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Parameter Source

There is a newer version: 1.0

package com.laamella.parameter_source;

import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
import java.util.function.Function;

/**
 * Basic caching for any parameter source.
 * Keeps values in cache until flush() is called.
 */
public class CachingParameterSource implements ParameterSource {
    private final Cache> stringValueCache;
    private final Cache> integerValueCache;
    private final Cache> objectValueCache;

    public CachingParameterSource(ParameterSource cachedParameterSource) {
        stringValueCache = new Cache<>(cachedParameterSource::getOptionalString);
        integerValueCache = new Cache<>(cachedParameterSource::getOptionalInteger);
        objectValueCache = new Cache<>(cachedParameterSource::getOptionalObject);
    }

    private static class Cache {
        private final Map content = new HashMap();
        private final Function freshValueSource;

        public Cache(Function freshValueSource) {
            this.freshValueSource = freshValueSource;
        }

        public V get(K key) {
            return content.computeIfAbsent(key, freshValueSource);
        }

        public void flush() {
            content.clear();
        }
    }

    @Override
    public Optional getOptionalString(String key) {
        return stringValueCache.get(key);
    }

    @Override
    public Optional getOptionalInteger(String key) {
        return integerValueCache.get(key);
    }

    @Override
    public Optional