/
preserve_defaults.py
126 lines (106 loc) · 4.62 KB
/
preserve_defaults.py
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"""Preserve function defaults.
Preserve the default argument values of function signatures in source code
and keep them not evaluated for readability.
"""
import ast
import inspect
import sys
from inspect import Parameter
from typing import Any, Dict, List, Optional
from sphinx.application import Sphinx
from sphinx.locale import __
from sphinx.pycode.ast import parse as ast_parse
from sphinx.pycode.ast import unparse as ast_unparse
from sphinx.util import logging
logger = logging.getLogger(__name__)
class DefaultValue:
def __init__(self, name: str) -> None:
self.name = name
def __repr__(self) -> str:
return self.name
def get_function_def(obj: Any) -> ast.FunctionDef:
"""Get FunctionDef object from living object.
This tries to parse original code for living object and returns
AST node for given *obj*.
"""
try:
source = inspect.getsource(obj)
if source.startswith((' ', r'\t')):
# subject is placed inside class or block. To read its docstring,
# this adds if-block before the declaration.
module = ast_parse('if True:\n' + source)
return module.body[0].body[0] # type: ignore
else:
module = ast_parse(source)
return module.body[0] # type: ignore
except (OSError, TypeError): # failed to load source code
return None
def get_default_value(lines: List[str], position: ast.AST) -> Optional[str]:
try:
if sys.version_info < (3, 8): # only for py38+
return None
elif position.lineno == position.end_lineno:
line = lines[position.lineno - 1]
return line[position.col_offset:position.end_col_offset]
else:
# multiline value is not supported now
return None
except (AttributeError, IndexError):
return None
def update_defvalue(app: Sphinx, obj: Any, bound_method: bool) -> None:
"""Update defvalue info of *obj* using type_comments."""
if not app.config.autodoc_preserve_defaults:
return
try:
lines = inspect.getsource(obj).splitlines()
if lines[0].startswith((' ', r'\t')):
lines.insert(0, '') # insert a dummy line to follow what get_function_def() does.
except (OSError, TypeError):
lines = []
try:
function = get_function_def(obj)
if function.args.defaults or function.args.kw_defaults:
sig = inspect.signature(obj)
defaults = list(function.args.defaults)
kw_defaults = list(function.args.kw_defaults)
parameters = list(sig.parameters.values())
for i, param in enumerate(parameters):
if param.default is param.empty:
if param.kind == param.KEYWORD_ONLY:
# Consume kw_defaults for kwonly args
kw_defaults.pop(0)
else:
if param.kind in (param.POSITIONAL_ONLY, param.POSITIONAL_OR_KEYWORD):
default = defaults.pop(0)
value = get_default_value(lines, default)
if value is None:
value = ast_unparse(default) # type: ignore
parameters[i] = param.replace(default=DefaultValue(value))
else:
default = kw_defaults.pop(0)
value = get_default_value(lines, default)
if value is None:
value = ast_unparse(default) # type: ignore
parameters[i] = param.replace(default=DefaultValue(value))
if bound_method and inspect.ismethod(obj):
# classmethods
cls = inspect.Parameter('cls', Parameter.POSITIONAL_OR_KEYWORD)
parameters.insert(0, cls)
sig = sig.replace(parameters=parameters)
if bound_method and inspect.ismethod(obj):
# classmethods can't be assigned __signature__ attribute.
obj.__dict__['__signature__'] = sig
else:
obj.__signature__ = sig
except (AttributeError, TypeError):
# failed to update signature (ex. built-in or extension types)
pass
except NotImplementedError as exc: # failed to ast.unparse()
logger.warning(__("Failed to parse a default argument value for %r: %s"), obj, exc)
def setup(app: Sphinx) -> Dict[str, Any]:
app.add_config_value('autodoc_preserve_defaults', False, True)
app.connect('autodoc-before-process-signature', update_defvalue)
return {
'version': '1.0',
'parallel_read_safe': True
}