# Source code for BTrees.Interfaces

```
##############################################################################
#
# Copyright (c) 2001, 2002 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE
#
##############################################################################
from zope.interface import Interface, Attribute
[docs]class ICollection(Interface):
def clear():
"""Remove all of the items from the collection."""
def __nonzero__():
"""Check if the collection is non-empty.
Return a true value if the collection is non-empty and a
false value otherwise.
"""
[docs]class IReadSequence(Interface):
def __getitem__(index):
"""Return the value at the given index.
An IndexError is raised if the index cannot be found.
"""
def __getslice__(index1, index2):
"""Return a subsequence from the original sequence.
The subsequence includes the items from index1 up to, but not
including, index2.
"""
[docs]class IKeyed(ICollection):
def has_key(key):
"""Check whether the object has an item with the given key.
Return a true value if the key is present, else a false value.
"""
def keys(min=None, max=None, excludemin=False, excludemax=False):
"""Return an IReadSequence containing the keys in the collection.
The type of the IReadSequence is not specified. It could be a list
or a tuple or some other type.
All arguments are optional, and may be specified as keyword
arguments, or by position.
If a min is specified, then output is constrained to keys greater
than or equal to the given min, and, if excludemin is specified and
true, is further constrained to keys strictly greater than min. A
min value of None is ignored. If min is None or not specified, and
excludemin is true, the smallest key is excluded.
If a max is specified, then output is constrained to keys less than
or equal to the given max, and, if excludemax is specified and
true, is further constrained to keys strictly less than max. A max
value of None is ignored. If max is None or not specified, and
excludemax is true, the largest key is excluded.
"""
def maxKey(key=None):
"""Return the maximum key.
If a key argument if provided and not None, return the largest key
that is less than or equal to the argument. Raise an exception if
no such key exists.
"""
def minKey(key=None):
"""Return the minimum key.
If a key argument if provided and not None, return the smallest key
that is greater than or equal to the argument. Raise an exception
if no such key exists.
"""
[docs]class ISetMutable(IKeyed):
def insert(key):
"""Add the key (value) to the set.
If the key was already in the set, return 0, otherwise return 1.
"""
def remove(key):
"""Remove the key from the set.
Raises KeyError if key is not in the set.
"""
def update(seq):
"""Add the items from the given sequence to the set."""
[docs]class ISized(Interface):
"""An object that supports __len__."""
def __len__():
"""Return the number of items in the container."""
[docs]class IKeySequence(IKeyed, ISized):
def __getitem__(index):
"""Return the key in the given index position.
This allows iteration with for loops and use in functions,
like map and list, that read sequences.
"""
[docs]class IMinimalDictionary(ISized, IKeyed):
def get(key, default):
"""Get the value associated with the given key.
Return the default if has_key(key) is false.
"""
def __getitem__(key):
"""Get the value associated with the given key.
Raise KeyError if has_key(key) is false.
"""
def __setitem__(key, value):
"""Set the value associated with the given key."""
def __delitem__(key):
"""Delete the value associated with the given key.
Raise KeyError if has_key(key) is false.
"""
def values(min=None, max=None, excludemin=False, excludemax=False):
"""Return an IReadSequence containing the values in the collection.
The type of the IReadSequence is not specified. It could be a list
or a tuple or some other type.
All arguments are optional, and may be specified as keyword
arguments, or by position.
If a min is specified, then output is constrained to values whose
keys are greater than or equal to the given min, and, if excludemin
is specified and true, is further constrained to values whose keys
are strictly greater than min. A min value of None is ignored. If
min is None or not specified, and excludemin is true, the value
corresponding to the smallest key is excluded.
If a max is specified, then output is constrained to values whose
keys are less than or equal to the given max, and, if excludemax is
specified and true, is further constrained to values whose keys are
strictly less than max. A max value of None is ignored. If max is
None or not specified, and excludemax is true, the value
corresponding to the largest key is excluded.
"""
def items(min=None, max=None, excludemin=False, excludemax=False):
"""Return an IReadSequence containing the items in the collection.
An item is a 2-tuple, a (key, value) pair.
The type of the IReadSequence is not specified. It could be a list
or a tuple or some other type.
All arguments are optional, and may be specified as keyword
arguments, or by position.
If a min is specified, then output is constrained to items whose
keys are greater than or equal to the given min, and, if excludemin
is specified and true, is further constrained to items whose keys
are strictly greater than min. A min value of None is ignored. If
min is None or not specified, and excludemin is true, the item with
the smallest key is excluded.
If a max is specified, then output is constrained to items whose
keys are less than or equal to the given max, and, if excludemax is
specified and true, is further constrained to items whose keys are
strictly less than max. A max value of None is ignored. If max is
None or not specified, and excludemax is true, the item with the
largest key is excluded.
