Polishing

This is a follow-on to https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/bazel-dev/Q2owiR-e86s/ugrVUhn7AwAJ to introduce more usages of Java 8 idioms and other "cleanups", with the intention of making the code base easier to maintain.

Closes #3623.

PiperOrigin-RevId: 167566256

11 files changed, 103 insertions, 189 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/collect/CollectionUtils.java b/src/main/java/com/google/devtools/build/lib/collect/CollectionUtils.java
index 341e750b87..dc33350d6e 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/CollectionUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/CollectionUtils.java
@@ -13,14 +13,17 @@
 // limitations under the License.
 package com.google.devtools.build.lib.collect;
 
-import static com.google.common.collect.Sets.newEnumSet;
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static java.util.stream.Collectors.toCollection;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Maps;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.util.Preconditions;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.EnumSet;
@@ -28,6 +31,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 
 /**
@@ -106,13 +110,7 @@ public final class CollectionUtils {
    */
   @SuppressWarnings("unchecked")
   public static <T> ImmutableList<T> asListWithoutNulls(T... elements) {
-    ImmutableList.Builder<T> builder = ImmutableList.builder();
-    for (T element : elements) {
-      if (element != null) {
-        builder.add(element);
-      }
-    }
-    return builder.build();
+    return Arrays.stream(elements).filter(Objects::nonNull).collect(toImmutableList());
   }
 
   /**
@@ -139,11 +137,7 @@ public final class CollectionUtils {
    * Given an iterable, returns an immutable iterable with the same contents.
    */
   public static <T> Iterable<T> makeImmutable(Iterable<T> iterable) {
-    if (isImmutable(iterable)) {
-      return iterable;
-    } else {
-      return ImmutableList.copyOf(iterable);
-    }
+    return isImmutable(iterable) ? iterable : ImmutableList.copyOf(iterable);
   }
 
   /**
@@ -178,14 +172,9 @@ public final class CollectionUtils {
   public static <T extends Enum<T>> EnumSet<T> fromBits(int value, Class<T> clazz) {
     T[] elements = clazz.getEnumConstants();
     Preconditions.checkArgument(elements.length <= 32);
-    ArrayList<T> result = new ArrayList<>();
-    for (T element : elements) {
-      if ((value & (1 << element.ordinal())) != 0) {
-        result.add(element);
-      }
-    }
-
-    return newEnumSet(result, clazz);
+    return Arrays.stream(elements)
+        .filter(element -> (value & (1 << element.ordinal())) != 0)
+        .collect(toCollection(() -> EnumSet.noneOf(clazz)));
   }
 
   /**
@@ -200,11 +189,7 @@ public final class CollectionUtils {
    */
   public static <KEY_1, KEY_2, VALUE> ImmutableMap<KEY_1, ImmutableMap<KEY_2, VALUE>> toImmutable(
       Map<KEY_1, Map<KEY_2, VALUE>> map) {
-    ImmutableMap.Builder<KEY_1, ImmutableMap<KEY_2, VALUE>> builder = ImmutableMap.builder();
-    for (Map.Entry<KEY_1, Map<KEY_2, VALUE>> entry : map.entrySet()) {
-      builder.put(entry.getKey(), ImmutableMap.copyOf(entry.getValue()));
-    }
-    return builder.build();
+    return ImmutableMap.copyOf(Maps.transformValues(map, ImmutableMap::copyOf));
   }
 
