Source code

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 */
017package org.apache.commons.lang3;
018
019/**
020 * Operations on {@link CharSequence} that are
021 * {@code null} safe.
022 *
023 * @see CharSequence
024 * @since 3.0
025 */
026public class CharSequenceUtils {
027
028    private static final int NOT_FOUND = -1;
029
030    static final int TO_STRING_LIMIT = 16;
031
032    private static boolean checkLaterThan1(final CharSequence cs, final CharSequence searchChar, final int len2, final int start1) {
033        for (int i = 1, j = len2 - 1; i <= j; i++, j--) {
034            if (cs.charAt(start1 + i) != searchChar.charAt(i) || cs.charAt(start1 + j) != searchChar.charAt(j)) {
035                return false;
036            }
037        }
038        return true;
039    }
040
041    /**
042     * Used by the indexOf(CharSequence methods) as a green implementation of indexOf.
043     *
044     * @param cs the {@link CharSequence} to be processed
045     * @param searchChar the {@link CharSequence} to be searched for
046     * @param start the start index
047     * @return the index where the search sequence was found
048     */
049    static int indexOf(final CharSequence cs, final CharSequence searchChar, final int start) {
050        if (cs instanceof String) {
051            return ((String) cs).indexOf(searchChar.toString(), start);
052        }
053        if (cs instanceof StringBuilder) {
054            return ((StringBuilder) cs).indexOf(searchChar.toString(), start);
055        }
056        if (cs instanceof StringBuffer) {
057            return ((StringBuffer) cs).indexOf(searchChar.toString(), start);
058        }
059        return cs.toString().indexOf(searchChar.toString(), start);
060//        if (cs instanceof String && searchChar instanceof String) {
061//            // TODO: Do we assume searchChar is usually relatively small;
062//            //       If so then calling toString() on it is better than reverting to
063//            //       the green implementation in the else block
064//            return ((String) cs).indexOf((String) searchChar, start);
065//        } else {
066//            // TODO: Implement rather than convert to String
067//            return cs.toString().indexOf(searchChar.toString(), start);
068//        }
069    }
070
071    /**
072     * Returns the index within {@code cs} of the first occurrence of the
073     * specified character, starting the search at the specified index.
074     * <p>
075     * If a character with value {@code searchChar} occurs in the
076     * character sequence represented by the {@code cs}
077     * object at an index no smaller than {@code start}, then
078     * the index of the first such occurrence is returned. For values
079     * of {@code searchChar} in the range from 0 to 0xFFFF (inclusive),
080     * this is the smallest value <i>k</i> such that:
081     * </p>
082     * <blockquote><pre>
083     * (this.charAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &gt;= start)
084     * </pre></blockquote>
085     * is true. For other values of {@code searchChar}, it is the
086     * smallest value <i>k</i> such that:
087     * <blockquote><pre>
088     * (this.codePointAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &gt;= start)
089     * </pre></blockquote>
090     * <p>
091     * is true. In either case, if no such character occurs inm {@code cs}
092     * at or after position {@code start}, then
093     * {@code -1} is returned.
094     * </p>
095     * <p>
096     * There is no restriction on the value of {@code start}. If it
097     * is negative, it has the same effect as if it were zero: the entire
098     * {@link CharSequence} may be searched. If it is greater than
099     * the length of {@code cs}, it has the same effect as if it were
100     * equal to the length of {@code cs}: {@code -1} is returned.
101     * </p>
102     * <p>All indices are specified in {@code char} values
103     * (Unicode code units).
