Source code

001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.reef.io.storage.util;
020
021import org.apache.reef.io.ExternalMap;
022
023import java.util.Iterator;
024import java.util.Map;
025import java.util.NoSuchElementException;
026import java.util.Set;
027
028public class GetAllIterable<T> implements
029    Iterable<Map.Entry<CharSequence, T>> {
030  private final Set<? extends CharSequence> keys;
031  private final ExternalMap<T> map;
032
033  public GetAllIterable(Set<? extends CharSequence> keys, ExternalMap<T> map) {
034    this.keys = keys;
035    this.map = map;
036  }
037
038  @Override
039  public Iterator<Map.Entry<CharSequence, T>> iterator() {
040    final Iterator<? extends CharSequence> k = keys.iterator();
041    return new Iterator<Map.Entry<CharSequence, T>>() {
042      CharSequence lastKey = null;
043      CharSequence curKey = findNextKey();
044
045      private CharSequence findNextKey() {
046        while (k.hasNext()) {
047          CharSequence next = k.next();
048          if (map.containsKey(next)) {
049            return next;
050          }
051        }
052        return null;
053      }
054
055      @Override
056      public boolean hasNext() {
057        return curKey != null;
058      }
059
060      @Override
061      public Map.Entry<CharSequence, T> next() {
062        final CharSequence key = curKey;
063        curKey = findNextKey();
064        lastKey = key;
065        if (key == null)
066          throw new NoSuchElementException();
067
068        final T v = map.get(key);
069
070        return new Map.Entry<CharSequence, T>() {
071          @Override
072          public CharSequence getKey() {
073            return key;
074          }
075
076          @Override
077          public T getValue() {
078            return v;
079          }
080
081          @Override
082          public T setValue(T v) {
083            throw new UnsupportedOperationException(
084                "No support for mutating values via iterator");
085          }
086        };
087      }
088
089      @Override
090      public void remove() {
091        map.remove(lastKey);
092      }
093    };
094  }
095}