535 lines
22 KiB
Java
535 lines
22 KiB
Java
/*
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* Copyright (C) 2011 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.bind;
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import com.google.gson.FieldNamingStrategy;
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import com.google.gson.Gson;
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import com.google.gson.JsonIOException;
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import com.google.gson.JsonParseException;
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import com.google.gson.JsonSyntaxException;
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import com.google.gson.ReflectionAccessFilter;
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import com.google.gson.ReflectionAccessFilter.FilterResult;
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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.JsonAdapter;
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import com.google.gson.annotations.SerializedName;
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import com.google.gson.internal.$Gson$Types;
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import com.google.gson.internal.ConstructorConstructor;
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import com.google.gson.internal.Excluder;
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import com.google.gson.internal.ObjectConstructor;
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import com.google.gson.internal.Primitives;
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import com.google.gson.internal.ReflectionAccessFilterHelper;
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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.JsonToken;
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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.AccessibleObject;
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import java.lang.reflect.Constructor;
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import java.lang.reflect.Field;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.Member;
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import java.lang.reflect.Method;
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import java.lang.reflect.Modifier;
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import java.lang.reflect.Type;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.HashMap;
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import java.util.LinkedHashMap;
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import java.util.List;
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import java.util.Map;
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/**
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* Type adapter that reflects over the fields and methods of a class.
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*/
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public final class ReflectiveTypeAdapterFactory implements TypeAdapterFactory {
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private final ConstructorConstructor constructorConstructor;
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private final FieldNamingStrategy fieldNamingPolicy;
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private final Excluder excluder;
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private final JsonAdapterAnnotationTypeAdapterFactory jsonAdapterFactory;
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private final List<ReflectionAccessFilter> reflectionFilters;
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public ReflectiveTypeAdapterFactory(ConstructorConstructor constructorConstructor,
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FieldNamingStrategy fieldNamingPolicy, Excluder excluder,
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JsonAdapterAnnotationTypeAdapterFactory jsonAdapterFactory,
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List<ReflectionAccessFilter> reflectionFilters) {
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this.constructorConstructor = constructorConstructor;
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this.fieldNamingPolicy = fieldNamingPolicy;
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this.excluder = excluder;
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this.jsonAdapterFactory = jsonAdapterFactory;
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this.reflectionFilters = reflectionFilters;
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}
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private boolean includeField(Field f, boolean serialize) {
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return !excluder.excludeClass(f.getType(), serialize) && !excluder.excludeField(f, serialize);
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}
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/** first element holds the default name */
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private List<String> getFieldNames(Field f) {
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SerializedName annotation = f.getAnnotation(SerializedName.class);
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if (annotation == null) {
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String name = fieldNamingPolicy.translateName(f);
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return Collections.singletonList(name);
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}
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String serializedName = annotation.value();
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String[] alternates = annotation.alternate();
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if (alternates.length == 0) {
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return Collections.singletonList(serializedName);
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}
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List<String> fieldNames = new ArrayList<>(alternates.length + 1);
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fieldNames.add(serializedName);
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Collections.addAll(fieldNames, alternates);
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return fieldNames;
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}
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@Override
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public <T> TypeAdapter<T> create(Gson gson, final TypeToken<T> type) {
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Class<? super T> raw = type.getRawType();
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if (!Object.class.isAssignableFrom(raw)) {
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return null; // it's a primitive!
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}
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FilterResult filterResult =
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ReflectionAccessFilterHelper.getFilterResult(reflectionFilters, raw);
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if (filterResult == FilterResult.BLOCK_ALL) {
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throw new JsonIOException(
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"ReflectionAccessFilter does not permit using reflection for " + raw
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+ ". Register a TypeAdapter for this type or adjust the access filter.");
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}
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boolean blockInaccessible = filterResult == FilterResult.BLOCK_INACCESSIBLE;
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// If the type is actually a Java Record, we need to use the RecordAdapter instead. This will always be false
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// on JVMs that do not support records.
