MetadataStoreBase.java

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package org.bukkit.metadata;

import org.apache.commons.lang.Validate;
import org.bukkit.plugin.Plugin;

import java.util.*;

public abstract class MetadataStoreBase<T> {
    private Map<String, List<MetadataValue>> metadataMap = new HashMap<String, List<MetadataValue>>();
    private WeakHashMap<T, Map<String, String>> disambiguationCache = new WeakHashMap<T, Map<String, String>>();

    public synchronized void setMetadata(T subject, String metadataKey, MetadataValue newMetadataValue) {
        Validate.notNull(newMetadataValue, "Value cannot be null");
        Validate.notNull(newMetadataValue.getOwningPlugin(), "Plugin cannot be null");
        String key = cachedDisambiguate(subject, metadataKey);
        if (!metadataMap.containsKey(key)) {
            metadataMap.put(key, new ArrayList<MetadataValue>());
        }
        // we now have a list of subject's metadata for the given metadata key. If newMetadataValue's owningPlugin
        // is found in this list, replace the value rather than add a new one.
        List<MetadataValue> metadataList = metadataMap.get(key);
        for (int i = 0; i < metadataList.size(); i++) {
            if (metadataList.get(i).getOwningPlugin().equals(newMetadataValue.getOwningPlugin())) {
                metadataList.set(i, newMetadataValue);
                return;
            }
        }
        // we didn't find a duplicate...add the new metadata value
        metadataList.add(newMetadataValue);
    }

    public synchronized List<MetadataValue> getMetadata(T subject, String metadataKey) {
        String key = cachedDisambiguate(subject, metadataKey);
        if (metadataMap.containsKey(key)) {
            return Collections.unmodifiableList(metadataMap.get(key));
        } else {
            return Collections.emptyList();
        }
    }

    public synchronized boolean hasMetadata(T subject, String metadataKey) {
        String key = cachedDisambiguate(subject, metadataKey);
        return metadataMap.containsKey(key);
    }

    public synchronized void removeMetadata(T subject, String metadataKey, Plugin owningPlugin) {
        Validate.notNull(owningPlugin, "Plugin cannot be null");
        String key = cachedDisambiguate(subject, metadataKey);
        List<MetadataValue> metadataList = metadataMap.get(key);
        if (metadataList == null) return;
        for (int i = 0; i < metadataList.size(); i++) {
            if (metadataList.get(i).getOwningPlugin().equals(owningPlugin)) {
                metadataList.remove(i);
                if (metadataList.isEmpty()) {
                    metadataMap.remove(key);
                }
            }
        }
    }

    public synchronized void invalidateAll(Plugin owningPlugin) {
        Validate.notNull(owningPlugin, "Plugin cannot be null");
        for (List<MetadataValue> values : metadataMap.values()) {
            for (MetadataValue value : values) {
                if (value.getOwningPlugin().equals(owningPlugin)) {
                    value.invalidate();
                }
            }
        }
    }

    private String cachedDisambiguate(T subject, String metadataKey) {
        if (disambiguationCache.containsKey(subject) && disambiguationCache.get(subject).containsKey(metadataKey)) {
            return disambiguationCache.get(subject).get(metadataKey);
        } else {
            if (!disambiguationCache.containsKey(subject)) {
                disambiguationCache.put(subject, new HashMap<String, String>());
            }
            String disambiguation = disambiguate(subject, metadataKey);
            disambiguationCache.get(subject).put(metadataKey, disambiguation);
            return disambiguation;
        }
    }

    protected abstract String disambiguate(T subject, String metadataKey);
}