Mercurial > jdk8-mips64-public > langtools / file revision

 /*

  * Copyright (c) 2005, 2012, 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

  * or visit www.oracle.com if you need additional information or have any

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  */

 package javax.lang.model.util;

 import java.util.Collections;

 import java.util.List;

 import java.util.Set;

 import java.util.EnumSet;

 import java.util.ArrayList;

 import java.util.LinkedHashSet;

 import javax.lang.model.element.*;

 /**

  * Filters for selecting just the elements of interest from a

  * collection of elements.  The returned sets and lists are new

  * collections and do use the argument as a backing store.  The

  * methods in this class do not make any attempts to guard against

  * concurrent modifications of the arguments.  The returned sets and

  * lists are mutable but unsafe for concurrent access.  A returned set

  * has the same iteration order as the argument set to a method.

  *

  * <p>If iterables and sets containing {@code null} are passed as

  * arguments to methods in this class, a {@code NullPointerException}

  * will be thrown.

  *

  * <p>Note that a <i>static import</i> statement can make the text of

  * calls to the methods in this class more concise; for example:

  *

  * <blockquote><pre>

  *     import static javax.lang.model.util.ElementFilter.*;

  *     ...

  *         {@code List<VariableElement>} fs = fieldsIn(someClass.getEnclosedElements());

  * </pre></blockquote>

  *

  * @author Joseph D. Darcy

  * @author Scott Seligman

  * @author Peter von der Ahé

  * @author Martin Buchholz

  * @since 1.6

  */

 public class ElementFilter {

     private ElementFilter() {} // Do not instantiate.

     private static Set<ElementKind> CONSTRUCTOR_KIND =

         Collections.unmodifiableSet(EnumSet.of(ElementKind.CONSTRUCTOR));

     private static Set<ElementKind> FIELD_KINDS =

         Collections.unmodifiableSet(EnumSet.of(ElementKind.FIELD,

                                                ElementKind.ENUM_CONSTANT));

     private static Set<ElementKind> METHOD_KIND =

         Collections.unmodifiableSet(EnumSet.of(ElementKind.METHOD));

     private static Set<ElementKind> PACKAGE_KIND =

         Collections.unmodifiableSet(EnumSet.of(ElementKind.PACKAGE));

     private static Set<ElementKind> TYPE_KINDS =

         Collections.unmodifiableSet(EnumSet.of(ElementKind.CLASS,

                                                ElementKind.ENUM,

                                                ElementKind.INTERFACE,

                                                ElementKind.ANNOTATION_TYPE));

     /**

      * Returns a list of fields in {@code elements}.

      * @return a list of fields in {@code elements}

      * @param elements the elements to filter

      */

     public static List<VariableElement>

             fieldsIn(Iterable<? extends Element> elements) {

         return listFilter(elements, FIELD_KINDS, VariableElement.class);

     }

     /**

      * Returns a set of fields in {@code elements}.

      * @return a set of fields in {@code elements}

      * @param elements the elements to filter

      */

     public static Set<VariableElement>

             fieldsIn(Set<? extends Element> elements) {

         return setFilter(elements, FIELD_KINDS, VariableElement.class);

     }

     /**

      * Returns a list of constructors in {@code elements}.

      * @return a list of constructors in {@code elements}

      * @param elements the elements to filter

      */

     public static List<ExecutableElement>

             constructorsIn(Iterable<? extends Element> elements) {

         return listFilter(elements, CONSTRUCTOR_KIND, ExecutableElement.class);

     }

     /**

      * Returns a set of constructors in {@code elements}.

      * @return a set of constructors in {@code elements}

      * @param elements the elements to filter

      */

     public static Set<ExecutableElement>

             constructorsIn(Set<? extends Element> elements) {

         return setFilter(elements, CONSTRUCTOR_KIND, ExecutableElement.class);

     }

     /**

      * Returns a list of methods in {@code elements}.

      * @return a list of methods in {@code elements}

      * @param elements the elements to filter

      */

     public static List<ExecutableElement>

             methodsIn(Iterable<? extends Element> elements) {

         return listFilter(elements, METHOD_KIND, ExecutableElement.class);

     }

     /**

      * Returns a set of methods in {@code elements}.

      * @return a set of methods in {@code elements}

      * @param elements the elements to filter

      */

     public static Set<ExecutableElement>

             methodsIn(Set<? extends Element> elements) {

         return setFilter(elements, METHOD_KIND, ExecutableElement.class);

     }

     /**

      * Returns a list of types in {@code elements}.

      * @return a list of types in {@code elements}

      * @param elements the elements to filter

      */

     public static List<TypeElement>

             typesIn(Iterable<? extends Element> elements) {

         return listFilter(elements, TYPE_KINDS, TypeElement.class);

     }

     /**

      * Returns a set of types in {@code elements}.

      * @return a set of types in {@code elements}

      * @param elements the elements to filter

      */

     public static Set<TypeElement>

             typesIn(Set<? extends Element> elements) {

         return setFilter(elements, TYPE_KINDS, TypeElement.class);

     }

     /**

      * Returns a list of packages in {@code elements}.

      * @return a list of packages in {@code elements}

      * @param elements the elements to filter

      */

     public static List<PackageElement>

             packagesIn(Iterable<? extends Element> elements) {

         return listFilter(elements, PACKAGE_KIND, PackageElement.class);

     }

     /**

      * Returns a set of packages in {@code elements}.

      * @return a set of packages in {@code elements}

      * @param elements the elements to filter

      */

     public static Set<PackageElement>

             packagesIn(Set<? extends Element> elements) {

         return setFilter(elements, PACKAGE_KIND, PackageElement.class);

     }

     // Assumes targetKinds and E are sensible.

     private static <E extends Element> List<E> listFilter(Iterable<? extends Element> elements,

                                                           Set<ElementKind> targetKinds,

                                                           Class<E> clazz) {

         List<E> list = new ArrayList<E>();

         for (Element e : elements) {

             if (targetKinds.contains(e.getKind()))

                 list.add(clazz.cast(e));

         }

         return list;

     }

     // Assumes targetKinds and E are sensible.

     private static <E extends Element> Set<E> setFilter(Set<? extends Element> elements,

                                                         Set<ElementKind> targetKinds,

                                                         Class<E> clazz) {

         // Return set preserving iteration order of input set.

         Set<E> set = new LinkedHashSet<E>();

         for (Element e : elements) {

             if (targetKinds.contains(e.getKind()))

                 set.add(clazz.cast(e));

         }

         return set;

     }

 }