// TextSnippet.java
// -----------------
// (C) by Michael Peter Christen; mc@yacy.net
// first published on http://www.anomic.de
// Frankfurt, Germany, 2005
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// 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 2 of the License, or
// (at your option) 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package net.yacy.search.snippet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.regex.Pattern;
import net.yacy.cora.document.ASCII;
import net.yacy.cora.federate.yacy.CacheStrategy;
import net.yacy.cora.order.Base64Order;
import net.yacy.cora.protocol.ClientIdentification;
import net.yacy.cora.storage.ARC;
import net.yacy.cora.storage.ConcurrentARC;
import net.yacy.cora.storage.HandleSet;
import net.yacy.cora.util.ByteArray;
import net.yacy.cora.util.ByteBuffer;
import net.yacy.crawler.retrieval.Request;
import net.yacy.crawler.retrieval.Response;
import net.yacy.document.Document;
import net.yacy.document.Parser;
import net.yacy.document.SentenceReader;
import net.yacy.document.SnippetExtractor;
import net.yacy.document.WordTokenizer;
import net.yacy.document.parser.html.CharacterCoding;
import net.yacy.kelondro.data.meta.DigestURI;
import net.yacy.kelondro.data.meta.URIMetadataNode;
import net.yacy.kelondro.data.word.Word;
import net.yacy.peers.RemoteSearch;
import net.yacy.repository.Blacklist.BlacklistType;
import net.yacy.repository.LoaderDispatcher;
import net.yacy.search.Switchboard;
import net.yacy.search.query.QueryGoal;
public class TextSnippet implements Comparable<TextSnippet>, Comparator<TextSnippet> {
private static final int MAX_CACHE = 1000;
/**
* <code>\\A[^\\p{L}\\p{N}].+</code>
*/
private static final Pattern p1 =
Pattern.compile("\\A[^\\p{L}\\p{N}].+");
/**
* <code>.+[^\\p{L}\\p{N}]\\Z</code>
*/
private static final Pattern p2 =
Pattern.compile(".+[^\\p{L}\\p{N}]\\Z");
/**
* <code>\\A[\\p{L}\\p{N}]+[^\\p{L}\\p{N}].+\\Z</code>
*/
private static final Pattern p3 =
Pattern.compile("\\A[\\p{L}\\p{N}]+[^\\p{L}\\p{N}].+\\Z");
/**
* <code>[^\\p{L}\\p{N}]</code>
*/
private static final Pattern p4 =
Pattern.compile("[^\\p{L}\\p{N}]");
public static class Cache {
private final ARC<String, String> cache;
public Cache() {
this.cache = new ConcurrentARC<String, String>(MAX_CACHE, Math.min(32, 2 * Runtime.getRuntime().availableProcessors()));
}
public void put(final String wordhashes, final String urlhash, final String snippet) {
// generate key
final String key = urlhash + wordhashes;
// do nothing if snippet is known or otherwise learn new snippet
this.cache.insertIfAbsent(key, snippet);
}
public String get(final String wordhashes, final String urlhash) {
// generate key
final String key = urlhash + wordhashes;
return this.cache.get(key);
}
public boolean contains(final String wordhashes, final String urlhash) {
return this.cache.containsKey(urlhash + wordhashes);
}
}
public static final Cache snippetsCache = new Cache();
public static enum ResultClass {
SOURCE_CACHE(false),
SOURCE_FILE(false),
SOURCE_WEB(false),
SOURCE_METADATA(false),
ERROR_NO_HASH_GIVEN(true),
ERROR_SOURCE_LOADING(true),
ERROR_RESOURCE_LOADING(true),
ERROR_PARSER_FAILED(true),
ERROR_PARSER_NO_LINES(true),
ERROR_NO_MATCH(true);
private final boolean fail;
private ResultClass(final boolean fail) {
this.fail = fail;
}
public boolean fail() {
return this.fail;
}
}
private byte[] urlhash;
private String line;
private boolean isMarked;
private String error;
private ResultClass resultStatus;
public TextSnippet(
final byte[] urlhash,
final String line,
final boolean isMarked,
final ResultClass errorCode,
final String errortext) {
init(urlhash, line, isMarked, errorCode, errortext);
}
public TextSnippet(
final LoaderDispatcher loader,
final URIMetadataNode row,
final HandleSet queryhashes,
final CacheStrategy cacheStrategy,
final boolean pre,
