mbt-classfile

ClassFile parsing/writing support in Moonbit.
This library is not stable yet and subject to refactor. APIs may change frequently and bugs are likely to appear.

Based on JVMS Ch.4, version Java SE 24.

Goals

• Parse ClassFile
• Descriptor parser
• Signature parser
• Write ClassFile
• Bytecode [Dis]Assembler
  • Assembler not done yet!

javap

A simple tool that utilizes this library as its class file parser.

Sample output:

Compiled from Some(SourceFile({sourceFile: "Simple.java"}))
public super Simple
  minor version: 0
  major version: 65
  flags: [Public, Super]
  this_class: Simple
  super_class: Some(java/lang/Object)
  interfaces: 0, fields: 14, methods: 5, attributes: 2

Constant pool:
  #0 = MethodRef(class=java/lang/Object, name=<init>, type=()V)
  #1 = Class java/lang/Object
  #2 = NameAndType(name=<init>, type=()V)
  #3 = Utf8(java/lang/Object)
  #4 = Utf8(<init>)
  #5 = Utf8(()V)
  #6 = String()
  #7 = Utf8()
  #8 = FieldRef(class=Simple, name=finalStr, type=Ljava/lang/String;)
  #9 = Class Simple
  #10 = NameAndType(name=finalStr, type=Ljava/lang/String;)
  #11 = Utf8(Simple)
  #12 = Utf8(finalStr)
  #13 = Utf8(Ljava/lang/String;)
  #14 = Utf8(_pri)
  #15 = Utf8(_pub)
  #16 = Utf8(_prot)
  #17 = Utf8(_def)
  #18 = Utf8(i)
  #19 = Utf8(I)
  #20 = Utf8(d)
  #21 = Utf8(D)
  #22 = Utf8(f)
  #23 = Utf8(F)
  #24 = Utf8(l)
  #25 = Utf8(J)
  #26 = Utf8(ch)
  #27 = Utf8(C)
  #28 = Utf8(bl)
  #29 = Utf8(Z)
  #30 = Utf8(s)
  #31 = Utf8(S)
  #32 = Utf8(b)
  #33 = Utf8(B)
  #34 = Utf8(g)
  #35 = Utf8(Ljava/lang/Object;)
  #36 = Utf8(Signature)
  #37 = Utf8(TG;)
  #38 = Utf8(ConstantValue)
  #39 = Utf8(methodPublicVoid)
  #40 = Utf8((Ljava/lang/CharSequence;)V)
  #41 = Utf8(Code)
  #42 = Utf8(LineNumberTable)
  #43 = Utf8(<T::Ljava/lang/CharSequence;>(TT;)V)
  #44 = Utf8(methodPrivateString)
  #45 = Utf8(()Ljava/lang/Object;)
  #46 = Utf8(()TG;)
  #47 = Utf8(justGeneric)
  #48 = Utf8((Ljava/lang/Object;)V)
  #49 = Utf8(<T:Ljava/lang/Object;OtherParam:Ljava/lang/Object;>(TT;)V)
  #50 = Utf8(wildcard)
  #51 = Utf8((Ljava/lang/Class;)V)
  #52 = Utf8((Ljava/lang/Class<+Ljava/lang/CharSequence;>;)V)
  #53 = Utf8(<G:Ljava/lang/Object;>Ljava/lang/Object;)
  #54 = Utf8(SourceFile)
  #55 = Utf8(Simple.java)
Fields:
  private Ljava/lang/String; _pri;
  public Ljava/lang/String; _pub;
  protected Ljava/lang/String; _prot;
   Ljava/lang/String; _def;
   I i;
   D d;
   F f;
   J l;
   C ch;
   Z bl;
   S s;
   B b;
   Ljava/lang/Object; g;
  final Ljava/lang/String; finalStr;
Methods:
  public void methodPublicVoid(CharSequence)
    descriptor: (Ljava/lang/CharSequence;)V

    attributes:
      Code: max_stack=0, max_locals=2, code_length=1
        RETURN #None
      Signature({signature: "<T::Ljava/lang/CharSequence;>(TT;)V"})
  private Object methodPrivateString()
    descriptor: ()Ljava/lang/Object;

    attributes:
      Code: max_stack=1, max_locals=1, code_length=2
        ACONST_NULL None
        ARETURN #None
      Signature({signature: "()TG;"})
  public void justGeneric(Object)
    descriptor: (Ljava/lang/Object;)V

    attributes:
      Code: max_stack=0, max_locals=2, code_length=1
        RETURN #None
      Signature({signature: "<T:Ljava/lang/Object;OtherParam:Ljava/lang/Object;>(TT;)V"})
  public void wildcard(Class)
    descriptor: (Ljava/lang/Class;)V

    attributes:
      Code: max_stack=0, max_locals=2, code_length=1
        RETURN #None
      Signature({signature: "(Ljava/lang/Class<+Ljava/lang/CharSequence;>;)V"})
  public void <init>()
    descriptor: ()V

    attributes:
      Code: max_stack=2, max_locals=1, code_length=11
        ALOAD index:Some("0")
        INVOKESPECIAL target:java/lang/Object ()V
        ALOAD index:Some("0")
        LDC String()
        PUTFIELD Some("finalStr") type: Some("Ljava/lang/String;")
        RETURN #None
Total tests: 8, passed: 8, failed: 0.