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Deep union type-checking optimization.
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This commit optimizes away a superfluous expression in dynamically
generated code type-checking PEP 484- and 604-compliant unions
containing *no* unsubscripted types and thus containing *only*
subscripted type hints (e.g., `list[str] | set[bytes]`). Nobody asked
for this. Nonetheless, @leycec still delivers the sp33d. (*Son, a Sun!*)
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@leycec
leycec committed Apr 17, 2024
1 parent e408dc3 commit d473c1a
Showing 1 changed file with 65 additions and 55 deletions.
120 changes: 65 additions & 55 deletions beartype/_check/code/codemake.py
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Expand Up @@ -932,8 +932,29 @@ def _enqueue_hint_child(pith_child_expr: str) -> str:
# The subsequent call to the str.isidentifier() method is
# *MUCH* more expensive than this object identity test.
pith_curr_expr is VAR_NAME_PITH_ROOT or
# A simple Python identifier...
pith_curr_expr.isidentifier()
# A simple Python identifier *NOR*...
pith_curr_expr.isidentifier() or
# A complex Python expression already containing the
# assignment expression-specific "walrus" operator ":=".
# Since this implies this expression to already be an
# assignment expression, needlessly reassigning the local
# variable to which this assignment expression was
# previously assigned to yet another redundant local
# variable only harms efficiency for *NO* tangible gain
# (e.g., expanding the efficient assignment expression
# "__beartype_pith_1 := next(iter(__beartype_pith_0))" to
# the inefficient assignment expression
# "__beartype_pith_2 := __beartype_pith_1 :=
# next(iter(__beartype_pith_0))").
#
# Note that this edge case is induced by closure calls
# performed below of the form:
# _enqueue_hint_child(pith_curr_assign_expr)
#
# As of this writing, the only such edge case is a PEP 484-
# or 604-compliant union containing *ONLY* two or more
# PEP-compliant type hints (e.g., "list[str] | set[bytes]").
':=' in pith_curr_expr
):
# Then the current pith is safely assignable to a unique
# local variable via an assignment expression.
Expand Down Expand Up @@ -1199,22 +1220,21 @@ def _enqueue_hint_child(pith_child_expr: str) -> str:
# Python expression yielding the value of the
# current pith. Specifically...
pith_curr_expr=(
# If this union is subscripted by one or
# more PEP-compliant child hints, prefer
# If this union is also subscripted by one
# or more PEP-compliant child hints, prefer
# the expression assigning this value to a
# local variable efficiently reused by
# subsequent code generated for
# subsequent code generated for those
# PEP-compliant child hints.
pith_curr_assign_expr
if hint_childs_pep else
# Else, this union is *NOT* subscripted by
# one or more PEP-compliant child hints.
# Since this is the first and only test
# generated for this union, prefer the
# expression yielding the value of the
# current pith *WITHOUT* assigning this
# value to a local variable, which would
# otherwise pointlessly go unused.
# Else, this union is subscripted by *NO*
# PEP-compliant child hints. Since this is
# the first and only test generated for this
# union, prefer the expression yielding the
# value of the current pith *WITHOUT*
# assigning this value to a local variable,
# which would needlessly go unused.
pith_curr_expr
),
# Python expression evaluating to a tuple of
Expand Down Expand Up @@ -1250,52 +1270,42 @@ def _enqueue_hint_child(pith_child_expr: str) -> str:
# and append code type-checking this child hint.
for hint_child_index, hint_child in enumerate(
hint_childs_pep):
# If it is *NOT* the case that this union is subscripted
# by either...
if not (
# One or more PEP-noncompliant child hints *OR*...
hint_childs_nonpep or
# This is any PEP-compliant child hint *EXCEPT* the
# first...
hint_child_index
# Then prefer the expression efficiently reusing
# the value previously assigned to a local
# variable by either the above conditional or
# prior iteration of the current conditional;
):
# Then this union is both subscripted by no
# PEP-noncompliant child hints *AND* this is the first
# PEP-compliant child hint. In this case preface this
# code with an expression assigning this value to a
# local variable efficiently reused by code generated by
# subsequent iteration.
#
# Note this child hint is guaranteed to be followed by
# at least one more child hint. Why? Because the
# "typing" module forces unions to be subscripted by two
# or more child hints. By deduction, those child hints
# *MUST* be PEP-compliant. Ergo, we need *NOT*
# explicitly validate that constraint here.
# Code assigning the current pith expression.
func_curr_code += (
CODE_PEP572_PITH_ASSIGN_AND_format(
indent_curr=indent_curr,
pith_curr_assign_expr=pith_curr_assign_expr,
pith_curr_var_name=pith_curr_var_name,
))
# Else, this union is subscripted by either one or more
# PEP-noncompliant child hints *OR* this is any
# PEP-compliant child hint *EXCEPT* the first. In either
# case, prefer the expression efficiently reusing the
# value previously assigned to a local variable by
# either the above conditional or prior iteration of the
# current conditional.

# Code deeply type-checking this child hint.
func_curr_code += CODE_PEP484604_UNION_CHILD_PEP_format(
# Expression yielding the value of this pith.
hint_child_placeholder=_enqueue_hint_child(
pith_curr_var_name))
# If either...
#
# Then prefer the expression efficiently reusing
# the value previously assigned to a local
# variable by either the above conditional or
# prior iteration of the current conditional.
pith_curr_var_name
if (
# This union is also subscripted by one or
# more PEP-noncompliant child hints *OR*...
hint_childs_nonpep or
# This is any PEP-compliant child hint
# *EXCEPT* the first...
hint_child_index
) else
# Then this union is not subscripted by any
# PEP-noncompliant child hints *AND* this is the
# first PEP-compliant child hint. In this case,
# preface this code with an expression assigning
# this value to a local variable efficiently
# reused by code generated by subsequent
# iteration.
#
# Note this child hint is guaranteed to be
# followed by at least one more child hint. Why?
# Because the "typing" module forces unions to
# be subscripted by two or more child hints. By
# deduction, those child hints *MUST* be
# PEP-compliant. Ergo, we need *NOT* explicitly
# validate that constraint here.
pith_curr_assign_expr
))

# If this code is *NOT* its initial value, this union is
# subscripted by one or more unignorable child hints and
Expand Down

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