1 /*

     2  * Copyright (c) 2008, 2010, 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 package sun.dyn;

    27 

    28 import java.dyn.*;

    29 import static sun.dyn.MemberName.uncaughtException;

    30 

    31 /**

    32  * Unary function composition, useful for many small plumbing jobs.

    33  * The invoke method takes a single reference argument, and returns a reference

    34  * Internally, it first calls the {@code filter} method on the argument,

    35  * Making up the difference between the raw method type and the

    36  * final method type is the responsibility of a JVM-level adapter.

    37  * @author jrose

    38  */

    39 public class FilterOneArgument extends BoundMethodHandle {

    40     protected final MethodHandle filter;  // Object -> Object

    41     protected final MethodHandle target;  // Object -> Object

    42 

    43     @Override

    44     public String toString() {

    45         return target.toString();

    46     }

    47 

    48     protected Object invoke(Object argument) throws Throwable {

    49         Object filteredArgument = filter.invokeExact(argument);

    50         return target.invokeExact(filteredArgument);

    51     }

    52 

    53     private static final MethodHandle INVOKE;

    54     static {

    55         try {

    56             INVOKE =

    57                 MethodHandleImpl.IMPL_LOOKUP.findVirtual(FilterOneArgument.class, "invoke",

    58                                                          MethodType.genericMethodType(1));

    59         } catch (ReflectiveOperationException ex) {

    60             throw uncaughtException(ex);

    61         }

    62     }

    63 

    64     protected FilterOneArgument(MethodHandle filter, MethodHandle target) {

    65         super(Access.TOKEN, INVOKE);

    66         this.filter = filter;

    67         this.target = target;

    68     }

    69 

    70     public static MethodHandle make(MethodHandle filter, MethodHandle target) {

    71         if (filter == null)  return target;

    72         if (target == null)  return filter;

    73         return new FilterOneArgument(filter, target);

    74     }

    75 

    76 //    MethodHandle make(MethodHandle filter1, MethodHandle filter2, MethodHandle target) {

    77 //        MethodHandle filter = make(filter1, filter2);

    78 //        return make(filter, target);

    79 //    }

    80 }