opennlp.tools.tokenize.SimpleTokenizer 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.tokenize;
import java.util.ArrayList;
import java.util.List;
import opennlp.tools.util.Span;
import opennlp.tools.util.StringUtil;
/**
* A basic {@link Tokenizer} implementation which performs tokenization
* using character classes.
*
* To obtain an instance of this tokenizer use the static final
* {@link #INSTANCE} field.
*/
public class SimpleTokenizer extends AbstractTokenizer {
static class CharacterEnum {
static final CharacterEnum WHITESPACE = new CharacterEnum("whitespace");
static final CharacterEnum ALPHABETIC = new CharacterEnum("alphabetic");
static final CharacterEnum NUMERIC = new CharacterEnum("numeric");
static final CharacterEnum OTHER = new CharacterEnum("other");
private final String name;
private CharacterEnum(String name) {
this.name = name;
}
@Override
public String toString() {
return name;
}
}
/**
* Use this static reference to retrieve an instance of the
* {@link SimpleTokenizer}.
*/
public static final SimpleTokenizer INSTANCE = new SimpleTokenizer();
private SimpleTokenizer() {
}
@Override
public Span[] tokenizePos(String s) {
CharacterEnum charType = CharacterEnum.WHITESPACE;
CharacterEnum state = charType;
List tokens = new ArrayList<>();
int sl = s.length();
int start = -1;
char pc = 0;
for (int ci = 0; ci < sl; ci++) {
char c = s.charAt(ci);
if (StringUtil.isWhitespace(c)) {
charType = CharacterEnum.WHITESPACE;
}
else if (Character.isAlphabetic(c)) {
charType = CharacterEnum.ALPHABETIC;
}
else if (Character.isDigit(c)) {
charType = CharacterEnum.NUMERIC;
}
else {
charType = CharacterEnum.OTHER;
}
if (state == CharacterEnum.WHITESPACE) {
if (charType != CharacterEnum.WHITESPACE) {
start = ci;
}
}
else {
if (charType != state || charType == CharacterEnum.OTHER && c != pc) {
tokens.add(new Span(start, ci));
start = ci;
}
}
if (keepNewLines && isLineSeparator(c)) {
tokens.add(new Span(start, start + 1));
start = start + 1;
}
state = charType;
pc = c;
}
if (charType != CharacterEnum.WHITESPACE) {
tokens.add(new Span(start, sl));
}
return tokens.toArray(new Span[0]);
}
private boolean isLineSeparator(char character) {
return character == Character.LINE_SEPARATOR || character == Character.LETTER_NUMBER;
}
}