001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     * 
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     * 
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.io;
018    
019    import java.io.Serializable;
020    
021    /**
022     * Enumeration of IO case sensitivity.
023     * <p>
024     * Different filing systems have different rules for case-sensitivity.
025     * Windows is case-insensitive, Unix is case-sensitive.
026     * <p>
027     * This class captures that difference, providing an enumeration to
028     * control how filename comparisons should be performed. It also provides
029     * methods that use the enumeration to perform comparisons.
030     * <p>
031     * Wherever possible, you should use the <code>check</code> methods in this
032     * class to compare filenames.
033     *
034     * @version $Id: IOCase.java 1304052 2012-03-22 20:55:29Z ggregory $
035     * @since 1.3
036     */
037    public final class IOCase implements Serializable {
038    
039        /**
040         * The constant for case sensitive regardless of operating system.
041         */
042        public static final IOCase SENSITIVE = new IOCase("Sensitive", true);
043        
044        /**
045         * The constant for case insensitive regardless of operating system.
046         */
047        public static final IOCase INSENSITIVE = new IOCase("Insensitive", false);
048        
049        /**
050         * The constant for case sensitivity determined by the current operating system.
051         * Windows is case-insensitive when comparing filenames, Unix is case-sensitive.
052         * <p>
053         * <strong>Note:</strong> This only caters for Windows and Unix. Other operating
054         * systems (e.g. OSX and OpenVMS) are treated as case sensitive if they use the
055         * Unix file separator and case-insensitive if they use the Windows file separator
056         * (see {@link java.io.File#separatorChar}).
057         * <p>
058         * If you derialize this constant of Windows, and deserialize on Unix, or vice
059         * versa, then the value of the case-sensitivity flag will change.
060         */
061        public static final IOCase SYSTEM = new IOCase("System", !FilenameUtils.isSystemWindows());
062    
063        /** Serialization version. */
064        private static final long serialVersionUID = -6343169151696340687L;
065    
066        /** The enumeration name. */
067        private final String name;
068        
069        /** The sensitivity flag. */
070        private final transient boolean sensitive;
071    
072        //-----------------------------------------------------------------------
073        /**
074         * Factory method to create an IOCase from a name.
075         * 
076         * @param name  the name to find
077         * @return the IOCase object
078         * @throws IllegalArgumentException if the name is invalid
079         */
080        public static IOCase forName(String name) {
081            if (IOCase.SENSITIVE.name.equals(name)){
082                return IOCase.SENSITIVE;
083            }
084            if (IOCase.INSENSITIVE.name.equals(name)){
085                return IOCase.INSENSITIVE;
086            }
087            if (IOCase.SYSTEM.name.equals(name)){
088                return IOCase.SYSTEM;
089            }
090            throw new IllegalArgumentException("Invalid IOCase name: " + name);
091        }
092    
093        //-----------------------------------------------------------------------
094        /**
095         * Private constructor.
096         * 
097         * @param name  the name
098         * @param sensitive  the sensitivity
099         */
100        private IOCase(String name, boolean sensitive) {
101            this.name = name;
102            this.sensitive = sensitive;
103        }
104    
105        /**
106         * Replaces the enumeration from the stream with a real one.
107         * This ensures that the correct flag is set for SYSTEM.
108         * 
109         * @return the resolved object
110         */
111        private Object readResolve() {
112            return forName(name);
113        }
114    
115        //-----------------------------------------------------------------------
116        /**
117         * Gets the name of the constant.
118         * 
119         * @return the name of the constant
120         */
121        public String getName() {
122            return name;
123        }
124    
125        /**
126         * Does the object represent case sensitive comparison.
127         * 
128         * @return true if case sensitive
129         */
130        public boolean isCaseSensitive() {
131            return sensitive;
132        }
133    
134        //-----------------------------------------------------------------------
135        /**
136         * Compares two strings using the case-sensitivity rule.
137         * <p>
138         * This method mimics {@link String#compareTo} but takes case-sensitivity
139         * into account.