final int snippetMaxLength,
final boolean reindexing) {
// heise = "0OQUNU3JSs05"
final DigestURI url = row.url();
if (queryhashes.isEmpty()) {
//System.out.println("found no queryhashes for URL retrieve " + url);
init(url.hash(), null, false, ResultClass.ERROR_NO_HASH_GIVEN, "no query hashes given");
return;
}
// try to get snippet from snippetCache
final ResultClass source = ResultClass.SOURCE_CACHE;
final String wordhashes = RemoteSearch.set2string(queryhashes);
final String urls = ASCII.String(url.hash());
String snippetLine = snippetsCache.get(wordhashes, urls);
if (snippetLine != null) {
// found the snippet
init(url.hash(), snippetLine, false, source, null);
return;
}
// try to get the snippet from a document at the cache (or in the web)
// this requires that the document is parsed after loading
String textline = null;
HandleSet remainingHashes = queryhashes.clone();
{ //encapsulate potential expensive sentences
Collection<StringBuilder> sentences = null;
// try to get the snippet from metadata
removeMatchingHashes(row.url().toTokens(), remainingHashes);
removeMatchingHashes(row.dc_title(), remainingHashes);
removeMatchingHashes(row.dc_creator(), remainingHashes);
removeMatchingHashes(row.dc_subject(), remainingHashes);
if (!remainingHashes.isEmpty()) {
// we did not find everything in the metadata, look further into the document itself.
// first acquire the sentences:
final String solrText = row.getText();
if (solrText != null) {
// compute sentences from solr query
final SentenceReader sr = new SentenceReader(solrText, pre);
sentences = new ArrayList<StringBuilder>();
while (sr.hasNext()) {
sentences.add(sr.next());
}
} else if (net.yacy.crawler.data.Cache.has(url.hash())) {
// get the sentences from the cache
final Request request = loader == null ? null : loader.request(url, true, reindexing);
Response response;
try {
response = loader == null || request == null ? null : loader.load(request, CacheStrategy.CACHEONLY, BlacklistType.SEARCH, ClientIdentification.yacyIntranetCrawlerAgent);
} catch (final IOException e1) {
response = null;
}
Document document = null;
if (response != null) {
try {
document = Document.mergeDocuments(response.url(), response.getMimeType(), response.parse());
sentences = document.getSentences(pre);
} catch (final Parser.Failure e) {
}
}
}
if (sentences == null) {
// not found the snippet
init(url.hash(), null, false, ResultClass.SOURCE_METADATA, null);
return;
}
if (sentences.size() > 0) {
try {
final SnippetExtractor tsr = new SnippetExtractor(sentences, remainingHashes, snippetMaxLength);
textline = tsr.getSnippet();
remainingHashes = tsr.getRemainingWords();
} catch (final UnsupportedOperationException e) {
init(url.hash(), null, false, ResultClass.ERROR_NO_MATCH, "snippet extractor failed:" + e.getMessage());
return;
}
}
}
if (remainingHashes.isEmpty()) {
// we found the snippet
if (textline == null) {
if (sentences == null) {
textline = row.dc_subject();
} else {
// use the first lines from the text as snippet
final StringBuilder s = new StringBuilder(snippetMaxLength);
for (final StringBuilder t: sentences) {
s.append(t).append(' ');
if (s.length() >= snippetMaxLength / 4 * 3) break;
}
if (s.length() > snippetMaxLength) { s.setLength(snippetMaxLength); s.trimToSize(); }
textline = s.toString();
}
}
init(url.hash(), textline.length() > 0 ? textline : this.line, false, ResultClass.SOURCE_METADATA, null);
return;
}
// try to load the resource from the cache
Response response = null;
try {
response = loader == null ? null : loader.load(loader.request(url, true, reindexing), (url.isFile() || url.isSMB()) ? CacheStrategy.NOCACHE : (cacheStrategy == null ? CacheStrategy.CACHEONLY : cacheStrategy), BlacklistType.SEARCH, ClientIdentification.yacyIntranetCrawlerAgent);
} catch (final IOException e) {
response = null;
}
if (response == null) {
