pythonnet/tools/geninterop/geninterop.py at master · pythonnet/pythonnet · GitHub

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#!/usr/bin/env uv run

# /// script

# dependencies = ["pycparser"]

# ///

"""

TypeOffset is a C# class that mirrors the in-memory layout of heap

allocated Python objects.

This script parses the Python C headers and outputs the TypeOffset

C# class.

Requirements:

- pycparser

- clang

"""

import os

import shutil

import sys

import sysconfig

import subprocess

from io import StringIO

from pathlib import Path

from pycparser import c_ast, c_parser

# rename some members from their C name when generating the C#

_typeoffset_member_renames = {

"ht_name": "name",

"ht_qualname": "qualname",

"getitem": "spec_cache_getitem",

}

def _check_output(*args, **kwargs):

return subprocess.check_output(*args, **kwargs, encoding="utf8")

class AstParser(object):

"""Walk an AST and determine the members of all structs"""

def __init__(self):

self._typedefs = {}

self._typedecls = {}

self._structs = {}

self._struct_stack = []

self._struct_members_stack = []

self._ptr_decl_depth = 0

self._struct_members = {}

self._decl_names = {}

def get_struct_members(self, name):

"""return a list of (name, type) of struct members"""

defs = self._typedefs.get(name)

if defs is None:

return None

node = self._get_leaf_node(defs)

name = node.name

if name is None:

name = defs.declname

return self._struct_members.get(name)

def visit(self, node):

if isinstance(node, c_ast.FileAST):

self.visit_ast(node)

elif isinstance(node, c_ast.Typedef):

self.visit_typedef(node)

elif isinstance(node, c_ast.TypeDecl):

self.visit_typedecl(node)

elif isinstance(node, c_ast.Struct):

self.visit_struct(node)

elif isinstance(node, c_ast.Decl):

self.visit_decl(node)

elif isinstance(node, c_ast.FuncDecl):

self.visit_funcdecl(node)

elif isinstance(node, c_ast.PtrDecl):

self.visit_ptrdecl(node)

elif isinstance(node, c_ast.IdentifierType):

self.visit_identifier(node)

elif isinstance(node, c_ast.Union):

self.visit_union(node)

def visit_ast(self, ast):

for _name, node in ast.children():

self.visit(node)

def visit_typedef(self, typedef):

self._typedefs[typedef.name] = typedef.type

self.visit(typedef.type)

def visit_typedecl(self, typedecl):

self._decl_names[typedecl.type] = typedecl.declname

self.visit(typedecl.type)

def visit_struct(self, struct):

if struct.decls:

self._structs[self._get_struct_name(struct)] = struct

# recurse into the struct

self._struct_stack.insert(0, struct)

for decl in struct.decls:

self._struct_members_stack.insert(0, decl.name)

self.visit(decl)

self._struct_members_stack.pop(0)

self._struct_stack.pop(0)

elif self._ptr_decl_depth or self._struct_members_stack:

# the struct is empty, but add it as a member to the current

# struct as the current member maybe a pointer to it.

self._add_struct_member(struct.name)

def visit_decl(self, decl):

self.visit(decl.type)

def visit_funcdecl(self, funcdecl):

self.visit(funcdecl.type)

def visit_ptrdecl(self, ptrdecl):

self._ptr_decl_depth += 1

self.visit(ptrdecl.type)

self._ptr_decl_depth -= 1

def visit_identifier(self, identifier):

type_name = " ".join(identifier.names)

self._add_struct_member(type_name)

def visit_union(self, union):

# Treat the field as if it was just the first declaration for now. This

# is not really correct, but handles the one case that is relevant for

# us right now (ob_refcnt being "split" in Python 3.12)

if self._struct_members_stack and union.decls:

decl = union.decls[0]

self._struct_members_stack.pop(0)

self._struct_members_stack.insert(0, decl.name)

self.visit(decl)

def _add_struct_member(self, type_name):

if not (self._struct_stack and self._struct_members_stack):

return

# add member to current struct

current_struct = self._struct_stack[0]

member_name = self._struct_members_stack[0]

struct_members = self._struct_members.setdefault(

self._get_struct_name(current_struct), []

)

# get the node associated with this type

node = None

if type_name in self._typedefs:

node = self._get_leaf_node(self._typedefs[type_name])

# If the struct was only declared when the typedef was created, its member

# information will not have been recorded and we have to look it up in the

# structs

if isinstance(node, c_ast.Struct) and node.decls is None:

if node.name in self._structs:

node = self._structs[node.name]

elif type_name in self._structs:

node = self._structs[type_name]

# If it's a struct (and not a pointer to a struct) expand

# it into the current struct definition

if not self._ptr_decl_depth and isinstance(node, c_ast.Struct):

for decl in node.decls or []:

self._struct_members_stack.insert(0, decl.name)

self.visit(decl)

self._struct_members_stack.pop(0)

else:

# otherwise add it as a single member

struct_members.append((member_name, type_name))

def _get_leaf_node(self, node):

if isinstance(node, c_ast.Typedef):

return self._get_leaf_node(node.type)

if isinstance(node, c_ast.TypeDecl):

return self._get_leaf_node(node.type)

return node

def _get_struct_name(self, node):

return node.name or self._decl_names.get(node) or "_struct_%d" % id(node)

class Writer(object):

def __init__(self):

self._stream = StringIO()

def append(self, indent=0, code=""):

self._stream.write("%s%s\n" % (indent * " ", code))

def extend(self, s):

self._stream.write(s)

def to_string(self):

return self._stream.getvalue()

def preprocess_python_headers(*, cc=None, include_py=None):

"""Return Python.h pre-processed, ready for parsing.