104     * </p>
105     *
106     * @param cs  the {@link CharSequence} to be processed, not null
107     * @param searchChar  the char to be searched for
108     * @param start  the start index, negative starts at the string start
109     * @return the index where the search char was found, -1 if not found
110     * @since 3.6 updated to behave more like {@link String}
111     */
112    static int indexOf(final CharSequence cs, final int searchChar, int start) {
113        if (cs instanceof String) {
114            return ((String) cs).indexOf(searchChar, start);
115        }
116        final int sz = cs.length();
117        if (start < 0) {
118            start = 0;
119        }
120        if (searchChar < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
121            for (int i = start; i < sz; i++) {
122                if (cs.charAt(i) == searchChar) {
123                    return i;
124                }
125            }
126            return NOT_FOUND;
127        }
128        //supplementary characters (LANG1300)
129        if (searchChar <= Character.MAX_CODE_POINT) {
130            final char[] chars = Character.toChars(searchChar);
131            for (int i = start; i < sz - 1; i++) {
132                final char high = cs.charAt(i);
133                final char low = cs.charAt(i + 1);
134                if (high == chars[0] && low == chars[1]) {
135                    return i;
136                }
137            }
138        }
139        return NOT_FOUND;
140    }
141
142    /**
143     * Used by the lastIndexOf(CharSequence methods) as a green implementation of lastIndexOf
144     *
145     * @param cs the {@link CharSequence} to be processed
146     * @param searchChar the {@link CharSequence} to find
147     * @param start the start index
148     * @return the index where the search sequence was found
149     */
150    static int lastIndexOf(final CharSequence cs, final CharSequence searchChar, int start) {
151        if (searchChar == null || cs == null) {
152            return NOT_FOUND;
153        }
154        if (searchChar instanceof String) {
155            if (cs instanceof String) {
156                return ((String) cs).lastIndexOf((String) searchChar, start);
157            }
158            if (cs instanceof StringBuilder) {
159                return ((StringBuilder) cs).lastIndexOf((String) searchChar, start);
160            }
161            if (cs instanceof StringBuffer) {
162                return ((StringBuffer) cs).lastIndexOf((String) searchChar, start);
163            }
164        }
165
166        final int len1 = cs.length();
167        final int len2 = searchChar.length();
168
169        if (start > len1) {
170            start = len1;
171        }
172
173        if (start < 0 || len2 > len1) {
174            return NOT_FOUND;
175        }
176
177        if (len2 == 0) {
178            return start;
179        }
180
181        if (len2 <= TO_STRING_LIMIT) {
182            if (cs instanceof String) {
183                return ((String) cs).lastIndexOf(searchChar.toString(), start);
184            }
185            if (cs instanceof StringBuilder) {
186                return ((StringBuilder) cs).lastIndexOf(searchChar.toString(), start);
187            }
188            if (cs instanceof StringBuffer) {
189                return ((StringBuffer) cs).lastIndexOf(searchChar.toString(), start);
190            }
191        }
192
193        if (start + len2 > len1) {
194            start = len1 - len2;
195        }
196
197        final char char0 = searchChar.charAt(0);
198
199        int i = start;
200        while (true) {
201            while (cs.charAt(i) != char0) {
202                i--;
203                if (i < 0) {
204                    return NOT_FOUND;
205                }
206            }
207            if (checkLaterThan1(cs, searchChar, len2, i)) {
208                return i;
209            }
210            i--;
211            if (i < 0) {
212                return NOT_FOUND;
213            }
214        }
215    }
216
217    /**
218     * Returns the index within {@code cs} of the last occurrence of
219     * the specified character, searching backward starting at the
220     * specified index. For values of {@code searchChar} in the range
221     * from 0 to 0xFFFF (inclusive), the index returned is the largest
222     * value <i>k</i> such that:
223     * <blockquote><pre>
224     * (this.charAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &lt;= start)
225     * </pre></blockquote>
226     * is true. For other values of {@code searchChar}, it is the
227     * largest value <i>k</i> such that:
228     * <blockquote><pre>
229     * (this.codePointAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &lt;= start)
230     * </pre></blockquote>
231     * is true. In either case, if no such character occurs in {@code cs}
232     * at or before position {@code start}, then {@code -1} is returned.
233     *
234     * <p>
235     * All indices are specified in {@code char} values
236     * (Unicode code units).
237     * </p>
238     *
239     * @param cs  the {@link CharSequence} to be processed
240     * @param searchChar  the char to be searched for
241     * @param start  the start index, negative returns -1, beyond length starts at end
242     * @return the index where the search char was found, -1 if not found
243     * @since 3.6 updated to behave more like {@link String}
244     */
245    static int lastIndexOf(final CharSequence cs, final int searchChar, int start) {
246        if (cs instanceof String) {
247            return ((String) cs).lastIndexOf(searchChar, start);
248        }
249        final int sz = cs.length();
250        if (start < 0) {
251            return NOT_FOUND;
252        }
253        if (start >= sz) {
254            start = sz - 1;
255        }
256        if (searchChar < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
257            for (int i = start; i >= 0; --i) {
258                if (cs.charAt(i) == searchChar) {
259                    return i;
260                }
261            }
262            return NOT_FOUND;
263        }
264        //supplementary characters (LANG1300)
265        //NOTE - we must do a forward traversal for this to avoid duplicating code points
266        if (searchChar <= Character.MAX_CODE_POINT) {
267            final char[] chars = Character.toChars(searchChar);
268            //make sure it's not the last index
269            if (start == sz - 1) {
270                return NOT_FOUND;
271            }
272            for (int i = start; i >= 0; i--) {
273                final char high = cs.charAt(i);
274                final char low = cs.charAt(i + 1);
275                if (chars[0] == high && chars[1] == low) {
276                    return i;
277                }
278            }
279        }
280        return NOT_FOUND;
281    }
282
283    /**
284     * Green implementation of regionMatches.
