7 files changed, 164 insertions, 152 deletions

diff --git a/crates/ide_assists/src/ast_transform.rs b/crates/ide_assists/src/ast_transform.rs
index 4a3ed7783..e5ae718c9 100644
--- a/crates/ide_assists/src/ast_transform.rs
+++ b/crates/ide_assists/src/ast_transform.rs
@@ -3,20 +3,27 @@ use hir::{HirDisplay, PathResolution, SemanticsScope};
 use ide_db::helpers::mod_path_to_ast;
 use rustc_hash::FxHashMap;
 use syntax::{
-    algo::SyntaxRewriter,
     ast::{self, AstNode},
-    SyntaxNode,
+    ted, SyntaxNode,
 };
 
-pub fn apply<'a, N: AstNode>(transformer: &dyn AstTransform<'a>, node: N) -> N {
-    SyntaxRewriter::from_fn(|element| match element {
-        syntax::SyntaxElement::Node(n) => {
-            let replacement = transformer.get_substitution(&n, transformer)?;
-            Some(replacement.into())
+pub fn apply<'a, N: AstNode>(transformer: &dyn AstTransform<'a>, node: &N) {
+    let mut skip_to = None;
+    for event in node.syntax().preorder() {
+        match event {
+            syntax::WalkEvent::Enter(node) if skip_to.is_none() => {
+                skip_to = transformer.get_substitution(&node, transformer).zip(Some(node));
+            }
+            syntax::WalkEvent::Enter(_) => (),
+            syntax::WalkEvent::Leave(node) => match &skip_to {
+                Some((replacement, skip_target)) if *skip_target == node => {
+                    ted::replace(node, replacement.clone_for_update());
+                    skip_to.take();
+                }
+                _ => (),
+            },
         }
-        _ => None,
-    })
-    .rewrite_ast(&node)
+    }
 }
 
 /// `AstTransform` helps with applying bulk transformations to syntax nodes.
@@ -191,11 +198,9 @@ impl<'a> AstTransform<'a> for QualifyPaths<'a> {
                 let found_path = from.find_use_path(self.source_scope.db.upcast(), def)?;
                 let mut path = mod_path_to_ast(&found_path);
 
-                let type_args = p
-                    .segment()
-                    .and_then(|s| s.generic_arg_list())
-                    .map(|arg_list| apply(recur, arg_list));
+                let type_args = p.segment().and_then(|s| s.generic_arg_list());
                 if let Some(type_args) = type_args {
+                    apply(recur, &type_args);
                     let last_segment = path.segment().unwrap();
                     path = path.with_segment(last_segment.with_generic_args(type_args))
                 }
diff --git a/crates/ide_assists/src/handlers/auto_import.rs b/crates/ide_assists/src/handlers/auto_import.rs
index 49aa70f74..a454a2af3 100644
--- a/crates/ide_assists/src/handlers/auto_import.rs
+++ b/crates/ide_assists/src/handlers/auto_import.rs
@@ -93,7 +93,7 @@ pub(crate) fn auto_import(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
 
