1/*
2 * Copyright (c) 2009, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23package jdk.vm.ci.meta;
24
25/**
26 * Abstract base class for values.
27 */
28public abstract class Value {
29
30    public static final Value[] NO_VALUES = new Value[0];
31
32    public static final AllocatableValue ILLEGAL = new IllegalValue();
33
34    private static final class IllegalValue extends AllocatableValue {
35        private IllegalValue() {
36            super(ValueKind.Illegal);
37        }
38
39        @Override
40        public String toString() {
41            return "-";
42        }
43
44        @Override
45        public boolean equals(Object other) {
46            // Due to de-serialization this object may exist multiple times. So we compare classes
47            // instead of the individual objects. (This anonymous class has always the same meaning)
48            return other instanceof IllegalValue;
49        }
50    }
51
52    private final ValueKind<?> valueKind;
53
54    /**
55     * Initializes a new value of the specified kind.
56     *
57     * @param valueKind the kind
58     */
59    protected Value(ValueKind<?> valueKind) {
60        this.valueKind = valueKind;
61    }
62
63    /**
64     * Returns a String representation of the kind, which should be the end of all
65     * {@link #toString()} implementation of subclasses.
66     */
67    protected final String getKindSuffix() {
68        return "|" + valueKind.getKindSuffix();
69    }
70
71    public final ValueKind<?> getValueKind() {
72        return valueKind;
73    }
74
75    public final <K extends ValueKind<K>> K getValueKind(Class<K> cls) {
76        return cls.cast(valueKind);
77    }
78
79    /**
80     * Returns the platform specific kind used to store this value.
81     */
82    public final PlatformKind getPlatformKind() {
83        return valueKind.getPlatformKind();
84    }
85
86    @Override
87    public int hashCode() {
88        return 41 + valueKind.hashCode();
89    }
90
91    @Override
92    public boolean equals(Object obj) {
93        if (obj instanceof Value) {
94            Value that = (Value) obj;
95            return valueKind.equals(that.valueKind);
96        }
97        return false;
98    }
99
100    /**
101     * Checks if this value is identical to {@code other}.
102     *
103     * Warning: Use with caution! Usually equivalence {@link #equals(Object)} is sufficient and
104     * should be used.
105     */
106    public final boolean identityEquals(Value other) {
107        return this == other;
108    }
109}
110