hammurabi/law.py
"""
This module contains the definition of Law which is responsible for
the execution of its registered Rules. Every Law can have multiple rules to execute.
In case a rule raises an exception the execution may abort and none of
the remaining rules will be executed neither pipes or children. An abort
can cause an inconsistent state or a dirty git branch. If ``rule_can_abort``
config is set to True, the whole execution of the :class:``hammurabi.pillar.Pillar``
will be aborted and the original exception will be re-raised.
"""
import logging
from typing import Iterable, List, Tuple, Union
from hammurabi.config import config
from hammurabi.exceptions import AbortLawError, PreconditionFailedError
from hammurabi.helpers import full_strip
from hammurabi.mixins import GitMixin
from hammurabi.rules.base import Precondition, Rule
class Law(GitMixin):
"""
A Law is a collection of Rules which is responsible for the rule execution
and git committing.
Example usage:
.. code-block:: python
>>> from pathlib import Path
>>> from hammurabi import Law, Pillar, FileExists
>>>
>>> example_law = Law(
>>> name="Name of the law",
>>> description="Well detailed description what this law does.",
>>> rules=(
>>> FileExists(
>>> name="Create pyproject.toml",
>>> path=Path("./pyproject.toml")
>>> ),
>>> )
>>> )
>>>
>>> pillar = Pillar()
>>> pillar.register(example_law)
"""
def __init__(
self,
name: str,
description: str,
rules: Iterable[Rule],
preconditions: Iterable[Precondition] = (),
) -> None:
"""
:param name: Name of the law
:type name: str
:param description: Detailed description what kind of rules are included
:type description: str
:param rules: List of those rules which should be included in the law
:type rules: Iterable[Rule]
"""
super().__init__()
self.name = name.strip()
self.description = full_strip(description)
self.rules: Iterable[Rule] = tuple()
self.preconditions = preconditions
self._failed_rules: Tuple[Rule, ...] = tuple()
for rule in rules:
self.rules += (rule,)
def __repr__(self) -> str:
return (
"Law("
f'name="{self.name}", '
f'description="{self.description}", '
f"rules={self.rules}, "
f"preconditions={self.preconditions})"
)
def __str__(self) -> str:
return f"{self.name} law"
@property
def passed_rules(self) -> Tuple[Rule, ...]:
"""
Return the rules which did modifications and not failed.
:return: Return the passed rules
:rtype: Tuple[Rule, ...]
"""
return tuple(r for r in self.rules if r.made_changes)
@property
def failed_rules(self) -> Tuple[Rule, ...]:
"""
Return the rules which did modifications and failed.
:return: Return the failed rules
:rtype: Union[Tuple[()], Tuple[Rule]]
"""
return self._failed_rules
@property
def skipped_rules(self) -> Tuple[Rule, ...]:
"""
Return the rules which neither modified the code nor failed.
:return: Return the skipped rules
:rtype: Tuple[Rule, ...]
"""
def is_skipped(rule) -> bool:
"""
Return the evaluation if the rule is skipped or not.
:return: Evaluation if the rule is skipped
:rtype: bool
"""
not_passed = rule not in self.passed_rules
not_failed = rule not in self.failed_rules
return not_passed and not_failed
return tuple(r for r in self.rules if is_skipped(r))
@property
def documentation(self) -> str:
"""
Get the name and description of the Law object.
:return: Return the name and description of the law as its documentation
:rtype: str
"""
return f"{self.name}\n{self.description}"
@property
def can_proceed(self) -> bool:
"""
Evaluate if the execution can be continued. If preconditions are set,
those will be evaluated by this method.
:return: Return with the result of evaluation
:rtype: bool
.. warning::
:func:`hammurabi.rules.base.Rule.can_proceed` checks the result of
``self.preconditions``, which means the preconditions are executed.
Make sure that you are not doing any modifications within rules used
as preconditions, otherwise take extra attention for those rules.
"""
logging.debug('Checking if "%s" can proceed with execution', self.name)
return all([condition.execute() for condition in self.preconditions])
def get_execution_order(self) -> List[Union[Rule, Precondition]]:
"""
Get the execution order of the registered rules. The order will
contain the pipes and children as well.
This helper function is useful in debugging and information
gathering.
:return: Return the execution order of the rules
:rtype: List[Rule]
"""
order: List[Union[Rule, Precondition]] = list()
for rule in self.rules:
order.extend(rule.get_execution_order())
return order
def commit(self) -> None:
"""
Commit the changes made by registered rules and add a
meaningful commit message.
Example commit message:
.. code-block:: text
Migrate to next generation project template
* Create pyproject.toml
* Add meta info from setup.py to pyproject.toml
* Add existing dependencies
* Remove requirements.txt
* Remove setup.py
"""
if not self.passed_rules:
return
order = self.get_execution_order()
rules = [f"* {rule.name}" for rule in order if rule.made_changes]
rules_commit_message = "\n".join(rules)
self.git_commit(f"{self.documentation}\n\n{rules_commit_message}")
@staticmethod
def __execute_rule_chain(rule: Rule) -> None:
"""
Execute the given rule. In case of an exception, the execution of rules
will continue except the failing one. The failed rule's pipe and children
will not be executed.
:param rule: A registered rule
:type rule: Rule
:raises: ``AbortLawError``
"""
try:
rule.execute()
except PreconditionFailedError:
logging.warning(
'Cancelling execution of "%s", the preconditions are not fulfilled',
rule.name,
)
except Exception as exc: # pylint: disable=broad-except
logging.error('Execution of "%s" is aborted: %s', rule.name, str(exc))
chained_rules = filter(
lambda r: isinstance(r, Rule), rule.get_rule_chain(rule)
)
for chain in chained_rules:
logging.error('Due to errors "%s" is aborted', chain.name)
raise AbortLawError(str(exc)) from exc
def __execute_rule(self, rule: Rule) -> None:
"""
Execute a rule registered for the law. In case of an exception the
exception will be re-raised.
"""
try:
self.__execute_rule_chain(rule)
except AbortLawError as exc:
logging.error(str(exc))
self._failed_rules += (rule,)
if config.settings.rule_can_abort:
raise exc
def enforce(self) -> None:
"""
Execute all registered rule. If ``rule_can_abort`` config option
is set to ``True``, all the rules will be aborted and an exception
will be raised.
When the whole execution chain is finished, the changes will be
committed except the failed ones.
.. note::
Failed rules and their chain (excluding prerequisites) will be added
to the pull request description.
:raises: ``AbortLawError``
"""
if not self.can_proceed:
logging.warning(
'Cancelling execution of "%s", the preconditions are not fulfilled',
self.name,
)
return
logging.info('Executing law "%s"', self.name)
for rule in self.rules:
self.__execute_rule(rule)
logging.info('Committing changes made by "%s"', self.name)
self.commit()