     let range = ctx.sema.original_range(&syntax_under_caret).range;
     let group_label = group_label(import_assets.import_candidate());
-    let scope = ImportScope::find_insert_use_container(&syntax_under_caret, &ctx.sema)?;
+    let scope = ImportScope::find_insert_use_container_with_macros(&syntax_under_caret, &ctx.sema)?;
     for import in proposed_imports {
         acc.add_group(
             &group_label,
@@ -101,9 +101,11 @@ pub(crate) fn auto_import(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
             format!("Import `{}`", import.import_path),
             range,
             |builder| {
-                let rewriter =
-                    insert_use(&scope, mod_path_to_ast(&import.import_path), ctx.config.insert_use);
-                builder.rewrite(rewriter);
+                let scope = match scope.clone() {
+                    ImportScope::File(it) => ImportScope::File(builder.make_ast_mut(it)),
+                    ImportScope::Module(it) => ImportScope::Module(builder.make_ast_mut(it)),
+                };
+                insert_use(&scope, mod_path_to_ast(&import.import_path), ctx.config.insert_use);
             },
         );
     }
diff --git a/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs b/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs
index a8d6355bd..66f274fa7 100644
--- a/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs
+++ b/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs
@@ -5,7 +5,7 @@ use hir::{Module, ModuleDef, Name, Variant};
 use ide_db::{
     defs::Definition,
     helpers::{
-        insert_use::{insert_use, ImportScope},
+        insert_use::{insert_use, ImportScope, InsertUseConfig},
         mod_path_to_ast,
     },
     search::FileReference,
@@ -13,9 +13,9 @@ use ide_db::{
 };
 use rustc_hash::FxHashSet;
 use syntax::{
-    algo::{find_node_at_offset, SyntaxRewriter},
-    ast::{self, edit::IndentLevel, make, AstNode, NameOwner, VisibilityOwner},
-    SourceFile, SyntaxElement, SyntaxNode, T,
+    algo::find_node_at_offset,
+    ast::{self, make, AstNode, NameOwner, VisibilityOwner},
+    ted, SyntaxNode, T,
 };
 
 use crate::{AssistContext, AssistId, AssistKind, Assists};
@@ -62,40 +62,50 @@ pub(crate) fn extract_struct_from_enum_variant(
             let mut visited_modules_set = FxHashSet::default();
             let current_module = enum_hir.module(ctx.db());
             visited_modules_set.insert(current_module);
-            let mut def_rewriter = None;
+            // record file references of the file the def resides in, we only want to swap to the edited file in the builder once
+            let mut def_file_references = None;
             for (file_id, references) in usages {
-                let mut rewriter = SyntaxRewriter::default();
-                let source_file = ctx.sema.parse(file_id);
-                for reference in references {
-                    update_reference(
-                        ctx,
-                        &mut rewriter,
-                        reference,
-                        &source_file,
-                        &enum_module_def,
-                        &variant_hir_name,
-                        &mut visited_modules_set,
-                    );
-                }
                 if file_id == ctx.frange.file_id {
-                    def_rewriter = Some(rewriter);
+                    def_file_references = Some(references);
                     continue;
                 }
                 builder.edit_file(file_id);
-                builder.rewrite(rewriter);
+                let source_file = builder.make_ast_mut(ctx.sema.parse(file_id));
+                let processed = process_references(
+                    ctx,
+                    &mut visited_modules_set,
+                    source_file.syntax(),
+                    &enum_module_def,
+                    &variant_hir_name,
+                    references,
+                );
+                processed.into_iter().for_each(|(path, node, import)| {
+                    apply_references(ctx.config.insert_use, path, node, import)
+                });
             }
-            let mut rewriter = def_rewriter.unwrap_or_default();
-            update_variant(&mut rewriter, &variant);
-            extract_struct_def(
-                &mut rewriter,
-                &enum_ast,
-                variant_name.clone(),
-                &field_list,
-                &variant.parent_enum().syntax().clone().into(),
-                enum_ast.visibility(),
-            );
             builder.edit_file(ctx.frange.file_id);
-            builder.rewrite(rewriter);
+            let source_file = builder.make_ast_mut(ctx.sema.parse(ctx.frange.file_id));
+            let variant = builder.make_ast_mut(variant.clone());
+            if let Some(references) = def_file_references {
+                let processed = process_references(
+                    ctx,
+                    &mut visited_modules_set,
+                    source_file.syntax(),
+                    &enum_module_def,
+                    &variant_hir_name,
+                    references,
+                );
+                processed.into_iter().for_each(|(path, node, import)| {
+                    apply_references(ctx.config.insert_use, path, node, import)
+                });
+            }
+
+            let def = create_struct_def(variant_name.clone(), &field_list, enum_ast.visibility());
+            let start_offset = &variant.parent_enum().syntax().clone();
+            ted::insert_raw(ted::Position::before(start_offset), def.syntax());
+            ted::insert_raw(ted::Position::before(start_offset), &make::tokens::blank_line());
+
+            update_variant(&variant);
         },
     )
 }
@@ -136,34 +146,11 @@ fn existing_definition(db: &RootDatabase, variant_name: &ast::Name, variant: &Va
         .any(|(name, _)| name.to_string() == variant_name.to_string())
 }
 
