plugin.core: Add type hints.

conservancy_beancount/_typing.py

@@ -0,0 +1,58 @@
+"""Type definitions for Conservancy Beancount code"""
+# Copyright © 2020  Brett Smith
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import abc
+import datetime
+
+import beancount.core.data as bc_data
+
+from typing import (
+    Any,
+    List,
+    NamedTuple,
+    Optional,
+    Set,
+    Tuple,
+    Type,
+)
+
+Account = bc_data.Account
+HookName = str
+MetaKey = str
+MetaValue = Any
+MetaValueEnum = str
+Posting = bc_data.Posting
+
+class LessComparable(metaclass=abc.ABCMeta):
+    @abc.abstractmethod
+    def __le__(self, other: Any) -> bool: ...
+
+    @abc.abstractmethod
+    def __lt__(self, other: Any) -> bool: ...
+
+
+class Directive(NamedTuple):
+    meta: bc_data.Meta
+    date: datetime.date
+
+
+class Transaction(Directive):
+    flag: bc_data.Flag
+    payee: Optional[str]
+    narration: str
+    tags: Set
+    links: Set
+    postings: List[Posting]

conservancy_beancount/plugin/core.py

@@ -19,14 +19,41 @@ import re
 
 from . import errors as errormod
 
+from typing import (
+    AbstractSet,
+    Any,
+    ClassVar,
+    Generic,
+    Iterable,
+    Iterator,
+    List,
+    Mapping,
+    Optional,
+    Tuple,
+    TypeVar,
+    Union,
+)
+from .._typing import (
+    Account,
+    HookName,
+    LessComparable,
+    MetaKey,
+    MetaValue,
+    MetaValueEnum,
+    Posting,
+    Transaction,
+)
+
 # I expect these will become configurable in the future, which is why I'm
 # keeping them outside of a class, but for now constants will do.
-DEFAULT_START_DATE = datetime.date(2020, 3, 1)
+DEFAULT_START_DATE: datetime.date = datetime.date(2020, 3, 1)
 # The default stop date leaves a little room after so it's easy to test
 # dates past the far end of the range.
-DEFAULT_STOP_DATE = datetime.date(datetime.MAXYEAR, 1, 1)
+DEFAULT_STOP_DATE: datetime.date = datetime.date(datetime.MAXYEAR, 1, 1)
 
-class _GenericRange:
+CT = TypeVar('CT', bound=LessComparable)
+
+class _GenericRange(Generic[CT]):
     """Convenience class to check whether a value is within a range.
 
     `foo in generic_range` is equivalent to `start <= foo < stop`.
@@ -35,17 +62,17 @@ class _GenericRange:
     makes it easier for subclasses to override.
     """
 
-    def __init__(self, start, stop):
+    def __init__(self, start: CT, stop: CT) -> None:
         self.start = start
         self.stop = stop
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return "{clsname}({self.start!r}, {self.stop!r})".format(
             clsname=type(self).__name__,
             self=self,
         )
 
-    def __contains__(self, item):
+    def __contains__(self, item: CT) -> bool:
         return self.start <= item < self.stop
 
 
@@ -57,7 +84,11 @@ class MetadataEnum:
     the primary values.
     """
 
-    def __init__(self, key, standard_values, aliases_map):
+    def __init__(self,
+                 key: MetaKey,
+                 standard_values: Iterable[MetaValueEnum],
+                 aliases_map: Mapping[MetaValueEnum, MetaValueEnum],
+    ) -> None:
         """Specify allowed values and aliases for this metadata.
 
         Arguments:
@@ -76,25 +107,28 @@ class MetadataEnum:
         self._aliases.update((v, v) for v in standard_values)
         assert self._stdvalues == set(self._aliases.values())
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return "{}<{}>".format(type(self).__name__, self.key)
 
-    def __contains__(self, key):
+    def __contains__(self, key: MetaValueEnum) -> bool:
         """Returns true if `key` is a standard value or alias."""
         return key in self._aliases
 
-    def __getitem__(self, key):
+    def __getitem__(self, key: MetaValueEnum) -> MetaValueEnum:
         """Return the standard value for `key`.
 
