Improve inline function for huge performance increases. New tests.

spec/dummy/inlineFunction.lua

@@ -0,0 +1,2 @@
+
+return foo, bat

spec/inline_spec.lua

@@ -0,0 +1,24 @@
+package.path = 'src/?.lua;'..package.path
+
+describe('verify that inline handles environments properly', function()
+  local util = require 'util'
+
+  after_each(function()
+    util.clearCache()
+  end)
+
+  it('can set an environment', function()
+    local env = {foo='bar'}
+    assert('bar' == util.inline('spec.dummy.inlineFunction', env))
+  end)
+
+  it('can set an environment with multiple variables', function()
+    local env = {foo='bar', bat='baz'}
+    assert.same({'bar','baz'}, {util.inline('spec.dummy.inlineFunction', env)})
+  end)
+
+  it('can set an environment with no variables', function()
+    local env = {}
+    assert.equal(nil, util.inline('spec.dummy.inlineFunction', env))
+  end)
+end)

src/util.lua

@@ -1,25 +1,53 @@
-local loader, loaded = package.loaders[2], package.loaded
+local loaded = {}
 
-local inlineMeta = {
-  __index = function(self, key)
-    return rawget(self, key) or _G[key]
+local function loadModule(name)
+  local errors = {}
+  -- Find source
+  local modulePath = string.gsub(name, "%.", "/")
+  for path in string.gmatch(package.path, "([^;]+)") do
+    local fileName = string.gsub(path, "%?", modulePath)
+    local file = io.open(fileName, "rb")
+    if file then
+      return file:read("*a")
+    end
+    errors[#errors+1] = "\n\tno file '"..fileName.."' (attempted with lusty inline)"
   end
-}
+  return nil, table.concat(errors)
+end
 
 --load file, memoize, execute loaded function inside environment
 local function inline(name, env)
   local file = loaded[name]
   if not file then
-    file = string.dump(loader(name))
+    local code, err = loadModule(name)
+    if not code then
+      error(err)
+    end
+    local keys ={}
+    for k in pairs(env) do
+      keys[#keys+1] = k
+    end
+
+    if #keys > 0 then
+      file, err = loadstring(
+        'local _env=select(1, ...)\nlocal '..table.concat(keys, ',')..
+        "=_env."..table.concat(keys, ",_env.")..
+        '\n'..code
+      )
+    else
+      file, err = loadstring(code)
+    end
+    if not file then error(err) end
     loaded[name] = file
   end
-  file = loadstring(file)
-  if type(file) == 'string' then
-    error(file)
-  end
-  return setfenv(file, setmetatable(env, inlineMeta))(name)
+  return file(env)
+end
+
+local function clearCache()
+  loaded = {}
 end
 
 return {
-  inline = inline
+  inline = inline,
+  clearCache = clearCache,
 }