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if (ReflectionHelper.isRecord(raw)) {
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@SuppressWarnings("unchecked")
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TypeAdapter<T> adapter = (TypeAdapter<T>) new RecordAdapter<>(raw,
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getBoundFields(gson, type, raw, blockInaccessible, true), blockInaccessible);
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return adapter;
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}
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ObjectConstructor<T> constructor = constructorConstructor.get(type);
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return new FieldReflectionAdapter<>(constructor, getBoundFields(gson, type, raw, blockInaccessible, false));
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}
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private static <M extends AccessibleObject & Member> void checkAccessible(Object object, M member) {
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if (!ReflectionAccessFilterHelper.canAccess(member, Modifier.isStatic(member.getModifiers()) ? null : object)) {
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String memberDescription = ReflectionHelper.getAccessibleObjectDescription(member, true);
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throw new JsonIOException(memberDescription + " is not accessible and ReflectionAccessFilter does not"
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+ " permit making it accessible. Register a TypeAdapter for the declaring type, adjust the"
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+ " access filter or increase the visibility of the element and its declaring type.");
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}
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}
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private BoundField createBoundField(
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final Gson context, final Field field, final Method accessor, final String name,
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final TypeToken<?> fieldType, boolean serialize, boolean deserialize,
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final boolean blockInaccessible) {
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final boolean isPrimitive = Primitives.isPrimitive(fieldType.getRawType());
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int modifiers = field.getModifiers();
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final boolean isStaticFinalField = Modifier.isStatic(modifiers) && Modifier.isFinal(modifiers);
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JsonAdapter annotation = field.getAnnotation(JsonAdapter.class);
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TypeAdapter<?> mapped = null;
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if (annotation != null) {
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// This is not safe; requires that user has specified correct adapter class for @JsonAdapter
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mapped = jsonAdapterFactory.getTypeAdapter(
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constructorConstructor, context, fieldType, annotation);
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}
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final boolean jsonAdapterPresent = mapped != null;
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if (mapped == null) mapped = context.getAdapter(fieldType);
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@SuppressWarnings("unchecked")
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final TypeAdapter<Object> typeAdapter = (TypeAdapter<Object>) mapped;
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return new BoundField(name, field, serialize, deserialize) {
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@Override void write(JsonWriter writer, Object source)
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throws IOException, IllegalAccessException {
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if (!serialized) return;
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if (blockInaccessible) {
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if (accessor == null) {
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checkAccessible(source, field);
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} else {
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// Note: This check might actually be redundant because access check for canonical
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// constructor should have failed already
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checkAccessible(source, accessor);
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}
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}
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Object fieldValue;
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if (accessor != null) {
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try {
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fieldValue = accessor.invoke(source);
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} catch (InvocationTargetException e) {
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String accessorDescription = ReflectionHelper.getAccessibleObjectDescription(accessor, false);
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throw new JsonIOException("Accessor " + accessorDescription + " threw exception", e.getCause());
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}
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} else {
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fieldValue = field.get(source);
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}
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if (fieldValue == source) {
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// avoid direct recursion
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return;
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}
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writer.name(name);
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TypeAdapter<Object> t = jsonAdapterPresent ? typeAdapter
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: new TypeAdapterRuntimeTypeWrapper<>(context, typeAdapter, fieldType.getType());
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t.write(writer, fieldValue);
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}
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@Override
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void readIntoArray(JsonReader reader, int index, Object[] target) throws IOException, JsonParseException {
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Object fieldValue = typeAdapter.read(reader);
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if (fieldValue == null && isPrimitive) {
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throw new JsonParseException("null is not allowed as value for record component '" + fieldName + "'"
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+ " of primitive type; at path " + reader.getPath());
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}
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target[index] = fieldValue;
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}
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@Override
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void readIntoField(JsonReader reader, Object target)
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throws IOException, IllegalAccessException {
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Object fieldValue = typeAdapter.read(reader);
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if (fieldValue != null || !isPrimitive) {
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if (blockInaccessible) {
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checkAccessible(target, field);
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} else if (isStaticFinalField) {
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// Reflection does not permit setting value of `static final` field, even after calling `setAccessible`
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// Handle this here to avoid causing IllegalAccessException when calling `Field.set`
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String fieldDescription = ReflectionHelper.getAccessibleObjectDescription(field, false);
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throw new JsonIOException("Cannot set value of 'static final' " + fieldDescription);
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}
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field.set(target, fieldValue);
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}
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}
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};
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}
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private Map<String, BoundField> getBoundFields(Gson context, TypeToken<?> type, Class<?> raw,
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boolean blockInaccessible, boolean isRecord) {
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Map<String, BoundField> result = new LinkedHashMap<>();
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if (raw.isInterface()) {
