diff -r 000000000000 -r c880a8a8803b rt/emul/compact/src/main/java/java/lang/invoke/MethodHandleInfo.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/rt/emul/compact/src/main/java/java/lang/invoke/MethodHandleInfo.java Sat Aug 09 11:11:13 2014 +0200 @@ -0,0 +1,284 @@ +/* + * Copyright (c) 2012, 2013, 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.reflect.*; +import java.util.*; +import java.lang.invoke.MethodHandleNatives.Constants; +import java.lang.invoke.MethodHandles.Lookup; +import static java.lang.invoke.MethodHandleStatics.*; + +/** + * A symbolic reference obtained by cracking a direct method handle + * into its consitutent symbolic parts. + * To crack a direct method handle, call {@link Lookup#revealDirect Lookup.revealDirect}. + *

Direct Method Handles

+ * A direct method handle represents a method, constructor, or field without + * any intervening argument bindings or other transformations. + * The method, constructor, or field referred to by a direct method handle is called + * its underlying member. + * Direct method handles may be obtained in any of these ways: + * + * + *

Restrictions on Cracking

+ * Given a suitable {@code Lookup} object, it is possible to crack any direct method handle + * to recover a symbolic reference for the underlying method, constructor, or field. + * Cracking must be done via a {@code Lookup} object equivalent to that which created + * the target method handle, or which has enough access permissions to recreate + * an equivalent method handle. + *

+ * If the underlying method is caller sensitive, + * the direct method handle will have been "bound" to a particular caller class, the + * {@linkplain java.lang.invoke.MethodHandles.Lookup#lookupClass() lookup class} + * of the lookup object used to create it. + * Cracking this method handle with a different lookup class will fail + * even if the underlying method is public (like {@code Class.forName}). + *

+ * The requirement of lookup object matching provides a "fast fail" behavior + * for programs which may otherwise trust erroneous revelation of a method + * handle with symbolic information (or caller binding) from an unexpected scope. + * Use {@link java.lang.invoke.MethodHandles#reflectAs} to override this limitation. + * + *

Reference kinds

+ * The Lookup Factory Methods + * correspond to all major use cases for methods, constructors, and fields. + * These use cases may be distinguished using small integers as follows: + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + *
reference kinddescriptive namescopememberbehavior
{@code 1}{@code REF_getField}{@code class}{@code FT f;}{@code (T) this.f;}
{@code 2}{@code REF_getStatic}{@code class} or {@code interface}{@code static}
{@code FT f;}		{@code (T) C.f;}
{@code 3}{@code REF_putField}{@code class}{@code FT f;}{@code this.f = x;}
{@code 4}{@code REF_putStatic}{@code class}{@code static}
{@code FT f;}		{@code C.f = arg;}
{@code 5}{@code REF_invokeVirtual}{@code class}{@code T m(A*);}{@code (T) this.m(arg*);}
{@code 6}{@code REF_invokeStatic}{@code class} or {@code interface}{@code static}
{@code T m(A*);}		{@code (T) C.m(arg*);}
{@code 7}{@code REF_invokeSpecial}{@code class} or {@code interface}{@code T m(A*);}{@code (T) super.m(arg*);}
{@code 8}{@code REF_newInvokeSpecial}{@code class}{@code C(A*);}{@code new C(arg*);}
{@code 9}{@code REF_invokeInterface}{@code interface}{@code T m(A*);}{@code (T) this.m(arg*);}
+ * @since 1.8 + */ +public +interface MethodHandleInfo { + /** + * A direct method handle reference kind, + * as defined in the table above. + */ + public static final int + REF_getField = Constants.REF_getField, + REF_getStatic = Constants.REF_getStatic, + REF_putField = Constants.REF_putField, + REF_putStatic = Constants.REF_putStatic, + REF_invokeVirtual = Constants.REF_invokeVirtual, + REF_invokeStatic = Constants.REF_invokeStatic, + REF_invokeSpecial = Constants.REF_invokeSpecial, + REF_newInvokeSpecial = Constants.REF_newInvokeSpecial, + REF_invokeInterface = Constants.REF_invokeInterface; + + /** + * Returns the reference kind of the cracked method handle, which in turn + * determines whether the method handle's underlying member was a constructor, method, or field. + * See the table above for definitions. + * @return the integer code for the kind of reference used to access the underlying member + */ + public int getReferenceKind(); + + /** + * Returns the class in which the cracked method handle's underlying member was defined. + * @return the declaring class of the underlying member + */ + public Class getDeclaringClass(); + + /** + * Returns the name of the cracked method handle's underlying member. + * This is {@code "<init>"} if the underlying member was a constructor, + * else it is a simple method name or field name. + * @return the simple name of the underlying member + */ + public String getName(); + + /** + * Returns the nominal type of the cracked symbolic reference, expressed as a method type. + * If the reference is to a constructor, the return type will be {@code void}. + * If it is to a non-static method, the method type will not mention the {@code this} parameter. + * If it is to a field and the requested access is to read the field, + * the method type will have no parameters and return the field type. + * If it is to a field and the requested access is to write the field, + * the method type will have one parameter of the field type and return {@code void}. + *

