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//lib64/python2.7/site-packages/sqlalchemy/dialects/postgresql/json.py

# postgresql/json.py
# Copyright (C) 2005-2020 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
from __future__ import absolute_import

from .base import colspecs
from .base import ischema_names
from ... import types as sqltypes
from ... import util
from ...sql import operators

__all__ = ("JSON", "JSONB")

idx_precedence = operators._PRECEDENCE[operators.json_getitem_op]

ASTEXT = operators.custom_op(
    "->>",
    precedence=idx_precedence,
    natural_self_precedent=True,
    eager_grouping=True,
)

JSONPATH_ASTEXT = operators.custom_op(
    "#>>",
    precedence=idx_precedence,
    natural_self_precedent=True,
    eager_grouping=True,
)

HAS_KEY = operators.custom_op(
    "?",
    precedence=idx_precedence,
    natural_self_precedent=True,
    eager_grouping=True,
)

HAS_ALL = operators.custom_op(
    "?&",
    precedence=idx_precedence,
    natural_self_precedent=True,
    eager_grouping=True,
)

HAS_ANY = operators.custom_op(
    "?|",
    precedence=idx_precedence,
    natural_self_precedent=True,
    eager_grouping=True,
)

CONTAINS = operators.custom_op(
    "@>",
    precedence=idx_precedence,
    natural_self_precedent=True,
    eager_grouping=True,
)

CONTAINED_BY = operators.custom_op(
    "<@",
    precedence=idx_precedence,
    natural_self_precedent=True,
    eager_grouping=True,
)

class JSONPathType(sqltypes.JSON.JSONPathType):
    def bind_processor(self, dialect):
        super_proc = self.string_bind_processor(dialect)

def process(value):
            assert isinstance(value, util.collections_abc.Sequence)
            tokens = [util.text_type(elem) for elem in value]
            value = "{%s}" % (", ".join(tokens))
            if super_proc:
                value = super_proc(value)
            return value

return process

def literal_processor(self, dialect):
        super_proc = self.string_literal_processor(dialect)

return process

colspecs[sqltypes.JSON.JSONPathType] = JSONPathType

class JSON(sqltypes.JSON):
    """Represent the PostgreSQL JSON type.

This type is a specialization of the Core-level :class:`.types.JSON`
    type.   Be sure to read the documentation for :class:`.types.JSON` for
    important tips regarding treatment of NULL values and ORM use.

.. versionchanged:: 1.1 :class:`.postgresql.JSON` is now a PostgreSQL-
       specific specialization of the new :class:`.types.JSON` type.

The operators provided by the PostgreSQL version of :class:`.JSON`
    include:

* Index operations (the ``->`` operator)::

data_table.c.data['some key']

data_table.c.data[5]

* Index operations returning text (the ``->>`` operator)::

data_table.c.data['some key'].astext == 'some value'

Note that equivalent functionality is available via the
      :attr:`.JSON.Comparator.as_string` accessor.

* Index operations with CAST
      (equivalent to ``CAST(col ->> ['some key'] AS <type>)``)::

data_table.c.data['some key'].astext.cast(Integer) == 5

Note that equivalent functionality is available via the
      :attr:`.JSON.Comparator.as_integer` and similar accessors.

* Path index operations (the ``#>`` operator)::

data_table.c.data[('key_1', 'key_2', 5, ..., 'key_n')]

* Path index operations returning text (the ``#>>`` operator)::

data_table.c.data[('key_1', 'key_2', 5, ..., 'key_n')].astext == 'some value'

.. versionchanged:: 1.1  The :meth:`.ColumnElement.cast` operator on
       JSON objects now requires that the :attr:`.JSON.Comparator.astext`
       modifier be called explicitly, if the cast works only from a textual
       string.

Index operations return an expression object whose type defaults to
    :class:`.JSON` by default, so that further JSON-oriented instructions
    may be called upon the result type.

Custom serializers and deserializers are specified at the dialect level,
    that is using :func:`.create_engine`.  The reason for this is that when
    using psycopg2, the DBAPI only allows serializers at the per-cursor
    or per-connection level.   E.g.::

engine = create_engine("postgresql://scott:tiger@localhost/test",
                                json_serializer=my_serialize_fn,
                                json_deserializer=my_deserialize_fn
                        )

When using the psycopg2 dialect, the json_deserializer is registered
    against the database using ``psycopg2.extras.register_default_json``.

.. seealso::

:class:`.types.JSON` - Core level JSON type

:class:`.JSONB`

"""  # noqa

astext_type = sqltypes.Text()

def __init__(self, none_as_null=False, astext_type=None):
        """Construct a :class:`.JSON` type.

