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