Weed assembly statements

There's still an undefined in Assembly.hs. To get rid of it, I'll need to adjust
how I weed labels. Once that's finished, the rest should be fairly straightforward.

src/Mima/Parse/Assembly/Weed/Common.hs

@@ -0,0 +1,51 @@
+module Mima.Parse.Assembly.Weed.Common
+  ( Registers(..)
+  , emptyRegisters
+  , AlmostWord(..)
+  , WeedResult(..)
+  , emptyResult
+  ) where
+
+import qualified Data.Map as Map
+
+import           Mima.Flag
+import           Mima.Label
+import           Mima.Parse.Assembly.RawInstruction
+import           Mima.Word
+
+data Registers a = Registers
+  { rIAR :: Maybe a
+  , rACC :: Maybe MimaWord
+  , rRA  :: Maybe a
+  , rSP  :: Maybe a
+  , rFP  :: Maybe a
+  } deriving (Show)
+
+emptyRegisters :: Registers a
+emptyRegisters = Registers
+  { rIAR = Nothing
+  , rACC = Nothing
+  , rRA  = Nothing
+  , rSP  = Nothing
+  , rFP  = Nothing
+  }
+
+data AlmostWord a
+  = AInstruction (RawInstruction a)
+  | ALiteral MimaWord
+  deriving (Show)
+
+data WeedResult a = WeedResult
+  { wrRegisters :: Registers a
+  , wrMemory    :: Map.Map MimaAddress (AlmostWord a)
+  , wrLabels    :: Map.Map LabelName MimaAddress
+  , wrFlags     :: Map.Map Char [AddressRange]
+  } deriving (Show)
+
+emptyResult :: WeedResult a
+emptyResult = WeedResult
+  { wrRegisters = emptyRegisters
+  , wrMemory    = Map.empty
+  , wrLabels    = Map.empty
+  , wrFlags     = Map.empty
+  }