/*

 * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package javax.annotation.processing;

import java.util.Set;

import java.util.HashSet;

import java.util.Collections;

import javax.lang.model.element.*;

import javax.lang.model.SourceVersion;

import javax.tools.Diagnostic;

/**

 * An abstract annotation processor designed to be a convenient

 * superclass for most concrete annotation processors.  This class

 * examines annotation values to compute the {@linkplain

 * #getSupportedOptions options}, {@linkplain

 * #getSupportedAnnotationTypes annotations}, and {@linkplain

 * #getSupportedSourceVersion source version} supported by its

 * subtypes.

 *

 * <p>The getter methods may {@linkplain Messager#printMessage issue

 * warnings} about noteworthy conditions using the facilities available

 * after the processor has been {@linkplain #isInitialized

 * initialized}.

 *

 * <p>Subclasses are free to override the implementation and

 * specification of any of the methods in this class as long as the

 * general {@link javax.annotation.processing.Processor Processor}

 * contract for that method is obeyed.

 *

 * @author Joseph D. Darcy

 * @author Scott Seligman

 * @author Peter von der Ahé

 * @since 1.6

 */

public abstract class AbstractProcessor implements Processor {

    /**

     * Processing environment providing by the tool framework.

     */

    protected ProcessingEnvironment processingEnv;

    private boolean initialized = false;

    /**

     * Constructor for subclasses to call.

     */

    protected AbstractProcessor() {}

    /**

     * If the processor class is annotated with {@link

     * SupportedOptions}, return an unmodifiable set with the same set

     * of strings as the annotation.  If the class is not so

     * annotated, an empty set is returned.

     *

     * @return the options recognized by this processor, or an empty

     * set if none

     */

    public Set<String> getSupportedOptions() {

        SupportedOptions so = this.getClass().getAnnotation(SupportedOptions.class);

        if  (so == null)

            return Collections.emptySet();

        else

            return arrayToSet(so.value());

    }

    /**

     * If the processor class is annotated with {@link

     * SupportedAnnotationTypes}, return an unmodifiable set with the

     * same set of strings as the annotation.  If the class is not so

     * annotated, an empty set is returned.

     *

     * @return the names of the annotation types supported by this

     * processor, or an empty set if none

     */

    public Set<String> getSupportedAnnotationTypes() {

            SupportedAnnotationTypes sat = this.getClass().getAnnotation(SupportedAnnotationTypes.class);

            if  (sat == null) {

                if (isInitialized())

                    processingEnv.getMessager().printMessage(Diagnostic.Kind.WARNING,

                                                             "No SupportedAnnotationTypes annotation " +

                                                             "found on " + this.getClass().getName() +

                                                             ", returning an empty set.");

                return Collections.emptySet();

            }

            else

                return arrayToSet(sat.value());

        }

    /**

     * If the processor class is annotated with {@link

     * SupportedSourceVersion}, return the source version in the

     * annotation.  If the class is not so annotated, {@link

     * SourceVersion#RELEASE_6} is returned.

     *

     * @return the latest source version supported by this processor

     */

    public SourceVersion getSupportedSourceVersion() {

        SupportedSourceVersion ssv = this.getClass().getAnnotation(SupportedSourceVersion.class);

        SourceVersion sv = null;

        if (ssv == null) {

            sv = SourceVersion.RELEASE_6;

            if (isInitialized())

                processingEnv.getMessager().printMessage(Diagnostic.Kind.WARNING,

                                                         "No SupportedSourceVersion annotation " +

                                                         "found on " + this.getClass().getName() +

                                                         ", returning " + sv + ".");

        } else

            sv = ssv.value();

        return sv;

    }

    /**

     * Initializes the processor with the processing environment by

     * setting the {@code processingEnv} field to the value of the

     * {@code processingEnv} argument.  An {@code

     * IllegalStateException} will be thrown if this method is called

     * more than once on the same object.

     *

     * @param processingEnv environment to access facilities the tool framework

     * provides to the processor

     * @throws IllegalStateException if this method is called more than once.

     */

    public synchronized void init(ProcessingEnvironment processingEnv) {

        if (initialized)

            throw new IllegalStateException("Cannot call init more than once.");

        if (processingEnv == null)

            throw new NullPointerException("Tool provided null ProcessingEnvironment");

        this.processingEnv = processingEnv;

        initialized = true;

    }

    /**

     * {@inheritDoc}

     */

    public abstract boolean process(Set<? extends TypeElement> annotations,

                                    RoundEnvironment roundEnv);

    /**

     * Returns an empty iterable of completions.

     *

     * @param element {@inheritDoc}

     * @param annotation {@inheritDoc}

     * @param member {@inheritDoc}

     * @param userText {@inheritDoc}

     */

    public Iterable<? extends Completion> getCompletions(Element element,

                                                         AnnotationMirror annotation,

                                                         ExecutableElement member,

                                                         String userText) {

        return Collections.emptyList();

    }

    /**

     * Returns {@code true} if this object has been {@linkplain #init

     * initialized}, {@code false} otherwise.

     *

     * @return {@code true} if this object has been initialized,

     * {@code false} otherwise.

     */

    protected synchronized boolean isInitialized() {

        return initialized;

    }

    private static Set<String> arrayToSet(String[] array) {

        assert array != null;

        Set<String> set = new HashSet<String>(array.length);

        for (String s : array)

            set.add(s);

        return Collections.unmodifiableSet(set);

    }

}