Optimize VPath append and prepend

Change-Id: I14b3499b6a31f4598766c7e7ce7fa03905901bcb

1 files changed, 13 insertions, 5 deletions

diff --git a/sched/src/com/android/sched/vfs/VPath.java b/sched/src/com/android/sched/vfs/VPath.java
index 0eeae394..e18c32b7 100644
--- a/sched/src/com/android/sched/vfs/VPath.java
+++ b/sched/src/com/android/sched/vfs/VPath.java
@@ -50,9 +50,11 @@ public final class VPath implements Cloneable {
    */
   public VPath(@Nonnull CharSequence path, char separator) {
     pathFragments = new ArrayList<VPathFragment>(1);
-    VPathFragment pe = new VPathFragment(path, separator);
-    assert pe.isValidPath();
-    pathFragments.add(pe);
+    if (path.length() > 0) {
+      VPathFragment pe = new VPathFragment(path, separator);
+      assert pe.isValidPath();
+      pathFragments.add(pe);
+    }
   }
 
   private VPath(ArrayList<VPathFragment> pathFragments) {
@@ -66,7 +68,8 @@ public final class VPath implements Cloneable {
    * @return the current path
    */
   public VPath prependPath(@Nonnull VPath path) {
-    if (!this.equals(VPath.ROOT)) {
+    assert !path.isRoot();
+    if (!this.isRoot()) {
       pathFragments.add(0,
           new VPathFragment(String.valueOf(INTERNAL_SEPARATOR), INTERNAL_SEPARATOR));
     }
@@ -82,7 +85,8 @@ public final class VPath implements Cloneable {
    * @return the current path
    */
   public VPath appendPath(@Nonnull VPath path) {
-    if (!this.equals(VPath.ROOT)) {
+    assert !path.isRoot();
+    if (!this.isRoot()) {
       pathFragments.add(new VPathFragment(String.valueOf(INTERNAL_SEPARATOR), INTERNAL_SEPARATOR));
     }
     pathFragments.addAll(path.getPathFragments());
@@ -168,6 +172,10 @@ public final class VPath implements Cloneable {
     return getPathAsString(INTERNAL_SEPARATOR);
   }
 
+  public boolean isRoot() {
+    return pathFragments.isEmpty();
+  }
+
   /**
    * A portion of path that should be immutable.
    */