/* * Copyright 2008-2009 Sun Microsystems, Inc. All Rights Reserved. * 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. Sun designates this * particular file as subject to the "Classpath" exception as provided * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. */ package java.dyn; /** * Syntactic marker to request javac to emit an {@code invokedynamic} instruction. * An {@code invokedynamic} instruction is a 5-byte bytecoded instruction * which begins with an opcode byte of value 186 ({@code 0xBA}), * and is followed by a two-byte index of a {@code NameAndType} constant * pool entry, then by two zero bytes. The constant pool reference gives * the method name and argument and return types of the call site; there * is no other information provided at the call site. *

* The {@code invokedynamic} instruction is incomplete without a target method. * The target method is a property of the reified call site object * (of type {@link CallSite}) which is in a one-to-one association with each * corresponding {@code invokedynamic} instruction. The call site object * is initially produced by a bootstrap method associated with * the call site, via the various overloadings of {@link Linkage#registerBootstrapMethod}. *

* The type {@code InvokeDynamic} has no particular meaning as a * class or interface supertype, or an object type; it can never be instantiated. * Logically, it denotes a source of all dynamically typed methods. * It may be viewed as a pure syntactic marker (an importable one) of static calls. *

* Here are some examples of usage: *

 * Object x; String s; int i;
 * x = InvokeDynamic.greet("world"); // greet(Ljava/lang/String;)Ljava/lang/Object;
 * s = InvokeDynamic.<String>hail(x); // hail(Ljava/lang/Object;)Ljava/lang/String;
 * InvokeDynamic.<void>cogito(); // cogito()V
 * i = InvokeDynamic.<int>#"op:+"(2, 3); // "op:+"(II)I
 * 
* Each of the above calls generates a single invokedynamic instruction * with the name-and-type descriptors indicated in the comments. * The argument types are taken directly from the actual arguments, * while the return type is taken from the type parameter. * (This type parameter may be a primtive, and it defaults to {@code Object}.) * The final example uses a special syntax for uttering non-Java names. * Any name legal to the JVM may be given between the double quotes. * None of these calls is complete without a bootstrap method, * which must be registered by the static initializer of the enclosing class. * @author John Rose, JSR 292 EG */ public final class InvokeDynamic { private InvokeDynamic() { throw new InternalError(); } // do not instantiate // no statically defined static methods }