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yacy_search_server/source/net/yacy/search/snippet/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 net.yacy.search.snippet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.regex.Pattern;
import net.yacy.cora.document.encoding.ASCII;
import net.yacy.cora.document.id.DigestURL;
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.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> {
/** The maximum number of sinppet entries in the cache */
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>
* updated to <code>\\A([\\p{L}\\p{N}]+[^\\p{L}\\p{N}].+)([\\p{N}]+[.,][\\p{N}])+\\Z</code>
* to detect words with none alphanumeric chars (1) allow comma/dot surrounded by number (2)
*/
private static final Pattern p3 =
Pattern.compile("\\A([\\p{L}\\p{N}]+[^\\p{L}\\p{N}].+)([\\p{N}]+[.,][\\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();
/** Handle statistics on TextSnippet processing */
public static final TextSnippetStatistics statistics = new TextSnippetStatistics();
public static enum ResultClass {
/** Snippet provided by Solr */
SOURCE_SOLR(false),
/** Snippet retrieved from snippets cache or computed from cached document */
SOURCE_CACHE(false),
SOURCE_FILE(false),
/** Snippet computed from the original document fetched and parsed */
SOURCE_WEB(false),
/** Snippet computed by YaCy from document metadata */
SOURCE_METADATA(false),
/** Could not extract a snippet because no search term was provided */
ERROR_NO_TERM_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;
}
}
/** URL hash of this snippet */
private byte[] urlhash;
/** The raw (unmodified) line from source ( use getDescriptionLine() to get the html encoded version for display) */
private String line;
/** Set to true when query words are already marked in the input text */
private boolean isMarked;
private String error;
private ResultClass resultStatus;
public TextSnippet(
final DigestURL url,
final String line,
final boolean isMarked,
final ResultClass errorCode,
final String errortext) {
long beginTime = System.currentTimeMillis();
init(url, line, isMarked, errorCode, errortext, beginTime);
}
public TextSnippet(
final LoaderDispatcher loader,
final URIMetadataNode row,
final Set<String> queryTerms,
final HandleSet queryhashes,
final CacheStrategy cacheStrategy,
final boolean pre,
final int snippetMaxLength,
final boolean reindexing) {
long beginTime = System.currentTimeMillis();
// heise = "0OQUNU3JSs05"
final DigestURL url = row.url();
if (queryTerms.isEmpty()) {
init(url, null, false, ResultClass.ERROR_NO_TERM_GIVEN, "no query terms given", beginTime);
return;
}
// try to get snippet from snippetCache
ResultClass source = ResultClass.SOURCE_CACHE;
final String urlHash = ASCII.String(url.hash());
final String wordhashes;
if(queryhashes != null) {
wordhashes = RemoteSearch.set2string(queryhashes);
final String snippetLine = snippetsCache.get(wordhashes, urlHash);
if (snippetLine != null) {
// found the snippet
init(url, snippetLine, false, source, null, beginTime);
return;
}
} else {
wordhashes = null;
}
// 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;
Set<String> remainingTerms = new HashSet<>(queryTerms);
SentenceReader sentences = null;
List<StringBuilder> firstSentencesList = null;
// try to get the snippet from metadata
removeMatchingTerms(row.url().toTokens(), remainingTerms);
removeMatchingTerms(row.dc_title(), remainingTerms);
removeMatchingTerms(row.dc_creator(), remainingTerms);
removeMatchingTerms(row.dc_subject(), remainingTerms);
if (!remainingTerms.isEmpty()) {
// we did not find everything in the metadata, look further into the document itself.
// first acquire the sentences (from description/abstract or text):
final ArrayList<String> solrdesc = row.getDescription();
if (!solrdesc.isEmpty()) { // include description_txt (similar to solr highlighting config)
firstSentencesList = new ArrayList<>();
for (final String s : solrdesc) {
firstSentencesList.add(new StringBuilder(s));
}
}
final String solrText = row.getText();
if (solrText != null && solrText.length() > 0) { // TODO: instead of join with desc, we could check if snippet already complete and skip further computation
// compute sentences from solr query
sentences = new SentenceReader(firstSentencesList, solrText, pre);
} 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 = new SentenceReader(firstSentencesList, document.getTextString(), pre);
response = null;
document = null;
} catch (final Parser.Failure e) {
}
}
}
if (sentences == null) {
// not found the snippet
init(url, null, false, ResultClass.SOURCE_METADATA, null, beginTime);
return;
}
if (sentences.iterator().hasNext()) {
try {
final SnippetExtractor tsr = new SnippetExtractor(sentences, remainingTerms, snippetMaxLength);
textline = tsr.getSnippet();
remainingTerms = tsr.getRemainingTerms();
} catch (final UnsupportedOperationException e) {
init(url, null, false, ResultClass.ERROR_NO_MATCH, "snippet extractor failed:" + e.getMessage(), beginTime);
return;
}
}
}
if (remainingTerms.isEmpty()) {
// we found the snippet or the query is fully included in the headline or url
if (textline == null || textline.length() == 0) {
// this is the case where we don't have a snippet because all search words are included in the headline or the url
if(sentences == null) {
String solrText = row.getText();
if (solrText != null && solrText.length() > 0) {
// compute sentences from solr query
sentences = new SentenceReader(firstSentencesList, solrText, pre);
}
