hierarchy-extract-tree now returns nil when item is not in hierarchy

DamienCassou · Apr 14, 2017 · 1de3a48 · 1de3a48
1 parent bc455d5
commit 1de3a48
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Showing 2 changed files with 13 additions and 7 deletions.
diff --git a/hierarchy.el b/hierarchy.el
@@ -168,13 +168,15 @@ default, SORTFN is `string-lessp'."
 
 (defun hierarchy-extract-tree (hierarchy item)
   "Return a copy of HIERARCHY with ITEM's descendants and parents."
-  (let ((tree (hierarchy-new)))
-    (hierarchy-add-tree tree item
-                        (lambda (each) (hierarchy-parent hierarchy each))
-                        (lambda (each) (when (or (equal each item)
-                                            (hierarchy-descendant-p hierarchy each item))
-                                    (hierarchy-children hierarchy each))))
-    tree))
+  (if (not (hierarchy-has-item hierarchy item))
+      nil
+    (let ((tree (hierarchy-new)))
+      (hierarchy-add-tree tree item
+                          (lambda (each) (hierarchy-parent hierarchy each))
+                          (lambda (each) (when (or (equal each item)
+                                              (hierarchy-descendant-p hierarchy each item))
+                                      (hierarchy-children hierarchy each))))
+     tree)))
 
 
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diff --git a/test/hierarchy-test.el b/test/hierarchy-test.el
@@ -308,6 +308,10 @@
     (should (equal (hierarchy-children birds 'animal) '(bird)))
     (should (equal (hierarchy-children birds 'bird) '(dove pigeon)))))
 
+(ert-deftest hierarchy-extract-tree-nil-if-not-in-hierarchy ()
+  (let* ((animals (test-helper-animals)))
+    (should-not (hierarchy-extract-tree animals 'foobar))))
+
 (ert-deftest hierarchy-labelfn-indent-no-indent-if-0 ()
   (let* ((labelfn-base (lambda (_item _indent) (insert "foo")))
          (labelfn (hierarchy-labelfn-indent labelfn-base)))