Zephyr ASDL

This directory contains an implementation of Zephyr ASDL. It consists of these components:

• asdl.py: the ASDL schema parser, borrowed from Python (Python-3.5.2/Parser/asdl.py)
• py_meta.py: library to dynamically generate Python classes (using metaclasses)
• encode.py: library to encode ASDL data structures in oheap format (to be described later)
• gen_cpp.py: tool to generate C++ code to read the oheap format

This library will be used for serializing parsed osh and oil code.

The files arith_parse.py, arith.asdl, arith_ast.py, and arith_demo.cc are an end-to-end demo, driven by run.sh.

For more on Zephyr ASDL, see this blog post.

OHeap

This is an experimental serialization of ASDL data structures. See What is OHeap?

On Ubuntu:

build/codegen.sh download-clang     
build/codegen.sh extract-clang     

# encodes and decodes arithmetic AST
asdl/run.sh asdl-arith-oheap

# encodes and decodes the OSH "lossless syntax tree"
asdl/run.sh osh-demo

(NOTE: We probably shouldn't require Clang for this? It's only necessary for ASAN, clang-format, build time benchmarking, runtime benchmarking vs. GCC, etc.)

OHeap Use Cases:

• To freeze OSH LSTs (instances of types in osh.asdl)
  • This isn't necessary if the parser is fast enough (which is desirable)
• To freeze Python / OPy bytecode, and associated constants
  • Special case: ASDL reflection data for osh.asdl, so we can pretty print them