JsonArrayDeserializationVisitor.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.Array;
import java.lang.reflect.Type;

import com.smartandroid.sa.json.internal.$Gson$Types;

/**
 * A visitor that populates fields of an object with data from its equivalent
 * JSON representation
 * 
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
final class JsonArrayDeserializationVisitor<T> extends
		JsonDeserializationVisitor<T> {

	JsonArrayDeserializationVisitor(JsonArray jsonArray, Type arrayType,
			ObjectNavigator objectNavigator,
			FieldNamingStrategy2 fieldNamingPolicy,
			ObjectConstructor objectConstructor,
			ParameterizedTypeHandlerMap<JsonDeserializer<?>> deserializers,
			JsonDeserializationContext context) {
		super(jsonArray, arrayType, objectNavigator, fieldNamingPolicy,
				objectConstructor, deserializers, context);
	}

	@Override
	@SuppressWarnings("unchecked")
	protected T constructTarget() {
		if (!json.isJsonArray()) {
			throw new JsonParseException("Expecting array found: " + json);
		}
		JsonArray jsonArray = json.getAsJsonArray();
		if ($Gson$Types.isArray(targetType)) {
			// We know that we are getting back an array of the required type,
			// so
			// this typecasting is safe.
			return (T) objectConstructor.constructArray(
					$Gson$Types.getArrayComponentType(targetType),
					jsonArray.size());
		}
		// is a collection
		return (T) objectConstructor.construct($Gson$Types
				.getRawType(targetType));
	}

	public void visitArray(Object array, Type arrayType) {
		if (!json.isJsonArray()) {
			throw new JsonParseException("Expecting array found: " + json);
		}
		JsonArray jsonArray = json.getAsJsonArray();
		for (int i = 0; i < jsonArray.size(); i++) {
			JsonElement jsonChild = jsonArray.get(i);
			Object child;

			if (jsonChild == null || jsonChild.isJsonNull()) {
				child = null;
			} else if (jsonChild instanceof JsonObject) {
				child = visitChildAsObject(
						$Gson$Types.getArrayComponentType(arrayType), jsonChild);
			} else if (jsonChild instanceof JsonArray) {
				child = visitChildAsArray(
						$Gson$Types.getArrayComponentType(arrayType),
						jsonChild.getAsJsonArray());
			} else if (jsonChild instanceof JsonPrimitive) {
				child = visitChildAsObject(
						$Gson$Types.getArrayComponentType(arrayType),
						jsonChild.getAsJsonPrimitive());
			} else {
				throw new IllegalStateException();
			}
			Array.set(array, i, child);
		}
	}

	// We should not implement any other method from Visitor interface since
	// all other methods should be invoked on JsonObjectDeserializationVisitor
	// instead.

	public void startVisitingObject(Object node) {
		throw new JsonParseException("Expecting array but found object: "
				+ node);
	}

	public void visitArrayField(FieldAttributes f, Type typeOfF, Object obj) {
		throw new JsonParseException("Expecting array but found array field "
				+ f.getName() + ": " + obj);
	}

	public void visitObjectField(FieldAttributes f, Type typeOfF, Object obj) {
		throw new JsonParseException("Expecting array but found object field "
				+ f.getName() + ": " + obj);
	}

	public boolean visitFieldUsingCustomHandler(FieldAttributes f,
			Type actualTypeOfField, Object parent) {
		throw new JsonParseException("Expecting array but found field "
				+ f.getName() + ": " + parent);
	}

	public void visitPrimitive(Object primitive) {
		throw new JsonParseException(
				"Type information is unavailable, and the target is not a primitive: "
						+ json);
	}
}