Initial annotation processor for NotNull and Nullable annotations

build.xml

@@ -246,6 +246,9 @@
 				<include name="**/*.st"/>
 				<include name="**/*.stg"/>
 			</fileset>
+			<fileset dir="${basedir}/runtime/JavaAnnotations/resources/">
+				<include name="**/*.Processor"/>
+			</fileset>
 			<fileset dir="${basedir}/runtime/JavaAnnotations/src/">
 				<include name="**/*.java"/>
 			</fileset>

runtime/JavaAnnotations/pom.xml

@@ -49,6 +49,18 @@
                 <directory>resources</directory>
             </resource>
         </resources>
+
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <compilerArgs>
+                        <compilerArg>-proc:none</compilerArg>
+                    </compilerArgs>
+                </configuration>
+            </plugin>
+        </plugins>
     </build>
 
 </project>

runtime/JavaAnnotations/resources/META-INF/services/javax.annotation.processing.Processor

@@ -0,0 +1 @@
+org.antlr.v4.runtime.misc.NullUsageProcessor

runtime/JavaAnnotations/src/org/antlr/v4/runtime/misc/NullUsageProcessor.java

@@ -0,0 +1,91 @@
+/*
+ * [The "BSD license"]
+ *  Copyright (c) 2013 Terence Parr
+ *  Copyright (c) 2013 Sam Harwell
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions
+ *  are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *  3. The name of the author may not be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.antlr.v4.runtime.misc;
+
+import javax.annotation.processing.AbstractProcessor;
+import javax.annotation.processing.RoundEnvironment;
+import javax.annotation.processing.SupportedAnnotationTypes;
+import javax.annotation.processing.SupportedSourceVersion;
+import javax.lang.model.SourceVersion;
+import javax.lang.model.element.TypeElement;
+import javax.tools.Diagnostic;
+
+import java.util.Set;
+
+/**
+ * A compile-time validator for correct usage of the {@link NotNull} and
+ * {@link Nullable} annotations.
+ *
+ * <p>The validation process checks the following items.</p>
+ *
+ * @author Sam Harwell
+ */
+@SupportedAnnotationTypes({NullUsageProcessor.NotNullClassName, NullUsageProcessor.NullableClassName})
+@SupportedSourceVersion(SourceVersion.RELEASE_6)
+public class NullUsageProcessor extends AbstractProcessor {
+	public static final String NotNullClassName = "org.antlr.v4.runtime.misc.NotNull";
+	public static final String NullableClassName = "org.antlr.v4.runtime.misc.Nullable";
+
+	public NullUsageProcessor() {
+	}
+
+	@Override
+	public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
+		if (!checkClassNameConstants()) {
+			return true;
+		}
+
+		return true;
+	}
+
+	private boolean checkClassNameConstants() {
+		boolean success = checkClassNameConstant(NotNullClassName, NotNull.class);
+		success &= checkClassNameConstant(NullableClassName, Nullable.class);
+		return success;
+	}
+
+	private boolean checkClassNameConstant(String className, Class<?> clazz) {
+		if (className == null) {
+			throw new NullPointerException("className");
+		}
+
+		if (clazz == null) {
+			throw new NullPointerException("clazz");
+		}
+
+		if (!className.equals(clazz.getCanonicalName())) {
+			processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, String.format("Unable to process null usage annotations due to class name mismatch: %s != %s", className, clazz.getCanonicalName()));
+			return false;
+		}
+
+		return true;
+	}
+}