############################################################################## # # Copyright (c) 2002 Zope Corporation 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 Lexicon import Lexicon import Splitter 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 Products.PluginIndexes.TextIndex.TextIndex import Or,Op from Products.PluginIndexes.common.randid import randid from types import UnicodeType 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,useSplitter=None,extra=None): self.clear() self.useSplitter = useSplitter self.splitterParams = extra self.SplitterFunc = Splitter.getSplitter(self.useSplitter) 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.""" word = '$'+word+'$' return [ word[i:i+2] for i in range(len(word)-1)] 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.""" # single word pattern produce a slicing problem below. # Because the splitter throws away single characters we can # return an empty tuple here. if len(pattern)==1: return () 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""" ListType = type([]) i = len(q) - 1 while i >= 0: e = q[i] if isinstance(e, ListType): self.query_hook(e) elif isinstance(e, Op): pass elif ( (self.multi_wc in e) or (self.single_wc in e) ): wids = self.get(e) words = [] for wid in wids: if words: words.append(Or) words.append(wid) if not words: # if words is empty, return something that will make # textindex's __getitem__ return an empty result list words.append('') q[i] = words i = i - 1 return q def Splitter(self, astring, words=None, encoding="latin1"): """ wrap the splitter """ ## don't do anything, less efficient but there's not much ## sense in stemming a globbing lexicon. try: return self.SplitterFunc( astring, words, encoding=encoding, singlechar=self.splitterParams.splitterSingleChars, indexnumbers=self.splitterParams.splitterIndexNumbers, casefolding=self.splitterParams.splitterCasefolding ) except: return self.SplitterFunc(astring, words) def createRegex(self, pat): """Translate a PATTERN to a regular expression. There is no way to quote meta-characters. """ # Remove characters that are meaningful in a regex if not isinstance(pat, UnicodeType): transTable = string.maketrans("", "") result = string.translate(pat, transTable, r'()&|!@#$%^{}\<>.') else: transTable={} for ch in r'()&|!@#$%^{}\<>.': transTable[ord(ch)]=None result=pat.translate(transTable) # First, deal with multi-character globbing result = result.replace( '*', '.*') # Next, we need to deal with single-character globbing result = result.replace( '?', '.') return "%s$" % result