1 /*
2 * Copyright (c) 2008, 2018, 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
1066 * Adapts this method handle to be {@linkplain #asVarargsCollector variable arity}
1067 * if the boolean flag is true, else {@linkplain #asFixedArity fixed arity}.
1068 * If the method handle is already of the proper arity mode, it is returned
1069 * unchanged.
1070 * @apiNote
1071 * <p>This method is sometimes useful when adapting a method handle that
1072 * may be variable arity, to ensure that the resulting adapter is also
1073 * variable arity if and only if the original handle was. For example,
1074 * this code changes the first argument of a handle {@code mh} to {@code int} without
1075 * disturbing its variable arity property:
1076 * {@code mh.asType(mh.type().changeParameterType(0,int.class))
1077 * .withVarargs(mh.isVarargsCollector())}
1078 * <p>
1079 * This call is approximately equivalent to the following code:
1080 * <blockquote><pre>{@code
1081 * if (makeVarargs == isVarargsCollector())
1082 * return this;
1083 * else if (makeVarargs)
1084 * return asVarargsCollector(type().lastParameterType());
1085 * else
1086 * return return asFixedArity();
1087 * }</pre></blockquote>
1088 * @param makeVarargs true if the return method handle should have variable arity behavior
1089 * @return a method handle of the same type, with possibly adjusted variable arity behavior
1090 * @throws IllegalArgumentException if {@code makeVarargs} is true and
1091 * this method handle does not have a trailing array parameter
1092 * @since 9
1093 * @see #asVarargsCollector
1094 * @see #asFixedArity
1095 */
1096 public MethodHandle withVarargs(boolean makeVarargs) {
1097 assert(!isVarargsCollector()); // subclass responsibility
1098 if (makeVarargs) {
1099 return asVarargsCollector(type().lastParameterType());
1100 } else {
1101 return this;
1102 }
1103 }
1104
1105 /**
1106 * Makes an <em>array-collecting</em> method handle, which accepts a given number of trailing
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1 /*
2 * Copyright (c) 2008, 2019, 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
1066 * Adapts this method handle to be {@linkplain #asVarargsCollector variable arity}
1067 * if the boolean flag is true, else {@linkplain #asFixedArity fixed arity}.
1068 * If the method handle is already of the proper arity mode, it is returned
1069 * unchanged.
1070 * @apiNote
1071 * <p>This method is sometimes useful when adapting a method handle that
1072 * may be variable arity, to ensure that the resulting adapter is also
1073 * variable arity if and only if the original handle was. For example,
1074 * this code changes the first argument of a handle {@code mh} to {@code int} without
1075 * disturbing its variable arity property:
1076 * {@code mh.asType(mh.type().changeParameterType(0,int.class))
1077 * .withVarargs(mh.isVarargsCollector())}
1078 * <p>
1079 * This call is approximately equivalent to the following code:
1080 * <blockquote><pre>{@code
1081 * if (makeVarargs == isVarargsCollector())
1082 * return this;
1083 * else if (makeVarargs)
1084 * return asVarargsCollector(type().lastParameterType());
1085 * else
1086 * return asFixedArity();
1087 * }</pre></blockquote>
1088 * @param makeVarargs true if the return method handle should have variable arity behavior
1089 * @return a method handle of the same type, with possibly adjusted variable arity behavior
1090 * @throws IllegalArgumentException if {@code makeVarargs} is true and
1091 * this method handle does not have a trailing array parameter
1092 * @since 9
1093 * @see #asVarargsCollector
1094 * @see #asFixedArity
1095 */
1096 public MethodHandle withVarargs(boolean makeVarargs) {
1097 assert(!isVarargsCollector()); // subclass responsibility
1098 if (makeVarargs) {
1099 return asVarargsCollector(type().lastParameterType());
1100 } else {
1101 return this;
1102 }
1103 }
1104
1105 /**
1106 * Makes an <em>array-collecting</em> method handle, which accepts a given number of trailing
|