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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;
import com.google.gson.internal.$Gson$Preconditions;
import com.google.gson.internal.Streams;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;
import java.io.IOException;
/**
* Adapts a Gson 1.x tree-style adapter as a streaming TypeAdapter. Since the
* tree adapter may be serialization-only or deserialization-only, this class
* has a facility to lookup a delegate type adapter on demand.
*/
final class TreeTypeAdapter<T> extends TypeAdapter<T> {
private final JsonSerializer<T> serializer;
private final JsonDeserializer<T> deserializer;
private final Gson gson;
private final TypeToken<T> typeToken;
private final TypeAdapterFactory skipPast;
/** The delegate is lazily created because it may not be needed, and creating it may fail. */
private TypeAdapter<T> delegate;
private TreeTypeAdapter(JsonSerializer<T> serializer, JsonDeserializer<T> deserializer,
Gson gson, TypeToken<T> typeToken, TypeAdapterFactory skipPast) {
this.serializer = serializer;
this.deserializer = deserializer;
this.gson = gson;
this.typeToken = typeToken;
this.skipPast = skipPast;
}
@Override public T read(JsonReader in) throws IOException {
if (deserializer == null) {
return delegate().read(in);
}
JsonElement value = Streams.parse(in);
if (value.isJsonNull()) {
return null;
}
return deserializer.deserialize(value, typeToken.getType(), gson.deserializationContext);
}
@Override public void write(JsonWriter out, T value) throws IOException {
if (serializer == null) {
delegate().write(out, value);
return;
}
if (value == null) {
out.nullValue();
return;
}
JsonElement tree = serializer.serialize(value, typeToken.getType(), gson.serializationContext);
Streams.write(tree, out);
}
private TypeAdapter<T> delegate() {
TypeAdapter<T> d = delegate;
return d != null
? d
: (delegate = gson.getDelegateAdapter(skipPast, typeToken));
}
/**
* Returns a new factory that will match each type against {@code exactType}.
*/
public static TypeAdapterFactory newFactory(TypeToken<?> exactType, Object typeAdapter) {
return new SingleTypeFactory(typeAdapter, exactType, false, null);
}
/**
* Returns a new factory that will match each type and its raw type against
* {@code exactType}.
*/
public static TypeAdapterFactory newFactoryWithMatchRawType(
TypeToken<?> exactType, Object typeAdapter) {
// only bother matching raw types if exact type is a raw type
boolean matchRawType = exactType.getType() == exactType.getRawType();
return new SingleTypeFactory(typeAdapter, exactType, matchRawType, null);
}
/**
* Returns a new factory that will match each type's raw type for assignability
* to {@code hierarchyType}.
*/
public static TypeAdapterFactory newTypeHierarchyFactory(
Class<?> hierarchyType, Object typeAdapter) {
return new SingleTypeFactory(typeAdapter, null, false, hierarchyType);
}
private static class SingleTypeFactory implements TypeAdapterFactory {
private final TypeToken<?> exactType;
private final boolean matchRawType;
private final Class<?> hierarchyType;
private final JsonSerializer<?> serializer;
private final JsonDeserializer<?> deserializer;
private SingleTypeFactory(Object typeAdapter, TypeToken<?> exactType, boolean matchRawType,
Class<?> hierarchyType) {
serializer = typeAdapter instanceof JsonSerializer
? (JsonSerializer<?>) typeAdapter
: null;
deserializer = typeAdapter instanceof JsonDeserializer
? (JsonDeserializer<?>) typeAdapter
: null;
$Gson$Preconditions.checkArgument(serializer != null || deserializer != null);
this.exactType = exactType;
this.matchRawType = matchRawType;
this.hierarchyType = hierarchyType;
}
@SuppressWarnings("unchecked") // guarded by typeToken.equals() call
public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
boolean matches = exactType != null
? exactType.equals(type) || matchRawType && exactType.getType() == type.getRawType()
: hierarchyType.isAssignableFrom(type.getRawType());
return matches
? new TreeTypeAdapter<T>((JsonSerializer<T>) serializer,
(JsonDeserializer<T>) deserializer, gson, type, this)
: null;
}
}
}
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