"""
[docs]class IDictionaryIsh(IMinimalDictionary):
def update(collection):
"""Add the items from the given collection object to the collection.
The input collection must be a sequence of (key, value) 2-tuples,
or an object with an 'items' method that returns a sequence of
(key, value) pairs.
"""
def byValue(minValue):
"""Return a sequence of (value, key) pairs, sorted by value.
Values < minValue are omitted and other values are "normalized" by
the minimum value. This normalization may be a noop, but, for
integer values, the normalization is division.
"""
def setdefault(key, d):
"""D.setdefault(k, d) -> D.get(k, d), also set D[k]=d if k not in D.
Return the value like get() except that if key is missing, d is both
returned and inserted into the dictionary as the value of k.
Note that, unlike as for Python's dict.setdefault(), d is not
optional. Python defaults d to None, but that doesn't make sense
for mappings that can't have None as a value (for example, an
IIBTree can have only integers as values).
"""
def pop(key, d):
"""D.pop(k[, d]) -> v, remove key and return the corresponding value.
If key is not found, d is returned if given, otherwise KeyError is
raised.
"""
[docs]class IBTree(IDictionaryIsh):
def insert(key, value):
"""Insert a key and value into the collection.
If the key was already in the collection, then there is no
change and 0 is returned.
If the key was not already in the collection, then the item is
added and 1 is returned.
This method is here to allow one to generate random keys and
to insert and test whether the key was there in one operation.
A standard idiom for generating new keys will be::
key = generate_key()
while not t.insert(key, value):
key=generate_key()
"""
[docs]class IMerge(Interface):
"""Object with methods for merging sets, buckets, and trees.
These methods are supplied in modules that define collection
classes with particular key and value types. The operations apply
only to collections from the same module. For example, the
IIBTree.union can only be used with IIBTree.IIBTree,
IIBTree.IIBucket, IIBTree.IISet, and IIBTree.IITreeSet.
The implementing module has a value type. The IOBTree and OOBTree
modules have object value type. The IIBTree and OIBTree modules
have integer value types. Other modules may be defined in the
future that have other value types.
The individual types are classified into set (Set and TreeSet) and
mapping (Bucket and BTree) types.
"""
def difference(c1, c2):
"""Return the keys or items in c1 for which there is no key in c2.
If c1 is None, then None is returned. If c2 is None, then c1
is returned.
If neither c1 nor c2 is None, the output is a Set if c1 is a Set or
TreeSet, and is a Bucket if c1 is a Bucket or BTree.
"""
def union(c1, c2):
"""Compute the Union of c1 and c2.
If c1 is None, then c2 is returned, otherwise, if c2 is None,
then c1 is returned.
The output is a Set containing keys from the input
collections.
"""
def intersection(c1, c2):
"""Compute the intersection of c1 and c2.
If c1 is None, then c2 is returned, otherwise, if c2 is None,
then c1 is returned.
The output is a Set containing matching keys from the input
collections.
"""
[docs]class IBTreeModule(Interface):
"""These are available in all modules (IOBTree, OIBTree, OOBTree, IIBTree,
IFBTree, LFBTree, LOBTree, OLBTree, and LLBTree).
"""
BTree = Attribute(
"""The IBTree for this module.
Also available as [prefix]BTree, as in IOBTree.""")
Bucket = Attribute(
"""The leaf-node data buckets used by the BTree.
(IBucket is not currently defined in this file, but is essentially
IDictionaryIsh, with the exception of __nonzero__, as of this
writing.)
Also available as [prefix]Bucket, as in IOBucket.""")
TreeSet = Attribute(
"""The ITreeSet for this module.
Also available as [prefix]TreeSet, as in IOTreeSet.""")
Set = Attribute(
"""The ISet for this module: the leaf-node data buckets used by the
TreeSet.
Also available as [prefix]BTree, as in IOSet.""")
[docs]class IIMerge(IMerge):
"""Merge collections with integer value type.
A primary intent is to support operations with no or integer
values, which are used as "scores" to rate indiviual keys. That
is, in this context, a BTree or Bucket is viewed as a set with
scored keys, using integer scores.
"""
def weightedUnion(c1, c2, weight1=1, weight2=1):
"""Compute the weighted union of c1 and c2.
If c1 and c2 are None, the output is (0, None).
If c1 is None and c2 is not None, the output is (weight2, c2).
If c1 is not None and c2 is None, the output is (weight1, c1).
Else, and hereafter, c1 is not None and c2 is not None.
If c1 and c2 are both sets, the output is 1 and the (unweighted)
union of the sets.
