/*
* Copyright 2000-2009 JetBrains s.r.o.
*
* 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.intellij.ide.ui.search;
import org.jetbrains.annotations.Nullable;
@SuppressWarnings({"HardCodedStringLiteral"})
public class PorterStemmerUtil {
private PorterStemmerUtil() {
}
@Nullable
public static String stem(String str) {
// check for zero length
final int strLen = str.length();
if (strLen > 0) {
int lastNonLetter = -1;
for (int i = 0; i < strLen; ++i) {
char c = str.charAt(i);
if (Character.isDigit(c) || c == '-' || c == '_') {
lastNonLetter = i;
}
else if (!Character.isLetter(c)) {
return null;
}
}
++lastNonLetter;
if (lastNonLetter > 0 && lastNonLetter < strLen) {
return str.substring(0, lastNonLetter) + stemString(str.substring(lastNonLetter));
}
return stemString(str);
}
return null;
}
private static String stemString(String str) {
str = step1a(str);
str = step1b(str);
str = step1c(str);
str = step2(str);
str = step3(str);
str = step4(str);
str = step5a(str);
str = step5b(str);
return str;
}
private static String step1a(String str) {
// SSES -> SS
if (str.endsWith("sses")) {
return str.substring(0, str.length() - 2);
// IES -> I
}
else if (str.endsWith("ies")) {
return str.substring(0, str.length() - 2);
// SS -> S
}
else if (str.endsWith("ss")) {
return str;
// S ->
}
else if (str.endsWith("s")) {
return str.substring(0, str.length() - 1);
}
else {
return str;
}
}
private static String step1b(String str) {
// (m > 0) EED -> EE
if (str.endsWith("eed")) {
if (stringMeasure(str.substring(0, str.length() - 3)) > 0) {
return str.substring(0, str.length() - 1);
}
else {
return str;
}
// (*v*) ED ->
}
else if ((str.endsWith("ed")) && (containsVowel(str.substring(0, str.length() - 2)))) {
return step1b2(str.substring(0, str.length() - 2));
// (*v*) ING ->
}
else if ((str.endsWith("ing")) && (containsVowel(str.substring(0, str.length() - 3)))) {
return step1b2(str.substring(0, str.length() - 3));
}
return str;
}
private static String step1b2(String str) {
// AT -> ATE
if (str.endsWith("at") || str.endsWith("bl") || str.endsWith("iz")) {
return str + "e";
}
else if ((endsWithDoubleConsonent(str)) && (!(str.endsWith("l") || str.endsWith("s") || str.endsWith("z")))) {
return str.substring(0, str.length() - 1);
}
else if ((stringMeasure(str) == 1) && (endsWithCVC(str))) {
return str + "e";
}
else {
return str;
}
}
private static String step1c(String str) {
// (*v*) Y -> I
if (str.endsWith("y")) {
if (containsVowel(str.substring(0, str.length() - 1))) return str.substring(0, str.length() - 1) + "i";
}
return str;
}
private static String step2(String str) {
// (m > 0) ATIONAL -> ATE
if ((str.endsWith("ational")) && (stringMeasure(str.substring(0, str.length() - 5)) > 0)) {
return str.substring(0, str.length() - 5) + "e";
// (m > 0) TIONAL -> TION
}
else if ((str.endsWith("tional")) && (stringMeasure(str.substring(0, str.length() - 2)) > 0)) {
return str.substring(0, str.length() - 2);
// (m > 0) ENCI -> ENCE
}
else if ((str.endsWith("enci")) && (stringMeasure(str.substring(0, str.length() - 2)) > 0)) {
return str.substring(0, str.length() - 2);
// (m > 0) ANCI -> ANCE
}
else if ((str.endsWith("anci")) && (stringMeasure(str.substring(0, str.length() - 1)) > 0)) {
return str.substring(0, str.length() - 1) + "e";
// (m > 0) IZER -> IZE
}
else if ((str.endsWith("izer")) && (stringMeasure(str.substring(0, str.length() - 1)) > 0)) {
return str.substring(0, str.length() - 1);
// (m > 0) ABLI -> ABLE
}
else if ((str.endsWith("abli")) && (stringMeasure(str.substring(0, str.length() - 1)) > 0)) {
return str.substring(0, str.length() - 1) + "e";
// (m > 0) ENTLI -> ENT
}
else if ((str.endsWith("alli")) && (stringMeasure(str.substring(0, str.length() - 2)) > 0)) {
return str.substring(0, str.length() - 2);
// (m > 0) ELI -> E
}
else if ((str.endsWith("entli")) && (stringMeasure(str.substring(0, str.length() - 2)) > 0)) {
return str.substring(0, str.length() - 2);
// (m > 0) OUSLI -> OUS
}
else if ((str.endsWith("eli")) && (stringMeasure(str.substring(0, str.length() - 2)) > 0)) {
return str.substring(0, str.length() - 2);
