/**
* Copyright 2013-2015 Pierre Merienne
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.github.pmerienne.trident.ml.preprocessing;
import static org.apache.lucene.util.RamUsageEstimator.NUM_BYTES_CHAR;
import java.io.IOException;
import java.io.Reader;
import java.io.Serializable;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.CharArraySet;
import org.apache.lucene.analysis.KeywordMarkerFilter;
import org.apache.lucene.analysis.LowerCaseFilter;
import org.apache.lucene.analysis.PorterStemFilter;
import org.apache.lucene.analysis.StopFilter;
import org.apache.lucene.analysis.StopwordAnalyzerBase;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.en.EnglishAnalyzer;
import org.apache.lucene.analysis.en.EnglishPossessiveFilter;
import org.apache.lucene.analysis.shingle.ShingleFilter;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.analysis.standard.StandardFilter;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.KeywordAttribute;
import org.apache.lucene.util.ArrayUtil;
import org.apache.lucene.util.Version;
import org.tartarus.snowball.ext.PorterStemmer;
/**
* Abstraction of lucene tokenizer.
*
* This file contains custom re-implementation of {@link EnglishAnalyzer},
* {@link PorterStemFilter} and {@link PorterStemmer} to fix
*
* <a href="https://issues.apache.org/jira/browse/LUCENE-3335">Issue
* LUCENE-3335</a>
*
* causing sigsegv!
*
* @author pmerienne
*
*/
public class EnglishTokenizer implements Serializable, TextTokenizer {
private static final long serialVersionUID = -4307517944955017402L;
private static final Log LOGGER = LogFactory.getLog(EnglishTokenizer.class);
private final transient static Version LUCENE_VERSION = Version.LUCENE_36;
protected List<String> stopWords = null;
protected Set<String> stemExclusionsSet = new HashSet<String>();
private boolean nGram = false;
private int minNGram = 2;
private int maxNGram = 2;
public EnglishTokenizer() {
}
public EnglishTokenizer(int minNGram, int maxNGram) {
this.nGram = true;
this.minNGram = minNGram;
this.maxNGram = maxNGram;
}
public EnglishTokenizer(List<String> stopWords) {
this.stopWords = stopWords;
}
public EnglishTokenizer(List<String> stopWords, Set<String> stemExclusionsSet) {
this.stopWords = stopWords;
this.stemExclusionsSet = stemExclusionsSet;
}
public List<String> tokenize(String text) {
List<String> words = new ArrayList<String>();
if (text != null && !text.isEmpty()) {
TokenStream tokenStream = this.createTokenStream(text);
CharTermAttribute charTermAttribute = tokenStream.addAttribute(CharTermAttribute.class);
try {
while (tokenStream.incrementToken()) {
String term = charTermAttribute.toString();
words.add(term);
}
} catch (IOException ioe) {
LOGGER.error("Unable to analyze text. Cause : " + ioe.getMessage(), ioe);
} finally {
try {
tokenStream.end();
tokenStream.close();
} catch (IOException e) {
// Can't do nothing!!
LOGGER.error("Unable to close token stream : " + e.getMessage());
}
}
}
return words;
}
protected TokenStream createTokenStream(String text) {
Set<?> luceneStopWords = this.stopWords == null ? EnglishAnalyzer.getDefaultStopSet() : StopFilter.makeStopSet(LUCENE_VERSION, stopWords);
Analyzer analyzer = new EnglishSpecialAnalyzer(LUCENE_VERSION, luceneStopWords, this.stemExclusionsSet);
TokenStream tokenStream = analyzer.tokenStream(null, new StringReader(text));
if (this.nGram) {
tokenStream = new ShingleFilter(tokenStream, this.minNGram, this.maxNGram);
}
return tokenStream;
}
public void setNGram(int minNGram, int maxNGram) {
this.nGram = true;
this.minNGram = minNGram;
this.maxNGram = maxNGram;
}
public boolean isnGram() {
return nGram;
}
public void setnGram(boolean nGram) {
this.nGram = nGram;
}
public int getMinNGram() {
return minNGram;
}
public void setMinNGram(int minNGram) {
this.minNGram = minNGram;
}
public int getMaxNGram() {
return maxNGram;
}
public void setMaxNGram(int maxNGram) {
this.maxNGram = maxNGram;
}
public List<String> getStopWords() {
return stopWords;
}
public void setStopWords(List<String> stopWords) {
this.stopWords = stopWords;
}
public void setStemExclusionsSet(Set<String> stemExclusionsSet) {
this.stemExclusionsSet = stemExclusionsSet;
}
public Set<String> getStemExclusionsSet() {
return stemExclusionsSet;
}
@SuppressWarnings("unused")
private static class EnglishSpecialAnalyzer extends StopwordAnalyzerBase {
private final Set<?> stemExclusionSet;
/**
* Returns an unmodifiable instance of the default stop words set.
