--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/lang/invoke/BootstrapCallInfo.java Fri Sep 08 10:46:46 2017 -0700
@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2017, Oracle and/or its affiliates. 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. 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 java.lang.invoke;
+
+import java.lang.invoke.MethodHandles.Lookup;
+
+/**
+ * An interface providing full static information about a particular
+ * call to a
+ * <a href="package-summary.html#bsm">bootstrap method</a> of an
+ * dynamic call site or dynamic constant.
+ * This information includes the method itself, the associated
+ * name and type, and any associated static arguments.
+ * <p>
+ * If a bootstrap method declares exactly two arguments, and is
+ * not of variable arity, then it is fed only two arguments by
+ * the JVM, the {@linkplain Lookup lookup object} and an instance
+ * of {@code BootstrapCallInfo} which supplies the rest of the
+ * information about the call.
+ * <p>
+ * The API for accessing the static arguments allows the bootstrap
+ * method to reorder the resolution (in the constant pool) of the
+ * static arguments, and to catch errors resulting from the resolution.
+ * This mode of evaluation <em>pulls</em> bootstrap parameters from
+ * the JVM under control of the bootstrap method, as opposed to
+ * the JVM <em>pushing</em> parameters to a bootstrap method
+ * by resolving them all before the bootstrap method is called.
+ * @apiNote
+ * <p>
+ * The {@linkplain Lookup lookup object} is <em>not</em> included in this
+ * bundle of information, so as not to obscure the access control
+ * logic of the program.
+ * In cases where there are many thousands of parameters, it may
+ * be preferable to pull their resolved values, either singly or in
+ * batches, rather than wait until all of them have been resolved
+ * before a constant or call site can be used.
+ * <p>
+ * A push mode bootstrap method can be adapted to a pull mode
+ * bootstrap method, and vice versa. For example, this generic
+ * adapter pops a push-mode bootstrap method from the beginning
+ * of the static argument list, eagerly resolves all the remaining
+ * static arguments, and invokes the popped method in push mode.
+ * The callee has no way of telling that it was not called directly
+ * from the JVM.
+ * <blockquote><pre>{@code
+static Object genericBSM(Lookup lookup, BootstrapCallInfo<Object> bsci)
+ throws Throwable {
+ ArrayList<Object> args = new ArrayList<>();
+ args.add(lookup);
+ args.add(bsci.invocationName());
+ args.add(bsci.invocationType());
+ MethodHandle bsm = (MethodHandle) bsci.get(0);
+ List<Object> restOfArgs = bsci.asList().subList(1, bsci.size();
+ // the next line eagerly resolves all remaining static arguments:
+ args.addAll(restOfArgs);
+ return bsm.invokeWithArguments(args);
+}
+ * }</pre></blockquote>
+ *
+ * <p>
+ * In the other direction, here is a combinator which pops
+ * a pull-mode bootstrap method from the beginning of a list of
+ * static argument values (already resolved), reformats all of
+ * the arguments into a pair of a lookup and a {@code BootstrapCallInfo},
+ * and invokes the popped method. Again the callee has no way of
+ * telling it was not called directly by the JVM, except that
+ * all of the constant values will appear as resolved.
+ * Put another way, if any constant fails to resolve, the
+ * callee will not be able to catch the resulting error,
+ * since the error will be thrown by the JVM before the
+ * bootstrap method is entered.
+ * <blockquote><pre>{@code
+static Object genericBSM(Lookup lookup, String name, Object type,
+ MethodHandle bsm, Object... args)
+ throws Throwable {
+ ConstantGroup cons = ConstantGroup.makeConstantGroup(Arrays.asList(args));
+ BootstrapCallInfo<Object> bsci = makeBootstrapCallInfo(bsm, name, type, cons);
+ return bsm.invoke(lookup, bsci);
+}
+ * }</pre></blockquote>
+ *
+ * @since 1.10
+ */
+// public
+interface BootstrapCallInfo<T> extends ConstantGroup {
+ /** Returns the bootstrap method for this call.
+ * @return the bootstrap method
+ */
+ MethodHandle bootstrapMethod();
+
+ /** Returns the method name or constant name for this call.
+ * @return the method name or constant name
+ */
+ String invocationName();
+
+ /** Returns the method type or constant type for this call.
+ * @return the method type or constant type
+ */
+ T invocationType();
+
+ /**
+ * Make a new bootstrap call descriptor with the given components.
+ * @param bsm bootstrap method
+ * @param name invocation name
+ * @param type invocation type
+ * @param constants the additional static arguments for the bootstrap method
+ * @param <T> the type of the invocation type, either {@link MethodHandle} or {@link Class}
+ * @return a new bootstrap call descriptor with the given components
+ */
+ static <T> BootstrapCallInfo<T> makeBootstrapCallInfo(MethodHandle bsm,
+ String name,
+ T type,
+ ConstantGroup constants) {
+ AbstractConstantGroup.BSCIWithCache<T> bsci = new AbstractConstantGroup.BSCIWithCache<>(bsm, name, type, constants.size());
+ final Object NP = AbstractConstantGroup.BSCIWithCache.NOT_PRESENT;
+ bsci.initializeCache(constants.asList(NP), NP);
+ return bsci;
+ }
+}