io.micronaut.http.netty.stream.JsonSubscriber Maven / Gradle / Ivy

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/*
 * Copyright 2017-2020 original authors
 *
 * 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
 *
 * https://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 io.micronaut.http.netty.stream;

import io.micronaut.core.annotation.Internal;
import io.micronaut.http.netty.content.HttpContentUtil;
import io.netty.handler.codec.http.HttpContent;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Flux;

import java.util.function.Function;

/**
 * A Reactor subscriber used to handle JSON content. It delegates to an upstream subscriber, wrapping them with opening/closing brackets
 * where necessary.
 */
@Internal
public final class JsonSubscriber {
    public static Flux lift(Publisher publisher) {
        HttpContent closeBracket = HttpContentUtil.closeBracket();
        return Flux.from(publisher)
            .concatWithValues(closeBracket)
            .map(new Function<>() {
                boolean empty = true;

                @Override
                public HttpContent apply(HttpContent httpContent) {
                    if (empty) {
                        empty = false;
                        return HttpContentUtil.prefixOpenBracket(httpContent);
                    } else if (httpContent != closeBracket) {
                        return HttpContentUtil.prefixComma(httpContent);
                    } else {
                        return httpContent;
                    }
                }
            });
    }
}