/wordcounter/src/main/java/com/stoyanr/wordcounter/WordUtils.java

/*

 * $Id: $

 *

 * Copyright 2012 Stoyan Rachev (stoyanr@gmail.com)

 *

 * 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.stoyanr.wordcounter;



import java.util.function.UnaryOperator;



import com.stoyanr.util.CharPredicate;



/**

 * A utility class that provides several overloaded static methods for counting words in strings. 

 * The central method {@code countWords} accepts a string, a predicate to determine whether a 

 * character is a word character, and an optional unary operator to be performed on words. 

 * <p>

 * <pre>

 * // Count all words consisting of only alphabetic chars, ignoring case

 * WordCounts wc = WordUtils.countWords(text, (c) -> Character.isAlphabetic(c), (s) -> s.toLowerCase());

 * </pre>

 * 

 * @author Stoyan Rachev

 */

public class WordUtils {

    

    public static WordCounts countWords(String text, CharPredicate pred) {

        return countWords(text, pred, null);

    }



    public static WordCounts countWords(String text, CharPredicate pred, UnaryOperator<String> op) {

        assert (text != null);

        WordCounts result = new WordCounts();

        int i = 0;

        while (i < text.length()) {

            while (i < text.length() && !pred.test(text.charAt(i))) {

                i++;

            }

            int bi = i;

            while (i < text.length() && pred.test(text.charAt(i))) {

                i++;

            }

            int ei = i;

            if (bi != ei) {

                String word = text.substring(bi, ei);

                if (op != null) {

                    word = op.apply(word);

                }

                result.add(word, 1);

            }

        }

        return result;

    }

    

    public static int getEndWordIndex(String text, CharPredicate pred) {

        int ei = text.length();

        while (ei > 0 && pred.test(text.charAt(ei - 1))) {

            ei--;

        }

        return ei;

    }

}