20 files changed, 271 insertions, 227 deletions

diff --git a/crates/ra_assists/src/assist_ctx.rs b/crates/ra_assists/src/assist_ctx.rs
index 82f61bc8f..83dd270c6 100644
--- a/crates/ra_assists/src/assist_ctx.rs
+++ b/crates/ra_assists/src/assist_ctx.rs
@@ -4,14 +4,13 @@ use ra_db::FileRange;
 use ra_fmt::{leading_indent, reindent};
 use ra_ide_db::RootDatabase;
 use ra_syntax::{
-    algo::{self, find_covering_element, find_node_at_offset},
+    algo::{self, find_covering_element, find_node_at_offset, SyntaxRewriter},
     AstNode, SourceFile, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken, TextRange, TextSize,
     TokenAtOffset,
 };
 use ra_text_edit::TextEditBuilder;
 
 use crate::{AssistAction, AssistFile, AssistId, AssistLabel, GroupLabel, ResolvedAssist};
-use algo::SyntaxRewriter;
 
 #[derive(Clone, Debug)]
 pub(crate) struct Assist(pub(crate) Vec<AssistInfo>);
@@ -42,8 +41,6 @@ impl AssistInfo {
     }
 }
 
-pub(crate) type AssistHandler = fn(AssistCtx) -> Option<Assist>;
-
 /// `AssistCtx` allows to apply an assist or check if it could be applied.
 ///
 /// Assists use a somewhat over-engineered approach, given the current needs. The
diff --git a/crates/ra_assists/src/doc_tests.rs b/crates/ra_assists/src/doc_tests.rs
index c0f9bc1fb..f627f31dc 100644
--- a/crates/ra_assists/src/doc_tests.rs
+++ b/crates/ra_assists/src/doc_tests.rs
@@ -30,6 +30,10 @@ fn check(assist_id: &str, before: &str, after: &str) {
             )
         });
 
-    let actual = assist.action.edit.apply(&before);
+    let actual = {
+        let mut actual = before.clone();
+        assist.action.edit.apply(&mut actual);
+        actual
+    };
     assert_eq_text!(after, &actual);
 }
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index 5cec10088..0f94f5ee8 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -23,7 +23,7 @@ use ra_ide_db::RootDatabase;
 use ra_syntax::{TextRange, TextSize};
 use ra_text_edit::TextEdit;
 
-pub(crate) use crate::assist_ctx::{Assist, AssistCtx, AssistHandler};
+pub(crate) use crate::assist_ctx::{Assist, AssistCtx};
 
 /// Unique identifier of the assist, should not be shown to the user
 /// directly.
@@ -109,7 +109,9 @@ pub fn resolved_assists(db: &RootDatabase, range: FileRange) -> Vec<ResolvedAssi
 }
 
 mod handlers {
-    use crate::AssistHandler;
+    use crate::{Assist, AssistCtx};
+
+    pub(crate) type Handler = fn(AssistCtx) -> Option<Assist>;
 
     mod add_custom_impl;
     mod add_derive;
@@ -145,12 +147,13 @@ mod handlers {
     mod reorder_fields;
     mod unwrap_block;
 
-    pub(crate) fn all() -> &'static [AssistHandler] {
+    pub(crate) fn all() -> &'static [Handler] {
         &[
             // These are alphabetic for the foolish consistency
             add_custom_impl::add_custom_impl,
             add_derive::add_derive,
             add_explicit_type::add_explicit_type,
+            add_from_impl_for_enum::add_from_impl_for_enum,
             add_function::add_function,
             add_impl::add_impl,
             add_new::add_new,
@@ -176,17 +179,18 @@ mod handlers {
             raw_string::remove_hash,
             remove_dbg::remove_dbg,
             remove_mut::remove_mut,
+            reorder_fields::reorder_fields,
             replace_if_let_with_match::replace_if_let_with_match,
             replace_let_with_if_let::replace_let_with_if_let,
             replace_qualified_name_with_use::replace_qualified_name_with_use,
             replace_unwrap_with_match::replace_unwrap_with_match,
             split_import::split_import,
-            add_from_impl_for_enum::add_from_impl_for_enum,
             unwrap_block::unwrap_block,
             // These are manually sorted for better priorities
             add_missing_impl_members::add_missing_impl_members,
             add_missing_impl_members::add_missing_default_members,
-            reorder_fields::reorder_fields,
+            // Are you sure you want to add new assist here, and not to the
+            // sorted list above?
         ]
     }
 }
@@ -195,12 +199,12 @@ mod handlers {
 mod helpers {
     use std::sync::Arc;
 
+    use hir::Semantics;
     use ra_db::{fixture::WithFixture, FileId, FileRange, SourceDatabaseExt};
     use ra_ide_db::{symbol_index::SymbolsDatabase, RootDatabase};
     use test_utils::{add_cursor, assert_eq_text, extract_range_or_offset, RangeOrOffset};
 
-    use crate::{AssistCtx, AssistFile, AssistHandler};
-    use hir::Semantics;
+    use crate::{handlers::Handler, AssistCtx, AssistFile};
 
     pub(crate) fn with_single_file(text: &str) -> (RootDatabase, FileId) {
         let (mut db, file_id) = RootDatabase::with_single_file(text);
@@ -210,22 +214,18 @@ mod helpers {
         (db, file_id)
     }
 