Else the output is 1 and a Bucket whose keys are the union of c1 and
c2's keys, and whose values are::
v1*weight1 + v2*weight2
where:
v1 is 0 if the key is not in c1
1 if the key is in c1 and c1 is a set
c1[key] if the key is in c1 and c1 is a mapping
v2 is 0 if the key is not in c2
1 if the key is in c2 and c2 is a set
c2[key] if the key is in c2 and c2 is a mapping
Note that c1 and c2 must be collections.
"""
def weightedIntersection(c1, c2, weight1=1, weight2=1):
"""Compute the weighted intersection of c1 and c2.
If c1 and c2 are None, the output is (0, None).
If c1 is None and c2 is not None, the output is (weight2, c2).
If c1 is not None and c2 is None, the output is (weight1, c1).
Else, and hereafter, c1 is not None and c2 is not None.
If c1 and c2 are both sets, the output is the sum of the weights
and the (unweighted) intersection of the sets.
Else the output is 1 and a Bucket whose keys are the intersection of
c1 and c2's keys, and whose values are::
v1*weight1 + v2*weight2
where:
v1 is 1 if c1 is a set
c1[key] if c1 is a mapping
v2 is 1 if c2 is a set
c2[key] if c2 is a mapping
Note that c1 and c2 must be collections.
"""
[docs]class IMergeIntegerKey(IMerge):
"""IMerge-able objects with integer keys.
Concretely, this means the types in IOBTree and IIBTree.
"""
def multiunion(seq):
"""Return union of (zero or more) integer sets, as an integer set.
seq is a sequence of objects each convertible to an integer set.
These objects are convertible to an integer set:
+ An integer, which is added to the union.
+ A Set or TreeSet from the same module (for example, an
IIBTree.TreeSet for IIBTree.multiunion()). The elements of the
set are added to the union.
+ A Bucket or BTree from the same module (for example, an
IOBTree.IOBTree for IOBTree.multiunion()). The keys of the
mapping are added to the union.
The union is returned as a Set from the same module (for example,
IIBTree.multiunion() returns an IIBTree.IISet).
The point to this method is that it can run much faster than
doing a sequence of two-input union() calls. Under the covers,
all the integers in all the inputs are sorted via a single
linear-time radix sort, then duplicates are removed in a second
linear-time pass.
"""
[docs]class IBTreeFamily(Interface):
"""the 64-bit or 32-bit family"""
IO = Attribute('The IIntegerObjectBTreeModule for this family')
OI = Attribute('The IObjectIntegerBTreeModule for this family')
II = Attribute('The IIntegerIntegerBTreeModule for this family')
IF = Attribute('The IIntegerFloatBTreeModule for this family')
OO = Attribute('The IObjectObjectBTreeModule for this family')
maxint = Attribute('The maximum integer storable in this family')
minint = Attribute('The minimum integer storable in this family')
[docs]class IIntegerObjectBTreeModule(IBTreeModule, IMerge):
"""keys, or set values, are integers; values are objects.
describes IOBTree and LOBTree"""
family = Attribute('The IBTreeFamily of this module')
[docs]class IObjectIntegerBTreeModule(IBTreeModule, IIMerge):
"""keys, or set values, are objects; values are integers.
Object keys (and set values) must sort reliably (for instance, *not* on
object id)! Homogenous key types recommended.
describes OIBTree and LOBTree"""
family = Attribute('The IBTreeFamily of this module')
[docs]class IIntegerIntegerBTreeModule(IBTreeModule, IIMerge, IMergeIntegerKey):
"""keys, or set values, are integers; values are also integers.
describes IIBTree and LLBTree"""
family = Attribute('The IBTreeFamily of this module')
[docs]class IObjectObjectBTreeModule(IBTreeModule, IMerge):
"""keys, or set values, are objects; values are also objects.
Object keys (and set values) must sort reliably (for instance, *not* on
object id)! Homogenous key types recommended.
describes OOBTree"""
# Note that there's no ``family`` attribute; all families include
# the OO flavor of BTrees.
[docs]class IIntegerFloatBTreeModule(IBTreeModule, IMerge):
"""keys, or set values, are integers; values are floats.
describes IFBTree and LFBTree"""
family = Attribute('The IBTreeFamily of this module')
try:
from ZODB.POSException import BTreesConflictError
except ImportError:
class BTreesConflictError(ValueError):
@property
def reason(self):
return self.args[-1]
###############################################################
# IMPORTANT NOTE
#
# Getting the length of a BTree, TreeSet, or output of keys,
# values, or items of same is expensive. If you need to get the
# length, you need to maintain this separately.
#
# Eventually, I need to express this through the interfaces.
#
################################################################
```