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# orm/evaluator.py
# Copyright (C) 2005-2019 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
import operator
from .. import inspect
from .. import util
from ..sql import operators
class UnevaluatableError(Exception):
pass
_straight_ops = set(
getattr(operators, op)
for op in (
"add",
"mul",
"sub",
"div",
"mod",
"truediv",
"lt",
"le",
"ne",
"gt",
"ge",
"eq",
)
)
_notimplemented_ops = set(
getattr(operators, op)
for op in (
"like_op",
"notlike_op",
"ilike_op",
"notilike_op",
"between_op",
"in_op",
"notin_op",
"endswith_op",
"concat_op",
)
)
class EvaluatorCompiler(object):
def __init__(self, target_cls=None):
self.target_cls = target_cls
def process(self, clause):
meth = getattr(self, "visit_%s" % clause.__visit_name__, None)
if not meth:
raise UnevaluatableError(
"Cannot evaluate %s" % type(clause).__name__
)
return meth(clause)
def visit_grouping(self, clause):
return self.process(clause.element)
def visit_null(self, clause):
return lambda obj: None
def visit_false(self, clause):
return lambda obj: False
def visit_true(self, clause):
return lambda obj: True
def visit_column(self, clause):
if "parentmapper" in clause._annotations:
parentmapper = clause._annotations["parentmapper"]
if self.target_cls and not issubclass(
self.target_cls, parentmapper.class_
):
raise UnevaluatableError(
"Can't evaluate criteria against alternate class %s"
% parentmapper.class_
)
key = parentmapper._columntoproperty[clause].key
else:
key = clause.key
if (
self.target_cls
and key in inspect(self.target_cls).column_attrs
):
util.warn(
"Evaluating non-mapped column expression '%s' onto "
"ORM instances; this is a deprecated use case. Please "
"make use of the actual mapped columns in ORM-evaluated "
"UPDATE / DELETE expressions." % clause
)
else:
raise UnevaluatableError("Cannot evaluate column: %s" % clause)
get_corresponding_attr = operator.attrgetter(key)
return lambda obj: get_corresponding_attr(obj)
def visit_clauselist(self, clause):
evaluators = list(map(self.process, clause.clauses))
if clause.operator is operators.or_:
def evaluate(obj):
has_null = False
for sub_evaluate in evaluators:
value = sub_evaluate(obj)
if value:
return True
has_null = has_null or value is None
if has_null:
return None
return False
elif clause.operator is operators.and_:
def evaluate(obj):
for sub_evaluate in evaluators:
value = sub_evaluate(obj)
if not value:
if value is None:
return None
return False
return True
else:
raise UnevaluatableError(
"Cannot evaluate clauselist with operator %s" % clause.operator
)
return evaluate
def visit_binary(self, clause):
eval_left, eval_right = list(
map(self.process, [clause.left, clause.right])
)
operator = clause.operator
if operator is operators.is_:
def evaluate(obj):
return eval_left(obj) == eval_right(obj)
elif operator is operators.isnot:
def evaluate(obj):
return eval_left(obj) != eval_right(obj)
elif operator in _straight_ops:
def evaluate(obj):
left_val = eval_left(obj)
right_val = eval_right(obj)
if left_val is None or right_val is None:
return None
return operator(eval_left(obj), eval_right(obj))
else:
raise UnevaluatableError(
"Cannot evaluate %s with operator %s"
% (type(clause).__name__, clause.operator)
)
return evaluate
def visit_unary(self, clause):
eval_inner = self.process(clause.element)
if clause.operator is operators.inv:
def evaluate(obj):
value = eval_inner(obj)
if value is None:
return None
return not value
return evaluate
raise UnevaluatableError(
"Cannot evaluate %s with operator %s"
% (type(clause).__name__, clause.operator)
)
def visit_bindparam(self, clause):
if clause.callable:
val = clause.callable()
else:
val = clause.value
return lambda obj: val
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