1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/classes/javax/lang/model/util/ElementFilter.java Wed Apr 27 01:34:52 2016 +0800
1.3 @@ -0,0 +1,210 @@
1.4 +/*
1.5 + * Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation. Oracle designates this
1.11 + * particular file as subject to the "Classpath" exception as provided
1.12 + * by Oracle in the LICENSE file that accompanied this code.
1.13 + *
1.14 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 + * version 2 for more details (a copy is included in the LICENSE file that
1.18 + * accompanied this code).
1.19 + *
1.20 + * You should have received a copy of the GNU General Public License version
1.21 + * 2 along with this work; if not, write to the Free Software Foundation,
1.22 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 + *
1.24 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 + * or visit www.oracle.com if you need additional information or have any
1.26 + * questions.
1.27 + */
1.28 +
1.29 +package javax.lang.model.util;
1.30 +
1.31 +import java.util.Collections;
1.32 +import java.util.List;
1.33 +import java.util.Set;
1.34 +import java.util.EnumSet;
1.35 +import java.util.ArrayList;
1.36 +import java.util.LinkedHashSet;
1.37 +
1.38 +import javax.lang.model.element.*;
1.39 +
1.40 +
1.41 +/**
1.42 + * Filters for selecting just the elements of interest from a
1.43 + * collection of elements. The returned sets and lists are new
1.44 + * collections and do use the argument as a backing store. The
1.45 + * methods in this class do not make any attempts to guard against
1.46 + * concurrent modifications of the arguments. The returned sets and
1.47 + * lists are mutable but unsafe for concurrent access. A returned set
1.48 + * has the same iteration order as the argument set to a method.
1.49 + *
1.50 + * <p>If iterables and sets containing {@code null} are passed as
1.51 + * arguments to methods in this class, a {@code NullPointerException}
1.52 + * will be thrown.
1.53 + *
1.54 + * <p>Note that a <i>static import</i> statement can make the text of
1.55 + * calls to the methods in this class more concise; for example:
1.56 + *
1.57 + * <blockquote><pre>
1.58 + * import static javax.lang.model.util.ElementFilter.*;
1.59 + * ...
1.60 + * {@code List<VariableElement>} fs = fieldsIn(someClass.getEnclosedElements());
1.61 + * </pre></blockquote>
1.62 + *
1.63 + * @author Joseph D. Darcy
1.64 + * @author Scott Seligman
1.65 + * @author Peter von der Ahé
1.66 + * @author Martin Buchholz
1.67 + * @since 1.6
1.68 + */
1.69 +public class ElementFilter {
1.70 + private ElementFilter() {} // Do not instantiate.
1.71 +
1.72 + private static final Set<ElementKind> CONSTRUCTOR_KIND =
1.73 + Collections.unmodifiableSet(EnumSet.of(ElementKind.CONSTRUCTOR));
1.74 +
1.75 + private static final Set<ElementKind> FIELD_KINDS =
1.76 + Collections.unmodifiableSet(EnumSet.of(ElementKind.FIELD,
1.77 + ElementKind.ENUM_CONSTANT));
1.78 + private static final Set<ElementKind> METHOD_KIND =
1.79 + Collections.unmodifiableSet(EnumSet.of(ElementKind.METHOD));
1.80 +
1.81 + private static final Set<ElementKind> PACKAGE_KIND =
1.82 + Collections.unmodifiableSet(EnumSet.of(ElementKind.PACKAGE));
1.83 +
1.84 + private static final Set<ElementKind> TYPE_KINDS =
1.85 + Collections.unmodifiableSet(EnumSet.of(ElementKind.CLASS,
1.86 + ElementKind.ENUM,
1.87 + ElementKind.INTERFACE,
1.88 + ElementKind.ANNOTATION_TYPE));
1.89 + /**
1.90 + * Returns a list of fields in {@code elements}.
1.91 + * @return a list of fields in {@code elements}
1.92 + * @param elements the elements to filter
1.93 + */
1.94 + public static List<VariableElement>
1.95 + fieldsIn(Iterable<? extends Element> elements) {
1.96 + return listFilter(elements, FIELD_KINDS, VariableElement.class);
1.97 + }
1.98 +
1.99 + /**
1.100 + * Returns a set of fields in {@code elements}.
1.101 + * @return a set of fields in {@code elements}
1.102 + * @param elements the elements to filter
1.103 + */
1.104 + public static Set<VariableElement>
1.105 + fieldsIn(Set<? extends Element> elements) {
1.106 + return setFilter(elements, FIELD_KINDS, VariableElement.class);
1.107 + }
1.108 +
1.109 + /**
1.110 + * Returns a list of constructors in {@code elements}.