// in case that we did not get any result we can still return a success when we are not allowed to go online
if (cacheStrategy == null || cacheStrategy.mustBeOffline()) {
init(url.hash(), null, false, ResultClass.ERROR_SOURCE_LOADING, "omitted network load (not allowed), no cache entry");
return;
}
// if it is still not available, report an error
init(url.hash(), null, false, ResultClass.ERROR_RESOURCE_LOADING, "error loading resource from net, no cache entry");
return;
}
if (!response.fromCache()) {
// place entry on indexing queue
Switchboard.getSwitchboard().toIndexer(response);
this.resultStatus = ResultClass.SOURCE_WEB;
}
// parse the document to get all sentenced; available for snippet computation
Document document = null;
try {
document = Document.mergeDocuments(response.url(), response.getMimeType(), response.parse());
} catch (final Parser.Failure e) {
init(url.hash(), null, false, ResultClass.ERROR_PARSER_FAILED, e.getMessage()); // cannot be parsed
return;
}
if (document == null) {
init(url.hash(), null, false, ResultClass.ERROR_PARSER_FAILED, "parser error/failed"); // cannot be parsed
return;
}
// compute sentences from parsed document
sentences = document.getSentences(pre);
document.close();
if (sentences == null) {
init(url.hash(), null, false, ResultClass.ERROR_PARSER_NO_LINES, "parser returned no sentences");
return;
}
try {
final SnippetExtractor tsr = new SnippetExtractor(sentences, remainingHashes, snippetMaxLength);
textline = tsr.getSnippet();
remainingHashes = tsr.getRemainingWords();
} catch (final UnsupportedOperationException e) {
init(url.hash(), null, false, ResultClass.ERROR_NO_MATCH, "snippet extractor failed:" + e.getMessage());
return;
}
} //encapsulate potential expensive sentences END
// compute snippet from media - attention document closed above!
//String audioline = computeMediaSnippet(document.getAudiolinks(), queryhashes);
//String videoline = computeMediaSnippet(document.getVideolinks(), queryhashes);
//String appline = computeMediaSnippet(document.getApplinks(), queryhashes);
//String hrefline = computeMediaSnippet(document.getAnchors(), queryhashes);
//String imageline = computeMediaSnippet(document.getAudiolinks(), queryhashes);
snippetLine = "";
//if (audioline != null) line += (line.isEmpty()) ? audioline : "<br />" + audioline;
//if (videoline != null) line += (line.isEmpty()) ? videoline : "<br />" + videoline;
//if (appline != null) line += (line.isEmpty()) ? appline : "<br />" + appline;
//if (hrefline != null) line += (line.isEmpty()) ? hrefline : "<br />" + hrefline;
//if (textline != null) snippetLine += (snippetLine.isEmpty()) ? textline : "<br />" + textline;
if (snippetLine == null || !remainingHashes.isEmpty()) {
init(url.hash(), null, false, ResultClass.ERROR_NO_MATCH, "no matching snippet found");
return;
}
if (snippetLine.length() > snippetMaxLength) snippetLine = snippetLine.substring(0, snippetMaxLength);
// finally store this snippet in our own cache
snippetsCache.put(wordhashes, urls, snippetLine);
// document.close();
init(url.hash(), snippetLine, false, source, null);
}
private void init(
final byte[] urlhash,
final String line,
final boolean isMarked,
final ResultClass errorCode,
final String errortext) {
this.urlhash = urlhash;
this.line = line;
this.isMarked = isMarked;
this.resultStatus = errorCode;
this.error = errortext;
}
public boolean exists() {
return this.line != null;
}
public boolean isMarked() {
return this.isMarked;
}
public String getLineRaw() {
return (this.line == null) ? "" : this.line;
}
public String getError() {
return (this.error == null) ? "" : this.error.trim();
}
public ResultClass getErrorCode() {
return this.resultStatus;
}
private static final Pattern SPLIT_PATTERN = Pattern.compile(" |-");
/**
* Marks all words in current line which have the same
* hash values as the ones contained in argument.