         Raises KeyError if `key` is not a known value or alias.
         """
         return self._aliases[key]
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[MetaValueEnum]:
         """Iterate over standard values."""
         return iter(self._stdvalues)
 
-    def get(self, key, default_key=None):
+    def get(self,
+            key: MetaValueEnum,
+            default_key: Optional[MetaValueEnum]=None,
+    ) -> Optional[MetaValueEnum]:
         """Return self[key], or a default fallback if that doesn't exist.
 
         default_key is another key to look up, *not* a default value to return.
@@ -121,18 +155,30 @@ class PostingChecker:
     # Subclasses may wish to override _default_value and _should_check.
     # See below.
 
-    HOOK_GROUPS = frozenset(['Posting', 'metadata'])
-    ACCOUNTS = ('',)
-    TXN_DATE_RANGE = _GenericRange(DEFAULT_START_DATE, DEFAULT_STOP_DATE)
-    VALUES_ENUM = {}
+    METADATA_KEY: ClassVar[MetaKey]
+    VALUES_ENUM: MetadataEnum
+    HOOK_GROUPS: AbstractSet[HookName] = frozenset(['Posting', 'metadata'])
+    ACCOUNTS: Union[str, Tuple[Account, ...]] = ('',)
+    TXN_DATE_RANGE: _GenericRange = _GenericRange(DEFAULT_START_DATE, DEFAULT_STOP_DATE)
 
-    def _meta_get(self, txn, post, key, default=None):
-        try:
+    def _meta_get(self,
+                  txn: Transaction,
+                  post: Posting,
+                  key: MetaKey,
+                  default: MetaValue=None,
+    ) -> MetaValue:
+        if post.meta and key in post.meta:
             return post.meta[key]
-        except (KeyError, TypeError):
+        else:
             return txn.meta.get(key, default)
 
-    def _meta_set(self, txn, post, post_index, key, value):
+    def _meta_set(self,
+                  txn: Transaction,
+                  post: Posting,
+                  post_index: int,
+                  key: MetaKey,
+                  value: MetaValue,
+    ) -> None:
         if post.meta is None:
             txn.postings[post_index] = Posting(*post[:5], {key: value})
         else:
@@ -142,22 +188,22 @@ class PostingChecker:
     # _default_value to get a default. This method should either return
     # a value string from METADATA_ENUM, or else raise InvalidMetadataError.
     # This base implementation does the latter.
-    def _default_value(self, txn, post):
+    def _default_value(self, txn: Transaction, post: Posting) -> MetaValueEnum:
         raise errormod.InvalidMetadataError(txn, post, self.METADATA_KEY)
 
     # The hook calls _should_check on every posting and only checks postings
     # when the method returns true. This base method checks the transaction
     # date is in TXN_DATE_RANGE, and the posting account name matches ACCOUNTS.
-    def _should_check(self, txn, post):
+    def _should_check(self, txn: Transaction, post: Posting) -> bool:
         ok = txn.date in self.TXN_DATE_RANGE
         if isinstance(self.ACCOUNTS, tuple):
             ok = ok and post.account.startswith(self.ACCOUNTS)
         else:
-            ok = ok and re.search(self.ACCOUNTS, post.account)
+            ok = ok and bool(re.search(self.ACCOUNTS, post.account))
         return ok
 
-    def run(self, txn, post):
-        errors = []
+    def run(self, txn: Transaction, post: Posting, post_index: int) -> Iterable[errormod._BaseError]:
+        errors: List[errormod._BaseError] = []
         if not self._should_check(txn, post):
             return errors
         source_value = self._meta_get(txn, post, self.METADATA_KEY)
@@ -175,5 +221,5 @@ class PostingChecker:
                     txn, post, self.METADATA_KEY, source_value,
                 ))
         if not errors:
-            self._meta_set(post, self.METADATA_KEY, set_value)
+            self._meta_set(txn, post, post_index, self.METADATA_KEY, set_value)
         return errors