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# sql/operators.py
# Copyright (C) 2005-2016 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
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Defines operators used in SQL expressions."""
from .. import util
from operator import (
and_, or_, inv, add, mul, sub, mod, truediv, lt, le, ne, gt, ge, eq, neg,
getitem, lshift, rshift, contains
)
if util.py2k:
from operator import div
else:
div = truediv
class Operators(object):
"""Base of comparison and logical operators.
Implements base methods
:meth:`~sqlalchemy.sql.operators.Operators.operate` and
:meth:`~sqlalchemy.sql.operators.Operators.reverse_operate`, as well as
:meth:`~sqlalchemy.sql.operators.Operators.__and__`,
:meth:`~sqlalchemy.sql.operators.Operators.__or__`,
:meth:`~sqlalchemy.sql.operators.Operators.__invert__`.
Usually is used via its most common subclass
:class:`.ColumnOperators`.
"""
__slots__ = ()
def __and__(self, other):
"""Implement the ``&`` operator.
When used with SQL expressions, results in an
AND operation, equivalent to
:func:`~.expression.and_`, that is::
a & b
is equivalent to::
from sqlalchemy import and_
and_(a, b)
Care should be taken when using ``&`` regarding
operator precedence; the ``&`` operator has the highest precedence.
The operands should be enclosed in parenthesis if they contain
further sub expressions::
(a == 2) & (b == 4)
"""
return self.operate(and_, other)
def __or__(self, other):
"""Implement the ``|`` operator.
When used with SQL expressions, results in an
OR operation, equivalent to
:func:`~.expression.or_`, that is::
a | b
is equivalent to::
from sqlalchemy import or_
or_(a, b)
Care should be taken when using ``|`` regarding
operator precedence; the ``|`` operator has the highest precedence.
The operands should be enclosed in parenthesis if they contain
further sub expressions::
(a == 2) | (b == 4)
"""
return self.operate(or_, other)
def __invert__(self):
"""Implement the ``~`` operator.
When used with SQL expressions, results in a
NOT operation, equivalent to
:func:`~.expression.not_`, that is::
~a
is equivalent to::
from sqlalchemy import not_
not_(a)
"""
return self.operate(inv)
def op(self, opstring, precedence=0, is_comparison=False):
"""produce a generic operator function.
e.g.::
somecolumn.op("*")(5)
produces::
somecolumn * 5
This function can also be used to make bitwise operators explicit. For
example::
somecolumn.op('&')(0xff)
is a bitwise AND of the value in ``somecolumn``.
:param operator: a string which will be output as the infix operator
between this element and the expression passed to the
generated function.
:param precedence: precedence to apply to the operator, when
parenthesizing expressions. A lower number will cause the expression
to be parenthesized when applied against another operator with
higher precedence. The default value of ``0`` is lower than all
operators except for the comma (``,``) and ``AS`` operators.
A value of 100 will be higher or equal to all operators, and -100
will be lower than or equal to all operators.
.. versionadded:: 0.8 - added the 'precedence' argument.
:param is_comparison: if True, the operator will be considered as a
"comparison" operator, that is which evaluates to a boolean
true/false value, like ``==``, ``>``, etc. This flag should be set
so that ORM relationships can establish that the operator is a
comparison operator when used in a custom join condition.
.. versionadded:: 0.9.2 - added the
:paramref:`.Operators.op.is_comparison` flag.
.. seealso::
:ref:`types_operators`
:ref:`relationship_custom_operator`
"""
operator = custom_op(opstring, precedence, is_comparison)
def against(other):
return operator(self, other)
return against
def operate(self, op, *other, **kwargs):
"""Operate on an argument.
This is the lowest level of operation, raises
:class:`NotImplementedError` by default.
Overriding this on a subclass can allow common
behavior to be applied to all operations.
For example, overriding :class:`.ColumnOperators`
to apply ``func.lower()`` to the left and right
side::
class MyComparator(ColumnOperators):
def operate(self, op, other):
return op(func.lower(self), func.lower(other))
:param op: Operator callable.
:param \*other: the 'other' side of the operation. Will
be a single scalar for most operations.
