feat: Field and attribute parsing

src/Language/Java/Classfile/Fields.hs

@@ -0,0 +1,55 @@
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE DerivingVia #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE InstanceSigs #-}
+{-# LANGUAGE LambdaCase #-}
+module Language.Java.Classfile.Fields (Fields(..)) where
+import Data.Array.IArray (Array)
+import Data.Word (Word16)
+import Language.Java.Classfile.Extractable (Extractable)
+import GHC.Generics ( Generically, Generic, Generically(..) )
+import Language.Java.Classfile.Flags (Flags)
+import Language.Java.Classfile.Flag (FlagMask (..))
+import Language.Java.Classfile.ConstantPool.References (Utf8Reference)
+import Language.Java.Classfile.Attributes (Attributes)
+
+newtype Fields = Fields (Array Word16 Field)
+  deriving stock Show
+  deriving newtype Extractable
+
+data FieldFlag
+  = Public
+  | Private
+  | Protected
+  | Static
+  | Final
+  | Volatile
+  | Transient
+  | Synthetic
+  | Enumeration -- original "Enum"
+  deriving stock (Show, Eq, Ord, Enum, Bounded)
+
+instance FlagMask FieldFlag where
+  type FlagType FieldFlag = Word16
+  maskOf :: FieldFlag -> FlagType FieldFlag
+  maskOf = \case
+    Public      -> 0x0001
+    Private     -> 0x0002
+    Protected   -> 0x0004
+    Static      -> 0x0008
+    Final       -> 0x0010
+    Volatile    -> 0x0040
+    Transient   -> 0x0080
+    Synthetic   -> 0x1000
+    Enumeration -> 0x4000
+
+
+data Field = Field
+  { flags      :: Flags FieldFlag
+  , name       :: Utf8Reference
+  , descriptor :: Utf8Reference
+  , attribute  :: Attributes
+  }
+  deriving stock (Show, Generic)
+  deriving Extractable via Generically Field