private void createInfrastructure() {
_classFab.addField("_next", _serviceInterface);
_classFab.addField("_filter", _filterInterface);
_classFab.addConstructor(
new Class[] {_serviceInterface, _filterInterface}, null, "{ _next = $1; _filter = $2; }");
_classFab.addInterface(_serviceInterface);
}
/**
* Finds a matching method in filterMethods for the given service method. A matching method has
* the same signature as the service interface method, but with an additional parameter matching
* the service interface itself.
*
* <p>The matching method signature from the list of filterMethods is removed and code generation
* strategies for making the two methods call each other are added.
*/
private void addBridgeMethod(MethodSignature ms, List filterMethods) {
Iterator i = filterMethods.iterator();
while (i.hasNext()) {
MethodSignature fms = (MethodSignature) i.next();
int position = _filterMethodAnalyzer.findServiceInterfacePosition(ms, fms);
if (position >= 0) {
addBridgeMethod(position, ms, fms);
i.remove();
return;
}
}
String message = PipelineMessages.unmatchedServiceMethod(ms, _filterInterface);
_errorLog.error(message, null, null);
BodyBuilder b = new BodyBuilder();
b.add("throw new org.ops4j.gaderian.ApplicationRuntimeException(");
b.addQuoted(message);
b.addln(");");
_classFab.addMethod(Modifier.PUBLIC, ms, b.toString());
}
/**
* Adds a method to the class which bridges from the service method to the corresponding method in
* the filter interface. The next service (either another Bridge, or the terminator at the end of
* the pipeline) is passed to the filter).
*/
private void addBridgeMethod(int position, MethodSignature ms, MethodSignature fms) {
StringBuffer buffer = new StringBuffer(100);
if (ms.getReturnType() != void.class) buffer.append("return ");
buffer.append("_filter.");
buffer.append(ms.getName());
buffer.append("(");
boolean comma = false;
int filterParameterCount = fms.getParameterTypes().length;
for (int i = 0; i < position; i++) {
if (comma) buffer.append(", ");
buffer.append("$");
// Add one to the index to get the parameter symbol ($0 is the implicit
// this parameter).
buffer.append(i + 1);
comma = true;
}
if (comma) buffer.append(", ");
// _next is the variable in -this- Bridge that points to the -next- Bridge
// or the terminator for the pipeline. The filter is expected to reinvoke the
// method on the _next that's passed to it.
buffer.append("_next");
for (int i = position + 1; i < filterParameterCount; i++) {
buffer.append(", $");
buffer.append(i);
}
buffer.append(");");
// This should work, unless the exception types turn out to not be compatble. We still
// don't do a check on that, and not sure that Javassist does either!
_classFab.addMethod(Modifier.PUBLIC, ms, buffer.toString());
}
private void createClass() {
List serviceMethods = new ArrayList();
List filterMethods = new ArrayList();
createInfrastructure();
MethodIterator mi = new MethodIterator(_serviceInterface);
while (mi.hasNext()) {
serviceMethods.add(mi.next());
}
boolean toStringMethodExists = mi.getToString();
mi = new MethodIterator(_filterInterface);
while (mi.hasNext()) {
filterMethods.add(mi.next());
}
while (!serviceMethods.isEmpty()) {
MethodSignature ms = (MethodSignature) serviceMethods.remove(0);
addBridgeMethod(ms, filterMethods);
}
reportExtraFilterMethods(filterMethods);
if (!toStringMethodExists)
ClassFabUtils.addToStringMethod(
_classFab, PipelineMessages.bridgeInstanceDescription(_serviceId, _serviceInterface));
Class bridgeClass = _classFab.createClass();
_constructor = bridgeClass.getConstructors()[0];
}