255 lines
8.2 KiB
Java
255 lines
8.2 KiB
Java
/*
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* Copyright (C) 2008 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.gson.internal;
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import com.google.gson.ExclusionStrategy;
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import com.google.gson.FieldAttributes;
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import com.google.gson.Gson;
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import com.google.gson.TypeAdapter;
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import com.google.gson.TypeAdapterFactory;
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import com.google.gson.annotations.Expose;
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import com.google.gson.annotations.Since;
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import com.google.gson.annotations.Until;
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import com.google.gson.internal.reflect.ReflectionHelper;
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import com.google.gson.reflect.TypeToken;
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import com.google.gson.stream.JsonReader;
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import com.google.gson.stream.JsonWriter;
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import java.io.IOException;
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import java.lang.reflect.Field;
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import java.lang.reflect.Modifier;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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/**
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* This class selects which fields and types to omit. It is configurable, supporting version
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* attributes {@link Since} and {@link Until}, modifiers, synthetic fields, anonymous and local
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* classes, inner classes, and fields with the {@link Expose} annotation.
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*
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* <p>This class is a type adapter factory; types that are excluded will be adapted to null. It may
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* delegate to another type adapter if only one direction is excluded.
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*
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* @author Joel Leitch
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* @author Jesse Wilson
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*/
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public final class Excluder implements TypeAdapterFactory, Cloneable {
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private static final double IGNORE_VERSIONS = -1.0d;
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public static final Excluder DEFAULT = new Excluder();
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private double version = IGNORE_VERSIONS;
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private int modifiers = Modifier.TRANSIENT | Modifier.STATIC;
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private boolean serializeInnerClasses = true;
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private boolean requireExpose;
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private List<ExclusionStrategy> serializationStrategies = Collections.emptyList();
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private List<ExclusionStrategy> deserializationStrategies = Collections.emptyList();
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@Override
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protected Excluder clone() {
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try {
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return (Excluder) super.clone();
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} catch (CloneNotSupportedException e) {
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throw new AssertionError(e);
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}
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}
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public Excluder withVersion(double ignoreVersionsAfter) {
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Excluder result = clone();
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result.version = ignoreVersionsAfter;
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return result;
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}
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public Excluder withModifiers(int... modifiers) {
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Excluder result = clone();
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result.modifiers = 0;
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for (int modifier : modifiers) {
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result.modifiers |= modifier;
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}
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return result;
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}
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public Excluder disableInnerClassSerialization() {
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Excluder result = clone();
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result.serializeInnerClasses = false;
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return result;
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}
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public Excluder excludeFieldsWithoutExposeAnnotation() {
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Excluder result = clone();
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result.requireExpose = true;
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return result;
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}
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public Excluder withExclusionStrategy(
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ExclusionStrategy exclusionStrategy, boolean serialization, boolean deserialization) {
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Excluder result = clone();
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if (serialization) {
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result.serializationStrategies = new ArrayList<>(serializationStrategies);
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result.serializationStrategies.add(exclusionStrategy);
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}
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if (deserialization) {
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result.deserializationStrategies = new ArrayList<>(deserializationStrategies);
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result.deserializationStrategies.add(exclusionStrategy);
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}
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return result;
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}
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@Override
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public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> type) {
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Class<?> rawType = type.getRawType();
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final boolean skipSerialize = excludeClass(rawType, true);
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final boolean skipDeserialize = excludeClass(rawType, false);
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if (!skipSerialize && !skipDeserialize) {
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return null;
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}
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return new TypeAdapter<T>() {
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/**
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* The delegate is lazily created because it may not be needed, and creating it may fail.
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* Field has to be {@code volatile} because {@link Gson} guarantees to be thread-safe.
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*/
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private volatile TypeAdapter<T> delegate;
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@Override
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public T read(JsonReader in) throws IOException {
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if (skipDeserialize) {
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in.skipValue();
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return null;
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}
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return delegate().read(in);
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}
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@Override
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public void write(JsonWriter out, T value) throws IOException {
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if (skipSerialize) {
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out.nullValue();
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return;
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}
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delegate().write(out, value);
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}
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private TypeAdapter<T> delegate() {
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// A race might lead to `delegate` being assigned by multiple threads but the last
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// assignment will stick
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TypeAdapter<T> d = delegate;
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return d != null ? d : (delegate = gson.getDelegateAdapter(Excluder.this, type));
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}
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};
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}
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public boolean excludeField(Field field, boolean serialize) {
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if ((modifiers & field.getModifiers()) != 0) {
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return true;
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}
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if (version != Excluder.IGNORE_VERSIONS
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&& !isValidVersion(field.getAnnotation(Since.class), field.getAnnotation(Until.class))) {
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return true;
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}
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if (field.isSynthetic()) {
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return true;
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}
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if (requireExpose) {
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Expose annotation = field.getAnnotation(Expose.class);
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if (annotation == null || (serialize ? !annotation.serialize() : !annotation.deserialize())) {
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return true;
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}
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}
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if (excludeClass(field.getType(), serialize)) {
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return true;
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}
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List<ExclusionStrategy> list = serialize ? serializationStrategies : deserializationStrategies;
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if (!list.isEmpty()) {
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FieldAttributes fieldAttributes = new FieldAttributes(field);
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for (ExclusionStrategy exclusionStrategy : list) {
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if (exclusionStrategy.shouldSkipField(fieldAttributes)) {
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return true;
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}
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}
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}
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return false;
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}
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// public for unit tests; can otherwise be private
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public boolean excludeClass(Class<?> clazz, boolean serialize) {
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if (version != Excluder.IGNORE_VERSIONS
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&& !isValidVersion(clazz.getAnnotation(Since.class), clazz.getAnnotation(Until.class))) {
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return true;
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}
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if (!serializeInnerClasses && isInnerClass(clazz)) {
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return true;
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}
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/*
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* Exclude anonymous and local classes because they can have synthetic fields capturing enclosing
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* values which makes serialization and deserialization unreliable.
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* Don't exclude anonymous enum subclasses because enum types have a built-in adapter.
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*
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* Exclude only for deserialization; for serialization allow because custom adapter might be
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* used; if no custom adapter exists reflection-based adapter otherwise excludes value.
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*
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* Cannot allow deserialization reliably here because some custom adapters like Collection adapter
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* fall back to creating instances using Unsafe, which would likely lead to runtime exceptions
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* for anonymous and local classes if they capture values.
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*/
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if (!serialize
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&& !Enum.class.isAssignableFrom(clazz)
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&& ReflectionHelper.isAnonymousOrNonStaticLocal(clazz)) {
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return true;
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}
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List<ExclusionStrategy> list = serialize ? serializationStrategies : deserializationStrategies;
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for (ExclusionStrategy exclusionStrategy : list) {
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if (exclusionStrategy.shouldSkipClass(clazz)) {
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return true;
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}
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}
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return false;
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}
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private static boolean isInnerClass(Class<?> clazz) {
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return clazz.isMemberClass() && !ReflectionHelper.isStatic(clazz);
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}
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private boolean isValidVersion(Since since, Until until) {
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return isValidSince(since) && isValidUntil(until);
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}
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private boolean isValidSince(Since annotation) {
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if (annotation != null) {
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double annotationVersion = annotation.value();
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return version >= annotationVersion;
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}
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return true;
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}
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private boolean isValidUntil(Until annotation) {
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if (annotation != null) {
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double annotationVersion = annotation.value();
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return version < annotationVersion;
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}
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return true;
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}
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}
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