*
* @return default stop words set.
*/
public static Set<?> getDefaultStopSet() {
return DefaultSetHolder.DEFAULT_STOP_SET;
}
/**
* Atomically loads the DEFAULT_STOP_SET in a lazy fashion once the
* outer class accesses the static final set the first time.;
*/
private static class DefaultSetHolder {
static final Set<?> DEFAULT_STOP_SET = StandardAnalyzer.STOP_WORDS_SET;
}
/**
* Builds an analyzer with the default stop words:
* {@link #getDefaultStopSet}.
*/
public EnglishSpecialAnalyzer(Version matchVersion) {
this(matchVersion, DefaultSetHolder.DEFAULT_STOP_SET);
}
/**
* Builds an analyzer with the given stop words.
*
* @param matchVersion
* lucene compatibility version
* @param stopwords
* a stopword set
*/
public EnglishSpecialAnalyzer(Version matchVersion, Set<?> stopwords) {
this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
}
/**
* Builds an analyzer with the given stop words. If a non-empty stem
* exclusion set is provided this analyzer will add a
* {@link KeywordMarkerFilter} before stemming.
*
* @param matchVersion
* lucene compatibility version
* @param stopwords
* a stopword set
* @param stemExclusionSet
* a set of terms not to be stemmed
*/
public EnglishSpecialAnalyzer(Version matchVersion, Set<?> stopwords, Set<?> stemExclusionSet) {
super(matchVersion, stopwords);
this.stemExclusionSet = CharArraySet.unmodifiableSet(CharArraySet.copy(matchVersion, stemExclusionSet));
}
/**
* Creates a
* {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
* which tokenizes all the text in the provided {@link Reader}.
*
* @return A
* {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
* built from an {@link StandardTokenizer} filtered with
* {@link StandardFilter}, {@link LowerCaseFilter},
* {@link StopFilter} , {@link KeywordMarkerFilter} if a stem
* exclusion set is provided and {@link PorterStemFilter}.
*/
@SuppressWarnings("deprecation")
@Override
protected TokenStreamComponents createComponents(String fieldName, Reader reader) {
final Tokenizer source = new StandardTokenizer(matchVersion, reader);
TokenStream result = new StandardFilter(matchVersion, source);
// prior to this we get the classic behavior, standardfilter does it
// for us.
if (matchVersion.onOrAfter(Version.LUCENE_31))
result = new EnglishPossessiveFilter(result);
result = new LowerCaseFilter(matchVersion, result);
result = new StopFilter(matchVersion, result, stopwords);
if (!stemExclusionSet.isEmpty())
result = new KeywordMarkerFilter(result, stemExclusionSet);
result = new PorterSpecialStemFilter(result);
return new TokenStreamComponents(source, result);
}
}
private static class PorterSpecialStemFilter extends TokenFilter {
private final PorterSpecialStemmer stemmer = new PorterSpecialStemmer();
private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
private final KeywordAttribute keywordAttr = addAttribute(KeywordAttribute.class);
public PorterSpecialStemFilter(TokenStream in) {
super(in);
}
@Override
public final boolean incrementToken() throws IOException {
if (!input.incrementToken())
return false;
if ((!keywordAttr.isKeyword()) && stemmer.stem(termAtt.buffer(), 0, termAtt.length()))
termAtt.copyBuffer(stemmer.getResultBuffer(), 0, stemmer.getResultLength());
return true;
}
}
@SuppressWarnings("unused")
private static class PorterSpecialStemmer {
private char[] b;
private int i, /* offset into b */
j, k, k0;
private boolean dirty = false;
private static final int INITIAL_SIZE = 50;
public PorterSpecialStemmer() {
b = new char[INITIAL_SIZE];
i = 0;
}
/**
* reset() resets the stemmer so it can stem another word. If you invoke
* the stemmer by calling add(char) and then stem(), you must call
* reset() before starting another word.
*/
public void reset() {
i = 0;
dirty = false;
}
/**
* Add a character to the word being stemmed. When you are finished
* adding characters, you can call stem(void) to process the word.
*/
public void add(char ch) {
if (b.length <= i) {
b = ArrayUtil.grow(b, i + 1);
}
b[i++] = ch;
}
/**
* After a word has been stemmed, it can be retrieved by toString(), or
* a reference to the internal buffer can be retrieved by
* getResultBuffer and getResultLength (which is generally more
* efficient.)
*/
@Override
public String toString() {
return new String(b, 0, i);
}
/**
* Returns the length of the word resulting from the stemming process.
*/
public int getResultLength() {
return i;
}
/**
* Returns a reference to a character buffer containing the results of
* the stemming process. You also need to consult getResultLength() to
* determine the length of the result.
