org.dominokit.jacksonapt.deser.collection.BaseCollectionJsonDeserializer Maven / Gradle / Ivy

Go to download
/*
 * Copyright 2013 Nicolas Morel
 *
 * 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 org.dominokit.jacksonapt.deser.collection;

import org.dominokit.jacksonapt.JsonDeserializationContext;
import org.dominokit.jacksonapt.JsonDeserializer;
import org.dominokit.jacksonapt.JsonDeserializerParameters;
import org.dominokit.jacksonapt.stream.JsonReader;
import org.dominokit.jacksonapt.stream.JsonToken;

import java.util.Collection;

/**
 * Base {@link org.dominokit.jacksonapt.JsonDeserializer} implementation for {@link java.util.Collection}.
 *
 * @param  {@link java.util.Collection} type
 * @param  Type of the elements inside the {@link java.util.Collection}
 * @author Nicolas Morel
 * @version $Id: $
 */
public abstract class BaseCollectionJsonDeserializer, T> extends BaseIterableJsonDeserializer {

    /**
     * Constructor for BaseCollectionJsonDeserializer.
     *
     * @param deserializer {@link org.dominokit.jacksonapt.JsonDeserializer} used to map the objects inside the {@link java.util.Collection}.
     */
    public BaseCollectionJsonDeserializer(JsonDeserializer deserializer) {
        super(deserializer);
    }

    /** {@inheritDoc} */
    @Override
    public C doDeserialize(JsonReader reader, JsonDeserializationContext ctx, JsonDeserializerParameters params) {
        if (JsonToken.BEGIN_ARRAY == reader.peek()) {

            C result = newCollection();

            reader.beginArray();
            while (JsonToken.END_ARRAY != reader.peek()) {
                T element = deserializer.deserialize(reader, ctx, params);
                if (isNullValueAllowed() || null != element) {
                    result.add(element);
                }
            }
            reader.endArray();

            return result;

        } else if (ctx.isAcceptSingleValueAsArray()) {

            C result = newCollection();
            result.add(deserializer.deserialize(reader, ctx, params));
            return result;

        } else {
            throw ctx.traceError("Cannot deserialize a java.util.Collection out of " + reader.peek() + " token", reader);
        }
    }

    /**
     * Instantiates a new collection for deserialization process.
     *
     * @return the new collection
     */
    protected abstract C newCollection();

    /**
     * isNullValueAllowed
     *
     * @return true if the collection accepts null value
     */
    protected boolean isNullValueAllowed() {
        return true;
    }

    /** {@inheritDoc} */
    @Override
    public void setBackReference(String referenceName, Object reference, C value, JsonDeserializationContext ctx) {
        if (null != value && !value.isEmpty()) {
            for (T val : value) {
                deserializer.setBackReference(referenceName, reference, val, ctx);
            }
        }
    }
}