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module Main where
import Char
import System
--- translation from Symbolic JVM to real Jasmin code
main :: IO ()
main = do
jvm:src:_ <- getArgs
s <- readFile jvm
let cls = takeWhile (/='.') src
let obj = cls ++ ".j"
writeFile obj $ boilerplate cls
appendFile obj $ mkJVM cls s
putStrLn $ "wrote file " ++ obj
system $ "jasmin " ++ obj
return ()
mkJVM :: String -> String -> String
mkJVM cls = unlines . reverse . fst . foldl trans ([],([],0)) . lines where
trans (code,(env,v)) s = case words s of
".method":p:s:f:ns
| f == "main" ->
(".method public static main([Ljava/lang/String;)V":code,([],1))
| otherwise ->
(unwords [".method",p,s, f ++ typesig ns] : code,([],0))
"alloc":t:x:_ -> (("; " ++ s):code, ((x,v):env, v + size t))
".limit":"locals":ns -> chCode (".limit locals " ++ show (length ns))
"invokestatic":t:f:ns
| take 8 f == "runtime/" ->
chCode $ "invokestatic " ++ "runtime/" ++ t ++ drop 8 f ++ typesig ns
"invokestatic":f:ns ->
chCode $ "invokestatic " ++ cls ++ "/" ++ f ++ typesig ns
"alloc":ns -> chCode $ "; " ++ s
t:('_':instr):[";"] -> chCode $ t ++ instr
t:('_':instr):x:_ -> chCode $ t ++ instr ++ " " ++ look x
"goto":ns -> chCode $ "goto " ++ label ns
"ifeq":ns -> chCode $ "ifeq " ++ label ns
"label":ns -> chCode $ label ns ++ ":"
";":[] -> chCode ""
_ -> chCode s
where
chCode c = (c:code,(env,v))
look x = maybe (error $ x ++ show env) show $ lookup x env
typesig = init . map toUpper . concat
label = init . concat
size t = case t of
"d" -> 2
_ -> 1
boilerplate :: String -> String
boilerplate cls = unlines [
".class public " ++ cls,
".super java/lang/Object",
".method public <init>()V",
"aload_0",
"invokenonvirtual java/lang/Object/<init>()V",
"return",
".end method"
]
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