JsonSerializationContext.java

/*
 * Copyright (C) 2008 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;

import java.lang.reflect.Type;

/**
 * Context for serialization that is passed to a custom serializer during
 * invocation of its
 * {@link JsonSerializer#serialize(Object, Type, JsonSerializationContext)}
 * method.
 * 
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
public class JsonSerializationContext {

	private final ObjectNavigator objectNavigator;
	private final FieldNamingStrategy2 fieldNamingPolicy;
	private final ParameterizedTypeHandlerMap<JsonSerializer<?>> serializers;
	private final boolean serializeNulls;
	private final MemoryRefStack ancestors;

	JsonSerializationContext(ObjectNavigator objectNavigator,
			FieldNamingStrategy2 fieldNamingPolicy, boolean serializeNulls,
			ParameterizedTypeHandlerMap<JsonSerializer<?>> serializers) {
		this.objectNavigator = objectNavigator;
		this.fieldNamingPolicy = fieldNamingPolicy;
		this.serializeNulls = serializeNulls;
		this.serializers = serializers;
		this.ancestors = new MemoryRefStack();
	}

	JsonSerializationContext() {
		this(null, null, false, null);
	}

	/**
	 * Invokes default serialization on the specified object.
	 * 
	 * @param src
	 *            the object that needs to be serialized.
	 * @return a tree of {@link JsonElement}s corresponding to the serialized
	 *         form of {@code src}.
	 */
	public JsonElement serialize(Object src) {
		if (src == null) {
			return JsonNull.INSTANCE;
		}
		return serialize(src, src.getClass(), false, false);
	}

	/**
	 * Invokes default serialization on the specified object passing the
	 * specific type information. It should never be invoked on the element
	 * received as a parameter of the
	 * {@link JsonSerializer#serialize(Object, Type, JsonSerializationContext)}
	 * method. Doing so will result in an infinite loop since Gson will in-turn
	 * call the custom serializer again.
	 * 
	 * @param src
	 *            the object that needs to be serialized.
	 * @param typeOfSrc
	 *            the actual genericized type of src object.
	 * @return a tree of {@link JsonElement}s corresponding to the serialized
	 *         form of {@code src}.
	 */
	public JsonElement serialize(Object src, Type typeOfSrc) {
		return serialize(src, typeOfSrc, true, false);
	}

	public JsonElement serializeDefault(Object src, Type typeOfSrc) {
		return serialize(src, typeOfSrc, true, true);
	}

	JsonElement serialize(Object src, Type typeOfSrc, boolean preserveType,
			boolean defaultOnly) {
		if (src == null) {
			return JsonNull.INSTANCE;
		}
		JsonSerializationVisitor visitor = new JsonSerializationVisitor(
				objectNavigator, fieldNamingPolicy, serializeNulls,
				serializers, this, ancestors);
		ObjectTypePair objTypePair = new ObjectTypePair(src, typeOfSrc,
				preserveType, defaultOnly);
		objectNavigator.accept(objTypePair, visitor);
		return visitor.getJsonElement();
	}
}