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Palantir open source project

There is a newer version: 4.8.0-rc1

/*
 * (c) Copyright 2024 Palantir Technologies Inc. All rights reserved.
 *
 * 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.palantir.dialogue.core;

import com.palantir.logsafe.Preconditions;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Supplier;

final class ChannelState {
    static final class Key {
        private final Class valueClass;
        private final Supplier factory;

        private T cast(final Object value) {
            return valueClass.cast(value);
        }

        private Supplier getFactory() {
            return factory;
        }

        Key(final Class valueClass, Supplier factory) {
            this.valueClass = valueClass;
            this.factory = factory;
        }
    }

    @SuppressWarnings("DangerousIdentityKey")
    private final Map, Object> state = new HashMap<>();

     T getState(Key key) {
        return key.cast(Preconditions.checkNotNull(
                state.computeIfAbsent(key, keyValue -> keyValue.getFactory().get()),
                "state factory cannot produce a null value"));
    }
}