837 lines
20 KiB
Python
837 lines
20 KiB
Python
# sql/operators.py
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# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <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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# 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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"""Defines operators used in SQL expressions."""
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from operator import (
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and_, or_, inv, add, mul, sub, mod, truediv, lt, le, ne, gt, ge, eq, neg,
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getitem, lshift, rshift
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)
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# Py2K
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from operator import (div,)
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# end Py2K
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from ..util import symbol
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class Operators(object):
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"""Base of comparison and logical operators.
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Implements base methods :meth:`operate` and :meth:`reverse_operate`,
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as well as :meth:`__and__`, :meth:`__or__`, :meth:`__invert__`.
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Usually is used via its most common subclass
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:class:`.ColumnOperators`.
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"""
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def __and__(self, other):
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"""Implement the ``&`` operator.
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When used with SQL expressions, results in an
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AND operation, equivalent to
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:func:`~.expression.and_`, that is::
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a & b
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is equivalent to::
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from sqlalchemy import and_
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and_(a, b)
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Care should be taken when using ``&`` regarding
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operator precedence; the ``&`` operator has the highest precedence.
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The operands should be enclosed in parenthesis if they contain
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further sub expressions::
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(a == 2) & (b == 4)
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"""
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return self.operate(and_, other)
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def __or__(self, other):
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"""Implement the ``|`` operator.
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When used with SQL expressions, results in an
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OR operation, equivalent to
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:func:`~.expression.or_`, that is::
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a | b
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is equivalent to::
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from sqlalchemy import or_
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or_(a, b)
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Care should be taken when using ``|`` regarding
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operator precedence; the ``|`` operator has the highest precedence.
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The operands should be enclosed in parenthesis if they contain
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further sub expressions::
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(a == 2) | (b == 4)
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"""
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return self.operate(or_, other)
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def __invert__(self):
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"""Implement the ``~`` operator.
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When used with SQL expressions, results in a
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NOT operation, equivalent to
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:func:`~.expression.not_`, that is::
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~a
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is equivalent to::
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from sqlalchemy import not_
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not_(a)
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"""
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return self.operate(inv)
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def op(self, opstring, precedence=0):
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"""produce a generic operator function.
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e.g.::
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somecolumn.op("*")(5)
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produces::
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somecolumn * 5
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This function can also be used to make bitwise operators explicit. For
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example::
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somecolumn.op('&')(0xff)
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is a bitwise AND of the value in ``somecolumn``.
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:param operator: a string which will be output as the infix operator
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between this element and the expression passed to the
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generated function.
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:param precedence: precedence to apply to the operator, when
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parenthesizing expressions. A lower number will cause the expression
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to be parenthesized when applied against another operator with
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higher precedence. The default value of ``0`` is lower than all
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operators except for the comma (``,``) and ``AS`` operators.
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A value of 100 will be higher or equal to all operators, and -100
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will be lower than or equal to all operators.
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.. versionadded:: 0.8 - added the 'precedence' argument.
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.. seealso::
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:ref:`types_operators`
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"""
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operator = custom_op(opstring, precedence)
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def against(other):
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return operator(self, other)
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return against
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def operate(self, op, *other, **kwargs):
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"""Operate on an argument.
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This is the lowest level of operation, raises
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:class:`NotImplementedError` by default.
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Overriding this on a subclass can allow common
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behavior to be applied to all operations.
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For example, overriding :class:`.ColumnOperators`
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to apply ``func.lower()`` to the left and right
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side::
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class MyComparator(ColumnOperators):
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def operate(self, op, other):
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return op(func.lower(self), func.lower(other))
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:param op: Operator callable.
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:param \*other: the 'other' side of the operation. Will
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be a single scalar for most operations.
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:param \**kwargs: modifiers. These may be passed by special
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operators such as :meth:`ColumnOperators.contains`.
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"""
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raise NotImplementedError(str(op))
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def reverse_operate(self, op, other, **kwargs):
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"""Reverse operate on an argument.
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Usage is the same as :meth:`operate`.
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"""
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raise NotImplementedError(str(op))
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class custom_op(object):
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"""Represent a 'custom' operator.
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:class:`.custom_op` is normally instantitated when the
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:meth:`.ColumnOperators.op` method is used to create a
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custom operator callable. The class can also be used directly
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when programmatically constructing expressions. E.g.
