105 lines
3.8 KiB
Python
105 lines
3.8 KiB
Python
import operator
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from sqlalchemy.sql import operators, functions
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from sqlalchemy.sql import expression as sql
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class UnevaluatableError(Exception):
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pass
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_straight_ops = set(getattr(operators, op)
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for op in ('add', 'mul', 'sub',
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# Py2K
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'div',
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# end Py2K
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'mod', 'truediv',
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'lt', 'le', 'ne', 'gt', 'ge', 'eq'))
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_notimplemented_ops = set(getattr(operators, op)
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for op in ('like_op', 'notlike_op', 'ilike_op',
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'notilike_op', 'between_op', 'in_op',
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'notin_op', 'endswith_op', 'concat_op'))
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class EvaluatorCompiler(object):
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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("Cannot evaluate %s" % type(clause).__name__)
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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_column(self, clause):
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if 'parentmapper' in clause._annotations:
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key = clause._annotations['parentmapper']._get_col_to_prop(clause).key
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else:
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key = clause.key
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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 = 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("Cannot evaluate clauselist with operator %s" % clause.operator)
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return evaluate
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def visit_binary(self, clause):
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eval_left,eval_right = map(self.process, [clause.left, clause.right])
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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("Cannot evaluate %s with operator %s" % (type(clause).__name__, clause.operator))
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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("Cannot evaluate %s with operator %s" % (type(clause).__name__, clause.operator))
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def visit_bindparam(self, clause):
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val = clause.value
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return lambda obj: val
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