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Heinz-Alexander Fuetterer ef6d475db3
Fix typos in docs and comments (#109619) 		2023-09-20 16:58:23 +00:00
..
README.md Update README for the cases generator (#107826) 2023-08-10 01:05:51 +00:00
_typing_backports.py gh-104504: cases generator: Add `--warn-unreachable` to the mypy config (#108112) 2023-08-21 00:40:41 +01:00
analysis.py gh-109287: Desugar inst(X) to op(X); macro(X) = X (#109294) 2023-09-15 08:39:05 -07:00
flags.py gh-107557: Remove unnecessary SAVE_IP instructions (#108583) 2023-08-29 16:51:51 +00:00
formatting.py gh-104504: Run mypy on cases_generator in CI (and blacken the code) (gh-108090) 2023-08-18 22:42:45 +09:00
generate_cases.py Fix typos in docs and comments (#109619) 2023-09-20 16:58:23 +00:00
instructions.py gh-109287: Desugar inst(X) to op(X); macro(X) = X (#109294) 2023-09-15 08:39:05 -07:00
interpreter_definition.md gh-106812: Small stack effect fixes (#107759) 2023-08-07 21:32:42 -07:00
lexer.py gh-104504: Run mypy on cases_generator in CI (and blacken the code) (gh-108090) 2023-08-18 22:42:45 +09:00
mypy.ini gh-104504: Cases generator: enable mypy's `possibly-undefined` error code (#108454) 2023-08-25 18:08:29 +01:00
parsing.py GH-108614: Add `RESUME_CHECK` instruction (GH-108630) 2023-09-07 14:39:03 +01:00
plexer.py gh-106812: Refactor cases_generator to allow uops with array stack effects (#107564) 2023-08-04 09:35:56 -07:00
stacking.py gh-109287: Desugar inst(X) to op(X); macro(X) = X (#109294) 2023-09-15 08:39:05 -07:00

README.md

Tooling to generate interpreters

Documentation for the instruction definitions in Python/bytecodes.c ("the DSL") is here.

What's currently here:

  • lexer.py: lexer for C, originally written by Mark Shannon
  • plexer.py: OO interface on top of lexer.py; main class: PLexer
  • parsing.py: Parser for instruction definition DSL; main class Parser
  • generate_cases.py: driver script to read Python/bytecodes.c and write Python/generated_cases.c.h (and several other files)
  • analysis.py: Analyzer class used to read the input files
  • flags.py: abstractions related to metadata flags for instructions
  • formatting.py: Formatter class used to write the output files
  • instructions.py: classes to analyze and write instructions
  • stacking.py: code to handle generalized stack effects

Note that there is some dummy C code at the top and bottom of Python/bytecodes.c to fool text editors like VS Code into believing this is valid C code.

A bit about the parser

The parser class uses a pretty standard recursive descent scheme, but with unlimited backtracking. The PLexer class tokenizes the entire input before parsing starts. We do not run the C preprocessor. Each parsing method returns either an AST node (a Node instance) or None, or raises SyntaxError (showing the error in the C source).

Most parsing methods are decorated with @contextual, which automatically resets the tokenizer input position when None is returned. Parsing methods may also raise SyntaxError, which is irrecoverable. When a parsing method returns None, it is possible that after backtracking a different parsing method returns a valid AST.

Neither the lexer nor the parsers are complete or fully correct. Most known issues are tersely indicated by # TODO: comments. We plan to fix issues as they become relevant.