# sql/operators.py
# Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: https://www.opensource.org/licenses/mit-license.php

# This module is part of SQLAlchemy and is released under
# the MIT License: https://www.opensource.org/licenses/mit-license.php

"""Defines operators used in SQL expressions."""

from operator import add
from operator import and_
from operator import contains
from operator import eq
from operator import ge
from operator import getitem
from operator import gt
from operator import inv
from operator import le
from operator import lshift
from operator import lt
from operator import mod
from operator import mul
from operator import ne
from operator import neg
from operator import or_
from operator import rshift
from operator import sub
from operator import truediv

from .. import util


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, return_type=None
    ):
        """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.

        :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.

        :param return_type: a :class:`.TypeEngine` class or object that will
          force the return type of an expression produced by this operator
          to be of that type.   By default, operators that specify
          :paramref:`.Operators.op.is_comparison` will resolve to
          :class:`.Boolean`, and those that do not will be of the same
          type as the left-hand operand.

        .. seealso::

            :ref:`types_operators`

            :ref:`relationship_custom_operator`

        """
        operator = custom_op(opstring, precedence, is_comparison, return_type)

        def against(other):
            return operator(self, other)

        return against

    def bool_op(self, opstring, precedence=0):
        """Return a custom boolean operator.

        This method is shorthand for calling
        :meth:`.Operators.op` and passing the
        :paramref:`.Operators.op.is_comparison`
        flag with True.

        .. seealso::

            :meth:`.Operators.op`

        """
        return self.op(opstring, precedence=precedence, is_comparison=True)

    def operate(self, op, *other, **kwargs):
        r"""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 instantiated when the
    :meth:`.Operators.op` or :meth:`.Operators.bool_op` methods
    are 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)


    .. seealso::

        :meth:`.Operators.op`

        :meth:`.Operators.bool_op`

    """

    __name__ = "custom_op"

    def __init__(
        self,
        opstring,
        precedence=0,
        is_comparison=False,
        return_type=None,
        natural_self_precedent=False,
        eager_grouping=False,
    ):
        self.opstring = opstring
        self.precedence = precedence
        self.is_comparison = is_comparison
        self.natural_self_precedent = natural_self_precedent
        self.eager_grouping = eager_grouping
        self.return_type = (
            return_type._to_instance(return_type) if return_type else None
        )

    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:`_expression.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:`_expression.ColumnElement`
    overrides :meth:`.Operators.operate` and others
    to return further :class:`_expression.ColumnElement` constructs,
    so that the ``==`` operation above is replaced by a clause
    construct.

    .. seealso::

        :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 is_distinct_from(self, other):
        """Implement the ``IS DISTINCT FROM`` operator.

        Renders "a IS DISTINCT FROM b" on most platforms;
        on some such as SQLite may render "a IS NOT b".

        .. versionadded:: 1.1

        """
        return self.operate(is_distinct_from, other)

    def is_not_distinct_from(self, other):
        """Implement the ``IS NOT DISTINCT FROM`` operator.

        Renders "a IS NOT DISTINCT FROM b" on most platforms;
        on some such as SQLite may render "a IS b".

        .. versionchanged:: 1.4 The ``is_not_distinct_from()`` operator is
           renamed from ``isnot_distinct_from()`` in previous releases.
           The previous name remains available for backwards compatibility.

        .. versionadded:: 1.1

        """
        return self.operate(is_not_distinct_from, other)

    # deprecated 1.4; see #5435
    isnot_distinct_from = is_not_distinct_from

    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):
        r"""Implement the ``like`` operator.

        In a column context, produces the expression::

            a LIKE other

        E.g.::

            stmt = 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):
        r"""Implement the ``ilike`` operator, e.g. case insensitive LIKE.

        In a column context, produces an expression either of the form::

            lower(a) LIKE lower(other)

        Or on backends that support the ILIKE operator::

            a ILIKE other

        E.g.::

            stmt = 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 ``column IN <other>``.

        The given parameter ``other`` may be:

        * A list of literal values, e.g.::

            stmt.where(column.in_([1, 2, 3]))

          In this calling form, the list of items is converted to a set of
          bound parameters the same length as the list given::

            WHERE COL IN (?, ?, ?)

