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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.util;
29  
30  import java.io.Serializable;
31  
32  import org.apache.http.annotation.NotThreadSafe;
33  
34  /**
35   * A resizable byte array.
36   *
37   * @since 4.0
38   */
39  @NotThreadSafe
40  public final class ByteArrayBuffer implements Serializable {
41  
42      private static final long serialVersionUID = 4359112959524048036L;
43  
44      private byte[] buffer;
45      private int len;
46  
47      /**
48       * Creates an instance of {@link ByteArrayBuffer} with the given initial
49       * capacity.
50       *
51       * @param capacity the capacity
52       */
53      public ByteArrayBuffer(int capacity) {
54          super();
55          if (capacity < 0) {
56              throw new IllegalArgumentException("Buffer capacity may not be negative");
57          }
58          this.buffer = new byte[capacity];
59      }
60  
61      private void expand(int newlen) {
62          byte newbuffer[] = new byte[Math.max(this.buffer.length << 1, newlen)];
63          System.arraycopy(this.buffer, 0, newbuffer, 0, this.len);
64          this.buffer = newbuffer;
65      }
66  
67      /**
68       * Appends <code>len</code> bytes to this buffer from the given source
69       * array starting at index <code>off</code>. The capacity of the buffer
70       * is increased, if necessary, to accommodate all <code>len</code> bytes.
71       *
72       * @param   b        the bytes to be appended.
73       * @param   off      the index of the first byte to append.
74       * @param   len      the number of bytes to append.
75       * @throws IndexOutOfBoundsException if <code>off</code> if out of
76       * range, <code>len</code> is negative, or
77       * <code>off</code> + <code>len</code> is out of range.
78       */
79      public void append(final byte[] b, int off, int len) {
80          if (b == null) {
81              return;
82          }
83          if ((off < 0) || (off > b.length) || (len < 0) ||
84                  ((off + len) < 0) || ((off + len) > b.length)) {
85              throw new IndexOutOfBoundsException("off: "+off+" len: "+len+" b.length: "+b.length);
86          }
87          if (len == 0) {
88              return;
89          }
90          int newlen = this.len + len;
91          if (newlen > this.buffer.length) {
92              expand(newlen);
93          }
94          System.arraycopy(b, off, this.buffer, this.len, len);
95          this.len = newlen;
96      }
97  
98      /**
99       * Appends <code>b</code> byte to this buffer. The capacity of the buffer
100      * is increased, if necessary, to accommodate the additional byte.
101      *
102      * @param   b        the byte to be appended.
103      */
104     public void append(int b) {
105         int newlen = this.len + 1;
106         if (newlen > this.buffer.length) {
107             expand(newlen);
108         }
109         this.buffer[this.len] = (byte)b;
110         this.len = newlen;
111     }
112 
113     /**
114      * Appends <code>len</code> chars to this buffer from the given source
115      * array starting at index <code>off</code>. The capacity of the buffer
116      * is increased if necessary to accommodate all <code>len</code> chars.
117      * <p>
118      * The chars are converted to bytes using simple cast.
119      *
120      * @param   b        the chars to be appended.
121      * @param   off      the index of the first char to append.
122      * @param   len      the number of bytes to append.
123      * @throws IndexOutOfBoundsException if <code>off</code> if out of
124      * range, <code>len</code> is negative, or
125      * <code>off</code> + <code>len</code> is out of range.
126      */
127     public void append(final char[] b, int off, int len) {
128         if (b == null) {
129             return;
130         }
131         if ((off < 0) || (off > b.length) || (len < 0) ||
132                 ((off + len) < 0) || ((off + len) > b.length)) {
133             throw new IndexOutOfBoundsException("off: "+off+" len: "+len+" b.length: "+b.length);
134         }
135         if (len == 0) {
136             return;
137         }
138         int oldlen = this.len;
139         int newlen = oldlen + len;
140         if (newlen > this.buffer.length) {
141             expand(newlen);
142         }
143         for (int i1 = off, i2 = oldlen; i2 < newlen; i1++, i2++) {
144             this.buffer[i2] = (byte) b[i1];
145         }
146         this.len = newlen;
147     }
148 
149     /**
150      * Appends <code>len</code> chars to this buffer from the given source
151      * char array buffer starting at index <code>off</code>. The capacity
152      * of the buffer is increased if necessary to accommodate all
153      * <code>len</code> chars.
154      * <p>
155      * The chars are converted to bytes using simple cast.
156      *
157      * @param   b        the chars to be appended.
158      * @param   off      the index of the first char to append.
159      * @param   len      the number of bytes to append.
160      * @throws IndexOutOfBoundsException if <code>off</code> if out of
161      * range, <code>len</code> is negative, or
162      * <code>off</code> + <code>len</code> is out of range.
163      */
164     public void append(final CharArrayBuffer b, int off, int len) {
165         if (b == null) {
166             return;
167         }
168         append(b.buffer(), off, len);
169     }
170 
171     /**
172      * Clears content of the buffer. The underlying byte array is not resized.
173      */
174     public void clear() {
175         this.len = 0;
176     }
177 
178     /**
179      * Converts the content of this buffer to an array of bytes.
