300 lines
8.7 KiB
Python
300 lines
8.7 KiB
Python
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#!/bin/env python
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#------------------------------------------------------------------------
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# Copyright (c) 1997-2001 by Total Control Software
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# All Rights Reserved
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#------------------------------------------------------------------------
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#
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# Module Name: dbShelve.py
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#
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# Description: A reimplementation of the standard shelve.py that
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# forces the use of cPickle, and DB.
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#
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# Creation Date: 11/3/97 3:39:04PM
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#
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# License: This is free software. You may use this software for any
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# purpose including modification/redistribution, so long as
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# this header remains intact and that you do not claim any
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# rights of ownership or authorship of this software. This
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# software has been tested, but no warranty is expressed or
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# implied.
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#
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# 13-Dec-2000: Updated to be used with the new bsddb3 package.
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# Added DBShelfCursor class.
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#
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#------------------------------------------------------------------------
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"""Manage shelves of pickled objects using bsddb database files for the
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storage.
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"""
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#------------------------------------------------------------------------
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import cPickle
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try:
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from UserDict import DictMixin
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except ImportError:
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# DictMixin is new in Python 2.3
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class DictMixin: pass
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import db
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#------------------------------------------------------------------------
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def open(filename, flags=db.DB_CREATE, mode=0660, filetype=db.DB_HASH,
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dbenv=None, dbname=None):
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"""
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A simple factory function for compatibility with the standard
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shleve.py module. It can be used like this, where key is a string
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and data is a pickleable object:
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from bsddb import dbshelve
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db = dbshelve.open(filename)
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db[key] = data
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db.close()
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"""
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if type(flags) == type(''):
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sflag = flags
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if sflag == 'r':
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flags = db.DB_RDONLY
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elif sflag == 'rw':
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flags = 0
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elif sflag == 'w':
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flags = db.DB_CREATE
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elif sflag == 'c':
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flags = db.DB_CREATE
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elif sflag == 'n':
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flags = db.DB_TRUNCATE | db.DB_CREATE
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else:
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raise db.DBError, "flags should be one of 'r', 'w', 'c' or 'n' or use the bsddb.db.DB_* flags"
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d = DBShelf(dbenv)
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d.open(filename, dbname, filetype, flags, mode)
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return d
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#---------------------------------------------------------------------------
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class DBShelf(DictMixin):
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"""A shelf to hold pickled objects, built upon a bsddb DB object. It
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automatically pickles/unpickles data objects going to/from the DB.
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"""
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def __init__(self, dbenv=None):
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self.db = db.DB(dbenv)
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self.binary = 1
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def __del__(self):
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self.close()
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def __getattr__(self, name):
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"""Many methods we can just pass through to the DB object.
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(See below)
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"""
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return getattr(self.db, name)
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#-----------------------------------
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# Dictionary access methods
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def __len__(self):
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return len(self.db)
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def __getitem__(self, key):
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data = self.db[key]
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return cPickle.loads(data)
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def __setitem__(self, key, value):
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data = cPickle.dumps(value, self.binary)
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self.db[key] = data
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def __delitem__(self, key):
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del self.db[key]
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def keys(self, txn=None):
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if txn != None:
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return self.db.keys(txn)
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else:
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return self.db.keys()
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def items(self, txn=None):
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if txn != None:
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items = self.db.items(txn)
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else:
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items = self.db.items()
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newitems = []
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for k, v in items:
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newitems.append( (k, cPickle.loads(v)) )
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return newitems
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def values(self, txn=None):
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if txn != None:
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values = self.db.values(txn)
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else:
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values = self.db.values()
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return map(cPickle.loads, values)
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#-----------------------------------
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# Other methods
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def __append(self, value, txn=None):
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data = cPickle.dumps(value, self.binary)
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return self.db.append(data, txn)
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def append(self, value, txn=None):
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if self.get_type() != db.DB_RECNO:
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self.append = self.__append
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return self.append(value, txn=txn)
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raise db.DBError, "append() only supported when dbshelve opened with filetype=dbshelve.db.DB_RECNO"
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def associate(self, secondaryDB, callback, flags=0):
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def _shelf_callback(priKey, priData, realCallback=callback):
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data = cPickle.loads(priData)
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return realCallback(priKey, data)
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return self.db.associate(secondaryDB, _shelf_callback, flags)
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#def get(self, key, default=None, txn=None, flags=0):
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def get(self, *args, **kw):
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# We do it with *args and **kw so if the default value wasn't
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# given nothing is passed to the extension module. That way
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# an exception can be raised if set_get_returns_none is turned
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# off.
