com.getperka.flatpack.codexes.CollectionCodex.java Source code

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Here is the source code for com.getperka.flatpack.codexes.CollectionCodex.java

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/*
 * #%L
 * FlatPack serialization code
 * %%
 * Copyright (C) 2012 Perka 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.
 * #L%
 */
package com.getperka.flatpack.codexes;

import java.io.IOException;
import java.util.Collection;

import javax.inject.Inject;

import com.getperka.flatpack.ext.Codex;
import com.getperka.flatpack.ext.DeserializationContext;
import com.getperka.flatpack.ext.JsonKind;
import com.getperka.flatpack.ext.SerializationContext;
import com.getperka.flatpack.ext.Type;
import com.getperka.flatpack.ext.TypeContext;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.stream.JsonWriter;
import com.google.inject.TypeLiteral;

/**
 * A base type to serialize a collection of objects as an array.
 * 
 * @param <T> the type of collection to be serialized
 * @param <V> the value type contained in the collection
 */
public abstract class CollectionCodex<T extends Collection<V>, V> extends Codex<T> {
    /**
     * Initialized in {@link #setType(TypeLiteral, TypeContext)} so subclasses need not call an
     * explicit super-constructor.
     */
    private Codex<V> valueCodex;

    protected CollectionCodex() {
    }

    @Override
    public Type describe() {
        return new Type.Builder().withJsonKind(JsonKind.LIST).withListElement(valueCodex.describe()).build();
    }

    @Override
    public String getPropertySuffix() {
        return valueCodex.getPropertySuffix();
    }

    @Override
    public T readNotNull(JsonElement element, DeserializationContext context) throws Exception {
        T toReturn = newCollection();
        JsonArray array = element.getAsJsonArray();
        int count = 0;
        for (JsonElement elt : array) {
            context.pushPath("[" + count++ + "]");
            toReturn.add(valueCodex.read(elt, context));
            context.popPath();
        }
        return toReturn;
    }

    @Override
    public void scanNotNull(T collection, SerializationContext context) throws Exception {
        int count = 0;
        for (V t : collection) {
            context.pushPath("[" + count++ + "]");
            valueCodex.scan(t, context);
            context.popPath();
        }
    }

    @Override
    public void writeNotNull(T collection, SerializationContext context) throws IOException {
        JsonWriter writer = context.getWriter();
        writer.beginArray();
        int count = 0;
        for (V t : collection) {
            context.pushPath("[" + count++ + "]");
            valueCodex.write(t, context);
            context.popPath();
        }
        writer.endArray();
    }

    protected abstract T newCollection();

    @Inject
    @SuppressWarnings("unchecked")
    void setType(TypeLiteral<V> valueType, TypeContext context) {
        valueCodex = (Codex<V>) context.getCodex(valueType.getType());
    }
}