*/
public char[] getResultBuffer() {
return b;
}
/* cons(i) is true <=> b[i] is a consonant. */
private final boolean cons(int i) {
switch (b[i]) {
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
return false;
case 'y':
return (i == k0) ? true : !cons(i - 1);
default:
return true;
}
}
/*
* m() measures the number of consonant sequences between k0 and j. if c
* is a consonant sequence and v a vowel sequence, and <..> indicates
* arbitrary presence,
*
* <c><v> gives 0 <c>vc<v> gives 1 <c>vcvc<v> gives 2 <c>vcvcvc<v> gives
* 3 ....
*/
private final int m() {
int n = 0;
int i = k0;
while (true) {
if (i > j)
return n;
if (!cons(i))
break;
i++;
}
i++;
while (true) {
while (true) {
if (i > j)
return n;
if (cons(i))
break;
i++;
}
i++;
n++;
while (true) {
if (i > j)
return n;
if (!cons(i))
break;
i++;
}
i++;
}
}
/* vowelinstem() is true <=> k0,...j contains a vowel */
private final boolean vowelinstem() {
int i;
for (i = k0; i <= j; i++)
if (!cons(i))
return true;
return false;
}
/* doublec(j) is true <=> j,(j-1) contain a double consonant. */
private final boolean doublec(int j) {
if (j < k0 + 1)
return false;
if (b[j] != b[j - 1])
return false;
return cons(j);
}
/*
* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel -
* consonant and also if the second c is not w,x or y. this is used when
* trying to restore an e at the end of a short word. e.g.
*
* cav(e), lov(e), hop(e), crim(e), but snow, box, tray.
*/
private final boolean cvc(int i) {
if (i < k0 + 2 || !cons(i) || cons(i - 1) || !cons(i - 2))
return false;
else {
int ch = b[i];
if (ch == 'w' || ch == 'x' || ch == 'y')
return false;
}
return true;
}
private final boolean ends(String s) {
int l = s.length();
int o = k - l + 1;
if (o < k0)
return false;
for (int i = 0; i < l; i++) {
final char ch = s.charAt(i);
/*
* LUCENE-3335: ch == 0 check added to prevent hotspot crash: no
* endings that are stripped contain this.
*/
if (ch == 0 || b[o + i] != ch)
return false;
}
j = k - l;
return true;
}
/*
* setto(s) sets (j+1),...k to the characters in the string s,
* readjusting k.
*/
void setto(String s) {
int l = s.length();
int o = j + 1;
for (int i = 0; i < l; i++)
b[o + i] = s.charAt(i);
k = j + l;
dirty = true;
}
/* r(s) is used further down. */
void r(String s) {
if (m() > 0)
setto(s);
}
/*
* step1() gets rid of plurals and -ed or -ing. e.g.
*
* caresses -> caress ponies -> poni ties -> ti caress -> caress cats ->
* cat
*
* feed -> feed agreed -> agree disabled -> disable
*
* matting -> mat mating -> mate meeting -> meet milling -> mill messing
* -> mess
*
* meetings -> meet
*/
private final void step1() {
if (b[k] == 's') {
if (ends("sses"))
k -= 2;
else if (ends("ies"))
setto("i");
else if (b[k - 1] != 's')
k--;
}
if (ends("eed")) {
if (m() > 0)
k--;
} else if ((ends("ed") || ends("ing")) && vowelinstem()) {
k = j;
if (ends("at"))
setto("ate");
else if (ends("bl"))
setto("ble");
else if (ends("iz"))
setto("ize");
else if (doublec(k)) {
int ch = b[k--];
if (ch == 'l' || ch == 's' || ch == 'z')
k++;
} else if (m() == 1 && cvc(k))
setto("e");
}
}
/*
* step2() turns terminal y to i when there is another vowel in the
* stem.
*/
private final void step2() {
if (ends("y") && vowelinstem()) {
b[k] = 'i';
dirty = true;
}
}
/*
* step3() maps double suffices to single ones. so -ization ( = -ize
* plus -ation) maps to -ize etc. note that the string before the suffix
* must give m() > 0.
