src/tools/rust-analyzer/crates/ide/src/join_lines.rs - third_party/rust - Git at Google

 use ide_assists::utils::extract_trivial_expression;
 use ide_db::syntax_helpers::node_ext::expr_as_name_ref;
 use itertools::Itertools;
 use syntax::{
     ast::{self, AstNode, AstToken, IsString},
     NodeOrToken, SourceFile, SyntaxElement,
     SyntaxKind::{self, USE_TREE, WHITESPACE},
     SyntaxToken, TextRange, TextSize, T,
 };

 use text_edit::{TextEdit, TextEditBuilder};

 pub struct JoinLinesConfig {
     pub join_else_if: bool,
     pub remove_trailing_comma: bool,
     pub unwrap_trivial_blocks: bool,
     pub join_assignments: bool,
 }

 // Feature: Join Lines
 //
 // Join selected lines into one, smartly fixing up whitespace, trailing commas, and braces.
 //
 // See
 // https://user-images.githubusercontent.com/1711539/124515923-4504e800-dde9-11eb-8d58-d97945a1a785.gif[this gif]
 // for the cases handled specially by joined lines.
 //
 // |===
 // | Editor  | Action Name
 //
 // | VS Code | **rust-analyzer: Join lines**
 // |===
 //
 // image::https://user-images.githubusercontent.com/48062697/113020661-b6922200-917a-11eb-87c4-b75acc028f11.gif[]
 pub(crate) fn join_lines(
     config: &JoinLinesConfig,
     file: &SourceFile,
     range: TextRange,
 ) -> TextEdit {
     let range = if range.is_empty() {
         let syntax = file.syntax();
         let text = syntax.text().slice(range.start()..);
         let pos = match text.find_char('\n') {
             None => return TextEdit::builder().finish(),
             Some(pos) => pos,
         };
         TextRange::at(range.start() + pos, TextSize::of('\n'))
     } else {
         range
     };

     let mut edit = TextEdit::builder();
     match file.syntax().covering_element(range) {
         NodeOrToken::Node(node) => {
             for token in node.descendants_with_tokens().filter_map(|it| it.into_token()) {
                 remove_newlines(config, &mut edit, &token, range)
             }
         }
         NodeOrToken::Token(token) => remove_newlines(config, &mut edit, &token, range),
     };
     edit.finish()
 }

 fn remove_newlines(
     config: &JoinLinesConfig,
     edit: &mut TextEditBuilder,
     token: &SyntaxToken,
     range: TextRange,
 ) {
     let intersection = match range.intersect(token.text_range()) {
         Some(range) => range,
         None => return,
     };

     let range = intersection - token.text_range().start();
     let text = token.text();
     for (pos, _) in text[range].bytes().enumerate().filter(|&(_, b)| b == b'\n') {
         let pos: TextSize = (pos as u32).into();
         let offset = token.text_range().start() + range.start() + pos;
         if !edit.invalidates_offset(offset) {
             remove_newline(config, edit, token, offset);
         }
     }
 }

 fn remove_newline(
     config: &JoinLinesConfig,
     edit: &mut TextEditBuilder,
     token: &SyntaxToken,
     offset: TextSize,
 ) {
     if token.kind() != WHITESPACE || token.text().bytes().filter(|&b| b == b'\n').count() != 1 {
         let n_spaces_after_line_break = {
             let suff = &token.text()[TextRange::new(
                 offset - token.text_range().start() + TextSize::of('\n'),
                 TextSize::of(token.text()),
             )];
             suff.bytes().take_while(|&b| b == b' ').count()
         };

         let mut no_space = false;
         if let Some(string) = ast::String::cast(token.clone()) {
             if let Some(range) = string.open_quote_text_range() {
                 cov_mark::hit!(join_string_literal_open_quote);
                 no_space |= range.end() == offset;
             }
             if let Some(range) = string.close_quote_text_range() {
                 cov_mark::hit!(join_string_literal_close_quote);
                 no_space |= range.start()
                     == offset
                         + TextSize::of('\n')
                         + TextSize::try_from(n_spaces_after_line_break).unwrap();
             }
         }

         let range = TextRange::at(offset, ((n_spaces_after_line_break + 1) as u32).into());
         let replace_with = if no_space { "" } else { " " };
         edit.replace(range, replace_with.to_owned());
         return;
     }

