79 lines
2.9 KiB
Java
79 lines
2.9 KiB
Java
package dev.kske.eventbus.ap;
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import java.util.Set;
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import javax.annotation.processing.*;
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import javax.lang.model.SourceVersion;
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import javax.lang.model.element.*;
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import javax.lang.model.type.*;
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import javax.tools.Diagnostic.Kind;
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import dev.kske.eventbus.core.*;
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/**
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* This annotation processor checks event handlers for common mistakes which can only be detected
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* during runtime otherwise.
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*
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* @author Kai S. K. Engelbart
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* @since 1.0.0
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*/
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@SupportedAnnotationTypes("dev.kske.eventbus.core.Event")
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@SupportedSourceVersion(SourceVersion.RELEASE_11)
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public class EventProcessor extends AbstractProcessor {
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@Override
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public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
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for (Element annotatedElement : roundEnv.getElementsAnnotatedWith(Event.class)) {
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ExecutableElement method = (ExecutableElement) annotatedElement;
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Event eventAnnotation = method.getAnnotation(Event.class);
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boolean useParameter = false;
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// Determine how the event type is defined
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try {
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eventAnnotation.eventType();
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} catch (MirroredTypeException e) {
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// Task failed successfully
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useParameter = processingEnv.getTypeUtils().isSameType(e.getTypeMirror(),
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processingEnv.getElementUtils()
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.getTypeElement(Event.USE_PARAMETER.class.getCanonicalName()).asType());
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}
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// Check for correct method signature and return type
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if (method.getParameters().size() == 0 && useParameter)
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error(method, "The method or the annotation should define the event type");
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if (method.getParameters().size() == 1 && !useParameter)
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error(method, "Either the method or the annotation should define the event type");
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if (method.getParameters().size() > 1)
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error(method, "Method should not have more than one parameter");
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if (!method.getReturnType().getKind().equals(TypeKind.VOID))
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error(method, "Method needs a return type of void");
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// Check event type
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var paramType = ((ExecutableType) method.asType()).getParameterTypes().get(0);
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if (useParameter && !processingEnv.getTypeUtils().isAssignable(paramType,
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processingEnv.getElementUtils()
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.getTypeElement(IEvent.class.getCanonicalName()).asType()))
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error(method.getParameters().get(0), "Parameter should implement IEvent");
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// Check listener for interface implementation
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if (!((TypeElement) method.getEnclosingElement()).getInterfaces().contains(processingEnv
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.getElementUtils().getTypeElement(EventListener.class.getCanonicalName()).asType()))
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warning(method.getEnclosingElement(),
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"Class should implement EventListener interface");
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}
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return true;
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}
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private void warning(Element e, String msg, Object... args) {
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processingEnv.getMessager().printMessage(Kind.WARNING, String.format(msg, args), e);
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}
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private void error(Element e, String msg, Object... args) {
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processingEnv.getMessager().printMessage(Kind.ERROR, String.format(msg, args), e);
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}
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}
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