-    pub(crate) fn check_assist(
-        assist: AssistHandler,
-        ra_fixture_before: &str,
-        ra_fixture_after: &str,
-    ) {
+    pub(crate) fn check_assist(assist: Handler, ra_fixture_before: &str, ra_fixture_after: &str) {
         check(assist, ra_fixture_before, ExpectedResult::After(ra_fixture_after));
     }
 
     // FIXME: instead of having a separate function here, maybe use
     // `extract_ranges` and mark the target as `<target> </target>` in the
     // fixuture?
-    pub(crate) fn check_assist_target(assist: AssistHandler, ra_fixture: &str, target: &str) {
+    pub(crate) fn check_assist_target(assist: Handler, ra_fixture: &str, target: &str) {
         check(assist, ra_fixture, ExpectedResult::Target(target));
     }
 
-    pub(crate) fn check_assist_not_applicable(assist: AssistHandler, ra_fixture: &str) {
+    pub(crate) fn check_assist_not_applicable(assist: Handler, ra_fixture: &str) {
         check(assist, ra_fixture, ExpectedResult::NotApplicable);
     }
 
@@ -235,7 +235,7 @@ mod helpers {
         Target(&'a str),
     }
 
-    fn check(assist: AssistHandler, before: &str, expected: ExpectedResult) {
+    fn check(assist: Handler, before: &str, expected: ExpectedResult) {
         let (text_without_caret, file_with_caret_id, range_or_offset, db) =
             if before.contains("//-") {
                 let (mut db, position) = RootDatabase::with_position(before);
@@ -261,13 +261,13 @@ mod helpers {
             (Some(assist), ExpectedResult::After(after)) => {
                 let action = assist.0[0].action.clone().unwrap();
 
-                let assisted_file_text = if let AssistFile::TargetFile(file_id) = action.file {
+                let mut actual = if let AssistFile::TargetFile(file_id) = action.file {
                     db.file_text(file_id).as_ref().to_owned()
                 } else {
                     text_without_caret
                 };
+                action.edit.apply(&mut actual);
 
-                let mut actual = action.edit.apply(&assisted_file_text);
                 match action.cursor_position {
                     None => {
                         if let RangeOrOffset::Offset(before_cursor_pos) = range_or_offset {
diff --git a/crates/ra_ide/src/completion/completion_context.rs b/crates/ra_ide/src/completion/completion_context.rs
index dd87bd119..b6b9627de 100644
--- a/crates/ra_ide/src/completion/completion_context.rs
+++ b/crates/ra_ide/src/completion/completion_context.rs
@@ -9,7 +9,7 @@ use ra_syntax::{
     SyntaxKind::*,
     SyntaxNode, SyntaxToken, TextRange, TextSize,
 };
-use ra_text_edit::AtomTextEdit;
+use ra_text_edit::Indel;
 
 use crate::{call_info::ActiveParameter, completion::CompletionConfig, FilePosition};
 
@@ -76,7 +76,7 @@ impl<'a> CompletionContext<'a> {
         // actual completion.
         let file_with_fake_ident = {
             let parse = db.parse(position.file_id);
-            let edit = AtomTextEdit::insert(position.offset, "intellijRulezz".to_string());
+            let edit = Indel::insert(position.offset, "intellijRulezz".to_string());
             parse.reparse(&edit).tree()
         };
         let fake_ident_token =
diff --git a/crates/ra_ide/src/completion/completion_item.rs b/crates/ra_ide/src/completion/completion_item.rs
index 5936fb8f7..383b23ac4 100644
--- a/crates/ra_ide/src/completion/completion_item.rs
+++ b/crates/ra_ide/src/completion/completion_item.rs
@@ -62,8 +62,8 @@ impl fmt::Debug for CompletionItem {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let mut s = f.debug_struct("CompletionItem");
         s.field("label", &self.label()).field("source_range", &self.source_range());
-        if self.text_edit().as_atoms().len() == 1 {
-            let atom = &self.text_edit().as_atoms()[0];
+        if self.text_edit().as_indels().len() == 1 {
+            let atom = &self.text_edit().as_indels()[0];
             s.field("delete", &atom.delete);
             s.field("insert", &atom.insert);
         } else {
diff --git a/crates/ra_ide/src/diagnostics.rs b/crates/ra_ide/src/diagnostics.rs
index 4c04cee07..87a0b80f1 100644
--- a/crates/ra_ide/src/diagnostics.rs
+++ b/crates/ra_ide/src/diagnostics.rs
@@ -241,7 +241,11 @@ mod tests {
             diagnostics.pop().unwrap_or_else(|| panic!("no diagnostics for:\n{}\n", before));
         let mut fix = diagnostic.fix.unwrap();
         let edit = fix.source_file_edits.pop().unwrap().edit;
-        let actual = edit.apply(&before);
+        let actual = {
+            let mut actual = before.to_string();
+            edit.apply(&mut actual);
+            actual
+        };
         assert_eq_text!(after, &actual);
     }
 