Requires clang.

"""

this_path = Path(__file__).parent

fake_libc_include = this_path / "fake_libc_include"

include_dirs = [fake_libc_include]

if cc is None:

cc = shutil.which("clang")

if cc is None:

cc = shutil.which("gcc")

if cc is None:

raise RuntimeError("No suitable C compiler found, need clang or gcc")

if include_py is None:

include_py = sysconfig.get_config_var("INCLUDEPY")

include_py = Path(include_py)

include_dirs.append(include_py)

include_args = [c for p in include_dirs for c in ["-I", str(p)]]

# fmt: off

defines = [

"-D", "__attribute__(x)=",

"-D", "__inline__=inline",

"-D", "__asm__=;#pragma asm",

"-D", "__int64=long long",

"-D", "_POSIX_THREADS",

]

if sys.platform == "win32":

defines.extend([

"-D", "__inline=inline",

"-D", "__ptr32=",

"-D", "__ptr64=",

"-D", "__declspec(x)=",

])

#fmt: on

if hasattr(sys, "abiflags"):

if "d" in sys.abiflags:

defines.extend(("-D", "PYTHON_WITH_PYDEBUG"))

if "u" in sys.abiflags:

defines.extend(("-D", "PYTHON_WITH_WIDE_UNICODE"))

python_h = include_py / "Python.h"

cmd = [cc, "-pthread"] + include_args + defines + ["-E", str(python_h)]

# normalize as the parser doesn't like windows line endings.

lines = []

for line in _check_output(cmd).splitlines():

if line.startswith("#"):

line = line.replace("\\", "/")

lines.append(line)

return "\n".join(lines)

def gen_interop_head(writer, version, abi_flags):

filename = os.path.basename(__file__)

class_definition = f"""

// Auto-generated by {filename}.

// DO NOT MODIFY BY HAND.

// Python {".".join(map(str, version[:2]))}: ABI flags: '{abi_flags}'

// ReSharper disable InconsistentNaming

// ReSharper disable IdentifierTypo

using System;

using System.Diagnostics.CodeAnalysis;

using System.Runtime.InteropServices;

using Python.Runtime.Native;

namespace Python.Runtime

{{"""

writer.extend(class_definition)

def gen_interop_tail(writer):

tail = """}

"""

writer.extend(tail)

def gen_heap_type_members(parser, writer, type_name):

"""Generate the TypeOffset C# class"""

members = parser.get_struct_members("PyHeapTypeObject")

class_definition = f"""

[SuppressMessage("Style", "IDE1006:Naming Styles",

Justification = "Following CPython",

Scope = "type")]

[StructLayout(LayoutKind.Sequential)]

internal class {type_name} : GeneratedTypeOffsets, ITypeOffsets

{{

public {type_name}() {{ }}

// Auto-generated from PyHeapTypeObject in Python.h

"""

# All the members are sizeof(void*) so we don't need to do any

# extra work to determine the size based on the type.

for name, _type in members:

name = _typeoffset_member_renames.get(name, name)

class_definition += " public int %s { get; private set; }\n" % name

class_definition += """ }

"""

writer.extend(class_definition)

def gen_structure_code(parser, writer, type_name, indent):

members = parser.get_struct_members(type_name)

if members is None:

return False

out = writer.append

out(indent, "[StructLayout(LayoutKind.Sequential)]")

out(indent, f"internal struct {type_name}")

out(indent, "{")

for name, _type in members:

out(indent + 1, f"public IntPtr {name};")

out(indent, "}")

out()

return True

def main(*, cc=None, include_py=None, version=None, out=None):

# preprocess Python.h and build the AST

python_h = preprocess_python_headers(cc=cc, include_py=include_py)

parser = c_parser.CParser()

ast = parser.parse(python_h)

# extract struct members from the AST

ast_parser = AstParser()

ast_parser.visit(ast)

writer = Writer()

if include_py and not version:

raise RuntimeError("If the include path is overridden, version must be "

"defined"

)

if version:

version = version.split('.')

else:

version = sys.version_info

# generate the C# code

abi_flags = getattr(sys, "abiflags", "").replace("m", "")

gen_interop_head(writer, version, abi_flags)

type_name = f"TypeOffset{version[0]}{version[1]}{abi_flags}"

gen_heap_type_members(ast_parser, writer, type_name)

gen_interop_tail(writer)

interop_cs = writer.to_string()

if not out or out == "-":

print(interop_cs)

else:

with open(out, "w") as fh:

fh.write(interop_cs)

if __name__ == "__main__":

import argparse

a = argparse.ArgumentParser("Interop file generator for Python.NET")

a.add_argument("--cc", help="C compiler to use, either clang or gcc")

a.add_argument("--include-py", help="Include path of Python")

a.add_argument("--version", help="Python version")

a.add_argument("--out", help="Output path", default="-")

args = a.parse_args()

sys.exit(main(

cc=args.cc,

include_py=args.include_py,

out=args.out,

version=args.version

))

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