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to represent the "factorial" operation::
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from sqlalchemy.sql import UnaryExpression
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from sqlalchemy.sql import operators
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from sqlalchemy import Numeric
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unary = UnaryExpression(table.c.somecolumn,
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modifier=operators.custom_op("!"),
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type_=Numeric)
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"""
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__name__ = 'custom_op'
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def __init__(self, opstring, precedence=0):
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self.opstring = opstring
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self.precedence = precedence
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def __eq__(self, other):
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return isinstance(other, custom_op) and \
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other.opstring == self.opstring
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def __hash__(self):
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return id(self)
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def __call__(self, left, right, **kw):
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return left.operate(self, right, **kw)
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class ColumnOperators(Operators):
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"""Defines boolean, comparison, and other operators for
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:class:`.ColumnElement` expressions.
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By default, all methods call down to
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:meth:`.operate` or :meth:`.reverse_operate`,
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passing in the appropriate operator function from the
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Python builtin ``operator`` module or
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a SQLAlchemy-specific operator function from
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:mod:`sqlalchemy.expression.operators`. For example
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the ``__eq__`` function::
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def __eq__(self, other):
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return self.operate(operators.eq, other)
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Where ``operators.eq`` is essentially::
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def eq(a, b):
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return a == b
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The core column expression unit :class:`.ColumnElement`
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overrides :meth:`.Operators.operate` and others
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to return further :class:`.ColumnElement` constructs,
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so that the ``==`` operation above is replaced by a clause
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construct.
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See also:
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:ref:`types_operators`
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:attr:`.TypeEngine.comparator_factory`
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:class:`.ColumnOperators`
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:class:`.PropComparator`
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"""
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timetuple = None
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"""Hack, allows datetime objects to be compared on the LHS."""
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def __lt__(self, other):
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"""Implement the ``<`` operator.
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In a column context, produces the clause ``a < b``.
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"""
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return self.operate(lt, other)
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def __le__(self, other):
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"""Implement the ``<=`` operator.
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In a column context, produces the clause ``a <= b``.
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"""
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return self.operate(le, other)
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__hash__ = Operators.__hash__
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def __eq__(self, other):
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"""Implement the ``==`` operator.
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In a column context, produces the clause ``a = b``.
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If the target is ``None``, produces ``a IS NULL``.
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"""
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return self.operate(eq, other)
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def __ne__(self, other):
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"""Implement the ``!=`` operator.
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In a column context, produces the clause ``a != b``.
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If the target is ``None``, produces ``a IS NOT NULL``.
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"""
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return self.operate(ne, other)
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def __gt__(self, other):
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"""Implement the ``>`` operator.
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In a column context, produces the clause ``a > b``.
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"""
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return self.operate(gt, other)
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def __ge__(self, other):
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"""Implement the ``>=`` operator.
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In a column context, produces the clause ``a >= b``.
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"""
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return self.operate(ge, other)
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def __neg__(self):
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"""Implement the ``-`` operator.
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In a column context, produces the clause ``-a``.
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"""
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return self.operate(neg)
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def __getitem__(self, index):
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"""Implement the [] operator.
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This can be used by some database-specific types
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such as Postgresql ARRAY and HSTORE.
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"""
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return self.operate(getitem, index)
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def __lshift__(self, other):
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"""implement the << operator.
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Not used by SQLAlchemy core, this is provided
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for custom operator systems which want to use
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<< as an extension point.
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"""
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return self.operate(lshift, other)
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def __rshift__(self, other):
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"""implement the >> operator.
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Not used by SQLAlchemy core, this is provided
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for custom operator systems which want to use
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>> as an extension point.
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"""
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return self.operate(rshift, other)
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def concat(self, other):
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"""Implement the 'concat' operator.
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In a column context, produces the clause ``a || b``,
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or uses the ``concat()`` operator on MySQL.
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"""
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return self.operate(concat_op, other)
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def like(self, other, escape=None):
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"""Implement the ``like`` operator.
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In a column context, produces the clause ``a LIKE other``.
