Language.JVM.Constant

This module contains the Constant type and the ConstantPool. These are essential for accessing data in the class-file.

Constant

data Constant

A constant is a multi word item in the ConstantPool. Each of the constructors are pretty much self expiatory from the types.

Constructors

String !SizedByteString16

Integer !Word32

Float !Word32

Long !Word64

Double !Word64

ClassRef !ConstantRef

StringRef !ConstantRef

FieldRef !ConstantRef !ConstantRef

MethodRef !ConstantRef !ConstantRef

InterfaceMethodRef !ConstantRef !ConstantRef

NameAndType !ConstantRef !ConstantRef

MethodHandle !Word8 !ConstantRef

MethodType !ConstantRef

InvokeDynamic !ConstantRef !ConstantRef

Instances

Eq Constant

Methods

(==) :: Constant -> Constant -> Bool

(/=) :: Constant -> Constant -> Bool

Show Constant

Methods

showsPrec :: Int -> Constant -> ShowS

show :: Constant -> String

showList :: [Constant] -> ShowS

Binary Constant

Methods

put :: Constant -> Put

get :: Get Constant

putList :: [Constant] -> Put

constantSize :: Constant -> Int

Some of the Constants take up more space in the constant pool than other. Notice that String and MethodType is not of size 32, but is still awarded value 1. This is due to an inconsistency in JVM.

newtype ConstantRef

A constant is referenced by the ConstantRef data type. It is just a 16 bit word, but wrapped for type safety.

Constructors

ConstantRef Word16

Instances

Eq ConstantRef

Methods

(==) :: ConstantRef -> ConstantRef -> Bool

(/=) :: ConstantRef -> ConstantRef -> Bool

Show ConstantRef

Methods

showsPrec :: Int -> ConstantRef -> ShowS

show :: ConstantRef -> String

showList :: [ConstantRef] -> ShowS

Generic ConstantRef

Associated Types

type Rep ConstantRef :: * -> *

Methods

from :: ConstantRef -> Rep ConstantRef x

to :: Rep ConstantRef x -> ConstantRef

Binary ConstantRef

Methods

put :: ConstantRef -> Put

get :: Get ConstantRef

putList :: [ConstantRef] -> Put

type Rep ConstantRef

type Rep ConstantRef = D1 (MetaData "ConstantRef" "Language.JVM.Constant" "jvm-binary-0.0.2-GeL1rLcsq7015yP1ec12qb" True) (C1 (MetaCons "ConstantRef" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Word16)))

Constant Pool

The ConstantPool contains all the constants, and is accessible using the Lookup methods.

newtype ConstantPool

A ConstantPool is just an IntMap. A IntMap is used, because constants are accessed after their byte-offset. constantSize

Constructors

ConstantPool

Fields

• unConstantPool :: IntMap Constant

Instances

Eq ConstantPool

Methods

(==) :: ConstantPool -> ConstantPool -> Bool

(/=) :: ConstantPool -> ConstantPool -> Bool

Show ConstantPool

Methods

showsPrec :: Int -> ConstantPool -> ShowS

show :: ConstantPool -> String

showList :: [ConstantPool] -> ShowS

Binary ConstantPool

Methods

put :: ConstantPool -> Put

get :: Get ConstantPool

putList :: [ConstantPool] -> Put

lookupConstant :: ConstantRef -> ConstantPool -> Maybe Constant

Lookup a Constant in the ConstantPool.

lookupText :: ConstantRef -> ConstantPool -> Maybe Text

Lookup a Text in the ConstantPool, returns Nothing if the reference does not point to something in the ConstantPool, if it points to something not a String Constant, or if it is impossible to decode the ByteString as Utf8.

lookupClassName :: ConstantRef -> ConstantPool -> Maybe Text

Lookup a class name in the ConstantPool, returns Nothing otherwise.

toListOfConstants :: ConstantPool -> [(ConstantRef, Constant)]

Return a list of reference-constant pairs.