   /**
@@ -212,10 +197,6 @@ public final class CollectionUtils {
    */
   public static <KEY_1, KEY_2, VALUE> Map<KEY_1, Map<KEY_2, VALUE>> copyOf(
       Map<KEY_1, ? extends Map<KEY_2, VALUE>> map) {
-    Map<KEY_1, Map<KEY_2, VALUE>> result = new HashMap<>();
-    for (Map.Entry<KEY_1, ? extends Map<KEY_2, VALUE>> entry : map.entrySet()) {
-      result.put(entry.getKey(), new HashMap<>(entry.getValue()));
-    }
-    return result;
+    return new HashMap<>(Maps.transformValues(map, HashMap::new));
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/collect/CompactHashSet.java b/src/main/java/com/google/devtools/build/lib/collect/CompactHashSet.java
index 88bfc84a81..6a81f2675f 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/CompactHashSet.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/CompactHashSet.java
@@ -31,7 +31,6 @@ package com.google.devtools.build.lib.collect;
 
 import com.google.common.primitives.Ints;
 import com.google.devtools.build.lib.util.Preconditions;
-
 import java.io.IOException;
 import java.io.InvalidObjectException;
 import java.io.ObjectInputStream;
@@ -46,7 +45,6 @@ import java.util.ConcurrentModificationException;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.Objects;
-
 import javax.annotation.Nullable;
 
 /**
@@ -113,7 +111,7 @@ public class CompactHashSet<E> extends AbstractSet<E> implements Serializable {
    * Creates an empty {@code CompactHashSet} instance.
    */
   public static <E> CompactHashSet<E> create() {
-    return new CompactHashSet<E>();
+    return new CompactHashSet<>();
   }
 
   /**
@@ -153,7 +151,7 @@ public class CompactHashSet<E> extends AbstractSet<E> implements Serializable {
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
   public static <E> CompactHashSet<E> createWithExpectedSize(int expectedSize) {
-    return new CompactHashSet<E>(expectedSize);
+    return new CompactHashSet<>(expectedSize);
   }
 
   private static final int MAXIMUM_CAPACITY = 1 << 30;
diff --git a/src/main/java/com/google/devtools/build/lib/collect/EquivalenceRelation.java b/src/main/java/com/google/devtools/build/lib/collect/EquivalenceRelation.java
index 7a7517794c..af379d02c3 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/EquivalenceRelation.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/EquivalenceRelation.java
@@ -15,29 +15,28 @@
 package com.google.devtools.build.lib.collect;
 
 /**
- * A comparison function, which imposes an equivalence relation on some
- * collection of objects.
+ * A comparison function, which imposes an equivalence relation on some collection of objects.
  *
- * <p>The ordering imposed by an EquivalenceRelation <tt>e</tt> on a set of
- * elements <tt>S</tt> is said to be <i>consistent with equals</i> if and only
- * if <tt>(compare((Object)e1, (Object)e2)==0)</tt> has the same boolean value
- * as <tt>e1.equals((Object)e2)</tt> for every <tt>e1</tt> and <tt>e2</tt> in
- * <tt>S</tt>.<p>
+ * <p>The ordering imposed by an EquivalenceRelation <tt>e</tt> on a set of elements <tt>S</tt> is
+ * said to be <i>consistent with equals</i> if and only if <tt>(compare((Object)e1,
+ * (Object)e2)==0)</tt> has the same boolean value as <tt>e1.equals((Object)e2)</tt> for every
+ * <tt>e1</tt> and <tt>e2</tt> in <tt>S</tt>.
  *
- * <p>Unlike {@link java.util.Comparator}, whose implementations are often
- * consistent with equals, the applications for which EquivalenceRelation
- * instances are used means that its implementations rarely are.  They may are
- * usually more or less discriminative than the default equivalence relation
- * for the type.
+ * <p>
  *
- * <p>For example, consider possible equivalence relations for {@link
- * java.lang.Integer}: the default equivalence defined by Integer.equals() is
- * based on the integer value is represents, but two alternative equivalences
- * would be {@link EquivalenceRelation#IDENTITY} (object identity&mdash;a more
- * discriminative relation) or <i>parity</i> (under which all even numbers, odd
- * numbers are considered equivalent to each other&mdash;a less discriminative
- * relation).
+ * <p>Unlike {@link java.util.Comparator}, whose implementations are often consistent with equals,
+ * the applications for which EquivalenceRelation instances are used means that its implementations
+ * rarely are. They may are usually more or less discriminative than the default equivalence
+ * relation for the type.
+ *
+ * <p>For example, consider possible equivalence relations for {@link java.lang.Integer}: the
+ * default equivalence defined by Integer.equals() is based on the integer value is represents, but
+ * two alternative equivalences would be {@link EquivalenceRelation#IDENTITY} (object
+ * identity&mdash;a more discriminative relation) or <i>parity</i> (under which all even numbers,
+ * odd numbers are considered equivalent to each other&mdash;a less discriminative relation).
  */
+// TODO: Consider phasing out this interface in favour of com.google.common.base.Equivalence
+@FunctionalInterface
 public interface EquivalenceRelation<T> {
   // This should be a superinterface of Comparator.
 
