code: /*
   * 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 org.apache.commons.io;
  
  import java.io.Serializable;
  
  /**
   * Enumeration of IO case sensitivity.
   * <p>
   * Different filing systems have different rules for case-sensitivity.
   * Windows is case-insensitive, Unix is case-sensitive.
   * <p>
   * This class captures that difference, providing an enumeration to
   * control how filename comparisons should be performed. It also provides
   * methods that use the enumeration to perform comparisons.
   * <p>
   * Wherever possible, you should use the <code>check</code> methods in this
   * class to compare filenames.
   *
   * @author Stephen Colebourne
   * @version $Id: IOCase.java 1003647 2010-10-01 20:53:59Z niallp $
   * @since Commons IO 1.3
   */
  public final class IOCase implements Serializable {
  
      /**
       * The constant for case sensitive regardless of operating system.
       */
      public static final IOCase SENSITIVE = new IOCase("Sensitive", true);
      
      /**
       * The constant for case insensitive regardless of operating system.
       */
      public static final IOCase INSENSITIVE = new IOCase("Insensitive", false);
      
      /**
       * The constant for case sensitivity determined by the current operating system.
       * Windows is case-insensitive when comparing filenames, Unix is case-sensitive.
       * <p>
       * <strong>Note:</strong> This only caters for Windows and Unix. Other operating
       * systems (e.g. OSX and OpenVMS) are treated as case sensitive if they use the
       * Unix file separator and case-insensitive if they use the Windows file separator
       * (see {@link java.io.File#separatorChar}).
       * <p>
       * If you derialize this constant of Windows, and deserialize on Unix, or vice
       * versa, then the value of the case-sensitivity flag will change.
       */
      public static final IOCase SYSTEM = new IOCase("System", !FilenameUtils.isSystemWindows());
  
      /** Serialization version. */
      private static final long serialVersionUID = -6343169151696340687L;
  
      /** The enumeration name. */
      private final String name;
      
      /** The sensitivity flag. */
      private final transient boolean sensitive;
  
      //-----------------------------------------------------------------------
      /**
       * Factory method to create an IOCase from a name.
       * 
       * @param name  the name to find
       * @return the IOCase object
       * @throws IllegalArgumentException if the name is invalid
       */
      public static IOCase forName(String name) {
          if (IOCase.SENSITIVE.name.equals(name)){
              return IOCase.SENSITIVE;
          }
          if (IOCase.INSENSITIVE.name.equals(name)){
              return IOCase.INSENSITIVE;
          }
          if (IOCase.SYSTEM.name.equals(name)){
              return IOCase.SYSTEM;
          }
          throw new IllegalArgumentException("Invalid IOCase name: " + name);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Private constructor.
       * 
       * @param name  the name
       * @param sensitive  the sensitivity
       */
      private IOCase(String name, boolean sensitive) {
          this.name = name;
          this.sensitive = sensitive;
      }
  
      /**
       * Replaces the enumeration from the stream with a real one.
       * This ensures that the correct flag is set for SYSTEM.
       * 
       * @return the resolved object
       */
      private Object readResolve() {
          return forName(name);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Gets the name of the constant.
       * 
       * @return the name of the constant
       */
      public String getName() {
          return name;
      }
  
      /**
       * Does the object represent case sensitive comparison.
       * 
       * @return true if case sensitive
       */
      public boolean isCaseSensitive() {
          return sensitive;
      }
  
      //-----------------------------------------------------------------------
      /**
       * Compares two strings using the case-sensitivity rule.
       * <p>
       * This method mimics {@link String#compareTo} but takes case-sensitivity
       * into account.
       * 
       * @param str1  the first string to compare, not null
       * @param str2  the second string to compare, not null
       * @return true if equal using the case rules
       * @throws NullPointerException if either string is null
       */
      public int checkCompareTo(String str1, String str2) {
          if (str1 == null || str2 == null) {
              throw new NullPointerException("The strings must not be null");
          }
          return sensitive ? str1.compareTo(str2) : str1.compareToIgnoreCase(str2);
      }
  
      /**
       * Compares two strings using the case-sensitivity rule.
       * <p>
       * This method mimics {@link String#equals} but takes case-sensitivity
       * into account.
       * 
       * @param str1  the first string to compare, not null
       * @param str2  the second string to compare, not null
       * @return true if equal using the case rules
       * @throws NullPointerException if either string is null
       */
      public boolean checkEquals(String str1, String str2) {
          if (str1 == null || str2 == null) {
              throw new NullPointerException("The strings must not be null");
          }
          return sensitive ? str1.equals(str2) : str1.equalsIgnoreCase(str2);
      }
  
      /**
       * Checks if one string starts with another using the case-sensitivity rule.
       * <p>
       * This method mimics {@link String#startsWith(String)} but takes case-sensitivity
       * into account.
       * 
       * @param str  the string to check, not null
       * @param start  the start to compare against, not null
       * @return true if equal using the case rules
       * @throws NullPointerException if either string is null
       */
      public boolean checkStartsWith(String str, String start) {
          return str.regionMatches(!sensitive, 0, start, 0, start.length());
      }
  
      /**
       * Checks if one string ends with another using the case-sensitivity rule.
       * <p>
       * This method mimics {@link String#endsWith} but takes case-sensitivity
       * into account.
       * 
       * @param str  the string to check, not null
       * @param end  the end to compare against, not null
       * @return true if equal using the case rules
       * @throws NullPointerException if either string is null
       */
      public boolean checkEndsWith(String str, String end) {
          int endLen = end.length();
          return str.regionMatches(!sensitive, str.length() - endLen, end, 0, endLen);
      }
  
      /**
       * Checks if one string contains another starting at a specific index using the
       * case-sensitivity rule.
       * <p>
       * This method mimics parts of {@link String#indexOf(String, int)} 
       * but takes case-sensitivity into account.
       * 
       * @param str  the string to check, not null
       * @param strStartIndex  the index to start at in str
       * @param search  the start to search for, not null
       * @return the first index of the search String,
       *  -1 if no match or <code>null</code> string input
       * @throws NullPointerException if either string is null
       * @since Commons IO 2.0
       */
      public int checkIndexOf(String str, int strStartIndex, String search) {
          int endIndex = str.length() - search.length();
          if (endIndex >= strStartIndex) {
              for (int i = strStartIndex; i <= endIndex; i++) {
                  if (checkRegionMatches(str, i, search)) {
                      return i;
                  }
              }
          }
          return -1;
      }
  
      /**
       * Checks if one string contains another at a specific index using the case-sensitivity rule.
       * <p>
       * This method mimics parts of {@link String#regionMatches(boolean, int, String, int, int)} 
       * but takes case-sensitivity into account.
       * 
       * @param str  the string to check, not null
       * @param strStartIndex  the index to start at in str
       * @param search  the start to search for, not null
       * @return true if equal using the case rules
       * @throws NullPointerException if either string is null
       */
      public boolean checkRegionMatches(String str, int strStartIndex, String search) {
          return str.regionMatches(!sensitive, strStartIndex, search, 0, search.length());
      }
  
      //-----------------------------------------------------------------------
      /**
       * Gets a string describing the sensitivity.
       * 
       * @return a string describing the sensitivity
       */
      @Override
      public String toString() {
          return name;
      }
  
  }
  