refactor: migrate merge_imports to syntax editor

Co-authored-by: Tarek <tareknaser360@gmail.com>
Signed-off-by: Prajwal S N <prajwalnadig21@gmail.com>

Author: snprajwal

src/tools/rust-analyzer/crates/ide-assists/src/handlers/merge_imports.rs

@@ -1,14 +1,14 @@
 use either::Either;
 use ide_db::imports::{
     insert_use::{ImportGranularity, InsertUseConfig},
-    merge_imports::{MergeBehavior, try_merge_imports, try_merge_trees, try_normalize_use_tree},
+    merge_imports::{MergeBehavior, try_merge_imports, try_merge_trees},
 };
-use itertools::Itertools;
 use syntax::{
     AstNode, SyntaxElement, SyntaxNode,
     algo::neighbor,
-    ast::{self, edit_in_place::Removable},
-    match_ast, ted,
+    ast::{self, syntax_factory::SyntaxFactory},
+    match_ast,
+    syntax_editor::Removable,
 };
 
 use crate::{
@@ -69,49 +69,32 @@ pub(crate) fn merge_imports(acc: &mut Assists, ctx: &AssistContext<'_>) -> Optio
         (selection_range, edits?)
     };
 
+    let parent_node = match ctx.covering_element() {
+        SyntaxElement::Node(n) => n,
+        SyntaxElement::Token(t) => t.parent()?,
+    };
+
     acc.add(AssistId::refactor_rewrite("merge_imports"), "Merge imports", target, |builder| {
-        let edits_mut: Vec<Edit> = edits
-            .into_iter()
-            .map(|it| match it {
-                Remove(Either::Left(it)) => Remove(Either::Left(builder.make_mut(it))),
-                Remove(Either::Right(it)) => Remove(Either::Right(builder.make_mut(it))),
-                Replace(old, new) => Replace(builder.make_syntax_mut(old), new),
-            })
-            .collect();
-        for edit in edits_mut {
+        let make = SyntaxFactory::with_mappings();
+        let mut editor = builder.make_editor(&parent_node);
+
+        for edit in edits {
             match edit {
-                Remove(it) => it.as_ref().either(Removable::remove, Removable::remove),
-                Replace(old, new) => {
-                    ted::replace(old, &new);
-
-                    // If there's a selection and we're replacing a use tree in a tree list,
-                    // normalize the parent use tree if it only contains the merged subtree.
-                    if !ctx.has_empty_selection() {
-                        let normalized_use_tree = ast::UseTree::cast(new)
-                            .as_ref()
-                            .and_then(ast::UseTree::parent_use_tree_list)
-                            .and_then(|use_tree_list| {
-                                if use_tree_list.use_trees().collect_tuple::<(_,)>().is_some() {
-                                    Some(use_tree_list.parent_use_tree())
-                                } else {
-                                    None
-                                }
-                            })
-                            .and_then(|target_tree| {
-                                try_normalize_use_tree(
-                                    &target_tree,
-                                    ctx.config.insert_use.granularity.into(),
-                                )
-                                .map(|top_use_tree_flat| (target_tree, top_use_tree_flat))
-                            });
-                        if let Some((old_tree, new_tree)) = normalized_use_tree {
-                            cov_mark::hit!(replace_parent_with_normalized_use_tree);
-                            ted::replace(old_tree.syntax(), new_tree.syntax());
-                        }
+                Remove(it) => {
+                    let node = it.as_ref();
+                    if let Some(left) = node.left() {
+                        left.remove(&mut editor);
+                    } else if let Some(right) = node.right() {
+                        right.remove(&mut editor);
                     }
                 }
+                Replace(old, new) => {
+                    editor.replace(old, &new);
+                }
             }
         }
+        editor.add_mappings(make.finish_with_mappings());
+        builder.add_file_edits(ctx.vfs_file_id(), editor);
     })
 }
 
@@ -723,11 +706,10 @@ use std::{
         );
 
         cov_mark::check!(merge_with_selected_use_tree_neighbors);
-        cov_mark::check!(replace_parent_with_normalized_use_tree);
         check_assist(
             merge_imports,
             r"use std::$0{fmt::Display, fmt::Debug}$0;",
-            r"use std::fmt::{Debug, Display};",
+            r"use std::{fmt::{Debug, Display}};",
         );
     }