[Python-Dev] ast-objects branch created

["Martin v. Löwis"]

I created

http://svn.python.org/projects/python/branches/ast-objects/

You can convert your repository to that branch with

svn switch svn+ssh://pythondev@svn.python.org/python/branches/ast-objects

in the toplevel directory. In particular, this features

http://svn.python.org/projects/python/branches/ast-objects/Parser/asdl_c.py
http://svn.python.org/projects/python/branches/ast-objects/Include/Python-ast.h
http://svn.python.org/projects/python/branches/ast-objects/Python/Python-ast.c

The status is currently this:
- asdl_c generates a type hierarchy: "Sum" productions have one type
   per constructor, inheriting from a type for the sum; plain products
   only have a type for the product.
- attributes are in the base type, accessible through o->_base.attr;
   projections of the product types are accessible directly through
   member names.
- all projections must be non-NULL. Sequences are represented through
   potentially empty lists; optional types are potentially represented
   through Py_None. bool is gone; use Py_True/Py_False. The only
   primitive type remaining is int (which only occurs in lineno)
- the types currently have only a constructor, a dealloc function,
   and an _Check macro.
- Naming is this: for cross-object-file visible symbols (functions
   and global variables), a Py_ prefix is used. Otherwise, I use
   the type name or constructor name directly. There is a #define
   for the Py_<type>_New function, so you can also write <type>(params).
   Parameter order for the types is: projections first, then
   attributes.
- For compatibility with the current code, the Sum base types
   also have the _kind enumeration (although that appears not
   to get initialized right now).

For asdl_c, I see the following things as TODOs:
- add support for traversing the types from C, through tp_members
   (read-only). Optionally add support for pickling.
- add support for garbage collection. I don't expect this to be
   necessary right now, but will be if the API is exposed, and it
   doesn't cost much.

The bigger chunk of necessary changes is in using these, starting
with ast.c.

Feel free to commit any changes to that branch that you consider
helpful. To avoid duplicated work, posting a note here might
also help.

Regards,
Martin