140         * 
141         * @param str1  the first string to compare, not null
142         * @param str2  the second string to compare, not null
143         * @return true if equal using the case rules
144         * @throws NullPointerException if either string is null
145         */
146        public int checkCompareTo(String str1, String str2) {
147            if (str1 == null || str2 == null) {
148                throw new NullPointerException("The strings must not be null");
149            }
150            return sensitive ? str1.compareTo(str2) : str1.compareToIgnoreCase(str2);
151        }
152    
153        /**
154         * Compares two strings using the case-sensitivity rule.
155         * <p>
156         * This method mimics {@link String#equals} but takes case-sensitivity
157         * into account.
158         * 
159         * @param str1  the first string to compare, not null
160         * @param str2  the second string to compare, not null
161         * @return true if equal using the case rules
162         * @throws NullPointerException if either string is null
163         */
164        public boolean checkEquals(String str1, String str2) {
165            if (str1 == null || str2 == null) {
166                throw new NullPointerException("The strings must not be null");
167            }
168            return sensitive ? str1.equals(str2) : str1.equalsIgnoreCase(str2);
169        }
170    
171        /**
172         * Checks if one string starts with another using the case-sensitivity rule.
173         * <p>
174         * This method mimics {@link String#startsWith(String)} but takes case-sensitivity
175         * into account.
176         * 
177         * @param str  the string to check, not null
178         * @param start  the start to compare against, not null
179         * @return true if equal using the case rules
180         * @throws NullPointerException if either string is null
181         */
182        public boolean checkStartsWith(String str, String start) {
183            return str.regionMatches(!sensitive, 0, start, 0, start.length());
184        }
185    
186        /**
187         * Checks if one string ends with another using the case-sensitivity rule.
188         * <p>
189         * This method mimics {@link String#endsWith} but takes case-sensitivity
190         * into account.
191         * 
192         * @param str  the string to check, not null
193         * @param end  the end to compare against, not null
194         * @return true if equal using the case rules
195         * @throws NullPointerException if either string is null
196         */
197        public boolean checkEndsWith(String str, String end) {
198            int endLen = end.length();
199            return str.regionMatches(!sensitive, str.length() - endLen, end, 0, endLen);
200        }
201    
202        /**
203         * Checks if one string contains another starting at a specific index using the
204         * case-sensitivity rule.
205         * <p>
206         * This method mimics parts of {@link String#indexOf(String, int)} 
207         * but takes case-sensitivity into account.
208         * 
209         * @param str  the string to check, not null
210         * @param strStartIndex  the index to start at in str
211         * @param search  the start to search for, not null
212         * @return the first index of the search String,
213         *  -1 if no match or <code>null</code> string input
214         * @throws NullPointerException if either string is null
215         * @since 2.0
216         */
217        public int checkIndexOf(String str, int strStartIndex, String search) {
218            int endIndex = str.length() - search.length();
219            if (endIndex >= strStartIndex) {
220                for (int i = strStartIndex; i <= endIndex; i++) {
221                    if (checkRegionMatches(str, i, search)) {
222                        return i;
223                    }
224                }
225            }
226            return -1;
227        }
228    
229        /**
230         * Checks if one string contains another at a specific index using the case-sensitivity rule.
231         * <p>
232         * This method mimics parts of {@link String#regionMatches(boolean, int, String, int, int)} 
233         * but takes case-sensitivity into account.
234         * 
235         * @param str  the string to check, not null
236         * @param strStartIndex  the index to start at in str
237         * @param search  the start to search for, not null
238         * @return true if equal using the case rules
239         * @throws NullPointerException if either string is null
240         */
241        public boolean checkRegionMatches(String str, int strStartIndex, String search) {
242            return str.regionMatches(!sensitive, strStartIndex, search, 0, search.length());
243        }
244    
245        //-----------------------------------------------------------------------
246        /**
247         * Gets a string describing the sensitivity.
248         * 
249         * @return a string describing the sensitivity
250         */
251        @Override
252        public String toString() {
253            return name;
254        }
255    
256    }