Add _DRIVE_ROOT, closes #12

pathsjson/impl.py

@@ -196,6 +196,18 @@ def patch_with_user_globals(data, skip_noexist=True):
     return data
 
 
+def inject_special_variables(data, file_path):
+    env = data['__ENV']
+
+    if '_IMPLICIT_ROOT' not in env:
+        env['_IMPLICIT_ROOT'] = os.path.abspath(os.path.dirname(file_path))
+
+    if '_DRIVE_ROOT' not in env:
+        env['_DRIVE_ROOT'] = os.path.abspath(os.sep)
+
+    return data
+
+
 class PathsJSON:
 
     def __init__(self, file_path=None, src_dir=None, target_name=".paths.json",
@@ -218,9 +230,7 @@ def __init__(self, file_path=None, src_dir=None, target_name=".paths.json",
             if enable_env_overrides:
                 data = patch_with_env(data)
 
-            if add_implicit_root and '_IMPLICIT_ROOT' not in data['__ENV']:
-                implicit_root = os.path.abspath(os.path.dirname(file_path))
-                data['__ENV']['_IMPLICIT_ROOT'] = implicit_root
+            inject_special_variables(data, file_path)
 
             if validate:
                 with open(SCHEMA_FILE) as fp:

tests/test_pathsjson.py

@@ -128,6 +128,12 @@ def test_to_path_strs(self):
                     "test_dir": (os.path.join("data", "tests"), [], [])}
         self.assertEqual(path_strs, expected)
 
+    def test_root_paths(self):
+        data = {"__ENV": {}, "user_bin": ["$$_DRIVE_ROOT", "usr", "bin"]}
+        inject_special_variables(data, FIXTURES_DIR)
+        path_strs = to_path_strs(expand(data))
+        self.assertEqual(path_strs['user_bin'][0], '{}/usr/bin')
+
     def test_find_pathsjson_file_asc(self):
         res = find_file_asc(MOCK_LEAF, "test_target")
         self.assertTrue(res.endswith("test_target"))