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

5 files changed, 38 insertions, 53 deletions

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;
 
 /**