Add `remove_mut` assist

1 files changed, 32 insertions, 0 deletions

diff --git a/crates/ra_assists/src/handlers/remove_mut.rs b/crates/ra_assists/src/handlers/remove_mut.rs
new file mode 100644
index 000000000..6884830eb
--- /dev/null
+++ b/crates/ra_assists/src/handlers/remove_mut.rs
@@ -0,0 +1,32 @@
+use ra_syntax::{SyntaxKind, TextRange, T};
+
+use crate::{Assist, AssistCtx, AssistId};
+
+// Assist: remove_mut
+//
+// Removes the `mut` keyword.
+//
+// ```
+// impl Walrus {
+//     fn feed(&mut<|> self, amount: u32) {}
+// }
+// ```
+// ->
+// ```
+// impl Walrus {
+//     fn feed(&self, amount: u32) {}
+// }
+// ```
+pub(crate) fn remove_mut(ctx: AssistCtx) -> Option<Assist> {
+    let mut_token = ctx.find_token_at_offset(T![mut])?;
+    let delete_from = mut_token.text_range().start();
+    let delete_to = match mut_token.next_token() {
+        Some(it) if it.kind() == SyntaxKind::WHITESPACE => it.text_range().end(),
+        _ => mut_token.text_range().end(),
+    };
+
+    ctx.add_assist(AssistId("remove_mut"), "Remove `mut` keyword", |edit| {
+        edit.set_cursor(delete_from);
+        edit.delete(TextRange::from_to(delete_from, delete_to));
+    })
+}