        * A list of tuples may be provided if the comparison is against a
          :func:`.tuple_` containing multiple expressions::

            from sqlalchemy import tuple_
            stmt.where(tuple_(col1, col2).in_([(1, 10), (2, 20), (3, 30)]))

        * An empty list, e.g.::

            stmt.where(column.in_([]))

          In this calling form, the expression renders an "empty set"
          expression.  These expressions are tailored to individual backends
          and are generally trying to get an empty SELECT statement as a
          subquery.  Such as on SQLite, the expression is::

            WHERE col IN (SELECT 1 FROM (SELECT 1) WHERE 1!=1)

          .. versionchanged:: 1.4  empty IN expressions now use an
             execution-time generated SELECT subquery in all cases.

        * A bound parameter, e.g. :func:`.bindparam`, may be used if it
          includes the :paramref:`.bindparam.expanding` flag::

            stmt.where(column.in_(bindparam('value', expanding=True)))

          In this calling form, the expression renders a special non-SQL
          placeholder expression that looks like::

            WHERE COL IN ([EXPANDING_value])

          This placeholder expression is intercepted at statement execution
          time to be converted into the variable number of bound parameter
          form illustrated earlier.   If the statement were executed as::

            connection.execute(stmt, {"value": [1, 2, 3]})

          The database would be passed a bound parameter for each value::

            WHERE COL IN (?, ?, ?)

          .. versionadded:: 1.2 added "expanding" bound parameters

          If an empty list is passed, a special "empty list" expression,
          which is specific to the database in use, is rendered.  On
          SQLite this would be::

            WHERE COL IN (SELECT 1 FROM (SELECT 1) WHERE 1!=1)

          .. versionadded:: 1.3 "expanding" bound parameters now support
             empty lists

        * a :func:`_expression.select` construct, which is usually a
          correlated scalar select::

            stmt.where(
                column.in_(
                    select(othertable.c.y).
                    where(table.c.x == othertable.c.x)
                )
            )

          In this calling form, :meth:`.ColumnOperators.in_` renders as given::

            WHERE COL IN (SELECT othertable.y
            FROM othertable WHERE othertable.x = table.x)

        :param other: a list of literals, a :func:`_expression.select`
         construct, or a :func:`.bindparam` construct that includes the
         :paramref:`.bindparam.expanding` flag set to True.

        """
        return self.operate(in_op, other)

    def not_in(self, other):
        """implement the ``NOT IN`` operator.

        This is equivalent to using negation with
        :meth:`.ColumnOperators.in_`, i.e. ``~x.in_(y)``.

        In the case that ``other`` is an empty sequence, the compiler
        produces an "empty not in" expression.   This defaults to the
        expression "1 = 1" to produce true in all cases.  The
        :paramref:`_sa.create_engine.empty_in_strategy` may be used to
        alter this behavior.

        .. versionchanged:: 1.4 The ``not_in()`` operator is renamed from
           ``notin_()`` in previous releases.  The previous name remains
           available for backwards compatibility.

        .. versionchanged:: 1.2  The :meth:`.ColumnOperators.in_` and
           :meth:`.ColumnOperators.not_in` operators
           now produce a "static" expression for an empty IN sequence
           by default.

        .. seealso::

            :meth:`.ColumnOperators.in_`

        """
        return self.operate(not_in_op, other)

    # deprecated 1.4; see #5429
    notin_ = not_in

    def not_like(self, other, escape=None):
        """implement the ``NOT LIKE`` operator.

        This is equivalent to using negation with
        :meth:`.ColumnOperators.like`, i.e. ``~x.like(y)``.

        .. versionchanged:: 1.4 The ``not_like()`` operator is renamed from
           ``notlike()`` in previous releases.  The previous name remains
           available for backwards compatibility.

        .. seealso::

            :meth:`.ColumnOperators.like`

        """
        return self.operate(notlike_op, other, escape=escape)

    # deprecated 1.4; see #5435
    notlike = not_like

    def not_ilike(self, other, escape=None):
        """implement the ``NOT ILIKE`` operator.

        This is equivalent to using negation with
        :meth:`.ColumnOperators.ilike`, i.e. ``~x.ilike(y)``.

