Source code for symforce.python_util

# ----------------------------------------------------------------------------
# SymForce - Copyright 2022, Skydio, Inc.
# This source code is under the Apache 2.0 license found in the LICENSE file.
# ----------------------------------------------------------------------------

General python utilities.
import functools
import inspect
import os
import random
import re
import shutil
import string
import subprocess
from pathlib import Path

from symforce import logger
from symforce import typing as T

[docs]def remove_if_exists(path: Path) -> None: """ Delete a file or directory if it exists. """ if not path.exists(): logger.debug(f"Doesn't exist: {path}") return elif path.is_dir(): logger.debug(f"Removing directory: {path}") shutil.rmtree(path) else: logger.debug(f"Removing file: {path}") path.unlink()
[docs]def execute_subprocess( cmd: T.Union[str, T.Sequence[str]], stdin_data: T.Optional[str] = None, log_stdout: bool = True, log_stdout_to_error_on_error: bool = True, **kwargs: T.Any, ) -> str: """ Execute subprocess and log command as well as stdout/stderr. Args: stdin_data (bytes): Data to pass to stdin log_stdout (bool): Write process stdout to the logger? log_stdout_to_error_on_error: Write output to logger.error if the command fails? Raises: subprocess.CalledProcessError: If the return code is nonzero """ if stdin_data is not None: stdin_data_encoded = stdin_data.encode("utf-8") else: stdin_data_encoded = bytes() cmd_str = " ".join(cmd) if isinstance(cmd, (tuple, list)) else cmd logger.debug(f"Subprocess: {cmd_str}") with subprocess.Popen( cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, **kwargs ) as proc: (stdout, _) = proc.communicate(stdin_data_encoded) return_code = proc.returncode going_to_log_to_err = return_code != 0 and log_stdout_to_error_on_error stdout_decoded = stdout.decode("utf-8") if stdout_decoded and log_stdout and not going_to_log_to_err: if going_to_log_to_err: logger.error( f"Subprocess {cmd} exited with code: {return_code}. Output:\n{stdout_decoded}" ) if return_code != 0: raise subprocess.CalledProcessError(return_code, cmd, stdout_decoded) return stdout_decoded
[docs]def camelcase_to_snakecase(s: str) -> str: """ Convert CamelCase -> snake_case. """ return re.sub(r"(?<!^)(?=[A-Z][a-z])", "_", s).lower()
[docs]def snakecase_to_camelcase(s: str) -> str: """ Convert snake_case -> CamelCase Double underscores are escaped, e.g. one__two becomes One_Two """ return ( re.sub("_+", lambda match: "_" * (len( // 2) + " ", s) .title() .replace(" ", "") )
[docs]def camelcase_to_screaming_snakecase(s: str) -> str: """ Convert CamelCase -> SCREAMING_SNAKE_CASE """ return camelcase_to_snakecase(s).upper()
[docs]def str_replace_all(s: str, replacements: T.Dict[str, str]) -> str: """ Call ``str.replace(old, new)`` for every pair (old, new) in replacements """ for old, new in replacements.items(): s = s.replace(old, new) return s
[docs]def str_removeprefix(s: str, prefix: str) -> str: """ Backport of ``str.removeprefix``, from Python3.9 If the string starts with the prefix string and that prefix is not empty, return ``string[len(prefix):]``. Otherwise, return a copy of the original string. """ if s.startswith(prefix): return s[len(prefix) :] else: return s
[docs]def str_removesuffix(s: str, suffix: str) -> str: """ Backport of ``str.removesuffix``, from Python3.9 If the string ends with the suffix string and that suffix is not empty, return ``string[:-len(suffix)]``. Otherwise, return a copy of the original string. """ if s.endswith(suffix): return s[: -len(suffix)] else: return s
[docs]def dots_and_brackets_to_underscores(s: str) -> str: """ Converts all ``.`` and ``[]`` in the given string to underscores such that the resulting string is a valid/readable variable name. """ leading_trailing_dots_and_brackets_regex = re.compile(r"^[\.\[\]]+|[\.\[\]]+$") dots_and_brackets_regex = re.compile(r"[\.\[\]]+") return re.sub( dots_and_brackets_regex, "_", re.sub(leading_trailing_dots_and_brackets_regex, "", s), )