@@ -64,30 +63,16 @@ public interface EquivalenceRelation<T> {
   int compare(T o1, T o2);
 
   /**
-   * The object-identity equivalence relation.  This is the strictest possible
-   * equivalence relation for objects, and considers two values equal iff they
-   * are references to the same object instance.
+   * The object-identity equivalence relation. This is the strictest possible equivalence relation
+   * for objects, and considers two values equal iff they are references to the same object
+   * instance.
    */
-  public static final EquivalenceRelation<?> IDENTITY =
-      new EquivalenceRelation<Object>() {
-        @Override
-        public int compare(Object o1, Object o2) {
-          return o1 == o2 ? 0 : -1;
-        }
-      };
+  EquivalenceRelation<?> IDENTITY = (EquivalenceRelation<Object>) (o1, o2) -> (o1 == o2) ? 0 : -1;
 
   /**
-   * The default equivalence relation for type T, using T.equals().  This
-   * relation considers two values equivalent if either they are both null, or
-   * o1.equals(o2).
+   * The default equivalence relation for type T, using T.equals(). This relation considers two
+   * values equivalent if either they are both null, or o1.equals(o2).
    */
-  public static final EquivalenceRelation<?> DEFAULT =
-      new EquivalenceRelation<Object>() {
-        @Override
-        public int compare(Object o1, Object o2) {
-          return (o1 == null ? o2 == null : o1.equals(o2))
-              ? 0
-              : -1;
-        }
-      };
+  EquivalenceRelation<?> DEFAULT =
+      (EquivalenceRelation<Object>) (o1, o2) -> (o1 == null ? o2 == null : o1.equals(o2)) ? 0 : -1;
 }
diff --git a/src/main/java/com/google/devtools/build/lib/collect/ImmutableSortedKeyListMultimap.java b/src/main/java/com/google/devtools/build/lib/collect/ImmutableSortedKeyListMultimap.java
index 1e164891f1..0fc427bb7f 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/ImmutableSortedKeyListMultimap.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/ImmutableSortedKeyListMultimap.java
@@ -21,8 +21,8 @@ import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Multiset;
+import com.google.common.primitives.Ints;
 import com.google.devtools.build.lib.util.Preconditions;
-
 import java.util.AbstractCollection;
 import java.util.AbstractMap;
 import java.util.AbstractMap.SimpleImmutableEntry;
@@ -34,7 +34,6 @@ import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-
 import javax.annotation.Nullable;
 
 /**
@@ -122,10 +121,7 @@ public final class ImmutableSortedKeyListMultimap<K extends Comparable<K>, V>
     }
 
     public Builder<K, V> putAll(Multimap<? extends K, ? extends V> multimap) {
-      for (Map.Entry<? extends K, ? extends Collection<? extends V>> entry
-          : multimap.asMap().entrySet()) {
-        putAll(entry.getKey(), entry.getValue());
-      }
+      multimap.asMap().forEach((key, collectionValue) -> putAll(key, collectionValue));
       return this;
     }
   }
@@ -172,7 +168,7 @@ public final class ImmutableSortedKeyListMultimap<K extends Comparable<K>, V>
     public Set<Entry<K, Collection<V>>> entrySet() {
       ImmutableSet.Builder<Entry<K, Collection<V>>> builder = ImmutableSet.builder();
       for (int i = 0; i < sortedKeys.length; i++) {
-        builder.add(new SimpleImmutableEntry<K, Collection<V>>(sortedKeys[i], values[i]));
+        builder.add(new SimpleImmutableEntry<>(sortedKeys[i], values[i]));
       }
       return builder.build();
     }
@@ -255,11 +251,7 @@ public final class ImmutableSortedKeyListMultimap<K extends Comparable<K>, V>
 
