| // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package com.google.dart.compiler.util.apache; |
| |
| import com.google.dart.compiler.util.apache.exception.CloneFailedException; |
| import com.google.dart.compiler.util.apache.mutable.MutableInt; |
| |
| import java.io.Serializable; |
| import java.lang.reflect.Array; |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.util.Collections; |
| import java.util.Comparator; |
| import java.util.HashMap; |
| import java.util.Map; |
| import java.util.TreeSet; |
| |
| /** |
| * <p>Operations on {@code Object}.</p> |
| * |
| * <p>This class tries to handle {@code null} input gracefully. |
| * An exception will generally not be thrown for a {@code null} input. |
| * Each method documents its behaviour in more detail.</p> |
| * <p> |
| * NOTICE: This file is modified copy of its original Apache library. |
| * It was moved to the different package, and changed to reduce number of dependencies. |
| * |
| * <p>#ThreadSafe#</p> |
| * @since 1.0 |
| * @version $Id: ObjectUtils.java 1199894 2011-11-09 17:53:59Z ggregory $ |
| */ |
| //@Immutable |
| public class ObjectUtils { |
| |
| /** |
| * <p>Singleton used as a {@code null} placeholder where |
| * {@code null} has another meaning.</p> |
| * |
| * <p>For example, in a {@code HashMap} the |
| * {@link java.util.HashMap#get(java.lang.Object)} method returns |
| * {@code null} if the {@code Map} contains {@code null} or if there |
| * is no matching key. The {@code Null} placeholder can be used to |
| * distinguish between these two cases.</p> |
| * |
| * <p>Another example is {@code Hashtable}, where {@code null} |
| * cannot be stored.</p> |
| * |
| * <p>This instance is Serializable.</p> |
| */ |
| public static final Null NULL = new Null(); |
| |
| /** |
| * <p>{@code ObjectUtils} instances should NOT be constructed in |
| * standard programming. Instead, the static methods on the class should |
| * be used, such as {@code ObjectUtils.defaultIfNull("a","b");}.</p> |
| * |
| * <p>This constructor is public to permit tools that require a JavaBean |
| * instance to operate.</p> |
| */ |
| public ObjectUtils() { |
| super(); |
| } |
| |
| // Defaulting |
| //----------------------------------------------------------------------- |
| /** |
| * <p>Returns a default value if the object passed is {@code null}.</p> |
| * |
| * <pre> |
| * ObjectUtils.defaultIfNull(null, null) = null |
| * ObjectUtils.defaultIfNull(null, "") = "" |
| * ObjectUtils.defaultIfNull(null, "zz") = "zz" |
| * ObjectUtils.defaultIfNull("abc", *) = "abc" |
| * ObjectUtils.defaultIfNull(Boolean.TRUE, *) = Boolean.TRUE |
| * </pre> |
| * |
| * @param <T> the type of the object |
| * @param object the {@code Object} to test, may be {@code null} |
| * @param defaultValue the default value to return, may be {@code null} |
| * @return {@code object} if it is not {@code null}, defaultValue otherwise |
| */ |
| public static <T> T defaultIfNull(T object, T defaultValue) { |
| return object != null ? object : defaultValue; |
| } |
| |
| /** |
| * <p>Returns the first value in the array which is not {@code null}. |
| * If all the values are {@code null} or the array is {@code null} |
| * or empty then {@code null} is returned.</p> |
| * |
| * <pre> |
| * ObjectUtils.firstNonNull(null, null) = null |
| * ObjectUtils.firstNonNull(null, "") = "" |
| * ObjectUtils.firstNonNull(null, null, "") = "" |
| * ObjectUtils.firstNonNull(null, "zz") = "zz" |
| * ObjectUtils.firstNonNull("abc", *) = "abc" |
| * ObjectUtils.firstNonNull(null, "xyz", *) = "xyz" |
| * ObjectUtils.firstNonNull(Boolean.TRUE, *) = Boolean.TRUE |
| * ObjectUtils.firstNonNull() = null |
| * </pre> |
| * |
| * @param <T> the component type of the array |
| * @param values the values to test, may be {@code null} or empty |
| * @return the first value from {@code values} which is not {@code null}, |
| * or {@code null} if there are no non-null values |
| * @since 3.0 |
| */ |
| public static <T> T firstNonNull(T... values) { |
| if (values != null) { |
| for (T val : values) { |
| if (val != null) { |
| return val; |
| } |
| } |
| } |
| return null; |
| } |
| |
| // Null-safe equals/hashCode |
| //----------------------------------------------------------------------- |
