[Zope-Checkins] CVS: Zope2 - GlobbingLexicon.py:1.1.2.1
andreas@digicool.com
andreas@digicool.com
Wed, 16 May 2001 11:29:43 -0400 (EDT)
Update of /cvs-repository/Zope2/lib/python/Products/PluginIndexes/TextIndex
In directory korak.digicool.com:/tmp/cvs-serv4020/Products/PluginIndexes/TextIndex
Added Files:
Tag: ajung-dropin-registry
GlobbingLexicon.py
Log Message:
moved
--- Added File GlobbingLexicon.py in package Zope2 ---
##############################################################################
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#############################################################################
from Lexicon import Lexicon
from Splitter import Splitter
from UnTextIndex import Or
import re, string
from BTrees.IIBTree import IISet, union, IITreeSet
from BTrees.OIBTree import OIBTree
from BTrees.IOBTree import IOBTree
from BTrees.OOBTree import OOBTree
from randid import randid
class GlobbingLexicon(Lexicon):
"""Lexicon which supports basic globbing function ('*' and '?').
This lexicon keeps several data structures around that are useful
for searching. They are:
'_lexicon' -- Contains the mapping from word => word_id
'_inverseLex' -- Contains the mapping from word_id => word
'_digrams' -- Contains a mapping from digram => word_id
Before going further, it is necessary to understand what a digram is,
as it is a core component of the structure of this lexicon. A digram
is a two-letter sequence in a word. For example, the word 'zope'
would be converted into the digrams::
['$z', 'zo', 'op', 'pe', 'e$']
where the '$' is a word marker. It is used at the beginning and end
of the words. Those digrams are significant.
"""
multi_wc = '*'
single_wc = '?'
eow = '$'
def __init__(self):
self.clear()
def clear(self):
self._lexicon = OIBTree()
self._inverseLex = IOBTree()
self._digrams = OOBTree()
def _convertBTrees(self, threshold=200):
Lexicon._convertBTrees(self, threshold)
if type(self._digrams) is OOBTree: return
from BTrees.convert import convert
_digrams=self._digrams
self._digrams=OOBTree()
self._digrams._p_jar=self._p_jar
convert(_digrams, self._digrams, threshold, IITreeSet)
def createDigrams(self, word):
"""Returns a list with the set of digrams in the word."""
digrams = []
digrams.append(self.eow + word[0]) # Mark the beginning
for i in range(1,len(word)):
digrams.append(word[i-1:i+1])
digrams[-1] = digrams[-1] + self.eow # Mark the end
return digrams
def getWordId(self, word):
"""Provided 'word', return the matching integer word id."""
if self._lexicon.has_key(word):
return self._lexicon[word]
else:
return self.assignWordId(word)
set = getWordId # Kludge for old code
def getWord(self, wid):
return self._inverseLex.get(wid, None)
def assignWordId(self, word):
"""Assigns a new word id to the provided word, and return it."""
# Double check it's not in the lexicon already, and if it is, just
# return it.
if self._lexicon.has_key(word):
return self._lexicon[word]
# Get word id. BBB Backward compat pain.
inverse=self._inverseLex
try: insert=inverse.insert
except AttributeError:
# we have an "old" BTree object
if inverse:
wid=inverse.keys()[-1]+1
else:
self._inverseLex=IOBTree()
wid=1
inverse[wid] = word
else:
# we have a "new" IOBTree object
wid=randid()
while not inverse.insert(wid, word):
wid=randid()
self._lexicon[word] = wid
# Now take all the digrams and insert them into the digram map.
for digram in self.createDigrams(word):
set = self._digrams.get(digram, None)
if set is None:
self._digrams[digram] = set = IISet()
set.insert(wid)
return wid
def get(self, pattern):
""" Query the lexicon for words matching a pattern."""
wc_set = [self.multi_wc, self.single_wc]
digrams = []
globbing = 0
for i in range(len(pattern)):
if pattern[i] in wc_set:
globbing = 1
continue
if i == 0:
digrams.insert(i, (self.eow + pattern[i]) )
digrams.append((pattern[i] + pattern[i+1]))
else:
try:
if pattern[i+1] not in wc_set:
digrams.append( pattern[i] + pattern[i+1] )
except IndexError:
digrams.append( (pattern[i] + self.eow) )
if not globbing:
result = self._lexicon.get(pattern, None)
if result is None:
return ()
return (result, )
## now get all of the intsets that contain the result digrams
result = None
for digram in digrams:
result=union(result, self._digrams.get(digram, None))
if not result:
return ()
else:
## now we have narrowed the list of possible candidates
## down to those words which contain digrams. However,
## some words may have been returned that match digrams,
## but do not match 'pattern'. This is because some words
## may contain all matching digrams, but in the wrong
## order.
expr = re.compile(self.createRegex(pattern))
words = []
hits = IISet()
for x in result:
if expr.match(self._inverseLex[x]):
hits.insert(x)
return hits
def __getitem__(self, word):
""" """
return self.get(word)
def query_hook(self, q):
"""expand wildcards"""
words = []
for w in q:
if ( (self.multi_wc in w) or
(self.single_wc in w) ):
wids = self.get(w)
for wid in wids:
if words:
words.append(Or)
words.append(wid)
else:
words.append(w)
# if words is empty, return something that will make textindex's
# __getitem__ return an empty result list
return words or ['']
def Splitter(self, astring, words=None):
""" wrap the splitter """
## don't do anything, less efficient but there's not much
## sense in stemming a globbing lexicon.
return Splitter(astring)
def createRegex(self, pat):
"""Translate a PATTERN to a regular expression.
There is no way to quote meta-characters.
"""
transTable = string.maketrans("", "")
# First, deal with mutli-character globbing
result = string.replace(pat, '*', '.*')
# Next, we need to deal with single-character globbing
result = string.replace(result, '?', '.?')
# Now, we need to remove all of the characters that
# are forbidden.
result = string.translate(result, transTable,
r'()&|!@#$%^{}\<>')
return "%s$" % result