Create the dbm package from PEP 3108. #2881.

1 files changed, 0 insertions, 255 deletions

diff --git a/Lib/dumbdbm.py b/Lib/dumbdbm.py
deleted file mode 100644
index 8d58f87..0000000
--- a/Lib/dumbdbm.py
+++ /dev/null
@@ -1,255 +0,0 @@
-"""A dumb and slow but simple dbm clone.
-
-For database spam, spam.dir contains the index (a text file),
-spam.bak *may* contain a backup of the index (also a text file),
-while spam.dat contains the data (a binary file).
-
-XXX TO DO:
-
-- seems to contain a bug when updating...
-
-- reclaim free space (currently, space once occupied by deleted or expanded
-items is never reused)
-
-- support concurrent access (currently, if two processes take turns making
-updates, they can mess up the index)
-
-- support efficient access to large databases (currently, the whole index
-is read when the database is opened, and some updates rewrite the whole index)
-
-- support opening for read-only (flag = 'm')
-
-"""
-
-import io as _io
-import os as _os
-import collections
-
-_BLOCKSIZE = 512
-
-error = IOError                         # For anydbm
-
-class _Database(collections.MutableMapping):
-
-    # The on-disk directory and data files can remain in mutually
-    # inconsistent states for an arbitrarily long time (see comments
-    # at the end of __setitem__).  This is only repaired when _commit()
-    # gets called.  One place _commit() gets called is from __del__(),
-    # and if that occurs at program shutdown time, module globals may
-    # already have gotten rebound to None.  Since it's crucial that
-    # _commit() finish successfully, we can't ignore shutdown races
-    # here, and _commit() must not reference any globals.
-    _os = _os       # for _commit()
-    _io = _io       # for _commit()
-
-    def __init__(self, filebasename, mode):
-        self._mode = mode
-
-        # The directory file is a text file.  Each line looks like
-        #    "%r, (%d, %d)\n" % (key, pos, siz)
-        # where key is the string key, pos is the offset into the dat
-        # file of the associated value's first byte, and siz is the number
-        # of bytes in the associated value.
-        self._dirfile = filebasename + '.dir'
-
-        # The data file is a binary file pointed into by the directory
-        # file, and holds the values associated with keys.  Each value
-        # begins at a _BLOCKSIZE-aligned byte offset, and is a raw
-        # binary 8-bit string value.
-        self._datfile = filebasename + '.dat'
-        self._bakfile = filebasename + '.bak'
-
-        # The index is an in-memory dict, mirroring the directory file.
-        self._index = None  # maps keys to (pos, siz) pairs
-
-        # Mod by Jack: create data file if needed
-        try:
-            f = _io.open(self._datfile, 'r')
-        except IOError:
-            f = _io.open(self._datfile, 'w')
-            self._chmod(self._datfile)
-        f.close()
-        self._update()
-
-    # Read directory file into the in-memory index dict.
-    def _update(self):
-        self._index = {}
-        try:
-            f = _io.open(self._dirfile, 'r')
-        except IOError:
-            pass
-        else:
-            for line in f:
-                line = line.rstrip()
-                key, pos_and_siz_pair = eval(line)
-                self._index[key] = pos_and_siz_pair
-            f.close()
-
-    # Write the index dict to the directory file.  The original directory
-    # file (if any) is renamed with a .bak extension first.  If a .bak
-    # file currently exists, it's deleted.
-    def _commit(self):
-        # CAUTION:  It's vital that _commit() succeed, and _commit() can
-        # be called from __del__().  Therefore we must never reference a
-        # global in this routine.
-        if self._index is None:
-            return  # nothing to do
-
-        try:
-            self._os.unlink(self._bakfile)
-        except self._os.error:
-            pass
-
-        try:
-            self._os.rename(self._dirfile, self._bakfile)
-        except self._os.error:
-            pass
-
-        f = self._io.open(self._dirfile, 'w')
-        self._chmod(self._dirfile)
-        for key, pos_and_siz_pair in self._index.items():
-            f.write("%r, %r\n" % (key, pos_and_siz_pair))
-        f.close()
-
-    sync = _commit
-
-    def __getitem__(self, key):
-        key = key.decode("latin-1")
-        pos, siz = self._index[key]     # may raise KeyError
-        f = _io.open(self._datfile, 'rb')
-        f.seek(pos)
-        dat = f.read(siz)
-        f.close()
-        return dat
-
-    # Append val to the data file, starting at a _BLOCKSIZE-aligned
-    # offset.  The data file is first padded with NUL bytes (if needed)
-    # to get to an aligned offset.  Return pair
-    #     (starting offset of val, len(val))
-    def _addval(self, val):
-        f = _io.open(self._datfile, 'rb+')
-        f.seek(0, 2)
-        pos = int(f.tell())
-        npos = ((pos + _BLOCKSIZE - 1) // _BLOCKSIZE) * _BLOCKSIZE
-        f.write(b'\0'*(npos-pos))
-        pos = npos
-        f.write(val)
-        f.close()
-        return (pos, len(val))
-
-    # Write val to the data file, starting at offset pos.  The caller
-    # is responsible for ensuring that there's enough room starting at
-    # pos to hold val, without overwriting some other value.  Return
-    # pair (pos, len(val)).