@@ -256,7 +260,11 @@ mod tests {
         let mut fix = diagnostic.fix.unwrap();
         let edit = fix.source_file_edits.pop().unwrap().edit;
         let target_file_contents = analysis.file_text(file_position.file_id).unwrap();
-        let actual = edit.apply(&target_file_contents);
+        let actual = {
+            let mut actual = target_file_contents.to_string();
+            edit.apply(&mut actual);
+            actual
+        };
 
         // Strip indent and empty lines from `after`, to match the behaviour of
         // `parse_fixture` called from `analysis_and_position`.
@@ -288,7 +296,11 @@ mod tests {
         let diagnostic = analysis.diagnostics(file_id).unwrap().pop().unwrap();
         let mut fix = diagnostic.fix.unwrap();
         let edit = fix.source_file_edits.pop().unwrap().edit;
-        let actual = edit.apply(&before);
+        let actual = {
+            let mut actual = before.to_string();
+            edit.apply(&mut actual);
+            actual
+        };
         assert_eq_text!(after, &actual);
     }
 
@@ -662,10 +674,10 @@ mod tests {
                                     1,
                                 ),
                                 edit: TextEdit {
-                                    atoms: [
-                                        AtomTextEdit {
-                                            delete: 3..9,
+                                    indels: [
+                                        Indel {
                                             insert: "{a:42, b: ()}",
+                                            delete: 3..9,
                                         },
                                     ],
                                 },
diff --git a/crates/ra_ide/src/join_lines.rs b/crates/ra_ide/src/join_lines.rs
index 63fd6b3e4..d3af780c4 100644
--- a/crates/ra_ide/src/join_lines.rs
+++ b/crates/ra_ide/src/join_lines.rs
@@ -569,7 +569,11 @@ fn foo() {
         let (sel, before) = extract_range(before);
         let parse = SourceFile::parse(&before);
         let result = join_lines(&parse.tree(), sel);
-        let actual = result.apply(&before);
+        let actual = {
+            let mut actual = before.to_string();
+            result.apply(&mut actual);
+            actual
+        };
         assert_eq_text!(after, &actual);
     }
 
diff --git a/crates/ra_ide/src/references/rename.rs b/crates/ra_ide/src/references/rename.rs
index 52e55b0a0..0398d53bc 100644
--- a/crates/ra_ide/src/references/rename.rs
+++ b/crates/ra_ide/src/references/rename.rs
@@ -537,10 +537,10 @@ mod tests {
                                 2,
                             ),
                             edit: TextEdit {
-                                atoms: [
-                                    AtomTextEdit {
-                                        delete: 4..7,
+                                indels: [
+                                    Indel {
                                         insert: "foo2",
+                                        delete: 4..7,
                                     },
                                 ],
                             },
@@ -589,10 +589,10 @@ mod tests {
                                 1,
                             ),
                             edit: TextEdit {
-                                atoms: [
-                                    AtomTextEdit {
-                                        delete: 4..7,
+                                indels: [
+                                    Indel {
                                         insert: "foo2",
+                                        delete: 4..7,
                                     },
                                 ],
                             },
@@ -672,10 +672,10 @@ mod tests {
                                 2,
                             ),
                             edit: TextEdit {
-                                atoms: [
-                                    AtomTextEdit {
-                                        delete: 8..11,
+                                indels: [
+                                    Indel {
                                         insert: "foo2",
+                                        delete: 8..11,
                                     },
                                 ],
                             },
@@ -685,10 +685,10 @@ mod tests {
                                 1,
                             ),
                             edit: TextEdit {
-                                atoms: [
-                                    AtomTextEdit {
-                                        delete: 27..30,
+                                indels: [
+                                    Indel {
                                         insert: "foo2",
+                                        delete: 27..30,
                                     },
                                 ],
                             },
@@ -720,13 +720,13 @@ mod tests {
         if let Some(change) = source_change {
             for edit in change.info.source_file_edits {
                 file_id = Some(edit.file_id);
-                for atom in edit.edit.as_atoms() {
-                    text_edit_builder.replace(atom.delete, atom.insert.clone());
+                for indel in edit.edit.as_indels() {
+                    text_edit_builder.replace(indel.delete, indel.insert.clone());
                 }
             }
         }
-        let result =
-            text_edit_builder.finish().apply(&*analysis.file_text(file_id.unwrap()).unwrap());
+        let mut result = analysis.file_text(file_id.unwrap()).unwrap().to_string();
+        text_edit_builder.finish().apply(&mut result);
         assert_eq_text!(expected, &*result);
     }
 }
diff --git a/crates/ra_ide/src/ssr.rs b/crates/ra_ide/src/ssr.rs
index 7b93ff2d2..8bf52d0fa 100644
--- a/crates/ra_ide/src/ssr.rs
+++ b/crates/ra_ide/src/ssr.rs
@@ -401,16 +401,22 @@ fn render_replace(
     ignored_comments: &Vec<Comment>,
     template: &SsrTemplate,
 ) -> String {
-    let mut builder = TextEditBuilder::default();
-    for element in template.template.descendants() {
-        if let Some(var) = template.placeholders.get(&element) {
-            builder.replace(element.text_range(), binding[var].to_string())
+    let edit = {
+        let mut builder = TextEditBuilder::default();
+        for element in template.template.descendants() {
+            if let Some(var) = template.placeholders.get(&element) {
+                builder.replace(element.text_range(), binding[var].to_string())
+            }
         }
-    }
-    for comment in ignored_comments {
-        builder.insert(template.template.text_range().end(), comment.syntax().to_string())
-    }
-    builder.finish().apply(&template.template.text().to_string())
+        for comment in ignored_comments {
+            builder.insert(template.template.text_range().end(), comment.syntax().to_string())
+        }
+        builder.finish()
+    };
+
+    let mut text = template.template.text().to_string();
+    edit.apply(&mut text);
+    text
 }
 
