opennlp.tools.util.StringList Maven / Gradle / Ivy
/*
* 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 opennlp.tools.util;
import java.util.Arrays;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* The {@link StringList} is an immutable list of {@link String}s.
*/
public class StringList implements Iterable {
private String tokens[];
/**
* Initializes the current instance.
*
* Note:
* Token String will be replaced by identical internal String object.
*
* @param singleToken one single token
*/
public StringList(String singleToken) {
tokens = new String[] {
singleToken.intern()
};
}
/**
* Initializes the current instance.
*
* Note:
* Token Strings will be replaced by identical internal String object.
*
* @param tokens the string parts of the new {@link StringList}, an empty
* tokens array or null is not permitted.
*/
public StringList(String... tokens) {
if (tokens == null) {
throw new IllegalArgumentException("tokens must not be null");
}
if (tokens.length == 0) {
throw new IllegalArgumentException("tokens must not be empty");
}
this.tokens = new String[tokens.length];
for (int i = 0; i < tokens.length; i++) {
this.tokens[i] = tokens[i].intern();
}
}
/**
* Retrieves a token from the given index.
*
* @param index
*
* @return token at the given index
*/
public String getToken(int index) {
return tokens[index];
}
/**
* Retrieves the number of tokens inside this list.
*
* @return number of tokens
*/
public int size() {
return tokens.length;
}
/**
* Retrieves an {@link Iterator} over all tokens.
*
* @return iterator over tokens
*/
public Iterator iterator() {
return new Iterator() {
private int index;
public boolean hasNext() {
return index < size();
}
public String next() {
if (hasNext()) {
return getToken(index++);
}
else {
throw new NoSuchElementException();
}
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
/**
* Compares to tokens list and ignores the case of the tokens.
*
* Note: This can cause problems with some locals.
*
* @param tokens
*
* @return true if identically with ignore the case otherwise false
*/
public boolean compareToIgnoreCase(StringList tokens) {
if (size() == tokens.size()) {
for (int i = 0; i < size(); i++) {
if (getToken(i).compareToIgnoreCase(
tokens.getToken(i)) != 0) {
return false;
}
}
}
else {
return false;
}
return true;
}
@Override
public boolean equals(Object obj) {
boolean result;
if (this == obj) {
result = true;
}
else if (obj instanceof StringList) {
StringList tokenList = (StringList) obj;
result = Arrays.equals(tokens, tokenList.tokens);
}
else {
result = false;
}
return result;
}
@Override
public int hashCode() {
int numBitsRegular = 32 / size();
int numExtra = 32 % size();
int maskExtra = 0xFFFFFFFF >>> (32 - numBitsRegular + 1);
int maskRegular = 0xFFFFFFFF >>> 32 - numBitsRegular;
int code = 0x000000000;
int leftMostBit = 0;
for (int wi = 0; wi < size(); wi++) {
int word;
int mask;
int numBits;
if (wi < numExtra) {
mask = maskExtra;
numBits = numBitsRegular + 1;
} else {
mask = maskRegular;
numBits = numBitsRegular;
}
word = getToken(wi).hashCode() & mask; // mask off top bits
word <<= 32 - leftMostBit - numBits; // move to correct position
leftMostBit += numBits; // set for next iteration
code |= word;
}
return code;
}
@Override
public String toString() {
StringBuilder string = new StringBuilder();
string.append('[');
for (int i = 0; i < size(); i++) {
string.append(getToken(i));
if (i < size() - 1) {
string.append(',');
}
}
string.append(']');
return string.toString();
}
}