module java.util.Collection;

import java.lang.all;
import java.util.Iterator;

interface Collection {
    public bool     add(Object o);
    public bool     add(String o);
    public bool    addAll(Collection c);
    public void   clear();
    public bool    contains(Object o);
    public bool    containsAll(Collection c);
    public int    opEquals(Object o);
    public hash_t   toHash();
    public bool    isEmpty();
    public Iterator   iterator();
    public bool    remove(Object o);
    public bool    remove(String o);
    public bool    removeAll(Collection c);
    public bool    retainAll(Collection c);
    public int    size();
    public Object[]   toArray();
    public Object[]   toArray(Object[] a);

    // only for D
    public int opApply (int delegate(ref Object value) dg);
}