| /** |
| * <p>Compares two objects for equality, where either one or both |
| * objects may be {@code null}.</p> |
| * |
| * <pre> |
| * ObjectUtils.equals(null, null) = true |
| * ObjectUtils.equals(null, "") = false |
| * ObjectUtils.equals("", null) = false |
| * ObjectUtils.equals("", "") = true |
| * ObjectUtils.equals(Boolean.TRUE, null) = false |
| * ObjectUtils.equals(Boolean.TRUE, "true") = false |
| * ObjectUtils.equals(Boolean.TRUE, Boolean.TRUE) = true |
| * ObjectUtils.equals(Boolean.TRUE, Boolean.FALSE) = false |
| * </pre> |
| * |
| * @param object1 the first object, may be {@code null} |
| * @param object2 the second object, may be {@code null} |
| * @return {@code true} if the values of both objects are the same |
| */ |
| public static boolean equals(Object object1, Object object2) { |
| if (object1 == object2) { |
| return true; |
| } |
| if (object1 == null || object2 == null) { |
| return false; |
| } |
| return object1.equals(object2); |
| } |
| |
| /** |
| * <p>Compares two objects for inequality, where either one or both |
| * objects may be {@code null}.</p> |
| * |
| * <pre> |
| * ObjectUtils.notEqual(null, null) = false |
| * ObjectUtils.notEqual(null, "") = true |
| * ObjectUtils.notEqual("", null) = true |
| * ObjectUtils.notEqual("", "") = false |
| * ObjectUtils.notEqual(Boolean.TRUE, null) = true |
| * ObjectUtils.notEqual(Boolean.TRUE, "true") = true |
| * ObjectUtils.notEqual(Boolean.TRUE, Boolean.TRUE) = false |
| * ObjectUtils.notEqual(Boolean.TRUE, Boolean.FALSE) = true |
| * </pre> |
| * |
| * @param object1 the first object, may be {@code null} |
| * @param object2 the second object, may be {@code null} |
| * @return {@code false} if the values of both objects are the same |
| */ |
| public static boolean notEqual(Object object1, Object object2) { |
| return ObjectUtils.equals(object1, object2) == false; |
| } |
| |
| /** |
| * <p>Gets the hash code of an object returning zero when the |
| * object is {@code null}.</p> |
| * |
| * <pre> |
| * ObjectUtils.hashCode(null) = 0 |
| * ObjectUtils.hashCode(obj) = obj.hashCode() |
| * </pre> |
| * |
| * @param obj the object to obtain the hash code of, may be {@code null} |
| * @return the hash code of the object, or zero if null |
| * @since 2.1 |
| */ |
| public static int hashCode(Object obj) { |
| // hashCode(Object) retained for performance, as hash code is often critical |
| return obj == null ? 0 : obj.hashCode(); |
| } |
| |
| /** |
| * <p>Gets the hash code for multiple objects.</p> |
| * |
| * <p>This allows a hash code to be rapidly calculated for a number of objects. |
| * The hash code for a single object is the <em>not</em> same as {@link #hashCode(Object)}. |
| * The hash code for multiple objects is the same as that calculated by an |
| * {@code ArrayList} containing the specified objects.</p> |
| * |
| * <pre> |
| * ObjectUtils.hashCodeMulti() = 1 |
| * ObjectUtils.hashCodeMulti((Object[]) null) = 1 |
| * ObjectUtils.hashCodeMulti(a) = 31 + a.hashCode() |
| * ObjectUtils.hashCodeMulti(a,b) = (31 + a.hashCode()) * 31 + b.hashCode() |
| * ObjectUtils.hashCodeMulti(a,b,c) = ((31 + a.hashCode()) * 31 + b.hashCode()) * 31 + c.hashCode() |
| * </pre> |
| * |
| * @param objects the objects to obtain the hash code of, may be {@code null} |
| * @return the hash code of the objects, or zero if null |
| * @since 3.0 |
| */ |
| public static int hashCodeMulti(Object... objects) { |
| int hash = 1; |
| if (objects != null) { |
| for (Object object : objects) { |
| hash = hash * 31 + ObjectUtils.hashCode(object); |
| } |
| } |
| return hash; |
| } |
| |
| // Identity ToString |
| //----------------------------------------------------------------------- |
| /** |
| * <p>Gets the toString that would be produced by {@code Object} |
| * if a class did not override toString itself. {@code null} |
| * will return {@code null}.</p> |
| * |
| * <pre> |
| * ObjectUtils.identityToString(null) = null |
| * ObjectUtils.identityToString("") = "java.lang.String@1e23" |
| * ObjectUtils.identityToString(Boolean.TRUE) = "java.lang.Boolean@7fa" |
| * </pre> |
| * |
| * @param object the object to create a toString for, may be |
| * {@code null} |
