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yacy_search_server/source/de/anomic/search/TextSnippet.java

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// 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 de.anomic.search;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Iterator;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import net.yacy.document.Condenser;
import net.yacy.document.Document;
import net.yacy.document.ParserException;
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.data.word.WordReferenceVars;
import net.yacy.kelondro.index.ARC;
import net.yacy.kelondro.index.ConcurrentARC;
import net.yacy.kelondro.logging.Log;
import net.yacy.kelondro.order.Base64Order;
import net.yacy.kelondro.util.SetTools;
import net.yacy.repository.LoaderDispatcher;
import de.anomic.crawler.retrieval.Response;
import de.anomic.http.client.Cache;
import de.anomic.http.server.ResponseHeader;
import de.anomic.yacy.yacySearch;
public class TextSnippet implements Comparable<TextSnippet>, Comparator<TextSnippet> {
private static final int maxCache = 1000;
public static final int SOURCE_CACHE = 0;
public static final int SOURCE_FILE = 1;
public static final int SOURCE_WEB = 2;
public static final int SOURCE_METADATA = 3;
public static final int ERROR_NO_HASH_GIVEN = 11;
public static final int ERROR_SOURCE_LOADING = 12;
public static final int ERROR_RESOURCE_LOADING = 13;
public static final int ERROR_PARSER_FAILED = 14;
public static final int ERROR_PARSER_NO_LINES = 15;
public static final int ERROR_NO_MATCH = 16;
private static final ARC<String, String> snippetsCache = new ConcurrentARC<String, String>(maxCache, Math.max(10, Runtime.getRuntime().availableProcessors()));
private static final ARC<String, DigestURI> faviconCache = new ConcurrentARC<String, DigestURI>(maxCache, Math.max(10, Runtime.getRuntime().availableProcessors()));
private final DigestURI url;
private String line;
private final String error;
private final int errorCode;
private TreeSet<byte[]> remaingHashes;
private final DigestURI favicon;
public static boolean existsInCache(final DigestURI url, final TreeSet<byte[]> queryhashes) {
final String hashes = yacySearch.set2string(queryhashes);
return retrieveFromCache(hashes, url.hash()) != null;
}
public static void storeToCache(final String wordhashes, final String urlhash, final String snippet) {
// generate key
String key = urlhash + wordhashes;
// do nothing if snippet is known
if (snippetsCache.containsKey(key)) return;
// learn new snippet
snippetsCache.put(key, snippet);
}
public static String retrieveFromCache(final String wordhashes, final String urlhash) {
// generate key
final String key = urlhash + wordhashes;
return snippetsCache.get(key);
}
/**
* removed all word hashes that can be computed as tokens from a given sentence from a given hash set
* @param sentence
* @param queryhashes
* @return the given hash set minus the hashes from the tokenization of the given sentence
*/
public static TreeSet<byte[]> removeAppearanceHashes(final String sentence, final TreeSet<byte[]> queryhashes) {
// remove all hashes that appear in the sentence
if (sentence == null) return queryhashes;
final TreeMap<byte[], Integer> hs = Condenser.hashSentence(sentence);
final Iterator<byte[]> j = queryhashes.iterator();
byte[] hash;
Integer pos;
final TreeSet<byte[]> remaininghashes = new TreeSet<byte[]>(Base64Order.enhancedCoder);
while (j.hasNext()) {
hash = j.next();
pos = hs.get(hash);
if (pos == null) {
remaininghashes.add(hash);
}
}
return remaininghashes;
}
/**
* <code>\\A[^\\p{L}\\p{N}].+</code>
*/
private final static Pattern p1 = Pattern.compile("\\A[^\\p{L}\\p{N}].+");
/**
* <code>.+[^\\p{L}\\p{N}]\\Z</code>
*/
