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/* * @(#)ElementFilter.java 1.6 06/08/02 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package javax.lang.model.util; import java.lang.Iterable; import java.util.Collections; import java.util.Iterator; import java.util.List; import java.util.Set; import java.util.EnumSet; import java.util.ArrayList; import java.util.LinkedHashSet; import java.util.NoSuchElementException; import javax.lang.model.element.*; import javax.lang.model.type.*; /** * 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 * @version 1.6 06/08/02 * @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; } }