60 lines
1.6 KiB
Python
60 lines
1.6 KiB
Python
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from __future__ import annotations
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import ast
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import re
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from functools import lru_cache
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from typing import Any
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from typing_extensions import TypeAlias
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ActionParseResult: TypeAlias = "tuple[str, str, tuple[object, ...]]"
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"""An action is its name and the arbitrary tuple of its arguments."""
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class SkipAction(Exception):
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"""Raise in an action to skip the action (and allow any parent bindings to run)."""
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class ActionError(Exception):
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pass
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re_action_args = re.compile(r"([\w\.]+)\((.*)\)")
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@lru_cache(maxsize=1024)
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def parse(action: str) -> ActionParseResult:
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"""Parses an action string.
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Args:
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action: String containing action.
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Raises:
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ActionError: If the action has invalid syntax.
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Returns:
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Action name and arguments.
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"""
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args_match = re_action_args.match(action)
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if args_match is not None:
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action_name, action_args_str = args_match.groups()
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if action_args_str:
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try:
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# We wrap `action_args_str` to be able to disambiguate the cases where
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# the list of arguments is a comma-separated list of values from the
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# case where the argument is a single tuple.
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action_args: tuple[Any, ...] = ast.literal_eval(f"({action_args_str},)")
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except Exception:
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raise ActionError(
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f"unable to parse {action_args_str!r} in action {action!r}"
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)
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else:
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action_args = ()
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else:
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action_name = action
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action_args = ()
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namespace, _, action_name = action_name.rpartition(".")
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return namespace, action_name, action_args
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