Add a helper function to DiffusionPathIDQuery

Summary:
Just breaking D960 into some smaller parts, this is a standalone method used in
Mercurial parsing.

(There's a bad version of this function in the SVN stuff but I'll get rid of it
the next time I'm in there.)

Test Plan: See D960.

Reviewers: Makinde, jungejason, nh, tuomaspelkonen, aran

Reviewed By: Makinde

CC: aran, Makinde

Differential Revision: 965

src/applications/diffusion/query/pathid/base/DiffusionPathIDQuery.php

@@ -16,6 +16,9 @@
  * limitations under the License.
  */
 
+/**
+ * @task pathutil Path Utilities
+ */
 final class DiffusionPathIDQuery {
 
   public function __construct(array $paths) {
@@ -49,13 +52,55 @@ final class DiffusionPathIDQuery {
     return $result;
   }
 
+
+  /**
+   * Convert a path to the canonical, absolute representation used by Diffusion.
+   *
+   * @param string Some repository path.
+   * @return string Canonicalized Diffusion path.
+   * @task pathutil
+   */
   public static function normalizePath($path) {
+
+    // Normalize to single slashes, e.g. "///" => "/".
+    $path = preg_replace('@[/]{2,}@', '/', $path);
+
     return '/'.trim($path, '/');
   }
 
+
+  /**
+   * Return the canonical parent directory for a path. Note, returns "/" when
+   * passed "/".
+   *
+   * @param string Some repository path.
+   * @return string That path's canonical parent directory.
+   * @task pathutil
+   */
   public static function getParentPath($path) {
     $path = self::normalizePath($path);
     return dirname($path);
   }
 
+
+  /**
+   * Generate a list of parents for a repository path. The path itself is
+   * included.
+   *
+   * @param string Some repository path.
+   * @return list List of canonical paths between the path and the root.
+   * @task pathutil
+   */
+  public static function expandPathToRoot($path) {
+    $path = self::normalizePath($path);
+    $parents = array($path);
+    $parts = explode('/', trim($path, '/'));
+    while (count($parts) >= 1) {
+      if (array_pop($parts)) {
+        $parents[] = '/'.implode('/', $parts);
+      }
+    }
+    return $parents;
+  }
+
 }

src/applications/diffusion/query/pathid/base/__tests__/DiffusionPathQueryTestCase.php

@@ -31,6 +31,28 @@ final class DiffusionPathQueryTestCase extends PhabricatorTestCase {
       '/a',
       DiffusionPathIDQuery::getParentPath('/a/b'),
       'Parent of /a/b');
+    $this->assertEqual(
+      '/a',
+      DiffusionPathIDQuery::getParentPath('/a///b'),
+      'Parent of /a///b');
+  }
+
+  public function testExpandEdgeCases() {
+    $this->assertEqual(
+      array('/'),
+      DiffusionPathIDQuery::expandPathToRoot('/'));
+    $this->assertEqual(
+      array('/'),
+      DiffusionPathIDQuery::expandPathToRoot('//'));
+    $this->assertEqual(
+      array('/a/b', '/a', '/'),
+      DiffusionPathIDQuery::expandPathToRoot('/a/b'));
+    $this->assertEqual(
+      array('/a/b', '/a', '/'),
+      DiffusionPathIDQuery::expandPathToRoot('/a//b'));
+    $this->assertEqual(
+      array('/a/b', '/a', '/'),
+      DiffusionPathIDQuery::expandPathToRoot('a/b'));
   }
 
 }