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https://github.com/psycopg/psycopg2.git
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458 lines
15 KiB
Python
458 lines
15 KiB
Python
"""Implementation of the Range type and adaptation
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"""
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# psycopg/_range.py - Implementation of the Range type and adaptation
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#
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# Copyright (C) 2012 Daniele Varrazzo <daniele.varrazzo@gmail.com>
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#
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# psycopg2 is free software: you can redistribute it and/or modify it
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# under the terms of the GNU Lesser General Public License as published
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# by the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# In addition, as a special exception, the copyright holders give
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# permission to link this program with the OpenSSL library (or with
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# modified versions of OpenSSL that use the same license as OpenSSL),
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# and distribute linked combinations including the two.
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#
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# You must obey the GNU Lesser General Public License in all respects for
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# all of the code used other than OpenSSL.
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#
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# psycopg2 is distributed in the hope that it will be useful, but WITHOUT
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# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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# License for more details.
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import re
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from psycopg2._psycopg import ProgrammingError, InterfaceError
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from psycopg2.extensions import ISQLQuote, adapt, register_adapter
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from psycopg2.extensions import new_type, new_array_type, register_type
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class Range(object):
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"""Python representation for a PostgreSQL range type.
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:param lower: lower bound for the range. None means unbound
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:param upper: upper bound for the range. None means unbound
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:param bounds: one of the literal strings ``()``, ``[)``, ``(]``, ``[]``,
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representing whether the lower or upper bounds are included
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:param empty: if true, the range is empty
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TODO: move this to the docs
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This Python type is only used to pass and retrieve range values to and
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from PostgreSQL and doesn't attempt to replicate the PostgreSQL range
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features: it doesn't perform normalization and doesn't implement all the
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operators supported.
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Although it is possible to instantiate `!Range` objects, the class doesn't
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have an adapter so you cannot normally pass these instances as query
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arguments. To use range objects as query arguments you can either use one
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of the provided subclasses, such as [TODO: the other] `IntRange` or create
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a custom one using `register_range()`.
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"""
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__slots__ = ('_lower', '_upper', '_bounds')
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def __init__(self, lower=None, upper=None, bounds='[)', empty=False):
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if not empty:
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if bounds not in ('[)', '(]', '()', '[]'):
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raise ValueError("bound flags not valid: %r" % bounds)
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self._lower = lower
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self._upper = upper
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self._bounds = bounds
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else:
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self._lower = self._upper = self._bounds = None
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def __repr__(self):
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if self._bounds is None:
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return "%s(empty=True)" % self.__class__.__name__
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else:
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return "%s(%r, %r, %r)" % (self.__class__.__name__,
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self._lower, self._upper, self._bounds)
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@property
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def lower(self):
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"""The lower bound of the range. None if empty or unbound."""
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return self._lower
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@property
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def upper(self):
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"""The upper bound of the range. None if empty or unbound."""
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return self._upper
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@property
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def isempty(self):
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"""True if the range is empty."""
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return self._bounds is None
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@property
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def lower_inf(self):
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"""True if the range doesn't have a lower bound."""
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if self._bounds is None: return False
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return self._lower is None
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@property
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def upper_inf(self):
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"""True if the range doesn't have an upper bound."""
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if self._bounds is None: return False
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return self._upper is None
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@property
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def lower_inc(self):
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"""True if the lower bound is included in the range."""
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if self._bounds is None: return False
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if self._lower is None: return False
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return self._bounds[0] == '['
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@property
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def upper_inc(self):
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"""True if the upper bound is included in the range."""
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if self._bounds is None: return False
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if self._upper is None: return False
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return self._bounds[1] == ']'
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def __contains__(self, x):
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if self._bounds is None: return False
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if self._lower is not None:
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if self._bounds[0] == '[':
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if x < self._lower: return False
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else:
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if x <= self._lower: return False
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if self._upper is not None:
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if self._bounds[1] == ']':
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if x > self._upper: return False
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else:
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if x >= self._upper: return False
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return True
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def __nonzero__(self):
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return self._bounds is not None
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def __eq__(self, other):
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return (self._lower == other._lower
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and self._upper == other._upper
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and self._bounds == other._bounds)
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def __ne__(self, other):
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return not self.__eq__(other)
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def __hash__(self):
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return hash((self._lower, self._upper, self._bounds))
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def __lt__(self, other):
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raise TypeError('Range objects are not ordered')
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__le__ = __gt__ = __ge__ = __lt__
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def register_range(pgrange, pyrange, conn_or_curs, globally=False):
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"""Register a typecaster and an adapter for range a range type.