180      *
181      * @return byte array
182      */
183     public byte[] toByteArray() {
184         byte[] b = new byte[this.len];
185         if (this.len > 0) {
186             System.arraycopy(this.buffer, 0, b, 0, this.len);
187         }
188         return b;
189     }
190 
191     /**
192      * Returns the <code>byte</code> value in this buffer at the specified
193      * index. The index argument must be greater than or equal to
194      * <code>0</code>, and less than the length of this buffer.
195      *
196      * @param      i   the index of the desired byte value.
197      * @return     the byte value at the specified index.
198      * @throws     IndexOutOfBoundsException  if <code>index</code> is
199      *             negative or greater than or equal to {@link #length()}.
200      */
201     public int byteAt(int i) {
202         return this.buffer[i];
203     }
204 
205     /**
206      * Returns the current capacity. The capacity is the amount of storage
207      * available for newly appended bytes, beyond which an allocation
208      * will occur.
209      *
210      * @return  the current capacity
211      */
212     public int capacity() {
213         return this.buffer.length;
214     }
215 
216     /**
217      * Returns the length of the buffer (byte count).
218      *
219      * @return  the length of the buffer
220      */
221     public int length() {
222         return this.len;
223     }
224 
225     /**
226      * Ensures that the capacity is at least equal to the specified minimum.
227      * If the current capacity is less than the argument, then a new internal
228      * array is allocated with greater capacity. If the <code>required</code>
229      * argument is non-positive, this method takes no action.
230      *
231      * @param   required   the minimum required capacity.
232      *
233      * @since 4.1
234      */
235     public void ensureCapacity(int required) {
236         if (required <= 0) {
237             return;
238         }
239         int available = this.buffer.length - this.len;
240         if (required > available) {
241             expand(this.len + required);
242         }
243     }
244 
245     /**
246      * Returns reference to the underlying byte array.
247      *
248      * @return the byte array.
249      */
250     public byte[] buffer() {
251         return this.buffer;
252     }
253 
254     /**
255      * Sets the length of the buffer. The new length value is expected to be
256      * less than the current capacity and greater than or equal to
257      * <code>0</code>.
258      *
259      * @param      len   the new length
260      * @throws     IndexOutOfBoundsException  if the
261      *               <code>len</code> argument is greater than the current
262      *               capacity of the buffer or less than <code>0</code>.
263      */
264     public void setLength(int len) {
265         if (len < 0 || len > this.buffer.length) {
266             throw new IndexOutOfBoundsException("len: "+len+" < 0 or > buffer len: "+this.buffer.length);
267         }
268         this.len = len;
269     }
270 
271     /**
272      * Returns <code>true</code> if this buffer is empty, that is, its
273      * {@link #length()} is equal to <code>0</code>.
274      * @return <code>true</code> if this buffer is empty, <code>false</code>
275      *   otherwise.
276      */
277     public boolean isEmpty() {
278         return this.len == 0;
279     }
280 
281     /**
282      * Returns <code>true</code> if this buffer is full, that is, its
283      * {@link #length()} is equal to its {@link #capacity()}.
284      * @return <code>true</code> if this buffer is full, <code>false</code>
285      *   otherwise.
286      */
287     public boolean isFull() {
288         return this.len == this.buffer.length;
289     }
290 
291     /**
292      * Returns the index within this buffer of the first occurrence of the
293      * specified byte, starting the search at the specified
294      * <code>beginIndex</code> and finishing at <code>endIndex</code>.
295      * If no such byte occurs in this buffer within the specified bounds,
296      * <code>-1</code> is returned.
297      * <p>
298      * There is no restriction on the value of <code>beginIndex</code> and
299      * <code>endIndex</code>. If <code>beginIndex</code> is negative,
300      * it has the same effect as if it were zero. If <code>endIndex</code> is
301      * greater than {@link #length()}, it has the same effect as if it were
302      * {@link #length()}. If the <code>beginIndex</code> is greater than
303      * the <code>endIndex</code>, <code>-1</code> is returned.
304      *
305      * @param   b            the byte to search for.
306      * @param   beginIndex   the index to start the search from.
307      * @param   endIndex     the index to finish the search at.
308      * @return  the index of the first occurrence of the byte in the buffer
309      *   within the given bounds, or <code>-1</code> if the byte does
310      *   not occur.
311      *
312      * @since 4.1
313      */
314     public int indexOf(byte b, int beginIndex, int endIndex) {
315         if (beginIndex < 0) {
316             beginIndex = 0;
317         }
318         if (endIndex > this.len) {
319             endIndex = this.len;
320         }
321         if (beginIndex > endIndex) {
322             return -1;
323         }
324         for (int i = beginIndex; i < endIndex; i++) {
325             if (this.buffer[i] == b) {
326                 return i;
327             }
328         }
329         return -1;
330     }
331 
332     /**
333      * Returns the index within this buffer of the first occurrence of the
334      * specified byte, starting the search at <code>0</code> and finishing
335      * at {@link #length()}. If no such byte occurs in this buffer within
336      * those bounds, <code>-1</code> is returned.
337      *
338      * @param   b   the byte to search for.
339      * @return  the index of the first occurrence of the byte in the
340      *   buffer, or <code>-1</code> if the byte does not occur.
341      *
342      * @since 4.1
343      */
344     public int indexOf(byte b) {
345         return indexOf(b, 0, this.len);
346     }
347 }