        .. versionchanged:: 1.4 The ``not_ilike()`` operator is renamed from
           ``notilike()`` in previous releases.  The previous name remains
           available for backwards compatibility.

        .. seealso::

            :meth:`.ColumnOperators.ilike`

        """
        return self.operate(notilike_op, other, escape=escape)

    # deprecated 1.4; see #5435
    notilike = not_ilike

    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.

        .. seealso:: :meth:`.ColumnOperators.is_not`

        """
        return self.operate(is_, other)

    def is_not(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.

        .. versionchanged:: 1.4 The ``is_not()`` operator is renamed from
           ``isnot()`` in previous releases.  The previous name remains
           available for backwards compatibility.

        .. seealso:: :meth:`.ColumnOperators.is_`

        """
        return self.operate(is_not, other)

    # deprecated 1.4; see #5429
    isnot = is_not

    def startswith(self, other, **kwargs):
        r"""Implement the ``startswith`` operator.

        Produces a LIKE expression that tests against a match for the start
        of a string value::

            column LIKE <other> || '%'

        E.g.::

            stmt = select(sometable).\
                where(sometable.c.column.startswith("foobar"))

        Since the operator uses ``LIKE``, wildcard characters
        ``"%"`` and ``"_"`` that are present inside the <other> expression
        will behave like wildcards as well.   For literal string
        values, the :paramref:`.ColumnOperators.startswith.autoescape` flag
        may be set to ``True`` to apply escaping to occurrences of these
        characters within the string value so that they match as themselves
        and not as wildcard characters.  Alternatively, the
        :paramref:`.ColumnOperators.startswith.escape` parameter will establish
        a given character as an escape character which can be of use when
        the target expression is not a literal string.

        :param other: expression to be compared.   This is usually a plain
          string value, but can also be an arbitrary SQL expression.  LIKE
          wildcard characters ``%`` and ``_`` are not escaped by default unless
          the :paramref:`.ColumnOperators.startswith.autoescape` flag is
          set to True.

        :param autoescape: boolean; when True, establishes an escape character
          within the LIKE expression, then applies it to all occurrences of
          ``"%"``, ``"_"`` and the escape character itself within the
          comparison value, which is assumed to be a literal string and not a
          SQL expression.

          An expression such as::

            somecolumn.startswith("foo%bar", autoescape=True)

          Will render as::

            somecolumn LIKE :param || '%' ESCAPE '/'

          With the value of ``:param`` as ``"foo/%bar"``.

        :param escape: a character which when given will render with the
          ``ESCAPE`` keyword to establish that character as the escape
          character.  This character can then be placed preceding occurrences
          of ``%`` and ``_`` to allow them to act as themselves and not
          wildcard characters.

          An expression such as::

            somecolumn.startswith("foo/%bar", escape="^")

          Will render as::

            somecolumn LIKE :param || '%' ESCAPE '^'

          The parameter may also be combined with
          :paramref:`.ColumnOperators.startswith.autoescape`::

            somecolumn.startswith("foo%bar^bat", escape="^", autoescape=True)

          Where above, the given literal parameter will be converted to
          ``"foo^%bar^^bat"`` before being passed to the database.

        .. seealso::

            :meth:`.ColumnOperators.endswith`

            :meth:`.ColumnOperators.contains`

            :meth:`.ColumnOperators.like`

        """
        return self.operate(startswith_op, other, **kwargs)

    def endswith(self, other, **kwargs):
        r"""Implement the 'endswith' operator.

        Produces a LIKE expression that tests against a match for the end
        of a string value::

            column LIKE '%' || <other>

        E.g.::

            stmt = select(sometable).\
                where(sometable.c.column.endswith("foobar"))

        Since the operator uses ``LIKE``, wildcard characters
        ``"%"`` and ``"_"`` that are present inside the <other> expression
        will behave like wildcards as well.   For literal string
        values, the :paramref:`.ColumnOperators.endswith.autoescape` flag
        may be set to ``True`` to apply escaping to occurrences of these
        characters within the string value so that they match as themselves
        and not as wildcard characters.  Alternatively, the
        :paramref:`.ColumnOperators.endswith.escape` parameter will establish
        a given character as an escape character which can be of use when
        the target expression is not a literal string.