| * @return the default toString text, or {@code null} if |
| * {@code null} passed in |
| */ |
| public static String identityToString(Object object) { |
| if (object == null) { |
| return null; |
| } |
| StringBuffer buffer = new StringBuffer(); |
| identityToString(buffer, object); |
| return buffer.toString(); |
| } |
| |
| /** |
| * <p>Appends the toString that would be produced by {@code Object} |
| * if a class did not override toString itself. {@code null} |
| * will throw a NullPointerException for either of the two parameters. </p> |
| * |
| * <pre> |
| * ObjectUtils.identityToString(buf, "") = buf.append("java.lang.String@1e23" |
| * ObjectUtils.identityToString(buf, Boolean.TRUE) = buf.append("java.lang.Boolean@7fa" |
| * ObjectUtils.identityToString(buf, Boolean.TRUE) = buf.append("java.lang.Boolean@7fa") |
| * </pre> |
| * |
| * @param buffer the buffer to append to |
| * @param object the object to create a toString for |
| * @since 2.4 |
| */ |
| public static void identityToString(StringBuffer buffer, Object object) { |
| if (object == null) { |
| throw new NullPointerException("Cannot get the toString of a null identity"); |
| } |
| buffer.append(object.getClass().getName()) |
| .append('@') |
| .append(Integer.toHexString(System.identityHashCode(object))); |
| } |
| |
| // ToString |
| //----------------------------------------------------------------------- |
| /** |
| * <p>Gets the {@code toString} of an {@code Object} returning |
| * an empty string ("") if {@code null} input.</p> |
| * |
| * <pre> |
| * ObjectUtils.toString(null) = "" |
| * ObjectUtils.toString("") = "" |
| * ObjectUtils.toString("bat") = "bat" |
| * ObjectUtils.toString(Boolean.TRUE) = "true" |
| * </pre> |
| * |
| * @see StringUtils#defaultString(String) |
| * @see String#valueOf(Object) |
| * @param obj the Object to {@code toString}, may be null |
| * @return the passed in Object's toString, or nullStr if {@code null} input |
| * @since 2.0 |
| */ |
| public static String toString(Object obj) { |
| return obj == null ? "" : obj.toString(); |
| } |
| |
| /** |
| * <p>Gets the {@code toString} of an {@code Object} returning |
| * a specified text if {@code null} input.</p> |
| * |
| * <pre> |
| * ObjectUtils.toString(null, null) = null |
| * ObjectUtils.toString(null, "null") = "null" |
| * ObjectUtils.toString("", "null") = "" |
| * ObjectUtils.toString("bat", "null") = "bat" |
| * ObjectUtils.toString(Boolean.TRUE, "null") = "true" |
| * </pre> |
| * |
| * @see StringUtils#defaultString(String,String) |
| * @see String#valueOf(Object) |
| * @param obj the Object to {@code toString}, may be null |
| * @param nullStr the String to return if {@code null} input, may be null |
| * @return the passed in Object's toString, or nullStr if {@code null} input |
| * @since 2.0 |
| */ |
| public static String toString(Object obj, String nullStr) { |
| return obj == null ? nullStr : obj.toString(); |
| } |
| |
| // Comparable |
| //----------------------------------------------------------------------- |
| /** |
| * <p>Null safe comparison of Comparables.</p> |
| * |
| * @param <T> type of the values processed by this method |
| * @param values the set of comparable values, may be null |
| * @return |
| * <ul> |
| * <li>If any objects are non-null and unequal, the lesser object. |
| * <li>If all objects are non-null and equal, the first. |
| * <li>If any of the comparables are null, the lesser of the non-null objects. |
| * <li>If all the comparables are null, null is returned. |
| * </ul> |
| */ |
| public static <T extends Comparable<? super T>> T min(T... values) { |
| T result = null; |
| if (values != null) { |
| for (T value : values) { |
| if (compare(value, result, true) < 0) { |
| result = value; |
| } |
| } |
| } |
| return result; |
| } |
| |
| /** |
| * <p>Null safe comparison of Comparables.</p> |
| * |
| * @param <T> type of the values processed by this method |
| * @param values the set of comparable values, may be null |
| * @return |
| * <ul> |
| * <li>If any objects are non-null and unequal, the greater object. |
| * <li>If all objects are non-null and equal, the first. |
| * <li>If any of the comparables are null, the greater of the non-null objects. |