-fn insert_import(
-    ctx: &AssistContext,
-    rewriter: &mut SyntaxRewriter,
-    scope_node: &SyntaxNode,
-    module: &Module,
-    enum_module_def: &ModuleDef,
-    variant_hir_name: &Name,
-) -> Option<()> {
-    let db = ctx.db();
-    let mod_path =
-        module.find_use_path_prefixed(db, *enum_module_def, ctx.config.insert_use.prefix_kind);
-    if let Some(mut mod_path) = mod_path {
-        mod_path.pop_segment();
-        mod_path.push_segment(variant_hir_name.clone());
-        let scope = ImportScope::find_insert_use_container(scope_node, &ctx.sema)?;
-        *rewriter += insert_use(&scope, mod_path_to_ast(&mod_path), ctx.config.insert_use);
-    }
-    Some(())
-}
-
-fn extract_struct_def(
-    rewriter: &mut SyntaxRewriter,
-    enum_: &ast::Enum,
+fn create_struct_def(
     variant_name: ast::Name,
     field_list: &Either<ast::RecordFieldList, ast::TupleFieldList>,
-    start_offset: &SyntaxElement,
     visibility: Option<ast::Visibility>,
-) -> Option<()> {
+) -> ast::Struct {
     let pub_vis = Some(make::visibility_pub());
     let field_list = match field_list {
         Either::Left(field_list) => {
@@ -180,65 +167,90 @@ fn extract_struct_def(
         .into(),
     };
 
-    rewriter.insert_before(
-        start_offset,
-        make::struct_(visibility, variant_name, None, field_list).syntax(),
-    );
-    rewriter.insert_before(start_offset, &make::tokens::blank_line());
-
-    if let indent_level @ 1..=usize::MAX = IndentLevel::from_node(enum_.syntax()).0 as usize {
-        rewriter
-            .insert_before(start_offset, &make::tokens::whitespace(&" ".repeat(4 * indent_level)));
-    }
-    Some(())
+    make::struct_(visibility, variant_name, None, field_list).clone_for_update()
 }
 
-fn update_variant(rewriter: &mut SyntaxRewriter, variant: &ast::Variant) -> Option<()> {
+fn update_variant(variant: &ast::Variant) -> Option<()> {
     let name = variant.name()?;
     let tuple_field = make::tuple_field(None, make::ty(&name.text()));
     let replacement = make::variant(
         name,
         Some(ast::FieldList::TupleFieldList(make::tuple_field_list(iter::once(tuple_field)))),
-    );
-    rewriter.replace(variant.syntax(), replacement.syntax());
+    )
+    .clone_for_update();
+    ted::replace(variant.syntax(), replacement.syntax());
     Some(())
 }
 