private final static Pattern p2 = Pattern.compile(".+[^\\p{L}\\p{N}]\\Z");
/**
* <code>\\A[\\p{L}\\p{N}]+[^\\p{L}\\p{N}].+\\Z</code>
*/
private final static Pattern p3 = Pattern.compile("\\A[\\p{L}\\p{N}]+[^\\p{L}\\p{N}].+\\Z");
/**
* <code>[^\\p{L}\\p{N}]</code>
*/
private final static Pattern p4 = Pattern.compile("[^\\p{L}\\p{N}]");
/**
* <code>(.*?)(\\&lt;b\\&gt;.+?\\&lt;/b\\&gt;)(.*)</code>
*/
private final static Pattern p01 = Pattern.compile("(.*?)(\\<b\\>.+?\\</b\\>)(.*)"); // marked words are in <b>-tags
public TextSnippet(final DigestURI url, final String line, final int errorCode, final TreeSet<byte[]> remaingHashes, final String errortext) {
this(url,line,errorCode,remaingHashes,errortext,null);
}
public TextSnippet(final DigestURI url, final String line, final int errorCode, final TreeSet<byte[]> remaingHashes, final String errortext, final DigestURI favicon) {
this.url = url;
this.line = line;
this.errorCode = errorCode;
this.error = errortext;
this.remaingHashes = remaingHashes;
this.favicon = favicon;
}
public DigestURI getUrl() {
return this.url;
}
public DigestURI getFavicon() {
return this.favicon;
}
public boolean exists() {
return line != null;
}
public int compareTo(TextSnippet o) {
return Base64Order.enhancedCoder.compare(this.url.hash().getBytes(), o.url.hash().getBytes());
}
public int compare(TextSnippet o1, TextSnippet o2) {
return o1.compareTo(o2);
}
public int hashCode() {
return this.url.hash().hashCode();
}
@Override
public String toString() {
return (line == null) ? "" : line;
}
public String getLineRaw() {
return (line == null) ? "" : line;
}
public String getError() {
return (error == null) ? "" : error.trim();
}
public int getErrorCode() {
return errorCode;
}
public TreeSet<byte[]> getRemainingHashes() {
return this.remaingHashes;
}
public String getLineMarked(final TreeSet<byte[]> queryHashes) {
if (line == null) return "";
if ((queryHashes == null) || (queryHashes.isEmpty())) return line.trim();
if (line.endsWith(".")) line = line.substring(0, line.length() - 1);
final Iterator<byte[]> i = queryHashes.iterator();
byte[] h;
final String[] w = line.split(" ");
while (i.hasNext()) {
h = i.next();
for (int j = 0; j < w.length; j++) {
final ArrayList<String> al = markedWordArrayList(w[j]); // mark special character separated words correctly if more than 1 word has to be marked
w[j] = "";
for (int k = 0; k < al.size(); k++) {
if(k % 2 == 0){ // word has not been marked
w[j] += getWordMarked(al.get(k), h);
} else { // word has been marked, do not encode again
w[j] += al.get(k);
}
}
}
}
final StringBuilder l = new StringBuilder(line.length() + queryHashes.size() * 8);
for (int j = 0; j < w.length; j++) {
l.append(w[j]);
l.append(' ');
}
return l.toString().trim();
}
/**
* mark words with &lt;b&gt;-tags
* @param word the word to mark
* @param h the hash of the word to mark
* @return the marked word if hash matches, else the unmarked word
* @see #getLineMarked(Set)
*/
private static String getWordMarked(String word, byte[] h){
//ignore punctuation marks (contrib [MN])
//note to myself:
//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)
String prefix = "";
String postfix = "";
int len = 0;
// cut off prefix if it contains of non-characters or non-numbers
while(p1.matcher(word).find()) {
prefix = prefix + word.substring(0,1);
word = word.substring(1);
}
// cut off postfix if it contains of non-characters or non-numbers
while(p2.matcher(word).find()) {
len = word.length();
postfix = word.substring(len-1,len) + postfix;
word = word.substring(0,len-1);
}
//special treatment if there is a special character in the word
if(p3.matcher(word).find()) {
String out = "";
String temp = "";
for(int k=0; k < word.length(); k++) {
//is character a special character?
