duke@1: /* jjg@1357: * Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved. duke@1: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. duke@1: * duke@1: * This code is free software; you can redistribute it and/or modify it duke@1: * under the terms of the GNU General Public License version 2 only, as ohair@554: * published by the Free Software Foundation. Oracle designates this duke@1: * particular file as subject to the "Classpath" exception as provided ohair@554: * by Oracle in the LICENSE file that accompanied this code. duke@1: * duke@1: * This code is distributed in the hope that it will be useful, but WITHOUT duke@1: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or duke@1: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License duke@1: * version 2 for more details (a copy is included in the LICENSE file that duke@1: * accompanied this code). duke@1: * duke@1: * You should have received a copy of the GNU General Public License version duke@1: * 2 along with this work; if not, write to the Free Software Foundation, duke@1: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. duke@1: * ohair@554: * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA ohair@554: * or visit www.oracle.com if you need additional information or have any ohair@554: * questions. duke@1: */ duke@1: duke@1: package javax.lang.model.util; duke@1: duke@1: import java.util.Collections; duke@1: import java.util.List; duke@1: import java.util.Set; duke@1: import java.util.EnumSet; duke@1: import java.util.ArrayList; duke@1: import java.util.LinkedHashSet; duke@1: duke@1: import javax.lang.model.element.*; duke@1: duke@1: duke@1: /** duke@1: * Filters for selecting just the elements of interest from a duke@1: * collection of elements. The returned sets and lists are new duke@1: * collections and do use the argument as a backing store. The duke@1: * methods in this class do not make any attempts to guard against duke@1: * concurrent modifications of the arguments. The returned sets and duke@1: * lists are mutable but unsafe for concurrent access. A returned set duke@1: * has the same iteration order as the argument set to a method. duke@1: * duke@1: *

If iterables and sets containing {@code null} are passed as duke@1: * arguments to methods in this class, a {@code NullPointerException} duke@1: * will be thrown. duke@1: * duke@1: *

Note that a static import statement can make the text of duke@1: * calls to the methods in this class more concise; for example: duke@1: * duke@1: * 