} else {
sentences.reset();
}
if (sentences == null || (!sentences.iterator().hasNext())) {
textline = row.dc_subject();
} else {
// use the first lines from the text after the h1 tag as snippet
// get first the h1 tag
List<String> h1 = row.h1();
if (h1 != null && h1.size() > 0) {
// find first appearance of first h1 in sentences and then take the next sentence
String h1s = h1.get(0);
if (h1s.length() > 0) {
String prevSentence = null, currentSentence;
solrsearch: for (final StringBuilder sentence: sentences) {
currentSentence = sentence.toString();
if (prevSentence != null && prevSentence.startsWith(h1s)) {
textline = currentSentence;
break solrsearch;
}
prevSentence = currentSentence;
}
}
}
if (textline == null) {
sentences.reset();
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, textline.length() > 0 ? textline : this.line, false, ResultClass.SOURCE_METADATA, null, beginTime);
return;
}
sentences = null; // we don't need this here any more
// 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, null, false, ResultClass.ERROR_SOURCE_LOADING, "omitted network load (not allowed), no cache entry", beginTime);
return;
}
// if it is still not available, report an error
init(url, null, false, ResultClass.ERROR_RESOURCE_LOADING, "error loading resource from net, no cache entry", beginTime);
return;
}
if (!response.fromCache()) {
// place entry on indexing queue
Switchboard.getSwitchboard().toIndexer(response);
source = 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, null, false, ResultClass.ERROR_PARSER_FAILED, e.getMessage(), beginTime); // cannot be parsed
return;
}
if (document == null) {
init(url, null, false, ResultClass.ERROR_PARSER_FAILED, "parser error/failed", beginTime); // cannot be parsed
return;
}
// compute sentences from parsed document
sentences = new SentenceReader(document.getTextString(), pre);
document.close();
if (!sentences.hasNext()) {
init(url, null, false, ResultClass.ERROR_PARSER_NO_LINES, "parser returned no sentences", beginTime);
return;
}
try {
final SnippetExtractor tsr = new SnippetExtractor(sentences, remainingTerms, snippetMaxLength);
textline = tsr.getSnippet();
remainingTerms = tsr.getRemainingTerms();
} catch (final UnsupportedOperationException e) {
init(url, null, false, ResultClass.ERROR_NO_MATCH, "snippet extractor failed:" + e.getMessage(), beginTime);
return;
}
sentences = null;
if (textline == null || !remainingTerms.isEmpty()) {
init(url, null, false, ResultClass.ERROR_NO_MATCH, "no matching snippet found", beginTime);
return;
}
if (textline.length() > snippetMaxLength) textline = textline.substring(0, snippetMaxLength);
// finally store this snippet in our own cache
if(wordhashes != null) {
snippetsCache.put(wordhashes, urlHash, textline);
}
init(url, textline, false, source, null, beginTime);
}
/**
* Init a snippet line for urlhash
*
* @param url hash of the url for this snippet
* @param line text to use as snippet
* @param isMarked true if query words already marked in input text
* @param errorCode
* @param errortext
* @param beginTime the time in milliseconds when TextSnippet creation started
*/
private void init(
final DigestURL url,
final String line,
final boolean isMarked,
final ResultClass errorCode,
final String errortext,
final long beginTime) {
this.urlhash = url.hash();
this.line = line;
this.isMarked = isMarked;
this.resultStatus = errorCode;
this.error = errortext;
TextSnippet.statistics.addTextSnippetStatistics(url, System.currentTimeMillis() - beginTime, this.resultStatus);
}
/**
* @return true when a snippet text is available for the document corresponding to this.urlhash
*/
public boolean exists() {
return this.line != null;
}
/**
* @return true when query words are already marked in the raw snippet text
*/
public boolean isMarked() {
return this.isMarked;
}
/**
* @return the raw snippet text line, with query words eventually already marked
*/
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 queryGoal the query goal
* @return line with marked words
*/
public String getLineMarked(final QueryGoal queryGoal) {
final HandleSet queryHashes = queryGoal.getIncludeHashes();
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();
}
private String descriptionline = null;
/**
* Snippet line formatted/encoded for display in browser
* possible html code in raw line is html encoded
* query words marked by <b>..</b>
*
* @param queryGoal
* @return html encoded snippet line
*/
public String descriptionline(QueryGoal queryGoal) {
if (descriptionline != null) return descriptionline;
if (this.isMarked) {
// html encode source, keep <b>..</b>
descriptionline = CharacterCoding.unicode2html(this.getLineRaw(), false).replaceAll("&lt;b&gt;(.+?)&lt;/b&gt;", "<b>$1</b>");
} else {
descriptionline = this.getLineMarked(queryGoal);
}
return descriptionline;
}
@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 &lt;b&gt;-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(QueryGoal)
*/
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();
}
/**
* Modify the queryTerms set : remove terms present in the given sentence.
* @param sentence a sentence potentially matching some terms of queryTerms
* @param queryTerms a set of normalized terms
*/
private static void removeMatchingTerms(final String sentence, final Set<String> queryTerms) {
if (queryTerms.size() == 0) {
return;
}
final Set<String> sentenceWords = WordTokenizer.tokenizeSentence(sentence, 100).keySet();
queryTerms.removeAll(sentenceWords);
}
}
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