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1
30
31 package org.jfree.util;
32
33 import java.io.Serializable  ;
34 import java.util.Arrays ;
35 import java.util.EmptyStackException ;
36
37
43 public final class FastStack implements Serializable , Cloneable
44 {
45 private Object [] contents;
46 private int size;
47 private int initialSize;
48
49 public FastStack()
50 {
51 initialSize = 10;
52 }
53
54 public FastStack(int size)
55 {
56 initialSize = Math.max(1, size);
57 }
58
59 public boolean isEmpty()
60 {
61 return size == 0;
62 }
63
64 public int size()
65 {
66 return size;
67 }
68
69 public void push(Object o)
70 {
71 if (contents == null)
72 {
73 contents = new Object [initialSize];
74 contents[0] = o;
75 size = 1;
76 return;
77 }
78
79 final int oldSize = size;
80 size += 1;
81 if (contents.length == size)
82 {
83 final Object [] newContents = new Object [size + initialSize];
85 System.arraycopy(contents, 0, newContents, 0, size);
86 this.contents = newContents;
87 }
88 this.contents[oldSize] = o;
89 }
90
91 public Object peek()
92 {
93 if (size == 0)
94 {
95 throw new EmptyStackException ();
96 }
97 return contents[size - 1];
98 }
99
100 public Object pop()
101 {
102 if (size == 0)
103 {
104 throw new EmptyStackException ();
105 }
106 size -= 1;
107 final Object retval = contents[size];
108 contents[size] = null;
109 return retval;
110 }
111
112 public Object clone()
113 {
114 try
115 {
116 FastStack stack = (FastStack) super.clone();
117 if (contents != null)
118 {
119 stack.contents = (Object []) contents.clone();
120 }
121 return stack;
122 }
123 catch (CloneNotSupportedException cne)
124 {
125 throw new IllegalStateException ("Clone not supported? Why?");
126 }
127 }
128
129 public void clear()
130 {
131 size = 0;
132 if (contents != null)
133 {
134 Arrays.fill(contents, null);
135 }
136 }
137
138 public Object get(final int index)
139 {
140 if (index >= size)
141 {
142 throw new IndexOutOfBoundsException ();
143 }
144 return contents[index];
145 }
146 }
147 |
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