     // The node is between two other nodes
     let (prev, next) = match (token.prev_sibling_or_token(), token.next_sibling_or_token()) {
         (Some(prev), Some(next)) => (prev, next),
         _ => return,
     };

     if config.remove_trailing_comma && prev.kind() == T![,] {
         match next.kind() {
             T![')'] | T![']'] => {
                 // Removes: trailing comma, newline (incl. surrounding whitespace)
                 edit.delete(TextRange::new(prev.text_range().start(), token.text_range().end()));
                 return;
             }
             T!['}'] => {
                 // Removes: comma, newline (incl. surrounding whitespace)
                 let space = match prev.prev_sibling_or_token() {
                     Some(left) => compute_ws(left.kind(), next.kind()),
                     None => " ",
                 };
                 edit.replace(
                     TextRange::new(prev.text_range().start(), token.text_range().end()),
                     space.to_owned(),
                 );
                 return;
             }
             _ => (),
         }
     }

     if config.join_else_if {
         if let (Some(prev), Some(_next)) = (as_if_expr(&prev), as_if_expr(&next)) {
             match prev.else_token() {
                 Some(_) => cov_mark::hit!(join_two_ifs_with_existing_else),
                 None => {
                     cov_mark::hit!(join_two_ifs);
                     edit.replace(token.text_range(), " else ".to_owned());
                     return;
                 }
             }
         }
     }

     if config.join_assignments && join_assignments(edit, &prev, &next).is_some() {
         return;
     }

     if config.unwrap_trivial_blocks {
         // Special case that turns something like:
         //
         // ```
         // my_function({$0
         //    <some-expr>
         // })
         // ```
         //
         // into `my_function(<some-expr>)`
         if join_single_expr_block(edit, token).is_some() {
             return;
         }
         // ditto for
         //
         // ```
         // use foo::{$0
         //    bar
         // };
         // ```
         if join_single_use_tree(edit, token).is_some() {
             return;
         }
     }

     if let (Some(_), Some(next)) = (
         prev.as_token().cloned().and_then(ast::Comment::cast),
         next.as_token().cloned().and_then(ast::Comment::cast),
     ) {
         // Removes: newline (incl. surrounding whitespace), start of the next comment
         edit.delete(TextRange::new(
             token.text_range().start(),
             next.syntax().text_range().start() + TextSize::of(next.prefix()),
         ));
         return;
     }

     // Remove newline but add a computed amount of whitespace characters
     edit.replace(token.text_range(), compute_ws(prev.kind(), next.kind()).to_owned());
 }

 fn join_single_expr_block(edit: &mut TextEditBuilder, token: &SyntaxToken) -> Option<()> {
     let block_expr = ast::BlockExpr::cast(token.parent_ancestors().nth(1)?)?;
     if !block_expr.is_standalone() {
         return None;
     }
     let expr = extract_trivial_expression(&block_expr)?;

     let block_range = block_expr.syntax().text_range();
     let mut buf = expr.syntax().text().to_string();

     // Match block needs to have a comma after the block
     if let Some(match_arm) = block_expr.syntax().parent().and_then(ast::MatchArm::cast) {
         if match_arm.comma_token().is_none() {
             buf.push(',');
         }
     }

     edit.replace(block_range, buf);

     Some(())
 }

 fn join_single_use_tree(edit: &mut TextEditBuilder, token: &SyntaxToken) -> Option<()> {
     let use_tree_list = ast::UseTreeList::cast(token.parent()?)?;
     let (tree,) = use_tree_list.use_trees().collect_tuple()?;
     edit.replace(use_tree_list.syntax().text_range(), tree.syntax().text().to_string());
     Some(())
 }

 fn join_assignments(
     edit: &mut TextEditBuilder,
     prev: &SyntaxElement,
     next: &SyntaxElement,
 ) -> Option<()> {
     let let_stmt = ast::LetStmt::cast(prev.as_node()?.clone())?;
     if let_stmt.eq_token().is_some() {
         cov_mark::hit!(join_assignments_already_initialized);
         return None;
     }
     let let_ident_pat = match let_stmt.pat()? {
         ast::Pat::IdentPat(it) => it,
         _ => return None,
     };