   @Override
   public int size() {
-    int result = 0;
-    for (List<V> list : values) {
-      result += list.size();
-    }
-    return result;
+    return Ints.saturatedCast(Arrays.stream(values).mapToLong(List::size).sum());
   }
 
   @Override
@@ -275,21 +267,13 @@ public final class ImmutableSortedKeyListMultimap<K extends Comparable<K>, V>
 
   @Override
   public boolean containsValue(Object value) {
-    for (List<V> list : values) {
-      if (list.contains(value)) {
-        return true;
-      }
-    }
-    return false;
+    return Arrays.stream(values).anyMatch(list -> list.contains(value));
   }
 
   @Override
   public boolean containsEntry(Object key, Object value) {
     int index = Arrays.binarySearch(sortedKeys, key);
-    if (index >= 0) {
-      return values[index].contains(value);
-    }
-    return false;
+    return index >= 0 && values[index].contains(value);
   }
 
   @Override
@@ -330,7 +314,7 @@ public final class ImmutableSortedKeyListMultimap<K extends Comparable<K>, V>
   @Override
   public List<V> get(K key) {
     int index = Arrays.binarySearch(sortedKeys, key);
-    return index >= 0 ? values[index] : ImmutableList.<V>of();
+    return index >= 0 ? values[index] : ImmutableList.of();
   }
 
   @Override
@@ -353,7 +337,7 @@ public final class ImmutableSortedKeyListMultimap<K extends Comparable<K>, V>
     ImmutableList.Builder<Entry<K, V>> builder = ImmutableList.builder();
     for (int i = 0; i < sortedKeys.length; i++) {
       for (V value : values[i]) {
-        builder.add(new SimpleImmutableEntry<K, V>(sortedKeys[i], value));
+        builder.add(new SimpleImmutableEntry<>(sortedKeys[i], value));
       }
     }
     return builder.build();
diff --git a/src/main/java/com/google/devtools/build/lib/collect/ImmutableSortedKeyMap.java b/src/main/java/com/google/devtools/build/lib/collect/ImmutableSortedKeyMap.java
index 535f4b3552..d3b42c258f 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/ImmutableSortedKeyMap.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/ImmutableSortedKeyMap.java
@@ -13,10 +13,13 @@
 // limitations under the License.
 package com.google.devtools.build.lib.collect;
 
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
+import static java.util.stream.Collectors.joining;
+
 import com.google.common.collect.AbstractIterator;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Streams;
 import com.google.devtools.build.lib.util.Preconditions;
-
 import java.util.AbstractCollection;
 import java.util.AbstractMap.SimpleImmutableEntry;
 import java.util.Arrays;
@@ -26,7 +29,7 @@ import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
-
+import java.util.stream.Stream;
 import javax.annotation.Nullable;
 
 /**
@@ -120,9 +123,7 @@ public final class ImmutableSortedKeyMap<K extends Comparable<K>, V> implements
     }
 
     public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
-      for (Map.Entry<? extends K, ? extends V> entry : map.entrySet()) {
-        put(entry.getKey(), entry.getValue());
-      }
+      map.forEach((key, value) -> put(key, value));
       return this;
     }
   }
@@ -215,15 +216,7 @@ public final class ImmutableSortedKeyMap<K extends Comparable<K>, V> implements
 
