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 * 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.

 *

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package jdk.javadoc.internal.doclets.toolkit.taglets;

import javax.lang.model.element.Element;

import javax.lang.model.element.TypeElement;

import javax.lang.model.element.VariableElement;

import javax.lang.model.util.Elements;

import com.sun.source.doctree.DocTree;

import jdk.javadoc.internal.doclets.toolkit.Content;

import jdk.javadoc.internal.doclets.toolkit.Messages;

import jdk.javadoc.internal.doclets.toolkit.util.CommentHelper;

import jdk.javadoc.internal.doclets.toolkit.util.Utils;

import static com.sun.source.doctree.DocTree.Kind.*;

/**

 * An inline Taglet representing the value tag. This tag should only be used with

 * constant fields that have a value.  It is used to access the value of constant

 * fields.  This inline tag has an optional field name parameter.  If the name is

 * specified, the constant value is retrieved from the specified field.  A link

 * is also created to the specified field.  If a name is not specified, the value

 * is retrieved for the field that the inline tag appears on.  The name is specifed

 * in the following format:  [fully qualified class name]#[constant field name].

 *

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 *

 * @author Jamie Ho

 */

public class ValueTaglet extends BaseInlineTaglet {

    /**

     * Construct a new ValueTaglet.

     */

    public ValueTaglet() {

        name = VALUE.tagName;

    }

    /**

     * Will return false because this inline tag may

     * only appear in Fields.

     * @return false since this is not a method.

     */

    public boolean inMethod() {

        return true;

    }

    /**

     * Will return false because this inline tag may

     * only appear in Fields.

     * @return false since this is not a method.

     */

    public boolean inConstructor() {

        return true;

    }

    /**

     * Will return false because this inline tag may

     * only appear in Fields.

     * @return false since this is not a method.

     */

    public boolean inOverview() {

        return true;

    }

    /**

     * Will return false because this inline tag may

     * only appear in Fields.

     * @return false since this is not a field.

     */

    public boolean inModule() {

        return false;

    }

    /**

     * Will return false because this inline tag may

     * only appear in Fields.

     * @return false since this is not a method.

     */

    public boolean inPackage() {

        return true;

    }

    /**

     * Will return false because this inline tag may

     * only appear in Fields.

     * @return false since this is not a method.

     */

    public boolean inType() {

        return true;

    }

    /**

     * Given the name of the field, return the corresponding VariableElement. Return null

     * due to invalid use of value tag if the name is null or empty string and if

     * the value tag is not used on a field.

     *

     * @param holder the element holding the tag

     * @param config the current configuration of the doclet.

     * @param tag the value tag.

     *

     * @return the corresponding VariableElement. If the name is null or empty string,

     * return field that the value tag was used in. Return null if the name is null

     * or empty string and if the value tag is not used on a field.

     */

        Utils utils = config.utils;

        CommentHelper ch = utils.getCommentHelper(holder);

        String signature = ch.getReferencedSignature(tag);

        if (signature == null) { // no reference

            //Base case: no label.

            if (utils.isVariableElement(holder)) {

                return (VariableElement)(holder);

            } else {

                // If the value tag does not specify a parameter which is a valid field and

                // it is not used within the comments of a valid field, return null.

                 return null;

            }

        }

        String[] sigValues = signature.split("#");

        String memberName = null;

        TypeElement te = null;

        if (sigValues.length == 1) {

            //Case 2:  @value in same class.

            if (utils.isExecutableElement(holder) || utils.isVariableElement(holder)) {

                te = utils.getEnclosingTypeElement(holder);

            } else if (utils.isTypeElement(holder)) {

                te = utils.getTopMostContainingTypeElement(holder);

            }

            memberName = sigValues[0];

        } else {

            //Case 3: @value in different class.

            Elements elements = config.docEnv.getElementUtils();

            te = elements.getTypeElement(sigValues[0]);

            memberName = sigValues[1];

        }

        if (te == null) {

            return null;

        }

        for (Element field : utils.getFields(te)) {

            if (utils.getSimpleName(field).equals(memberName)) {

                return (VariableElement)field;

            }

        }

        return null;

    }

    /**

     * {@inheritDoc}

     */

    public Content getTagletOutput(Element holder, DocTree tag, TagletWriter writer) {

        Utils utils = writer.configuration().utils;

        Messages messages = writer.configuration().getMessages();

        VariableElement field = getVariableElement(holder, writer.configuration(), tag);

        if (field == null) {

            if (tag.toString().isEmpty()) {

                //Invalid use of @value

                messages.warning(holder,

                        "doclet.value_tag_invalid_use");

            } else {

                //Reference is unknown.

                messages.warning(holder,

                        "doclet.value_tag_invalid_reference", tag.toString());

            }

        } else if (field.getConstantValue() != null) {

            return writer.valueTagOutput(field,

                utils.constantValueExpresion(field),

                // TODO: investigate and cleanup

                // in the j.l.m world, equals will not be accurate

                // !field.equals(tag.holder())

                !utils.elementsEqual(field, holder)

            );

        } else {

            //Referenced field is not a constant.

            messages.warning(holder,

                "doclet.value_tag_invalid_constant", utils.getSimpleName(field));

        }

        return writer.getOutputInstance();

    }

}