        :param other: expression to be compared.   This is usually a plain
          string value, but can also be an arbitrary SQL expression.  LIKE
          wildcard characters ``%`` and ``_`` are not escaped by default unless
          the :paramref:`.ColumnOperators.endswith.autoescape` flag is
          set to True.

        :param autoescape: boolean; when True, establishes an escape character
          within the LIKE expression, then applies it to all occurrences of
          ``"%"``, ``"_"`` and the escape character itself within the
          comparison value, which is assumed to be a literal string and not a
          SQL expression.

          An expression such as::

            somecolumn.endswith("foo%bar", autoescape=True)

          Will render as::

            somecolumn LIKE '%' || :param ESCAPE '/'

          With the value of ``:param`` as ``"foo/%bar"``.

        :param escape: a character which when given will render with the
          ``ESCAPE`` keyword to establish that character as the escape
          character.  This character can then be placed preceding occurrences
          of ``%`` and ``_`` to allow them to act as themselves and not
          wildcard characters.

          An expression such as::

            somecolumn.endswith("foo/%bar", escape="^")

          Will render as::

            somecolumn LIKE '%' || :param ESCAPE '^'

          The parameter may also be combined with
          :paramref:`.ColumnOperators.endswith.autoescape`::

            somecolumn.endswith("foo%bar^bat", escape="^", autoescape=True)

          Where above, the given literal parameter will be converted to
          ``"foo^%bar^^bat"`` before being passed to the database.

        .. seealso::

            :meth:`.ColumnOperators.startswith`

            :meth:`.ColumnOperators.contains`

            :meth:`.ColumnOperators.like`

        """
        return self.operate(endswith_op, other, **kwargs)

    def contains(self, other, **kwargs):
        r"""Implement the 'contains' operator.

        Produces a LIKE expression that tests against a match for the middle
        of a string value::

            column LIKE '%' || <other> || '%'

        E.g.::

            stmt = select(sometable).\
                where(sometable.c.column.contains("foobar"))

        Since the operator uses ``LIKE``, wildcard characters
        ``"%"`` and ``"_"`` that are present inside the <other> expression
        will behave like wildcards as well.   For literal string
        values, the :paramref:`.ColumnOperators.contains.autoescape` flag
        may be set to ``True`` to apply escaping to occurrences of these
        characters within the string value so that they match as themselves
        and not as wildcard characters.  Alternatively, the
        :paramref:`.ColumnOperators.contains.escape` parameter will establish
        a given character as an escape character which can be of use when
        the target expression is not a literal string.

        :param other: expression to be compared.   This is usually a plain
          string value, but can also be an arbitrary SQL expression.  LIKE
          wildcard characters ``%`` and ``_`` are not escaped by default unless
          the :paramref:`.ColumnOperators.contains.autoescape` flag is
          set to True.

        :param autoescape: boolean; when True, establishes an escape character
          within the LIKE expression, then applies it to all occurrences of
          ``"%"``, ``"_"`` and the escape character itself within the
          comparison value, which is assumed to be a literal string and not a
          SQL expression.

          An expression such as::

            somecolumn.contains("foo%bar", autoescape=True)

          Will render as::

            somecolumn LIKE '%' || :param || '%' ESCAPE '/'

          With the value of ``:param`` as ``"foo/%bar"``.

        :param escape: a character which when given will render with the
          ``ESCAPE`` keyword to establish that character as the escape
          character.  This character can then be placed preceding occurrences
          of ``%`` and ``_`` to allow them to act as themselves and not
          wildcard characters.

          An expression such as::

            somecolumn.contains("foo/%bar", escape="^")

          Will render as::

            somecolumn LIKE '%' || :param || '%' ESCAPE '^'

          The parameter may also be combined with
          :paramref:`.ColumnOperators.contains.autoescape`::

            somecolumn.contains("foo%bar^bat", escape="^", autoescape=True)

          Where above, the given literal parameter will be converted to
          ``"foo^%bar^^bat"`` before being passed to the database.

        .. seealso::

            :meth:`.ColumnOperators.startswith`

            :meth:`.ColumnOperators.endswith`

            :meth:`.ColumnOperators.like`


        """
        return self.operate(contains_op, other, **kwargs)

    def match(self, other, **kwargs):
        """Implements a database-specific 'match' operator.