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E.g.::
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select([sometable]).where(sometable.c.column.like("%foobar%"))
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:param other: expression to be compared
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:param escape: optional escape character, renders the ``ESCAPE``
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keyword, e.g.::
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somecolumn.like("foo/%bar", escape="/")
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.. seealso::
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:meth:`.ColumnOperators.ilike`
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"""
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return self.operate(like_op, other, escape=escape)
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def ilike(self, other, escape=None):
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"""Implement the ``ilike`` operator.
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In a column context, produces the clause ``a ILIKE other``.
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E.g.::
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select([sometable]).where(sometable.c.column.ilike("%foobar%"))
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:param other: expression to be compared
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:param escape: optional escape character, renders the ``ESCAPE``
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keyword, e.g.::
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somecolumn.ilike("foo/%bar", escape="/")
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.. seealso::
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:meth:`.ColumnOperators.like`
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"""
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return self.operate(ilike_op, other, escape=escape)
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def in_(self, other):
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"""Implement the ``in`` operator.
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In a column context, produces the clause ``a IN other``.
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"other" may be a tuple/list of column expressions,
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or a :func:`~.expression.select` construct.
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"""
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return self.operate(in_op, other)
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def notin_(self, other):
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"""implement the ``NOT IN`` operator.
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This is equivalent to using negation with :meth:`.ColumnOperators.in_`,
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i.e. ``~x.in_(y)``.
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.. versionadded:: 0.8
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.. seealso::
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:meth:`.ColumnOperators.in_`
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"""
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return self.operate(notin_op, other)
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def notlike(self, other, escape=None):
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"""implement the ``NOT LIKE`` operator.
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This is equivalent to using negation with
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:meth:`.ColumnOperators.like`, i.e. ``~x.like(y)``.
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.. versionadded:: 0.8
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.. seealso::
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:meth:`.ColumnOperators.like`
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"""
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return self.operate(notlike_op, other, escape=escape)
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def notilike(self, other, escape=None):
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"""implement the ``NOT ILIKE`` operator.
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This is equivalent to using negation with
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:meth:`.ColumnOperators.ilike`, i.e. ``~x.ilike(y)``.
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.. versionadded:: 0.8
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.. seealso::
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:meth:`.ColumnOperators.ilike`
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"""
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return self.operate(notilike_op, other, escape=escape)
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def is_(self, other):
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"""Implement the ``IS`` operator.
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Normally, ``IS`` is generated automatically when comparing to a
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value of ``None``, which resolves to ``NULL``. However, explicit
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usage of ``IS`` may be desirable if comparing to boolean values
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on certain platforms.
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.. versionadded:: 0.7.9
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.. seealso:: :meth:`.ColumnOperators.isnot`
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"""
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return self.operate(is_, other)
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def isnot(self, other):
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"""Implement the ``IS NOT`` operator.
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Normally, ``IS NOT`` is generated automatically when comparing to a
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value of ``None``, which resolves to ``NULL``. However, explicit
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usage of ``IS NOT`` may be desirable if comparing to boolean values
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on certain platforms.
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.. versionadded:: 0.7.9
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.. seealso:: :meth:`.ColumnOperators.is_`
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"""
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return self.operate(isnot, other)
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def startswith(self, other, **kwargs):
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"""Implement the ``startwith`` operator.
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In a column context, produces the clause ``LIKE '<other>%'``
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"""
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return self.operate(startswith_op, other, **kwargs)
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def endswith(self, other, **kwargs):
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"""Implement the 'endswith' operator.
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In a column context, produces the clause ``LIKE '%<other>'``
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"""
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return self.operate(endswith_op, other, **kwargs)
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def contains(self, other, **kwargs):
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"""Implement the 'contains' operator.
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In a column context, produces the clause ``LIKE '%<other>%'``
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"""
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return self.operate(contains_op, other, **kwargs)
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def match(self, other, **kwargs):
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"""Implements the 'match' operator.
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In a column context, this produces a MATCH clause, i.e.
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``MATCH '<other>'``. The allowed contents of ``other``
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are database backend specific.
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"""
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return self.operate(match_op, other, **kwargs)
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def desc(self):
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"""Produce a :func:`~.expression.desc` clause against the
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parent object."""
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return self.operate(desc_op)
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def asc(self):
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"""Produce a :func:`~.expression.asc` clause against the
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parent object."""
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return self.operate(asc_op)
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def nullsfirst(self):
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"""Produce a :func:`~.expression.nullsfirst` clause against the
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parent object."""
