Clover Coverage Report
Coverage timestamp: Fri May 9 2008 10:54:27 EST
Overview   Package   File
    FRAMES   NO FRAMES     
../../../../img/srcFileCovDistChart10.png 0% of files have more coverage
28   136   10   3.5
4   77   0.36   8
8     1.25  
1    
 
  BitVector       Line # 36 28 10 100% 1.0
 
  (24)
 
1    package org.apache.lucene.util;
2   
3    /**
4    * Copyright 2004 The Apache Software Foundation
5    *
6    * Licensed under the Apache License, Version 2.0 (the "License");
7    * you may not use this file except in compliance with the License.
8    * You may obtain a copy of the License at
9    *
10    * http://www.apache.org/licenses/LICENSE-2.0
11    *
12    * Unless required by applicable law or agreed to in writing, software
13    * distributed under the License is distributed on an "AS IS" BASIS,
14    * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15    * See the License for the specific language governing permissions and
16    * limitations under the License.
17    */
18   
19    import java.io.IOException;
20   
21    import org.apache.lucene.store.Directory;
22    import org.apache.lucene.store.IndexInput;
23    import org.apache.lucene.store.IndexOutput;
24   
25    /** Optimized implementation of a vector of bits. This is more-or-less like
26    java.util.BitSet, but also includes the following:
27    <ul>
28    <li>a count() method, which efficiently computes the number of one bits;</li>
29    <li>optimized read from and write to disk;</li>
30    <li>inlinable get() method;</li>
31    </ul>
32   
33    @author Doug Cutting
34    @version $Id: BitVector.java 150536 2004-09-28 18:15:52Z cutting $
35    */
 
36    public final class BitVector {
37   
38    private byte[] bits;
39    private int size;
40    private int count = -1;
41   
42    /** Constructs a vector capable of holding <code>n</code> bits. */
 
43  837 toggle public BitVector(int n) {
44  837 size = n;
45  837 bits = new byte[(size >> 3) + 1];
46    }
47   
48    /** Sets the value of <code>bit</code> to one. */
 
49  7982 toggle public final void set(int bit) {
50  7982 bits[bit >> 3] |= 1 << (bit & 7);
51  7982 count = -1;
52    }
53   
54    /** Sets the value of <code>bit</code> to zero. */
 
55  2256 toggle public final void clear(int bit) {
56  2256 bits[bit >> 3] &= ~(1 << (bit & 7));
57  2256 count = -1;
58    }
59   
60    /** Returns <code>true</code> if <code>bit</code> is one and
61    <code>false</code> if it is zero. */
 
62  2098140 toggle public final boolean get(int bit) {
63  2098140 return (bits[bit >> 3] & (1 << (bit & 7))) != 0;
64    }
65   
66    /** Returns the number of bits in this vector. This is also one greater than
67    the number of the largest valid bit number. */
 
68  1019369 toggle public final int size() {
69  1019369 return size;
70    }
71   
72    /** Returns the total number of one bits in this vector. This is efficiently
73    computed and cached, so that, if the vector is not changed, no
74    recomputation is done for repeated calls. */
 
75  10825 toggle public final int count() {
76    // if the vector has been modified
77  10825 if (count == -1) {
78  5511 int c = 0;
79  5511 int end = bits.length;
80  517505 for (int i = 0; i < end; i++)
81  511994 c += BYTE_COUNTS[bits[i] & 0xFF]; // sum bits per byte
82  5511 count = c;
83    }
84  10825 return count;
85    }
86   
87    private static final byte[] BYTE_COUNTS = { // table of bits/byte
88    0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
89    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
90    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
91    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
92    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
93    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
94    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
95    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
96    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
97    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
98    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
99    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
100    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
101    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
102    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
103    4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
104    };
105   
106   
107    /** Writes this vector to the file <code>name</code> in Directory
108    <code>d</code>, in a format that can be read by the constructor {@link
109    #BitVector(Directory, String)}. */
 
110  2113 toggle public final void write(Directory d, String name) throws IOException {
111  2113 IndexOutput output = d.createOutput(name);
112  2113 try {
113  2113 output.writeInt(size()); // write size
114  2113 output.writeInt(count()); // write count
115  2113 output.writeBytes(bits, bits.length); // write bits
116    } finally {
117  2113 output.close();
118    }
119    }
120   
121    /** Constructs a bit vector from the file <code>name</code> in Directory
122    <code>d</code>, as written by the {@link #write} method.
123