content: /*
   * Copyright 2016 HuntBugs contributors
   * 
   * 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 one.util.huntbugs.util;
  
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  
  /**
   * @author lan
   *
   */
  public class Iterables {
      public static <T> Iterable<T> concat(Iterable<? extends T> it1, Iterable<? extends T> it2) {
          return () -> new Iterator<T>() {
              boolean first = true;
              Iterator<? extends T> it = it1.iterator();
  
              @Override
              public boolean hasNext() {
                  boolean hasNext = it.hasNext();
                  if(hasNext)
                      return true;
                  if(first) {
                      first = false;
                      it = it2.iterator();
                      return hasNext();
                  }
                  return false;
              }
  
              @Override
              public T next() {
                  if(first) {
                      hasNext();
                  }
                  return it.next();
              }
          };
      }
      
      public static <T> List<T> toList(Iterable<T> iterable) {
          List<T> list = new ArrayList<>();
          iterable.forEach(list::add);
          return list;
      }
  }
  