diff --git a/src/zutil/struct/MultiIterator.java b/src/zutil/struct/MultiIterator.java new file mode 100644 index 0000000..d6937a8 --- /dev/null +++ b/src/zutil/struct/MultiIterator.java @@ -0,0 +1,77 @@ +/* + * The MIT License (MIT) + * + * Copyright (c) 2020 Ziver Koc + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +package zutil.struct; + +import java.util.Iterator; +import java.util.LinkedList; +import java.util.NoSuchElementException; +import java.util.Queue; + +/** + * This class is a wrapper that combine multiple Iterators of same type. + * This class will start by iterating through the first Iterator until the + * end of it has been reach and then the next iterator will be used until + * all iterators no longer has any items. + */ +public class MultiIterator implements Iterator { + private Queue> queue = new LinkedList<>(); + + + public void addIterator(Iterator it) { + queue.add(it); + } + + + @Override + public boolean hasNext() { + if (queue.isEmpty()) + return false; + else { + if (!queue.peek().hasNext()) { + queue.poll(); + return hasNext(); + } + + return true; + } + } + + @Override + public T next() { + if (!hasNext()) + throw new NoSuchElementException("End of iterator has been reached."); + else { + return queue.peek().next(); + } + } + + @Override + public void remove() { + if (queue.isEmpty()) + return; + + queue.peek().remove(); + } +} diff --git a/test/zutil/struct/MultiIteratorTest.java b/test/zutil/struct/MultiIteratorTest.java new file mode 100644 index 0000000..6b38880 --- /dev/null +++ b/test/zutil/struct/MultiIteratorTest.java @@ -0,0 +1,76 @@ +/* + * The MIT License (MIT) + * + * Copyright (c) 2020 Ziver Koc + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +package zutil.struct; + +import org.junit.Test; + +import java.util.Arrays; +import java.util.NoSuchElementException; + +import static org.junit.Assert.*; + +public class MultiIteratorTest { + + @Test(expected = NoSuchElementException.class) + public void emptyTest() { + MultiIterator it = new MultiIterator<>(); + assertEquals(false, it.hasNext()); + it.next(); // NoSuchElementException + } + + @Test + public void oneIteratorTest() { + MultiIterator it = new MultiIterator<>(); + it.addIterator(Arrays.asList("value1", "value2").iterator()); + + assertEquals(true, it.hasNext()); + assertEquals("value1", it.next()); + + assertEquals(true, it.hasNext()); + assertEquals("value2", it.next()); + + assertEquals(false, it.hasNext()); + } + + @Test + public void multiIteratorTest() { + MultiIterator it = new MultiIterator<>(); + it.addIterator(Arrays.asList("value1", "value2").iterator()); + it.addIterator(Arrays.asList("value3", "value4").iterator()); + it.addIterator(Arrays.asList("value5", "value6").iterator()); + + assertEquals("value1", it.next()); + assertEquals("value2", it.next()); + + assertEquals(true, it.hasNext()); + assertEquals("value3", it.next()); + assertEquals("value4", it.next()); + + assertEquals("value5", it.next()); + assertEquals("value6", it.next()); + + assertEquals(false, it.hasNext()); + } +} \ No newline at end of file