ProtoList.java

/*
 * Copyright 2022 Proto Utils Authors
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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 net.morimekta.proto;

import com.google.protobuf.Descriptors;
import com.google.protobuf.MessageOrBuilder;
import net.morimekta.proto.utils.ValueUtil;

import java.util.AbstractList;
import java.util.RandomAccess;

import static java.util.Objects.requireNonNull;

/**
 * A list wrapping a repeated proto field. This is an unmodifiable list.
 *
 * @param <T> The item type.
 */
public class ProtoList<T>
        extends AbstractList<T>
        implements RandomAccess {
    private transient final MessageOrBuilder            message;
    private transient final Descriptors.FieldDescriptor field;

    /**
     * @param message Message the field is on.
     * @param field   The repeated field.
     */
    public ProtoList(MessageOrBuilder message, Descriptors.FieldDescriptor field) {
        requireNonNull(message, "message == null");
        requireNonNull(field, "field == null");
        if (!field.isRepeated() || field.isMapField()) {
            throw new IllegalArgumentException("Not a list type: " + field);
        }
        this.message = message;
        this.field = field;
    }

    @Override
    public int size() {
        return message.getRepeatedFieldCount(field);
    }

    @Override
    @SuppressWarnings("unchecked")
    public T get(int i) {
        return (T) ValueUtil.toJavaValue(field, message.getRepeatedField(field, i));
    }

    @Override
    public String toString() {
        return ValueUtil.asString(this);
    }
}