Replace path implementation.

Path and PathFragment have been replaced with String-based implementations. They are pretty similar, but each method is dissimilar enough that I did not feel sharing code was appropriate.

A summary of changes:

PATH
====

* Subsumes LocalPath (deleted, its tests repurposed)
* Use a simple string to back Path
* Path instances are no longer interned; Reference equality will no longer work
* Always normalized (same as before)
* Some operations will now be slower, like instance compares (which were previously just a reference check)
* Multiple identical paths will now consume more memory since they are not interned

PATH FRAGMENT
=============

* Use a simple string to back PathFragment
* No more segment arrays with interned strings
* Always normalized
* Remove isNormalized
* Replace some isNormalizied uses with containsUpLevelReferences() to check if path fragments try to escape their scope
* To check if user input is normalized, supply static methods on PathFragment to validate the string before constructing a PathFragment
* Because PathFragments are always normalized, we have to replace checks for literal "." from PathFragment#getPathString to PathFragment#getSafePathString. The latter returns "." for the empty string.
* The previous implementation supported efficient segment semantics (segment count, iterating over segments). This is now expensive since we do longer have a segment array.

ARTIFACT
========

* Remove Path instance. It is instead dynamically constructed on request. This is necessary to avoid this CL becoming a memory regression.

RELNOTES: None
PiperOrigin-RevId: 185062932

1 files changed, 3 insertions, 4 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/vfs/RootedPath.java b/src/main/java/com/google/devtools/build/lib/vfs/RootedPath.java
index 9182f10c0f..09ab3139a4 100644
--- a/src/main/java/com/google/devtools/build/lib/vfs/RootedPath.java
+++ b/src/main/java/com/google/devtools/build/lib/vfs/RootedPath.java
@@ -30,9 +30,8 @@ import java.util.Objects;
  * <p>Two {@link RootedPath}s are considered equal iff they have equal roots and equal relative
  * paths.
  *
- * <p>TODO(bazel-team): refactor Artifact to use this instead of Root. TODO(bazel-team): use an
- * opaque root representation so as to not expose the absolute path to clients via #asPath or
- * #getRoot.
+ * <p>TODO(bazel-team): use an opaque root representation so as to not expose the absolute path to
+ * clients via #asPath or #getRoot.
  */
 public class RootedPath implements Serializable {
 
@@ -48,7 +47,7 @@ public class RootedPath implements Serializable {
         rootRelativePath,
         root);
     this.root = root;
-    this.rootRelativePath = rootRelativePath.normalize();
+    this.rootRelativePath = rootRelativePath;
     this.path = root.getRelative(this.rootRelativePath);
   }