   @Override
   public boolean containsValue(@Nullable Object value) {
-    if (value == null) {
-      return false;
-    }
-    for (V v : values) {
-      if (v.equals(value)) {
-        return true;
-      }
-    }
-    return false;
+    return value != null && Arrays.stream(values).anyMatch(v -> v.equals(value));
   }
 
   @Override
@@ -267,34 +260,18 @@ public final class ImmutableSortedKeyMap<K extends Comparable<K>, V> implements
 
   @Override
   public Set<Entry<K, V>> entrySet() {
-    ImmutableSet.Builder<Entry<K, V>> builder = ImmutableSet.builder();
-    for (int i = 0; i < sortedKeys.length; i++) {
-      builder.add(new SimpleImmutableEntry<K, V>(sortedKeys[i], values[i]));
-    }
-    return builder.build();
+    return entryStream().collect(toImmutableSet());
   }
 
   @Override
   public String toString() {
-    StringBuilder result = new StringBuilder();
-    result.append('{');
-    for (int i = 0; i < sortedKeys.length; i++) {
-      if (i != 0) {
-        result.append(", ");
-      }
-      result.append(sortedKeys[i]).append('=').append(values[i]);
-    }
-    result.append('}');
-    return result.toString();
+    return Streams.zip(Arrays.stream(sortedKeys), Arrays.stream(values), (k, v) -> k + "=" + v)
+        .collect(joining(", ", "{", "}"));
   }
 
   @Override
   public int hashCode() {
-    int h = 0;
-    for (Entry<K, V> entry : entrySet()) {
-      h += entry.hashCode();
-    }
-    return h;
+    return entryStream().mapToInt(Entry::hashCode).sum();
   }
 
   @Override
@@ -307,4 +284,8 @@ public final class ImmutableSortedKeyMap<K extends Comparable<K>, V> implements
     }
     return false;
   }
+
+  private Stream<Entry<K, V>> entryStream() {
+    return Streams.zip(Arrays.stream(sortedKeys), Arrays.stream(values), SimpleImmutableEntry::new);
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/collect/IterablesChain.java b/src/main/java/com/google/devtools/build/lib/collect/IterablesChain.java
index 0286798e2a..5fa4f8621e 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/IterablesChain.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/IterablesChain.java
@@ -116,7 +116,7 @@ public final class IterablesChain<T> implements Iterable<T> {
      */
     public IterablesChain<T> build() {
       if (isEmpty()) {
-        return new IterablesChain<>(ImmutableList.<T>of());
+        return new IterablesChain<>(ImmutableList.of());
       }
       Iterable<T> concat = Iterables.concat(ImmutableList.copyOf(iterables));
       return new IterablesChain<>(deduplicate ? new Deduper<>(concat) : concat);
@@ -136,7 +136,7 @@ public final class IterablesChain<T> implements Iterable<T> {
 
     @Override
     public Iterator<T> iterator() {
-      return new DedupingIterator<T>(iterable.iterator());
+      return new DedupingIterator<>(iterable.iterator());
     }
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSet.java b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSet.java
index 74e01eeeca..522d7e9b2e 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSet.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSet.java
@@ -26,7 +26,6 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Objects;
 import java.util.Set;
-import java.util.stream.Stream;
 import javax.annotation.Nullable;
 
 /**
@@ -111,7 +110,7 @@ public final class NestedSet<E> implements Iterable<E> {
             children[n++] = a;
             leaf = false;
           } else {
-            if (!alreadyInserted.contains((E) c) && hoisted.add((E) c)) {
+            if (!alreadyInserted.contains(c) && hoisted.add((E) c)) {
               children[n++] = c;
             }
           }
@@ -231,11 +230,9 @@ public final class NestedSet<E> implements Iterable<E> {
    * different from both standard Java objects and collection-like objects.
    */
   public int shallowHashCode() {
-    if (isSingleton()) {
-      return Objects.hash(order, children);
-    } else {
-      return Objects.hash(order, Arrays.hashCode((Object[]) children));
-    }
+    return isSingleton()
+        ? Objects.hash(order, children)
+        : Objects.hash(order, Arrays.hashCode((Object[]) children));
   }
 
