Allow transpile.lua to be run directly.

• Fix `async for` loops inside asynchronous functions.
 • Allow transpile.lua to be called directly.

README.md

@@ -173,6 +173,21 @@ The following functions only work inside coroutines:
 The custom lua syntax introduced by this mod is "transpiled" back into regular
 lua, and can only be used with `asyncio.dofile` etc.
 
+### Pre-runtime transpiling
+
+**If you are going to be using Minetest's insecure environment from a file
+using this custom syntax, I strongly recommend avoiding `asyncio.loadfile`
+etc.**
+
+To invoke the transpiler outside of Minetest, you can simply run
+`lua transpile.lua /path/to/file.async.lua`. This should print the transpiled
+code. If you want it to write the transpiled code to a different file, provided
+you are on a UNIX-like OS, you can run
+`lua transpile.lua file.async.lua > file.lua`.
+
+*Note that `async for` loops will always be mangled ensure compatibility with
+Lua 5.1.*
+
 ## Coroutines
 
 asyncio coroutines can be created in one of two ways:

core.lua

@@ -200,6 +200,7 @@ local function iter(func, ...)
     end
 end
 asyncio.iter = iter
+asyncio._iter_start = iter
 
 -- Lua 5.1 (excluding LuaJIT) compatibility
 asyncio.lua51 = _VERSION < 'Lua 5.2'

locks.lua

@@ -10,8 +10,8 @@
 local lock_states = {}
 local lock_callbacks = {}
 
-setmetatable(lock_states,  {__mode = 'kv'})
-setmetatable(lock_callbacks,  {__mode = 'k'})
+setmetatable(lock_states, {__mode = 'kv'})
+setmetatable(lock_callbacks, {__mode = 'k'})
 
 -- Create the functions
 -- https://docs.python.org/3/library/asyncio-sync.html#lock

lua51.lua

@@ -7,10 +7,6 @@ local rawequal = rawequal
 minetest.log('warning', '[asyncio] LuaJIT not installed, asyncio.iter() ' ..
     'will be less efficient.')
 
--- Keep the original asyncio.iter accessible, this is used in the workaround
--- iter function and in the transpiler.
-asyncio._iter_start = asyncio.iter
-
 -- Helper functions
 local function pack_len(...)
     local res = {...}

transpile.lua

@@ -18,6 +18,7 @@ end
 
 -- Matches
 -- These take 2-3 arguments (code, res, char) and should return code and res.
+local lua51 = not asyncio or asyncio.lua51
 local matches
 matches = {
     -- Handle multi-line strings and comments
@@ -121,6 +122,12 @@ matches = {
                 local func = matches[char] or matches[pattern]
                 assert(func, 'No function found for pattern!')
                 code, res = func(code:sub(e + 1), res, char)
+
+                -- Increase the level for async for loops
+                if lua51 and (pattern == '^async for ' or
+                        pattern == '[%s;%[]async for ') then
+                    lvl = lvl + 1
+                end
             end
         end
 
@@ -147,7 +154,7 @@ matches = {
 }
 
 -- A workaround for Lua 5.1's iterator limitations.
-if not asyncio or asyncio.lua51 then
+if lua51 then
     local orig = matches['async for ']
     matches['async for '] = function(code, res, char)
         if char:sub(1, 1) ~= 'a' then res = res .. char:sub(1, 1) end
@@ -209,12 +216,36 @@ local function transpile(code)
     return res .. code
 end
 
--- Testing
-if not asyncio then
-    local f = io.open('test.lua')
-    print(transpile(f:read '*a'))
+-- Handle being called outside of Minetest.
+if not asyncio or not minetest then
+    -- If this is called via dofile(), just return the function.
+    if not arg or debug.getinfo(3) then
+        return transpile
+    end
 
-    return transpile
+    if not arg[1] or arg[1] == '' then
+        print('Invalid usage.')
+        print('Usage: transpile.lua <file>')
+        os.exit(1)
+    end
+
+    -- Read the file
+    local f, err, errcode = io.open(arg[1], 'r')
+    if not f then
+        print(err)
+        os.exit(errcode)
+    end
+
+    local code, err, errcode = f:read('*a')
+    f:close()
+    if not code then
+        print(err)
+        os.exit(errcode)
+    end
+
+    -- Print the output
+    print(transpile(code))
+    os.exit(0)
 end
 
 -- Lua 5.2+ compatibility