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return result;
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}
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Class<?> originalRaw = raw;
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while (raw != Object.class) {
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Field[] fields = raw.getDeclaredFields();
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// For inherited fields, check if access to their declaring class is allowed
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if (raw != originalRaw && fields.length > 0) {
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FilterResult filterResult = ReflectionAccessFilterHelper.getFilterResult(reflectionFilters, raw);
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if (filterResult == FilterResult.BLOCK_ALL) {
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throw new JsonIOException("ReflectionAccessFilter does not permit using reflection for " + raw
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+ " (supertype of " + originalRaw + "). Register a TypeAdapter for this type"
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+ " or adjust the access filter.");
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}
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blockInaccessible = filterResult == FilterResult.BLOCK_INACCESSIBLE;
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}
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for (Field field : fields) {
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boolean serialize = includeField(field, true);
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boolean deserialize = includeField(field, false);
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if (!serialize && !deserialize) {
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continue;
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}
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// The accessor method is only used for records. If the type is a record, we will read out values
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// via its accessor method instead of via reflection. This way we will bypass the accessible restrictions
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Method accessor = null;
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if (isRecord) {
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// If there is a static field on a record, there will not be an accessor. Instead we will use the default
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// field serialization logic, but for deserialization the field is excluded for simplicity. Note that Gson
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// ignores static fields by default, but GsonBuilder.excludeFieldsWithModifiers can overwrite this.
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if (Modifier.isStatic(field.getModifiers())) {
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deserialize = false;
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} else {
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accessor = ReflectionHelper.getAccessor(raw, field);
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// If blockInaccessible, skip and perform access check later
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if (!blockInaccessible) {
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ReflectionHelper.makeAccessible(accessor);
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}
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// @SerializedName can be placed on accessor method, but it is not supported there
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// If field and method have annotation it is not easily possible to determine if accessor method
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// is implicit and has inherited annotation, or if it is explicitly declared with custom annotation
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if (accessor.getAnnotation(SerializedName.class) != null
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&& field.getAnnotation(SerializedName.class) == null) {
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String methodDescription = ReflectionHelper.getAccessibleObjectDescription(accessor, false);
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throw new JsonIOException("@SerializedName on " + methodDescription + " is not supported");
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}
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}
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}
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// If blockInaccessible, skip and perform access check later
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// For Records if the accessor method is used the field does not have to be made accessible
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if (!blockInaccessible && accessor == null) {
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ReflectionHelper.makeAccessible(field);
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}
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Type fieldType = $Gson$Types.resolve(type.getType(), raw, field.getGenericType());
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List<String> fieldNames = getFieldNames(field);
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BoundField previous = null;
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for (int i = 0, size = fieldNames.size(); i < size; ++i) {
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String name = fieldNames.get(i);
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if (i != 0) serialize = false; // only serialize the default name
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BoundField boundField = createBoundField(context, field, accessor, name,
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TypeToken.get(fieldType), serialize, deserialize, blockInaccessible);
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BoundField replaced = result.put(name, boundField);
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if (previous == null) previous = replaced;
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}
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if (previous != null) {
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throw new IllegalArgumentException("Class " + originalRaw.getName()
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+ " declares multiple JSON fields named '" + previous.name + "'; conflict is caused"
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+ " by fields " + ReflectionHelper.fieldToString(previous.field) + " and " + ReflectionHelper.fieldToString(field));
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}
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}
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type = TypeToken.get($Gson$Types.resolve(type.getType(), raw, raw.getGenericSuperclass()));
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raw = type.getRawType();
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}
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return result;
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}
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static abstract class BoundField {
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final String name;
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final Field field;
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/** Name of the underlying field */
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final String fieldName;
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final boolean serialized;
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final boolean deserialized;
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protected BoundField(String name, Field field, boolean serialized, boolean deserialized) {
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this.name = name;
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this.field = field;
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this.fieldName = field.getName();
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this.serialized = serialized;
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this.deserialized = deserialized;
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}
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/** Read this field value from the source, and append its JSON value to the writer */
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abstract void write(JsonWriter writer, Object source) throws IOException, IllegalAccessException;
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/** Read the value into the target array, used to provide constructor arguments for records */
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abstract void readIntoArray(JsonReader reader, int index, Object[] target) throws IOException, JsonParseException;
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/** Read the value from the reader, and set it on the corresponding field on target via reflection */
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abstract void readIntoField(JsonReader reader, Object target) throws IOException, IllegalAccessException;
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}
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/**
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* Base class for Adapters produced by this factory.