:param \**kwargs: modifiers. These may be passed by special
operators such as :meth:`ColumnOperators.contains`.
"""
raise NotImplementedError(str(op))
def reverse_operate(self, op, other, **kwargs):
"""Reverse operate on an argument.
Usage is the same as :meth:`operate`.
"""
raise NotImplementedError(str(op))
class custom_op(object):
"""Represent a 'custom' operator.
:class:`.custom_op` is normally instantitated when the
:meth:`.ColumnOperators.op` method is used to create a
custom operator callable. The class can also be used directly
when programmatically constructing expressions. E.g.
to represent the "factorial" operation::
from sqlalchemy.sql import UnaryExpression
from sqlalchemy.sql import operators
from sqlalchemy import Numeric
unary = UnaryExpression(table.c.somecolumn,
modifier=operators.custom_op("!"),
type_=Numeric)
"""
__name__ = 'custom_op'
def __init__(self, opstring, precedence=0, is_comparison=False):
self.opstring = opstring
self.precedence = precedence
self.is_comparison = is_comparison
def __eq__(self, other):
return isinstance(other, custom_op) and \
other.opstring == self.opstring
def __hash__(self):
return id(self)
def __call__(self, left, right, **kw):
return left.operate(self, right, **kw)
class ColumnOperators(Operators):
"""Defines boolean, comparison, and other operators for
:class:`.ColumnElement` expressions.
By default, all methods call down to
:meth:`.operate` or :meth:`.reverse_operate`,
passing in the appropriate operator function from the
Python builtin ``operator`` module or
a SQLAlchemy-specific operator function from
:mod:`sqlalchemy.expression.operators`. For example
the ``__eq__`` function::
def __eq__(self, other):
return self.operate(operators.eq, other)
Where ``operators.eq`` is essentially::
def eq(a, b):
return a == b
The core column expression unit :class:`.ColumnElement`
overrides :meth:`.Operators.operate` and others
to return further :class:`.ColumnElement` constructs,
so that the ``==`` operation above is replaced by a clause
construct.
See also:
:ref:`types_operators`
:attr:`.TypeEngine.comparator_factory`
:class:`.ColumnOperators`
:class:`.PropComparator`
"""
__slots__ = ()
timetuple = None
"""Hack, allows datetime objects to be compared on the LHS."""
def __lt__(self, other):
"""Implement the ``<`` operator.
In a column context, produces the clause ``a < b``.
"""
return self.operate(lt, other)
def __le__(self, other):
"""Implement the ``<=`` operator.
In a column context, produces the clause ``a <= b``.
"""
return self.operate(le, other)
__hash__ = Operators.__hash__
def __eq__(self, other):
"""Implement the ``==`` operator.
In a column context, produces the clause ``a = b``.
If the target is ``None``, produces ``a IS NULL``.
"""
return self.operate(eq, other)
def __ne__(self, other):
"""Implement the ``!=`` operator.
In a column context, produces the clause ``a != b``.
If the target is ``None``, produces ``a IS NOT NULL``.
"""
return self.operate(ne, other)
def __gt__(self, other):
"""Implement the ``>`` operator.
In a column context, produces the clause ``a > b``.
"""
return self.operate(gt, other)
def __ge__(self, other):
"""Implement the ``>=`` operator.
In a column context, produces the clause ``a >= b``.
"""
return self.operate(ge, other)
def __neg__(self):
"""Implement the ``-`` operator.
In a column context, produces the clause ``-a``.
"""
return self.operate(neg)
def __contains__(self, other):
return self.operate(contains, other)
def __getitem__(self, index):
"""Implement the [] operator.
This can be used by some database-specific types
such as Postgresql ARRAY and HSTORE.
"""
return self.operate(getitem, index)
def __lshift__(self, other):
"""implement the << operator.
Not used by SQLAlchemy core, this is provided
for custom operator systems which want to use
<< as an extension point.
"""
return self.operate(lshift, other)
def __rshift__(self, other):
"""implement the >> operator.
Not used by SQLAlchemy core, this is provided
for custom operator systems which want to use
>> as an extension point.
