README.md

RJVM

This project is an attempt to write a minimal JVM using Rust.

It is a hobby project, built for fun and for learning purposes. The code quality is definitely not production ready - there are not enough tests, there isn't enough documentation, and some parts might not be idiomatic Rust since I'm just learning it. 😊

The code is licensed under the Apache v2 license.

Status

The current code can execute a very simple program.

• reading class files
  • class attributes
    • InnerClasses
    • EnclosingMethod
    • synthetic
    • signature
    • SourceFile
    • SourceDebugExtension
    • deprecated
    • runtime visible annotations
    • runtime invisible annotations
    • BootstrapMethods
  • methods
    • code
      • exception tables
      • attributes
        • LineNumberTable
        • LocalVariableTable
        • LocalVariableTypeTable
        • StackMapTable
    • source code mappings
    • attributes
      • synthetic
      • signature
      • deprecated
      • exceptions
      • runtime visible annotations
      • runtime invisible annotations
      • runtime visible parameter annotations
      • runtime invisible parameter annotations
      • annotation default
  • field
    • attributes
      • constant value
      • synthetic
      • signature
      • deprecated
      • runtime visible annotations
      • runtime invisible annotations
• execution
  • data types
    • primitives
      • int
      • short
      • char
      • byte
      • long
      • float
      • double
      • boolean
      • object
      • primitive arrays
      • object arrays
      • multidimensional arrays
  • new object instances creation
  • static methods invocation
  • virtual methods invocation
  • modelling of super classes
  • abstract methods
  • control flow
  • exceptions
  • object allocations and garbage collection
  • threading
  • tons of other features :-)

Structure

The code is currently structured in three crates:

• utils, which contains some common code, unrelated to the JVM;
• reader, with the .class file reader and the data structure for modelling them;
• vm, which contains the virtual machine that can execute the code.

There are some unit test and some integration tests - probably not enough, but since this is not production code but just a learning exercise, I'm not that worried about it.