1/*
2 * Copyright (c) 2010, 2013, 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
26/*
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file, and Oracle licenses the original version of this file under the BSD
31 * license:
32 */
33/*
34   Copyright 2009-2013 Attila Szegedi
35
36   Licensed under both the Apache License, Version 2.0 (the "Apache License")
37   and the BSD License (the "BSD License"), with licensee being free to
38   choose either of the two at their discretion.
39
40   You may not use this file except in compliance with either the Apache
41   License or the BSD License.
42
43   If you choose to use this file in compliance with the Apache License, the
44   following notice applies to you:
45
46       You may obtain a copy of the Apache License at
47
48           http://www.apache.org/licenses/LICENSE-2.0
49
50       Unless required by applicable law or agreed to in writing, software
51       distributed under the License is distributed on an "AS IS" BASIS,
52       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
53       implied. See the License for the specific language governing
54       permissions and limitations under the License.
55
56   If you choose to use this file in compliance with the BSD License, the
57   following notice applies to you:
58
59       Redistribution and use in source and binary forms, with or without
60       modification, are permitted provided that the following conditions are
61       met:
62       * Redistributions of source code must retain the above copyright
63         notice, this list of conditions and the following disclaimer.
64       * Redistributions in binary form must reproduce the above copyright
65         notice, this list of conditions and the following disclaimer in the
66         documentation and/or other materials provided with the distribution.
67       * Neither the name of the copyright holder nor the names of
68         contributors may be used to endorse or promote products derived from
69         this software without specific prior written permission.
70
71       THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
72       IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
73       TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
74       PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER
75       BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
76       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
77       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
78       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
79       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
80       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
81       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
82*/
83
84package jdk.dynalink.beans;
85
86import java.lang.invoke.MethodHandle;
87import java.lang.invoke.MethodType;
88import java.security.AccessControlContext;
89import java.security.AccessController;
90import java.security.PrivilegedAction;
91import java.util.Arrays;
92import java.util.LinkedList;
93import java.util.List;
94import jdk.dynalink.internal.AccessControlContextFactory;
95import jdk.dynalink.internal.InternalTypeUtilities;
96import jdk.dynalink.linker.LinkerServices;
97import jdk.dynalink.linker.support.TypeUtilities;
98
99/**
100 * Represents a sequence of {@link Class} objects, useful for representing method signatures. Provides value
101 * semantics for using them as map keys, as well as specificity calculations and applicability checks as per
102 * JLS.
103 */
104final class ClassString {
105    private static final AccessControlContext GET_CLASS_LOADER_CONTEXT =
106            AccessControlContextFactory.createAccessControlContext("getClassLoader");
107
108    /**
109     * An anonymous inner class used solely to represent the "type" of null values for method applicability checking.
110     */
111    static final Class<?> NULL_CLASS = (new Object() { /* Intentionally empty */ }).getClass();
112
113    private final Class<?>[] classes;
114    private int hashCode;
115
116    ClassString(final Class<?>[] classes) {
117        this.classes = classes;
118    }
119
120    ClassString(final MethodType type) {
121        this(type.parameterArray());
122    }
123
124    @Override
125    public boolean equals(final Object other) {
126        if(!(other instanceof ClassString)) {
127            return false;
128        }
129        final Class<?>[] otherClasses = ((ClassString)other).classes;
130        if(otherClasses.length != classes.length) {
131            return false;
132        }
133        for(int i = 0; i < otherClasses.length; ++i) {
134            if(otherClasses[i] != classes[i]) {
135                return false;
136            }
137        }
138        return true;
139    }
140
141    @Override
142    public int hashCode() {
143        if(hashCode == 0) {
144            int h = 0;
145            for(int i = 0; i < classes.length; ++i) {
146                h ^= classes[i].hashCode();
147            }
148            hashCode = h;
149        }
150        return hashCode;
151    }
152
153    @Override
154    public String toString() {
155        return "ClassString[" + Arrays.toString(classes) + "]";
156    }
157
158    boolean isVisibleFrom(final ClassLoader classLoader) {
159        return AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
160            @Override
161            public Boolean run() {
162                for(final Class<?> clazz: classes) {
163                    if(!InternalTypeUtilities.canReferenceDirectly(classLoader, clazz.getClassLoader())) {
164                        return false;
165                    }
166                }
167                return true;
168            }
169        }, GET_CLASS_LOADER_CONTEXT);
170    }
171
172    List<MethodHandle> getMaximallySpecifics(final List<MethodHandle> methods, final LinkerServices linkerServices, final boolean varArg) {
173        return MaximallySpecific.getMaximallySpecificMethodHandles(getApplicables(methods, linkerServices, varArg),
174                varArg, classes, linkerServices);
175    }
176
177    /**
178     * Returns all methods that are applicable to actual parameter classes represented by this ClassString object.
179     */
180    LinkedList<MethodHandle> getApplicables(final List<MethodHandle> methods, final LinkerServices linkerServices, final boolean varArg) {
181        final LinkedList<MethodHandle> list = new LinkedList<>();
182        for(final MethodHandle member: methods) {
183            if(isApplicable(member, linkerServices, varArg)) {
184                list.add(member);
185            }
186        }
187        return list;
188    }
189
190    /**
191     * Returns true if the supplied method is applicable to actual parameter classes represented by this ClassString
192     * object.
193     *
194     */
195    private boolean isApplicable(final MethodHandle method, final LinkerServices linkerServices, final boolean varArg) {
196        final Class<?>[] formalTypes = method.type().parameterArray();
197        final int cl = classes.length;
198        final int fl = formalTypes.length - (varArg ? 1 : 0);
199        if(varArg) {
200            if(cl < fl) {
201                return false;
202            }
203        } else {
204            if(cl != fl) {
205                return false;
206            }
207        }
208        // Starting from 1 as we ignore the receiver type
209        for(int i = 1; i < fl; ++i) {
210            if(!canConvert(linkerServices, classes[i], formalTypes[i])) {
211                return false;
212            }
213        }
214        if(varArg) {
215            final Class<?> varArgType = formalTypes[fl].getComponentType();
216            for(int i = fl; i < cl; ++i) {
217                if(!canConvert(linkerServices, classes[i], varArgType)) {
218                    return false;
219                }
220            }
221        }
222        return true;
223    }
224
225    private static boolean canConvert(final LinkerServices ls, final Class<?> from, final Class<?> to) {
226        if(from == NULL_CLASS) {
227            return !to.isPrimitive();
228        }
229        return ls == null ? TypeUtilities.isMethodInvocationConvertible(from, to) : ls.canConvert(from, to);
230    }
231}
232