Reiterables x 5.

This commit is the next in a commit chain deeply type-checking
**reiterables** (i.e., collections satisfying the
`collections.abc.Collection` protocol with guaranteed `O(1)` read-only
access to *only* the first collection item), en-route to *finally*
resolving feature request #167 kindly submitted by the perennial
brilliant @langfield (...*how I miss that awesome guy!*) several
lifetimes ago back when I was probably a wandering vagabond Buddhist
monk with a bad attitude, a begging bowl the size of my emaciated torso,
and an honestly pretty cool straw hat that glinted dangerously in the
firelight. Note that reiterables include *all* containers matched by one
or more of the following PEP 484- or 585-compliant type hints:

* `frozenset[...]`.
* `set[...]`.
* `collections.deque[...]`.
* `collections.abc.Collection[...]`.
* `collections.abc.KeysView[...]`.
* `collections.abc.MutableSet[...]`.
* `collections.abc.Set[...]`.
* `collections.abc.ValuesView[...]`.
* `typing.AbstractSet[...]`.
* `typing.Collection[...]`.
* `typing.Deque[...]`.
* `typing.FrozenSet[...]`.
* `typing.KeysView[...]`.
* `typing.MutableSet[...]`.
* `typing.Set[...]`.
* `typing.ValuesView[...]`.

Specifically, this commit continues reducing problematic DRY (Don't
Repeat Yourself) violations in @beartype's internal type-checking code
generator. (*Adriatic ranting on anti-fantastical aphantasia!*)

beartype/_check/code/codemake.py

@@ -1712,24 +1712,13 @@ def _enqueue_hint_child(pith_child_expr: str) -> str:
  #FIXME: This logic is an almost one-for-one copy of the
  #"hint_curr_sign in HINT_SIGNS_SEQUENCE_ARGS_1" block above.
  #Unify as follows:
- #* In the existing "datapepsigns" submodule:
- # * Refactor the get_hint_pep_sign() getter to assign *ALL*
- # fixed-length tuple type hints the "HintSignTupleFixed" sign
- # rather than the "HintSignTuple" sign.
- # * Refactor logic elsewhere to explicitly match
- # "HintSignTupleFixed" rather than matching "HintSignTuple"
- # and then attempting to disambiguate fixed-length tuple type
- # hints from that by inspecting for "Ellipses" singletons. In
- # theory, the only two places in the codebase this happens
- # *SHOULD* be:
- # * This submodule.
- # * Some "beartype.door" submodule specific to tuples.
  #* In the existing "codesnipstr" submodule:
  # * Define a new
  # "HINT_SIGN_TO_CODE_PEP484585_CONTAINER_ARGS_1_format"
  # dictionary global resembling:
  # # Initialized by the _init() function defined below.
- # HINT_SIGN_TO_CODE_PEP484585_CONTAINER_ARGS_1_format: Dict[HintSign, str] = {}
+ # HINT_SIGN_TO_CODE_PEP484585_CONTAINER_ARGS_1_format: (
+ # Dict[HintSign, Callable[..., str]]) = {}
  # def _init() -> None:
  # _CODE_PEP484585_COLLECTION_ARGS_1 = '''(
  # _{indent_curr} # True only if this pith is of this collection type *AND*...

beartype/_check/code/snip/codesnipstr.py

@@ -12,10 +12,15 @@
 '''
 
 # ....................{ IMPORTS }....................
+from beartype.typing import (
+ Callable,
+ Dict,
+)
 from beartype._check.checkmagic import (
  VAR_NAME_RANDOM_INT,
 )
-from collections.abc import Callable
+from beartype._data.hint.datahinttyping import CallableStrFormat
+from beartype._data.hint.pep.sign.datapepsigncls import HintSign
 
 # ....................{ HINT ~ placeholder : child }....................
 CODE_HINT_CHILD_PLACEHOLDER_PREFIX = '@['
@@ -142,6 +147,47 @@
 this parent type has been generated.
 '''
 
