content: /*
   * Copyright (c) 2016 the original author or authors.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all
   * copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   */
  
  package com.rivescript.util;
  
  import com.rivescript.regexp.Regexp;
  
  import java.util.HashSet;
  import java.util.Set;
  
  import static com.rivescript.regexp.Regexp.RE_NASTIES;
  
  /**
   * Miscellaneous {@link String} utility methods.
   *
   * @author Noah Petherbridge
   * @author Marcel Overdijk
   */
  public class StringUtils {
  
  	private static final char ESCAPE_CHAR = '\\';
  
  	private static final Set<Character> UNSAFE_CHARS = new HashSet<>();
  
  	static {
  		UNSAFE_CHARS.add('\\');
  		UNSAFE_CHARS.add('.');
  		UNSAFE_CHARS.add('+');
  		UNSAFE_CHARS.add('*');
  		UNSAFE_CHARS.add('?');
  		UNSAFE_CHARS.add('[');
  		UNSAFE_CHARS.add('^');
  		UNSAFE_CHARS.add(']');
  		UNSAFE_CHARS.add('$');
  		UNSAFE_CHARS.add('(');
  		UNSAFE_CHARS.add(')');
  		UNSAFE_CHARS.add('{');
  		UNSAFE_CHARS.add('}');
  		UNSAFE_CHARS.add('=');
  		UNSAFE_CHARS.add('!');
  		UNSAFE_CHARS.add('<');
  		UNSAFE_CHARS.add('>');
  		UNSAFE_CHARS.add('|');
  		UNSAFE_CHARS.add(':');
  	}
  
  	/**
  	 * Counts the number of words in a {@link String}.
  	 *
  	 * @param str the string to count
  	 * @param all count all
  	 * @return the number of words
  	 */
  	public static int countWords(String str, boolean all) {
  		if (str == null || str.length() == 0) {
  			return 0;
  		}
  		String[] words;
  		if (all) {
  			words = str.split("\\s+"); // Splits at whitespaces.
  		} else {
  			words = str.split("[\\s\\*\\#\\_\\|]+");
  		}
  
  		int count = 0;
  		for (String word : words) {
  			if (word.length() > 0) {
  				count++;
  			}
  		}
  
  		return count;
  	}
  
  	/**
  	 * Joins a {@link String} array into a single {@link String}.
  	 *
  	 * @param array     the array to join
  	 * @param delimiter the delimiter character to use, {@code null} is treated as {@code ""}
  	 */
  	public static String join(String[] array, String delimiter) {
  		if (array == null) {
  			return null;
  		}
  		if (delimiter == null) {
  			delimiter = "";
  		}
  		StringBuilder buf = new StringBuilder();
  		for (int i = 0; i < array.length; i++) {
  			buf.append(array[i]);
  			if (i < array.length - 1) {
  				buf.append(delimiter);
  			}
  		}
  		return buf.toString();
  	}
  
  	/**
  	 * Escapes a {@link String} for use in a regular expression.
  	 *
  	 * @param str the string to escape
  	 * @return the escaped string
  	 */
  	public static String quoteMetacharacters(String str) {
  		if (str == null) {
  			return null;
  		}
  
  		StringBuilder sb = new StringBuilder();
  		for (int i = 0; i < str.length(); i++) {
  			char c = str.charAt(i);
  			if (UNSAFE_CHARS.contains(c)) {
  				sb.append(ESCAPE_CHAR);
  			}
  			sb.append(c);
  		}
  
  		return sb.toString();
  	}
  
  	/**
  	 * Strips special characters out of a {@link String}.
  	 *
  	 * @param str the string to strip
  	 * @return the stripped string
  	 * @see Regexp#RE_NASTIES
  	 */
  	public static String stripNasties(String str) {
  		if (str == null) {
  			return null;
  		}
  		return RE_NASTIES.matcher(str).replaceAll("");
  	}
  }
  
  