id stack

lib/android/app/src/main/java/com/reactnativenavigation/utils/IdStack.java

 package com.reactnativenavigation.utils;
 
 import java.util.ArrayDeque;
+import java.util.Deque;
 import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
 
-public class IdStack<E> {
+public class IdStack<E> implements Iterable<String> {
 
 	private final ArrayDeque<String> deque = new ArrayDeque<>();
 	private final HashMap<String, E> map = new HashMap<>();
 	}
 
 	public E peek() {
+		if (isEmpty()) {
+			return null;
+		}
 		return map.get(deque.peek());
 	}
 
 	public E pop() {
-		if (deque.isEmpty()) {
+		if (isEmpty()) {
 			return null;
 		}
-		String popped = deque.pop();
-		E removed = map.remove(popped);
-		return removed;
+		return map.remove(deque.pop());
 	}
 
 	public boolean isEmpty() {
 		return map.get(id);
 	}
 
-	public boolean contains(final String id) {
+	public boolean containsId(final String id) {
 		return deque.contains(id);
 	}
+
+	public E remove(final String id) {
+		if (!containsId(id)) {
+			return null;
+		}
+		deque.remove(id);
+		return map.remove(id);
+	}
+
+	@Override
+	public Iterator<String> iterator() {
+		return deque.iterator();
+	}
+
+	public Deque<String> getIds() {
+		return deque;
+	}
+
+	public Map<String, E> getMap() {
+		return map;
+	}
 }

lib/android/app/src/test/java/com/reactnativenavigation/utils/IndexedStackTest.java

 
 import org.junit.Test;
 
+import java.util.Deque;
+import java.util.Map;
+
 import static org.assertj.core.api.Java6Assertions.assertThat;
 
 public class IndexedStackTest extends BaseTest {
 
 	@Test
 	public void containsId() throws Exception {
-		assertThat(uut.contains("123")).isFalse();
+		assertThat(uut.containsId("123")).isFalse();
+		uut.push("123", 123);
+		assertThat(uut.containsId("123")).isTrue();
+	}
+
+	@Test
+	public void remove() throws Exception {
+		assertThat(uut.remove("123")).isNull();
+
+		uut.push("123", 123);
+		uut.push("456", 456);
+
+		assertThat(uut.remove("123")).isEqualTo(123);
+	}
+
+	@Test
+	public void iterableIds() throws Exception {
+		assertThat(uut).isInstanceOf(Iterable.class);
+		assertThat(uut).isEmpty();
 		uut.push("123", 123);
-		assertThat(uut.contains("123")).isTrue();
+		uut.push("456", 456);
+		assertThat(uut).containsExactly("456", "123");
+	}
 
+	@Test
+	public void getIdDeque() throws Exception {
+		assertThat(uut.getIds()).isNotNull().isInstanceOf(Deque.class).isEmpty();
+	}
+
+	@Test
+	public void getMap() throws Exception {
+		assertThat(uut.getMap()).isNotNull().isInstanceOf(Map.class).isEmpty();
 	}
 }