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*
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* <p>The {@link RecordAdapter} is a special case to handle records for JVMs that support it, for
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* all other types we use the {@link FieldReflectionAdapter}. This class encapsulates the common
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* logic for serialization and deserialization. During deserialization, we construct an
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* accumulator A, which we use to accumulate values from the source JSON. After the object has been read in
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* full, the {@link #finalize(Object)} method is used to convert the accumulator to an instance
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* of T.
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*
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* @param <T> type of objects that this Adapter creates.
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* @param <A> type of accumulator used to build the deserialization result.
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*/
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// This class is public because external projects check for this class with `instanceof` (even though it is internal)
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public static abstract class Adapter<T, A> extends TypeAdapter<T> {
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final Map<String, BoundField> boundFields;
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Adapter(Map<String, BoundField> boundFields) {
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this.boundFields = boundFields;
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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 (value == null) {
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out.nullValue();
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return;
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}
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out.beginObject();
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try {
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for (BoundField boundField : boundFields.values()) {
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boundField.write(out, value);
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}
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} catch (IllegalAccessException e) {
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throw ReflectionHelper.createExceptionForUnexpectedIllegalAccess(e);
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}
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out.endObject();
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}
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@Override
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public T read(JsonReader in) throws IOException {
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if (in.peek() == JsonToken.NULL) {
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in.nextNull();
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return null;
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}
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A accumulator = createAccumulator();
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try {
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in.beginObject();
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while (in.hasNext()) {
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String name = in.nextName();
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BoundField field = boundFields.get(name);
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if (field == null || !field.deserialized) {
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in.skipValue();
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} else {
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readField(accumulator, in, field);
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}
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}
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} catch (IllegalStateException e) {
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throw new JsonSyntaxException(e);
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} catch (IllegalAccessException e) {
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throw ReflectionHelper.createExceptionForUnexpectedIllegalAccess(e);
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}
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in.endObject();
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return finalize(accumulator);
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}
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/** Create the Object that will be used to collect each field value */
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abstract A createAccumulator();
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/**
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* Read a single BoundField into the accumulator. The JsonReader will be pointed at the
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* start of the value for the BoundField to read from.
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*/
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abstract void readField(A accumulator, JsonReader in, BoundField field)
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throws IllegalAccessException, IOException;
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/** Convert the accumulator to a final instance of T. */
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abstract T finalize(A accumulator);
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}
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private static final class FieldReflectionAdapter<T> extends Adapter<T, T> {
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private final ObjectConstructor<T> constructor;
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FieldReflectionAdapter(ObjectConstructor<T> constructor, Map<String, BoundField> boundFields) {
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super(boundFields);
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this.constructor = constructor;
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}
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@Override
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T createAccumulator() {
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return constructor.construct();
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}
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@Override
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void readField(T accumulator, JsonReader in, BoundField field)
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throws IllegalAccessException, IOException {
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field.readIntoField(in, accumulator);
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}
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@Override
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T finalize(T accumulator) {
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return accumulator;
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}
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}
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private static final class RecordAdapter<T> extends Adapter<T, Object[]> {
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static final Map<Class<?>, Object> PRIMITIVE_DEFAULTS = primitiveDefaults();
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// The canonical constructor of the record
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private final Constructor<T> constructor;
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// Array of arguments to the constructor, initialized with default values for primitives
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private final Object[] constructorArgsDefaults;
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// Map from component names to index into the constructors arguments.