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return self.operate(nullsfirst_op)
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def nullslast(self):
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"""Produce a :func:`~.expression.nullslast` clause against the
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parent object."""
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return self.operate(nullslast_op)
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def collate(self, collation):
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"""Produce a :func:`~.expression.collate` clause against
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the parent object, given the collation string."""
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return self.operate(collate, collation)
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def __radd__(self, other):
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"""Implement the ``+`` operator in reverse.
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See :meth:`.ColumnOperators.__add__`.
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"""
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return self.reverse_operate(add, other)
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def __rsub__(self, other):
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"""Implement the ``-`` operator in reverse.
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See :meth:`.ColumnOperators.__sub__`.
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"""
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return self.reverse_operate(sub, other)
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def __rmul__(self, other):
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"""Implement the ``*`` operator in reverse.
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See :meth:`.ColumnOperators.__mul__`.
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"""
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return self.reverse_operate(mul, other)
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def __rdiv__(self, other):
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"""Implement the ``/`` operator in reverse.
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See :meth:`.ColumnOperators.__div__`.
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"""
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return self.reverse_operate(div, other)
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def between(self, cleft, cright):
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"""Produce a :func:`~.expression.between` clause against
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the parent object, given the lower and upper range."""
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return self.operate(between_op, cleft, cright)
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def distinct(self):
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"""Produce a :func:`~.expression.distinct` clause against the
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parent object.
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"""
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return self.operate(distinct_op)
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def __add__(self, other):
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"""Implement the ``+`` operator.
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In a column context, produces the clause ``a + b``
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if the parent object has non-string affinity.
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If the parent object has a string affinity,
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produces the concatenation operator, ``a || b`` -
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see :meth:`.ColumnOperators.concat`.
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"""
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return self.operate(add, other)
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def __sub__(self, other):
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"""Implement the ``-`` operator.
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In a column context, produces the clause ``a - b``.
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"""
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return self.operate(sub, other)
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def __mul__(self, other):
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"""Implement the ``*`` operator.
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|
|
In a column context, produces the clause ``a * b``.
|
|
|
|
"""
|
|
return self.operate(mul, other)
|
|
|
|
def __div__(self, other):
|
|
"""Implement the ``/`` operator.
|
|
|
|
In a column context, produces the clause ``a / b``.
|
|
|
|
"""
|
|
return self.operate(div, other)
|
|
|
|
def __mod__(self, other):
|
|
"""Implement the ``%`` operator.
|
|
|
|
In a column context, produces the clause ``a % b``.
|
|
|
|
"""
|
|
return self.operate(mod, other)
|
|
|
|
def __truediv__(self, other):
|
|
"""Implement the ``//`` operator.
|
|
|
|
In a column context, produces the clause ``a / b``.
|
|
|
|
"""
|
|
return self.operate(truediv, other)
|
|
|
|
def __rtruediv__(self, other):
|
|
"""Implement the ``//`` operator in reverse.
|
|
|
|
See :meth:`.ColumnOperators.__truediv__`.