285     *
286     * @param cs the {@link CharSequence} to be processed
287     * @param ignoreCase whether or not to be case-insensitive
288     * @param thisStart the index to start on the {@code cs} CharSequence
289     * @param substring the {@link CharSequence} to be looked for
290     * @param start the index to start on the {@code substring} CharSequence
291     * @param length character length of the region
292     * @return whether the region matched
293     */
294    static boolean regionMatches(final CharSequence cs, final boolean ignoreCase, final int thisStart,
295            final CharSequence substring, final int start, final int length)    {
296        if (cs instanceof String && substring instanceof String) {
297            return ((String) cs).regionMatches(ignoreCase, thisStart, (String) substring, start, length);
298        }
299        int index1 = thisStart;
300        int index2 = start;
301        int tmpLen = length;
302
303        // Extract these first so we detect NPEs the same as the java.lang.String version
304        final int srcLen = cs.length() - thisStart;
305        final int otherLen = substring.length() - start;
306
307        // Check for invalid parameters
308        if (thisStart < 0 || start < 0 || length < 0) {
309            return false;
310        }
311
312        // Check that the regions are long enough
313        if (srcLen < length || otherLen < length) {
314            return false;
315        }
316
317        while (tmpLen-- > 0) {
318            final char c1 = cs.charAt(index1++);
319            final char c2 = substring.charAt(index2++);
320
321            if (c1 == c2) {
322                continue;
323            }
324
325            if (!ignoreCase) {
326                return false;
327            }
328
329            // The real same check as in String.regionMatches():
330            final char u1 = Character.toUpperCase(c1);
331            final char u2 = Character.toUpperCase(c2);
332            if (u1 != u2 && Character.toLowerCase(u1) != Character.toLowerCase(u2)) {
333                return false;
334            }
335        }
336
337        return true;
338    }
339
340    /**
341     * Returns a new {@link CharSequence} that is a subsequence of this
342     * sequence starting with the {@code char} value at the specified index.
343     *
344     * <p>This provides the {@link CharSequence} equivalent to {@link String#substring(int)}.
345     * The length (in {@code char}) of the returned sequence is {@code length() - start},
346     * so if {@code start == end} then an empty sequence is returned.</p>
347     *
348     * @param cs  the specified subsequence, null returns null
349     * @param start  the start index, inclusive, valid
350     * @return a new subsequence, may be null
351     * @throws IndexOutOfBoundsException if {@code start} is negative or if
352     *  {@code start} is greater than {@code length()}
353     */
354    public static CharSequence subSequence(final CharSequence cs, final int start) {
355        return cs == null ? null : cs.subSequence(start, cs.length());
356    }
357
358    /**
359     * Converts the given CharSequence to a char[].
360     *
361     * @param source the {@link CharSequence} to be processed.
362     * @return the resulting char array, never null.
363     * @since 3.11
364     */
365    public static char[] toCharArray(final CharSequence source) {
366        final int len = StringUtils.length(source);
367        if (len == 0) {
368            return ArrayUtils.EMPTY_CHAR_ARRAY;
369        }
370        if (source instanceof String) {
371            return ((String) source).toCharArray();
372        }
373        final char[] array = new char[len];
374        for (int i = 0; i < len; i++) {
375            array[i] = source.charAt(i);
376        }
377        return array;
378    }
379
380    /**
381     * {@link CharSequenceUtils} instances should NOT be constructed in
382     * standard programming.
383     *
384     * <p>This constructor is public to permit tools that require a JavaBean
385     * instance to operate.</p>
386     */
387    public CharSequenceUtils() {
388    }
389}