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/*
* Copyright (C) 2011 Google Inc.
*
* Licensed 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.gson.internal.bind;
import com.google.gson.Gson;
import com.google.gson.ToNumberPolicy;
import com.google.gson.ToNumberStrategy;
import com.google.gson.TypeAdapter;
import com.google.gson.TypeAdapterFactory;
import com.google.gson.internal.LinkedTreeMap;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;
import com.google.gson.stream.JsonWriter;
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.List;
import java.util.Map;
/**
* Adapts types whose static type is only 'Object'. Uses getClass() on
* serialization and a primitive/Map/List on deserialization.
*/
public final class ObjectTypeAdapter extends TypeAdapter<Object> {
/**
* Gson default factory using {@link ToNumberPolicy#DOUBLE}.
*/
private static final TypeAdapterFactory DOUBLE_FACTORY = newFactory(ToNumberPolicy.DOUBLE);
private final Gson gson;
private final ToNumberStrategy toNumberStrategy;
private ObjectTypeAdapter(Gson gson, ToNumberStrategy toNumberStrategy) {
this.gson = gson;
this.toNumberStrategy = toNumberStrategy;
}
private static TypeAdapterFactory newFactory(final ToNumberStrategy toNumberStrategy) {
return new TypeAdapterFactory() {
@SuppressWarnings("unchecked")
@Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
if (type.getRawType() == Object.class) {
return (TypeAdapter<T>) new ObjectTypeAdapter(gson, toNumberStrategy);
}
return null;
}
};
}
public static TypeAdapterFactory getFactory(ToNumberStrategy toNumberStrategy) {
if (toNumberStrategy == ToNumberPolicy.DOUBLE) {
return DOUBLE_FACTORY;
} else {
return newFactory(toNumberStrategy);
}
}
/**
* Tries to begin reading a JSON array or JSON object, returning {@code null} if
* the next element is neither of those.
*/
private Object tryBeginNesting(JsonReader in, JsonToken peeked) throws IOException {
switch (peeked) {
case BEGIN_ARRAY:
in.beginArray();
return new ArrayList<>();
case BEGIN_OBJECT:
in.beginObject();
return new LinkedTreeMap<>();
default:
return null;
}
}
/** Reads an {@code Object} which cannot have any nested elements */
private Object readTerminal(JsonReader in, JsonToken peeked) throws IOException {
switch (peeked) {
case STRING:
return in.nextString();
case NUMBER:
return toNumberStrategy.readNumber(in);
case BOOLEAN:
return in.nextBoolean();
case NULL:
in.nextNull();
return null;
default:
// When read(JsonReader) is called with JsonReader in invalid state
throw new IllegalStateException("Unexpected token: " + peeked);
}
}
@Override public Object read(JsonReader in) throws IOException {
// Either List or Map
Object current;
JsonToken peeked = in.peek();
current = tryBeginNesting(in, peeked);
if (current == null) {
return readTerminal(in, peeked);
}
Deque<Object> stack = new ArrayDeque<>();
while (true) {
while (in.hasNext()) {
String name = null;
// Name is only used for JSON object members
if (current instanceof Map) {
name = in.nextName();
}
peeked = in.peek();
Object value = tryBeginNesting(in, peeked);
boolean isNesting = value != null;
if (value == null) {
value = readTerminal(in, peeked);
}
if (current instanceof List) {
@SuppressWarnings("unchecked")
List<Object> list = (List<Object>) current;
list.add(value);
} else {
@SuppressWarnings("unchecked")
Map<String, Object> map = (Map<String, Object>) current;
map.put(name, value);
}
if (isNesting) {
stack.addLast(current);
current = value;
}
}
// End current element
if (current instanceof List) {
in.endArray();
} else {
in.endObject();
}
if (stack.isEmpty()) {
return current;
} else {
// Continue with enclosing element
current = stack.removeLast();
}
}
}
@Override public void write(JsonWriter out, Object value) throws IOException {
if (value == null) {
out.nullValue();
return;
}
@SuppressWarnings("unchecked")
TypeAdapter<Object> typeAdapter = (TypeAdapter<Object>) gson.getAdapter(value.getClass());
if (typeAdapter instanceof ObjectTypeAdapter) {
out.beginObject();
out.endObject();
return;
}
typeAdapter.write(out, value);
}
}
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