JVM.ClassFile

This module declares (low-level) data types for Java .class files structures, and Binary instances to read/write them.

About

Java .class file uses constants pool, which stores almost all source-code-level constants (strings, integer literals etc), and also all identifiers (class, method, field names etc). All other structures contain indexes of constants in the pool instead of constants theirself.

It's not convient to use that indexes programmatically. So, .class file is represented at two stages: File and Direct. At File stage, all data structures contain only indexes, not constants theirself. When we read a class from a file, we get structure at File stage. We only can write File stage structure to file.

At Direct stage, structures conain constants, not indexes. Convertion functions (File - Direct) are located in the JVM.Converter module.

data Attribute

Any (class field method/ ...) attribute format. Some formats specify special formats for attributeValue.

Constructors

Attribute

Fields

attributeName :: Word16

attributeLength :: Word32

attributeValue :: ByteString

Instances

Eq Attribute

Show Attribute

Binary Attribute

BinaryState Integer Attribute

data FieldType

Field signature format

Constructors

SignedByte

B

CharByte

C

DoubleType

D

FloatType

F

IntType

I

LongInt

J

ShortInt

S

BoolType

Z

ObjectType String

L {class name}

Array (Maybe Int) FieldType

[{type}

Instances

Eq FieldType

Show FieldType

Binary FieldType

Signatures

type FieldSignature = FieldType

Class field signature

data MethodSignature

Class method argument signature

Constructors

MethodSignature [ArgumentSignature] ReturnSignature

Instances

Eq MethodSignature

Show MethodSignature

Binary MethodSignature

data ReturnSignature

Return value signature

Constructors

Returns FieldType

ReturnsVoid

Instances

Eq ReturnSignature

Show ReturnSignature

Binary ReturnSignature

type ArgumentSignature = FieldType

Method argument signature

Stage types

data File

File stage

Instances

Eq (Method File)

Eq (Field File)

Eq (Class File)

Eq (Constant File)

Eq (Attributes File)

Show (Method File)

Show (Field File)

Show (Class File)

Show (Constant File)

Show (Attributes File)

Binary (Method File)

Binary (Field File)

Binary (Class File)

Default (Attributes File)

data Direct

Direct representation stage

Instances

Eq (Method Direct)

Eq (Field Direct)

Eq (Class Direct)

Eq (Constant Direct)

Eq (Attributes Direct)

Show (Method Direct)

Show (Field Direct)

Show (Class Direct)

Show (Constant Direct)

Show (Attributes Direct)

Default (Attributes Direct)

HasSignature (Method Direct)

HasSignature (Field Direct)

Staged structures

type Pool stage = Map Word16 (Constant stage)

Constant pool

type family Link stage a

Link to some object

data Method stage

Class method format

Constructors

Method

Fields

methodAccessFlags :: AccessFlags stage

methodName :: Link stage ByteString

methodSignature :: Link stage MethodSignature

methodAttributesCount :: Word16

methodAttributes :: Attributes stage

Instances

HasAttributes Method

Eq (Method Direct)

Eq (Method File)

Show (Method Direct)

Show (Method File)

Binary (Method File)

HasSignature (Method Direct)

data Field stage

Class field format

Constructors

Field

Fields

fieldAccessFlags :: AccessFlags stage

fieldName :: Link stage ByteString

fieldSignature :: Link stage FieldSignature

fieldAttributesCount :: Word16

fieldAttributes :: Attributes stage

Instances

HasAttributes Field

Eq (Field Direct)

Eq (Field File)

Show (Field Direct)

Show (Field File)

Binary (Field File)

HasSignature (Field Direct)

data Class stage

Generic .class file format

Constructors

Class

Fields

magic :: Word32

Magic value: 0xCAFEBABE

minorVersion :: Word16

majorVersion :: Word16

constsPoolSize :: Word16

Number of items in constants pool

constsPool :: Pool stage

Constants pool itself

accessFlags :: AccessFlags stage

See JVM.Types.AccessFlag

thisClass :: Link stage ByteString

Constants pool item index for this class

superClass :: Link stage ByteString

• -/-- for super class, zero for java.lang.Object

interfacesCount :: Word16

Number of implemented interfaces

interfaces :: [Link stage ByteString]