     let expr_stmt = ast::ExprStmt::cast(next.as_node()?.clone())?;
     let bin_expr = match expr_stmt.expr()? {
         ast::Expr::BinExpr(it) => it,
         _ => return None,
     };
     if !matches!(bin_expr.op_kind()?, ast::BinaryOp::Assignment { op: None }) {
         return None;
     }
     let lhs = bin_expr.lhs()?;
     let name_ref = expr_as_name_ref(&lhs)?;

     if name_ref.to_string() != let_ident_pat.syntax().to_string() {
         cov_mark::hit!(join_assignments_mismatch);
         return None;
     }

     edit.delete(let_stmt.semicolon_token()?.text_range().cover(lhs.syntax().text_range()));
     Some(())
 }

 fn as_if_expr(element: &SyntaxElement) -> Option<ast::IfExpr> {
     let mut node = element.as_node()?.clone();
     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
         node = stmt.expr()?.syntax().clone();
     }
     ast::IfExpr::cast(node)
 }

 fn compute_ws(left: SyntaxKind, right: SyntaxKind) -> &'static str {
     match left {
         T!['('] | T!['['] => return "",
         T!['{'] => {
             if let USE_TREE = right {
                 return "";
             }
         }
         _ => (),
     }
     match right {
         T![')'] | T![']'] => return "",
         T!['}'] => {
             if let USE_TREE = left {
                 return "";
             }
         }
         T![.] => return "",
         _ => (),
     }
     " "
 }

 #[cfg(test)]
 mod tests {
     use test_utils::{add_cursor, assert_eq_text, extract_offset, extract_range};

     use super::*;

     fn check_join_lines(ra_fixture_before: &str, ra_fixture_after: &str) {
         let config = JoinLinesConfig {
             join_else_if: true,
             remove_trailing_comma: true,
             unwrap_trivial_blocks: true,
             join_assignments: true,
         };

         let (before_cursor_pos, before) = extract_offset(ra_fixture_before);
         let file = SourceFile::parse(&before, span::Edition::CURRENT).ok().unwrap();

         let range = TextRange::empty(before_cursor_pos);
         let result = join_lines(&config, &file, range);

         let actual = {
             let mut actual = before;
             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);
         assert_eq_text!(ra_fixture_after, &actual);
     }

     fn check_join_lines_sel(ra_fixture_before: &str, ra_fixture_after: &str) {
         let config = JoinLinesConfig {
             join_else_if: true,
             remove_trailing_comma: true,
             unwrap_trivial_blocks: true,
             join_assignments: true,
         };

         let (sel, before) = extract_range(ra_fixture_before);
         let parse = SourceFile::parse(&before, span::Edition::CURRENT);
         let result = join_lines(&config, &parse.tree(), sel);
         let actual = {
             let mut actual = before;
             result.apply(&mut actual);
             actual
         };
         assert_eq_text!(ra_fixture_after, &actual);
     }

     #[test]
     fn test_join_lines_comma() {
         check_join_lines(
             r"
 fn foo() {
     $0foo(1,
     )
 }
 ",
             r"
 fn foo() {
     $0foo(1)
 }
 ",
         );
     }

     #[test]
     fn test_join_lines_lambda_block() {
         check_join_lines(
             r"
 pub fn reparse(&self, edit: &AtomTextEdit) -> File {
     $0self.incremental_reparse(edit).unwrap_or_else(|| {
         self.full_reparse(edit)
     })
 }
 ",
             r"
 pub fn reparse(&self, edit: &AtomTextEdit) -> File {
     $0self.incremental_reparse(edit).unwrap_or_else(|| self.full_reparse(edit))
 }
 ",
         );
     }

     #[test]
     fn test_join_lines_block() {
         check_join_lines(
             r"
 fn foo() {
     foo($0{
         92
     })
 }",
             r"
 fn foo() {
     foo($092)
 }",
         );
     }