* @param queryHashes hashes of search words
* @return line with marked words
*/
public String getLineMarked(final QueryGoal queryGoal) {
final HandleSet queryHashes = queryGoal.getAllHashes();
if (this.line == null) {
return "";
}
if (queryHashes == null || queryHashes.isEmpty()) {
return this.line.trim();
}
if (this.line.endsWith(".")) {
this.line = this.line.substring(0, this.line.length() - 1);
}
final String[] words = SPLIT_PATTERN.split(this.line);
final Iterator<byte[]> iterator = queryHashes.iterator();
final Set<byte[]> queryHashesSet = new HashSet<byte[]>();
while (iterator.hasNext()) {
queryHashesSet.add(iterator.next());
}
for (int i = 0; i < words.length; i++) {
words[i] = getWordMarked(words[i], queryHashesSet);
}
final StringBuilder l =
new StringBuilder(this.line.length() + queryHashes.size() * 8);
for (final String word : words) {
l.append(word);
l.append(' ');
}
return l.toString().trim();
}
@Override
public int compareTo(final TextSnippet o) {
return Base64Order.enhancedCoder.compare(this.urlhash, o.urlhash);
}
@Override
public int compare(final TextSnippet o1, final TextSnippet o2) {
return o1.compareTo(o2);
}
private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
@Override
public int hashCode() {
if (this.hashCache == Integer.MIN_VALUE) {
this.hashCache = ByteArray.hashCode(this.urlhash);
}
return this.hashCache;
}
@Override
public String toString() {
return (this.line == null) ? "" : this.line;
}
/**
* Marks words with <b>-tags. <b>Beware</b>: Method
* has side effects! Certain characters in words will be
* escaped to HTML encoding. Using this method a second
* time with already escaped characters might lead to
* undesired results.
* @param word the word to mark
* @param queryHashes hashes of the words to mark
* @return the marked word if one of the hashes matches,
* else the unmarked word
* @see #getLineMarked(Set)
*/
private static String getWordMarked(
final String word, final Set<byte[]> queryHashes) {
//note to myself [MN]:
//For details on regex see "Mastering regular expressions" by J.E.F. Friedl
//especially p. 123 and p. 390/391 (in the German version of the 2nd edition)
final StringBuilder theWord = new StringBuilder(word);
final StringBuilder prefix = new StringBuilder(40);
final StringBuilder postfix = new StringBuilder(40);
int len = 0;
// cut off prefix if it contains of non-characters or non-numbers
while (p1.matcher(theWord).find()) {
prefix.append(theWord.substring(0, 1));
theWord.delete(0, 1);
}
// cut off postfix if it contains of non-characters or non-numbers
while (p2.matcher(theWord).find()) {
len = theWord.length();
postfix.insert(0, theWord.substring(len - 1, len));
theWord.delete(len - 1, len);
}
//special treatment if there is a special character in the word
if (p3.matcher(theWord).find()) {
StringBuilder out = null;
String temp = "";
for (int k = 0; k < theWord.length(); k++) {
out = new StringBuilder(80);
//is character a special character?
if (p4.matcher(theWord.substring(k, k + 1)).find()) {
if (ByteBuffer.contains(queryHashes, Word.word2hash(temp))) {
temp = "<b>" + CharacterCoding.unicode2html(temp, false) + "</b>";
}
out.append(temp);
out.append(CharacterCoding.unicode2html(theWord.substring(k, k +1), false));
temp = "";
}
//last character
else if (k == (theWord.length() - 1)) {
temp = temp + theWord.substring(k, k + 1);
if (ByteBuffer.contains(queryHashes, Word.word2hash(temp))) {
temp = "<b>" + CharacterCoding.unicode2html(temp, false) + "</b>";
}
out.append(temp);
temp = "";
}
else {
temp = temp + theWord.substring(k, k + 1);
}
}
theWord.delete(0, theWord.length());
theWord.append(out);
} else if (ByteBuffer.contains(queryHashes, Word.word2hash(theWord))) {
theWord.replace(
0,
theWord.length(),
CharacterCoding.unicode2html(theWord.toString(), false));
theWord.insert(0, "<b>");
theWord.append("</b>");
}
theWord.insert(
0,
CharacterCoding.unicode2html(prefix.toString(), false));
theWord.append(CharacterCoding.unicode2html(postfix.toString(), false));
return theWord.toString();
}
private static void removeMatchingHashes(final String sentence, final HandleSet queryhashes) {
if (queryhashes.size() == 0) return;
final Set<byte[]> m = WordTokenizer.hashSentence(sentence, null, 100).keySet();
//for (byte[] b: m) System.out.println("sentence hash: " + ASCII.String(b));
//for (byte[] b: queryhashes) System.out.println("queryhash: " + ASCII.String(b));
ArrayList<byte[]> o = new ArrayList<byte[]>(queryhashes.size());
for (final byte[] b : queryhashes) {
if (m.contains(b)) o.add(b);
}
for (final byte[] b : o) queryhashes.remove(b);
}
}