001/*
002 * Copyright 2009 Red Hat, Inc.
003 * Red Hat licenses this file to you under the Apache License, version
004 * 2.0 (the "License"); you may not use this file except in compliance
005 * with the License.  You may obtain a copy of the License at
006 *    http://www.apache.org/licenses/LICENSE-2.0
007 * Unless required by applicable law or agreed to in writing, software
008 * distributed under the License is distributed on an "AS IS" BASIS,
009 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
010 * implied.  See the License for the specific language governing
011 * permissions and limitations under the License.
012 */
013
014package org.hornetq.api.core;
015
016import java.io.Serializable;
017import java.util.ArrayList;
018import java.util.List;
019
020import org.hornetq.core.logging.Logger;
021import org.hornetq.utils.DataConstants;
022
023/**
024 * A simple String class that can store all characters, and stores as simple byte[],
025 * this minimises expensive copying between String objects.
026 *
027 * This object is used heavily throughout HornetQ for performance reasons.
028 *
029 * @author <a href="mailto:tim.fox@jboss.com">Tim Fox</a>
030 *
031 */
032
033public class SimpleString implements CharSequence, Serializable, Comparable<SimpleString>
034{
035   private static final long serialVersionUID = 4204223851422244307L;
036
037   private static final Logger log = Logger.getLogger(SimpleString.class);
038
039   // Attributes
040   // ------------------------------------------------------------------------
041   private final byte[] data;
042
043   private transient int hash;
044
045   // Cache the string
046   private transient String str;
047
048   // Static
049   // ----------------------------------------------------------------------
050
051   /**
052    * Returns a SimpleString constructed from the <code>string</code> parameter.
053    * If <code>string</code> is <code>null</code>, the return value will be <code>null</code> too.
054    */
055   public static SimpleString toSimpleString(final String string)
056   {
057      if (string == null)
058      {
059         return null;
060      }
061      return new SimpleString(string);
062   }
063
064   // Constructors
065   // ----------------------------------------------------------------------
066   /**
067    * creates a SimpleString from a conventional String
068    * @param string the string to transform
069    */
070   public SimpleString(final String string)
071   {
072      int len = string.length();
073
074      data = new byte[len << 1];
075
076      int j = 0;
077
078      for (int i = 0; i < len; i++)
079      {
080         char c = string.charAt(i);
081
082         byte low = (byte)(c & 0xFF); // low byte
083
084         data[j++] = low;
085
086         byte high = (byte)(c >> 8 & 0xFF); // high byte
087
088         data[j++] = high;
089      }
090
091      str = string;
092   }
093
094   /**
095    * creates a SimpleString from a byte array
096    * @param data the byte array to use
097    */
098   public SimpleString(final byte[] data)
099   {
100      this.data = data;
101   }
102
103   // CharSequence implementation
104   // ---------------------------------------------------------------------------
105
106   public int length()
107   {
108      return data.length >> 1;
109   }
110
111   public char charAt(int pos)
112   {
113      if (pos < 0 || pos >= data.length >> 1)
114      {
115         throw new IndexOutOfBoundsException();
116      }
117      pos <<= 1;
118
119      return (char)((data[pos] & 0xFF) | (data[pos + 1] << 8) & 0xFF00);
120   }
121
122   public CharSequence subSequence(final int start, final int end)
123   {
124      int len = data.length >> 1;
125
126      if (end < start || start < 0 || end > len)
127      {
128         throw new IndexOutOfBoundsException();
129      }
130      else
131      {
132         int newlen = end - start << 1;
133         byte[] bytes = new byte[newlen];
134
135         System.arraycopy(data, start << 1, bytes, 0, newlen);
136
137         return new SimpleString(bytes);
138      }
139   }
140
141   // Comparable implementation -------------------------------------
142
143   public int compareTo(final SimpleString o)
144   {
145      return toString().compareTo(o.toString());
146   }
147
148   // Public
149   // ---------------------------------------------------------------------------
150
151   /**
152    * returns the underlying byte array of this SimpleString
153    * @return the byte array
154    */
155   public byte[] getData()
156   {
157      return data;
158   }
159
160   /**
161    * returns true if the SimpleString parameter starts with the same data as this one. false if not.
162    * @param other the SimpelString to look for
163    * @return true if this SimpleString starts with the same data
164    */
165   public boolean startsWith(final SimpleString other)
166   {
167      byte[] otherdata = other.data;
168
169      if (otherdata.length > data.length)
170      {
171         return false;
172      }
173
174      for (int i = 0; i < otherdata.length; i++)
175      {
176         if (data[i] != otherdata[i])
177         {
178            return false;
179         }
180      }
181
182      return true;
183   }
184
185   @Override
186   public String toString()
187   {
188      if (str == null)
189      {
190         int len = data.length >> 1;
191
192         char[] chars = new char[len];
193
194         int j = 0;
195
196         for (int i = 0; i < len; i++)
197         {
198            int low = data[j++] & 0xFF;
199
200            int high = data[j++] << 8 & 0xFF00;
201
202            chars[i] = (char)(low | high);
203         }
204
205         str = new String(chars);
206      }
207
208      return str;
209   }
210
211   @Override
212   public boolean equals(final Object other)
213   {
214      if (this == other)
215      {
216         return true;
217      }
218
219      if (other instanceof SimpleString)
220      {
221         SimpleString s = (SimpleString)other;
222
223         if (data.length != s.data.length)
224         {
225            return false;
226         }
227
228         for (int i = 0; i < data.length; i++)
229         {
230            if (data[i] != s.data[i])
231            {
232               return false;
233            }
234         }
235
236         return true;
237      }
238      else
239      {
240         return false;
241      }
242   }
243
244   @Override
245   public int hashCode()
246   {
247      if (hash == 0)
248      {
249         int tmphash = 0;
250         for (byte element : data)
251         {
252            tmphash = (tmphash << 5) - tmphash + element; // (hash << 5) - hash is same as hash * 31
253         }
254         hash = tmphash;
255      }
256
257      return hash;
258   }
259
260   /**
261    * Splits this SimpleString into an array of SimpleString using the char param as the delimiter.