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:param pgrange: the name of the PostgreSQL range type
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:param pyrange: a Range (strict) subclass, or just the name to give it
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(the class will be available as the `!range` attribute of the returned
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`RangeCaster`.
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:param conn_or_curs: a connection or cursor used to find the oid of the
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range and its subtype; the typecaster is registered in a scope limited
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to this object, unless *globally* is set to `!True`
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:param globally: if `!False` (default) register the typecaster only on
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*conn_or_curs*, otherwise register it globally
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:return: the registered `RangeCaster` instance responsible for the
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conversion
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"""
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caster = RangeCaster._from_db(pgrange, pyrange, conn_or_curs)
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caster._register(not globally and conn_or_curs or None)
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return caster
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class RangeAdapter(object):
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"""`ISQLQuote` adapter for `Range` subclasses.
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This is an abstract class: concrete classes must set a `name` class
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attribute or override `getquoted()`.
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"""
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name = None
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def __init__(self, adapted):
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self.adapted = adapted
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def __conform__(self, proto):
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if self._proto is ISQLQuote:
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return self
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def prepare(self, conn):
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self._conn = conn
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def getquoted(self):
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if self.name is None:
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raise NotImplementedError(
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'RangeAdapter must be subclassed overriding its name '
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'or the getquoted() method')
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r = self.adapted
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if r.isempty:
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return "'empty'::%s" % self.name
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if r.lower is not None:
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a = adapt(r.lower)
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if hasattr(a, 'prepare'):
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a.prepare(self._conn)
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lower = a.getquoted()
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else:
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lower = 'NULL'
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if r.upper is not None:
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a = adapt(r.upper)
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if hasattr(a, 'prepare'):
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a.prepare(self._conn)
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upper = a.getquoted()
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else:
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upper = 'NULL'
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return "%s(%s, %s, '%s')" % (
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self.name, lower, upper, r._bounds)
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class RangeCaster(object):
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"""Helper class to convert between `Range` and PostgreSQL range types."""
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def __init__(self, pgrange, pyrange, oid, subtype_oid, array_oid=None):
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self.subtype_oid = subtype_oid
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self._create_ranges(pgrange, pyrange)
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name = self.adapter.name or self.adapter.__class__.__name__
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self.typecaster = new_type((oid,), name, self.parse)
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if array_oid is not None:
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self.array_typecaster = new_array_type(
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(array_oid,), name + "ARRAY", self.typecaster)
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else:
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self.array_typecaster = None
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def _create_ranges(self, pgrange, pyrange):
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"""Create Range and RangeAdapter classes if needed."""
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# if got a string create a new RangeAdapter concrete type (with a name)
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# else take it as an adapter.
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self.adapter = None
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if isinstance(pgrange, basestring):
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self.adapter = type(pgrange, (RangeAdapter,), {})
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self.adapter.name = pgrange
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else:
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try:
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if issubclass(pgrange, RangeAdapter) and pgrange is not RangeAdapter:
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self.adapter = pgrange
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except TypeError:
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pass
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if self.adapter is None:
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raise TypeError(
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'pgrange must be a string or a RangeAdapter strict subclass')
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self.range = None
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try:
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if isinstance(pyrange, basestring):
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self.range = type(pyrange, (Range,), {})
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if issubclass(pyrange, Range) and pyrange is not Range:
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self.range = pyrange
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except TypeError:
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pass
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if self.range is None:
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raise TypeError(
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'pyrange must be a type or a Range strict subclass')
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@classmethod
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def _from_db(self, name, pyrange, conn_or_curs):
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"""Return a `RangeCaster` instance for the type *pgrange*.
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Raise `ProgrammingError` if the type is not found.