// (m > 0) IZATION -> IZE
}
else if ((str.endsWith("ousli")) && (stringMeasure(str.substring(0, str.length() - 2)) > 0)) {
return str.substring(0, str.length() - 2);
// (m > 0) IZATION -> IZE
}
else if ((str.endsWith("ization")) && (stringMeasure(str.substring(0, str.length() - 5)) > 0)) {
return str.substring(0, str.length() - 5) + "e";
// (m > 0) ATION -> ATE
}
else if ((str.endsWith("ation")) && (stringMeasure(str.substring(0, str.length() - 3)) > 0)) {
return str.substring(0, str.length() - 3) + "e";
// (m > 0) ATOR -> ATE
}
else if ((str.endsWith("ator")) && (stringMeasure(str.substring(0, str.length() - 2)) > 0)) {
return str.substring(0, str.length() - 2) + "e";
// (m > 0) ALISM -> AL
}
else if ((str.endsWith("alism")) && (stringMeasure(str.substring(0, str.length() - 3)) > 0)) {
return str.substring(0, str.length() - 3);
// (m > 0) IVENESS -> IVE
}
else if ((str.endsWith("iveness")) && (stringMeasure(str.substring(0, str.length() - 4)) > 0)) {
return str.substring(0, str.length() - 4);
// (m > 0) FULNESS -> FUL
}
else if ((str.endsWith("fulness")) && (stringMeasure(str.substring(0, str.length() - 4)) > 0)) {
return str.substring(0, str.length() - 4);
// (m > 0) OUSNESS -> OUS
}
else if ((str.endsWith("ousness")) && (stringMeasure(str.substring(0, str.length() - 4)) > 0)) {
return str.substring(0, str.length() - 4);
// (m > 0) ALITII -> AL
}
else if ((str.endsWith("aliti")) && (stringMeasure(str.substring(0, str.length() - 3)) > 0)) {
return str.substring(0, str.length() - 3);
// (m > 0) IVITI -> IVE
}
else if ((str.endsWith("iviti")) && (stringMeasure(str.substring(0, str.length() - 3)) > 0)) {
return str.substring(0, str.length() - 3) + "e";
// (m > 0) BILITI -> BLE
}
else if ((str.endsWith("biliti")) && (stringMeasure(str.substring(0, str.length() - 5)) > 0)) {
return str.substring(0, str.length() - 5) + "le";
}
return str;
}
private static String step3(String str) {
// (m > 0) ICATE -> IC
if ((str.endsWith("icate")) && (stringMeasure(str.substring(0, str.length() - 3)) > 0)) {
return str.substring(0, str.length() - 3);
// (m > 0) ATIVE ->
}
else if ((str.endsWith("ative")) && (stringMeasure(str.substring(0, str.length() - 5)) > 0)) {
return str.substring(0, str.length() - 5);
// (m > 0) ALIZE -> AL
}
else if ((str.endsWith("alize")) && (stringMeasure(str.substring(0, str.length() - 3)) > 0)) {
return str.substring(0, str.length() - 3);
// (m > 0) ICITI -> IC
}
else if ((str.endsWith("iciti")) && (stringMeasure(str.substring(0, str.length() - 3)) > 0)) {
return str.substring(0, str.length() - 3);
// (m > 0) ICAL -> IC
}
else if ((str.endsWith("ical")) && (stringMeasure(str.substring(0, str.length() - 2)) > 0)) {
return str.substring(0, str.length() - 2);
// (m > 0) FUL ->
}
else if ((str.endsWith("ful")) && (stringMeasure(str.substring(0, str.length() - 3)) > 0)) {
return str.substring(0, str.length() - 3);
// (m > 0) NESS ->
}
else if ((str.endsWith("ness")) && (stringMeasure(str.substring(0, str.length() - 4)) > 0)) {
return str.substring(0, str.length() - 4);
}
return str;
}
private static String step4(String str) {
if ((str.endsWith("al")) && (stringMeasure(str.substring(0, str.length() - 2)) > 1)) {
return str.substring(0, str.length() - 2);
// (m > 1) ANCE ->
}
else if ((str.endsWith("ance")) && (stringMeasure(str.substring(0, str.length() - 4)) > 1)) {
return str.substring(0, str.length() - 4);
// (m > 1) ENCE ->
}
else if ((str.endsWith("ence")) && (stringMeasure(str.substring(0, str.length() - 4)) > 1)) {
return str.substring(0, str.length() - 4);
// (m > 1) ER ->
}
else if ((str.endsWith("er")) && (stringMeasure(str.substring(0, str.length() - 2)) > 1)) {
return str.substring(0, str.length() - 2);
// (m > 1) IC ->
}
else if ((str.endsWith("ic")) && (stringMeasure(str.substring(0, str.length() - 2)) > 1)) {
return str.substring(0, str.length() - 2);
// (m > 1) ABLE ->
}
else if ((str.endsWith("able")) && (stringMeasure(str.substring(0, str.length() - 4)) > 1)) {
return str.substring(0, str.length() - 4);
// (m > 1) IBLE ->
}
else if ((str.endsWith("ible")) && (stringMeasure(str.substring(0, str.length() - 4)) > 1)) {
