build(lua): vendor coxpcall

Do not require luarocks on PUC lua CI just because of this single lua file

runtime/lua/coxpcall.lua

@@ -0,0 +1,108 @@
+-------------------------------------------------------------------------------
+-- Coroutine safe xpcall and pcall versions
+--
+-- Encapsulates the protected calls with a coroutine based loop, so errors can
+-- be dealed without the usual Lua 5.x pcall/xpcall issues with coroutines
+-- yielding inside the call to pcall or xpcall.
+--
+-- Authors: Roberto Ierusalimschy and Andre Carregal
+-- Contributors: Thomas Harning Jr., Ignacio Burgueño, Fabio Mascarenhas
+--
+-- Copyright 2005 - Kepler Project
+--
+-- $Id: coxpcall.lua,v 1.13 2008/05/19 19:20:02 mascarenhas Exp $
+-------------------------------------------------------------------------------
+
+-------------------------------------------------------------------------------
+-- Checks if (x)pcall function is coroutine safe
+-------------------------------------------------------------------------------
+local function isCoroutineSafe(func)
+    local co = coroutine.create(function()
+        return func(coroutine.yield, function() end)
+    end)
+
+    coroutine.resume(co)
+    return coroutine.resume(co)
+end
+
+-- No need to do anything if pcall and xpcall are already safe.
+if isCoroutineSafe(pcall) and isCoroutineSafe(xpcall) then
+    copcall = pcall
+    coxpcall = xpcall
+    return { pcall = pcall, xpcall = xpcall, running = coroutine.running }
+end
+
+-------------------------------------------------------------------------------
+-- Implements xpcall with coroutines
+-------------------------------------------------------------------------------
+local performResume, handleReturnValue
+local oldpcall, oldxpcall = pcall, xpcall
+local pack = table.pack or function(...) return {n = select("#", ...), ...} end
+local unpack = table.unpack or unpack
+local running = coroutine.running
+local coromap = setmetatable({}, { __mode = "k" })
+
+function handleReturnValue(err, co, status, ...)
+    if not status then
+        return false, err(debug.traceback(co, (...)), ...)
+    end
+    if coroutine.status(co) == 'suspended' then
+        return performResume(err, co, coroutine.yield(...))
+    else
+        return true, ...
+    end
+end
+
+function performResume(err, co, ...)
+    return handleReturnValue(err, co, coroutine.resume(co, ...))
+end
+
+local function id(trace, ...)
+    return trace
+end
+
+function coxpcall(f, err, ...)
+    local current = running()
+    if not current then
+        if err == id then
+            return oldpcall(f, ...)
+        else
+            if select("#", ...) > 0 then
+                local oldf, params = f, pack(...)
+                f = function() return oldf(unpack(params, 1, params.n)) end
+            end
+            return oldxpcall(f, err)
+        end
+    else
+        local res, co = oldpcall(coroutine.create, f)
+        if not res then
+            local newf = function(...) return f(...) end
+            co = coroutine.create(newf)
+        end
+        coromap[co] = current
+        return performResume(err, co, ...)
+    end
+end
+
+local function corunning(coro)
+  if coro ~= nil then
+    assert(type(coro)=="thread", "Bad argument; expected thread, got: "..type(coro))
+  else
+    coro = running()
+  end
+  while coromap[coro] do
+    coro = coromap[coro]
+  end
+  if coro == "mainthread" then return nil end
+  return coro
+end
+
+-------------------------------------------------------------------------------
+-- Implements pcall with coroutines
+-------------------------------------------------------------------------------
+
+function copcall(f, ...)
+    return coxpcall(f, id, ...)
+end
+
+return { pcall = copcall, xpcall = coxpcall, running = corunning }