smile.nlp.normalizer.SimpleNormalizer Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2010 Haifeng Li
*
* 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 smile.nlp.normalizer;
import java.util.regex.Pattern;
/**
* A baseline normalizer for processing Unicode text:
*
* - Apply Unicode normalization form NFKC.
* - Strip, trim, normalize, and compress whitespace.
* - Remove control and formatting characters.
* - Normalize double and single quotes.
*
*
* @author Mark Arehart
*/
public class SimpleNormalizer implements Normalizer {
private static final Pattern WHITESPACE = Pattern.compile("(?U)\\s+");
private static final Pattern CONTROL_FORMAT_CHARS = Pattern.compile("[\\p{Cc}\\p{Cf}]");
private static final Pattern DOUBLE_QUOTES = Pattern.compile("[\\u02BA\\u201C\\u201D\\u201E\\u201F\\u2033\\u2036\\u275D\\u275E\\u301D\\u301E\\u301F\\uFF02]");
private static final Pattern SINGLE_QUOTES = Pattern.compile("[\\u0060\\u02BB\\u02BC\\u02BD\\u2018\\u2019\\u201A\\u201B\\u275B\\u275C]");
/**
* The singleton instance.
*/
private static SimpleNormalizer singleton = new SimpleNormalizer();
/**
* Constructor.
*/
private SimpleNormalizer() { }
/**
* Returns the singleton instance.
*/
public static SimpleNormalizer getInstance() {
return singleton;
}
@Override
public String normalize(String text) {
text = text.trim();
if (!java.text.Normalizer.isNormalized(text, java.text.Normalizer.Form.NFKC)) {
text = java.text.Normalizer.normalize(text, java.text.Normalizer.Form.NFKC);
}
text = WHITESPACE.matcher(text).replaceAll(" ");
text = CONTROL_FORMAT_CHARS.matcher(text).replaceAll("");
text = DOUBLE_QUOTES.matcher(text).replaceAll("\"");
text = SINGLE_QUOTES.matcher(text).replaceAll("'");
return text;
}
}