+ * Note that original direct method handle may include a leading {@code this} parameter, + * or (in the case of a constructor) will replace the {@code void} return type + * with the constructed class. + * The nominal type does not include any {@code this} parameter, + * and (in the case of a constructor) will return {@code void}. + * @return the type of the underlying member, expressed as a method type + */ + public MethodType getMethodType(); + + // Utility methods. + // NOTE: class/name/type and reference kind constitute a symbolic reference + // member and modifiers are an add-on, derived from Core Reflection (or the equivalent) + + /** + * Reflects the underlying member as a method, constructor, or field object. + * If the underlying member is public, it is reflected as if by + * {@code getMethod}, {@code getConstructor}, or {@code getField}. + * Otherwise, it is reflected as if by + * {@code getDeclaredMethod}, {@code getDeclaredConstructor}, or {@code getDeclaredField}. + * The underlying member must be accessible to the given lookup object. + * @param the desired type of the result, either {@link Member} or a subtype + * @param expected a class object representing the desired result type {@code T} + * @param lookup the lookup object that created this MethodHandleInfo, or one with equivalent access privileges + * @return a reference to the method, constructor, or field object + * @exception ClassCastException if the member is not of the expected type + * @exception NullPointerException if either argument is {@code null} + * @exception IllegalArgumentException if the underlying member is not accessible to the given lookup object + */ + public T reflectAs(Class expected, Lookup lookup); + + /** + * Returns the access modifiers of the underlying member. + * @return the Java language modifiers for underlying member, + * or -1 if the member cannot be accessed + * @see Modifier + * @see #reflectAs + */ + public int getModifiers(); + + /** + * Determines if the underlying member was a variable arity method or constructor. + * Such members are represented by method handles that are varargs collectors. + * @implSpec + * This produces a result equivalent to: + * 

{@code
+     *     getReferenceKind() >= REF_invokeVirtual && Modifier.isTransient(getModifiers())
+     * }
+ * + * + * @return {@code true} if and only if the underlying member was declared with variable arity. + */ + // spelling derived from java.lang.reflect.Executable, not MethodHandle.isVarargsCollector + public default boolean isVarArgs() { + // fields are never varargs: + if (MethodHandleNatives.refKindIsField((byte) getReferenceKind())) + return false; + // not in the public API: Modifier.VARARGS + final int ACC_VARARGS = 0x00000080; // from JVMS 4.6 (Table 4.20) + assert(ACC_VARARGS == Modifier.TRANSIENT); + return Modifier.isTransient(getModifiers()); + } + + /** + * Returns the descriptive name of the given reference kind, + * as defined in the table above. + * The conventional prefix "REF_" is omitted. + * @param referenceKind an integer code for a kind of reference used to access a class member + * @return a mixed-case string such as {@code "getField"} + * @exception IllegalArgumentException if the argument is not a valid + * reference kind number + */ + public static String referenceKindToString(int referenceKind) { + if (!MethodHandleNatives.refKindIsValid(referenceKind)) + throw newIllegalArgumentException("invalid reference kind", referenceKind); + return MethodHandleNatives.refKindName((byte)referenceKind); + } + + /** + * Returns a string representation for a {@code MethodHandleInfo}, + * given the four parts of its symbolic reference. + * This is defined to be of the form {@code "RK C.N:MT"}, where {@code RK} is the + * {@linkplain #referenceKindToString reference kind string} for {@code kind}, + * {@code C} is the {@linkplain java.lang.Class#getName name} of {@code defc} + * {@code N} is the {@code name}, and + * {@code MT} is the {@code type}. + * These four values may be obtained from the + * {@linkplain #getReferenceKind reference kind}, + * {@linkplain #getDeclaringClass declaring class}, + * {@linkplain #getName member name}, + * and {@linkplain #getMethodType method type} + * of a {@code MethodHandleInfo} object. + * + * @implSpec + * This produces a result equivalent to: + * 
{@code
+     *     String.format("%s %s.%s:%s", referenceKindToString(kind), defc.getName(), name, type)
+     * }
+ * + * @param kind the {@linkplain #getReferenceKind reference kind} part of the symbolic reference + * @param defc the {@linkplain #getDeclaringClass declaring class} part of the symbolic reference + * @param name the {@linkplain #getName member name} part of the symbolic reference + * @param type the {@linkplain #getMethodType method type} part of the symbolic reference + * @return a string of the form {@code "RK C.N:MT"} + * @exception IllegalArgumentException if the first argument is not a valid + * reference kind number + * @exception NullPointerException if any reference argument is {@code null} + */ + public static String toString(int kind, Class defc, String name, MethodType type) { + Objects.requireNonNull(name); Objects.requireNonNull(type); + return String.format("%s %s.%s:%s", referenceKindToString(kind), defc.getName(), name, type); + } +}