        :meth:`_sql.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)``

          .. seealso::

                :class:`_mysql.match` - MySQL specific construct with
                additional features.

        * 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 regexp_match(self, pattern, flags=None):
        """Implements a database-specific 'regexp match' operator.

        E.g.::

            stmt = select(table.c.some_column).where(
                table.c.some_column.regexp_match('^(b|c)')
            )

        :meth:`_sql.ColumnOperators.regexp_match` attempts to resolve to
        a REGEXP-like function or operator provided by the backend, however
        the specific regular expression syntax and flags available are
        **not backend agnostic**.

        Examples include:

        * PostgreSQL - renders ``x ~ y`` or ``x !~ y`` when negated.
        * Oracle - renders ``REGEXP_LIKE(x, y)``
        * SQLite - uses SQLite's ``REGEXP`` placeholder operator and calls into
          the Python ``re.match()`` builtin.
        * other backends may provide special implementations.
        * Backends without any special implementation will emit
          the operator as "REGEXP" or "NOT REGEXP".  This is compatible with
          SQLite and MySQL, for example.

        Regular expression support is currently implemented for Oracle,
        PostgreSQL, MySQL and MariaDB.  Partial support is available for
        SQLite.  Support among third-party dialects may vary.

        :param pattern: The regular expression pattern string or column
          clause.
        :param flags: Any regular expression string flags to apply. Flags
          tend to be backend specific. It can be a string or a column clause.
          Some backends, like PostgreSQL and MariaDB, may alternatively
          specify the flags as part of the pattern.
          When using the ignore case flag 'i' in PostgreSQL, the ignore case
          regexp match operator ``~*`` or ``!~*`` will be used.

        .. versionadded:: 1.4

        .. seealso::

            :meth:`_sql.ColumnOperators.regexp_replace`


        """
        return self.operate(regexp_match_op, pattern, flags=flags)

    def regexp_replace(self, pattern, replacement, flags=None):
        """Implements a database-specific 'regexp replace' operator.

        E.g.::

            stmt = select(
                table.c.some_column.regexp_replace(
                    'b(..)',
                    'X\1Y',
                    flags='g'
                )
            )

        :meth:`_sql.ColumnOperators.regexp_replace` attempts to resolve to
        a REGEXP_REPLACE-like function provided by the backend, that
        usually emit the function ``REGEXP_REPLACE()``.  However,
        the specific regular expression syntax and flags available are
        **not backend agnostic**.

        Regular expression replacement support is currently implemented for
        Oracle, PostgreSQL, MySQL 8 or greater and MariaDB.  Support among
        third-party dialects may vary.

        :param pattern: The regular expression pattern string or column
          clause.
        :param pattern: The replacement string or column clause.
        :param flags: Any regular expression string flags to apply. Flags
          tend to be backend specific. It can be a string or a column clause.
          Some backends, like PostgreSQL and MariaDB, may alternatively
          specify the flags as part of the pattern.

        .. versionadded:: 1.4

        .. seealso::

            :meth:`_sql.ColumnOperators.regexp_match`

        """
        return self.operate(
            regexp_replace_op, pattern, replacement=replacement, flags=flags
        )

    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 nulls_first(self):
        """Produce a :func:`_expression.nulls_first` clause against the
        parent object.

        .. versionchanged:: 1.4 The ``nulls_first()`` operator is
           renamed from ``nullsfirst()`` in previous releases.
           The previous name remains available for backwards compatibility.
        """
        return self.operate(nulls_first_op)

    # deprecated 1.4; see #5435
    nullsfirst = nulls_first

    def nulls_last(self):
        """Produce a :func:`_expression.nulls_last` clause against the
        parent object.

        .. versionchanged:: 1.4 The ``nulls_last()`` operator is
           renamed from ``nullslast()`` in previous releases.
           The previous name remains available for backwards compatibility.
        """
        return self.operate(nulls_last_op)

    # deprecated 1.4; see #5429
    nullslast = nulls_last

    def collate(self, collation):
        """Produce a :func:`_expression.collate` clause against
        the parent object, given the collation string.