 #[cfg(test)]
@@ -505,7 +511,9 @@ mod tests {
         );
 
         let edit = replace(&matches, &query.template);
-        assert_eq!(edit.apply(input), "fn main() { bar(1+2); }");
+        let mut after = input.to_string();
+        edit.apply(&mut after);
+        assert_eq!(after, "fn main() { bar(1+2); }");
     }
 
     fn assert_ssr_transform(query: &str, input: &str, result: &str) {
@@ -513,7 +521,9 @@ mod tests {
         let code = SourceFile::parse(input).tree();
         let matches = find(&query.pattern, code.syntax());
         let edit = replace(&matches, &query.template);
-        assert_eq!(edit.apply(input), result);
+        let mut after = input.to_string();
+        edit.apply(&mut after);
+        assert_eq!(after, result);
     }
 
     #[test]
diff --git a/crates/ra_ide/src/test_utils.rs b/crates/ra_ide/src/test_utils.rs
index f14533e14..48c8fd1f4 100644
--- a/crates/ra_ide/src/test_utils.rs
+++ b/crates/ra_ide/src/test_utils.rs
@@ -13,7 +13,11 @@ pub fn check_action<F: Fn(&SourceFile, TextSize) -> Option<TextEdit>>(
     let (before_cursor_pos, before) = extract_offset(before);
     let file = SourceFile::parse(&before).ok().unwrap();
     let result = f(&file, before_cursor_pos).expect("code action is not applicable");
-    let actual = result.apply(&before);
+    let actual = {
+        let mut actual = before.to_string();
+        result.apply(&mut actual);
+        actual
+    };
     let actual_cursor_pos =
         result.apply_to_offset(before_cursor_pos).expect("cursor position is affected by the edit");
     let actual = add_cursor(&actual, actual_cursor_pos);
diff --git a/crates/ra_ide/src/typing.rs b/crates/ra_ide/src/typing.rs
index 2a8b4327f..a03da4693 100644
--- a/crates/ra_ide/src/typing.rs
+++ b/crates/ra_ide/src/typing.rs
@@ -142,10 +142,13 @@ mod tests {
     fn do_type_char(char_typed: char, before: &str) -> Option<(String, SingleFileChange)> {
         let (offset, before) = extract_offset(before);
         let edit = TextEdit::insert(offset, char_typed.to_string());
-        let before = edit.apply(&before);
+        let mut before = before.to_string();
+        edit.apply(&mut before);
         let parse = SourceFile::parse(&before);
-        on_char_typed_inner(&parse.tree(), offset, char_typed)
-            .map(|it| (it.edit.apply(&before), it))
+        on_char_typed_inner(&parse.tree(), offset, char_typed).map(|it| {
+            it.edit.apply(&mut before);
+            (before.to_string(), it)
+        })
     }
 
     fn type_char(char_typed: char, before: &str, after: &str) {
diff --git a/crates/ra_ide/src/typing/on_enter.rs b/crates/ra_ide/src/typing/on_enter.rs
index 725237464..78a40cc94 100644
--- a/crates/ra_ide/src/typing/on_enter.rs
+++ b/crates/ra_ide/src/typing/on_enter.rs
@@ -96,7 +96,8 @@ mod tests {
         let result = analysis.on_enter(FilePosition { offset, file_id }).unwrap()?;
 
         assert_eq!(result.source_file_edits.len(), 1);
-        let actual = result.source_file_edits[0].edit.apply(&before);
+        let mut actual = before.to_string();
+        result.source_file_edits[0].edit.apply(&mut actual);
         let actual = add_cursor(&actual, result.cursor_position.unwrap().offset);
         Some(actual)
     }
diff --git a/crates/ra_ide_db/src/line_index_utils.rs b/crates/ra_ide_db/src/line_index_utils.rs
index 039a12c0d..7fa6fc448 100644
--- a/crates/ra_ide_db/src/line_index_utils.rs
+++ b/crates/ra_ide_db/src/line_index_utils.rs
@@ -10,7 +10,7 @@
 use std::convert::TryInto;
 
 use ra_syntax::{TextRange, TextSize};
-use ra_text_edit::{AtomTextEdit, TextEdit};
+use ra_text_edit::{Indel, TextEdit};
 
 use crate::line_index::{LineCol, LineIndex, Utf16Char};
 
@@ -182,14 +182,14 @@ struct TranslatedEdit<'a> {
 }
 
 struct Edits<'a> {
-    edits: &'a [AtomTextEdit],
+    edits: &'a [Indel],
     current: Option<TranslatedEdit<'a>>,
     acc_diff: i64,
 }
 
 impl<'a> Edits<'a> {
     fn from_text_edit(text_edit: &'a TextEdit) -> Edits<'a> {
-        let mut x = Edits { edits: text_edit.as_atoms(), current: None, acc_diff: 0 };
+        let mut x = Edits { edits: text_edit.as_indels(), current: None, acc_diff: 0 };
         x.advance_edit();
         x
     }
diff --git a/crates/ra_syntax/src/fuzz.rs b/crates/ra_syntax/src/fuzz.rs
index 10fbe3176..39f9b12ab 100644
--- a/crates/ra_syntax/src/fuzz.rs
+++ b/crates/ra_syntax/src/fuzz.rs
@@ -5,7 +5,7 @@ use std::{
     str::{self, FromStr},
 };
 
