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;
import java.util.Objects;
import opennlp.tools.util.jvm.StringInterners;
/**
* A {@link StringList} is an immutable list of {@link String}s.
*/
public class StringList implements Iterable {
private final String[] tokens;
private final boolean caseSensitive;
/**
* Initializes a {@link StringList} instance. By default, this instance is case-sensitive.
*
* Note:
* Token String will be interned via {@link StringInterners}.
*
* @param singleToken One single token
*/
public StringList(String singleToken) {
this(true, singleToken);
}
/**
* Initializes a {@link StringList} instance. By default, this instance is case-sensitive.
*
* Note:
* Token Strings will be interned via {@link StringInterners}.
*
* @param tokens The string parts of the new {@link StringList}.
* Must not be an empty tokens array or {@code null}.
*
* @throws IllegalArgumentException Thrown if parameters were invalid.
*/
public StringList(String... tokens) {
this(true, tokens);
}
/**
* Initializes a {@link StringList} instance.
*
* Note:
* Token Strings will be interned via {@link StringInterners}.
*
* @param isCaseSensitive Whether it will operate case-sensitive, or not.
* @param tokens The string parts of the new {@link StringList}.
* Must not be an empty tokens array or {@code null}.
*
* @throws IllegalArgumentException Thrown if parameters were invalid.
*/
public StringList(boolean isCaseSensitive, String... tokens) {
Objects.requireNonNull(tokens, "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] = StringInterners.intern(tokens[i]);
}
this.caseSensitive = isCaseSensitive;
}
/**
* @param index The index to get a token from.
*
* @return Retrieves a token from the given {@code index}.
*/
public String getToken(int index) {
return tokens[index];
}
/**
* @return Retrieves the number of tokens inside this list.
*/
public int size() {
return tokens.length;
}
/**
* @return Retrieves an {@link Iterator} over all tokens.
*/
@Override
public Iterator iterator() {
return new Iterator<>() {
private int index;
@Override
public boolean hasNext() {
return index < size();
}
@Override
public String next() {
if (hasNext()) {
return getToken(index++);
}
else {
throw new NoSuchElementException();
}
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
};
}
/**
* Compares to {@link StringList token list} and ignores the case of the tokens.
* Note: This can cause problems with some locales.
*
* @param tokens The {@link StringList tokens} used for comparison.
*
* @return {@code true} if identically with ignore the case, {@code false} otherwise.
*/
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 int hashCode() {
// if lookup is too slow optimize this
return StringUtil.toLowerCase(toString()).hashCode();
}
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
} else if (obj instanceof StringList tokenList) {
if (caseSensitive) {
return Arrays.equals(tokens, tokenList.tokens);
} else {
return compareToIgnoreCase(tokenList);
}
}
return false;
}
/**
* @return A human-readable representation of this {@link StringList}.
*/
@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();
}
/**
* @return {@code true}, if this {@link StringList} is case-sensitive.
*/
public boolean isCaseSensitive() {
return caseSensitive;
}
/**
* @return If this {@link StringList} is case-insensitive,
* the same instance is returned. Otherwise, a new object is returned.
*/
public StringList toCaseInsensitive() {
if (isCaseSensitive()) {
return new StringList(false, tokens);
}
return this;
}
/**
* @return If this {@link StringList} is case-sensitive,
* the same instance is returned. Otherwise, a new object is returned.
*/
public StringList toCaseSensitive() {
if (!isCaseSensitive()) {
return new StringList(true, tokens);
}
return this;
}
}