if(p4.matcher(word.substring(k,k+1)).find()) {
if (new String(Word.word2hash(temp)).equals(new String(h))) temp = "<b>" + CharacterCoding.unicode2html(temp, false) + "</b>";
out = out + temp + CharacterCoding.unicode2html(word.substring(k,k+1), false);
temp = "";
}
//last character
else if(k == (word.length()-1)) {
temp = temp + word.substring(k,k+1);
if (new String(Word.word2hash(temp)).equals(new String(h))) temp = "<b>" + CharacterCoding.unicode2html(temp, false) + "</b>";
out = out + temp;
temp = "";
}
else temp = temp + word.substring(k,k+1);
}
word = out;
}
//end contrib [MN]
else if (new String(Word.word2hash(word)).equals(new String(h))) word = "<b>" + CharacterCoding.unicode2html(word, false) + "</b>";
word = CharacterCoding.unicode2html(prefix, false)
+ word
+ CharacterCoding.unicode2html(postfix, false);
return word;
}
/**
* words that already has been marked has index <code>(i % 2 == 1)</code>
* words that has not yet been marked has index <code>(i % 2 == 0)</code>
* @param string the String to be processed
* @return words that already has and has not yet been marked
* @author [DW], 08.11.2008
*/
private static ArrayList<String> markedWordArrayList(String string){
ArrayList<String> al = new java.util.ArrayList<String>(1);
Matcher m = p01.matcher(string);
while (m.find()) {
al.add(m.group(1));
al.add(m.group(2));
string = m.group(3); // the postfix
m = p01.matcher(string);
}
al.add(string);
return al;
}
@SuppressWarnings("unchecked")
public static TextSnippet retrieveTextSnippet(final URIMetadataRow.Components comp, final TreeSet<byte[]> queryhashes, final boolean fetchOnline, 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);
return new TextSnippet(url, null, ERROR_NO_HASH_GIVEN, queryhashes, "no query hashes given");
}
// try to get snippet from snippetCache
int source = SOURCE_CACHE;
final String wordhashes = yacySearch.set2string(queryhashes);
String line = retrieveFromCache(wordhashes, url.hash());
if (line != null) {
// found the snippet
return new TextSnippet(url, line, source, null, null, faviconCache.get(url.hash()));
}
/* ===========================================================================
* LOADING RESOURCE DATA
* =========================================================================== */
// if the snippet is not in the cache, we can try to get it from the htcache
byte[] resContent = null;
ResponseHeader responseHeader = null;
try {
// first try to get the snippet from metadata
String loc;
if (containsAllHashes(loc = comp.dc_title(), queryhashes)) {
// try to create the snippet from information given in the url itself
return new TextSnippet(url, loc, SOURCE_METADATA, null, null, faviconCache.get(url.hash()));
} else if (containsAllHashes(loc = comp.dc_creator(), queryhashes)) {
// try to create the snippet from information given in the creator metadata
return new TextSnippet(url, loc, SOURCE_METADATA, null, null, faviconCache.get(url.hash()));
} else if (containsAllHashes(loc = comp.dc_subject(), queryhashes)) {
// try to create the snippet from information given in the subject metadata
return new TextSnippet(url, loc, SOURCE_METADATA, null, null, faviconCache.get(url.hash()));
} else if (containsAllHashes(loc = comp.url().toNormalform(true, true).replace('-', ' '), queryhashes)) {
// try to create the snippet from information given in the subject metadata
return new TextSnippet(url, loc, SOURCE_METADATA, null, null, faviconCache.get(url.hash()));
} else {
// trying to load the resource from the cache
resContent = Cache.getContent(url);
responseHeader = Cache.getResponseHeader(url);
if (resContent != null && !fetchOnline && resContent.length > maxDocLen) {
// content may be too large to be parsed here. To be fast, we omit calculation of snippet here
return new TextSnippet(url, null, ERROR_SOURCE_LOADING, queryhashes, "resource available, but too large: " + resContent.length + " bytes");
} else if (fetchOnline) {
// if not found try to download it
// download resource using the crawler and keep resource in memory if possible
final Response entry = Switchboard.getSwitchboard().loader.load(url, true, reindexing);
// getting resource metadata (e.g. the http headers for http resources)
if (entry != null) {
// place entry on indexing queue
Switchboard.getSwitchboard().toIndexer(entry);
// read resource body (if it is there)
final byte[] resourceArray = entry.getContent();
if (resourceArray != null) {
resContent = resourceArray;
} else {
resContent = Cache.getContent(url);
}
}
// if it is still not available, report an error
if (resContent == null) return new TextSnippet(url, null, ERROR_RESOURCE_LOADING, queryhashes, "error loading resource, plasmaHTCache.Entry cache is NULL");
source = SOURCE_WEB;
} else {
return new TextSnippet(url, null, ERROR_SOURCE_LOADING, queryhashes, "no resource available");
}
}
} catch (final Exception e) {
//Log.logException(e);
return new TextSnippet(url, null, ERROR_SOURCE_LOADING, queryhashes, "error loading resource: " + e.getMessage());
}
/* ===========================================================================
* PARSING RESOURCE
* =========================================================================== */
Document document = null;
try {
document = LoaderDispatcher.parseDocument(url, resContent.length, new ByteArrayInputStream(resContent), responseHeader);
