Implemented annotation processor base class.

src/main/groovy/com/xinra/nucleus/apt/NucleusProcessor.java

@@ -0,0 +1,65 @@
+package com.xinra.nucleus.apt;
+
+import com.squareup.javapoet.AnnotationSpec;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+import javax.annotation.Generated;
+import javax.annotation.processing.AbstractProcessor;
+import javax.lang.model.SourceVersion;
+import javax.lang.model.element.Element;
+import javax.tools.Diagnostic;
+
+/**
+ * Base class for annotation Processors
+ * 
+ * @author Erik Hofer
+ */
+public abstract class NucleusProcessor extends AbstractProcessor {
+
+  /**
+   * Emits an error message (will be displayed in the IDE).
+   * 
+   * @param element the element to which the error belongs
+   * @param message the message (will be formatted with {@link String#format(String, Object...)})
+   * @param args arguments for the formatting
+   */
+  public void error(Element element, String message, Object... args) {
+    processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR,
+        String.format(message, args), element);
+  }
+
+  /**
+   * Returns {@link SourceVersion#latestSupported()}.
+   */
+  @Override
+  public SourceVersion getSupportedSourceVersion() {
+    return SourceVersion.latestSupported();
+  }
+
+  /**
+   * Returns a spec of @{@link Generated} with {@code value} set to the fully
+   * qualified name of the annotation processor and {@code date} set to the
+   * current date and time.
+   * 
+   * @param comments the value of {@link Generated#comments()} (omitted if {@code null})
+   */
+  public AnnotationSpec getGeneratedAnnotation(String comments) {
+    AnnotationSpec.Builder builder = AnnotationSpec.builder(Generated.class)
+        .addMember("value", "$S", this.getClass().getName())
+        .addMember("date", "$S", ZonedDateTime.now().format(DateTimeFormatter.ISO_INSTANT));
+    if(comments != null) {
+      builder.addMember("comments", "$S", comments);
+    }
+    return builder.build();
+  }
+
+  /**
+   * Returns a spec of @{@link Generated} with {@code value} set to the fully
+   * qualified name of the annotation processor, {@code date} set to the
+   * current date and time and without {@code comments}.
+   */
+  public AnnotationSpec getGeneratedAnnotation() {
+    return getGeneratedAnnotation(null);
+  }
+
+}