1/*
2 * Copyright (c) 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package java.lang.module;
27
28import java.util.Objects;
29import java.util.Set;
30
31/**
32 * A module in a graph of <em>resolved modules</em>.
33 *
34 * <p> {@code ResolvedModule} defines the {@link #configuration configuration}
35 * method to get the configuration that the resolved module is in. It defines
36 * the {@link #reference() reference} method to get the reference to the
37 * module's content.
38 *
39 * @since 9
40 * @spec JPMS
41 * @see Configuration#modules()
42 */
43public final class ResolvedModule {
44
45    private final Configuration cf;
46    private final ModuleReference mref;
47
48    ResolvedModule(Configuration cf, ModuleReference mref) {
49        this.cf = Objects.requireNonNull(cf);
50        this.mref = Objects.requireNonNull(mref);
51    }
52
53    /**
54     * Returns the configuration that this resolved module is in.
55     *
56     * @return The configuration that this resolved module is in
57     */
58    public Configuration configuration() {
59        return cf;
60    }
61
62    /**
63     * Returns the reference to the module's content.
64     *
65     * @return The reference to the module's content
66     */
67    public ModuleReference reference() {
68        return mref;
69    }
70
71    /**
72     * Returns the module descriptor.
73     *
74     * This convenience method is the equivalent to invoking:
75     * <pre> {@code
76     *     reference().descriptor()
77     * }</pre>
78     *
79     * @return The module descriptor
80     */
81    ModuleDescriptor descriptor() {
82        return reference().descriptor();
83    }
84
85    /**
86     * Returns the module name.
87     *
88     * This convenience method is the equivalent to invoking:
89     * <pre> {@code
90     *     reference().descriptor().name()
91     * }</pre>
92     *
93     * @return The module name
94     */
95    public String name() {
96        return reference().descriptor().name();
97    }
98
99    /**
100     * Returns the set of resolved modules that this resolved module reads.
101     *
102     * @return A possibly-empty unmodifiable set of resolved modules that
103     *         this resolved module reads
104     */
105    public Set<ResolvedModule> reads() {
106        return cf.reads(this);
107    }
108
109    /**
110     * Computes a hash code for this resolved module.
111     *
112     * <p> The hash code is based upon the components of the resolved module
113     * and satisfies the general contract of the {@link Object#hashCode
114     * Object.hashCode} method. </p>
115     *
116     * @return The hash-code value for this resolved module
117     */
118    @Override
119    public int hashCode() {
120        return cf.hashCode() ^ mref.hashCode();
121    }
122
123    /**
124     * Tests this resolved module for equality with the given object.
125     *
126     * <p> If the given object is not a {@code ResolvedModule} then this
127     * method returns {@code false}. Two {@code ResolvedModule} objects are
128     * equal if they are in the same configuration and have equal references
129     * to the module content. </p>
130     *
131     * <p> This method satisfies the general contract of the {@link
132     * java.lang.Object#equals(Object) Object.equals} method. </p>
133     *
134     * @param   ob
135     *          the object to which this object is to be compared
136     *
137     * @return  {@code true} if, and only if, the given object is a module
138     *          reference that is equal to this module reference
139     */
140    @Override
141    public boolean equals(Object ob) {
142        if (!(ob instanceof ResolvedModule))
143            return false;
144
145        ResolvedModule that = (ResolvedModule) ob;
146        return Objects.equals(this.cf, that.cf)
147                && Objects.equals(this.mref, that.mref);
148    }
149
150    /**
151     * Returns a string describing this resolved module.
152     *
153     * @return A string describing this resolved module
154     */
155    @Override
156    public String toString() {
157        return System.identityHashCode(cf) + "/" + name();
158    }
159
160}
161