1 files changed, 325 insertions, 0 deletions

diff --git a/src/compat53/init.lua b/src/compat53/init.lua
new file mode 100644
index 00000000..b5075713
--- /dev/null
+++ b/src/compat53/init.lua
@@ -0,0 +1,325 @@
+local lua_version = _VERSION:sub(-3)
+
+
+if lua_version < "5.3" then
+
+   local _G, pairs, require, select, type =
+         _G, pairs, require, select, type
+   local debug, io = debug, io
+   local unpack = lua_version == "5.1" and unpack or table.unpack
+
+   local M = require("compat53.module")
+
+   -- select the most powerful getmetatable function available
+   local gmt = type(debug) == "table" and debug.getmetatable or
+               getmetatable or function() return false end
+   -- metatable for file objects from Lua's standard io library
+   local file_meta = gmt(io.stdout)
+
+
+   -- detect LuaJIT (including LUAJIT_ENABLE_LUA52COMPAT compilation flag)
+   local is_luajit = (string.dump(function() end) or ""):sub(1, 3) == "\027LJ"
+   local is_luajit52 = is_luajit and
+     #setmetatable({}, { __len = function() return 1 end }) == 1
+
+
+   if type(file_meta) == "table" and type(file_meta.__index) == "table" then
+      local file_mt = require("compat53.file_mt")
+      file_mt.update_file_meta(file_meta, is_luajit52)
+   end -- got a valid metatable for file objects
+
+
+   -- changes for Lua 5.1 only
+   if lua_version == "5.1" then
+
+      -- cache globals
+      local error, pcall, rawset, setmetatable, tostring, xpcall =
+            error, pcall, rawset, setmetatable, tostring, xpcall
+      local coroutine, package, string = coroutine, package, string
+      local coroutine_resume = coroutine.resume
+      local coroutine_running = coroutine.running
+      local coroutine_status = coroutine.status
+      local coroutine_yield = coroutine.yield
+      local io_type = io.type
+
+
+      -- make package.searchers available as an alias for package.loaders
+      local p_index = { searchers = package.loaders }
+      setmetatable(package, {
+         __index = p_index,
+         __newindex = function(p, k, v)
+            if k == "searchers" then
+               rawset(p, "loaders", v)
+               p_index.searchers = v
+            else
+               rawset(p, k, v)
+            end
+         end
+      })
+
+
+      if type(file_meta) == "table" and type(file_meta.__index) == "table" then
+         if not is_luajit then
+            local function helper(_, var_1, ...)
+               if var_1 == nil then
+                  if (...) ~= nil then
+                     error((...), 2)
+                  end
+               end
+               return var_1, ...
+            end
+
+            local function lines_iterator(st)
+               return helper(st, st.f:read(unpack(st, 1, st.n)))
+            end
+
+            local file_write = file_meta.__index.write
+            file_meta.__index.write = function(self, ...)
+               local res, msg, errno = file_write(self, ...)
+               if res then
+                  return self
+               else
+                  return nil, msg, errno
+               end
+            end
+
+            file_meta.__index.lines = function(self, ...)
+               if io_type(self) == "closed file" then
+                  error("attempt to use a closed file", 2)
+               end
+               local st = { f=self, n=select('#', ...), ... }
+               for i = 1, st.n do
+                  local t = type(st[i])
+                  if t == "string" then
+                     local fmt = st[i]:match("^*?([aln])")
+                     if not fmt then
+                        error("bad argument #"..(i+1).." to 'for iterator' (invalid format)", 2)
+                     end
+                     st[i] = "*"..fmt
+                  elseif t ~= "number" then
+                     error("bad argument #"..(i+1).." to 'for iterator' (invalid format)", 2)
+                  end
+               end
+               return lines_iterator, st
+            end
+         end -- not luajit
+      end -- file_meta valid
+
+
+      -- the (x)pcall implementations start a new coroutine internally
+      -- to allow yielding even in Lua 5.1. to allow for accurate
+      -- stack traces we keep track of the nested coroutine activations
+      -- in the weak tables below:
+      local weak_meta = { __mode = "kv" }
+      -- maps the internal pcall coroutines to the user coroutine that
+      -- *should* be running if pcall didn't use coroutines internally
+      local pcall_mainOf = setmetatable({}, weak_meta)
+      -- table that maps each running coroutine started by pcall to
+      -- the coroutine that resumed it (user coroutine *or* pcall
+      -- coroutine!)
+      local pcall_previous = setmetatable({}, weak_meta)
+      -- reverse of `pcall_mainOf`. maps a user coroutine to the
+      -- currently active pcall coroutine started within it
+      local pcall_callOf = setmetatable({}, weak_meta)
+      -- similar to `pcall_mainOf` but is used only while executing
+      -- the error handler of xpcall (thus no nesting is necessary!)