   @Override
@@ -246,20 +243,20 @@ public final class NestedSet<E> implements Iterable<E> {
   // TODO:  this leaves LINK_ORDER backwards
   private static String childrenToString(Object children) {
     if (children instanceof Object[]) {
-      return "{"
-          + Stream.of((Object[]) children).map(Stringer.INSTANCE).collect(joining(", "))
-          + "}";
+      return Arrays.stream((Object[]) children)
+          .map(NestedSet::childrenToString)
+          .collect(joining(", ", "{", "}"));
     } else {
       return children.toString();
     }
   }
 
-  private static enum Stringer implements Function<Object, String> {
+  private enum Stringer implements Function<Object, String> {
     INSTANCE;
     @Override public String apply(Object o) {
       return childrenToString(o);
     }
-  };
+  }
 
   @Override
   public Iterator<E> iterator() {
@@ -275,7 +272,7 @@ public final class NestedSet<E> implements Iterable<E> {
   private ImmutableList<E> expand() {
     // This value is only set in the constructor, so safe to test here with no lock.
     if (memo == LEAF_MEMO) {
-      return ImmutableList.<E>copyOf(new ArraySharingCollection<E>((Object[]) children));
+      return ImmutableList.copyOf(new ArraySharingCollection<>((Object[]) children));
     }
     CompactHashSet<E> members = lockedExpand();
     if (members != null) {
@@ -338,19 +335,17 @@ public final class NestedSet<E> implements Iterable<E> {
    */
   private int walk(CompactHashSet<Object> sets, CompactHashSet<E> members,
                    Object[] children, int pos) {
-    int n = children.length;
-    for (int i = 0; i < n; ++i) {
-      if ((pos>>3) >= memo.length) {
+    for (Object child : children) {
+      if ((pos >> 3) >= memo.length) {
         memo = Arrays.copyOf(memo, memo.length * 2);
       }
-      Object c = children[i];
-      if (c instanceof Object[]) {
-        if (sets.add(c)) {
+      if (child instanceof Object[]) {
+        if (sets.add(child)) {
           int prepos = pos;
           int presize = members.size();
-          pos = walk(sets, members, (Object[]) c, pos + 1);
+          pos = walk(sets, members, (Object[]) child, pos + 1);
           if (presize < members.size()) {
-            memo[prepos>>3] |= 1<<(prepos&7);
+            memo[prepos >> 3] |= 1 << (prepos & 7);
           } else {
             // We didn't find any new nodes, so don't mark this branch as taken.
             // Rewind pos.  The rest of the array is still zeros because no one
@@ -361,8 +356,8 @@ public final class NestedSet<E> implements Iterable<E> {
           ++pos;
         }
       } else {
-        if (members.add((E) c)) {
-          memo[pos>>3] |= 1<<(pos&7);
+        if (members.add((E) child)) {
+          memo[pos >> 3] |= 1 << (pos & 7);
         }
         ++pos;
       }
@@ -376,14 +371,12 @@ public final class NestedSet<E> implements Iterable<E> {
    */
   private static <E> int replay(ImmutableList.Builder<E> output, Object[] children,
                                 byte[] memo, int pos) {
-    int n = children.length;
-    for (int i = 0; i < n; ++i) {
-      Object c = children[i];
-      if ((memo[pos>>3] & (1<<(pos&7))) != 0) {
-        if (c instanceof Object[]) {
-          pos = replay(output, (Object[]) c, memo, pos + 1);
+    for (Object child : children) {
+      if ((memo[pos >> 3] & (1 << (pos & 7))) != 0) {
+        if (child instanceof Object[]) {
+          pos = replay(output, (Object[]) child, memo, pos + 1);
         } else {
-          output.add((E) c);
+          output.add((E) child);
           ++pos;
         }
       } else {
diff --git a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetBuilder.java b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetBuilder.java
index 633572f7fb..0a96139a1b 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetBuilder.java
@@ -148,7 +148,7 @@ public final class NestedSetBuilder<E> {
         return candidate;
       }
     }
-    return new NestedSet<E>(order, items, transitiveSetsCast);
+    return new NestedSet<>(order, items, transitiveSetsCast);
   }
 
