| 1 | /* |
| 2 | * Copyright 2005-2006 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package javax.lang.model.util; |
| 27 | |
| 28 | import java.lang.Iterable; |
| 29 | import java.util.Collections; |
| 30 | import java.util.Iterator; |
| 31 | import java.util.List; |
| 32 | import java.util.Set; |
| 33 | import java.util.EnumSet; |
| 34 | import java.util.ArrayList; |
| 35 | import java.util.LinkedHashSet; |
| 36 | import java.util.NoSuchElementException; |
| 37 | |
| 38 | import javax.lang.model.element.*; |
| 39 | import javax.lang.model.type.*; |
| 40 | |
| 41 | |
| 42 | /** |
| 43 | * Filters for selecting just the elements of interest from a |
| 44 | * collection of elements. The returned sets and lists are new |
| 45 | * collections and do use the argument as a backing store. The |
| 46 | * methods in this class do not make any attempts to guard against |
| 47 | * concurrent modifications of the arguments. The returned sets and |
| 48 | * lists are mutable but unsafe for concurrent access. A returned set |
| 49 | * has the same iteration order as the argument set to a method. |
| 50 | * |
| 51 | * <p>If iterables and sets containing {@code null} are passed as |
| 52 | * arguments to methods in this class, a {@code NullPointerException} |
| 53 | * will be thrown. |
| 54 | * |
| 55 | * <p>Note that a <i>static import</i> statement can make the text of |
| 56 | * calls to the methods in this class more concise; for example: |
| 57 | * |
| 58 | * <blockquote><pre> |
| 59 | * import static javax.lang.model.util.ElementFilter.*; |
| 60 | * ... |
| 61 | * {@code List<VariableElement>} fs = fieldsIn(someClass.getEnclosedElements()); |
| 62 | * </pre></blockquote> |
| 63 | * |
| 64 | * @author Joseph D. Darcy |
| 65 | * @author Scott Seligman |
| 66 | * @author Peter von der Ahé |
| 67 | * @author Martin Buchholz |
| 68 | * @since 1.6 |
| 69 | */ |
| 70 | public class ElementFilter { |
| 71 | private ElementFilter() {} // Do not instantiate. |
| 72 | |
| 73 | private static Set<ElementKind> CONSTRUCTOR_KIND = |
| 74 | Collections.unmodifiableSet(EnumSet.of(ElementKind.CONSTRUCTOR)); |
| 75 | |
| 76 | private static Set<ElementKind> FIELD_KINDS = |
| 77 | Collections.unmodifiableSet(EnumSet.of(ElementKind.FIELD, |
| 78 | ElementKind.ENUM_CONSTANT)); |
| 79 | private static Set<ElementKind> METHOD_KIND = |
| 80 | Collections.unmodifiableSet(EnumSet.of(ElementKind.METHOD)); |
| 81 | |
| 82 | private static Set<ElementKind> PACKAGE_KIND = |
| 83 | Collections.unmodifiableSet(EnumSet.of(ElementKind.PACKAGE)); |
| 84 | |
| 85 | private static Set<ElementKind> TYPE_KINDS = |
| 86 | Collections.unmodifiableSet(EnumSet.of(ElementKind.CLASS, |
| 87 | ElementKind.ENUM, |
| 88 | ElementKind.INTERFACE, |
| 89 | ElementKind.ANNOTATION_TYPE)); |
| 90 | /** |
| 91 | * Returns a list of fields in {@code elements}. |
| 92 | * @return a list of fields in {@code elements} |
| 93 | * @param elements the elements to filter |
| 94 | */ |
| 95 | public static List<VariableElement> |
| 96 | fieldsIn(Iterable<? extends Element> elements) { |
| 97 | return listFilter(elements, FIELD_KINDS, VariableElement.class); |
| 98 | } |
| 99 | |
| 100 | /** |
| 101 | * Returns a set of fields in {@code elements}. |
| 102 | * @return a set of fields in {@code elements} |
| 103 | * @param elements the elements to filter |
| 104 | */ |
| 105 | public static Set<VariableElement> |
| 106 | fieldsIn(Set<? extends Element> elements) { |
| 107 | return setFilter(elements, FIELD_KINDS, VariableElement.class); |
| 108 | } |
| 109 | |
| 110 | /** |
| 111 | * Returns a list of constructors in {@code elements}. |
| 112 | * @return a list of constructors in {@code elements} |
| 113 | * @param elements the elements to filter |
| 114 | */ |
| 115 | public static List<ExecutableElement> |
| 116 | constructorsIn(Iterable<? extends Element> elements) { |
