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1
50 package org.apache.avalon.excalibur.collections;
51
52
59 public class CircularBuffer
60 {
61 protected Object  [] m_buffer;
62 protected int m_bufferSize;
63 protected int m_contentSize;
64 protected int m_head;
65 protected int m_tail;
66
67 public CircularBuffer( int size )
68 {
69 m_buffer = new Object [ size ];
70 m_bufferSize = size;
71 m_contentSize = 0;
72 m_head = 0;
73 m_tail = 0;
74 }
75
76 public CircularBuffer()
77 {
78 this( 32 );
79 }
80
81 public boolean isEmpty()
82 {
83 return ( m_contentSize == 0 );
84 }
85
86 public int getContentSize()
87 {
88 return m_contentSize;
89 }
90
91 public int getBufferSize()
92 {
93 return m_bufferSize;
94 }
95
96 public void append( final Object o )
97 {
98 if( m_contentSize >= m_bufferSize )
99 {
100 int j = 0;
101 int i = m_tail;
102 Object [] tmp = new Object [ m_bufferSize * 2 ];
103
104 while( m_contentSize > 0 )
105 {
106 i++;
107 i %= m_bufferSize;
108 j++;
109 m_contentSize--;
110 tmp[ j ] = m_buffer[ i ];
111 }
112 m_buffer = tmp;
113 m_tail = 0;
114 m_head = j;
115 m_contentSize = j;
116 m_bufferSize *= 2;
117 }
118
119 m_buffer[ m_head ] = o;
120 m_head++;
121 m_head %= m_bufferSize;
122 m_contentSize++;
123 }
124
125 public Object get()
126 {
127 if( m_contentSize <= 0 )
128 {
129 return null;
130 }
131
132 Object o = m_buffer[ m_tail ];
133 m_tail++;
134 m_tail %= m_bufferSize;
135 m_contentSize--;
136 return o;
137 }
138 }
139
140
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