/*
Copyright 2009-2013 Attila Szegedi
Licensed under both the Apache License, Version 2.0 (the "Apache License")
and the BSD License (the "BSD License"), with licensee being free to
choose either of the two at their discretion.
You may not use this file except in compliance with either the Apache
License or the BSD License.
If you choose to use this file in compliance with the Apache License, the
following notice applies to you:
You may obtain a copy of the Apache License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied. See the License for the specific language governing
permissions and limitations under the License.
If you choose to use this file in compliance with the BSD License, the
following notice applies to you:
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the name of the copyright holder nor the names of
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this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER
BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.dynalang.dynalink.beans;
import java.lang.invoke.MethodHandles;
import java.util.Collection;
import java.util.Collections;
import org.dynalang.dynalink.CallSiteDescriptor;
import org.dynalang.dynalink.DynamicLinkerFactory;
import org.dynalang.dynalink.linker.GuardedInvocation;
import org.dynalang.dynalink.linker.GuardingDynamicLinker;
import org.dynalang.dynalink.linker.LinkRequest;
import org.dynalang.dynalink.linker.LinkerServices;
import org.dynalang.dynalink.linker.TypeBasedGuardingDynamicLinker;
/**
* A linker for POJOs. Normally used as the ultimate fallback linker by the {@link DynamicLinkerFactory} so it is given
* the chance to link calls to all objects that no other language runtime recognizes. Specifically, this linker will:
* <ul>
* <li>expose all public methods of form {@code setXxx()}, {@code getXxx()}, and {@code isXxx()} as property setters and
* getters for {@code dyn:setProp} and {@code dyn:getProp} operations;</li>
* <li>expose all public methods for invocation through {@code dyn:callMethod} operation;</li>
* <li>expose all public methods for retrieval for {@code dyn:getMethod} operation; the methods thus retrieved can then
* be invoked using {@code dyn:call};</li>
* <li>expose all public fields as properties, unless there are getters or setters for the properties of the same name;</li>
* <li>expose {@code dyn:getLength}, {@code dyn:getElem} and {@code dyn:setElem} on native Java arrays, as well as
* {@link java.util.List} and {@link java.util.Map} objects; ({@code dyn:getLength} works on any
* {@link java.util.Collection});</li>
* <li>expose a virtual property named {@code length} on Java arrays;</li>
* <li>expose {@code dyn:new} on instances of {@link StaticClass} as calls to constructors, including those static class
* objects that represent Java arrays (their constructors take a single {@code int} parameter representing the length of
* the array to create);</li>
* <li>expose static methods, fields, and properties of classes in a similar manner to how instance method, fields, and
* properties are exposed, on {@link StaticClass} objects.</li>
* <li>expose a virtual property named {@code static} on instances of {@link java.lang.Class} to access their
* {@link StaticClass}.</li>
* </ul>
* <p><strong>Overloaded method resolution</strong> is performed automatically for property setters, methods, and
* constructors. Additionally, manual overloaded method selection is supported by having a call site specify a name for
* a method that contains an explicit signature, i.e. {@code dyn:getMethod:parseInt(String,int)}. You can use
* non-qualified class names in such signatures regardless of those classes' packages, they will match any class with
* the same non-qualified name. You only have to use a fully qualified class name in case non-qualified class names
* would cause selection ambiguity (that is extremely rare).</p>
* <p><strong>Variable argument invocation</strong> is handled for both methods and constructors.</p>
* <p>Currently, only public fields and methods are supported. Any Lookup objects passed in the
* {@link LinkRequest}s are ignored and {@link MethodHandles#publicLookup()} is used instead.</p>
*
* @author Attila Szegedi
*/
public class BeansLinker implements GuardingDynamicLinker {
private static final ClassValue<TypeBasedGuardingDynamicLinker> linkers = new ClassValue<TypeBasedGuardingDynamicLinker>() {
@Override
protected TypeBasedGuardingDynamicLinker computeValue(Class<?> clazz) {
// If ClassValue.put() were public, we could just pre-populate with these known mappings...
return
clazz == Class.class ? new ClassLinker() :
clazz == StaticClass.class ? new StaticClassLinker() :
DynamicMethod.class.isAssignableFrom(clazz) ? new DynamicMethodLinker() :
new BeanLinker(clazz);
}
};
/**
* Creates a new POJO linker.
*/
public BeansLinker() {
}
/**
* Returns a bean linker for a particular single class. Useful when you need to override or extend the behavior of
* linking for some classes in your language runtime's linker, but still want to delegate to the default behavior in
* some cases.
* @param clazz the class
* @return a bean linker for that class
*/
public static TypeBasedGuardingDynamicLinker getLinkerForClass(Class<?> clazz) {
return linkers.get(clazz);
}
/**
* Returns a collection of names of all readable instance properties of a class.
* @param clazz the class
* @return a collection of names of all readable instance properties of a class.
*/
public static Collection<String> getReadableInstancePropertyNames(Class<?> clazz) {
TypeBasedGuardingDynamicLinker linker = getLinkerForClass(clazz);
if(linker instanceof BeanLinker) {
return ((BeanLinker)linker).getReadablePropertyNames();
}
return Collections.emptySet();
}
/**
* Returns a collection of names of all writable instance properties of a class.
* @param clazz the class
* @return a collection of names of all writable instance properties of a class.
*/
public static Collection<String> getWritableInstancePropertyNames(Class<?> clazz) {
TypeBasedGuardingDynamicLinker linker = getLinkerForClass(clazz);
if(linker instanceof BeanLinker) {
return ((BeanLinker)linker).getWritablePropertyNames();
}
return Collections.emptySet();
}
/**
* Returns a collection of names of all instance methods of a class.
* @param clazz the class
* @return a collection of names of all instance methods of a class.
*/
public static Collection<String> getInstanceMethodNames(Class<?> clazz) {
TypeBasedGuardingDynamicLinker linker = getLinkerForClass(clazz);
if(linker instanceof BeanLinker) {
return ((BeanLinker)linker).getMethodNames();
}
return Collections.emptySet();
}
/**
* Returns a collection of names of all readable static properties of a class.
* @param clazz the class
* @return a collection of names of all readable static properties of a class.
*/
public static Collection<String> getReadableStaticPropertyNames(Class<?> clazz) {
return StaticClassLinker.getReadableStaticPropertyNames(clazz);
}
/**
* Returns a collection of names of all writable static properties of a class.
* @param clazz the class
* @return a collection of names of all writable static properties of a class.
*/
public static Collection<String> getWritableStaticPropertyNames(Class<?> clazz) {
return StaticClassLinker.getWritableStaticPropertyNames(clazz);
}
/**
* Returns a collection of names of all static methods of a class.
* @param clazz the class
* @return a collection of names of all static methods of a class.
*/
public static Collection<String> getStaticMethodNames(Class<?> clazz) {
return StaticClassLinker.getStaticMethodNames(clazz);
}
@Override
public GuardedInvocation getGuardedInvocation(LinkRequest request, final LinkerServices linkerServices)
throws Exception {
final CallSiteDescriptor callSiteDescriptor = request.getCallSiteDescriptor();
final int l = callSiteDescriptor.getNameTokenCount();
// All names conforming to the dynalang MOP should have at least two tokens, the first one being "dyn"
if(l < 2 || "dyn" != callSiteDescriptor.getNameToken(CallSiteDescriptor.SCHEME)) {
return null;
}
final Object receiver = request.getReceiver();
if(receiver == null) {
// Can't operate on null
return null;
}
return getLinkerForClass(receiver.getClass()).getGuardedInvocation(request, linkerServices);
}
}