/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.dyn;

import java.dyn.*;

import static sun.dyn.MemberName.uncaughtException;

/**

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

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

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

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

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

 * @author jrose

 */

public class FilterOneArgument extends BoundMethodHandle {

    protected final MethodHandle filter;  // Object -> Object

    protected final MethodHandle target;  // Object -> Object

    @Override

    public String toString() {

        return target.toString();

    }

    protected Object invoke(Object argument) throws Throwable {

        Object filteredArgument = filter.invokeExact(argument);

        return target.invokeExact(filteredArgument);

    }

    private static final MethodHandle INVOKE;

    static {

        try {

            INVOKE =

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

                                                         MethodType.genericMethodType(1));

        } catch (NoAccessException ex) {

            throw uncaughtException(ex);

        }

    }

    protected FilterOneArgument(MethodHandle filter, MethodHandle target) {

        super(Access.TOKEN, INVOKE);

        this.filter = filter;

        this.target = target;

    }

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

        if (filter == null)  return target;

        if (target == null)  return filter;

        return new FilterOneArgument(filter, target);

    }

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

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

//        return make(filter, target);

//    }

}