1 files changed, 61 insertions, 0 deletions

diff --git a/crates/ra_assists/src/assists/split_import.rs b/crates/ra_assists/src/assists/split_import.rs
new file mode 100644
index 000000000..2c1edddb9
--- /dev/null
+++ b/crates/ra_assists/src/assists/split_import.rs
@@ -0,0 +1,61 @@
+use std::iter::successors;
+
+use hir::db::HirDatabase;
+use ra_syntax::{ast, AstNode, TextUnit, T};
+
+use crate::{Assist, AssistCtx, AssistId};
+
+pub(crate) fn split_import(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let colon_colon = ctx.token_at_offset().find(|leaf| leaf.kind() == T![::])?;
+    let path = ast::Path::cast(colon_colon.parent())?;
+    let top_path = successors(Some(path), |it| it.parent_path()).last()?;
+
+    let use_tree = top_path.syntax().ancestors().find_map(ast::UseTree::cast);
+    if use_tree.is_none() {
+        return None;
+    }
+
+    let l_curly = colon_colon.text_range().end();
+    let r_curly = match top_path.syntax().parent().and_then(ast::UseTree::cast) {
+        Some(tree) => tree.syntax().text_range().end(),
+        None => top_path.syntax().text_range().end(),
+    };
+
+    ctx.add_action(AssistId("split_import"), "split import", |edit| {
+        edit.target(colon_colon.text_range());
+        edit.insert(l_curly, "{");
+        edit.insert(r_curly, "}");
+        edit.set_cursor(l_curly + TextUnit::of_str("{"));
+    });
+
+    ctx.build()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::helpers::{check_assist, check_assist_target};
+
+    #[test]
+    fn test_split_import() {
+        check_assist(
+            split_import,
+            "use crate::<|>db::RootDatabase;",
+            "use crate::{<|>db::RootDatabase};",
+        )
+    }
+
+    #[test]
+    fn split_import_works_with_trees() {
+        check_assist(
+            split_import,
+            "use algo:<|>:visitor::{Visitor, visit}",
+            "use algo::{<|>visitor::{Visitor, visit}}",
+        )
+    }
+
+    #[test]
+    fn split_import_target() {
+        check_assist_target(split_import, "use algo::<|>visitor::{Visitor, visit}", "::");
+    }
+}