-use ra_text_edit::AtomTextEdit;
+use ra_text_edit::Indel;
 
 use crate::{validation, AstNode, SourceFile, TextRange};
 
@@ -22,7 +22,7 @@ pub fn check_parser(text: &str) {
 #[derive(Debug, Clone)]
 pub struct CheckReparse {
     text: String,
-    edit: AtomTextEdit,
+    edit: Indel,
     edited_text: String,
 }
 
@@ -43,7 +43,7 @@ impl CheckReparse {
             TextRange::at(delete_start.try_into().unwrap(), delete_len.try_into().unwrap());
         let edited_text =
             format!("{}{}{}", &text[..delete_start], &insert, &text[delete_start + delete_len..]);
-        let edit = AtomTextEdit { delete, insert };
+        let edit = Indel { delete, insert };
         Some(CheckReparse { text, edit, edited_text })
     }
 
diff --git a/crates/ra_syntax/src/lib.rs b/crates/ra_syntax/src/lib.rs
index d0234cada..61e686da5 100644
--- a/crates/ra_syntax/src/lib.rs
+++ b/crates/ra_syntax/src/lib.rs
@@ -39,7 +39,7 @@ pub mod fuzz;
 
 use std::{marker::PhantomData, sync::Arc};
 
-use ra_text_edit::AtomTextEdit;
+use ra_text_edit::Indel;
 use stdx::format_to;
 
 use crate::syntax_node::GreenNode;
@@ -126,13 +126,13 @@ impl Parse<SourceFile> {
         buf
     }
 
-    pub fn reparse(&self, edit: &AtomTextEdit) -> Parse<SourceFile> {
-        self.incremental_reparse(edit).unwrap_or_else(|| self.full_reparse(edit))
+    pub fn reparse(&self, indel: &Indel) -> Parse<SourceFile> {
+        self.incremental_reparse(indel).unwrap_or_else(|| self.full_reparse(indel))
     }
 
-    fn incremental_reparse(&self, edit: &AtomTextEdit) -> Option<Parse<SourceFile>> {
+    fn incremental_reparse(&self, indel: &Indel) -> Option<Parse<SourceFile>> {
         // FIXME: validation errors are not handled here
-        parsing::incremental_reparse(self.tree().syntax(), edit, self.errors.to_vec()).map(
+        parsing::incremental_reparse(self.tree().syntax(), indel, self.errors.to_vec()).map(
             |(green_node, errors, _reparsed_range)| Parse {
                 green: green_node,
                 errors: Arc::new(errors),
@@ -141,8 +141,9 @@ impl Parse<SourceFile> {
         )
     }
 
-    fn full_reparse(&self, edit: &AtomTextEdit) -> Parse<SourceFile> {
-        let text = edit.apply(self.tree().syntax().text().to_string());
+    fn full_reparse(&self, indel: &Indel) -> Parse<SourceFile> {
+        let mut text = self.tree().syntax().text().to_string();
+        indel.apply(&mut text);
         SourceFile::parse(&text)
     }
 }
diff --git a/crates/ra_syntax/src/parsing/reparsing.rs b/crates/ra_syntax/src/parsing/reparsing.rs
index ffff0a7b2..edbc190f8 100644
--- a/crates/ra_syntax/src/parsing/reparsing.rs
+++ b/crates/ra_syntax/src/parsing/reparsing.rs
@@ -7,7 +7,7 @@
 //!     and try to parse only this block.
 
 use ra_parser::Reparser;
-use ra_text_edit::AtomTextEdit;
+use ra_text_edit::Indel;
 
 use crate::{
     algo,
@@ -24,7 +24,7 @@ use crate::{
 
 pub(crate) fn incremental_reparse(
     node: &SyntaxNode,
-    edit: &AtomTextEdit,
+    edit: &Indel,
     errors: Vec<SyntaxError>,
 ) -> Option<(GreenNode, Vec<SyntaxError>, TextRange)> {
     if let Some((green, new_errors, old_range)) = reparse_token(node, &edit) {
@@ -39,7 +39,7 @@ pub(crate) fn incremental_reparse(
 
 fn reparse_token<'node>(
     root: &'node SyntaxNode,
-    edit: &AtomTextEdit,
+    edit: &Indel,
 ) -> Option<(GreenNode, Vec<SyntaxError>, TextRange)> {
     let prev_token = algo::find_covering_element(root, edit.delete).as_token()?.clone();
     let prev_token_kind = prev_token.kind();
@@ -88,7 +88,7 @@ fn reparse_token<'node>(
 
 fn reparse_block<'node>(
     root: &'node SyntaxNode,
-    edit: &AtomTextEdit,
+    edit: &Indel,
 ) -> Option<(GreenNode, Vec<SyntaxError>, TextRange)> {
     let (node, reparser) = find_reparsable_node(root, edit.delete)?;
     let text = get_text_after_edit(node.clone().into(), edit);
@@ -108,15 +108,15 @@ fn reparse_block<'node>(
     Some((node.replace_with(green), new_parser_errors, node.text_range()))
 }
 
