mzarnowski / jspawn Goto Github PK

Goals:
Spawned class can be instantiated using default constructor:

Class<?> spawned = ???;
Object instance = spawned.getDeclaredConstructor().newInstance();

Finished when:

1. One can access a field of spawned class using reflection, e.g. spawnedClass.getDeclaredField("field").
2. This field's getType method returns 'correct' type

Goal:

1. support for returning following primitives:
   byte, short, long, float, double, char, boolean

Non-Goal:

1. support for array/object to be returned

Currently, class file is build in abstract steps defined in so called "compiler" package. But, since the process is very straightforward, we can simplify it a lot by introducing separate factories for many of these steps.

Gain:

1. create class file explicitly and in a simpler manner
2. define logic of creating objects (ClassFile, its pools) more closely to the actual object definitions

Goals:

1. A method returning an int can be obtained from a spawned class using reflection:

Class<?> spawned = ???
Method method = spawned.getDeclaredMethod("foo", int.class);

2. This method, when invoked, will return - no surprises - an int value

Non-Goals:

1. Allowing any other than int return type
2. Introducing any non-push and non-return stack-instruction

Goals:

1. Define instructions for conversion between primitives

When:

1. request was made to spawn a class of name pkg.Bar, extending Foo and implementing IFace.

Then

1. We obtain an instance of Class named 'Bar' within package 'pkg'. It is assignable to both Foo and IFace

Goals:
A method can be obtained from a spawned class using reflection

Class<?> spawned = ???
spawned.getDeclaredMethod("foo");

Non-Goals:

1. Having a method return anything
2. Supporting methods with non-empty body

Goals:
Branching instruction consist of:
a) condition
b) target

supported conditions are:

ALWAYS, 
IF_EQUAL, IF_NOT_EQUAL, 
IF_SMALLER, IF_NOT_SMALLER,
IF_GREATER, IF_NOT_GREATER, 

IF_ZERO, IF_NOT_ZERO, 
IF_SMALLER_THAN_ZERO, IF_NOT_SMALLER_THAN_ZERO,
IF_GREATER_THAN_ZERO, IF_NOT_GREATER_THAN_ZERO, 

target should be represented by a new Label type. Alongside Label, a meta-instruction DefineLabel should be introduced. It would be interpreted during JVM instruction generation as 'assign current byte offset with given label'

Goal:

1. Rebuild class file (as far as it is currently supported) from an input stream.

Goals:
Reduction operations are ones, which take at least one operand from a stack and transform it in some predefined manner. A bit like a built in functions

Goals:

1. Define project formatting for IntelliJ

There is no gain in using shorts instead of integers. It only results in unnecessary conversions.