Text.java

/*
 * aitools utilities
 * Copyright (C) 2006 Noel Bush
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

package org.aitools.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * Contains various utilities for manipulating text.
 * 
 * @author <a href="mailto:noel@aitools.org">Noel Bush</a>
 */
public class Text {

  /** The regex for splitting words at blank spaces. */
  public static final String WORD_SPLIT = "\\p{Blank}+";

  /** The system line separator. */
  private static final String LINE_SEPARATOR = System.getProperty("line.separator", "\n");

  /**
   * Returns the index of the last space block (one or more consecutive space characters) in the given StringBuilder.
   * 
   * @param builder
   * @return the index of the last whitespace block
   */
  public static int lastSpace(StringBuilder builder) {
    int index = builder.lastIndexOf(" ");
    if (index > -1) {
      while (builder.substring(index - 1, index).equals(" ")) {
        index--;
      }
    }
    return index;
  }

  /**
   * Merges the given list of char arrays into a single string.
   * 
   * @param list
   * @return the merged result
   */
  public static String mergeCharArrays(List<char[]> list) {
    return mergeCharArrays(list, 0, list.size());
  }

  /**
   * Merges the sublist between the given indices of given list of char arrays into a single string. (As in
   * {@link List#subList(int, int)}, <code>fromIndex</code> is inclusive and <code>toIndex</code> is exclusive).
   * 
   * @param list
   * @param fromIndex
   * @param toIndex
   * @return the merged result
   */
  public static String mergeCharArrays(List<char[]> list, int fromIndex, int toIndex) {
    StringBuilder result = new StringBuilder();
    for (char[] charlist : list.subList(fromIndex, toIndex)) {
      result.append(charlist);
    }
    return result.toString();
  }

  /**
   * Merges the given list of String arrays into a single string.
   * 
   * @param list
   * @return the merged result
   */
  public static String mergeStringArrays(List<String[]> list) {
    return mergeStringArrays(list, 0, list.size());
  }

  /**
   * Merges the sublist between the given indices of given list of String arrays into a single string. (As in
   * {@link List#subList(int, int)}, <code>fromIndex</code> is inclusive and <code>toIndex</code> is exclusive).
   * 
   * @param list
   * @param fromIndex
   * @param toIndex
   * @return the merged result
   */
  public static String mergeStringArrays(List<String[]> list, int fromIndex, int toIndex) {
    StringBuilder result = new StringBuilder();
    for (String[] string : list.subList(fromIndex, toIndex)) {
      result.append(string);
    }
    return result.toString();
  }

  /**
   * Turns an array of strings into a single string with line separators between each of the original strings.
   * 
   * @param strings the strings to render
   * @return the rendered strings
   */
  public static String renderAsLines(String[] strings) {
    int stringCount = strings.length;
    if (stringCount == 0) {
      return "";
    }
    StringBuilder result = new StringBuilder();
    for (int index = 0; index < stringCount - 1; index++) {
      result.append(strings[index]);
      result.append(LINE_SEPARATOR);
    }
    result.append(strings[stringCount - 1]);
    return result.toString();
  }

  /**
   * Returns a string of the specified number of repetitions of the given char.
   * 
   * @param character the character to repeat
   * @param count the number of repetitions
   * @return the requested string
   */
  public static String repeat(char character, int count) {
    char[] result = new char[count];
    Arrays.fill(result, character);
    return new String(result).intern();
  }

  /**
   * Returns a tab of the specified length.
   * 
   * @param level the level of the tab
   * @return the requested tab
   */
  public static String tab(int level) {
    return repeat('\t', level);
  }

  /**
   * Splits an input into words, breaking at word boundaries.
   * 
   * @param input the input to split
   * @return the input split into sentences
   */
  public static ArrayList<String> wordSplit(String input) {
    return new ArrayList<String>(Arrays.asList(input.split(WORD_SPLIT)));
  }
}