com.spotify.apollo.ResponseImpl.java Source code

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Here is the source code for com.spotify.apollo.ResponseImpl.java

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/*
 * -\-\-
 * Spotify Apollo API Interfaces
 * --
 * Copyright (C) 2013 - 2015 Spotify AB
 * --
 * 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.spotify.apollo;

import com.google.auto.value.AutoValue;
import com.google.common.collect.ImmutableMap;

import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;

import javax.annotation.Nullable;

/**
 * An immutable response. Each invocation of a 'withXXX' method returns a new instance,
 * making it safe to share instances between threads, at the cost of some efficiency.
 */
@AutoValue
abstract class ResponseImpl<T> implements Response<T> {

    static final Response<?> OK = createInternal(Status.OK, Optional.empty());

    @Override
    public Response<T> withHeader(String header, String value) {
        // Allow overriding values
        final Map<String, String> headers = new LinkedHashMap<>();
        headers.putAll(headers());
        headers.put(header, value);

        return createInternal(status(), ImmutableMap.copyOf(headers), payload());
    }

    @Override
    public <P> Response<P> withPayload(@Nullable P newPayload) {
        return createInternal(status(), headers(), Optional.ofNullable(newPayload));
    }

    static <T> Response<T> create(StatusType statusCode) {
        Objects.requireNonNull(statusCode);

        //noinspection unchecked
        return statusCode == Status.OK ? (Response<T>) OK : createInternal(statusCode, Optional.<T>empty());
    }

    static <T> Response<T> create(StatusType statusCode, T payload) {
        Objects.requireNonNull(statusCode);
        return createInternal(statusCode, Optional.of(payload));
    }

    static <T> Response<T> create(T payload) {
        return createInternal(Status.OK, Optional.of(payload));
    }

    private static <T> Response<T> createInternal(StatusType statusCode, Optional<T> payload) {
        return createInternal(statusCode, Collections.emptyMap(), payload);
    }

    private static <T> Response<T> createInternal(StatusType statusCode, Map<String, String> headers,
            Optional<T> payload) {
        return new AutoValue_ResponseImpl<>(statusCode, headers, payload);
    }
}