ConstantValue.hs

{-# LANGUAGE DeriveAnyClass     #-}
{-# LANGUAGE DeriveGeneric      #-}
{-# LANGUAGE FlexibleInstances  #-}
{-# LANGUAGE OverloadedStrings  #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE TemplateHaskell    #-}
{-|
Module      : Language.JVM.Attribute.ConstantValue
Copyright   : (c) Christian Gram Kalhauge, 2017
License     : MIT
Maintainer  : kalhuage@cs.ucla.edu

Based on the ConstantValue, as documented [here](http://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.5).
-}

module Language.JVM.Attribute.ConstantValue
  ( ConstantValue (..)
  ) where

import           Language.JVM.Attribute.Base
import           Language.JVM.Constant
import           Language.JVM.Staged

-- | 'ConstantValue' is an Attribute.
instance IsAttribute (ConstantValue Low) where
  attrName = Const "ConstantValue"


-- | A constant value is just a index into the constant pool.
data ConstantValue r = ConstantValue
  { constantValue :: !(Ref JValue r)
  }

instance Staged ConstantValue where
  evolve (ConstantValue r) =
    ConstantValue <$> link r
  devolve (ConstantValue r) =
    ConstantValue <$> unlink r

$(deriveBaseWithBinary ''ConstantValue)