262    * i.e. "a.b" would return "a" and "b" if . was the delimiter
263    * @param delim
264    */
265   public SimpleString[] split(final char delim)
266   {
267      if (!contains(delim))
268      {
269         return new SimpleString[] { this };
270      }
271      else
272      {
273         List<SimpleString> all = new ArrayList<SimpleString>();
274
275         byte low = (byte)(delim & 0xFF); // low byte
276         byte high = (byte)(delim >> 8 & 0xFF); // high byte
277
278         int lasPos = 0;
279         for (int i = 0; i < data.length; i += 2)
280         {
281            if (data[i] == low && data[i + 1] == high)
282            {
283               byte[] bytes = new byte[i - lasPos];
284               System.arraycopy(data, lasPos, bytes, 0, bytes.length);
285               lasPos = i + 2;
286               all.add(new SimpleString(bytes));
287            }
288         }
289         byte[] bytes = new byte[data.length - lasPos];
290         System.arraycopy(data, lasPos, bytes, 0, bytes.length);
291         all.add(new SimpleString(bytes));
292         SimpleString[] parts = new SimpleString[all.size()];
293         return all.toArray(parts);
294      }
295   }
296
297   /**
298    * checks to see if this SimpleString contains the char parameter passed in
299    *
300    * @param c the char to check for
301    * @return true if the char is found, false otherwise.
302    */
303   public boolean contains(final char c)
304   {
305      final byte low = (byte)(c & 0xFF); // low byte
306      final byte high = (byte)(c >> 8 & 0xFF); // high byte
307
308      for (int i = 0; i < data.length; i += 2)
309      {
310         if (data[i] == low && data[i + 1] == high)
311         {
312            return true;
313         }
314      }
315      return false;
316   }
317
318   /**
319    * Concatenates a SimpleString and a String
320    * @param toAdd the String to concatenate with.
321    * @return the concatenated SimpleString
322    */
323   public SimpleString concat(final String toAdd)
324   {
325      return concat(new SimpleString(toAdd));
326   }
327
328   /**
329    * Concatenates 2 SimpleString's
330    * @param toAdd the SimpleString to concatenate with.
331    * @return the concatenated SimpleString
332    */
333   public SimpleString concat(final SimpleString toAdd)
334   {
335      byte[] bytes = new byte[data.length + toAdd.getData().length];
336      System.arraycopy(data, 0, bytes, 0, data.length);
337      System.arraycopy(toAdd.getData(), 0, bytes, data.length, toAdd.getData().length);
338      return new SimpleString(bytes);
339   }
340
341   /**
342    * Concatenates a SimpleString and a char
343    * @param c the char to concate with.
344    * @return the concatenated SimpleString
345    */
346   public SimpleString concat(final char c)
347   {
348      byte[] bytes = new byte[data.length + 2];
349      System.arraycopy(data, 0, bytes, 0, data.length);
350      bytes[data.length] = (byte)(c & 0xFF);
351      bytes[data.length + 1] = (byte)(c >> 8 & 0xFF);
352      return new SimpleString(bytes);
353   }
354
355   /**
356    * returns the size of this SimpleString
357    * @return the size
358    */
359   public int sizeof()
360   {
361      return DataConstants.SIZE_INT + data.length;
362   }
363
364   /**
365    * returns the size of a SimpleString
366    * @param str the SimpleString to check
367    * @return the size
368    */
369   public static int sizeofString(final SimpleString str)
370   {
371      return str.sizeof();
372   }
373
374   /**
375    * returns the size of a SimpleString which could be null
376    * @param str the SimpleString to check
377    * @return the size
378    */
379   public static int sizeofNullableString(final SimpleString str)
380   {
381      if (str == null)
382      {
383         return 1;
384      }
385      else
386      {
387         return 1 + str.sizeof();
388      }
389   }
390
391   /**
392    *
393    * @param srcBegin
394    * @param srcEnd
395    * @param dst
396    * @param dstBegin
397    */
398   public void getChars(final int srcBegin, final int srcEnd, final char dst[], final int dstBegin)
399   {
400      if (srcBegin < 0)
401      {
402         throw new StringIndexOutOfBoundsException(srcBegin);
403      }
404      if (srcEnd > length())
405      {
406         throw new StringIndexOutOfBoundsException(srcEnd);
407      }
408      if (srcBegin > srcEnd)
409      {
410         throw new StringIndexOutOfBoundsException(srcEnd - srcBegin);
411      }
412
413      int j = 0;
414
415      for (int i = srcBegin; i < srcEnd - srcBegin; i++)
416      {
417         int low = data[j++] & 0xFF;
418
419         int high = data[j++] << 8 & 0xFF00;
420
421         dst[i] = (char)(low | high);
422      }
423   }
424
425}