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"""
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from psycopg2.extensions import STATUS_IN_TRANSACTION
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from psycopg2.extras import _solve_conn_curs
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conn, curs = _solve_conn_curs(conn_or_curs)
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if conn.server_version < 90200:
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raise ProgrammingError("range types not available in version %s"
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% conn.server_version)
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# Store the transaction status of the connection to revert it after use
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conn_status = conn.status
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# Use the correct schema
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if '.' in name:
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schema, tname = name.split('.', 1)
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else:
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tname = name
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schema = 'public'
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# get the type oid and attributes
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try:
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curs.execute("""\
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select rngtypid, rngsubtype,
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(select typarray from pg_type where oid = rngtypid)
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from pg_range r
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join pg_type t on t.oid = rngtypid
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join pg_namespace ns on ns.oid = typnamespace
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where typname = %s and ns.nspname = %s;
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""", (tname, schema))
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except ProgrammingError:
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if not conn.autocommit:
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conn.rollback()
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raise
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else:
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rec = curs.fetchone()
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# revert the status of the connection as before the command
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if (conn_status != STATUS_IN_TRANSACTION
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and not conn.autocommit):
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conn.rollback()
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if not rec:
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raise ProgrammingError(
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"PostgreSQL type '%s' not found" % name)
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type, subtype, array = rec
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return RangeCaster(name, pyrange,
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oid=type, subtype_oid=subtype, array_oid=array)
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_re_range = re.compile(r"""
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( \(|\[ ) # lower bound flag
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(?: # lower bound:
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" ( (?: [^"] | "")* ) " # - a quoted string
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| ( [^",]+ ) # - or an unquoted string
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)? # - or empty (not catched)
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,
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(?: # upper bound:
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" ( (?: [^"] | "")* ) " # - a quoted string
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| ( [^"\)\]]+ ) # - or an unquoted string
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)? # - or empty (not catched)
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( \)|\] ) # upper bound flag
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""", re.VERBOSE)
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_re_undouble = re.compile(r'(["\\])\1')
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def parse(self, s, cur=None):
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if s is None:
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return None
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if s == 'empty':
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return self.range(empty=True)
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m = self._re_range.match(s)
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if m is None:
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raise InterfaceError("failed to parse range: %s")
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lower = m.group(3)
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if lower is None:
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lower = m.group(2)
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if lower is not None:
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lower = self._re_undouble.sub(r"\1", lower)
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upper = m.group(5)
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if upper is None:
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upper = m.group(4)
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if upper is not None:
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upper = self._re_undouble.sub(r"\1", upper)
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if cur is not None:
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lower = cur.cast(self.subtype_oid, lower)
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upper = cur.cast(self.subtype_oid, upper)
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bounds = m.group(1) + m.group(6)
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return self.range(lower, upper, bounds)
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def _register(self, scope=None):
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register_type(self.typecaster, scope)
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if self.array_typecaster is not None:
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register_type(self.array_typecaster, scope)
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register_adapter(self.range, self.adapter)
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class NumericRange(Range):
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"""A `Range` suitable to pass Python numeric types to a PostgreSQL range."""
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pass
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class DateRange(Range):
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"""Represents :sql:`daterange` values."""
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pass
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class DateTimeRange(Range):
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"""Represents :sql:`tsrange` values."""
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pass
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class DateTimeTZRange(Range):
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"""Represents :sql:`tstzrange` values."""
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pass
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# Special adaptation for NumericRange. Allows to pass number range regardless
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# of whether they are ints, floats and what size of ints are, which are
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# pointless in Python world. On the way back, no numeric range is casted to
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# NumericRange, but only to their subclasses
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class NumberRangeAdapter(RangeAdapter):
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"""Adapt a range if the subtype doesn't need quotes."""
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def getquoted(self):
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r = self.adapted
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if r.isempty:
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return "'empty'"
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if not r.lower_inf:
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# not exactly: we are relying that none of these object is really
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# quoted (they are numbers). Also, I'm lazy and not preparing the
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# adapter because I assume encoding doesn't matter for these
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# objects.
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lower = adapt(r.lower).getquoted()
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else:
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lower = ''
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if not r.upper_inf:
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upper = adapt(r.upper).getquoted()
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else:
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upper = ''
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return "'%s%s,%s%s'" % (
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r._bounds[0], lower, upper, r._bounds[1])
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# TODO: probably won't work with infs, nans and other tricky cases.
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register_adapter(NumericRange, NumberRangeAdapter)
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# Register globally typecasters and adapters for builtin range types.
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# note: the adapter is registered more than once, but this is harmless.
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int4range_caster = RangeCaster(NumberRangeAdapter, NumericRange,
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oid=3904, subtype_oid=23, array_oid=3905)
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int4range_caster._register()
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int8range_caster = RangeCaster(NumberRangeAdapter, NumericRange,
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oid=3926, subtype_oid=20, array_oid=3927)
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int8range_caster._register()
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numrange_caster = RangeCaster(NumberRangeAdapter, NumericRange,
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oid=3906, subtype_oid=1700, array_oid=3907)
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numrange_caster._register()
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daterange_caster = RangeCaster('daterange', DateRange,
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oid=3912, subtype_oid=1082, array_oid=3913)
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daterange_caster._register()
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tsrange_caster = RangeCaster('tsrange', DateTimeRange,
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oid=3908, subtype_oid=1114, array_oid=3909)
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tsrange_caster._register()
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tstzrange_caster = RangeCaster('tstzrange', DateTimeTZRange,
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oid=3910, subtype_oid=1184, array_oid=3911)
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tstzrange_caster._register()
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