1 files changed, 11 insertions, 0 deletions
diff --git a/src/document/inspect.rs b/src/document/inspect.rs
index c42de82..f0356de 100644
--- a/src/document/inspect.rs
+++ b/src/document/inspect.rs
@@ -86,6 +86,17 @@ impl Place {
     }
 }
 
+/// Whether any of `changes` does anything at a map key `key`: a cheap look, without
+/// placing anything, for whether they may write the policy (`access::screen`).
+pub(crate) fn touch_key(changes: &[ExpandedChange], key: &str) -> bool {
+    changes.iter().any(|change| {
+        change
+            .operations
+            .iter()
+            .any(|op| matches!(&op.key, Key::Map(name) if name.as_str() == key))
+    })
+}
+
 /// Where a write at `path` in `doc` is, as rules see it (`Inspector`): placed by the
 /// same rule (`Place::child`), so cut after the first list or text on the way, which
 /// what is inside one touches. Where `doc` holds nothing (or a scalar) on the way, the