code: /*
   * 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 tools.com.google.gson.internal.bind;
  
  import tools.com.google.gson.Gson;
  import tools.com.google.gson.TypeAdapter;
  import tools.com.google.gson.TypeAdapterFactory;
  import tools.com.google.gson.internal.LinkedTreeMap;
  import tools.com.google.gson.reflect.TypeToken;
  import tools.com.google.gson.stream.JsonReader;
  import tools.com.google.gson.stream.JsonToken;
  import tools.com.google.gson.stream.JsonWriter;
  
  import java.io.IOException;
  import java.util.ArrayList;
  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> {
    public static final TypeAdapterFactory FACTORY = 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);
        }
        return null;
      }
    };
  
    private final Gson gson;
  
    ObjectTypeAdapter(Gson gson) {
      this.gson = gson;
    }
  
    @Override public Object read(JsonReader in) throws IOException {
      JsonToken token = in.peek();
      switch (token) {
      case BEGIN_ARRAY:
        List<Object> list = new ArrayList<Object>();
        in.beginArray();
        while (in.hasNext()) {
          list.add(read(in));
        }
        in.endArray();
        return list;
  
      case BEGIN_OBJECT:
        Map<String, Object> map = new LinkedTreeMap<String, Object>();
        in.beginObject();
        while (in.hasNext()) {
          map.put(in.nextName(), read(in));
        }
        in.endObject();
        return map;
  
      case STRING:
        return in.nextString();
  
      case NUMBER:
        return in.nextDouble();
  
      case BOOLEAN:
        return in.nextBoolean();
  
      case NULL:
        in.nextNull();
        return null;
  
      default:
        throw new IllegalStateException();
      }
    }
  
    @SuppressWarnings("unchecked")
    @Override public void write(JsonWriter out, Object value) throws IOException {
      if (value == null) {
        out.nullValue();
        return;
      }
  
      TypeAdapter<Object> typeAdapter = (TypeAdapter<Object>) gson.getAdapter(value.getClass());
      if (typeAdapter instanceof ObjectTypeAdapter) {
        out.beginObject();
        out.endObject();
        return;
      }
  
      typeAdapter.write(out, value);
    }
  }
  