-fn update_reference(
+fn apply_references(
+    insert_use_cfg: InsertUseConfig,
+    segment: ast::PathSegment,
+    node: SyntaxNode,
+    import: Option<(ImportScope, hir::ModPath)>,
+) {
+    if let Some((scope, path)) = import {
+        insert_use(&scope, mod_path_to_ast(&path), insert_use_cfg);
+    }
+    ted::insert_raw(
+        ted::Position::before(segment.syntax()),
+        make::path_from_text(&format!("{}", segment)).clone_for_update().syntax(),
+    );
+    ted::insert_raw(ted::Position::before(segment.syntax()), make::token(T!['(']));
+    ted::insert_raw(ted::Position::after(&node), make::token(T![')']));
+}
+
+fn process_references(
     ctx: &AssistContext,
-    rewriter: &mut SyntaxRewriter,
-    reference: FileReference,
-    source_file: &SourceFile,
+    visited_modules: &mut FxHashSet<Module>,
+    source_file: &SyntaxNode,
     enum_module_def: &ModuleDef,
     variant_hir_name: &Name,
-    visited_modules_set: &mut FxHashSet<Module>,
-) -> Option<()> {
+    refs: Vec<FileReference>,
+) -> Vec<(ast::PathSegment, SyntaxNode, Option<(ImportScope, hir::ModPath)>)> {
+    // we have to recollect here eagerly as we are about to edit the tree we need to calculate the changes
+    // and corresponding nodes up front
+    refs.into_iter()
+        .flat_map(|reference| {
+            let (segment, scope_node, module) =
+                reference_to_node(&ctx.sema, source_file, reference)?;
+            if !visited_modules.contains(&module) {
+                let mod_path = module.find_use_path_prefixed(
+                    ctx.sema.db,
+                    *enum_module_def,
+                    ctx.config.insert_use.prefix_kind,
+                );
+                if let Some(mut mod_path) = mod_path {
+                    mod_path.pop_segment();
+                    mod_path.push_segment(variant_hir_name.clone());
+                    let scope = ImportScope::find_insert_use_container(&scope_node)?;
+                    visited_modules.insert(module);
+                    return Some((segment, scope_node, Some((scope, mod_path))));
+                }
+            }
+            Some((segment, scope_node, None))
+        })
+        .collect()
+}
+
+fn reference_to_node(
+    sema: &hir::Semantics<RootDatabase>,
+    source_file: &SyntaxNode,
+    reference: FileReference,
+) -> Option<(ast::PathSegment, SyntaxNode, hir::Module)> {
     let offset = reference.range.start();
-    let (segment, expr) = if let Some(path_expr) =
-        find_node_at_offset::<ast::PathExpr>(source_file.syntax(), offset)
-    {
+    if let Some(path_expr) = find_node_at_offset::<ast::PathExpr>(source_file, offset) {
         // tuple variant
-        (path_expr.path()?.segment()?, path_expr.syntax().parent()?)
-    } else if let Some(record_expr) =
-        find_node_at_offset::<ast::RecordExpr>(source_file.syntax(), offset)
-    {
+        Some((path_expr.path()?.segment()?, path_expr.syntax().parent()?))
+    } else if let Some(record_expr) = find_node_at_offset::<ast::RecordExpr>(source_file, offset) {
         // record variant
-        (record_expr.path()?.segment()?, record_expr.syntax().clone())
+        Some((record_expr.path()?.segment()?, record_expr.syntax().clone()))
     } else {
-        return None;
-    };
-
-    let module = ctx.sema.scope(&expr).module()?;
-    if !visited_modules_set.contains(&module) {
-        if insert_import(ctx, rewriter, &expr, &module, enum_module_def, variant_hir_name).is_some()
-        {
-            visited_modules_set.insert(module);
-        }
+        None
     }
-    rewriter.insert_after(segment.syntax(), &make::token(T!['(']));
-    rewriter.insert_after(segment.syntax(), segment.syntax());
-    rewriter.insert_after(&expr, &make::token(T![')']));
-    Some(())
+    .and_then(|(segment, expr)| {
+        let module = sema.scope(&expr).module()?;
+        Some((segment, expr, module))
+    })
 }
 
 #[cfg(test)]
@@ -345,7 +357,7 @@ mod my_mod {
 
         pub struct MyField(pub u8, pub u8);
 