return str.substring(0, str.length() - 4);
// (m > 1) ANT ->
}
else if ((str.endsWith("ant")) && (stringMeasure(str.substring(0, str.length() - 3)) > 1)) {
return str.substring(0, str.length() - 3);
// (m > 1) EMENT ->
}
else if ((str.endsWith("ement")) && (stringMeasure(str.substring(0, str.length() - 5)) > 1)) {
return str.substring(0, str.length() - 5);
// (m > 1) MENT ->
}
else if ((str.endsWith("ment")) && (stringMeasure(str.substring(0, str.length() - 4)) > 1)) {
return str.substring(0, str.length() - 4);
// (m > 1) ENT ->
}
else if ((str.endsWith("ent")) && (stringMeasure(str.substring(0, str.length() - 3)) > 1)) {
return str.substring(0, str.length() - 3);
// (m > 1) and (*S or *T) ION ->
}
else if ((str.endsWith("sion") || str.endsWith("tion")) && (stringMeasure(str.substring(0, str.length() - 3)) > 1)) {
return str.substring(0, str.length() - 3);
// (m > 1) OU ->
}
else if ((str.endsWith("ou")) && (stringMeasure(str.substring(0, str.length() - 2)) > 1)) {
return str.substring(0, str.length() - 2);
// (m > 1) ISM ->
}
else if ((str.endsWith("ism")) && (stringMeasure(str.substring(0, str.length() - 3)) > 1)) {
return str.substring(0, str.length() - 3);
// (m > 1) ATE ->
}
else if ((str.endsWith("ate")) && (stringMeasure(str.substring(0, str.length() - 3)) > 1)) {
return str.substring(0, str.length() - 3);
// (m > 1) ITI ->
}
else if ((str.endsWith("iti")) && (stringMeasure(str.substring(0, str.length() - 3)) > 1)) {
return str.substring(0, str.length() - 3);
// (m > 1) OUS ->
}
else if ((str.endsWith("ous")) && (stringMeasure(str.substring(0, str.length() - 3)) > 1)) {
return str.substring(0, str.length() - 3);
// (m > 1) IVE ->
}
else if ((str.endsWith("ive")) && (stringMeasure(str.substring(0, str.length() - 3)) > 1)) {
return str.substring(0, str.length() - 3);
// (m > 1) IZE ->
}
else if ((str.endsWith("ize")) && (stringMeasure(str.substring(0, str.length() - 3)) > 1)) {
return str.substring(0, str.length() - 3);
}
return str;
}
private static String step5a(String str) {
// (m > 1) E ->
if (str.endsWith("e") && stringMeasure(str.substring(0, str.length() - 1)) > 1) {
return str.substring(0, str.length() - 1);
}
// (m = 1 and not *0) E ->
else
if (str.endsWith("e") && stringMeasure(str.substring(0, str.length() - 1)) == 1 && !endsWithCVC(str.substring(0, str.length() - 1))) {
return str.substring(0, str.length() - 1);
}
else {
return str;
}
}
private static String step5b(String str) {
// (m > 1 and *d and *L) ->
if (str.endsWith("l") && stringMeasure(str.substring(0, str.length() - 1)) > 1 && endsWithDoubleConsonent(str)) {
return str.substring(0, str.length() - 1);
}
else {
return str;
}
}
private static boolean containsVowel(String str) {
char[] strchars = str.toCharArray();
for (char strchar : strchars) {
if (isVowel(strchar)) return true;
}
// no aeiou but there is y
if (str.indexOf('y') > -1) {
return true;
}
else {
return false;
}
}
private static boolean isVowel(char c) {
if ((c == 'a') || (c == 'e') || (c == 'i') || (c == 'o') || (c == 'u')) {
return true;
}
else {
return false;
}
}
private static boolean endsWithDoubleConsonent(String str) {
char c = str.charAt(str.length() - 1);
if (str.length() > 1 && c == str.charAt(str.length() - 2)) {
if (!containsVowel(str.substring(str.length() - 2))) {
return true;
}
}
return false;
}
// returns a CVC measure for the string
private static int stringMeasure(String str) {
int count = 0;
boolean vowelSeen = false;
char[] strchars = str.toCharArray();
for (char strchar : strchars) {
if (isVowel(strchar)) {
vowelSeen = true;
}
else if (vowelSeen) {
count++;
vowelSeen = false;
}
}
return count;
}
private static boolean endsWithCVC(String str) {
char c;
char v;
char c2;
if (str.length() >= 3) {
c = str.charAt(str.length() - 1);
v = str.charAt(str.length() - 2);
c2 = str.charAt(str.length() - 3);
}
else {
return false;
}
if ((c == 'w') || (c == 'x') || (c == 'y')) {
return false;
}
else if (isVowel(c)) {
return false;
}
else if (!isVowel(v)) {
return false;
}
else if (isVowel(c2)) {
return false;
}
else {
return true;
}
}
}