*/
private final void step3() {
if (k == k0)
return; /* For Bug 1 */
switch (b[k - 1]) {
case 'a':
if (ends("ational")) {
r("ate");
break;
}
if (ends("tional")) {
r("tion");
break;
}
break;
case 'c':
if (ends("enci")) {
r("ence");
break;
}
if (ends("anci")) {
r("ance");
break;
}
break;
case 'e':
if (ends("izer")) {
r("ize");
break;
}
break;
case 'l':
if (ends("bli")) {
r("ble");
break;
}
if (ends("alli")) {
r("al");
break;
}
if (ends("entli")) {
r("ent");
break;
}
if (ends("eli")) {
r("e");
break;
}
if (ends("ousli")) {
r("ous");
break;
}
break;
case 'o':
if (ends("ization")) {
r("ize");
break;
}
if (ends("ation")) {
r("ate");
break;
}
if (ends("ator")) {
r("ate");
break;
}
break;
case 's':
if (ends("alism")) {
r("al");
break;
}
if (ends("iveness")) {
r("ive");
break;
}
if (ends("fulness")) {
r("ful");
break;
}
if (ends("ousness")) {
r("ous");
break;
}
break;
case 't':
if (ends("aliti")) {
r("al");
break;
}
if (ends("iviti")) {
r("ive");
break;
}
if (ends("biliti")) {
r("ble");
break;
}
break;
case 'g':
if (ends("logi")) {
r("log");
break;
}
}
}
/* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */
private final void step4() {
switch (b[k]) {
case 'e':
if (ends("icate")) {
r("ic");
break;
}
if (ends("ative")) {
r("");
break;
}
if (ends("alize")) {
r("al");
break;
}
break;
case 'i':
if (ends("iciti")) {
r("ic");
break;
}
break;
case 'l':
if (ends("ical")) {
r("ic");
break;
}
if (ends("ful")) {
r("");
break;
}
break;
case 's':
if (ends("ness")) {
r("");
break;
}
break;
}
}
/* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */
private final void step5() {
if (k == k0)
return; /* for Bug 1 */
switch (b[k - 1]) {
case 'a':
if (ends("al"))
break;
return;
case 'c':
if (ends("ance"))
break;
if (ends("ence"))
break;
return;
case 'e':
if (ends("er"))
break;
return;
case 'i':
if (ends("ic"))
break;
return;
case 'l':
if (ends("able"))
break;
if (ends("ible"))
break;
return;
case 'n':
if (ends("ant"))
break;
if (ends("ement"))
break;
if (ends("ment"))
break;
/* element etc. not stripped before the m */
if (ends("ent"))
break;
return;
case 'o':
if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't'))
break;
/* j >= 0 fixes Bug 2 */
if (ends("ou"))
break;
return;
/* takes care of -ous */
case 's':
if (ends("ism"))
break;
return;
case 't':
if (ends("ate"))
break;
if (ends("iti"))
break;
return;
case 'u':
if (ends("ous"))
break;
return;
case 'v':
if (ends("ive"))
break;
return;
case 'z':
if (ends("ize"))
break;
return;
default:
return;
}
if (m() > 1)
k = j;
}
/* step6() removes a final -e if m() > 1. */
private final void step6() {
j = k;
if (b[k] == 'e') {
int a = m();
if (a > 1 || a == 1 && !cvc(k - 1))
k--;
}
if (b[k] == 'l' && doublec(k) && m() > 1)
k--;
}
/**
* Stem a word provided as a String. Returns the result as a String.
*/
public String stem(String s) {
if (stem(s.toCharArray(), s.length()))
return toString();
else
return s;
}
/**
* Stem a word contained in a char[]. Returns true if the stemming
* process resulted in a word different from the input. You can retrieve
* the result with getResultLength()/getResultBuffer() or toString().
*/
public boolean stem(char[] word) {
return stem(word, word.length);
}
/**
* Stem a word contained in a portion of a char[] array. Returns true if
* the stemming process resulted in a word different from the input. You
* can retrieve the result with getResultLength()/getResultBuffer() or
* toString().
*/
public boolean stem(char[] wordBuffer, int offset, int wordLen) {
reset();
if (b.length < wordLen) {
b = new char[ArrayUtil.oversize(wordLen, NUM_BYTES_CHAR)];
}
System.arraycopy(wordBuffer, offset, b, 0, wordLen);
i = wordLen;
return stem(0);
}
/**
* Stem a word contained in a leading portion of a char[] array. Returns
* true if the stemming process resulted in a word different from the
* input. You can retrieve the result with
* getResultLength()/getResultBuffer() or toString().
*/
public boolean stem(char[] word, int wordLen) {
return stem(word, 0, wordLen);
}
/**
* Stem the word placed into the Stemmer buffer through calls to add().
* Returns true if the stemming process resulted in a word different
* from the input. You can retrieve the result with
* getResultLength()/getResultBuffer() or toString().
*/
public boolean stem() {
return stem(0);
}
public boolean stem(int i0) {
k = i - 1;
k0 = i0;
if (k > k0 + 1) {
step1();
step2();
step3();
step4();
step5();
step6();
}
// Also, a word is considered dirty if we lopped off letters
// Thanks to Ifigenia Vairelles for pointing this out.
if (i != k + 1)
dirty = true;
i = k + 1;
return dirty;
}
}
}