-        pub enum MyEnum {
+pub enum MyEnum {
             MyField(MyField),
         }
     }
diff --git a/crates/ide_assists/src/handlers/reorder_fields.rs b/crates/ide_assists/src/handlers/reorder_fields.rs
index 1a95135ca..e90bbdbcf 100644
--- a/crates/ide_assists/src/handlers/reorder_fields.rs
+++ b/crates/ide_assists/src/handlers/reorder_fields.rs
@@ -83,11 +83,9 @@ fn replace<T: AstNode + PartialEq>(
     fields: impl Iterator<Item = T>,
     sorted_fields: impl IntoIterator<Item = T>,
 ) {
-    fields.zip(sorted_fields).filter(|(field, sorted)| field != sorted).for_each(
-        |(field, sorted_field)| {
-            ted::replace(field.syntax(), sorted_field.syntax().clone_for_update());
-        },
-    );
+    fields.zip(sorted_fields).for_each(|(field, sorted_field)| {
+        ted::replace(field.syntax(), sorted_field.syntax().clone_for_update())
+    });
 }
 
 fn compute_fields_ranks(path: &ast::Path, ctx: &AssistContext) -> Option<FxHashMap<String, usize>> {
diff --git a/crates/ide_assists/src/handlers/reorder_impl.rs b/crates/ide_assists/src/handlers/reorder_impl.rs
index f976e73ad..72d889248 100644
--- a/crates/ide_assists/src/handlers/reorder_impl.rs
+++ b/crates/ide_assists/src/handlers/reorder_impl.rs
@@ -4,9 +4,8 @@ use rustc_hash::FxHashMap;
 use hir::{PathResolution, Semantics};
 use ide_db::RootDatabase;
 use syntax::{
-    algo,
     ast::{self, NameOwner},
-    AstNode,
+    ted, AstNode,
 };
 
 use crate::{AssistContext, AssistId, AssistKind, Assists};
@@ -75,13 +74,16 @@ pub(crate) fn reorder_impl(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
     }
 
     let target = items.syntax().text_range();
-    acc.add(AssistId("reorder_impl", AssistKind::RefactorRewrite), "Sort methods", target, |edit| {
-        let mut rewriter = algo::SyntaxRewriter::default();
-        for (old, new) in methods.iter().zip(&sorted) {
-            rewriter.replace(old.syntax(), new.syntax());
-        }
-        edit.rewrite(rewriter);
-    })
+    acc.add(
+        AssistId("reorder_impl", AssistKind::RefactorRewrite),
+        "Sort methods",
+        target,
+        |builder| {
+            methods.into_iter().zip(sorted).for_each(|(old, new)| {
+                ted::replace(builder.make_ast_mut(old).syntax(), new.clone_for_update().syntax())
+            });
+        },
+    )
 }
 
 fn compute_method_ranks(path: &ast::Path, ctx: &AssistContext) -> Option<FxHashMap<String, usize>> {
diff --git a/crates/ide_assists/src/handlers/replace_qualified_name_with_use.rs b/crates/ide_assists/src/handlers/replace_qualified_name_with_use.rs
index 36d2e0331..99ba79860 100644
--- a/crates/ide_assists/src/handlers/replace_qualified_name_with_use.rs
+++ b/crates/ide_assists/src/handlers/replace_qualified_name_with_use.rs
@@ -1,5 +1,5 @@
 use ide_db::helpers::insert_use::{insert_use, ImportScope};
-use syntax::{algo::SyntaxRewriter, ast, match_ast, AstNode, SyntaxNode};
+use syntax::{ast, match_ast, ted, AstNode, SyntaxNode};
 
 use crate::{AssistContext, AssistId, AssistKind, Assists};
 
