Possibility of a memory leak in zim::Search::begin()

[veloman-yunkan]

queryParser in zim::Search::begin() may leak in case of an invalid query:

libzim/src/search.cpp

Lines 337 to 368 in e7fb949

	Xapian::QueryParser* queryParser = new Xapian::QueryParser();
	if (verbose) {
	std::cout << "Setup queryparser using language " << language << std::endl;
	}
	setup_queryParser(queryParser, internal->database, language, stopwords, suggestion_mode, hasNewSuggestionFormat);
	std::string prefix = "";
	unsigned flags = Xapian::QueryParser::FLAG_DEFAULT;
	if (suggestion_mode) {
	if (verbose) {
	std::cout << "Mark query as 'partial'" << std::endl;
	}
	flags |= Xapian::QueryParser::FLAG_PARTIAL;
	if ( !hasNewSuggestionFormat
	&& this->prefixes.find("S") != std::string::npos ) {
	if (verbose) {
	std::cout << "Searching in title namespace" << std::endl;
	}
	prefix = "S";
	}
	}
	Xapian::Query query;
	try {
	query = parse_query(queryParser, this->query, flags, prefix, suggestion_mode);
	} catch (Xapian::QueryParserError& e) {
	estimated_matches_number = 0;
	return nullptr;
	}
	if (verbose) {
	std::cout << "Parsed query '" << this->query << "' to " << query.get_description() << std::endl;
	}
	delete queryParser;

This can be fixed easily by making queryParser a stack-allocated object (currently the only justification for it being allocated dynamically could be the large value of sizeof(Xapian::QueryParser) which it isn't). Yet, it would be nice to refactor zim::Search::begin() along the way, breaking that 150+ line function down to smaller functions.