"""
return self.operate(rshift, other)
def concat(self, other):
"""Implement the 'concat' operator.
In a column context, produces the clause ``a || b``,
or uses the ``concat()`` operator on MySQL.
"""
return self.operate(concat_op, other)
def like(self, other, escape=None):
"""Implement the ``like`` operator.
In a column context, produces the clause ``a LIKE other``.
E.g.::
select([sometable]).where(sometable.c.column.like("%foobar%"))
:param other: expression to be compared
:param escape: optional escape character, renders the ``ESCAPE``
keyword, e.g.::
somecolumn.like("foo/%bar", escape="/")
.. seealso::
:meth:`.ColumnOperators.ilike`
"""
return self.operate(like_op, other, escape=escape)
def ilike(self, other, escape=None):
"""Implement the ``ilike`` operator.
In a column context, produces the clause ``a ILIKE other``.
E.g.::
select([sometable]).where(sometable.c.column.ilike("%foobar%"))
:param other: expression to be compared
:param escape: optional escape character, renders the ``ESCAPE``
keyword, e.g.::
somecolumn.ilike("foo/%bar", escape="/")
.. seealso::
:meth:`.ColumnOperators.like`
"""
return self.operate(ilike_op, other, escape=escape)
def in_(self, other):
"""Implement the ``in`` operator.
In a column context, produces the clause ``a IN other``.
"other" may be a tuple/list of column expressions,
or a :func:`~.expression.select` construct.
"""
return self.operate(in_op, other)
def notin_(self, other):
"""implement the ``NOT IN`` operator.
This is equivalent to using negation with
:meth:`.ColumnOperators.in_`, i.e. ``~x.in_(y)``.
.. versionadded:: 0.8
.. seealso::
:meth:`.ColumnOperators.in_`
"""
return self.operate(notin_op, other)
def notlike(self, other, escape=None):
"""implement the ``NOT LIKE`` operator.
This is equivalent to using negation with
:meth:`.ColumnOperators.like`, i.e. ``~x.like(y)``.
.. versionadded:: 0.8
.. seealso::
:meth:`.ColumnOperators.like`
"""
return self.operate(notlike_op, other, escape=escape)
def notilike(self, other, escape=None):
"""implement the ``NOT ILIKE`` operator.
This is equivalent to using negation with
:meth:`.ColumnOperators.ilike`, i.e. ``~x.ilike(y)``.
.. versionadded:: 0.8
.. seealso::
:meth:`.ColumnOperators.ilike`
"""
return self.operate(notilike_op, other, escape=escape)
def is_(self, other):
"""Implement the ``IS`` operator.
Normally, ``IS`` is generated automatically when comparing to a
value of ``None``, which resolves to ``NULL``. However, explicit
usage of ``IS`` may be desirable if comparing to boolean values
on certain platforms.
.. versionadded:: 0.7.9
.. seealso:: :meth:`.ColumnOperators.isnot`
"""
return self.operate(is_, other)
def isnot(self, other):
"""Implement the ``IS NOT`` operator.
Normally, ``IS NOT`` is generated automatically when comparing to a
value of ``None``, which resolves to ``NULL``. However, explicit
usage of ``IS NOT`` may be desirable if comparing to boolean values
on certain platforms.
.. versionadded:: 0.7.9
.. seealso:: :meth:`.ColumnOperators.is_`
"""
return self.operate(isnot, other)
def startswith(self, other, **kwargs):
"""Implement the ``startwith`` operator.
In a column context, produces the clause ``LIKE '<other>%'``
"""
return self.operate(startswith_op, other, **kwargs)
def endswith(self, other, **kwargs):
"""Implement the 'endswith' operator.
In a column context, produces the clause ``LIKE '%<other>'``
"""
return self.operate(endswith_op, other, **kwargs)
def contains(self, other, **kwargs):
"""Implement the 'contains' operator.
In a column context, produces the clause ``LIKE '%<other>%'``
"""
return self.operate(contains_op, other, **kwargs)
def match(self, other, **kwargs):
"""Implements a database-specific 'match' operator.
:meth:`~.ColumnOperators.match` attempts to resolve to
a MATCH-like function or operator provided by the backend.
