/*
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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 cn.emay.sdk.util.json.gson.internal.bind;
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import java.io.IOException;
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import java.lang.reflect.Type;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Map;
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import cn.emay.sdk.util.json.gson.Gson;
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import cn.emay.sdk.util.json.gson.JsonElement;
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import cn.emay.sdk.util.json.gson.JsonPrimitive;
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import cn.emay.sdk.util.json.gson.JsonSyntaxException;
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import cn.emay.sdk.util.json.gson.TypeAdapter;
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import cn.emay.sdk.util.json.gson.TypeAdapterFactory;
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import cn.emay.sdk.util.json.gson.internal.$Gson$Types;
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import cn.emay.sdk.util.json.gson.internal.ConstructorConstructor;
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import cn.emay.sdk.util.json.gson.internal.JsonReaderInternalAccess;
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import cn.emay.sdk.util.json.gson.internal.ObjectConstructor;
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import cn.emay.sdk.util.json.gson.internal.Streams;
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import cn.emay.sdk.util.json.gson.reflect.TypeToken;
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import cn.emay.sdk.util.json.gson.stream.JsonReader;
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import cn.emay.sdk.util.json.gson.stream.JsonToken;
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import cn.emay.sdk.util.json.gson.stream.JsonWriter;
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/**
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* Adapts maps to either JSON objects or JSON arrays.
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*
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* <h3>Maps as JSON objects</h3> For primitive keys or when complex map key
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* serialization is not enabled, this converts Java {@link Map Maps} to JSON
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* Objects. This requires that map keys can be serialized as strings; this is
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* insufficient for some key types. For example, consider a map whose keys are
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* points on a grid. The default JSON form encodes reasonably:
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*
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* <pre>
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* {
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* @code
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* Map<Point, String> original = new LinkedHashMap<Point, String>();
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* original.put(new Point(5, 6), "a");
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* original.put(new Point(8, 8), "b");
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* System.out.println(gson.toJson(original, type));
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* }
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* </pre>
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*
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* The above code prints this JSON object:
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*
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* <pre>
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* {@code
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* {
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* "(5,6)": "a",
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* "(8,8)": "b"
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* }
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* }
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* </pre>
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*
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* But GSON is unable to deserialize this value because the JSON string name is
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* just the {@link Object#toString() toString()} of the map key. Attempting to
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* convert the above JSON to an object fails with a parse exception:
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*
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* <pre>
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* com.google.gson.JsonParseException: Expecting object found: "(5,6)"
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* at com.google.gson.JsonObjectDeserializationVisitor.visitFieldUsingCustomHandler
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* at com.google.gson.ObjectNavigator.navigateClassFields
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* ...
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* </pre>
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*
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* <h3>Maps as JSON arrays</h3> An alternative approach taken by this type
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* adapter when it is required and complex map key serialization is enabled is
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* to encode maps as arrays of map entries. Each map entry is a two element
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* array containing a key and a value. This approach is more flexible because
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* any type can be used as the map's key; not just strings. But it's also less
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* portable because the receiver of such JSON must be aware of the map entry
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* convention.
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*
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* <p>
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* Register this adapter when you are creating your GSON instance.
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*
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* <pre>
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* {
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* @code
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* Gson gson = new GsonBuilder().registerTypeAdapter(Map.class, new MapAsArrayTypeAdapter()).create();
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* }
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* </pre>
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*
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* This will change the structure of the JSON emitted by the code above. Now we
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* get an array. In this case the arrays elements are map entries:
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*
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* <pre>
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* {@code
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* [
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* [
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* {
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* "x": 5,
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* "y": 6
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* },
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* "a",
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* ],
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* [
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* {
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* "x": 8,
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* "y": 8
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* },
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* "b"
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* ]
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* ]
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* }
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* </pre>
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*
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* This format will serialize and deserialize just fine as long as this adapter
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* is registered.
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*/
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public final class MapTypeAdapterFactory implements TypeAdapterFactory {
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private final ConstructorConstructor constructorConstructor;
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final boolean complexMapKeySerialization;
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public MapTypeAdapterFactory(ConstructorConstructor constructorConstructor, boolean complexMapKeySerialization) {
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this.constructorConstructor = constructorConstructor;
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this.complexMapKeySerialization = complexMapKeySerialization;
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}
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@Override
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public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
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Type type = typeToken.getType();
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Class<? super T> rawType = typeToken.getRawType();
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if (!Map.class.isAssignableFrom(rawType)) {
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return null;
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}
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Class<?> rawTypeOfSrc = $Gson$Types.getRawType(type);
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Type[] keyAndValueTypes = $Gson$Types.getMapKeyAndValueTypes(type, rawTypeOfSrc);
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TypeAdapter<?> keyAdapter = getKeyAdapter(gson, keyAndValueTypes[0]);
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TypeAdapter<?> valueAdapter = gson.getAdapter(TypeToken.get(keyAndValueTypes[1]));
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ObjectConstructor<T> constructor = constructorConstructor.get(typeToken);
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@SuppressWarnings({ "unchecked", "rawtypes" })
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// we don't define a type parameter for the key or value types
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TypeAdapter<T> result = new Adapter(gson, keyAndValueTypes[0], keyAdapter, keyAndValueTypes[1], valueAdapter, constructor);
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return result;
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}
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/**
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* Returns a type adapter that writes the value as a string.