| * <li>If all the comparables are null, null is returned. |
| * </ul> |
| */ |
| public static <T extends Comparable<? super T>> T max(T... values) { |
| T result = null; |
| if (values != null) { |
| for (T value : values) { |
| if (compare(value, result, false) > 0) { |
| result = value; |
| } |
| } |
| } |
| return result; |
| } |
| |
| /** |
| * <p>Null safe comparison of Comparables. |
| * {@code null} is assumed to be less than a non-{@code null} value.</p> |
| * |
| * @param <T> type of the values processed by this method |
| * @param c1 the first comparable, may be null |
| * @param c2 the second comparable, may be null |
| * @return a negative value if c1 < c2, zero if c1 = c2 |
| * and a positive value if c1 > c2 |
| */ |
| public static <T extends Comparable<? super T>> int compare(T c1, T c2) { |
| return compare(c1, c2, false); |
| } |
| |
| /** |
| * <p>Null safe comparison of Comparables.</p> |
| * |
| * @param <T> type of the values processed by this method |
| * @param c1 the first comparable, may be null |
| * @param c2 the second comparable, may be null |
| * @param nullGreater if true {@code null} is considered greater |
| * than a non-{@code null} value or if false {@code null} is |
| * considered less than a Non-{@code null} value |
| * @return a negative value if c1 < c2, zero if c1 = c2 |
| * and a positive value if c1 > c2 |
| * @see java.util.Comparator#compare(Object, Object) |
| */ |
| public static <T extends Comparable<? super T>> int compare(T c1, T c2, boolean nullGreater) { |
| if (c1 == c2) { |
| return 0; |
| } else if (c1 == null) { |
| return nullGreater ? 1 : -1; |
| } else if (c2 == null) { |
| return nullGreater ? -1 : 1; |
| } |
| return c1.compareTo(c2); |
| } |
| |
| /** |
| * Find the "best guess" middle value among comparables. If there is an even |
| * number of total values, the lower of the two middle values will be returned. |
| * @param <T> type of values processed by this method |
| * @param items to compare |
| * @return T at middle position |
| * @throws NullPointerException if items is {@code null} |
| * @throws IllegalArgumentException if items is empty or contains {@code null} values |
| * @since 3.0.1 |
| */ |
| public static <T extends Comparable<? super T>> T median(T... items) { |
| // Validate.notEmpty(items); |
| // Validate.noNullElements(items); |
| TreeSet<T> sort = new TreeSet<T>(); |
| Collections.addAll(sort, items); |
| @SuppressWarnings("unchecked") //we know all items added were T instances |
| T result = (T) sort.toArray()[(sort.size() - 1) / 2]; |
| return result; |
| } |
| |
| /** |
| * Find the "best guess" middle value among comparables. If there is an even |
| * number of total values, the lower of the two middle values will be returned. |
| * @param <T> type of values processed by this method |
| * @param comparator to use for comparisons |
| * @param items to compare |
| * @return T at middle position |
| * @throws NullPointerException if items or comparator is {@code null} |
| * @throws IllegalArgumentException if items is empty or contains {@code null} values |
| * @since 3.0.1 |
| */ |
| public static <T> T median(Comparator<T> comparator, T... items) { |
| // Validate.notEmpty(items, "null/empty items"); |
| // Validate.noNullElements(items); |
| // Validate.notNull(comparator, "null comparator"); |
| TreeSet<T> sort = new TreeSet<T>(comparator); |
| Collections.addAll(sort, items); |
| @SuppressWarnings("unchecked") //we know all items added were T instances |
| T result = (T) sort.toArray()[(sort.size() - 1) / 2]; |
| return result; |
| } |
| |
| // Mode |
| //----------------------------------------------------------------------- |
| /** |
| * Find the most frequently occurring item. |
| * |
| * @param <T> type of values processed by this method |
| * @param items to check |
| * @return most populous T, {@code null} if non-unique or no items supplied |
| * @since 3.0.1 |
| */ |
| public static <T> T mode(T... items) { |
| if (ArrayUtils.isNotEmpty(items)) { |
| HashMap<T, MutableInt> occurrences = new HashMap<T, MutableInt>(items.length); |
| for (T t : items) { |
| MutableInt count = occurrences.get(t); |
| if (count == null) { |
