org.bukkit.craftbukkit.util.WeakCollection Maven / Gradle / Ivy

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package org.bukkit.craftbukkit.util;

import org.apache.commons.lang.Validate;

import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;

public final class WeakCollection implements Collection {
  static final Object NO_VALUE = new Object();
  private final Collection> collection;

  public WeakCollection() {
    collection = new ArrayList>();
  }

  public boolean add(T value) {
    Validate.notNull(value, "Cannot add null value");
    return collection.add(new WeakReference(value));
  }

  public boolean addAll(Collection collection) {
    Collection> values = this.collection;
    boolean ret = false;
    for (T value : collection) {
      Validate.notNull(value, "Cannot add null value");
      ret |= values.add(new WeakReference(value));
    }
    return ret;
  }

  public void clear() {
    collection.clear();
  }

  public boolean contains(Object object) {
    if (object == null) {
      return false;
    }
    for (T compare : this) {
      if (object.equals(compare)) {
        return true;
      }
    }
    return false;
  }

  public boolean containsAll(Collection collection) {
    return toCollection().containsAll(collection);
  }

  public boolean isEmpty() {
    return !iterator().hasNext();
  }

  public Iterator iterator() {
    return new Iterator() {
      final Iterator> it = collection.iterator();
      Object value = NO_VALUE;

      public boolean hasNext() {
        Object value = this.value;
        if (value != null && value != NO_VALUE) {
          return true;
        }

        Iterator> it = this.it;
        value = null;

        while (it.hasNext()) {
          WeakReference ref = it.next();
          value = ref.get();
          if (value == null) {
            it.remove();
          } else {
            this.value = value;
            return true;
          }
        }
        return false;
      }

      public T next() throws NoSuchElementException {
        if (!hasNext()) {
          throw new NoSuchElementException("No more elements");
        }

        @SuppressWarnings("unchecked")
        T value = (T) this.value;
        this.value = NO_VALUE;
        return value;
      }

      public void remove() throws IllegalStateException {
        if (value != NO_VALUE) {
          throw new IllegalStateException("No last element");
        }

        value = null;
        it.remove();
      }
    };
  }

  public boolean remove(Object object) {
    if (object == null) {
      return false;
    }

    Iterator it = this.iterator();
    while (it.hasNext()) {
      if (object.equals(it.next())) {
        it.remove();
        return true;
      }
    }
    return false;
  }

  public boolean removeAll(Collection collection) {
    Iterator it = this.iterator();
    boolean ret = false;
    while (it.hasNext()) {
      if (collection.contains(it.next())) {
        ret = true;
        it.remove();
      }
    }
    return ret;
  }

  public boolean retainAll(Collection collection) {
    Iterator it = this.iterator();
    boolean ret = false;
    while (it.hasNext()) {
      if (!collection.contains(it.next())) {
        ret = true;
        it.remove();
      }
    }
    return ret;
  }

  public int size() {
    int s = 0;
    for (T value : this) {
      s++;
    }
    return s;
  }

  public Object[] toArray() {
    return this.toArray(new Object[0]);
  }

  public  T[] toArray(T[] array) {
    return toCollection().toArray(array);
  }

  private Collection toCollection() {
    ArrayList collection = new ArrayList();
    for (T value : this) {
      collection.add(value);
    }
    return collection;
  }
}