1.111 + * @return a list of constructors in {@code elements}
1.112 + * @param elements the elements to filter
1.113 + */
1.114 + public static List<ExecutableElement>
1.115 + constructorsIn(Iterable<? extends Element> elements) {
1.116 + return listFilter(elements, CONSTRUCTOR_KIND, ExecutableElement.class);
1.117 + }
1.118 +
1.119 + /**
1.120 + * Returns a set of constructors in {@code elements}.
1.121 + * @return a set of constructors in {@code elements}
1.122 + * @param elements the elements to filter
1.123 + */
1.124 + public static Set<ExecutableElement>
1.125 + constructorsIn(Set<? extends Element> elements) {
1.126 + return setFilter(elements, CONSTRUCTOR_KIND, ExecutableElement.class);
1.127 + }
1.128 +
1.129 + /**
1.130 + * Returns a list of methods in {@code elements}.
1.131 + * @return a list of methods in {@code elements}
1.132 + * @param elements the elements to filter
1.133 + */
1.134 + public static List<ExecutableElement>
1.135 + methodsIn(Iterable<? extends Element> elements) {
1.136 + return listFilter(elements, METHOD_KIND, ExecutableElement.class);
1.137 + }
1.138 +
1.139 + /**
1.140 + * Returns a set of methods in {@code elements}.
1.141 + * @return a set of methods in {@code elements}
1.142 + * @param elements the elements to filter
1.143 + */
1.144 + public static Set<ExecutableElement>
1.145 + methodsIn(Set<? extends Element> elements) {
1.146 + return setFilter(elements, METHOD_KIND, ExecutableElement.class);
1.147 + }
1.148 +
1.149 + /**
1.150 + * Returns a list of types in {@code elements}.
1.151 + * @return a list of types in {@code elements}
1.152 + * @param elements the elements to filter
1.153 + */
1.154 + public static List<TypeElement>
1.155 + typesIn(Iterable<? extends Element> elements) {
1.156 + return listFilter(elements, TYPE_KINDS, TypeElement.class);
1.157 + }
1.158 +
1.159 + /**
1.160 + * Returns a set of types in {@code elements}.
1.161 + * @return a set of types in {@code elements}
1.162 + * @param elements the elements to filter
1.163 + */
1.164 + public static Set<TypeElement>
1.165 + typesIn(Set<? extends Element> elements) {
1.166 + return setFilter(elements, TYPE_KINDS, TypeElement.class);
1.167 + }
1.168 +
1.169 + /**
1.170 + * Returns a list of packages in {@code elements}.
1.171 + * @return a list of packages in {@code elements}
1.172 + * @param elements the elements to filter
1.173 + */
1.174 + public static List<PackageElement>
1.175 + packagesIn(Iterable<? extends Element> elements) {
1.176 + return listFilter(elements, PACKAGE_KIND, PackageElement.class);
1.177 + }
1.178 +
1.179 + /**
1.180 + * Returns a set of packages in {@code elements}.
1.181 + * @return a set of packages in {@code elements}
1.182 + * @param elements the elements to filter
1.183 + */
1.184 + public static Set<PackageElement>
1.185 + packagesIn(Set<? extends Element> elements) {
1.186 + return setFilter(elements, PACKAGE_KIND, PackageElement.class);
1.187 + }
1.188 +
1.189 + // Assumes targetKinds and E are sensible.
1.190 + private static <E extends Element> List<E> listFilter(Iterable<? extends Element> elements,
1.191 + Set<ElementKind> targetKinds,
1.192 + Class<E> clazz) {
1.193 + List<E> list = new ArrayList<E>();
1.194 + for (Element e : elements) {
1.195 + if (targetKinds.contains(e.getKind()))
1.196 + list.add(clazz.cast(e));
1.197 + }
1.198 + return list;
1.199 + }
1.200 +
1.201 + // Assumes targetKinds and E are sensible.
1.202 + private static <E extends Element> Set<E> setFilter(Set<? extends Element> elements,
1.203 + Set<ElementKind> targetKinds,
1.204 + Class<E> clazz) {
1.205 + // Return set preserving iteration order of input set.
1.206 + Set<E> set = new LinkedHashSet<E>();
1.207 + for (Element e : elements) {
1.208 + if (targetKinds.contains(e.getKind()))
1.209 + set.add(clazz.cast(e));
1.210 + }
1.211 + return set;
1.212 + }
1.213 +}