+      local xpcall_running = setmetatable({}, weak_meta)
+
+      -- handle debug functions
+      if type(debug) == "table" then
+         local debug_getinfo = debug.getinfo
+         local debug_traceback = debug.traceback
+
+         if not is_luajit then
+            local function calculate_trace_level(co, level)
+               if level ~= nil then
+                  for out = 1, 1/0 do
+                     local info = (co==nil) and debug_getinfo(out, "") or debug_getinfo(co, out, "")
+                     if info == nil then
+                        local max = out-1
+                        if level <= max then
+                           return level
+                        end
+                        return nil, level-max
+                     end
+                  end
+               end
+               return 1
+            end
+
+            local stack_pattern = "\nstack traceback:"
+            local stack_replace = ""
+            function debug.traceback(co, msg, level)
+               local lvl
+               local nilmsg
+               if type(co) ~= "thread" then
+                  co, msg, level = coroutine_running(), co, msg
+               end
+               if msg == nil then
+                  msg = ""
+                  nilmsg = true
+               elseif type(msg) ~= "string" then
+                  return msg
+               end
+               if co == nil then
+                  msg = debug_traceback(msg, level or 1)
+               else
+                  local xpco = xpcall_running[co]
+                  if xpco ~= nil then
+                     lvl, level = calculate_trace_level(xpco, level)
+                     if lvl then
+                        msg = debug_traceback(xpco, msg, lvl)
+                     else
+                        msg = msg..stack_pattern
+                     end
+                     lvl, level = calculate_trace_level(co, level)
+                     if lvl then
+                        local trace = debug_traceback(co, "", lvl)
+                        msg = msg..trace:gsub(stack_pattern, stack_replace)
+                     end
+                  else
+                     co = pcall_callOf[co] or co
+                     lvl, level = calculate_trace_level(co, level)
+                     if lvl then
+                        msg = debug_traceback(co, msg, lvl)
+                     else
+                        msg = msg..stack_pattern
+                     end
+                  end
+                  co = pcall_previous[co]
+                  while co ~= nil do
+                     lvl, level = calculate_trace_level(co, level)
+                     if lvl then
+                        local trace = debug_traceback(co, "", lvl)
+                        msg = msg..trace:gsub(stack_pattern, stack_replace)
+                     end
+                     co = pcall_previous[co]
+                  end
+               end
+               if nilmsg then
+                  msg = msg:gsub("^\n", "")
+               end
+               msg = msg:gsub("\n\t%(tail call%): %?", "\000")
+               msg = msg:gsub("\n\t%.%.%.\n", "\001\n")
+               msg = msg:gsub("\n\t%.%.%.$", "\001")
+               msg = msg:gsub("(%z+)\001(%z+)", function(some, other)
+                  return "\n\t(..."..#some+#other.."+ tail call(s)...)"
+               end)
+               msg = msg:gsub("\001(%z+)", function(zeros)
+                  return "\n\t(..."..#zeros.."+ tail call(s)...)"
+               end)
+               msg = msg:gsub("(%z+)\001", function(zeros)
+                  return "\n\t(..."..#zeros.."+ tail call(s)...)"
+               end)
+               msg = msg:gsub("%z+", function(zeros)
+                  return "\n\t(..."..#zeros.." tail call(s)...)"
+               end)
+               msg = msg:gsub("\001", function()
+                  return "\n\t..."
+               end)
+               return msg
+            end
+         end -- is not luajit
+      end -- debug table available
+
+
+      if not is_luajit52 then
+         local coroutine_running52 = M.coroutine.running
+         function M.coroutine.running()
+            local co, ismain = coroutine_running52()
+            if ismain then
+               return co, true
+            else
+               return pcall_mainOf[co] or co, false
+            end
+         end
+      end
+
+      if not is_luajit then
+         local function pcall_results(current, call, success, ...)
+            if coroutine_status(call) == "suspended" then
+               return pcall_results(current, call, coroutine_resume(call, coroutine_yield(...)))
+            end
+            if pcall_previous then
+               pcall_previous[call] = nil
+               local main = pcall_mainOf[call]
+               if main == current then current = nil end
+               pcall_callOf[main] = current
+            end
+            pcall_mainOf[call] = nil
+            return success, ...
+         end
+
+         local function pcall_exec(current, call, ...)
+            local main = pcall_mainOf[current] or current
+            pcall_mainOf[call] = main
+            if pcall_previous then
+               pcall_previous[call] = current
+               pcall_callOf[main] = call
+            end
+            return pcall_results(current, call, coroutine_resume(call, ...))
+         end
+
+         local coroutine_create52 = M.coroutine.create
+
+         local function pcall_coroutine(func)
+            if type(func) ~= "function" then
+               local callable = func
+               func = function (...) return callable(...) end
+            end
+            return coroutine_create52(func)
+         end
+
+         function M.pcall(func, ...)
+            local current = coroutine_running()
+            if not current then return pcall(func, ...) end
+            return pcall_exec(current, pcall_coroutine(func), ...)
+         end
+
+         local function xpcall_catch(current, call, msgh, success, ...)
+            if not success then
+               xpcall_running[current] = call
+               local ok, result = pcall(msgh, ...)
+               xpcall_running[current] = nil
+               if not ok then
+                  return false, "error in error handling ("..tostring(result)..")"
+               end
+               return false, result
+            end
+            return true, ...
+         end
+
+         function M.xpcall(f, msgh, ...)
+            local current = coroutine_running()
+            if not current then
+               local args, n = { ... }, select('#', ...)
+               return xpcall(function() return f(unpack(args, 1, n)) end, msgh)
+            end
+            local call = pcall_coroutine(f)
+            return xpcall_catch(current, call, msgh, pcall_exec(current, call, ...))
+         end
+      end -- not luajit
+
+   end -- lua 5.1
+
+
+   -- handle exporting to global scope
+   local function extend_table(from, to)
+      if from ~= to then
+         for k,v in pairs(from) do
+            if type(v) == "table" and
+               type(to[k]) == "table" and
+               v ~= to[k] then
+               extend_table(v, to[k])
+            else
+               to[k] = v
+            end
+         end
+      end
+   end
+
+   extend_table(M, _G)
+
+end -- lua < 5.3
+
+-- vi: set expandtab softtabstop=3 shiftwidth=3 :