// Copyright 2006 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the 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.
package org.apache.tapestry.internal.services;
import java.lang.annotation.Annotation;
import java.util.Iterator;
import java.util.List;
import org.apache.tapestry.MarkupWriter;
import org.apache.tapestry.internal.util.MethodInvocationBuilder;
import org.apache.tapestry.ioc.internal.util.InternalUtils;
import org.apache.tapestry.ioc.util.BodyBuilder;
import org.apache.tapestry.model.MutableComponentModel;
import org.apache.tapestry.services.ClassTransformation;
import org.apache.tapestry.services.ComponentClassTransformWorker;
import org.apache.tapestry.services.MethodFilter;
import org.apache.tapestry.services.MethodSignature;
/**
* Converts one of the methods of {@link org.apache.tapestry.runtime.Component} into a chain of
* command that, itself, invokes certain methods (render phase methods) marked with an annotation,
* or named in a specific way.
*/
public class ComponentLifecycleMethodWorker implements ComponentClassTransformWorker
{
private static final String CHECK_ABORT_FLAG = "if ($2.isAborted()) return;";
private final Class<? extends Annotation> _methodAnnotation;
private final MethodSignature _lifecycleMethodSignature;
private final String _lifecycleMethodName;
private final boolean _reverse;
private final MethodInvocationBuilder _invocationBuilder = new MethodInvocationBuilder();
/**
* Normal method invocation: parent class, then methods in ascending alphabetical order. Reverse
* order: method in descending alphabetical order, then parent class.
*
* @param lifecycleMethodSignature
* the signature of the method to be implemented in the component class
* @param methodAnnotation
* the class of the corresponding annotation
* @param reverse
* if true, the normal method invocation order is reversed
*/
public ComponentLifecycleMethodWorker(MethodSignature lifecycleMethodSignature,
Class<? extends Annotation> methodAnnotation, boolean reverse)
{
_lifecycleMethodSignature = lifecycleMethodSignature;
_methodAnnotation = methodAnnotation;
_reverse = reverse;
_lifecycleMethodName = lifecycleMethodSignature.getMethodName();
// If we ever add more parameters to the methods, then we can add more to the invocation builder.
// *Never* expose the Event parameter ($2), it is for internal use only.
_invocationBuilder.addParameter(MarkupWriter.class.getName(), "$1");
}
@Override
public String toString()
{
return String.format("ComponentLifecycleMethodWorker[%s]", _methodAnnotation.getName());
}
public void transform(final ClassTransformation transformation, MutableComponentModel model)
{
MethodFilter filter = new MethodFilter()
{
public boolean accept(MethodSignature signature)
{
// These methods get added to base classes and otherwise fall into this filter. If
// we don't
// include this filter, then we get endless loops.
if (signature.equals(_lifecycleMethodSignature))
return false;
// A degenerate case would be a method, say beginRender(), with an conflicting
// annotation, say @AfterRender. In that case, this code is broken, as the method
// will be invoked for both phases!
return signature.getMethodName().equals(_lifecycleMethodName)
|| transformation.getMethodAnnotation(signature, _methodAnnotation) != null;
}
};
List<MethodSignature> methods = transformation.findMethods(filter);
// Except in the root class, don't bother to add a new method unless there's something to
// call (beside super).
if (methods.isEmpty())
return;
BodyBuilder builder = new BodyBuilder();
builder.begin();
// If in a subclass, and in normal order mode, invoke the super class version first.
if (!(_reverse || model.isRootClass()))
{
builder.addln("super.%s($$);", _lifecycleMethodName);
builder.addln(CHECK_ABORT_FLAG);
}
Iterator<MethodSignature> i = _reverse ? InternalUtils.reverseIterator(methods) : methods
.iterator();
while (i.hasNext())
addMethodCallToBody(builder, i.next(), transformation);
// In reverse order in a a subclass, invoke the super method last.
if (_reverse && !model.isRootClass())
builder.addln("super.%s($$);", _lifecycleMethodName);
builder.end();
// Let's see if this works; for base classes, we are adding an empty method the adding a
// non-empty
// method "on top of it".
transformation.addMethod(_lifecycleMethodSignature, builder.toString());
}
private void addMethodCallToBody(BodyBuilder builder, MethodSignature sig,
ClassTransformation transformation)
{
boolean isVoid = sig.getReturnType().equals("void");
if (!isVoid)
{
// If we're not going to invoke storeResult(), then there's no reason to invoke
// setSource().
builder.addln("$2.setSource(this, \"%s.%s\");", transformation.getClassName(), sig
.getMediumDescription());
builder.add("if ($2.storeResult(($w) ");
}
// This is the best part; the method can even be private and this still works. It's a lot
// like how javac enables access to private members for inner classes (by introducing
// synthetic, static methods).
builder.add(_invocationBuilder.buildMethodInvocation(sig, transformation));
// Now, if non void ...
if (!isVoid)
{
// Complete the call to storeResult(). If storeResult() returns true, then
// the event is aborted and no further processing is required.
builder.addln(")) return;");
}
else
builder.addln(";");
}
}