1 /*

     2  * Copyright (c) 2010, 2013, 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 /*

    27  * This file is available under and governed by the GNU General Public

    28  * License version 2 only, as published by the Free Software Foundation.

    29  * However, the following notice accompanied the original version of this

    30  * file, and Oracle licenses the original version of this file under the BSD

    31  * license:

    32  */

    33 /*

    34    Copyright 2009-2013 Attila Szegedi

    35 

    36    Licensed under both the Apache License, Version 2.0 (the "Apache License")

    37    and the BSD License (the "BSD License"), with licensee being free to

    38    choose either of the two at their discretion.

    39 

    40    You may not use this file except in compliance with either the Apache

    41    License or the BSD License.

    42 

    43    If you choose to use this file in compliance with the Apache License, the

    44    following notice applies to you:

    45 

    46        You may obtain a copy of the Apache License at

    47 

    48            http://www.apache.org/licenses/LICENSE-2.0

    49 

    50        Unless required by applicable law or agreed to in writing, software

    51        distributed under the License is distributed on an "AS IS" BASIS,

    52        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or

    53        implied. See the License for the specific language governing

    54        permissions and limitations under the License.

    55 

    56    If you choose to use this file in compliance with the BSD License, the

    57    following notice applies to you:

    58 

    59        Redistribution and use in source and binary forms, with or without

    60        modification, are permitted provided that the following conditions are

    61        met:

    62        * Redistributions of source code must retain the above copyright

    63          notice, this list of conditions and the following disclaimer.

    64        * Redistributions in binary form must reproduce the above copyright

    65          notice, this list of conditions and the following disclaimer in the

    66          documentation and/or other materials provided with the distribution.

    67        * Neither the name of the copyright holder nor the names of

    68          contributors may be used to endorse or promote products derived from

    69          this software without specific prior written permission.

    70 

    71        THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

    72        IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED

    73        TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

    74        PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER

    75        BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    76        CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    77        SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR

    78        BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

    79        WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

    80        OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

    81        ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    82 */

    83 

    84 package jdk.dynalink.beans;

    85 

    86 import java.lang.invoke.MethodHandle;

    87 import java.lang.invoke.MethodHandles;

    88 import java.lang.invoke.MethodType;

    89 import java.lang.reflect.Array;

    90 import java.util.StringTokenizer;

    91 import jdk.dynalink.CallSiteDescriptor;

    92 import jdk.dynalink.linker.LinkerServices;

    93 import jdk.dynalink.linker.support.Guards;

    94 import jdk.dynalink.linker.support.Lookup;

    95 

    96 /**

    97  * Base class for dynamic methods that dispatch to a single target Java method or constructor. Handles adaptation of the

    98  * target method to a call site type (including mapping variable arity methods to a call site signature with different

    99  * arity).

   100  */

   101 abstract class SingleDynamicMethod extends DynamicMethod {

   102     private static final MethodHandle CAN_CONVERT_TO = Lookup.findOwnStatic(MethodHandles.lookup(), "canConvertTo", boolean.class, LinkerServices.class, Class.class, Object.class);

   103 

   104     SingleDynamicMethod(final String name) {

   105         super(name);

   106     }

   107 

   108     /**

   109      * Returns true if this method is variable arity.

   110      * @return true if this method is variable arity.

   111      */

   112     abstract boolean isVarArgs();

   113 

   114     /**

   115      * Returns this method's native type.

   116      * @return this method's native type.

   117      */

   118     abstract MethodType getMethodType();

   119 

   120     /**

   121      * Given a specified call site descriptor, returns a method handle to this method's target. The target

   122      * should only depend on the descriptor's lookup, and it should only retrieve it (as a privileged

   123      * operation) when it is absolutely needed.

   124      * @param desc the call site descriptor to use.

   125      * @return the handle to this method's target method.

   126      */

   127     abstract MethodHandle getTarget(CallSiteDescriptor desc);

   128 

   129     @Override

   130     MethodHandle getInvocation(final CallSiteDescriptor callSiteDescriptor, final LinkerServices linkerServices) {

   131         return linkerServices.getWithLookup(()->getInvocation(getTarget(callSiteDescriptor),

   132                 callSiteDescriptor.getMethodType(), linkerServices), callSiteDescriptor);

   133     }

   134 

   135     @Override

   136     SingleDynamicMethod getMethodForExactParamTypes(final String paramTypes) {

   137         return typeMatchesDescription(paramTypes, getMethodType()) ? this : null;

   138     }

   139 

   140     @Override

   141     boolean contains(final SingleDynamicMethod method) {

   142         return getMethodType().parameterList().equals(method.getMethodType().parameterList());

