CstKnownNull.java revision 579d7739c53a2707ad711a2d2cae46d7d782f061 
1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.dx.rop.cst;
18
19import com.android.dx.rop.type.Type;
20
21/**
22 * Constant type to represent a known-{@code null} value.
23 */
24public final class CstKnownNull extends CstLiteralBits {
25    /** {@code non-null;} unique instance of this class */
26    public static final CstKnownNull THE_ONE = new CstKnownNull();
27
28    /**
29     * Constructs an instance. This class is not publicly instantiable. Use
30     * {@link #THE_ONE}.
31     */
32    private CstKnownNull() {
33        // This space intentionally left blank.
34    }
35
36    /** {@inheritDoc} */
37    @Override
38    public boolean equals(Object other) {
39        return (other instanceof CstKnownNull);
40    }
41
42    /** {@inheritDoc} */
43    @Override
44    public int hashCode() {
45        return 0x4466757a;
46    }
47
48    /** {@inheritDoc} */
49    @Override
50    protected int compareTo0(Constant other) {
51        return 0;
52    }
53
54    /** {@inheritDoc} */
55    @Override
56    public String toString() {
57        return "known-null";
58    }
59
60    /** {@inheritDoc} */
61    public Type getType() {
62        return Type.KNOWN_NULL;
63    }
64
65    /** {@inheritDoc} */
66    @Override
67    public String typeName() {
68        return "known-null";
69    }
70
71    /** {@inheritDoc} */
72    @Override
73    public boolean isCategory2() {
74        return false;
75    }
76
77    /** {@inheritDoc} */
78    public String toHuman() {
79        return "null";
80    }
81
82    /** {@inheritDoc} */
83    @Override
84    public boolean fitsInInt() {
85        // See comment in getIntBits().
86        return true;
87    }
88
89    /**
90     * {@inheritDoc}
91     *
92     * As "literal bits," a known-null is always represented as the
93     * number zero.
94     */
95    @Override
96    public int getIntBits() {
97        return 0;
98    }
99
100    /**
101     * {@inheritDoc}
102     *
103     * As "literal bits," a known-null is always represented as the
104     * number zero.
105     */
106    @Override
107    public long getLongBits() {
108        return 0;
109    }
110}
111