// 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.ByteArrayInputStream;
import java.util.Collection;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.SortedMap;
import java.util.regex.Pattern;
import net.yacy.cora.document.ASCII;
import net.yacy.cora.document.UTF8;
import net.yacy.cora.services.federated.yacy.CacheStrategy;
import net.yacy.cora.storage.ARC;
import net.yacy.cora.storage.ConcurrentARC;
import net.yacy.document.Document;
import net.yacy.document.Parser;
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.URIMetadataRow;
import net.yacy.kelondro.data.word.Word;
import net.yacy.kelondro.index.HandleSet;
import net.yacy.kelondro.order.Base64Order;
import net.yacy.kelondro.util.ByteArray;
import net.yacy.kelondro.util.ByteBuffer;
import net.yacy.peers.RemoteSearch;
import net.yacy.repository.LoaderDispatcher;
import net.yacy.search.Switchboard;
import de.anomic.crawler.retrieval.Request;
import de.anomic.crawler.retrieval.Response;
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.max(32, 4 * 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 String error;
private ResultClass resultStatus;
public TextSnippet(
final byte[] urlhash,
final String line,
final ResultClass errorCode,
final String errortext) {
init(urlhash, line, errorCode, errortext);
}
public TextSnippet(
final LoaderDispatcher loader,
final String solrText,
final URIMetadataRow.Components comp,
final HandleSet queryhashes,
final CacheStrategy cacheStrategy,
final boolean pre,
final int snippetMaxLength,
final int maxDocLen,
final boolean reindexing) {
// heise = "0OQUNU3JSs05"
final DigestURI url = comp.url();
if (queryhashes.isEmpty()) {
//System.out.println("found no queryhashes for URL retrieve " + url);
init(url.hash(), null, 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, 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;
{ //encapsulate potential expensive sentences
Collection<StringBuilder> sentences = null;
// try the solr text first
if (solrText != null) {
// compute sentences from solr query
sentences = Document.getSentences(pre, new ByteArrayInputStream(UTF8.getBytes(solrText)));
}
// if then no sentences are found, we fail-over to get the content from the re-loaded document
if (sentences == null) {
final Document document = loadDocument(loader, comp, queryhashes, cacheStrategy, url, reindexing, source);
if (document == null) {
return;
}
// compute sentences from parsed document
sentences = document.getSentences(pre);
document.close();
if (sentences == null) {
init(url.hash(), null, ResultClass.ERROR_PARSER_NO_LINES, "parser returned no sentences");
return;
}
}
if (this.resultStatus == ResultClass.SOURCE_METADATA) {
// if we already know that there is a match then 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(); }
init(url.hash(), s.length() > 0 ? s.toString() : this.line, ResultClass.SOURCE_METADATA, null);
return;
}
try {
final SnippetExtractor tsr = new SnippetExtractor(sentences, queryhashes, snippetMaxLength);
textline = tsr.getSnippet();
remainingHashes = tsr.getRemainingWords();
} catch (final UnsupportedOperationException e) {
init(url.hash(), null, ResultClass.ERROR_NO_MATCH, "no matching snippet found");
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.length() == 0) ? audioline : "<br />" + audioline;
//if (videoline != null) line += (line.length() == 0) ? videoline : "<br />" + videoline;
//if (appline != null) line += (line.length() == 0) ? appline : "<br />" + appline;
//if (hrefline != null) line += (line.length() == 0) ? hrefline : "<br />" + hrefline;
if (textline != null) snippetLine += (snippetLine.length() == 0) ? textline : "<br />" + textline;
if (snippetLine == null || !remainingHashes.isEmpty()) {
init(url.hash(), null, 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, source, null);
}
private Document loadDocument(
final LoaderDispatcher loader,
final URIMetadataRow.Components comp,
final HandleSet queryhashes,
final CacheStrategy cacheStrategy,
final DigestURI url,
final boolean reindexing,
ResultClass source) {
/* ===========================================================================
* LOAD RESOURCE DATA
* =========================================================================== */
// if the snippet is not in the cache, we can try to get it from the htcache
Response response = null;
try {
// first try to get the snippet from metadata
String loc;
final Request request = loader.request(url, true, reindexing);
final boolean inCache = de.anomic.http.client.Cache.has(comp.url());
final boolean noCacheUsage = url.isFile() || url.isSMB() || cacheStrategy == null;
if (containsAllHashes(loc = comp.dc_title(), queryhashes) ||
containsAllHashes(loc = comp.dc_creator(), queryhashes) ||
containsAllHashes(loc = comp.dc_subject(), queryhashes) ||
containsAllHashes(loc = comp.url().toNormalform(true, true).replace('-', ' '), queryhashes)) {
// try to create the snippet from information given in the url
if (inCache) response = loader == null ? null : loader.load(request, CacheStrategy.CACHEONLY, true);
Document document = null;
if (response != null) {
try {
document = Document.mergeDocuments(response.url(), response.getMimeType(), response.parse());
} catch (final Parser.Failure e) {
}
}
init(url.hash(), loc, ResultClass.SOURCE_METADATA, null);
return document;
} else {
// try to load the resource from the cache
response = loader == null ? null : loader.load(request, noCacheUsage ? CacheStrategy.NOCACHE : cacheStrategy, true);
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, ResultClass.ERROR_SOURCE_LOADING, "omitted network load (not allowed), no cache entry");
return null;
}
// if it is still not available, report an error
init(url.hash(), null, ResultClass.ERROR_RESOURCE_LOADING, "error loading resource from net, no cache entry");
return null;
} else {
// place entry on indexing queue
Switchboard.getSwitchboard().toIndexer(response);
source = ResultClass.SOURCE_WEB;
}
}
} catch (final Exception e) {
//Log.logException(e);
init(url.hash(), null, ResultClass.ERROR_SOURCE_LOADING, "error loading resource: " + e.getMessage());
return null;
}
/* ===========================================================================
* PARSE RESOURCE
* =========================================================================== */
Document document = null;
try {
document = Document.mergeDocuments(response.url(), response.getMimeType(), response.parse());
} catch (final Parser.Failure e) {
init(url.hash(), null, ResultClass.ERROR_PARSER_FAILED, e.getMessage()); // cannot be parsed
return null;
}
if (document == null) {
init(url.hash(), null, ResultClass.ERROR_PARSER_FAILED, "parser error/failed"); // cannot be parsed
}
return document;
}
private void init(
final byte[] urlhash,
final String line,
final ResultClass errorCode,
final String errortext) {
this.urlhash = urlhash;
this.line = line;
this.resultStatus = errorCode;
this.error = errortext;
}
public boolean exists() {
return this.line != null;
}
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 HandleSet queryHashes) {
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();
}
public int compareTo(final TextSnippet o) {
return Base64Order.enhancedCoder.compare(this.urlhash, o.urlhash);
}
public int compare(final TextSnippet o1, final TextSnippet o2) {
return o1.compareTo(o2);
}
@Override
public int hashCode() {
return ByteArray.hashCode(this.urlhash);
}
@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 boolean containsAllHashes(
final String sentence, final HandleSet queryhashes) {
final SortedMap<byte[], Integer> m =
WordTokenizer.hashSentence(sentence, null);
for (final byte[] b : queryhashes) {
if (!(m.containsKey(b))) {
return false;
}
}
return true;
}
}