| occurrences.put(t, new MutableInt(1)); |
| } else { |
| count.increment(); |
| } |
| } |
| T result = null; |
| int max = 0; |
| for (Map.Entry<T, MutableInt> e : occurrences.entrySet()) { |
| int cmp = e.getValue().intValue(); |
| if (cmp == max) { |
| result = null; |
| } else if (cmp > max) { |
| max = cmp; |
| result = e.getKey(); |
| } |
| } |
| return result; |
| } |
| return null; |
| } |
| |
| // cloning |
| //----------------------------------------------------------------------- |
| /** |
| * <p>Clone an object.</p> |
| * |
| * @param <T> the type of the object |
| * @param obj the object to clone, null returns null |
| * @return the clone if the object implements {@link Cloneable} otherwise {@code null} |
| * @throws CloneFailedException if the object is cloneable and the clone operation fails |
| * @since 3.0 |
| */ |
| public static <T> T clone(final T obj) { |
| if (obj instanceof Cloneable) { |
| final Object result; |
| if (obj.getClass().isArray()) { |
| final Class<?> componentType = obj.getClass().getComponentType(); |
| if (!componentType.isPrimitive()) { |
| result = ((Object[]) obj).clone(); |
| } else { |
| int length = Array.getLength(obj); |
| result = Array.newInstance(componentType, length); |
| while (length-- > 0) { |
| Array.set(result, length, Array.get(obj, length)); |
| } |
| } |
| } else { |
| try { |
| final Method clone = obj.getClass().getMethod("clone"); |
| result = clone.invoke(obj); |
| } catch (final NoSuchMethodException e) { |
| throw new CloneFailedException("Cloneable type " |
| + obj.getClass().getName() |
| + " has no clone method", e); |
| } catch (final IllegalAccessException e) { |
| throw new CloneFailedException("Cannot clone Cloneable type " |
| + obj.getClass().getName(), e); |
| } catch (final InvocationTargetException e) { |
| throw new CloneFailedException("Exception cloning Cloneable type " |
| + obj.getClass().getName(), e.getCause()); |
| } |
| } |
| @SuppressWarnings("unchecked") |
| final T checked = (T) result; |
| return checked; |
| } |
| |
| return null; |
| } |
| |
| /** |
| * <p>Clone an object if possible.</p> |
| * |
| * <p>This method is similar to {@link #clone(Object)}, but will return the provided |
| * instance as the return value instead of {@code null} if the instance |
| * is not cloneable. This is more convenient if the caller uses different |
| * implementations (e.g. of a service) and some of the implementations do not allow concurrent |
| * processing or have state. In such cases the implementation can simply provide a proper |
| * clone implementation and the caller's code does not have to change.</p> |
| * |
| * @param <T> the type of the object |
| * @param obj the object to clone, null returns null |
| * @return the clone if the object implements {@link Cloneable} otherwise the object itself |
| * @throws CloneFailedException if the object is cloneable and the clone operation fails |
| * @since 3.0 |
| */ |
| public static <T> T cloneIfPossible(final T obj) { |
| final T clone = clone(obj); |
| return clone == null ? obj : clone; |
| } |
| |
| // Null |
| //----------------------------------------------------------------------- |
| /** |
| * <p>Class used as a null placeholder where {@code null} |
| * has another meaning.</p> |
| * |
| * <p>For example, in a {@code HashMap} the |
| * {@link java.util.HashMap#get(java.lang.Object)} method returns |
| * {@code null} if the {@code Map} contains {@code null} or if there is |
| * no matching key. The {@code Null} placeholder can be used to distinguish |
| * between these two cases.</p> |
| * |
| * <p>Another example is {@code Hashtable}, where {@code null} |
| * cannot be stored.</p> |
| */ |
| public static class Null implements Serializable { |
| /** |
| * Required for serialization support. Declare serialization compatibility with Commons Lang 1.0 |
| * |
| * @see java.io.Serializable |
| */ |
| private static final long serialVersionUID = 7092611880189329093L; |
| |
| /** |
| * Restricted constructor - singleton. |
| */ |
| Null() { |
| super(); |
| } |
| |
| /** |
| * <p>Ensure singleton.</p> |
| * |
| * @return the singleton value |
| */ |
| private Object readResolve() { |
| return ObjectUtils.NULL; |
| } |
| } |
| |
| } |
