Optimize ConcatenatedListView's Iterator and fix hidden CreativeTabs taking up page space.

src/main/java/net/minecraftforge/common/util/ConcatenatedListView.java

@@ -5,11 +5,17 @@
 
 package net.minecraftforge.common.util;
 
-import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+import java.util.NoSuchElementException;
 import java.util.function.Supplier;
 
 /**
@@ -18,16 +24,13 @@ import java.util.function.Supplier;
  * for each of your collections.<p/>
  * This list does not support modification operations, but the underlying lists may be mutated safely externally.
  */
-public class ConcatenatedListView<T> implements List<T>
-{
+public class ConcatenatedListView<T> implements List<T> {
     @SafeVarargs
-    public static <T> ConcatenatedListView<T> of(List<T>... lists)
-    {
+    public static <T> ConcatenatedListView<T> of(List<T>... lists) {
         return new ConcatenatedListView<>(List.of(lists));
     }
 
-    public static <T> List<T> of(List<? extends List<? extends T>> members)
-    {
+    public static <T> List<T> of(List<? extends List<? extends T>> members) {
         return switch (members.size()) {
             case 0 -> List.of();
             case 1 -> Collections.unmodifiableList(members.getFirst());
@@ -37,14 +40,12 @@ public class ConcatenatedListView<T> implements List<T>
 
     private final List<? extends List<? extends T>> lists;
 
-    private ConcatenatedListView(List<? extends List<? extends T>> lists)
-    {
+    private ConcatenatedListView(List<? extends List<? extends T>> lists) {
         this.lists = lists;
     }
 
     @Override
-    public int size()
-    {
+    public int size() {
         int size = 0;
         for (var list : lists)
             size += list.size();
@@ -52,8 +53,7 @@ public class ConcatenatedListView<T> implements List<T>
     }
 
     @Override
-    public boolean isEmpty()
-    {
+    public boolean isEmpty() {
         for (List<? extends T> list : lists)
             if (!list.isEmpty())
                 return false;
@@ -61,8 +61,7 @@ public class ConcatenatedListView<T> implements List<T>
     }
 
     @Override
-    public boolean contains(Object o)
-    {
+    public boolean contains(Object o) {
         for (var list : lists)
             if (list.contains(o))
                 return true;
@@ -70,10 +69,8 @@ public class ConcatenatedListView<T> implements List<T>
     }
 
     @Override
-    public T get(int index)
-    {
-        for (var list : lists)
-        {
+    public T get(int index) {
+        for (var list : lists) {
             int size = list.size();
             if (index < size)
                 return list.get(index);
@@ -83,11 +80,9 @@ public class ConcatenatedListView<T> implements List<T>
     }
 
     @Override
-    public int indexOf(Object o)
-    {
+    public int indexOf(Object o) {
         int offset = 0;
-        for (var list : lists)
-        {
+        for (var list : lists) {
             int foundIndex = list.indexOf(o);
             if (foundIndex >= 0)
                 return offset + foundIndex;
@@ -97,11 +92,9 @@ public class ConcatenatedListView<T> implements List<T>
     }
 
     @Override
-    public int lastIndexOf(Object o)
-    {
+    public int lastIndexOf(Object o) {
         int offset = 0;
-        for (var list : Lists.reverse(lists))
-        {
+        for (var list : Lists.reverse(lists)) {
             int foundIndex = list.lastIndexOf(o);
             if (foundIndex >= 0)
                 return offset + foundIndex;
@@ -112,25 +105,42 @@ public class ConcatenatedListView<T> implements List<T>
 
     @NotNull
     @Override
-    public Iterator<T> iterator()
-    {
-        return Iterables.unmodifiableIterable(Iterables.concat(lists)).iterator();
-    }
+    public Iterator<T> iterator() {
+        return new Iterator<T>() {
+            private Iterator<? extends List<? extends T>> listItr = lists.iterator();
+            private Iterator<? extends T> current;
 
-    @Override
-    public Spliterator<T> spliterator()
-    {
-        return Iterables.unmodifiableIterable(Iterables.concat(lists)).spliterator();
+            @Override
+            public boolean hasNext() {
+                while ((current == null || !current.hasNext()) && listItr.hasNext()) {
+                    var nextList = listItr.next();
+                    if (nextList != null)
+                        current = nextList.iterator();
+                }
+                return current != null;
+            }
+
+            @Override
+            public T next() {
+                if (!hasNext())
+                    throw new NoSuchElementException();
+                T next = current.next();
+                if (!current.hasNext())
+                    current = null;
+                return next;
+            }
+
+        };
     }
 
     // Delegate to a concatenated collection
-    private <C extends Collection<T>> C concatenate(Supplier<C> collectionFactory)
-    {
+    private <C extends Collection<T>> C concatenate(Supplier<C> collectionFactory) {
         var concat = collectionFactory.get();
         for (var list : lists)
             concat.addAll(list);
         return concat;
     }
+
     @NotNull @Override public Object[] toArray() { return concatenate(ArrayList::new).toArray(); }
     @NotNull @Override public <T1> T1[] toArray(@NotNull T1[] a) { return concatenate(ArrayList::new).toArray(a); }
     @Override public boolean containsAll(@NotNull Collection<?> c) { return concatenate(HashSet::new).containsAll(c); }