Improve 'introduce variable'

- make it possible to extract a prefix of an expression statement (e.g.
   <|>foo.bar()<|>.baz())
 - don't turn the last expression in a block into a let statement

crates/ra_editor/src/code_actions.rs

@@ -113,7 +113,7 @@ pub fn introduce_variable<'a>(
     let node = find_covering_node(file.syntax(), range);
     let expr = node.ancestors().filter_map(ast::Expr::cast).next()?;
 
-    let anchor_stmt = ahchor_stmt(expr)?;
+    let anchor_stmt = anchor_stmt(expr)?;
     let indent = anchor_stmt.prev_sibling()?;
     if indent.kind() != WHITESPACE {
         return None;
@@ -124,7 +124,12 @@ pub fn introduce_variable<'a>(
 
         buf.push_str("let var_name = ");
         expr.syntax().text().push_to(&mut buf);
-        if expr.syntax().range().start() == anchor_stmt.range().start() {
+        let is_full_stmt = if let Some(expr_stmt) = ast::ExprStmt::cast(anchor_stmt) {
+            Some(expr.syntax()) == expr_stmt.expr().map(|e| e.syntax())
+        } else {
+            false
+        };
+        if is_full_stmt {
             edit.replace(expr.syntax().range(), buf);
         } else {
             buf.push_str(";");
@@ -141,7 +146,7 @@ pub fn introduce_variable<'a>(
 
     /// Statement or last in the block expression, which will follow
     /// the freshly introduced var.
-    fn ahchor_stmt(expr: ast::Expr) -> Option<SyntaxNodeRef> {
+    fn anchor_stmt(expr: ast::Expr) -> Option<SyntaxNodeRef> {
         expr.syntax().ancestors().find(|&node| {
             if ast::Stmt::cast(node).is_some() {
                 return true;
@@ -219,7 +224,7 @@ mod tests {
     }
 
     #[test]
-    fn test_intrdoduce_var_simple() {
+    fn test_introduce_var_simple() {
         check_action_range(
             "
 fn foo() {
@@ -235,7 +240,7 @@ fn foo() {
     }
 
     #[test]
-    fn test_intrdoduce_var_expr_stmt() {
+    fn test_introduce_var_expr_stmt() {
         check_action_range(
             "
 fn foo() {
@@ -250,7 +255,23 @@ fn foo() {
     }
 
     #[test]
-    fn test_intrdoduce_var_last_expr() {
+    fn test_introduce_var_part_of_expr_stmt() {
+        check_action_range(
+            "
+fn foo() {
+    <|>1<|> + 1;
+}",
+            "
+fn foo() {
+    let <|>var_name = 1;
+    var_name + 1;
+}",
+            |file, range| introduce_variable(file, range).map(|f| f()),
+        );
+    }
+
+    #[test]
+    fn test_introduce_var_last_expr() {
         check_action_range(
             "
 fn foo() {
@@ -265,4 +286,20 @@ fn foo() {
         );
     }
 
+    #[test]
+    fn test_introduce_var_last_full_expr() {
+        check_action_range(
+            "
+fn foo() {
+    <|>bar(1 + 1)<|>
+}",
+            "
+fn foo() {
+    let <|>var_name = bar(1 + 1);
+    var_name
+}",
+            |file, range| introduce_variable(file, range).map(|f| f()),
+        );
+    }
+
 }

crates/ra_editor/src/edit.rs

@@ -26,7 +26,7 @@ impl EditBuilder {
     }
     pub fn finish(self) -> Edit {
         let mut atoms = self.atoms;
-        atoms.sort_by_key(|a| a.delete.start());
+        atoms.sort_by_key(|a| (a.delete.start(), a.delete.end()));
         for (a1, a2) in atoms.iter().zip(atoms.iter().skip(1)) {
             assert!(a1.delete.end() <= a2.delete.start())
         }