        .. seealso::

            :func:`_expression.collate`

        """
        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 any_(self):
        """Produce an :func:`_expression.any_` clause against the
        parent object.

        See the documentation for :func:`_sql.any_` for examples.

        .. note:: be sure to not confuse the newer
            :meth:`_sql.ColumnOperators.any_` method with its older
            :class:`_types.ARRAY`-specific counterpart, the
            :meth:`_types.ARRAY.Comparator.any` method, which a different
            calling syntax and usage pattern.

        .. versionadded:: 1.1

        """
        return self.operate(any_op)

    def all_(self):
        """Produce an :func:`_expression.all_` clause against the
        parent object.

        See the documentation for :func:`_sql.all_` for examples.

        .. note:: be sure to not confuse the newer
            :meth:`_sql.ColumnOperators.all_` method with its older
            :class:`_types.ARRAY`-specific counterpart, the
            :meth:`_types.ARRAY.Comparator.all` method, which a different
            calling syntax and usage pattern.


        .. versionadded:: 1.1

        """
        return self.operate(all_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)


_commutative = {eq, ne, add, mul}
_comparison = {eq, ne, lt, gt, ge, le}


def commutative_op(fn):
    _commutative.add(fn)
    return fn


def comparison_op(fn):
    _comparison.add(fn)
    return fn


def from_():
    raise NotImplementedError()


@comparison_op
def function_as_comparison_op():
    raise NotImplementedError()


def as_():
    raise NotImplementedError()


def exists():
    raise NotImplementedError()


def is_true(a):
    raise NotImplementedError()


# 1.4 deprecated; see #5435
istrue = is_true


def is_false(a):
    raise NotImplementedError()


# 1.4 deprecated; see #5435
isfalse = is_false


@comparison_op
def is_distinct_from(a, b):
    return a.is_distinct_from(b)


@comparison_op
def is_not_distinct_from(a, b):
    return a.is_not_distinct_from(b)


# deprecated 1.4; see #5435
isnot_distinct_from = is_not_distinct_from


@comparison_op
def is_(a, b):
    return a.is_(b)


@comparison_op
def is_not(a, b):
    return a.is_not(b)


# 1.4 deprecated; see #5429
isnot = is_not


def collate(a, b):
    return a.collate(b)


def op(a, opstring, b):
    return a.op(opstring)(b)


@comparison_op
def like_op(a, b, escape=None):
    return a.like(b, escape=escape)


@comparison_op
def not_like_op(a, b, escape=None):
    return a.notlike(b, escape=escape)


# 1.4 deprecated; see #5435
notlike_op = not_like_op


@comparison_op
def ilike_op(a, b, escape=None):
    return a.ilike(b, escape=escape)


@comparison_op
def not_ilike_op(a, b, escape=None):
    return a.not_ilike(b, escape=escape)


# 1.4 deprecated; see #5435
notilike_op = not_ilike_op


@comparison_op
def between_op(a, b, c, symmetric=False):
    return a.between(b, c, symmetric=symmetric)


@comparison_op
def not_between_op(a, b, c, symmetric=False):
    return ~a.between(b, c, symmetric=symmetric)


# 1.4 deprecated; see #5435
notbetween_op = not_between_op


@comparison_op
def in_op(a, b):
    return a.in_(b)


@comparison_op
def not_in_op(a, b):
    return a.not_in(b)


# 1.4 deprecated; see #5429
notin_op = not_in_op


def distinct_op(a):
    return a.distinct()


def any_op(a):
    return a.any_()


def all_op(a):
    return a.all_()


def _escaped_like_impl(fn, other, escape, autoescape):
    if autoescape:
        if autoescape is not True:
            util.warn(
                "The autoescape parameter is now a simple boolean True/False"
            )
        if escape is None:
            escape = "/"

        if not isinstance(other, util.compat.string_types):
            raise TypeError("String value expected when autoescape=True")

        if escape not in ("%", "_"):
            other = other.replace(escape, escape + escape)

        other = other.replace("%", escape + "%").replace("_", escape + "_")

    return fn(other, escape=escape)


@comparison_op
def startswith_op(a, b, escape=None, autoescape=False):
    return _escaped_like_impl(a.startswith, b, escape, autoescape)