   private static final ConcurrentMap<ImmutableList<?>, NestedSet<?>> immutableListCache =
@@ -234,9 +234,7 @@ public final class NestedSetBuilder<E> {
       return stableOrder();
     }
     NestedSetBuilder<E> result = new NestedSetBuilder<>(firstSet.getOrder());
-    for (NestedSet<E> set : sets) {
-      result.addTransitive(set);
-    }
+    sets.forEach(result::addTransitive);
     return result;
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetView.java b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetView.java
index 3defa64d44..b1f778b3fe 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetView.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetView.java
@@ -13,7 +13,10 @@
 // limitations under the License.
 package com.google.devtools.build.lib.collect.nestedset;
 
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
+
 import com.google.common.collect.ImmutableSet;
+import java.util.Arrays;
 import java.util.Set;
 
 /**
@@ -66,15 +69,12 @@ public class NestedSetView<E> {
    */
   public Set<NestedSetView<E>> transitives() {
     if (!(set instanceof Object[])) {
-      return ImmutableSet.<NestedSetView<E>>of();
-    }
-    ImmutableSet.Builder<NestedSetView<E>> transitives = new ImmutableSet.Builder<>();
-    for (Object c : (Object[]) set) {
-      if (c instanceof Object[]) {
-        transitives.add(new NestedSetView<E>(c));
-      }
+      return ImmutableSet.of();
     }
-    return transitives.build();
+    return Arrays.stream((Object[]) set)
+        .filter(c -> c instanceof Object[])
+        .map(c -> new NestedSetView<E>(c))
+        .collect(toImmutableSet());
   }
 
   /**
@@ -86,14 +86,11 @@ public class NestedSetView<E> {
   @SuppressWarnings("unchecked")
   public Set<E> directs() {
     if (!(set instanceof Object[])) {
-      return ImmutableSet.<E>of((E) set);
-    }
-    ImmutableSet.Builder<E> children = new ImmutableSet.Builder<E>();
-    for (Object c : (Object[]) set) {
-      if (!(c instanceof Object[])) {
-        children.add((E) c);
-      }
+      return ImmutableSet.of((E) set);
     }
-    return children.build();
+    return Arrays.stream((Object[]) set)
+        .filter(c -> !(c instanceof Object[]))
+        .map(c -> (E) c)
+        .collect(toImmutableSet());
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetVisitor.java b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetVisitor.java
index 686991cfab..9ced74139b 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetVisitor.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetVisitor.java
@@ -15,7 +15,6 @@ package com.google.devtools.build.lib.collect.nestedset;
 
 import com.google.common.collect.Sets;
 import com.google.devtools.build.lib.util.Preconditions;
-
 import java.util.Set;
 
 /**
@@ -54,7 +53,6 @@ public final class NestedSetVisitor<E> {
    * Transitively visit a nested set.
    *
    * @param nestedSet the nested set to visit transitively.
-   *
    */
   public void visit(NestedSet<E> nestedSet) {
     Preconditions.checkArgument(nestedSet.getOrder() == Order.STABLE_ORDER);
diff --git a/src/main/java/com/google/devtools/build/lib/collect/nestedset/Order.java b/src/main/java/com/google/devtools/build/lib/collect/nestedset/Order.java
index d4ae2d6054..05cc7a1b1a 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/nestedset/Order.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/nestedset/Order.java
@@ -15,7 +15,6 @@ package com.google.devtools.build.lib.collect.nestedset;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
-
 import java.util.HashMap;
 
 /**