src/jdk/internal/dynalink/beans/MaximallySpecific.java

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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
84 package jdk.internal.dynalink.beans;
85
86 import java.lang.invoke.MethodHandle;
87 import java.lang.invoke.MethodType;
88 import java.util.Iterator;
89 import java.util.LinkedList;
90 import java.util.List;
91 import jdk.internal.dynalink.linker.ConversionComparator.Comparison;
92 import jdk.internal.dynalink.linker.LinkerServices;
93 import jdk.internal.dynalink.support.TypeUtilities;
94
95 /**
96 * Utility class that encapsulates the algorithm for choosing the maximally specific methods.
97 *
98 * @author Attila Szegedi
99 */
100 class MaximallySpecific {
101 /**
102 * Given a list of methods, returns a list of maximally specific methods.
103 *
104 * @param methods the list of methods
105 * @param varArgs whether to assume the methods are varargs
106 * @return the list of maximally specific methods.
107 */
108 static List<SingleDynamicMethod> getMaximallySpecificMethods(List<SingleDynamicMethod> methods, boolean varArgs) {
109 return getMaximallySpecificSingleDynamicMethods(methods, varArgs, null, null);
110 }
111
112 private abstract static class MethodTypeGetter<T> {
113 abstract MethodType getMethodType(T t);
114 }
115
116 private static final MethodTypeGetter<MethodHandle> METHOD_HANDLE_TYPE_GETTER =
117 new MethodTypeGetter<MethodHandle>() {
118 @Override
119 MethodType getMethodType(MethodHandle t) {
120 return t.type();
121 }
122 };
123
124 private static final MethodTypeGetter<SingleDynamicMethod> DYNAMIC_METHOD_TYPE_GETTER =
125 new MethodTypeGetter<SingleDynamicMethod>() {
126 @Override
127 MethodType getMethodType(SingleDynamicMethod t) {
128 return t.getMethodType();
129 }
130 };
131
132 /**
133 * Given a list of methods handles, returns a list of maximally specific methods, applying language-runtime
134 * specific conversion preferences.
135 *
136 * @param methods the list of method handles
137 * @param varArgs whether to assume the method handles are varargs
138 * @param argTypes concrete argument types for the invocation
139 * @return the list of maximally specific method handles.
140 */
141 static List<MethodHandle> getMaximallySpecificMethodHandles(List<MethodHandle> methods, boolean varArgs,
142 Class<?>[] argTypes, LinkerServices ls) {
143 return getMaximallySpecificMethods(methods, varArgs, argTypes, ls, METHOD_HANDLE_TYPE_GETTER);
144 }
145
146 /**
147 * Given a list of methods, returns a list of maximally specific methods, applying language-runtime specific
148 * conversion preferences.
149 *
150 * @param methods the list of methods
151 * @param varArgs whether to assume the methods are varargs
152 * @param argTypes concrete argument types for the invocation
153 * @return the list of maximally specific methods.
154 */
155 static List<SingleDynamicMethod> getMaximallySpecificSingleDynamicMethods(List<SingleDynamicMethod> methods,
156 boolean varArgs, Class<?>[] argTypes, LinkerServices ls) {
157 return getMaximallySpecificMethods(methods, varArgs, argTypes, ls, DYNAMIC_METHOD_TYPE_GETTER);
158 }
159
160 /**
161 * Given a list of methods, returns a list of maximally specific methods, applying language-runtime specific
162 * conversion preferences.
163 *
164 * @param methods the list of methods
165 * @param varArgs whether to assume the methods are varargs
166 * @param argTypes concrete argument types for the invocation
167 * @return the list of maximally specific methods.
168 */
169 private static <T> List<T> getMaximallySpecificMethods(List<T> methods, boolean varArgs,
170 Class<?>[] argTypes, LinkerServices ls, MethodTypeGetter<T> methodTypeGetter) {
171 if(methods.size() < 2) {
172 return methods;
173 }
174 final LinkedList<T> maximals = new LinkedList<>();
175 for(T m: methods) {
176 final MethodType methodType = methodTypeGetter.getMethodType(m);
177 boolean lessSpecific = false;
178 for(Iterator<T> maximal = maximals.iterator(); maximal.hasNext();) {
179 final T max = maximal.next();
180 switch(isMoreSpecific(methodType, methodTypeGetter.getMethodType(max), varArgs, argTypes, ls)) {
181 case TYPE_1_BETTER: {
182 maximal.remove();
183 break;
184 }
185 case TYPE_2_BETTER: {
186 lessSpecific = true;
187 break;
188 }
189 case INDETERMINATE: {
190 // do nothing
191 break;
192 }
193 default: {
194 throw new AssertionError();
195 }
196 }
197 }
198 if(!lessSpecific) {
199 maximals.addLast(m);
200 }
201 }
202 return maximals;
203 }
204
205 private static Comparison isMoreSpecific(MethodType t1, MethodType t2, boolean varArgs, Class<?>[] argTypes,
206 LinkerServices ls) {
207 final int pc1 = t1.parameterCount();
208 final int pc2 = t2.parameterCount();
209 assert varArgs || (pc1 == pc2) && (argTypes == null || argTypes.length == pc1);
210 assert (argTypes == null) == (ls == null);
211 final int maxPc = Math.max(Math.max(pc1, pc2), argTypes == null ? 0 : argTypes.length);
212 boolean t1MoreSpecific = false;
213 boolean t2MoreSpecific = false;
214 // NOTE: Starting from 1 as overloaded method resolution doesn't depend on 0th element, which is the type of
215 // 'this'. We're only dealing with instance methods here, not static methods. Actually, static methods will have
216 // a fake 'this' of type StaticClass.
217 for(int i = 1; i < maxPc; ++i) {
218 final Class<?> c1 = getParameterClass(t1, pc1, i, varArgs);
219 final Class<?> c2 = getParameterClass(t2, pc2, i, varArgs);
220 if(c1 != c2) {
221 final Comparison cmp = compare(c1, c2, argTypes, i, ls);
222 if(cmp == Comparison.TYPE_1_BETTER && !t1MoreSpecific) {
223 t1MoreSpecific = true;
224 if(t2MoreSpecific) {
225 return Comparison.INDETERMINATE;
226 }
227 }
228 if(cmp == Comparison.TYPE_2_BETTER && !t2MoreSpecific) {
229 t2MoreSpecific = true;
230 if(t1MoreSpecific) {
231 return Comparison.INDETERMINATE;
232 }
233 }
234 }
235 }
236 if(t1MoreSpecific) {
237 return Comparison.TYPE_1_BETTER;
238 } else if(t2MoreSpecific) {
239 return Comparison.TYPE_2_BETTER;
240 }
241 return Comparison.INDETERMINATE;
242 }
243
244 private static Comparison compare(Class<?> c1, Class<?> c2, Class<?>[] argTypes, int i, LinkerServices cmp) {
245 if(cmp != null) {
246 final Comparison c = cmp.compareConversion(argTypes[i], c1, c2);
247 if(c != Comparison.INDETERMINATE) {
248 return c;
249 }
250 }
251 if(TypeUtilities.isSubtype(c1, c2)) {
252 return Comparison.TYPE_1_BETTER;
253 } if(TypeUtilities.isSubtype(c2, c1)) {
254 return Comparison.TYPE_2_BETTER;
255 }
256 return Comparison.INDETERMINATE;
257 }
258
259 private static Class<?> getParameterClass(MethodType t, int l, int i, boolean varArgs) {
260 return varArgs && i >= l - 1 ? t.parameterType(l - 1).getComponentType() : t.parameterType(i);
261 }
262 }

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