1 files changed, 49 insertions, 0 deletions

diff --git a/crates/ide_db/src/label.rs b/crates/ide_db/src/label.rs
new file mode 100644
index 000000000..c0e89e72f
--- /dev/null
+++ b/crates/ide_db/src/label.rs
@@ -0,0 +1,49 @@
+//! See `Label`
+use std::fmt;
+
+/// A type to specify UI label, like an entry in the list of assists. Enforces
+/// proper casing:
+///
+///    Frobnicate bar
+///
+/// Note the upper-case first letter and the absence of `.` at the end.
+#[derive(Clone)]
+pub struct Label(String);
+
+impl PartialEq<str> for Label {
+    fn eq(&self, other: &str) -> bool {
+        self.0 == other
+    }
+}
+
+impl PartialEq<&'_ str> for Label {
+    fn eq(&self, other: &&str) -> bool {
+        self == *other
+    }
+}
+
+impl From<Label> for String {
+    fn from(label: Label) -> String {
+        label.0
+    }
+}
+
+impl Label {
+    pub fn new(label: impl Into<String>) -> Label {
+        let label = label.into();
+        assert!(label.starts_with(char::is_uppercase) && !label.ends_with('.'));
+        Label(label)
+    }
+}
+
+impl fmt::Display for Label {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.0, f)
+    }
+}
+
+impl fmt::Debug for Label {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&self.0, f)
+    }
+}