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xapianIndexer.cpp
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xapianIndexer.cpp
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/*
* Copyright (C) 2021 Maneesh P M <manu.pm55@gmail.com>
* Copyright (C) 2018-2021 Matthieu Gautier <mgautier@kymeria.fr>
* Copyright (C) 2011 Emmanuel Engelhart <kelson@kiwix.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#include "xapianIndexer.h"
#include "libzim-resources.h"
#include "fs.h"
#include "tools.h"
#include "../constants.h"
#include <sstream>
#include <fstream>
#include <stdexcept>
#include <cassert>
using namespace zim::writer;
/* Constructor */
XapianIndexer::XapianIndexer(const std::string& indexPath, const std::string& language, IndexingMode indexingMode, const bool verbose)
: indexPath(indexPath),
language(language),
indexingMode(indexingMode)
{
/* Build ICU Local object to retrieve ISO-639 language code (from
ISO-639-3) */
icu::Locale languageLocale(language.c_str());
stemmer_language = languageLocale.getLanguage();
/* Read the stopwords */
std::string stopWord;
try {
this->stopwords = getResource("stopwords/" + language);
} catch(ResourceNotFound& e) {}
std::istringstream file(this->stopwords);
while (std::getline(file, stopWord, '\n')) {
this->stopper.add(stopWord);
}
}
XapianIndexer::~XapianIndexer()
{
if (!indexPath.empty()) {
try {
#ifndef _WIN32
//[TODO] Implement remove for windows
zim::DEFAULTFS::remove(indexPath + ".tmp");
zim::DEFAULTFS::remove(indexPath);
#endif
} catch (...) {
/* Do not raise */
}
}
}
/*
* `valuesmap` is a metadata associated with the Xapian database. We are using it
* to attach slot numbers of each document in the index to the value they are storing.
* These values and slot numbers are used in collapsing, filtering etc.
*
* Title index:
* Slot 0: Title of the article. Used in collapsing articles with same name.
* Slot 1: path/redirectPath of the article. Used in collapsing duplicates(redirects).
*
* Fulltext Index:
* Slot 0: Title of the article. Used in collapsing articles with same name.
* Slot 1: Word count of the article.
* Slot 2: Geo position of the article. Used for geo-filtering.
*
* `kind` metadata indicate whether the database is a title or a fulltext index.
*
* `data` metadata indicate the type of data stored in the index. A value of "fullPath"
* means the data stores the complete path with a namespace.
*/
void XapianIndexer::indexingPrelude()
{
writableDatabase = Xapian::WritableDatabase(indexPath + ".tmp", Xapian::DB_CREATE_OR_OVERWRITE | Xapian::DB_NO_TERMLIST);
switch (indexingMode) {
case IndexingMode::TITLE:
writableDatabase.set_metadata("valuesmap", "title:0;targetPath:1");
writableDatabase.set_metadata("kind", "title");
writableDatabase.set_metadata("data", "fullPath");
break;
case IndexingMode::FULL:
writableDatabase.set_metadata("valuesmap", "title:0;wordcount:1;geo.position:2");
writableDatabase.set_metadata("kind", "fulltext");
writableDatabase.set_metadata("data", "fullPath");
break;
}
writableDatabase.set_metadata("language", language);
writableDatabase.set_metadata("stopwords", stopwords);
}
namespace
{
size_t getTermCount(const Xapian::Document& d)
{
return std::distance(d.termlist_begin(), d.termlist_end());
}
} // unnamed namespace
/*
* For title index, index the full path with namespace as data of the document.
* The targetPath in valuesmap will store the path without namespace.
* TODO:
* Currently for title index we are storing path twice (redirectPath/path in
* valuesmap and path in index data). In the future, we want to keep only one of
* these(index data if possible) to reduce index size while supporting the
* collapse on path feature.
*/
void XapianIndexer::indexTitle(const std::string& path, const std::string& title, const std::string& targetPath)
{
assert(indexingMode == IndexingMode::TITLE);
Xapian::Stem stemmer;
Xapian::TermGenerator indexer;
indexer.set_flags(Xapian::TermGenerator::FLAG_CJK_NGRAM);
try {
stemmer = Xapian::Stem(stemmer_language);
indexer.set_stemmer(stemmer);
indexer.set_stemming_strategy(Xapian::TermGenerator::STEM_SOME);
} catch (...) {}
Xapian::Document currentDocument;
currentDocument.clear_values();
std::string fullPath = "C/" + path;
currentDocument.set_data(fullPath);
indexer.set_document(currentDocument);
std::string unaccentedTitle = zim::removeAccents(title);
currentDocument.add_value(0, title);
if (targetPath.empty()) {
currentDocument.add_value(1, path);
} else {
currentDocument.add_value(1, targetPath);
}
if (!unaccentedTitle.empty()) {
std::string anchoredTitle = ANCHOR_TERM + unaccentedTitle;
indexer.index_text(anchoredTitle, 1);
if ( getTermCount(currentDocument) == 1 ) {
// only ANCHOR_TERM was added, hence unaccentedTitle is made solely of
// non-word characters. Then add entire title as a single term.
currentDocument.remove_term(*currentDocument.termlist_begin());
currentDocument.add_term(unaccentedTitle);
}
}
/* add to the database */
writableDatabase.add_document(currentDocument);
empty = false;
}
void XapianIndexer::indexingPostlude()
{
this->writableDatabase.commit();
#if defined ENABLE_XAPIAN_FULLER
auto flags = Xapian::DBCOMPACT_SINGLE_FILE|Xapian::Compactor::FULLER;
#else
auto flags = Xapian::DBCOMPACT_SINGLE_FILE;
#endif
this->writableDatabase.compact(indexPath, flags);
this->writableDatabase.close();
}