jstubgen: A Python repository from jimbaker

Currently a POC to demonstrate the feasibility of generating type hints from Java classes to be used by MyPy and other Python type checkers.

Next steps:

Add support for generics from the full type signature of the method, instead of using Any (especially noticeable for container types like HashMap below).
Callable, etc, take parameters. Get these out of Java.
Union constructor/method overloading as used by Java so that only one __init__ method, etc is generated
Test against MyPy 2.7 support
Test against Jython 3.x code (necessary for full support of Python type functionality). Obviously this would be be best with a working Jython 3.x implemengtation, however since such code is, with a couple of exceptions, always legal Python 3.x code, this can be done using MyPy's existing static analysis support.
Obvious engineering improvements, again this is currently just a quick POC to show feasibility!

To run, you need to ensure the ASM 7.2 library jar is on your CLASSPATH; this can also be readily done if you are using a dev build of Jython, which doesn't move the org.objectweb.asm namespace into org.python.

Example:

$ jython jstubgen-poc.py java.util.HashMap
class HashMap(java.util.AbstractMap, java.util.Map, java.lang.Cloneable, java.io.Serializable):
  def __init__(self, initialCapacity: int, loadFactor: float) -> None: ...
  def __init__(self, initialCapacity: int) -> None: ...
  def __init__(self) -> None: ...
  def __init__(self, m: Map) -> None: ...
  def size(self) -> int: ...
  def isEmpty(self) -> bool: ...
  def get(self, key: Any) -> Any: ...
  def containsKey(self, key: Any) -> bool: ...
  def put(self, key: Any, value: Any) -> Any: ...
  def putAll(self, m: Map) -> None: ...
  def remove(self, key: Any) -> Any: ...
  def clear(self) -> None: ...
  def containsValue(self, value: Any) -> bool: ...
  def keySet(self) -> Set: ...
  def values(self) -> Collection: ...
  def entrySet(self) -> Set: ...
  def getOrDefault(self, key: Any, defaultValue: Any) -> Any: ...
  def putIfAbsent(self, key: Any, value: Any) -> Any: ...
  def remove(self, key: Any, value: Any) -> bool: ...
  def replace(self, key: Any, oldValue: Any, newValue: Any) -> bool: ...
  def replace(self, key: Any, value: Any) -> Any: ...
  def computeIfAbsent(self, key: Any, mappingFunction: Callable) -> Any: ...
  def computeIfPresent(self, key: Any, remappingFunction: Callable) -> Any: ...
  def compute(self, key: Any, remappingFunction: Callable) -> Any: ...
  def merge(self, key: Any, value: Any, remappingFunction: Callable) -> Any: ...
  def forEach(self, action: Callable) -> None: ...
  def replaceAll(self, function: Callable) -> None: ...
  def clone(self) -> Any: ...

jimbaker/jstubgen