Add graph coloring register allocator.

[ghc-hetmet.git] / compiler / utils / State.hs

diff --git a/compiler/utils/State.hs b/compiler/utils/State.hs
new file mode 100644 (file)
index 0000000..faed566
--- /dev/null
+++ b/compiler/utils/State.hs
@@ -0,0 +1,31 @@
+
+module State where
+
+newtype State s a
+       = State
+       { runState :: s -> (# a, s #) }
+
+instance Monad (State s) where
+    return x   = State $ \s -> (# x, s #)
+    m >>= n    = State $ \s ->
+                       case runState m s of
+                         (# r, s' #)   -> runState (n r) s'
+
+get :: State s s
+get    = State $ \s -> (# s, s #)
+
+put ::         s -> State s ()
+put s' = State $ \s -> (# (), s' #)
+
+modify :: (s -> s) -> State s ()
+modify f = State $ \s -> (# (), f s #)
+
+evalState :: State s a -> s -> a
+evalState s i
+       = case runState s i of
+               (# a, s' #)     -> a
+
+execState :: State s a -> s -> s
+execState s i
+       = case runState s i of
+               (# a, s' #)     -> s'