-fn get_text_after_edit(element: SyntaxElement, edit: &AtomTextEdit) -> String {
-    let edit =
-        AtomTextEdit::replace(edit.delete - element.text_range().start(), edit.insert.clone());
+fn get_text_after_edit(element: SyntaxElement, edit: &Indel) -> String {
+    let edit = Indel::replace(edit.delete - element.text_range().start(), edit.insert.clone());
 
-    let text = match element {
+    let mut text = match element {
         NodeOrToken::Token(token) => token.text().to_string(),
         NodeOrToken::Node(node) => node.text().to_string(),
     };
-    edit.apply(text)
+    edit.apply(&mut text);
+    text
 }
 
 fn is_contextual_kw(text: &str) -> bool {
@@ -167,7 +167,7 @@ fn merge_errors(
     old_errors: Vec<SyntaxError>,
     new_errors: Vec<SyntaxError>,
     range_before_reparse: TextRange,
-    edit: &AtomTextEdit,
+    edit: &Indel,
 ) -> Vec<SyntaxError> {
     let mut res = Vec::new();
 
@@ -198,8 +198,12 @@ mod tests {
 
     fn do_check(before: &str, replace_with: &str, reparsed_len: u32) {
         let (range, before) = extract_range(before);
-        let edit = AtomTextEdit::replace(range, replace_with.to_owned());
-        let after = edit.apply(before.clone());
+        let edit = Indel::replace(range, replace_with.to_owned());
+        let after = {
+            let mut after = before.clone();
+            edit.apply(&mut after);
+            after
+        };
 
         let fully_reparsed = SourceFile::parse(&after);
         let incrementally_reparsed: Parse<SourceFile> = {
diff --git a/crates/ra_text_edit/src/lib.rs b/crates/ra_text_edit/src/lib.rs
index e656260c7..7138bbc65 100644
--- a/crates/ra_text_edit/src/lib.rs
+++ b/crates/ra_text_edit/src/lib.rs
@@ -1,36 +1,144 @@
-//! FIXME: write short doc here
-
-mod text_edit;
+//! Representation of a `TextEdit`.
+//!
+//! `rust-analyzer` never mutates text itself and only sends diffs to clients,
+//! so `TextEdit` is the ultimate representation of the work done by
+//! rust-analyzer.
 
 use text_size::{TextRange, TextSize};
 
-pub use crate::text_edit::{TextEdit, TextEditBuilder};
-
-/// Must not overlap with other `AtomTextEdit`s
+/// `InsertDelete` -- a single "atomic" change to text
+///
+/// Must not overlap with other `InDel`s
 #[derive(Debug, Clone)]
-pub struct AtomTextEdit {
+pub struct Indel {
+    pub insert: String,
     /// Refers to offsets in the original text
     pub delete: TextRange,
-    pub insert: String,
 }
 
-impl AtomTextEdit {
-    pub fn replace(range: TextRange, replace_with: String) -> AtomTextEdit {
-        AtomTextEdit { delete: range, insert: replace_with }
-    }
+#[derive(Debug, Clone)]
+pub struct TextEdit {
+    indels: Vec<Indel>,
+}
 
-    pub fn delete(range: TextRange) -> AtomTextEdit {
-        AtomTextEdit::replace(range, String::new())
-    }
+#[derive(Debug, Default)]
+pub struct TextEditBuilder {
+    indels: Vec<Indel>,
+}
 
-    pub fn insert(offset: TextSize, text: String) -> AtomTextEdit {
-        AtomTextEdit::replace(TextRange::empty(offset), text)
+impl Indel {
+    pub fn insert(offset: TextSize, text: String) -> Indel {
+        Indel::replace(TextRange::empty(offset), text)
+    }
+    pub fn delete(range: TextRange) -> Indel {
+        Indel::replace(range, String::new())
+    }
+    pub fn replace(range: TextRange, replace_with: String) -> Indel {
+        Indel { delete: range, insert: replace_with }
     }
 