} catch (final ParserException e) {
return new TextSnippet(url, null, ERROR_PARSER_FAILED, queryhashes, e.getMessage()); // cannot be parsed
} finally {
resContent = null;
}
if (document == null) return new TextSnippet(url, null, ERROR_PARSER_FAILED, queryhashes, "parser error/failed"); // cannot be parsed
/* ===========================================================================
* COMPUTE SNIPPET
* =========================================================================== */
final DigestURI resFavicon = document.getFavicon();
if (resFavicon != null) faviconCache.put(url.hash(), resFavicon);
// we have found a parseable non-empty file: use the lines
// compute snippet from text
final Iterator<StringBuilder> sentences = document.getSentences(pre);
if (sentences == null) return new TextSnippet(url, null, ERROR_PARSER_NO_LINES, queryhashes, "parser returned no sentences",resFavicon);
final Object[] tsr = computeTextSnippet(sentences, queryhashes, snippetMaxLength);
final String textline = (tsr == null) ? null : (String) tsr[0];
final TreeSet<byte[]> remainingHashes = (tsr == null) ? queryhashes : (TreeSet<byte[]>) tsr[1];
// compute snippet from media
//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);
line = "";
//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) line += (line.length() == 0) ? textline : "<br />" + textline;
if (line == null || !remainingHashes.isEmpty()) return new TextSnippet(url, null, ERROR_NO_MATCH, remainingHashes, "no matching snippet found",resFavicon);
if (line.length() > snippetMaxLength) line = line.substring(0, snippetMaxLength);
// finally store this snippet in our own cache
storeToCache(wordhashes, url.hash(), line);
document.close();
return new TextSnippet(url, line, source, null, null, resFavicon);
}
private static boolean containsAllHashes(final String sentence, final Set<byte[]> queryhashes) {
final TreeMap<byte[], Integer> m = Condenser.hashSentence(sentence);
final Iterator<byte[]> i = queryhashes.iterator();
while (i.hasNext()) {
if (!(m.containsKey(i.next()))) return false;
}
return true;
}
@SuppressWarnings("unchecked")
private static Object[] /*{String - the snippet, Set - remaining hashes}*/
computeTextSnippet(final Iterator<StringBuilder> sentences, final TreeSet<byte[]> queryhashes, int maxLength) {
try {
if (sentences == null) return null;
if ((queryhashes == null) || (queryhashes.isEmpty())) return null;
Iterator<byte[]> j;
TreeMap<byte[], Integer> hs;
StringBuilder sentence;
final TreeMap<Integer, StringBuilder> os = new TreeMap<Integer, StringBuilder>();
int uniqCounter = 9999;
int score;
while (sentences.hasNext()) {
sentence = sentences.next();
hs = Condenser.hashSentence(sentence.toString());
j = queryhashes.iterator();
score = 0;
while (j.hasNext()) {if (hs.containsKey(j.next())) score++;}
if (score > 0) {
os.put(Integer.valueOf(1000000 * score - sentence.length() * 10000 + uniqCounter--), sentence);
}
}
String result;
TreeSet<byte[]> remaininghashes;
while (!os.isEmpty()) {
sentence = os.remove(os.lastKey()); // sentence with the biggest score
Object[] tsr = computeTextSnippet(sentence.toString(), queryhashes, maxLength);
if (tsr == null) continue;
result = (String) tsr[0];
if ((result != null) && (result.length() > 0)) {
remaininghashes = (TreeSet<byte[]>) tsr[1];
if (remaininghashes.isEmpty()) {
// we have found the snippet
return new Object[]{result, remaininghashes};
} else if (remaininghashes.size() < queryhashes.size()) {
// the result has not all words in it.
// find another sentence that represents the missing other words
// and find recursively more sentences
maxLength = maxLength - result.length();
if (maxLength < 20) maxLength = 20;
tsr = computeTextSnippet(os.values().iterator(), remaininghashes, maxLength);
if (tsr == null) return null;
final String nextSnippet = (String) tsr[0];
if (nextSnippet == null) return tsr;
return new Object[]{result + (" / " + nextSnippet), tsr[1]};
} else {
// error
//assert remaininghashes.size() < queryhashes.size() : "remaininghashes.size() = " + remaininghashes.size() + ", queryhashes.size() = " + queryhashes.size() + ", sentence = '" + sentence + "', result = '" + result + "'";
continue;
}
}
}
return null;
} catch (final IndexOutOfBoundsException e) {
Log.logSevere("computeSnippet", "error with string generation", e);
return new Object[]{null, queryhashes};
}
}
private static Object[] /*{String - the snippet, Set - remaining hashes}*/
computeTextSnippet(String sentence, final TreeSet<byte[]> queryhashes, final int maxLength) {
try {
if (sentence == null) return null;
if ((queryhashes == null) || (queryhashes.isEmpty())) return null;
byte[] hash;
// find all hashes that appear in the sentence
final TreeMap<byte[], Integer> hs = Condenser.hashSentence(sentence);
final Iterator<byte[]> j = queryhashes.iterator();
Integer pos;
int p, minpos = sentence.length(), maxpos = -1;
final TreeSet<byte[]> remainingHashes = new TreeSet<byte[]>(Base64Order.enhancedCoder);
while (j.hasNext()) {
hash = j.next();
pos = hs.get(hash);
if (pos == null) {
remainingHashes.add(hash);
} else {
p = pos.intValue();
if (p > maxpos) maxpos = p;
if (p < minpos) minpos = p;
}
}
// check result size
maxpos = maxpos + 10;
if (maxpos > sentence.length()) maxpos = sentence.length();
if (minpos < 0) minpos = 0;
// we have a result, but is it short enough?