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data = apply(self.db.get, args, kw)
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try:
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return cPickle.loads(data)
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except (TypeError, cPickle.UnpicklingError):
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return data # we may be getting the default value, or None,
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# so it doesn't need unpickled.
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def get_both(self, key, value, txn=None, flags=0):
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data = cPickle.dumps(value, self.binary)
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data = self.db.get(key, data, txn, flags)
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return cPickle.loads(data)
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def cursor(self, txn=None, flags=0):
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c = DBShelfCursor(self.db.cursor(txn, flags))
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c.binary = self.binary
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return c
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def put(self, key, value, txn=None, flags=0):
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data = cPickle.dumps(value, self.binary)
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return self.db.put(key, data, txn, flags)
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def join(self, cursorList, flags=0):
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raise NotImplementedError
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#----------------------------------------------
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# Methods allowed to pass-through to self.db
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#
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# close, delete, fd, get_byteswapped, get_type, has_key,
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# key_range, open, remove, rename, stat, sync,
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# upgrade, verify, and all set_* methods.
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#---------------------------------------------------------------------------
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class DBShelfCursor:
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"""
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"""
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def __init__(self, cursor):
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self.dbc = cursor
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def __del__(self):
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self.close()
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def __getattr__(self, name):
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"""Some methods we can just pass through to the cursor object. (See below)"""
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return getattr(self.dbc, name)
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#----------------------------------------------
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def dup(self, flags=0):
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return DBShelfCursor(self.dbc.dup(flags))
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def put(self, key, value, flags=0):
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data = cPickle.dumps(value, self.binary)
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return self.dbc.put(key, data, flags)
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def get(self, *args):
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count = len(args) # a method overloading hack
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method = getattr(self, 'get_%d' % count)
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apply(method, args)
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def get_1(self, flags):
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rec = self.dbc.get(flags)
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return self._extract(rec)
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def get_2(self, key, flags):
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rec = self.dbc.get(key, flags)
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return self._extract(rec)
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def get_3(self, key, value, flags):
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data = cPickle.dumps(value, self.binary)
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rec = self.dbc.get(key, flags)
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return self._extract(rec)
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def current(self, flags=0): return self.get_1(flags|db.DB_CURRENT)
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def first(self, flags=0): return self.get_1(flags|db.DB_FIRST)
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def last(self, flags=0): return self.get_1(flags|db.DB_LAST)
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def next(self, flags=0): return self.get_1(flags|db.DB_NEXT)
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def prev(self, flags=0): return self.get_1(flags|db.DB_PREV)
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def consume(self, flags=0): return self.get_1(flags|db.DB_CONSUME)
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def next_dup(self, flags=0): return self.get_1(flags|db.DB_NEXT_DUP)
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def next_nodup(self, flags=0): return self.get_1(flags|db.DB_NEXT_NODUP)
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def prev_nodup(self, flags=0): return self.get_1(flags|db.DB_PREV_NODUP)
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def get_both(self, key, value, flags=0):
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data = cPickle.dumps(value, self.binary)
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rec = self.dbc.get_both(key, flags)
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return self._extract(rec)
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def set(self, key, flags=0):
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rec = self.dbc.set(key, flags)
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return self._extract(rec)
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def set_range(self, key, flags=0):
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rec = self.dbc.set_range(key, flags)
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return self._extract(rec)
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def set_recno(self, recno, flags=0):
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rec = self.dbc.set_recno(recno, flags)
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return self._extract(rec)
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set_both = get_both
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def _extract(self, rec):
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if rec is None:
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return None
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else:
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key, data = rec
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return key, cPickle.loads(data)
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#----------------------------------------------
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# Methods allowed to pass-through to self.dbc
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#
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# close, count, delete, get_recno, join_item
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#---------------------------------------------------------------------------
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