     #[test]
     fn test_join_lines_diverging_block() {
         check_join_lines(
             r"
 fn foo() {
     loop {
         match x {
             92 => $0{
                 continue;
             }
         }
     }
 }
         ",
             r"
 fn foo() {
     loop {
         match x {
             92 => $0continue,
         }
     }
 }
         ",
         );
     }

     #[test]
     fn join_lines_adds_comma_for_block_in_match_arm() {
         check_join_lines(
             r"
 fn foo(e: Result<U, V>) {
     match e {
         Ok(u) => $0{
             u.foo()
         }
         Err(v) => v,
     }
 }",
             r"
 fn foo(e: Result<U, V>) {
     match e {
         Ok(u) => $0u.foo(),
         Err(v) => v,
     }
 }",
         );
     }

     #[test]
     fn join_lines_multiline_in_block() {
         check_join_lines(
             r"
 fn foo() {
     match ty {
         $0 Some(ty) => {
             match ty {
                 _ => false,
             }
         }
         _ => true,
     }
 }
 ",
             r"
 fn foo() {
     match ty {
         $0 Some(ty) => match ty {
                 _ => false,
             },
         _ => true,
     }
 }
 ",
         );
     }

     #[test]
     fn join_lines_keeps_comma_for_block_in_match_arm() {
         // We already have a comma
         check_join_lines(
             r"
 fn foo(e: Result<U, V>) {
     match e {
         Ok(u) => $0{
             u.foo()
         },
         Err(v) => v,
     }
 }",
             r"
 fn foo(e: Result<U, V>) {
     match e {
         Ok(u) => $0u.foo(),
         Err(v) => v,
     }
 }",
         );

         // comma with whitespace between brace and ,
         check_join_lines(
             r"
 fn foo(e: Result<U, V>) {
     match e {
         Ok(u) => $0{
             u.foo()
         }    ,
         Err(v) => v,
     }
 }",
             r"
 fn foo(e: Result<U, V>) {
     match e {
         Ok(u) => $0u.foo()    ,
         Err(v) => v,
     }
 }",
         );

         // comma with newline between brace and ,
         check_join_lines(
             r"
 fn foo(e: Result<U, V>) {
     match e {
         Ok(u) => $0{
             u.foo()
         }
         ,
         Err(v) => v,
     }
 }",
             r"
 fn foo(e: Result<U, V>) {
     match e {
         Ok(u) => $0u.foo()
         ,
         Err(v) => v,
     }
 }",
         );
     }

     #[test]
     fn join_lines_keeps_comma_with_single_arg_tuple() {
         // A single arg tuple
         check_join_lines(
             r"
 fn foo() {
     let x = ($0{
        4
     },);
 }",
             r"
 fn foo() {
     let x = ($04,);
 }",
         );

         // single arg tuple with whitespace between brace and comma
         check_join_lines(
             r"
 fn foo() {
     let x = ($0{
        4
     }   ,);
 }",
             r"
 fn foo() {
     let x = ($04   ,);
 }",
         );

         // single arg tuple with newline between brace and comma
         check_join_lines(
             r"
 fn foo() {
     let x = ($0{
        4
     }
     ,);
 }",
             r"
 fn foo() {
     let x = ($04
     ,);
 }",
         );
     }

     #[test]
     fn test_join_lines_use_items_left() {
         // No space after the '{'
         check_join_lines(
             r"
 $0use syntax::{
     TextSize, TextRange,
 };",
             r"
 $0use syntax::{TextSize, TextRange,
 };",
         );
     }

     #[test]
     fn test_join_lines_use_items_right() {
         // No space after the '}'
         check_join_lines(
             r"
 use syntax::{
 $0    TextSize, TextRange
 };",
             r"
 use syntax::{
 $0    TextSize, TextRange};",
         );
     }

     #[test]
     fn test_join_lines_use_items_right_comma() {
         // No space after the '}'
         check_join_lines(
             r"
 use syntax::{
 $0    TextSize, TextRange,
 };",
             r"
 use syntax::{
 $0    TextSize, TextRange};",
         );
     }

     #[test]
     fn test_join_lines_use_tree() {
         check_join_lines(
             r"
 use syntax::{
     algo::$0{
         find_token_at_offset,
     },
     ast,
 };",
             r"
 use syntax::{
     algo::$0find_token_at_offset,
     ast,
 };",
         );
     }