   143     }

   144 

   145     static String getMethodNameWithSignature(final MethodType type, final String methodName, final boolean withReturnType) {

   146         final String typeStr = type.toString();

   147         final int retTypeIndex = typeStr.lastIndexOf(')') + 1;

   148         int secondParamIndex = typeStr.indexOf(',') + 1;

   149         if(secondParamIndex == 0) {

   150             secondParamIndex = retTypeIndex - 1;

   151         }

   152         final StringBuilder b = new StringBuilder();

   153         if (withReturnType) {

   154             b.append(typeStr, retTypeIndex, typeStr.length()).append(' ');

   155         }

   156         return b.append(methodName).append('(').append(typeStr, secondParamIndex, retTypeIndex).toString();

   157     }

   158 

   159     /**

   160      * Given a method handle and a call site type, adapts the method handle to the call site type. Performs type

   161      * conversions as needed using the specified linker services, and in case that the method handle is a vararg

   162      * collector, matches it to the arity of the call site. The type of the return value is only changed if it can be

   163      * converted using a conversion that loses neither precision nor magnitude, see

   164      * {@link LinkerServices#asTypeLosslessReturn(MethodHandle, MethodType)}.

   165      * @param target the method handle to adapt

   166      * @param callSiteType the type of the call site

   167      * @param linkerServices the linker services used for type conversions

   168      * @return the adapted method handle.

   169      */

   170     static MethodHandle getInvocation(final MethodHandle target, final MethodType callSiteType, final LinkerServices linkerServices) {

   171         final MethodHandle filteredTarget = linkerServices.filterInternalObjects(target);

   172         final MethodType methodType = filteredTarget.type();

   173         final int paramsLen = methodType.parameterCount();

   174         final boolean varArgs = target.isVarargsCollector();

   175         final MethodHandle fixTarget = varArgs ? filteredTarget.asFixedArity() : filteredTarget;

   176         final int fixParamsLen = varArgs ? paramsLen - 1 : paramsLen;

   177         final int argsLen = callSiteType.parameterCount();

   178         if(argsLen < fixParamsLen) {

   179             // Less actual arguments than number of fixed declared arguments; can't invoke.

   180             return null;

   181         }

   182         // Method handle has the same number of fixed arguments as the call site type

   183         if(argsLen == fixParamsLen) {

   184             // Method handle that matches the number of actual arguments as the number of fixed arguments

   185             final MethodHandle matchedMethod;

   186             if(varArgs) {

   187                 // If vararg, add a zero-length array of the expected type as the last argument to signify no variable

   188                 // arguments.

   189                 matchedMethod = MethodHandles.insertArguments(fixTarget, fixParamsLen, Array.newInstance(

   190                         methodType.parameterType(fixParamsLen).getComponentType(), 0));

   191             } else {

   192                 // Otherwise, just use the method

   193                 matchedMethod = fixTarget;

   194             }

   195             return createConvertingInvocation(matchedMethod, linkerServices, callSiteType);

   196         }

   197 

   198         // What's below only works for varargs

   199         if(!varArgs) {

   200             return null;

   201         }

   202 

   203         final Class<?> varArgType = methodType.parameterType(fixParamsLen);

   204         // Handle a somewhat sinister corner case: caller passes exactly one argument in the vararg position, and we

   205         // must handle both a prepacked vararg array as well as a genuine 1-long vararg sequence.

   206         if(argsLen == paramsLen) {

   207             final Class<?> callSiteLastArgType = callSiteType.parameterType(fixParamsLen);

   208             if(varArgType.isAssignableFrom(callSiteLastArgType)) {

   209                 // Call site signature guarantees we'll always be passed a single compatible array; just link directly

   210                 // to the method, introducing necessary conversions. Also, preserve it being a variable arity method.

   211                 return createConvertingInvocation(filteredTarget, linkerServices, callSiteType).asVarargsCollector(

   212                         callSiteLastArgType);

   213             }

   214 

   215             // This method handle takes the single argument and packs it into a newly allocated single-element array. It

   216             // will be used when the incoming argument can't be converted to the vararg array type (the "vararg packer"

   217             // method).

   218             final MethodHandle varArgCollectingInvocation = createConvertingInvocation(collectArguments(fixTarget,

   219                     argsLen), linkerServices, callSiteType);

   220 

   221             // Is call site type assignable from an array type (e.g. Object:int[], or Object[]:String[])

   222             final boolean isAssignableFromArray = callSiteLastArgType.isAssignableFrom(varArgType);

   223             // Do we have a custom conversion that can potentially convert the call site type to an array?