@@ -31,7 +31,7 @@ pub(crate) fn replace_qualified_name_with_use(
     }
 
     let target = path.syntax().text_range();
-    let scope = ImportScope::find_insert_use_container(path.syntax(), &ctx.sema)?;
+    let scope = ImportScope::find_insert_use_container_with_macros(path.syntax(), &ctx.sema)?;
     let syntax = scope.as_syntax_node();
     acc.add(
         AssistId("replace_qualified_name_with_use", AssistKind::RefactorRewrite),
@@ -40,18 +40,17 @@ pub(crate) fn replace_qualified_name_with_use(
         |builder| {
             // Now that we've brought the name into scope, re-qualify all paths that could be
             // affected (that is, all paths inside the node we added the `use` to).
-            let mut rewriter = SyntaxRewriter::default();
-            shorten_paths(&mut rewriter, syntax.clone(), &path);
+            let syntax = builder.make_mut(syntax.clone());
             if let Some(ref import_scope) = ImportScope::from(syntax.clone()) {
-                rewriter += insert_use(import_scope, path, ctx.config.insert_use);
-                builder.rewrite(rewriter);
+                shorten_paths(&syntax, &path.clone_for_update());
+                insert_use(import_scope, path, ctx.config.insert_use);
             }
         },
     )
 }
 
 /// Adds replacements to `re` that shorten `path` in all descendants of `node`.
-fn shorten_paths(rewriter: &mut SyntaxRewriter<'static>, node: SyntaxNode, path: &ast::Path) {
+fn shorten_paths(node: &SyntaxNode, path: &ast::Path) {
     for child in node.children() {
         match_ast! {
             match child {
@@ -60,34 +59,26 @@ fn shorten_paths(rewriter: &mut SyntaxRewriter<'static>, node: SyntaxNode, path:
                 ast::Use(_it) => continue,
                 // Don't descend into submodules, they don't have the same `use` items in scope.
                 ast::Module(_it) => continue,
-
-                ast::Path(p) => {
-                    match maybe_replace_path(rewriter, p.clone(), path.clone()) {
-                        Some(()) => {},
-                        None => shorten_paths(rewriter, p.syntax().clone(), path),
-                    }
+                ast::Path(p) => if maybe_replace_path(p.clone(), path.clone()).is_none() {
+                    shorten_paths(p.syntax(), path);
                 },
-                _ => shorten_paths(rewriter, child, path),
+                _ => shorten_paths(&child, path),
             }
         }
     }
 }
 
-fn maybe_replace_path(
-    rewriter: &mut SyntaxRewriter<'static>,
-    path: ast::Path,
-    target: ast::Path,
-) -> Option<()> {
+fn maybe_replace_path(path: ast::Path, target: ast::Path) -> Option<()> {
     if !path_eq(path.clone(), target) {
         return None;
     }
 
     // Shorten `path`, leaving only its last segment.
     if let Some(parent) = path.qualifier() {
-        rewriter.delete(parent.syntax());
+        ted::remove(parent.syntax());
     }
     if let Some(double_colon) = path.coloncolon_token() {
-        rewriter.delete(&double_colon);
+        ted::remove(&double_colon);
     }
 
     Some(())
@@ -150,6 +141,7 @@ Debug
     ",
         );
     }
+
     #[test]
     fn test_replace_add_use_no_anchor_with_item_below() {
         check_assist(
diff --git a/crates/ide_assists/src/utils.rs b/crates/ide_assists/src/utils.rs
index d67524937..5a90ad715 100644
--- a/crates/ide_assists/src/utils.rs
+++ b/crates/ide_assists/src/utils.rs
@@ -140,7 +140,8 @@ pub fn add_trait_assoc_items_to_impl(
 
     let items = items
         .into_iter()
-        .map(|it| ast_transform::apply(&*ast_transform, it))
+        .map(|it| it.clone_for_update())
+        .inspect(|it| ast_transform::apply(&*ast_transform, it))
         .map(|it| match it {
             ast::AssocItem::Fn(def) => ast::AssocItem::Fn(add_body(def)),
             ast::AssocItem::TypeAlias(def) => ast::AssocItem::TypeAlias(def.remove_bounds()),