+# ....................{ HINT ~ pep : (484|585) : container }....................
+# Initialized by the _init() function defined below.
+HINT_SIGN_TO_CODE_PEP484585_CONTAINER_ARGS_1_format: (
+ Dict[HintSign, CallableStrFormat]) = {}
+'''
+Dictionary mapping from the sign uniquely identifying each applicable kind of
+**single-argument standard container type hint** (i.e., :pep:`484`- or
+:pep:`585`-compliant type hint describing a standard container, subscripted by
+exactly one child type hint constraining the type of *all* items residing in
+that container) to the :meth:`str.format` method bound to a code snippet
+type-checking the current pith against that kind of container.
+
+Caveats
+-------
+**Each such snippet must not contain ternary conditionals.** For unknown reasons
+suggesting a critical defect in the current implementation of Python 3.8's
+assignment expressions, this snippet raises :exc:`UnboundLocalError` exceptions
+resembling the following when this snippet contains one or more ternary
+conditionals:
+
+ UnboundLocalError: local variable '__beartype_pith_1' referenced before
+ assignment
+
+In particular, the initial draft of these snippets guarded against empty
+sequences with a seemingly reasonable ternary conditional:
+
+.. code-block:: python
+
+ CODE_PEP484585_SEQUENCE_ARGS_1 = \'\'\'(
+ {indent_curr} isinstance({pith_curr_assign_expr}, {hint_curr_expr}) and
+ {indent_curr} {hint_child_placeholder} if {pith_curr_var_name} else True
+ {indent_curr})\'\'\'
+
+That should behave as expected, but doesn't, presumably due to obscure scoping
+rules and a non-intuitive implementation of ternary conditionals in CPython.
+Ergo, the current version of this snippet guards against empty sequences with
+disjunctions and conjunctions (i.e., ``or`` and ``and`` operators) instead.
+Happily, the current version is more efficient than the equivalent approach
+based on ternary conditional (albeit slightly less intuitive).
+'''
+
 # ....................{ HINT ~ pep : (484|585) : mapping }....................
 CODE_PEP484585_MAPPING = '''(
 {indent_curr} # True only if this pith is of this mapping type *AND*...
@@ -583,57 +629,97 @@
 # ..................{ FORMATTERS }..................
 # str.format() methods, globalized to avoid inefficient dot lookups elsewhere.
 # This is an absurd micro-optimization. *fight me, github developer community*
-CODE_PEP484_INSTANCE_format: Callable = (
+CODE_PEP484_INSTANCE_format: CallableStrFormat = (
  CODE_PEP484_INSTANCE.format)
-CODE_PEP484585_GENERIC_CHILD_format: Callable = (
+CODE_PEP484585_GENERIC_CHILD_format: CallableStrFormat = (
  CODE_PEP484585_GENERIC_CHILD.format)
-CODE_PEP484585_MAPPING_format: Callable = (
+CODE_PEP484585_MAPPING_format: CallableStrFormat = (
  CODE_PEP484585_MAPPING.format)
-CODE_PEP484585_MAPPING_KEY_ONLY_format: Callable = (
+CODE_PEP484585_MAPPING_KEY_ONLY_format: CallableStrFormat = (
  CODE_PEP484585_MAPPING_KEY_ONLY.format)
-CODE_PEP484585_MAPPING_KEY_VALUE_format: Callable = (