Examples include:
* Postgresql - renders ``x @@ to_tsquery(y)``
* MySQL - renders ``MATCH (x) AGAINST (y IN BOOLEAN MODE)``
* Oracle - renders ``CONTAINS(x, y)``
* other backends may provide special implementations.
* Backends without any special implementation will emit
the operator as "MATCH". This is compatible with SQlite, for
example.
"""
return self.operate(match_op, other, **kwargs)
def desc(self):
"""Produce a :func:`~.expression.desc` clause against the
parent object."""
return self.operate(desc_op)
def asc(self):
"""Produce a :func:`~.expression.asc` clause against the
parent object."""
return self.operate(asc_op)
def nullsfirst(self):
"""Produce a :func:`~.expression.nullsfirst` clause against the
parent object."""
return self.operate(nullsfirst_op)
def nullslast(self):
"""Produce a :func:`~.expression.nullslast` clause against the
parent object."""
return self.operate(nullslast_op)
def collate(self, collation):
"""Produce a :func:`~.expression.collate` clause against
the parent object, given the collation string."""
return self.operate(collate, collation)
def __radd__(self, other):
"""Implement the ``+`` operator in reverse.
See :meth:`.ColumnOperators.__add__`.
"""
return self.reverse_operate(add, other)
def __rsub__(self, other):
"""Implement the ``-`` operator in reverse.
See :meth:`.ColumnOperators.__sub__`.
"""
return self.reverse_operate(sub, other)
def __rmul__(self, other):
"""Implement the ``*`` operator in reverse.
See :meth:`.ColumnOperators.__mul__`.
"""
return self.reverse_operate(mul, other)
def __rdiv__(self, other):
"""Implement the ``/`` operator in reverse.
See :meth:`.ColumnOperators.__div__`.
"""
return self.reverse_operate(div, other)
def __rmod__(self, other):
"""Implement the ``%`` operator in reverse.
See :meth:`.ColumnOperators.__mod__`.
"""
return self.reverse_operate(mod, other)
def between(self, cleft, cright, symmetric=False):
"""Produce a :func:`~.expression.between` clause against
the parent object, given the lower and upper range.
"""
return self.operate(between_op, cleft, cright, symmetric=symmetric)
def distinct(self):
"""Produce a :func:`~.expression.distinct` clause against the
parent object.
"""
return self.operate(distinct_op)
def __add__(self, other):
"""Implement the ``+`` operator.
In a column context, produces the clause ``a + b``
if the parent object has non-string affinity.
If the parent object has a string affinity,
produces the concatenation operator, ``a || b`` -
see :meth:`.ColumnOperators.concat`.
"""
return self.operate(add, other)
def __sub__(self, other):
"""Implement the ``-`` operator.
In a column context, produces the clause ``a - b``.
"""
return self.operate(sub, other)
def __mul__(self, other):
"""Implement the ``*`` operator.
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 istrue(a):
raise NotImplementedError()
def isfalse(a):
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, symmetric=False):
return a.between(b, c, symmetric=symmetric)
def notbetween_op(a, b, c, symmetric=False):
return a.notbetween(b, c, symmetric=symmetric)
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, **kw):
return a.match(b, **kw)
def notmatch_op(a, b, **kw):
return a.notmatch(b, **kw)
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, like_op])
def is_comparison(op):
return op in _comparison or \
isinstance(op, custom_op) and op.is_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).
"""
_asbool = util.symbol('_asbool', canonical=-10)
_smallest = util.symbol('_smallest', canonical=-100)
_largest = util.symbol('_largest', canonical=100)
_PRECEDENCE = {
from_: 15,
getitem: 15,
mul: 8,
truediv: 8,
div: 8,
mod: 8,
neg: 8,
add: 7,
sub: 7,
concat_op: 6,
match_op: 6,
notmatch_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,
notbetween_op: 5,
distinct_op: 5,
inv: 5,
istrue: 5,
isfalse: 5,
and_: 3,
or_: 2,
comma_op: -1,
desc_op: 3,
asc_op: 3,
collate: 4,
as_: -1,
exists: 0,
_asbool: -10,
_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)))
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