if (maxpos - minpos + 10 > maxLength) {
// the string is too long, even if we cut at both ends
// so cut here in the middle of the string
final int lenb = sentence.length();
sentence = sentence.substring(0, (minpos + 20 > sentence.length()) ? sentence.length() : minpos + 20).trim() +
" [..] " +
sentence.substring((maxpos + 26 > sentence.length()) ? sentence.length() : maxpos + 26).trim();
maxpos = maxpos + lenb - sentence.length() + 6;
}
if (maxpos > maxLength) {
// the string is too long, even if we cut it at the end
// so cut it here at both ends at once
assert maxpos >= minpos;
final int newlen = Math.max(10, maxpos - minpos + 10);
final int around = (maxLength - newlen) / 2;
assert minpos - around < sentence.length() : "maxpos = " + maxpos + ", minpos = " + minpos + ", around = " + around + ", sentence.length() = " + sentence.length();
//assert ((maxpos + around) <= sentence.length()) && ((maxpos + around) <= sentence.length()) : "maxpos = " + maxpos + ", minpos = " + minpos + ", around = " + around + ", sentence.length() = " + sentence.length();
sentence = "[..] " + sentence.substring(minpos - around, ((maxpos + around) > sentence.length()) ? sentence.length() : (maxpos + around)).trim() + " [..]";
minpos = around;
maxpos = sentence.length() - around - 5;
}
if (sentence.length() > maxLength) {
// trim sentence, 1st step (cut at right side)
sentence = sentence.substring(0, maxpos).trim() + " [..]";
}
if (sentence.length() > maxLength) {
// trim sentence, 2nd step (cut at left side)
sentence = "[..] " + sentence.substring(minpos).trim();
}
if (sentence.length() > maxLength) {
// trim sentence, 3rd step (cut in the middle)
sentence = sentence.substring(6, 20).trim() + " [..] " + sentence.substring(sentence.length() - 26, sentence.length() - 6).trim();
}
return new Object[] {sentence, remainingHashes};
} catch (final IndexOutOfBoundsException e) {
Log.logSevere("computeSnippet", "error with string generation", e);
return null;
}
}
public static String failConsequences(Segment indexSegment, final WordReferenceVars word, final TextSnippet snippet, final String eventID) throws IOException {
// problems with snippet fetch
final String urlHash = snippet.getUrl().hash();
final String querystring = SetTools.setToString(snippet.getRemainingHashes(), ' ');
if ((snippet.getErrorCode() == ERROR_SOURCE_LOADING) ||
(snippet.getErrorCode() == ERROR_RESOURCE_LOADING) ||
(snippet.getErrorCode() == ERROR_PARSER_FAILED) ||
(snippet.getErrorCode() == ERROR_PARSER_NO_LINES)) {
Log.logInfo("TextSnippet", "error: '" + snippet.getError() + "', remove url = " + snippet.getUrl().toNormalform(false, true) + ", cause: " + snippet.getError());
indexSegment.urlMetadata().remove(urlHash);
final SearchEvent event = SearchEventCache.getEvent(eventID);
assert indexSegment != null;
assert event != null : "eventID = " + eventID;
assert event.getQuery() != null;
indexSegment.termIndex().remove(event.getQuery().queryHashes, urlHash);
event.remove(word);
}
if (snippet.getErrorCode() == ERROR_NO_MATCH) {
Log.logInfo("TextSnippet", "error: '" + snippet.getError() + "', remove words '" + querystring + "' for url = " + snippet.getUrl().toNormalform(false, true) + ", cause: " + snippet.getError());
indexSegment.termIndex().remove(snippet.getRemainingHashes(), urlHash);
SearchEventCache.getEvent(eventID).remove(word);
}
return snippet.getError();
}
}
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