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(final Set<? extends CharSequence> keys, final 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      private CharSequence lastKey = null;
043      private CharSequence curKey = findNextKey();
044
045      private CharSequence findNextKey() {
046        while (k.hasNext()) {
047          final 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
069        final T v = map.get(key);
070
071        return new Map.Entry<CharSequence, T>() {
072          @Override
073          public CharSequence getKey() {
074            return key;
075          }
076
077          @Override
078          public T getValue() {
079            return v;
080          }
081
082          @Override
083          public T setValue(final T v) {
084            throw new UnsupportedOperationException(
085                "No support for mutating values via iterator");
086          }
087        };
088      }
089
090      @Override
091      public void remove() {
092        map.remove(lastKey);
093      }
094    };
095  }
096}