[docs]def files_in_dir(dirname: T.Openable, relative: bool = False) -> T.Iterator[str]: """ Return a list of files in the given directory. """ for root, _, filenames in os.walk(os.fspath(dirname)): for filename in filenames: abspath = os.path.join(root, filename) if relative: yield os.path.relpath(abspath, dirname) else: yield abspath
[docs]def id_generator(size: int = 6, chars: str = string.ascii_uppercase + string.digits) -> str: """ Generate a random string within a character set - for example ``"6U1S75"``. This is not cryptographically secure. """ return "".join(random.choice(chars) for _ in range(size))
[docs]def getattr_recursive(obj: object, attrs: T.Sequence[str]) -> T.Any: """ Recursively calls getattr on obj with the attributes in attrs and returns the output. If attr is empty, returns obj. Example:: get_attr_recursive(obj, ["A", "B", "C"]) returns the same thing as: obj.A.B.C """ return getattr_recursive(getattr(obj, attrs[0]), attrs[1:]) if len(attrs) else obj
[docs]class InvalidKeyError(ValueError): pass
[docs]class InvalidPythonIdentifierError(InvalidKeyError): pass
[docs]def base_and_indices(indexed_array: str) -> T.Tuple[str, T.List[int]]: r""" Decomposes indexed_array into ``(base, indices)`` in the sense that, ``"arr[1][2]" -> ("arr", [1, 2])``. ``base`` is the initial substring of ``indexed_array`` that does not contain either ``[`` or ``]``; ``indices`` is the list of integer indices indexing into the array denoted by ``base``. ``indices`` will be the empty list if ``indexed_array`` has no indices. Raises: InvalidKeyError: if ``indexed_array`` is not matched by the regular expression ``r"[\[\]]*(\[[0-9]+\])*"``, i.e., is not a string with no square brackets, followed by 0 or more integers wrapped in square brackets. Example: >>> assert ("arr", []) == base_and_indices("arr") >>> assert ("arr", [1, 2, 3]) == base_and_indices("arr[1][2][3]") >>> try: >>> base_and_indices("arr[1].bad[2]") >>> assert False >>> except ValueError: >>> pass >>> except: >>> assert False """ base_indices_match = re.fullmatch(r"([^\[\]]*)((?:\[[0-9]+\])*)", indexed_array) if base_indices_match is None: raise InvalidKeyError(f"{indexed_array} is not a base and its indices") base, indices_str = base_indices_match.groups() indices = [int( for match in re.finditer(r"[0-9]+", indices_str)] return base, indices
[docs]def plural(singular: str, count: int, plural: str = None) -> str: """ Return the singular or plural form of a word based on count Adds an s to singular by default for the plural form, or uses ``plural`` if provided """ if count == 1: return singular else: return plural or (singular + "s")
[docs]def get_func_from_maybe_bound_function(func: T.Callable) -> T.Callable: """ Get the original function, from a function possibly bound by ``functools.partial`` """ if isinstance(func, functools.partial): return func.func else: return func
[docs]def get_class_for_method(func: T.Callable) -> T.Type: """ Get the class from an instance method ``func`` See """ if isinstance(func, functools.partial): return get_class_for_method(func.func) if inspect.ismethod(func) or ( inspect.isbuiltin(func) and getattr(func, "__self__", None) is not None and getattr(getattr(func, "__self__"), "__class__", None) is not None ): return getattr(getattr(func, "__self__"), "__class__") if inspect.isfunction(func): cls = getattr( inspect.getmodule(func), func.__qualname__.split(".<locals>", 1)[0].rsplit(".", 1)[0], None, ) if isinstance(cls, type): return cls return getattr(func, "__objclass__") # handle special descriptor objects
[docs]class AttrDict(dict): """ A simple attr-dict, i.e. a dictionary whose keys are also accessible directly as fields Based on """ def __init__(self, **kwargs: T.Any) -> None: super().__init__(**kwargs) self.__dict__ = self if T.TYPE_CHECKING: # The existence of these methods makes mypy happy with accessing members of this object, # since it isn't quite able to figure out how __dict__ works. # Note that this code has no effect at runtime because T.TYPE_CHECKING evaluates to False, # so this code never runs and these methods are not defined. def __getattr__(self, name: str) -> T.Any: pass def __setattr__(self, name: str, value: T.Any) -> None: pass