duke@1:  *     import static javax.lang.model.util.ElementFilter.*;
duke@1:  *     ...
duke@1:  *         {@code List} fs = fieldsIn(someClass.getEnclosedElements());
duke@1:  *
duke@1: * duke@1: * @author Joseph D. Darcy duke@1: * @author Scott Seligman duke@1: * @author Peter von der Ahé duke@1: * @author Martin Buchholz duke@1: * @since 1.6 duke@1: */ duke@1: public class ElementFilter { duke@1: private ElementFilter() {} // Do not instantiate. duke@1: duke@1: private static Set CONSTRUCTOR_KIND = duke@1: Collections.unmodifiableSet(EnumSet.of(ElementKind.CONSTRUCTOR)); duke@1: duke@1: private static Set FIELD_KINDS = duke@1: Collections.unmodifiableSet(EnumSet.of(ElementKind.FIELD, duke@1: ElementKind.ENUM_CONSTANT)); duke@1: private static Set METHOD_KIND = duke@1: Collections.unmodifiableSet(EnumSet.of(ElementKind.METHOD)); duke@1: duke@1: private static Set PACKAGE_KIND = duke@1: Collections.unmodifiableSet(EnumSet.of(ElementKind.PACKAGE)); duke@1: duke@1: private static Set TYPE_KINDS = duke@1: Collections.unmodifiableSet(EnumSet.of(ElementKind.CLASS, duke@1: ElementKind.ENUM, duke@1: ElementKind.INTERFACE, duke@1: ElementKind.ANNOTATION_TYPE)); duke@1: /** duke@1: * Returns a list of fields in {@code elements}. duke@1: * @return a list of fields in {@code elements} duke@1: * @param elements the elements to filter duke@1: */ duke@1: public static List duke@1: fieldsIn(Iterable elements) { duke@1: return listFilter(elements, FIELD_KINDS, VariableElement.class); duke@1: } duke@1: duke@1: /** duke@1: * Returns a set of fields in {@code elements}. duke@1: * @return a set of fields in {@code elements} duke@1: * @param elements the elements to filter duke@1: */ duke@1: public static Set duke@1: fieldsIn(Set elements) { duke@1: return setFilter(elements, FIELD_KINDS, VariableElement.class); duke@1: } duke@1: duke@1: /** duke@1: * Returns a list of constructors in {@code elements}. duke@1: * @return a list of constructors in {@code elements} duke@1: * @param elements the elements to filter duke@1: */ duke@1: public static List duke@1: constructorsIn(Iterable elements) { duke@1: return listFilter(elements, CONSTRUCTOR_KIND, ExecutableElement.class); duke@1: } duke@1: duke@1: /** duke@1: * Returns a set of constructors in {@code elements}. duke@1: * @return a set of constructors in {@code elements} duke@1: * @param elements the elements to filter duke@1: */ duke@1: public static Set duke@1: constructorsIn(Set elements) { duke@1: return setFilter(elements, CONSTRUCTOR_KIND, ExecutableElement.class); duke@1: } duke@1: duke@1: /** duke@1: * Returns a list of methods in {@code elements}. duke@1: * @return a list of methods in {@code elements} duke@1: * @param elements the elements to filter duke@1: */ duke@1: public static List duke@1: methodsIn(Iterable elements) { duke@1: return listFilter(elements, METHOD_KIND, ExecutableElement.class); duke@1: } duke@1: duke@1: /** duke@1: * Returns a set of methods in {@code elements}. duke@1: * @return a set of methods in {@code elements} duke@1: * @param elements the elements to filter duke@1: */ duke@1: public static Set duke@1: methodsIn(Set elements) { duke@1: return setFilter(elements, METHOD_KIND, ExecutableElement.class); duke@1: } duke@1: duke@1: /** duke@1: * Returns a list of types in {@code elements}. duke@1: * @return a list of types in {@code elements} duke@1: * @param elements the elements to filter duke@1: */ duke@1: public static List duke@1: typesIn(Iterable elements) { duke@1: return listFilter(elements, TYPE_KINDS, TypeElement.class); duke@1: } duke@1: duke@1: /** duke@1: * Returns a set of types in {@code elements}. duke@1: * @return a set of types in {@code elements} duke@1: * @param elements the elements to filter duke@1: */ duke@1: public static Set duke@1: typesIn(Set elements) { duke@1: return setFilter(elements, TYPE_KINDS, TypeElement.class); duke@1: } duke@1: duke@1: /** duke@1: * Returns a list of packages in {@code elements}. duke@1: * @return a list of packages in {@code elements} duke@1: * @param elements the elements to filter duke@1: */ duke@1: public static List duke@1: packagesIn(Iterable elements) { duke@1: return listFilter(elements, PACKAGE_KIND, PackageElement.class); duke@1: } duke@1: duke@1: /** duke@1: * Returns a set of packages in {@code elements}. duke@1: * @return a set of packages in {@code elements} duke@1: * @param elements the elements to filter duke@1: */ duke@1: public static Set duke@1: packagesIn(Set elements) { duke@1: return setFilter(elements, PACKAGE_KIND, PackageElement.class); duke@1: } duke@1: duke@1: // Assumes targetKinds and E are sensible. duke@1: private static List listFilter(Iterable elements, duke@1: Set targetKinds, duke@1: Class clazz) { duke@1: List list = new ArrayList(); duke@1: for (Element e : elements) { duke@1: if (targetKinds.contains(e.getKind())) duke@1: list.add(clazz.cast(e)); duke@1: } duke@1: return list; duke@1: } duke@1: duke@1: // Assumes targetKinds and E are sensible. duke@1: private static Set setFilter(Set elements, duke@1: Set targetKinds, duke@1: Class clazz) { duke@1: // Return set preserving iteration order of input set. duke@1: Set set = new LinkedHashSet(); duke@1: for (Element e : elements) { duke@1: if (targetKinds.contains(e.getKind())) duke@1: set.add(clazz.cast(e)); duke@1: } duke@1: return set; duke@1: } duke@1: }