ArrayTypeAdapter.java

/*
 * 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.smartandroid.sa.json.internal.bind;

import java.io.IOException;
import java.lang.reflect.Array;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;

import com.smartandroid.sa.json.internal.$Gson$Types;
import com.smartandroid.sa.json.reflect.TypeToken;
import com.smartandroid.sa.json.stream.JsonReader;
import com.smartandroid.sa.json.stream.JsonToken;
import com.smartandroid.sa.json.stream.JsonWriter;

/**
 * Adapt an array of objects.
 */
public final class ArrayTypeAdapter<E> extends TypeAdapter<Object> {
	public static final Factory FACTORY = new Factory() {
		public <T> TypeAdapter<T> create(MiniGson context,
				TypeToken<T> typeToken) {
			Type type = typeToken.getType();
			if (!(type instanceof GenericArrayType || type instanceof Class
					&& ((Class<?>) type).isArray())) {
				return null;
			}

			Type componentType = $Gson$Types.getArrayComponentType(type);
			TypeAdapter<?> componentTypeAdapter = context.getAdapter(TypeToken
					.get(componentType));
			@SuppressWarnings("unchecked")
			// create() doesn't define a type parameter
			TypeAdapter<T> result = new ArrayTypeAdapter(context,
					componentTypeAdapter, $Gson$Types.getRawType(componentType));
			return result;
		}
	};

	private final Class<E> componentType;
	private final TypeAdapter<E> componentTypeAdapter;

	public ArrayTypeAdapter(MiniGson context,
			TypeAdapter<E> componentTypeAdapter, Class<E> componentType) {
		this.componentTypeAdapter = new TypeAdapterRuntimeTypeWrapper<E>(
				context, componentTypeAdapter, componentType);
		this.componentType = componentType;
	}

	public Object read(JsonReader reader) throws IOException {
		if (reader.peek() == JsonToken.NULL) {
			reader.nextNull(); // TODO: does this belong here?
			return null;
		}

		List<E> list = new ArrayList<E>();
		reader.beginArray();
		while (reader.hasNext()) {
			E instance = componentTypeAdapter.read(reader);
			list.add(instance);
		}
		reader.endArray();
		Object array = Array.newInstance(componentType, list.size());
		for (int i = 0; i < list.size(); i++) {
			Array.set(array, i, list.get(i));
		}
		return array;
	}

	@Override
	public void write(JsonWriter writer, Object array) throws IOException {
		if (array == null) {
			writer.nullValue(); // TODO: better policy here?
			return;
		}

		writer.beginArray();
		for (int i = 0, length = Array.getLength(array); i < length; i++) {
			final E value = (E) Array.get(array, i);
			componentTypeAdapter.write(writer, value);
		}
		writer.endArray();
	}
}