2df58dcd50
- Generalize the syntax for the type of a stack effect to allow a trailing `*`, so we can declare something as e.g. `PyCodeObject *`. - When generating assignments for stack effects, the type of the value on the stack should be the default (i.e., `PyObject *`) even when the variable copied to/from it has a different type, so that an appropriate cast is generated However, not when the variable is an array -- then the type is taken from the variable (as it is always `PyObject **`). |
||
|---|---|---|
| .. | ||
| analysis.py | ||
| flags.py | ||
| formatting.py | ||
| generate_cases.py | ||
| instructions.py | ||
| interpreter_definition.md | ||
| lexer.py | ||
| parsing.py | ||
| plexer.py | ||
| README.md | ||
| stacking.py | ||
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 Shannonplexer.py: OO interface on top of lexer.py; main class:PLexerparser.py: Parser for instruction definition DSL; main classParsergenerate_cases.py: driver script to readPython/bytecodes.cand writePython/generated_cases.c.h(and several other files)test_generator.py: tests, require manual running usingpytest
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.