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*/
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private TypeAdapter<?> getKeyAdapter(Gson context, Type keyType) {
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return (keyType == boolean.class || keyType == Boolean.class) ? TypeAdapters.BOOLEAN_AS_STRING : context.getAdapter(TypeToken.get(keyType));
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}
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private final class Adapter<K, V> extends TypeAdapter<Map<K, V>> {
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private final TypeAdapter<K> keyTypeAdapter;
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private final TypeAdapter<V> valueTypeAdapter;
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private final ObjectConstructor<? extends Map<K, V>> constructor;
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public Adapter(Gson context, Type keyType, TypeAdapter<K> keyTypeAdapter, Type valueType, TypeAdapter<V> valueTypeAdapter, ObjectConstructor<? extends Map<K, V>> constructor) {
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this.keyTypeAdapter = new TypeAdapterRuntimeTypeWrapper<K>(context, keyTypeAdapter, keyType);
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this.valueTypeAdapter = new TypeAdapterRuntimeTypeWrapper<V>(context, valueTypeAdapter, valueType);
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this.constructor = constructor;
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}
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@Override
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public Map<K, V> read(JsonReader in) throws IOException {
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JsonToken peek = in.peek();
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if (peek == JsonToken.NULL) {
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in.nextNull();
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return null;
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}
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Map<K, V> map = constructor.construct();
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if (peek == JsonToken.BEGIN_ARRAY) {
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in.beginArray();
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while (in.hasNext()) {
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in.beginArray(); // entry array
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K key = keyTypeAdapter.read(in);
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V value = valueTypeAdapter.read(in);
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V replaced = map.put(key, value);
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if (replaced != null) {
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throw new JsonSyntaxException("duplicate key: " + key);
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}
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in.endArray();
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}
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in.endArray();
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} else {
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in.beginObject();
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while (in.hasNext()) {
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JsonReaderInternalAccess.INSTANCE.promoteNameToValue(in);
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K key = keyTypeAdapter.read(in);
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V value = valueTypeAdapter.read(in);
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V replaced = map.put(key, value);
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if (replaced != null) {
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throw new JsonSyntaxException("duplicate key: " + key);
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}
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}
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in.endObject();
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}
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return map;
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}
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@Override
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public void write(JsonWriter out, Map<K, V> map) throws IOException {
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if (map == null) {
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out.nullValue();
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return;
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}
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if (!complexMapKeySerialization) {
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out.beginObject();
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for (Map.Entry<K, V> entry : map.entrySet()) {
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out.name(String.valueOf(entry.getKey()));
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valueTypeAdapter.write(out, entry.getValue());
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}
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out.endObject();
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return;
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}
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boolean hasComplexKeys = false;
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List<JsonElement> keys = new ArrayList<JsonElement>(map.size());
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List<V> values = new ArrayList<V>(map.size());
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for (Map.Entry<K, V> entry : map.entrySet()) {
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JsonElement keyElement = keyTypeAdapter.toJsonTree(entry.getKey());
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keys.add(keyElement);
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values.add(entry.getValue());
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hasComplexKeys |= keyElement.isJsonArray() || keyElement.isJsonObject();
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}
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if (hasComplexKeys) {
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out.beginArray();
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for (int i = 0; i < keys.size(); i++) {
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out.beginArray(); // entry array
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Streams.write(keys.get(i), out);
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valueTypeAdapter.write(out, values.get(i));
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out.endArray();
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}
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out.endArray();
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} else {
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out.beginObject();
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for (int i = 0; i < keys.size(); i++) {
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JsonElement keyElement = keys.get(i);
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out.name(keyToString(keyElement));
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valueTypeAdapter.write(out, values.get(i));
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}
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out.endObject();
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}
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}
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private String keyToString(JsonElement keyElement) {
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if (keyElement.isJsonPrimitive()) {
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JsonPrimitive primitive = keyElement.getAsJsonPrimitive();
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if (primitive.isNumber()) {
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return String.valueOf(primitive.getAsNumber());
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} else if (primitive.isBoolean()) {
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return Boolean.toString(primitive.getAsBoolean());
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} else if (primitive.isString()) {
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return primitive.getAsString();
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} else {
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throw new AssertionError();
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}
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} else if (keyElement.isJsonNull()) {
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return "null";
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} else {
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throw new AssertionError();
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}
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}
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}
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}
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