   224             final boolean isCustomConvertible = linkerServices.canConvert(callSiteLastArgType, varArgType);

   225             if(!isAssignableFromArray && !isCustomConvertible) {

   226                 // Call site signature guarantees the argument can definitely not be converted to an array (i.e. it is

   227                 // primitive), and no conversion can help with it either. Link immediately to a vararg-packing method

   228                 // handle.

   229                 return varArgCollectingInvocation;

   230             }

   231 

   232             // This method handle employs language-specific conversions to convert the last argument into an array of

   233             // vararg type.

   234             final MethodHandle arrayConvertingInvocation = createConvertingInvocation(MethodHandles.filterArguments(

   235                     fixTarget, fixParamsLen, linkerServices.getTypeConverter(callSiteLastArgType, varArgType)),

   236                     linkerServices, callSiteType);

   237 

   238             // This method handle determines whether the value can be converted to the array of vararg type using a

   239             // language-specific conversion.

   240             final MethodHandle canConvertArgToArray = MethodHandles.insertArguments(CAN_CONVERT_TO, 0, linkerServices,

   241                     varArgType);

   242 

   243             // This one adjusts the previous one for the location of the argument and the call site type.

   244             final MethodHandle canConvertLastArgToArray = MethodHandles.dropArguments(canConvertArgToArray, 0,

   245                     MethodType.genericMethodType(fixParamsLen).parameterList()).asType(callSiteType.changeReturnType(boolean.class));

   246 

   247             // This one takes the previous ones and combines them into a method handle that converts the argument into

   248             // a vararg array when it can, otherwise falls back to the vararg packer.

   249             final MethodHandle convertToArrayWhenPossible = MethodHandles.guardWithTest(canConvertLastArgToArray,

   250                     arrayConvertingInvocation, varArgCollectingInvocation);

   251 

   252             if(isAssignableFromArray) {

   253                 return MethodHandles.guardWithTest(

   254                         // Is incoming parameter already a compatible array?

   255                         Guards.isInstance(varArgType, fixParamsLen, callSiteType),

   256                         // Yes: just pass it to the method

   257                         createConvertingInvocation(fixTarget, linkerServices, callSiteType),

   258                         // No: either go through a custom conversion, or if it is not possible, go directly to the

   259                         // vararg packer.

   260                         isCustomConvertible ? convertToArrayWhenPossible : varArgCollectingInvocation);

   261             }

   262 

   263             // Just do the custom conversion with fallback to the vararg packer logic.

   264             assert isCustomConvertible;

   265             return convertToArrayWhenPossible;

   266         }

   267 

   268         // Remaining case: more than one vararg.

   269         return createConvertingInvocation(collectArguments(fixTarget, argsLen), linkerServices, callSiteType);

   270     }

   271 

   272     @SuppressWarnings("unused")

   273     private static boolean canConvertTo(final LinkerServices linkerServices, final Class<?> to, final Object obj) {

   274         return obj == null ? false : linkerServices.canConvert(obj.getClass(), to);

   275     }

   276 

   277     /**

   278      * Creates a method handle out of the original target that will collect the varargs for the exact component type of

   279      * the varArg array. Note that this will nicely trigger language-specific type converters for exactly those varargs

   280      * for which it is necessary when later passed to linkerServices.convertArguments().

   281      *

   282      * @param target the original method handle

   283      * @param parameterCount the total number of arguments in the new method handle

   284      * @return a collecting method handle

   285      */

   286     static MethodHandle collectArguments(final MethodHandle target, final int parameterCount) {

   287         final MethodType methodType = target.type();

   288         final int fixParamsLen = methodType.parameterCount() - 1;

   289         final Class<?> arrayType = methodType.parameterType(fixParamsLen);

   290         return target.asCollector(arrayType, parameterCount - fixParamsLen);

   291     }

   292 

   293     private static MethodHandle createConvertingInvocation(final MethodHandle sizedMethod,

   294             final LinkerServices linkerServices, final MethodType callSiteType) {

   295         return linkerServices.asTypeLosslessReturn(sizedMethod, callSiteType);

   296     }

   297 

   298     private static boolean typeMatchesDescription(final String paramTypes, final MethodType type) {

   299         final StringTokenizer tok = new StringTokenizer(paramTypes, ", ");

   300         for(int i = 1; i < type.parameterCount(); ++i) { // i = 1 as we ignore the receiver

   301             if(!(tok.hasMoreTokens() && typeNameMatches(tok.nextToken(), type.parameterType(i)))) {

   302                 return false;

   303             }

   304         }

   305         return !tok.hasMoreTokens();

   306     }

   307 

   308     private static boolean typeNameMatches(final String typeName, final Class<?> type) {

   309         return  typeName.equals(typeName.indexOf('.') == -1 ? type.getSimpleName() : type.getCanonicalName());

   310     }

   311 }