| 117 | return listFilter(elements, CONSTRUCTOR_KIND, ExecutableElement.class); |
| 118 | } |
| 119 | |
| 120 | /** |
| 121 | * Returns a set of constructors in {@code elements}. |
| 122 | * @return a set of constructors in {@code elements} |
| 123 | * @param elements the elements to filter |
| 124 | */ |
| 125 | public static Set<ExecutableElement> |
| 126 | constructorsIn(Set<? extends Element> elements) { |
| 127 | return setFilter(elements, CONSTRUCTOR_KIND, ExecutableElement.class); |
| 128 | } |
| 129 | |
| 130 | /** |
| 131 | * Returns a list of methods in {@code elements}. |
| 132 | * @return a list of methods in {@code elements} |
| 133 | * @param elements the elements to filter |
| 134 | */ |
| 135 | public static List<ExecutableElement> |
| 136 | methodsIn(Iterable<? extends Element> elements) { |
| 137 | return listFilter(elements, METHOD_KIND, ExecutableElement.class); |
| 138 | } |
| 139 | |
| 140 | /** |
| 141 | * Returns a set of methods in {@code elements}. |
| 142 | * @return a set of methods in {@code elements} |
| 143 | * @param elements the elements to filter |
| 144 | */ |
| 145 | public static Set<ExecutableElement> |
| 146 | methodsIn(Set<? extends Element> elements) { |
| 147 | return setFilter(elements, METHOD_KIND, ExecutableElement.class); |
| 148 | } |
| 149 | |
| 150 | /** |
| 151 | * Returns a list of types in {@code elements}. |
| 152 | * @return a list of types in {@code elements} |
| 153 | * @param elements the elements to filter |
| 154 | */ |
| 155 | public static List<TypeElement> |
| 156 | typesIn(Iterable<? extends Element> elements) { |
| 157 | return listFilter(elements, TYPE_KINDS, TypeElement.class); |
| 158 | } |
| 159 | |
| 160 | /** |
| 161 | * Returns a set of types in {@code elements}. |
| 162 | * @return a set of types in {@code elements} |
| 163 | * @param elements the elements to filter |
| 164 | */ |
| 165 | public static Set<TypeElement> |
| 166 | typesIn(Set<? extends Element> elements) { |
| 167 | return setFilter(elements, TYPE_KINDS, TypeElement.class); |
| 168 | } |
| 169 | |
| 170 | /** |
| 171 | * Returns a list of packages in {@code elements}. |
| 172 | * @return a list of packages in {@code elements} |
| 173 | * @param elements the elements to filter |
| 174 | */ |
| 175 | public static List<PackageElement> |
| 176 | packagesIn(Iterable<? extends Element> elements) { |
| 177 | return listFilter(elements, PACKAGE_KIND, PackageElement.class); |
| 178 | } |
| 179 | |
| 180 | /** |
| 181 | * Returns a set of packages in {@code elements}. |
| 182 | * @return a set of packages in {@code elements} |
| 183 | * @param elements the elements to filter |
| 184 | */ |
| 185 | public static Set<PackageElement> |
| 186 | packagesIn(Set<? extends Element> elements) { |
| 187 | return setFilter(elements, PACKAGE_KIND, PackageElement.class); |
| 188 | } |
| 189 | |
| 190 | // Assumes targetKinds and E are sensible. |
| 191 | private static <E extends Element> List<E> listFilter(Iterable<? extends Element> elements, |
| 192 | Set<ElementKind> targetKinds, |
| 193 | Class<E> clazz) { |
| 194 | List<E> list = new ArrayList<E>(); |
| 195 | for (Element e : elements) { |
| 196 | if (targetKinds.contains(e.getKind())) |
| 197 | list.add(clazz.cast(e)); |
| 198 | } |
| 199 | return list; |
| 200 | } |
| 201 | |
| 202 | // Assumes targetKinds and E are sensible. |
| 203 | private static <E extends Element> Set<E> setFilter(Set<? extends Element> elements, |
| 204 | Set<ElementKind> targetKinds, |
| 205 | Class<E> clazz) { |
| 206 | // Return set preserving iteration order of input set. |
| 207 | Set<E> set = new LinkedHashSet<E>(); |
| 208 | for (Element e : elements) { |
| 209 | if (targetKinds.contains(e.getKind())) |
| 210 | set.add(clazz.cast(e)); |
| 211 | } |
| 212 | return set; |
| 213 | } |
| 214 | } |