Improved compatibility with old coroutines

src/coroutine/make.lua

@@ -7,7 +7,24 @@ local status      = coroutine.status
 local wrap        = coroutine.wrap
 local yield       = coroutine.yield
 
-return function (tag)
+local depth = 1
+local maxdepth = math.huge -- Change this to change max coroutine depth --
+
+local function prep(f) -- Prepare function environment --
+  if getfenv and setfenv and setmetatable then
+    local tbo = getfenv(f)
+    local tba = setmetatable({coroutine = coronest()},{__index = tbo, __newindex = tbo})
+    setfenv(f,tba)
+  elseif debug and debug.getupvalue and debug.setupvalue and setmetatable then
+    local tbo = debug.getupvalue(f,1)
+    local tba = setmetatable({coroutine = coronest()},{__index = tbo, __newindex = tbo})
+    debug.setupvalue(f,1,tba)
+  end
+  return f
+end
+
+local coronest
+coronest = function (tag)
   local coroutine = {
     isyieldable = isyieldable,
     running     = running,
@@ -33,17 +50,23 @@ return function (tag)
     end
   end
 
-  function coroutine.create (f)
+  function coroutine.create (fa)
+    local f = prep(fa)
     return create (function (...)
       return tag, f (...)
     end)
   end
 
   function coroutine.resume (co, ...)
+    if depth >= maxdepth then
+      return false, "Maximum coroutine depth ".. maxdepth .." reached!"
+    end
+    depth = depth + 1
     return for_resume (co, resume (co, ...))
   end
 
-  function coroutine.wrap (f)
+  function coroutine.wrap (fa)
+    local f = prep(fa)
     local co = wrap (function (...)
       return tag, f (...)
     end)
@@ -53,8 +76,10 @@ return function (tag)
   end
 
   function coroutine.yield (...)
+    depth = depth - 1
     return yield (tag, ...)
   end
 
   return coroutine
 end
+return coronest