+CODE_PEP484585_MAPPING_KEY_VALUE_format: CallableStrFormat = (
  CODE_PEP484585_MAPPING_KEY_VALUE.format)
-CODE_PEP484585_MAPPING_VALUE_ONLY_format: Callable = (
+CODE_PEP484585_MAPPING_VALUE_ONLY_format: CallableStrFormat = (
  CODE_PEP484585_MAPPING_VALUE_ONLY.format)
-CODE_PEP484585_MAPPING_KEY_ONLY_PITH_CHILD_EXPR_format: Callable = (
+CODE_PEP484585_MAPPING_KEY_ONLY_PITH_CHILD_EXPR_format: CallableStrFormat = (
  CODE_PEP484585_MAPPING_KEY_ONLY_PITH_CHILD_EXPR.format)
-CODE_PEP484585_MAPPING_VALUE_ONLY_PITH_CHILD_EXPR_format: Callable = (
+CODE_PEP484585_MAPPING_VALUE_ONLY_PITH_CHILD_EXPR_format: CallableStrFormat = (
  CODE_PEP484585_MAPPING_VALUE_ONLY_PITH_CHILD_EXPR.format)
-CODE_PEP484585_MAPPING_KEY_VALUE_PITH_CHILD_EXPR_format: Callable = (
+CODE_PEP484585_MAPPING_KEY_VALUE_PITH_CHILD_EXPR_format: CallableStrFormat = (
  CODE_PEP484585_MAPPING_KEY_VALUE_PITH_CHILD_EXPR.format)
-CODE_PEP484585_REITERABLE_ARGS_1_format: Callable = (
+CODE_PEP484585_REITERABLE_ARGS_1_format: CallableStrFormat = (
  CODE_PEP484585_REITERABLE_ARGS_1.format)
-CODE_PEP484585_REITERABLE_ARGS_1_PITH_CHILD_EXPR_format: Callable = (
+CODE_PEP484585_REITERABLE_ARGS_1_PITH_CHILD_EXPR_format: CallableStrFormat = (
  CODE_PEP484585_REITERABLE_ARGS_1_PITH_CHILD_EXPR.format)
-CODE_PEP484585_SEQUENCE_ARGS_1_format: Callable = (
+CODE_PEP484585_SEQUENCE_ARGS_1_format: CallableStrFormat = (
  CODE_PEP484585_SEQUENCE_ARGS_1.format)
-CODE_PEP484585_SEQUENCE_ARGS_1_PITH_CHILD_EXPR_format: Callable = (
+CODE_PEP484585_SEQUENCE_ARGS_1_PITH_CHILD_EXPR_format: CallableStrFormat = (
  CODE_PEP484585_SEQUENCE_ARGS_1_PITH_CHILD_EXPR.format)
-CODE_PEP484585_SUBCLASS_format: Callable = (
+CODE_PEP484585_SUBCLASS_format: CallableStrFormat = (
  CODE_PEP484585_SUBCLASS.format)
-CODE_PEP484585_TUPLE_FIXED_EMPTY_format: Callable = (
+CODE_PEP484585_TUPLE_FIXED_EMPTY_format: CallableStrFormat = (
  CODE_PEP484585_TUPLE_FIXED_EMPTY.format)
-CODE_PEP484585_TUPLE_FIXED_LEN_format: Callable = (
+CODE_PEP484585_TUPLE_FIXED_LEN_format: CallableStrFormat = (
  CODE_PEP484585_TUPLE_FIXED_LEN.format)
-CODE_PEP484585_TUPLE_FIXED_NONEMPTY_CHILD_format: Callable = (
+CODE_PEP484585_TUPLE_FIXED_NONEMPTY_CHILD_format: CallableStrFormat = (
  CODE_PEP484585_TUPLE_FIXED_NONEMPTY_CHILD.format)
-CODE_PEP484585_TUPLE_FIXED_NONEMPTY_PITH_CHILD_EXPR_format: Callable = (
+CODE_PEP484585_TUPLE_FIXED_NONEMPTY_PITH_CHILD_EXPR_format: CallableStrFormat = (
  CODE_PEP484585_TUPLE_FIXED_NONEMPTY_PITH_CHILD_EXPR.format)
-CODE_PEP484604_UNION_CHILD_PEP_format: Callable = (
+CODE_PEP484604_UNION_CHILD_PEP_format: CallableStrFormat = (
  CODE_PEP484604_UNION_CHILD_PEP.format)
-CODE_PEP484604_UNION_CHILD_NONPEP_format: Callable = (
+CODE_PEP484604_UNION_CHILD_NONPEP_format: CallableStrFormat = (
  CODE_PEP484604_UNION_CHILD_NONPEP.format)
-# CODE_PEP572_PITH_ASSIGN_AND_format: Callable = (
+# CODE_PEP572_PITH_ASSIGN_AND_format: CallableStrFormat = (
 # CODE_PEP572_PITH_ASSIGN_AND.format)
-CODE_PEP572_PITH_ASSIGN_EXPR_format: Callable = (