-    def _setval(self, pos, val):
-        f = _io.open(self._datfile, 'rb+')
-        f.seek(pos)
-        f.write(val)
-        f.close()
-        return (pos, len(val))
-
-    # key is a new key whose associated value starts in the data file
-    # at offset pos and with length siz.  Add an index record to
-    # the in-memory index dict, and append one to the directory file.
-    def _addkey(self, key, pos_and_siz_pair):
-        self._index[key] = pos_and_siz_pair
-        f = _io.open(self._dirfile, 'a')
-        self._chmod(self._dirfile)
-        f.write("%r, %r\n" % (key, pos_and_siz_pair))
-        f.close()
-
-    def __setitem__(self, key, val):
-        if not isinstance(key, bytes):
-            raise TypeError("keys must be bytes")
-        key = key.decode("latin-1") # hashable bytes
-        if not isinstance(val, (bytes, bytearray)):
-            raise TypeError("values must be byte strings")
-        if key not in self._index:
-            self._addkey(key, self._addval(val))
-        else:
-            # See whether the new value is small enough to fit in the
-            # (padded) space currently occupied by the old value.
-            pos, siz = self._index[key]
-            oldblocks = (siz + _BLOCKSIZE - 1) // _BLOCKSIZE
-            newblocks = (len(val) + _BLOCKSIZE - 1) // _BLOCKSIZE
-            if newblocks <= oldblocks:
-                self._index[key] = self._setval(pos, val)
-            else:
-                # The new value doesn't fit in the (padded) space used
-                # by the old value.  The blocks used by the old value are
-                # forever lost.
-                self._index[key] = self._addval(val)
-
-            # Note that _index may be out of synch with the directory
-            # file now:  _setval() and _addval() don't update the directory
-            # file.  This also means that the on-disk directory and data
-            # files are in a mutually inconsistent state, and they'll
-            # remain that way until _commit() is called.  Note that this
-            # is a disaster (for the database) if the program crashes
-            # (so that _commit() never gets called).
-
-    def __delitem__(self, key):
-        key = key.decode("latin-1")
-        # The blocks used by the associated value are lost.
-        del self._index[key]
-        # XXX It's unclear why we do a _commit() here (the code always
-        # XXX has, so I'm not changing it).  _setitem__ doesn't try to
-        # XXX keep the directory file in synch.  Why should we?  Or
-        # XXX why shouldn't __setitem__?
-        self._commit()
-
-    def keys(self):
-        return [key.encode("latin-1") for key in self._index.keys()]
-
-    def items(self):
-        return [(key.encode("latin-1"), self[key.encode("latin-1")])
-                for key in self._index.keys()]
-
-    def __contains__(self, key):
-        key = key.decode("latin-1")
-        return key in self._index
-
-    def iterkeys(self):
-        return iter(self._index.keys())
-    __iter__ = iterkeys
-
-    def __len__(self):
-        return len(self._index)
-
-    def close(self):
-        self._commit()
-        self._index = self._datfile = self._dirfile = self._bakfile = None
-
-    __del__ = close
-
-    def _chmod (self, file):
-        if hasattr(self._os, 'chmod'):
-            self._os.chmod(file, self._mode)
-
-
-def open(file, flag=None, mode=0o666):
-    """Open the database file, filename, and return corresponding object.
-
-    The flag argument, used to control how the database is opened in the
-    other DBM implementations, is ignored in the dumbdbm module; the
-    database is always opened for update, and will be created if it does
-    not exist.
-
-    The optional mode argument is the UNIX mode of the file, used only when
-    the database has to be created.  It defaults to octal code 0o666 (and
-    will be modified by the prevailing umask).
-
-    """
-    # flag argument is currently ignored
-
-    # Modify mode depending on the umask
-    try:
-        um = _os.umask(0)
-        _os.umask(um)
-    except AttributeError:
-        pass
-    else:
-        # Turn off any bits that are set in the umask
-        mode = mode & (~um)
-
-    return _Database(file, mode)