Constants pool item indexes for implemented interfaces

classFieldsCount :: Word16

Number of class fileds

classFields :: [Field stage]

Class fields

classMethodsCount :: Word16

Number of class methods

classMethods :: [Method stage]

Class methods

classAttributesCount :: Word16

Number of class attributes

classAttributes :: Attributes stage

Class attributes

Instances

HasAttributes Class

Eq (Class Direct)

Eq (Class File)

Show (Class Direct)

Show (Class File)

Binary (Class File)

data Constant stage

Constant pool item

Constructors

CClass (Link stage ByteString)

CField (Link stage ByteString) (Link stage (NameType (Field stage)))

CMethod (Link stage ByteString) (Link stage (NameType (Method stage)))

CIfaceMethod (Link stage ByteString) (Link stage (NameType (Method stage)))

CString (Link stage ByteString)

CInteger Word32

CFloat Float

CLong Word64

CDouble Double

CNameType (Link stage ByteString) (Link stage ByteString)

CUTF8

Fields

getString :: ByteString

CUnicode

Fields

getString :: ByteString

Instances

Eq (Constant Direct)

Eq (Constant File)

Show (Constant Direct)

Show (Constant File)

data AccessFlag

Access flags. Used for classess, methods, variables.

Constructors

ACC_PUBLIC

0x0001 Visible for all

ACC_PRIVATE

0x0002 Visible only for defined class

ACC_PROTECTED

0x0004 Visible only for subclasses

ACC_STATIC

0x0008 Static method or variable

ACC_FINAL

0x0010 No further subclassing or assignments

ACC_SYNCHRONIZED

0x0020 Uses monitors

ACC_VOLATILE

0x0040 Could not be cached

ACC_TRANSIENT

0x0080

ACC_NATIVE

0x0100 Implemented in other language

ACC_INTERFACE

0x0200 Class is interface

ACC_ABSTRACT

0x0400

Instances

Enum AccessFlag

Eq AccessFlag

Ord AccessFlag

Show AccessFlag

type family AccessFlags stage

Object (class, method, field …) access flags

data family Attributes stage

Object (class, method, field) attributes

defaultClass :: (Default (AccessFlags stage), Default (Link stage ByteString), Default (Attributes stage)) => Class stage

Default (empty) class file definition.

Misc

class (Binary (Signature a), Show (Signature a), Eq (Signature a)) => HasSignature a

Fields and methods have signatures.

Associated Types

type Signature a

Instances

HasSignature (Method Direct)

HasSignature (Field Direct)

class HasAttributes a where

Methods

attributes :: a stage -> Attributes stage

Instances

HasAttributes Method

HasAttributes Field

HasAttributes Class

data NameType a

Name and signature pair. Used for methods and fields.

Constructors

NameType

Fields

ntName :: ByteString

ntSignature :: Signature a

Instances

HasSignature a => Eq (NameType a)

HasSignature a => Show (NameType a)

HasSignature a => Binary (NameType a)

fieldNameType :: Field Direct -> NameType (Field Direct)

methodNameType :: Method Direct -> NameType (Method Direct)

lookupField :: ByteString -> Class Direct -> Maybe (Field Direct)

lookupMethod :: ByteString -> Class Direct -> Maybe (Method Direct)

long :: Constant stage -> Bool

toString :: ByteString -> String

className :: Constant Direct -> ByteString

Name of the CClass. Error on any other constant.

apsize :: Attributes File -> Int

Size of attributes set at File stage

arsize :: Attributes Direct -> Int

Size of attributes set at Direct stage

arlist :: Attributes Direct -> [(ByteString, ByteString)]

Associative list of attributes at Direct stage