1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
|
/* StateStack.java
* =========================================================================
* This file is part of the GrInvIn project - http://www.grinvin.org
*
* Copyright (C) 2005-2008 Universiteit Gent
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* A copy of the GNU General Public License can be found in the file
* LICENSE.txt provided with the source distribution of this program (see
* the META-INF directory in the source jar). This license can also be
* found on the GNU website at http://www.gnu.org/licenses/gpl.html.
*
* If you did not receive a copy of the GNU General Public License along
* with this program, contact the lead developer, or write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
package org.grinvin.conjecture.engine.apengine;
/**
* Abstract class for handling state in the tree generators.
*/
public abstract class StateStack<E> {
//
private E[] contents;
//
protected int size;
// location of the top of the stack
protected int top;
/**
* Create a new StateStack.
*/
public StateStack() {
this(1);
}
/**
* Create a new StateStack.
* @param initSize the initial size of the stack
*/
private StateStack(int initSize) {
size = initSize;
contents = createArray(size);
// create stack objects once for the entire computation
for(int i=0; i < size;i++) {
contents[i] = emptyState();
}
top = 0;
}
//
protected abstract E emptyState();
//
protected abstract E[] createArray(int size);
/**
* Extend the size of the stack.
*/
protected void extend() {
int newSize = size*2;
E[] newContents = createArray(newSize);
System.arraycopy(contents, 0, newContents, 0, size);
for(int i=size; i < newSize;i++) {
newContents[i] = emptyState();
}
contents = newContents;
size = newSize;
}
//
public final E pop() {
top--;
if (top >= 0)
return contents[top];
else
return null;
}
//
public final E peek() {
if (top >= 0)
return contents[top];
else
return null;
}
//
public final boolean empty() {
return top == 0;
}
}
|