|
|
|
|
"""
|
|
return self.reverse_operate(truediv, other)
|
|
|
|
|
|
def from_():
|
|
raise NotImplementedError()
|
|
|
|
|
|
def as_():
|
|
raise NotImplementedError()
|
|
|
|
|
|
def exists():
|
|
raise NotImplementedError()
|
|
|
|
|
|
def is_(a, b):
|
|
return a.is_(b)
|
|
|
|
|
|
def isnot(a, b):
|
|
return a.isnot(b)
|
|
|
|
|
|
def collate(a, b):
|
|
return a.collate(b)
|
|
|
|
|
|
def op(a, opstring, b):
|
|
return a.op(opstring)(b)
|
|
|
|
|
|
def like_op(a, b, escape=None):
|
|
return a.like(b, escape=escape)
|
|
|
|
|
|
def notlike_op(a, b, escape=None):
|
|
return a.notlike(b, escape=escape)
|
|
|
|
|
|
def ilike_op(a, b, escape=None):
|
|
return a.ilike(b, escape=escape)
|
|
|
|
|
|
def notilike_op(a, b, escape=None):
|
|
return a.notilike(b, escape=escape)
|
|
|
|
|
|
def between_op(a, b, c):
|
|
return a.between(b, c)
|
|
|
|
|
|
def in_op(a, b):
|
|
return a.in_(b)
|
|
|
|
|
|
def notin_op(a, b):
|
|
return a.notin_(b)
|
|
|
|
|
|
def distinct_op(a):
|
|
return a.distinct()
|
|
|
|
|
|
def startswith_op(a, b, escape=None):
|
|
return a.startswith(b, escape=escape)
|
|
|
|
|
|
def notstartswith_op(a, b, escape=None):
|
|
return ~a.startswith(b, escape=escape)
|
|
|
|
|
|
def endswith_op(a, b, escape=None):
|
|
return a.endswith(b, escape=escape)
|
|
|
|
|
|
def notendswith_op(a, b, escape=None):
|
|
return ~a.endswith(b, escape=escape)
|
|
|
|
|
|
def contains_op(a, b, escape=None):
|
|
return a.contains(b, escape=escape)
|
|
|
|
|
|
def notcontains_op(a, b, escape=None):
|
|
return ~a.contains(b, escape=escape)
|
|
|
|
|
|
def match_op(a, b):
|
|
return a.match(b)
|
|
|
|
|
|
def comma_op(a, b):
|
|
raise NotImplementedError()
|
|
|
|
|
|
def concat_op(a, b):
|
|
return a.concat(b)
|
|
|
|
|
|
def desc_op(a):
|
|
return a.desc()
|
|
|
|
|
|
def asc_op(a):
|
|
return a.asc()
|
|
|
|
|
|
def nullsfirst_op(a):
|
|
return a.nullsfirst()
|
|
|
|
|
|
def nullslast_op(a):
|
|
return a.nullslast()
|
|
|
|
|
|
_commutative = set([eq, ne, add, mul])
|
|
|
|
_comparison = set([eq, ne, lt, gt, ge, le, between_op])
|
|
|
|
|
|
def is_comparison(op):
|
|
return op in _comparison
|
|
|
|
|
|
def is_commutative(op):
|
|
return op in _commutative
|
|
|
|
|
|
def is_ordering_modifier(op):
|
|
return op in (asc_op, desc_op,
|
|
nullsfirst_op, nullslast_op)
|
|
|
|
_associative = _commutative.union([concat_op, and_, or_])
|
|
|
|
_natural_self_precedent = _associative.union([getitem])
|
|
"""Operators where if we have (a op b) op c, we don't want to
|
|
parenthesize (a op b).
|
|
|
|
"""
|
|
|
|
_smallest = symbol('_smallest', canonical=-100)
|
|
_largest = symbol('_largest', canonical=100)
|
|
|
|
_PRECEDENCE = {
|
|
from_: 15,
|
|
getitem: 15,
|
|
mul: 8,
|
|
truediv: 8,
|
|
# Py2K
|
|
div: 8,
|
|
# end Py2K
|
|
mod: 8,
|
|
neg: 8,
|
|
add: 7,
|
|
sub: 7,
|
|
|
|
concat_op: 6,
|
|
match_op: 6,
|
|
|
|
ilike_op: 6,
|
|
notilike_op: 6,
|
|
like_op: 6,
|
|
notlike_op: 6,
|
|
in_op: 6,
|
|
notin_op: 6,
|
|
|
|
is_: 6,
|
|
isnot: 6,
|
|
|
|
eq: 5,
|
|
ne: 5,
|
|
gt: 5,
|
|
lt: 5,
|
|
ge: 5,
|
|
le: 5,
|
|
|
|
between_op: 5,
|
|
distinct_op: 5,
|
|
inv: 5,
|
|
and_: 3,
|
|
or_: 2,
|
|
comma_op: -1,
|
|
collate: 7,
|
|
as_: -1,
|
|
exists: 0,
|
|
_smallest: _smallest,
|
|
_largest: _largest
|
|
}
|
|
|
|
|
|
def is_precedent(operator, against):
|
|
if operator is against and operator in _natural_self_precedent:
|
|
return False
|
|
else:
|
|
return (_PRECEDENCE.get(operator,
|
|
getattr(operator, 'precedence', _smallest)) <=
|
|
_PRECEDENCE.get(against,
|
|
getattr(against, 'precedence', _largest)))
|