aoqi@0: /*
aoqi@0:  * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.  Oracle designates this
aoqi@0:  * particular file as subject to the "Classpath" exception as provided
aoqi@0:  * by Oracle in the LICENSE file that accompanied this code.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  */
aoqi@0: 
aoqi@0: package com.sun.xml.internal.bind.annotation;
aoqi@0: 
aoqi@0: import java.lang.annotation.Retention;
aoqi@0: import java.lang.annotation.Target;
aoqi@0: 
aoqi@0: import javax.xml.bind.annotation.XmlAttribute;
aoqi@0: import javax.xml.bind.annotation.XmlElement;
aoqi@0: import javax.xml.bind.annotation.XmlElementRef;
aoqi@0: import javax.xml.bind.annotation.XmlValue;
aoqi@0: 
aoqi@0: import static java.lang.annotation.ElementType.FIELD;
aoqi@0: import static java.lang.annotation.ElementType.METHOD;
aoqi@0: import static java.lang.annotation.RetentionPolicy.RUNTIME;
aoqi@0: 
aoqi@0: /**
aoqi@0:  * Designates a boolean field/property as a flag to indicate
aoqi@0:  * whether another property is present or not.
aoqi@0:  *
aoqi@0:  * <p>
aoqi@0:  * Sometimes you'd want to map a Java primitive type to an
aoqi@0:  * optional element/attribute. Doing this makes it impossible
aoqi@0:  * to represent the absence of the property, thus you always
aoqi@0:  * end up producing the value when you marshal to XML.
aoqi@0:  *
aoqi@0:  * For example,
aoqi@0:  * <pre>
aoqi@0:  * {@link XmlElement}
aoqi@0:  * class Foo {
aoqi@0:  *      {@link XmlElement}
aoqi@0:  *      int x;
aoqi@0:  * }
aoqi@0:  *
aoqi@0:  * marshaller.marshal(new Foo());
aoqi@0:  * </pre>
aoqi@0:  * and you get:
aoqi@0:  * <pre><xmp>
aoqi@0:  * <foo><x>0</x></foo>
aoqi@0:  * </xmp></pre>
aoqi@0:  *
aoqi@0:  * <p>
aoqi@0:  * By creating a side boolean field/property that has this annotation,
aoqi@0:  * you can indicate the absence of the property by setting this boolean
aoqi@0:  * to false.
aoqi@0:  * <pre>
aoqi@0:  * {@link XmlElement}
aoqi@0:  * class Foo {
aoqi@0:  *      {@link XmlElement}
aoqi@0:  *      int x;
aoqi@0:  *      {@link XmlIsSet}("x")
aoqi@0:  *      boolean xIsPresent;
aoqi@0:  * }
aoqi@0:  *
aoqi@0:  * Foo f = new Foo();
aoqi@0:  * f.x = 5;
aoqi@0:  * f.xIsPresent = false;
aoqi@0:  *
aoqi@0:  * marshaller.marshal(f);
aoqi@0:  *
aoqi@0:  * <xmp>
aoqi@0:  * <foo/>
aoqi@0:  * </xmp>
aoqi@0:  *
aoqi@0:  * f.xIsPresent = true;
aoqi@0:  * <xmp>
aoqi@0:  * <foo><x>5</x></foo>
aoqi@0:  * </xmp>
aoqi@0:  * </pre>
aoqi@0:  *
aoqi@0:  * <p>
aoqi@0:  * A property/field annotated with {@link XmlIsSet} itself will not show up in XML.
aoqi@0:  * It is an error to use this annotation on the same property/field
aoqi@0:  * as {@link XmlElement}, {@link XmlAttribute}, {@link XmlValue}, or {@link XmlElementRef},
aoqi@0:  * ...<b>TBD</b>.
aoqi@0:  *
aoqi@0:  * @deprecated
aoqi@0:  *      this hasn't been implemented in the RI, and this hasn't been speced yet.
aoqi@0:  *      I believe Joe asked for this feature. I'd like to drop this.
aoqi@0:  *
aoqi@0:  * @author Kohsuke Kawaguchi
aoqi@0:  */
aoqi@0: @Retention(RUNTIME)
aoqi@0: @Target({FIELD,METHOD})
aoqi@0: public @interface XmlIsSet {
aoqi@0:     /**
aoqi@0:      * Specifies the name of the property to attach to.
aoqi@0:      */
aoqi@0:     String value();
aoqi@0: }