| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 org.apache.lucene.analysis.en; |
| |
| /* |
| |
| Porter stemmer in Java. The original paper is in |
| |
| Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14, |
| no. 3, pp 130-137, |
| |
| See also http://www.tartarus.org/~martin/PorterStemmer/index.html |
| |
| Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below. |
| Tthe words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1] |
| is then out outside the bounds of b. |
| |
| Similarly, |
| |
| Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below. |
| 'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and |
| b[j] is then outside the bounds of b. |
| |
| Release 3. |
| |
| [ This version is derived from Release 3, modified by Brian Goetz to |
| optimize for fewer object creations. ] |
| |
| */ |
| |
| import org.apache.lucene.util.ArrayUtil; |
| |
| /** |
| * Stemmer, implementing the Porter Stemming Algorithm |
| * |
| * <p>The Stemmer class transforms a word into its root form. The input word can be provided a |
| * character at time (by calling add()), or at once by calling one of the various stem(something) |
| * methods. |
| */ |
| class PorterStemmer { |
| private char[] b; |
| private int i, /* offset into b */ j, k, k0; |
| private boolean dirty = false; |
| private static final int INITIAL_SIZE = 50; |
| |
| public PorterStemmer() { |
| 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++) if (b[o + i] != s.charAt(i)) 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, Character.BYTES)]; |
| } |
| 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; |
| } |
| |
| /* Test program for demonstrating the Stemmer. It reads a file and |
| * stems each word, writing the result to standard out. |
| * Usage: Stemmer file-name |
| public static void main(String[] args) { |
| PorterStemmer s = new PorterStemmer(); |
| |
| for (int i = 0; i < args.length; i++) { |
| try { |
| InputStream in = new FileInputStream(args[i]); |
| byte[] buffer = new byte[1024]; |
| int bufferLen, offset, ch; |
| |
| bufferLen = in.read(buffer); |
| offset = 0; |
| s.reset(); |
| |
| while(true) { |
| if (offset < bufferLen) |
| ch = buffer[offset++]; |
| else { |
| bufferLen = in.read(buffer); |
| offset = 0; |
| if (bufferLen < 0) |
| ch = -1; |
| else |
| ch = buffer[offset++]; |
| } |
| |
| if (Character.isLetter((char) ch)) { |
| s.add(Character.toLowerCase((char) ch)); |
| } |
| else { |
| s.stem(); |
| System.out.print(s.toString()); |
| s.reset(); |
| if (ch < 0) |
| break; |
| else { |
| System.out.print((char) ch); |
| } |
| } |
| } |
| |
| in.close(); |
| } |
| catch (IOException e) { |
| System.out.println("error reading " + args[i]); |
| } |
| } |
| }*/ |
| } |
