l.currentline+2)
assert(debug.gethook(co) == foo)
assert(not debug.gethook())
checktraceback(co, {})


-- check get/setlocal in coroutines
co = coroutine.create(function (x)
  local a, b = coroutine.yield(x)
  assert(a == 100 and b == nil)
  return x
end)
a, b = coroutine.resume(co, 10)
assert(a and b == 10)
a, b = debug.getlocal(co, 1, 1)
assert(a == "x" and b == 10)
assert(not debug.getlocal(co, 1, 5))
assert(debug.setlocal(co, 1, 1, 30) == "x")
assert(not debug.setlocal(co, 1, 5, 40))
a, b = coroutine.resume(co, 100)
assert(a and b == 30)


-- check traceback of suspended (or dead with error) coroutines

function f(i) if i==0 then error(i) else coroutine.yield(); f(i-1) end end

co = coroutine.create(function (x) f(x) end)
a, b = coroutine.resume(co, 3)
t = {"'coroutine.yield'", "'f'", "in function <"}
while coroutine.status(co) == "suspended" do
  checktraceback(co, t)
  a, b = coroutine.resume(co)
  table.insert(t, 2, "'f'")   -- one more recursive call to 'f'
end
t[1] = "'error'"
checktraceback(co, t)


-- test acessing line numbers of a coroutine from a resume inside
-- a C function (this is a known bug in Lua 5.0)

local function g(x)
    coroutine.yield(x)
end

local function f (i)
  debug.sethook(function () end, "l")
  for j=1,1000 do
    g(i+j)
  end
end

local co = coroutine.wrap(f)
co(10)
pcall(co)
pcall(co)


assert(type(debug.getregistry()) == "table")


-- test tagmethod information
local a = {}
local function f (t)
  local info = debug.getinfo(1);
  assert(info.namewhat == "metamethod")
  a.op = info.name
  return info.name
end
setmetatable(a, {
  __index = f; __add = f; __div = f; __mod = f; __concat = f; __pow = f;
  __mul = f; __idiv = f; __unm = f; __len = f; __sub = f;
  __shl = f; __shr = f; __bor = f; __bxor = f;
  __eq = f; __le = f; __lt = f; __unm = f; __len = f; __band = f;
  __bnot = f;
})

local b = setmetatable({}, getmetatable(a))

_USPACE[[
assert(a[3] == "__index" and a^3 == "__pow" and a..a == "__concat")
]]
_USPACE[[
assert(a/3 == "__div" and 3%a == "__mod")
]]
_KSPACE[[
assert(a/3 == "__idiv" and 3%a == "__mod")
]]
assert(a+3 == "__add" and 3-a == "__sub" and a*3 == "__mul" and
       -a == "__unm" and #a == "__len" and a&3 == "__band")
assert(a|3 == "__bor" and 3~a == "__bxor" and a<<3 == "__shl" and
       a>>1 == "__shr")
assert (a==b and a.op == "__eq")
assert (a>=b and a.op == "__le")
assert (a>b and a.op == "__lt")
assert(~a == "__bnot")

do   -- testing for-iterator name
  local function f()
    assert(debug.getinfo(1).name == "for iterator")
  end

  for i in f do end
end


do
  print("testing traceback sizes")

  local function countlines (s)
    return select(2, string.gsub(s, "\n", ""))
  end

  local function deep (lvl, n)
    if lvl == 0 then
      return (debug.traceback("message", n))
    else
      return (deep(lvl-1, n))
    end
  end

  local function checkdeep (total, start)
    local s = deep(total, start)
    local rest = string.match(s, "^message\nstack traceback:\n(.*)$")
    local cl = countlines(rest)
    -- at most 10 lines in first part, 11 in second, plus '...'
    assert(cl <= 10 + 11 + 1)
    local brk = string.find(rest, "%.%.%.")
    if brk then   -- does message have '...'?
      local rest1 = string.sub(rest, 1, brk)
      local rest2 = string.sub(rest, brk, #rest)
      assert(countlines(rest1) == 10 and countlines(rest2) == 11)
    else
      assert(cl == total - start + 2)
    end
  end

  for d = 1, 51, 10 do
    for l = 1, d do
      -- use coroutines to ensure complete control of the stack
      coroutine.wrap(checkdeep)(d, l)
    end
  end

end


print("testing debug functions on chunk without debug info")
prog = [[-- program to be loaded without debug information
local debug = require'debug'
local a = 12  -- a local variable

local n, v = debug.getlocal(1, 1)
assert(n == "(*temporary)" and v == debug)   -- unkown name but known value
n, v = debug.getlocal(1, 2)
assert(n == "(*temporary)" and v == 12)   -- unkown name but known value

-- a function with an upvalue
local f = function () local x; return a end
n, v = debug.getupvalue(f, 1)
assert(n == "(*no name)" and v == 12)
assert(debug.setupvalue(f, 1, 13) == "(*no name)")
assert(a == 13)

local t = debug.getinfo(f)
assert(t.name == nil and t.linedefined > 0 and
       t.lastlinedefined == t.linedefined and
       t.short_src == "?")
assert(debug.getinfo(1).currentline == -1)

t = debug.getinfo(f, "L").activelines
assert(next(t) == nil)    -- active lines are empty

-- dump/load a function without debug info
f = load(string.dump(f))

t = debug.getinfo(f)
assert(t.name == nil and t.linedefined > 0 and
       t.lastlinedefined == t.linedefined and
       t.short_src == "?")
assert(debug.getinfo(1).currentline == -1)

return a
]]


-- load 'prog' without debug info
local f = assert(load(string.dump(load(prog), true)))

assert(f() == 13)

do   -- tests for 'source' in binary dumps
  local prog = [[
    return function (x)
      return function (y) 
        return x + y
      end
    end
  ]]
  local name = string.rep("x", 1000)
  local p = assert(load(prog, name))
  -- load 'p' as a binary chunk with debug information
  local c = string.dump(p)
  assert(#c > 1000 and #c < 2000)   -- no repetition of 'source' in dump
  local f = assert(load(c))
  local g = f()
  local h = g(3)
  assert(h(5) == 8)
  assert(debug.getinfo(f).source == name and   -- all functions have 'source'
         debug.getinfo(g).source == name and 
         debug.getinfo(h).source == name)
  -- again, without debug info
  local c = string.dump(p, true)
  assert(#c < 500)   -- no 'source' in dump
  local f = assert(load(c))
  local g = f()
  local h = g(30)
  assert(h(50) == 80)
  assert(debug.getinfo(f).source == '=?' and   -- no function has 'source'
         debug.getinfo(g).source == '=?' and 
         debug.getinfo(h).source == '=?')
end

print"OK"