+CODE_PEP572_PITH_ASSIGN_EXPR_format: CallableStrFormat = (
  CODE_PEP572_PITH_ASSIGN_EXPR.format)
-CODE_PEP586_LITERAL_format: Callable = (
+CODE_PEP586_LITERAL_format: CallableStrFormat = (
  CODE_PEP586_LITERAL.format)
-CODE_PEP586_PREFIX_format: Callable = (
+CODE_PEP586_PREFIX_format: CallableStrFormat = (
  CODE_PEP586_PREFIX.format)
-CODE_PEP593_VALIDATOR_IS_format: Callable = (
+CODE_PEP593_VALIDATOR_IS_format: CallableStrFormat = (
  CODE_PEP593_VALIDATOR_IS.format)
-CODE_PEP593_VALIDATOR_METAHINT_format: Callable = (
+CODE_PEP593_VALIDATOR_METAHINT_format: CallableStrFormat = (
  CODE_PEP593_VALIDATOR_METAHINT.format)
-CODE_PEP593_VALIDATOR_SUFFIX_format: Callable = (
+CODE_PEP593_VALIDATOR_SUFFIX_format: CallableStrFormat = (
  CODE_PEP593_VALIDATOR_SUFFIX.format)
+
+# ..................{ PRIVATE ~ main }..................
+def _init() -> None:
+ '''
+ Initialize this submodule.
+ '''
+
+ # Defer function-specific imports.
+ from beartype._data.hint.pep.sign.datapepsignset import (
+ HINT_SIGNS_REITERABLE_ARGS_1,
+ HINT_SIGNS_SEQUENCE_ARGS_1,
+ )
+
+ # PEP 484- and 585-compliant code snippet generically type-checking the
+ # current pith against *any* arbitrary kind of single-argument standard
+ # container type hint.
+ _CODE_PEP484585_CONTAINER_ARGS_1 = '''(
+ _{indent_curr} # True only if this pith is of this container type *AND*...
+ _{indent_curr} isinstance({pith_curr_assign_expr}, {hint_curr_expr}) and
+ _{indent_curr} # True only if either this container is empty *OR* this container
+ _{indent_curr} # is both non-empty and the first item satisfies this hint.
+ _{indent_curr} (not {pith_curr_var_name} or {hint_child_placeholder})
+ _{indent_curr})'''
+
+ # str.format() method bound to this snippet.
+ _CODE_PEP484585_CONTAINER_ARGS_1_format = (
+ _CODE_PEP484585_CONTAINER_ARGS_1.format)
+
+ # For each sign identifying some kind of single-argument container hint...
+ for hint_sign in (
+ HINT_SIGNS_REITERABLE_ARGS_1 |
+ HINT_SIGNS_SEQUENCE_ARGS_1
+ ):
+ # Map this sign to this str.format() method.
+ HINT_SIGN_TO_CODE_PEP484585_CONTAINER_ARGS_1_format[
+ hint_sign] = _CODE_PEP484585_CONTAINER_ARGS_1_format
+
+
+# Initialize this submodule.
+_init()

beartype/_data/hint/datahinttyping.py

@@ -277,7 +277,7 @@
 argument accepted by the ``__getitem__` dunder method.
 '''
 
-# ....................{ CALLABLE ~ decor  }....................
+# ....................{ CALLABLE ~ decorator }....................
 BeartypeConfedDecorator = Callable[[BeartypeableT], BeartypeableT]
 '''
 PEP-compliant type hint matching a **configured beartype decorator** (i.e.,
@@ -294,6 +294,13 @@
 in both configuration and decoration modes.
 '''
 
+# ....................{ CALLABLE ~ decorator }....................
+CallableStrFormat = Callable[..., str]
+'''
+PEP-compliant type hint matching the signature of the standard
+:meth:`str.format` method.
+'''
+
 # ....................{ DICT }....................
 HintSignTrie = Dict[str, Union[HintSign, 'HintSignTrie']]
 '''