@comparison_op
def not_startswith_op(a, b, escape=None, autoescape=False):
    return ~_escaped_like_impl(a.startswith, b, escape, autoescape)


# 1.4 deprecated; see #5435
notstartswith_op = not_startswith_op


@comparison_op
def endswith_op(a, b, escape=None, autoescape=False):
    return _escaped_like_impl(a.endswith, b, escape, autoescape)


@comparison_op
def not_endswith_op(a, b, escape=None, autoescape=False):
    return ~_escaped_like_impl(a.endswith, b, escape, autoescape)


# 1.4 deprecated; see #5435
notendswith_op = not_endswith_op


@comparison_op
def contains_op(a, b, escape=None, autoescape=False):
    return _escaped_like_impl(a.contains, b, escape, autoescape)


@comparison_op
def not_contains_op(a, b, escape=None, autoescape=False):
    return ~_escaped_like_impl(a.contains, b, escape, autoescape)


# 1.4 deprecated; see #5435
notcontains_op = not_contains_op


@comparison_op
def match_op(a, b, **kw):
    return a.match(b, **kw)


@comparison_op
def regexp_match_op(a, b, flags=None):
    return a.regexp_match(b, flags=flags)


@comparison_op
def not_regexp_match_op(a, b, flags=None):
    return ~a.regexp_match(b, flags=flags)


def regexp_replace_op(a, b, replacement, flags=None):
    return a.regexp_replace(b, replacement=replacement, flags=flags)


@comparison_op
def not_match_op(a, b, **kw):
    return ~a.match(b, **kw)


# 1.4 deprecated; see #5429
notmatch_op = not_match_op


def comma_op(a, b):
    raise NotImplementedError()


def filter_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 nulls_first_op(a):
    return a.nulls_first()


# 1.4 deprecated; see #5435
nullsfirst_op = nulls_first_op


def nulls_last_op(a):
    return a.nulls_last()


# 1.4 deprecated; see #5435
nullslast_op = nulls_last_op


def json_getitem_op(a, b):
    raise NotImplementedError()


def json_path_getitem_op(a, b):
    raise NotImplementedError()


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, nulls_first_op, nulls_last_op)


def is_natural_self_precedent(op):
    return (
        op in _natural_self_precedent
        or isinstance(op, custom_op)
        and op.natural_self_precedent
    )


_booleans = (inv, is_true, is_false, and_, or_)


def is_boolean(op):
    return is_comparison(op) or op in _booleans


_mirror = {gt: lt, ge: le, lt: gt, le: ge}


def mirror(op):
    """rotate a comparison operator 180 degrees.

    Note this is not the same as negation.

    """
    return _mirror.get(op, op)


_associative = _commutative.union([concat_op, and_, or_]).difference([eq, ne])


def is_associative(op):
    return op in _associative


_natural_self_precedent = _associative.union(
    [getitem, json_getitem_op, json_path_getitem_op]
)
"""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,
    function_as_comparison_op: 15,
    any_op: 15,
    all_op: 15,
    getitem: 15,
    json_getitem_op: 15,
    json_path_getitem_op: 15,
    mul: 8,
    truediv: 8,
    div: 8,
    mod: 8,
    neg: 8,
    add: 7,
    sub: 7,
    concat_op: 6,
    filter_op: 6,
    match_op: 5,
    not_match_op: 5,
    regexp_match_op: 5,
    not_regexp_match_op: 5,
    regexp_replace_op: 5,
    ilike_op: 5,
    not_ilike_op: 5,
    like_op: 5,
    not_like_op: 5,
    in_op: 5,
    not_in_op: 5,
    is_: 5,
    is_not: 5,
    eq: 5,
    ne: 5,
    is_distinct_from: 5,
    is_not_distinct_from: 5,
    gt: 5,
    lt: 5,
    ge: 5,
    le: 5,
    between_op: 5,
    not_between_op: 5,
    distinct_op: 5,
    inv: 5,
    is_true: 5,
    is_false: 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 is_natural_self_precedent(operator):
        return False
    else:
        return _PRECEDENCE.get(
            operator, getattr(operator, "precedence", _smallest)
        ) <= _PRECEDENCE.get(against, getattr(against, "precedence", _largest))