-    pub fn apply(&self, mut text: String) -> String {
+    pub fn apply(&self, text: &mut String) {
         let start: usize = self.delete.start().into();
         let end: usize = self.delete.end().into();
         text.replace_range(start..end, &self.insert);
-        text
+    }
+}
+
+impl TextEdit {
+    pub fn insert(offset: TextSize, text: String) -> TextEdit {
+        let mut builder = TextEditBuilder::default();
+        builder.insert(offset, text);
+        builder.finish()
+    }
+
+    pub fn delete(range: TextRange) -> TextEdit {
+        let mut builder = TextEditBuilder::default();
+        builder.delete(range);
+        builder.finish()
+    }
+
+    pub fn replace(range: TextRange, replace_with: String) -> TextEdit {
+        let mut builder = TextEditBuilder::default();
+        builder.replace(range, replace_with);
+        builder.finish()
+    }
+
+    pub(crate) fn from_indels(mut indels: Vec<Indel>) -> TextEdit {
+        indels.sort_by_key(|a| (a.delete.start(), a.delete.end()));
+        for (a1, a2) in indels.iter().zip(indels.iter().skip(1)) {
+            assert!(a1.delete.end() <= a2.delete.start())
+        }
+        TextEdit { indels }
+    }
+
+    pub fn as_indels(&self) -> &[Indel] {
+        &self.indels
+    }
+
+    pub fn apply(&self, text: &mut String) {
+        match self.indels.len() {
+            0 => return,
+            1 => {
+                self.indels[0].apply(text);
+                return;
+            }
+            _ => (),
+        }
+
+        let mut total_len = TextSize::of(&*text);
+        for indel in self.indels.iter() {
+            total_len += TextSize::of(&indel.insert);
+            total_len -= indel.delete.end() - indel.delete.start();
+        }
+        let mut buf = String::with_capacity(total_len.into());
+        let mut prev = 0;
+        for indel in self.indels.iter() {
+            let start: usize = indel.delete.start().into();
+            let end: usize = indel.delete.end().into();
+            if start > prev {
+                buf.push_str(&text[prev..start]);
+            }
+            buf.push_str(&indel.insert);
+            prev = end;
+        }
+        buf.push_str(&text[prev..text.len()]);
+        assert_eq!(TextSize::of(&buf), total_len);
+
+        // FIXME: figure out a way to mutate the text in-place or reuse the
+        // memory in some other way
+        *text = buf
+    }
+
+    pub fn apply_to_offset(&self, offset: TextSize) -> Option<TextSize> {
+        let mut res = offset;
+        for indel in self.indels.iter() {
+            if indel.delete.start() >= offset {
+                break;
+            }
+            if offset < indel.delete.end() {
+                return None;
+            }
+            res += TextSize::of(&indel.insert);
+            res -= indel.delete.len();
+        }
+        Some(res)
+    }
+}
+
+impl TextEditBuilder {
+    pub fn replace(&mut self, range: TextRange, replace_with: String) {
+        self.indels.push(Indel::replace(range, replace_with))
+    }
+    pub fn delete(&mut self, range: TextRange) {
+        self.indels.push(Indel::delete(range))
+    }
+    pub fn insert(&mut self, offset: TextSize, text: String) {
+        self.indels.push(Indel::insert(offset, text))
+    }
+    pub fn finish(self) -> TextEdit {
+        TextEdit::from_indels(self.indels)
+    }
+    pub fn invalidates_offset(&self, offset: TextSize) -> bool {
+        self.indels.iter().any(|indel| indel.delete.contains_inclusive(offset))
     }
 }
diff --git a/crates/ra_text_edit/src/text_edit.rs b/crates/ra_text_edit/src/text_edit.rs
deleted file mode 100644
index eabab4b4d..000000000
--- a/crates/ra_text_edit/src/text_edit.rs
+++ /dev/null
@@ -1,102 +0,0 @@
-//! FIXME: write short doc here
-
-use crate::AtomTextEdit;
-
-use text_size::{TextRange, TextSize};
-
-#[derive(Debug, Clone)]
-pub struct TextEdit {
-    atoms: Vec<AtomTextEdit>,
-}
-
-#[derive(Debug, Default)]
-pub struct TextEditBuilder {
-    atoms: Vec<AtomTextEdit>,
-}
-
-impl TextEditBuilder {
-    pub fn replace(&mut self, range: TextRange, replace_with: String) {
-        self.atoms.push(AtomTextEdit::replace(range, replace_with))
-    }
-    pub fn delete(&mut self, range: TextRange) {
-        self.atoms.push(AtomTextEdit::delete(range))
-    }
-    pub fn insert(&mut self, offset: TextSize, text: String) {
-        self.atoms.push(AtomTextEdit::insert(offset, text))
-    }
-    pub fn finish(self) -> TextEdit {
-        TextEdit::from_atoms(self.atoms)
-    }
-    pub fn invalidates_offset(&self, offset: TextSize) -> bool {
-        self.atoms.iter().any(|atom| atom.delete.contains_inclusive(offset))
-    }
-}
-
-impl TextEdit {
-    pub fn insert(offset: TextSize, text: String) -> TextEdit {
-        let mut builder = TextEditBuilder::default();
-        builder.insert(offset, text);
-        builder.finish()
-    }
-
-    pub fn delete(range: TextRange) -> TextEdit {
-        let mut builder = TextEditBuilder::default();
-        builder.delete(range);
-        builder.finish()
-    }
-
-    pub fn replace(range: TextRange, replace_with: String) -> TextEdit {
-        let mut builder = TextEditBuilder::default();
-        builder.replace(range, replace_with);
-        builder.finish()
-    }
-
-    pub(crate) fn from_atoms(mut atoms: Vec<AtomTextEdit>) -> TextEdit {
-        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())
-        }
-        TextEdit { atoms }
-    }
-
-    pub fn as_atoms(&self) -> &[AtomTextEdit] {
-        &self.atoms
-    }
-
-    pub fn apply(&self, text: &str) -> String {
-        let mut total_len = TextSize::of(text);
-        for atom in self.atoms.iter() {
-            total_len += TextSize::of(&atom.insert);
-            total_len -= atom.delete.end() - atom.delete.start();
-        }
-        let mut buf = String::with_capacity(total_len.into());
-        let mut prev = 0;
-        for atom in self.atoms.iter() {
-            let start: usize = atom.delete.start().into();
-            let end: usize = atom.delete.end().into();
-            if start > prev {
-                buf.push_str(&text[prev..start]);
-            }
-            buf.push_str(&atom.insert);
-            prev = end;
-        }
-        buf.push_str(&text[prev..text.len()]);
-        assert_eq!(TextSize::of(&buf), total_len);
-        buf
-    }
-
-    pub fn apply_to_offset(&self, offset: TextSize) -> Option<TextSize> {
-        let mut res = offset;
-        for atom in self.atoms.iter() {
-            if atom.delete.start() >= offset {
-                break;
-            }
-            if offset < atom.delete.end() {
-                return None;
-            }
-            res += TextSize::of(&atom.insert);
-            res -= atom.delete.len();
-        }
-        Some(res)
-    }
-}
diff --git a/crates/rust-analyzer/src/conv.rs b/crates/rust-analyzer/src/conv.rs
index 7be5ebcdb..f64c90b5b 100644
--- a/crates/rust-analyzer/src/conv.rs
+++ b/crates/rust-analyzer/src/conv.rs
@@ -15,7 +15,7 @@ use ra_ide::{
     ReferenceAccess, Severity, SourceChange, SourceFileEdit,
 };
 use ra_syntax::{SyntaxKind, TextRange, TextSize};
-use ra_text_edit::{AtomTextEdit, TextEdit};
+use ra_text_edit::{Indel, TextEdit};
 use ra_vfs::LineEndings;
 
