/**
* Copyright 2009 Google Inc.
*
* 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 org.waveprotocol.wave.model.util;
import java.util.Set;
/**
* A read only interface to a set of strings.
*
* We define this in favor of using a standard Java collections interface so
* that we can write an optimized implementation for GWT.
*
* Null is not permitted as an element. All methods, even {@link #contains(String)}
* will reject null elements.
*
* @author ohler@google.com (Christian Ohler)
*/
public interface ReadableStringSet {
/**
* A procedure that accepts an element from the set.
*/
public interface Proc {
void apply(String element);
}
/**
* Returns true iff s is in the set.
*/
boolean contains(String s);
/**
* @return some element in the set. If the set is empty, null is returned.
*/
String someElement();
/**
* Returns true iff the set is empty.
*/
boolean isEmpty();
/**
* Call the callback for each element in the map, in undefined order.
*/
void each(Proc callback);
/**
* Returns true iff every element of this is also in other.
*/
boolean isSubsetOf(ReadableStringSet other);
/**
* Returns true iff every element of this is also in other.
*/
boolean isSubsetOf(Set<String> other);
/**
* Count the number of entries in the set.
*
* Note: Depending on the underlying map implementation, this may be a
* time-consuming operation.
*/
int countEntries();
}