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private final Map<String, Integer> componentIndices = new HashMap<>();
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RecordAdapter(Class<T> raw, Map<String, BoundField> boundFields, boolean blockInaccessible) {
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super(boundFields);
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constructor = ReflectionHelper.getCanonicalRecordConstructor(raw);
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if (blockInaccessible) {
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checkAccessible(null, constructor);
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} else {
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// Ensure the constructor is accessible
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ReflectionHelper.makeAccessible(constructor);
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}
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String[] componentNames = ReflectionHelper.getRecordComponentNames(raw);
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for (int i = 0; i < componentNames.length; i++) {
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componentIndices.put(componentNames[i], i);
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}
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Class<?>[] parameterTypes = constructor.getParameterTypes();
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// We need to ensure that we are passing non-null values to primitive fields in the constructor. To do this,
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// we create an Object[] where all primitives are initialized to non-null values.
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constructorArgsDefaults = new Object[parameterTypes.length];
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for (int i = 0; i < parameterTypes.length; i++) {
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// This will correctly be null for non-primitive types:
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constructorArgsDefaults[i] = PRIMITIVE_DEFAULTS.get(parameterTypes[i]);
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}
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}
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private static Map<Class<?>, Object> primitiveDefaults() {
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Map<Class<?>, Object> zeroes = new HashMap<>();
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zeroes.put(byte.class, (byte) 0);
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zeroes.put(short.class, (short) 0);
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zeroes.put(int.class, 0);
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zeroes.put(long.class, 0L);
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zeroes.put(float.class, 0F);
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zeroes.put(double.class, 0D);
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|
zeroes.put(char.class, '\0');
|
|
zeroes.put(boolean.class, false);
|
|
return zeroes;
|
|
}
|
|
|
|
@Override
|
|
Object[] createAccumulator() {
|
|
return constructorArgsDefaults.clone();
|
|
}
|
|
|
|
@Override
|
|
void readField(Object[] accumulator, JsonReader in, BoundField field) throws IOException {
|
|
// Obtain the component index from the name of the field backing it
|
|
Integer componentIndex = componentIndices.get(field.fieldName);
|
|
if (componentIndex == null) {
|
|
throw new IllegalStateException(
|
|
"Could not find the index in the constructor '" + ReflectionHelper.constructorToString(constructor) + "'"
|
|
+ " for field with name '" + field.fieldName + "',"
|
|
+ " unable to determine which argument in the constructor the field corresponds"
|
|
+ " to. This is unexpected behavior, as we expect the RecordComponents to have the"
|
|
+ " same names as the fields in the Java class, and that the order of the"
|
|
+ " RecordComponents is the same as the order of the canonical constructor parameters.");
|
|
}
|
|
field.readIntoArray(in, componentIndex, accumulator);
|
|
}
|
|
|
|
@Override
|
|
T finalize(Object[] accumulator) {
|
|
try {
|
|
return constructor.newInstance(accumulator);
|
|
} catch (IllegalAccessException e) {
|
|
throw ReflectionHelper.createExceptionForUnexpectedIllegalAccess(e);
|
|
}
|
|
// Note: InstantiationException should be impossible because record class is not abstract;
|
|
// IllegalArgumentException should not be possible unless a bad adapter returns objects of the wrong type
|
|
catch (InstantiationException | IllegalArgumentException e) {
|
|
throw new RuntimeException(
|
|
"Failed to invoke constructor '" + ReflectionHelper.constructorToString(constructor) + "'"
|
|
+ " with args " + Arrays.toString(accumulator), e);
|
|
}
|
|
catch (InvocationTargetException e) {
|
|
// TODO: JsonParseException ?
|
|
throw new RuntimeException(
|
|
"Failed to invoke constructor '" + ReflectionHelper.constructorToString(constructor) + "'"
|
|
+ " with args " + Arrays.toString(accumulator), e.getCause());
|
|
}
|
|
}
|
|
}
|
|
}
|