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30 day Evaluation Version distributed via the Maven Jar Repository. Clover is not free. You have 30 days to evaluate it. Please visit http://www.thecortex.net/clover to obtain a licensed version of Clover | |||||||||||||||||||
Source file | Conditionals | Statements | Methods | TOTAL | |||||||||||||||
BridgeBuilder.java | 96.2% | 98.7% | 100% | 98.1% |
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// Copyright 2004, 2005 The Apache Software Foundation
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package org.apache.hivemind.lib.pipeline;
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import java.lang.reflect.Constructor;
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import java.lang.reflect.Modifier;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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import org.apache.hivemind.ApplicationRuntimeException;
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import org.apache.hivemind.ErrorLog;
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import org.apache.hivemind.service.BodyBuilder;
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import org.apache.hivemind.service.ClassFab;
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import org.apache.hivemind.service.ClassFabUtils;
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import org.apache.hivemind.service.ClassFactory;
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import org.apache.hivemind.service.MethodIterator;
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import org.apache.hivemind.service.MethodSignature;
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/**
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* Used by the {@link org.apache.hivemind.lib.pipeline.PipelineAssembler}class to create bridge
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* classes and to create instances of briddge classes.
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*
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* @author Howard Lewis Ship
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*/
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class BridgeBuilder
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{ |
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private ErrorLog _errorLog;
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private String _serviceId;
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private Class _serviceInterface;
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private Class _filterInterface;
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private ClassFab _classFab;
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private FilterMethodAnalyzer _filterMethodAnalyzer;
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private Constructor _constructor;
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BridgeBuilder(ErrorLog errorLog, String serviceId, Class serviceInterface, |
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Class filterInterface, ClassFactory classFactory) |
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{ |
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_errorLog = errorLog; |
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_serviceId = serviceId; |
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_serviceInterface = serviceInterface; |
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_filterInterface = filterInterface; |
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String name = ClassFabUtils.generateClassName(_serviceInterface); |
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_classFab = classFactory.newClass(name, Object.class);
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_filterMethodAnalyzer = new FilterMethodAnalyzer(serviceInterface);
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} |
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private void createClass() |
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{ |
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List serviceMethods = new ArrayList();
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List filterMethods = new ArrayList();
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createInfrastructure(); |
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MethodIterator mi = new MethodIterator(_serviceInterface);
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while (mi.hasNext())
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{ |
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serviceMethods.add(mi.next()); |
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} |
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boolean toStringMethodExists = mi.getToString();
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mi = new MethodIterator(_filterInterface);
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while (mi.hasNext())
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{ |
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filterMethods.add(mi.next()); |
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} |
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while (!serviceMethods.isEmpty())
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{ |
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MethodSignature ms = (MethodSignature) serviceMethods.remove(0); |
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addBridgeMethod(ms, filterMethods); |
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} |
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reportExtraFilterMethods(filterMethods); |
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if (!toStringMethodExists)
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ClassFabUtils.addToStringMethod(_classFab, PipelineMessages.bridgeInstanceDescription( |
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_serviceId, |
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_serviceInterface)); |
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Class bridgeClass = _classFab.createClass(); |
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_constructor = bridgeClass.getConstructors()[0]; |
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} |
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private void createInfrastructure() |
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{ |
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_classFab.addField("_next", _serviceInterface);
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_classFab.addField("_filter", _filterInterface);
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_classFab.addConstructor(new Class[]
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{ _serviceInterface, _filterInterface }, null, "{ _next = $1; _filter = $2; }"); |
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_classFab.addInterface(_serviceInterface); |
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} |
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/**
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* Instantiates a bridge object.
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*
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* @param nextBridge
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* the next Bridge object in the pipeline, or the terminator service
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* @param filter
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* the filter object for this step of the pipeline
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*/
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public Object instantiateBridge(Object nextBridge, Object filter)
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{ |
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if (_constructor == null) |
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createClass(); |
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try
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{ |
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return _constructor.newInstance(new Object[] |
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{ nextBridge, filter }); |
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} |
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catch (Exception ex)
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{ |
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throw new ApplicationRuntimeException(ex); |
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} |
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} |
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private void reportExtraFilterMethods(List filterMethods) |
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{ |
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Iterator i = filterMethods.iterator(); |
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while (i.hasNext())
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{ |
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MethodSignature ms = (MethodSignature) i.next(); |
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_errorLog.error(PipelineMessages.extraFilterMethod( |
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ms, |
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_filterInterface, |
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_serviceInterface, |
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_serviceId), null, null); |
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} |
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} |
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/**
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* Finds a matching method in filterMethods for the given service method. A matching method has
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* the same signature as the service interface method, but with an additional parameter matching
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* the service interface itself.
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* <p>
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* The matching method signature from the list of filterMethods is removed and code generation
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* strategies for making the two methods call each other are added.
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*/
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private void addBridgeMethod(MethodSignature ms, List filterMethods) |
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{ |
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Iterator i = filterMethods.iterator(); |
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while (i.hasNext())
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{ |
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MethodSignature fms = (MethodSignature) i.next(); |
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int position = _filterMethodAnalyzer.findServiceInterfacePosition(ms, fms);
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if (position >= 0)
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{ |
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addBridgeMethod(position, ms, fms); |
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i.remove(); |
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return;
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} |
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} |
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String message = PipelineMessages.unmatchedServiceMethod(ms, _filterInterface); |
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_errorLog.error(message, null, null); |
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BodyBuilder b = new BodyBuilder();
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b.add("throw new org.apache.hivemind.ApplicationRuntimeException(");
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b.addQuoted(message); |
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b.addln(");");
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_classFab.addMethod(Modifier.PUBLIC, ms, b.toString()); |
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} |
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/**
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* Adds a method to the class which bridges from the service method to the corresponding method
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* in the filter interface. The next service (either another Bridge, or the terminator at the
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* end of the pipeline) is passed to the filter).
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*/
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private void addBridgeMethod(int position, MethodSignature ms, MethodSignature fms) |
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{ |
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StringBuffer buffer = new StringBuffer(100);
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if (ms.getReturnType() != void.class) |
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buffer.append("return ");
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buffer.append("_filter.");
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buffer.append(ms.getName()); |
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buffer.append("(");
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boolean comma = false; |
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int filterParameterCount = fms.getParameterTypes().length;
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for (int i = 0; i < position; i++) |
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{ |
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if (comma)
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buffer.append(", ");
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buffer.append("$");
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// Add one to the index to get the parameter symbol ($0 is the implicit
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// this parameter).
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buffer.append(i + 1); |
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comma = true;
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} |
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if (comma)
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buffer.append(", ");
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// _next is the variable in -this- Bridge that points to the -next- Bridge
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// or the terminator for the pipeline. The filter is expected to reinvoke the
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// method on the _next that's passed to it.
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buffer.append("_next");
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for (int i = position + 1; i < filterParameterCount; i++) |
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{ |
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buffer.append(", $");
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buffer.append(i); |
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} |
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buffer.append(");");
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// This should work, unless the exception types turn out to not be compatble. We still
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// don't do a check on that, and not sure that Javassist does either!
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_classFab.addMethod(Modifier.PUBLIC, ms, buffer.toString()); |
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} |
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} |
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