:param none_as_null: if True, persist the value ``None`` as a
         SQL NULL value, not the JSON encoding of ``null``.   Note that
         when this flag is False, the :func:`.null` construct can still
         be used to persist a NULL value::

from sqlalchemy import null
             conn.execute(table.insert(), data=null())

.. versionchanged:: 0.9.8 - Added ``none_as_null``, and :func:`.null`
            is now supported in order to persist a NULL value.

.. seealso::

:attr:`.JSON.NULL`

:param astext_type: the type to use for the
         :attr:`.JSON.Comparator.astext`
         accessor on indexed attributes.  Defaults to :class:`.types.Text`.

.. versionadded:: 1.1

"""
        super(JSON, self).__init__(none_as_null=none_as_null)
        if astext_type is not None:
            self.astext_type = astext_type

class Comparator(sqltypes.JSON.Comparator):
        """Define comparison operations for :class:`.JSON`."""

@property
        def astext(self):
            """On an indexed expression, use the "astext" (e.g. "->>")
            conversion when rendered in SQL.

E.g.::

select([data_table.c.data['some key'].astext])

.. seealso::

:meth:`.ColumnElement.cast`

"""
            if isinstance(self.expr.right.type, sqltypes.JSON.JSONPathType):
                return self.expr.left.operate(
                    JSONPATH_ASTEXT,
                    self.expr.right,
                    result_type=self.type.astext_type,
                )
            else:
                return self.expr.left.operate(
                    ASTEXT, self.expr.right, result_type=self.type.astext_type
                )

comparator_factory = Comparator

colspecs[sqltypes.JSON] = JSON
ischema_names["json"] = JSON

class JSONB(JSON):
    """Represent the PostgreSQL JSONB type.

The :class:`.JSONB` type stores arbitrary JSONB format data, e.g.::

data_table = Table('data_table', metadata,
            Column('id', Integer, primary_key=True),
            Column('data', JSONB)
        )

with engine.connect() as conn:
            conn.execute(
                data_table.insert(),
                data = {"key1": "value1", "key2": "value2"}
            )

The :class:`.JSONB` type includes all operations provided by
    :class:`.JSON`, including the same behaviors for indexing operations.
    It also adds additional operators specific to JSONB, including
    :meth:`.JSONB.Comparator.has_key`, :meth:`.JSONB.Comparator.has_all`,
    :meth:`.JSONB.Comparator.has_any`, :meth:`.JSONB.Comparator.contains`,
    and :meth:`.JSONB.Comparator.contained_by`.

Like the :class:`.JSON` type, the :class:`.JSONB` type does not detect
    in-place changes when used with the ORM, unless the
    :mod:`sqlalchemy.ext.mutable` extension is used.

Custom serializers and deserializers
    are shared with the :class:`.JSON` class, using the ``json_serializer``
    and ``json_deserializer`` keyword arguments.  These must be specified
    at the dialect level using :func:`.create_engine`.  When using
    psycopg2, the serializers are associated with the jsonb type using
    ``psycopg2.extras.register_default_jsonb`` on a per-connection basis,
    in the same way that ``psycopg2.extras.register_default_json`` is used
    to register these handlers with the json type.

.. versionadded:: 0.9.7

.. seealso::

:class:`.JSON`

"""

__visit_name__ = "JSONB"

class Comparator(JSON.Comparator):
        """Define comparison operations for :class:`.JSON`."""

def has_key(self, other):
            """Boolean expression.  Test for presence of a key.  Note that the
            key may be a SQLA expression.
            """
            return self.operate(HAS_KEY, other, result_type=sqltypes.Boolean)

def has_all(self, other):
            """Boolean expression.  Test for presence of all keys in jsonb
            """
            return self.operate(HAS_ALL, other, result_type=sqltypes.Boolean)

def has_any(self, other):
            """Boolean expression.  Test for presence of any key in jsonb
            """
            return self.operate(HAS_ANY, other, result_type=sqltypes.Boolean)

def contains(self, other, **kwargs):
            """Boolean expression.  Test if keys (or array) are a superset
            of/contained the keys of the argument jsonb expression.
            """
            return self.operate(CONTAINS, other, result_type=sqltypes.Boolean)

def contained_by(self, other):
            """Boolean expression.  Test if keys are a proper subset of the
            keys of the argument jsonb expression.
            """
            return self.operate(
                CONTAINED_BY, other, result_type=sqltypes.Boolean
            )

comparator_factory = Comparator

ischema_names["jsonb"] = JSONB