C++ (Cpp) MSet::get_matches_upper_bound Examples

Example #1

File: XapianEngine.cpp Project: BackupTheBerlios/pinot-svn

bool XapianEngine::queryDatabase(Xapian::Database *pIndex, Xapian::Query &query,
	const string &stemLanguage, unsigned int startDoc, const QueryProperties &queryProps)
{
	Timer timer;
	unsigned int maxResultsCount = queryProps.getMaximumResultsCount();
	bool completedQuery = false;

	if (pIndex == NULL)
	{
		return false;
	}

	// Start an enquire session on the database
	Xapian::Enquire enquire(*pIndex);

	timer.start();
	try
	{
		AbstractGenerator abstractGen(pIndex, 50);
		vector<string> seedTerms;

		// Give the query object to the enquire session
		enquire.set_query(query);
		// How should results be sorted ?
		if (queryProps.getSortOrder() == QueryProperties::RELEVANCE)
		{
			// By relevance, only
			enquire.set_sort_by_relevance_then_value(4);
#ifdef DEBUG
			cout << "XapianEngine::queryDatabase: sorting by relevance first" << endl;
#endif
		}
		else if (queryProps.getSortOrder() == QueryProperties::DATE)
		{
			// By date, and then by relevance
			enquire.set_sort_by_value_then_relevance(4);
#ifdef DEBUG
			cout << "XapianEngine::queryDatabase: sorting by date and time first" << endl;
#endif
		}

		// Get the top results of the query
		Xapian::MSet matches = enquire.get_mset(startDoc, maxResultsCount, (2 * maxResultsCount) + 1);
		m_resultsCountEstimate = matches.get_matches_estimated();
		if (matches.empty() == false)
		{
#ifdef DEBUG
			cout << "XapianEngine::queryDatabase: found " << matches.size() << "/" << maxResultsCount
				<< " results found from position " << startDoc << endl;
			cout << "XapianEngine::queryDatabase: estimated " << matches.get_matches_lower_bound()
				<< "/" << m_resultsCountEstimate << "/" << matches.get_matches_upper_bound() << endl;
#endif

			// Get the results
			for (Xapian::MSetIterator mIter = matches.begin(); mIter != matches.end(); ++mIter)
			{
				Xapian::docid docId = *mIter;
				Xapian::Document doc(mIter.get_document());

				// What terms did this document match ?
				seedTerms.clear();
				for (Xapian::TermIterator termIter = enquire.get_matching_terms_begin(docId);
					termIter != enquire.get_matching_terms_end(docId); ++termIter)
				{
					char firstChar = (*termIter)[0];

					if (isupper(((int)firstChar)) == 0)
					{
						seedTerms.push_back(*termIter);
#ifdef DEBUG
						cout << "XapianEngine::queryDatabase: matched term " << *termIter << endl;
#endif
					}
					else if (firstChar == 'Z')
					{
						string stemmed((*termIter).substr(1));
						string::size_type stemmedLen = stemmed.length();

						// Which of this document's terms stem to this ?
						Xapian::TermIterator docTermIter = pIndex->termlist_begin(docId);
						if (docTermIter != pIndex->termlist_end(docId))
						{
							for (docTermIter.skip_to(stemmed);
								docTermIter != pIndex->termlist_end(docId); ++docTermIter)
							{
								// Is this a potential unstem ?
								if (strncasecmp((*docTermIter).c_str(), stemmed.c_str(), stemmedLen) != 0)
								{
									// No, no point looking at the next terms
									break;
								}
#ifdef DEBUG
								cout << "XapianEngine::queryDatabase: matched unstem " << *docTermIter << endl;
#endif

								// FIXME: check this term stems to stemmed !
								seedTerms.push_back(*docTermIter); 
							}
						}
					}
				}

				DocumentInfo thisResult;
				thisResult.setExtract(abstractGen.generateAbstract(docId, seedTerms));
				thisResult.setScore((float)mIter.get_percent());

#ifdef DEBUG
				cout << "XapianEngine::queryDatabase: found document ID " << docId << endl;
#endif
				XapianDatabase::recordToProps(doc.get_data(), &thisResult);
				// XapianDatabase stored the language in English
				thisResult.setLanguage(Languages::toLocale(thisResult.getLanguage()));

				string url(thisResult.getLocation());
				if (url.empty() == true)
				{
					// Hmmm this shouldn't be empty...
					// Use this instead, even though the document isn't cached in the index
					thisResult.setLocation(XapianDatabase::buildUrl(m_databaseName, docId));
				}

				// We don't know the index ID, just the document ID
				thisResult.setIsIndexed(0, docId);

				// Add this result
				m_resultsList.push_back(thisResult);
			}
		}

		completedQuery = true;
	}
	catch (const Xapian::Error &error)
	{
		cerr << "Couldn't run query: " << error.get_type() << ": " << error.get_msg() << endl;
	}
	cout << "Ran query \"" << queryProps.getFreeQuery() << "\" in " << timer.stop() << " ms" << endl;

	try
	{
		m_expandTerms.clear();

		// Expand the query ?
		if (m_expandDocuments.empty() == false)
		{
			Xapian::RSet expandDocs;

			for (set<string>::const_iterator docIter = m_expandDocuments.begin();
				docIter != m_expandDocuments.end(); ++docIter)
			{
				string uniqueTerm(string("U") + XapianDatabase::limitTermLength(Url::escapeUrl(Url::canonicalizeUrl(*docIter)), true));

				// Only one document may have this term
				Xapian::PostingIterator postingIter = pIndex->postlist_begin(uniqueTerm);
				if (postingIter != pIndex->postlist_end(uniqueTerm))
				{
					expandDocs.add_document(*postingIter);
				}
			}
#ifdef DEBUG
			cout << "XapianEngine::queryDatabase: expand from " << expandDocs.size() << " documents" << endl;
#endif

			// Get 10 non-prefixed terms
			string allowedPrefixes("RS");
			TermDecider expandDecider(pIndex, ((stemLanguage.empty() == true) ? NULL : &m_stemmer),
				FileStopper::get_stopper(Languages::toCode(stemLanguage)),
				allowedPrefixes, query);
			Xapian::ESet expandTerms = enquire.get_eset(10, expandDocs, &expandDecider);
#ifdef DEBUG
			cout << "XapianEngine::queryDatabase: " << expandTerms.size() << " expand terms" << endl;
#endif
			for (Xapian::ESetIterator termIter = expandTerms.begin();
				termIter != expandTerms.end(); ++termIter)
			{
				string expandTerm(*termIter);
				char firstChar = expandTerm[0];

				// Is this prefixed ?
				if (allowedPrefixes.find(firstChar) != string::npos)
				{
					expandTerm.erase(0, 1);
				}

				m_expandTerms.insert(expandTerm);
			}
		}
	}
	catch (const Xapian::Error &error)
	{
		cerr << "Couldn't run query: " << error.get_type() << ": " << error.get_msg() << endl;
	}

	// Be tolerant of errors as long as we got some results
	if ((completedQuery == true) ||
		(m_resultsList.empty() == false))
	{
		return true;
	}

	return false;
}