| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.apache.jena.atlas.iterator; |
| |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| import java.util.function.Consumer; |
| import java.util.function.Function; |
| import java.util.stream.Stream; |
| |
| /** flatMap iterator. |
| * See {@link Stream#flatMap} |
| */ |
| /*package*/ class IteratorFlatMap<IN,OUT> implements IteratorCloseable<OUT> { |
| private boolean finished = false; |
| private Iterator<OUT> current = null; |
| private Iterator<IN> input; |
| final private Function<IN, Iterator<OUT>> mapper; |
| |
| /*package*/ IteratorFlatMap(Iterator<IN> iter, Function<IN, Iterator<OUT>> mapper) { |
| this.input = iter; |
| this.mapper = mapper; |
| } |
| |
| @Override |
| public boolean hasNext() { |
| if ( finished ) |
| return false; |
| // !finished and current == null : happens at the start. |
| if ( current != null ) { |
| if ( current.hasNext() ) |
| return true; |
| // Move next in the input. |
| Iter.close(current); |
| current = null; |
| } |
| // Stage finished or this is the first call. |
| while ( input.hasNext() ) { |
| IN x = input.next(); |
| current = mapper.apply(x); |
| if ( current == null ) |
| continue; |
| if ( ! current.hasNext() ) { |
| Iter.close(current); |
| continue; |
| } |
| // There is at least one item in the new current stage. |
| return true; |
| } |
| if ( current != null ) |
| Iter.close(current); |
| // Nothing more. |
| current = null; |
| finished = true; |
| return false; |
| } |
| |
| @Override |
| public OUT next() { |
| if ( !hasNext() ) |
| throw new NoSuchElementException(); |
| return current.next(); |
| } |
| |
| @Override |
| public void forEachRemaining(Consumer<? super OUT> action) { |
| if ( finished ) |
| return; |
| if ( current != null ) { |
| current.forEachRemaining(action); |
| Iter.close(current); |
| current = null; |
| } |
| input.forEachRemaining(x->{ |
| current = mapper.apply(x); |
| if ( current == null ) |
| return; |
| current.forEachRemaining(action); |
| Iter.close(current); |
| }); |
| current = null; |
| } |
| |
| @Override |
| public void close() { |
| if ( current != null ) |
| Iter.close(current); |
| Iter.close(input); |
| } |
| } |