1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.bcel.verifier.structurals;
18
19 /**
20 * This class represents a JVM execution frame; that means, a local variable array and an operand stack.
21 */
22
23 public class Frame {
24
25 /**
26 * For instance initialization methods, it is important to remember which instance it is that is not initialized yet. It
27 * will be initialized invoking another constructor later. NULL means the instance already *is* initialized.
28 *
29 * @deprecated Use the getter/setter to access the field as it may be made private in a later release
30 */
31 @Deprecated
32 protected static UninitializedObjectType _this;
33
34 /**
35 * @return the _this
36 * @since 6.0
37 */
38 public static UninitializedObjectType getThis() {
39 return _this;
40 }
41
42 /**
43 * @param _this the _this to set
44 * @since 6.0
45 */
46 public static void setThis(final UninitializedObjectType _this) {
47 Frame._this = _this;
48 }
49
50 /**
51 */
52 private final LocalVariables locals;
53
54 /**
55 */
56 private final OperandStack stack;
57
58 /**
59 */
60 public Frame(final int maxLocals, final int maxStack) {
61 locals = new LocalVariables(maxLocals);
62 stack = new OperandStack(maxStack);
63 }
64
65 /**
66 */
67 public Frame(final LocalVariables locals, final OperandStack stack) {
68 this.locals = locals;
69 this.stack = stack;
70 }
71
72 /**
73 */
74 @Override
75 protected Object clone() {
76 return new Frame(locals.getClone(), stack.getClone());
77 }
78
79 /**
80 */
81 @Override
82 public boolean equals(final Object o) {
83 if (!(o instanceof Frame)) {
84 return false; // implies "null" is non-equal.
85 }
86 final Frame f = (Frame) o;
87 return this.stack.equals(f.stack) && this.locals.equals(f.locals);
88 }
89
90 /**
91 */
92 public Frame getClone() {
93 return (Frame) clone();
94 }
95
96 /**
97 */
98 public LocalVariables getLocals() {
99 return locals;
100 }
101
102 /**
103 */
104 public OperandStack getStack() {
105 return stack;
106 }
107
108 /**
109 * @return a hash code value for the object.
110 */
111 @Override
112 public int hashCode() {
113 return stack.hashCode() ^ locals.hashCode();
114 }
115
116 /**
117 * Returns a String representation of the Frame instance.
118 */
119 @Override
120 public String toString() {
121 StringBuilder s = new StringBuilder("Local Variables:\n");
122 s.append(locals);
123 s.append("OperandStack:\n");
124 s.append(stack);
125 return s.toString();
126 }
127 }