 use crate::{
@@ -124,23 +124,22 @@ impl ConvWith<(&LineIndex, LineEndings)> for CompletionItem {
         let mut text_edit = None;
         // LSP does not allow arbitrary edits in completion, so we have to do a
         // non-trivial mapping here.
-        for atom_edit in self.text_edit().as_atoms() {
-            if atom_edit.delete.contains_range(self.source_range()) {
-                text_edit = Some(if atom_edit.delete == self.source_range() {
-                    atom_edit.conv_with((ctx.0, ctx.1))
+        for indel in self.text_edit().as_indels() {
+            if indel.delete.contains_range(self.source_range()) {
+                text_edit = Some(if indel.delete == self.source_range() {
+                    indel.conv_with((ctx.0, ctx.1))
                 } else {
-                    assert!(self.source_range().end() == atom_edit.delete.end());
-                    let range1 =
-                        TextRange::new(atom_edit.delete.start(), self.source_range().start());
+                    assert!(self.source_range().end() == indel.delete.end());
+                    let range1 = TextRange::new(indel.delete.start(), self.source_range().start());
                     let range2 = self.source_range();
-                    let edit1 = AtomTextEdit::replace(range1, String::new());
-                    let edit2 = AtomTextEdit::replace(range2, atom_edit.insert.clone());
+                    let edit1 = Indel::replace(range1, String::new());
+                    let edit2 = Indel::replace(range2, indel.insert.clone());
                     additional_text_edits.push(edit1.conv_with((ctx.0, ctx.1)));
                     edit2.conv_with((ctx.0, ctx.1))
                 })
             } else {
-                assert!(self.source_range().intersect(atom_edit.delete).is_none());
-                additional_text_edits.push(atom_edit.conv_with((ctx.0, ctx.1)));
+                assert!(self.source_range().intersect(indel.delete).is_none());
+                additional_text_edits.push(indel.conv_with((ctx.0, ctx.1)));
             }
         }
         let text_edit = text_edit.unwrap();
@@ -257,11 +256,11 @@ impl ConvWith<(&LineIndex, LineEndings)> for TextEdit {
     type Output = Vec<lsp_types::TextEdit>;
 
     fn conv_with(self, ctx: (&LineIndex, LineEndings)) -> Vec<lsp_types::TextEdit> {
-        self.as_atoms().iter().map_conv_with(ctx).collect()
+        self.as_indels().iter().map_conv_with(ctx).collect()
     }
 }
 
-impl ConvWith<(&LineIndex, LineEndings)> for &AtomTextEdit {
+impl ConvWith<(&LineIndex, LineEndings)> for &Indel {
     type Output = lsp_types::TextEdit;
 
     fn conv_with(
@@ -522,7 +521,7 @@ impl TryConvWith<&WorldSnapshot> for SourceFileEdit {
         let line_index = world.analysis().file_line_index(self.file_id)?;
         let line_endings = world.file_line_endings(self.file_id);
         let edits =
-            self.edit.as_atoms().iter().map_conv_with((&line_index, line_endings)).collect();
+            self.edit.as_indels().iter().map_conv_with((&line_index, line_endings)).collect();
         Ok(TextDocumentEdit { text_document, edits })
     }
 }
diff --git a/xtask/tests/tidy-tests/main.rs b/xtask/tests/tidy-tests/main.rs
index ead642acc..3213c4dfa 100644
--- a/xtask/tests/tidy-tests/main.rs
+++ b/xtask/tests/tidy-tests/main.rs
@@ -115,7 +115,6 @@ impl TidyDocs {
             "ra_prof",
             "ra_project_model",
             "ra_syntax",
-            "ra_text_edit",
             "ra_tt",
             "ra_hir_ty",
         ];