     #[test]
     fn test_join_lines_normal_comments() {
         check_join_lines(
             r"
 fn foo() {
     // Hello$0
     // world!
 }
 ",
             r"
 fn foo() {
     // Hello$0 world!
 }
 ",
         );
     }

     #[test]
     fn test_join_lines_doc_comments() {
         check_join_lines(
             r"
 fn foo() {
     /// Hello$0
     /// world!
 }
 ",
             r"
 fn foo() {
     /// Hello$0 world!
 }
 ",
         );
     }

     #[test]
     fn test_join_lines_mod_comments() {
         check_join_lines(
             r"
 fn foo() {
     //! Hello$0
     //! world!
 }
 ",
             r"
 fn foo() {
     //! Hello$0 world!
 }
 ",
         );
     }

     #[test]
     fn test_join_lines_multiline_comments_1() {
         check_join_lines(
             r"
 fn foo() {
     // Hello$0
     /* world! */
 }
 ",
             r"
 fn foo() {
     // Hello$0 world! */
 }
 ",
         );
     }

     #[test]
     fn test_join_lines_multiline_comments_2() {
         check_join_lines(
             r"
 fn foo() {
     // The$0
     /* quick
     brown
     fox! */
 }
 ",
             r"
 fn foo() {
     // The$0 quick
     brown
     fox! */
 }
 ",
         );
     }

     #[test]
     fn test_join_lines_selection_fn_args() {
         check_join_lines_sel(
             r"
 fn foo() {
     $0foo(1,
         2,
         3,
     $0)
 }
     ",
             r"
 fn foo() {
     foo(1, 2, 3)
 }
     ",
         );
     }

     #[test]
     fn test_join_lines_selection_struct() {
         check_join_lines_sel(
             r"
 struct Foo $0{
     f: u32,
 }$0
     ",
             r"
 struct Foo { f: u32 }
     ",
         );
     }

     #[test]
     fn test_join_lines_selection_dot_chain() {
         check_join_lines_sel(
             r"
 fn foo() {
     join($0type_params.type_params()
             .filter_map(|it| it.name())
             .map(|it| it.text())$0)
 }",
             r"
 fn foo() {
     join(type_params.type_params().filter_map(|it| it.name()).map(|it| it.text()))
 }",
         );
     }

     #[test]
     fn test_join_lines_selection_lambda_block_body() {
         check_join_lines_sel(
             r"
 pub fn handle_find_matching_brace() {
     params.offsets
         .map(|offset| $0{
             world.analysis().matching_brace(&file, offset).unwrap_or(offset)
         }$0)
         .collect();
 }",
             r"
 pub fn handle_find_matching_brace() {
     params.offsets
         .map(|offset| world.analysis().matching_brace(&file, offset).unwrap_or(offset))
         .collect();
 }",
         );
     }

     #[test]
     fn test_join_lines_commented_block() {
         check_join_lines(
             r"
 fn main() {
     let _ = {
         // $0foo
         // bar
         92
     };
 }
         ",
             r"
 fn main() {
     let _ = {
         // $0foo bar
         92
     };
 }
         ",
         )
     }

     #[test]
     fn join_lines_mandatory_blocks_block() {
         check_join_lines(
             r"
 $0fn foo() {
     92
 }
         ",
             r"
 $0fn foo() { 92
 }
         ",
         );

         check_join_lines(
             r"
 fn foo() {
     $0if true {
         92
     }
 }
         ",
             r"
 fn foo() {
     $0if true { 92
     }
 }
         ",
         );

         check_join_lines(
             r"
 fn foo() {
     $0loop {
         92
     }
 }
         ",
             r"
 fn foo() {
     $0loop { 92
     }
 }
         ",
         );

         check_join_lines(
             r"
 fn foo() {
     $0unsafe {
         92
     }
 }
         ",
             r"
 fn foo() {
     $0unsafe { 92
     }
 }
         ",
         );
     }

     #[test]
     fn join_string_literal() {
         {
             cov_mark::check!(join_string_literal_open_quote);
             check_join_lines(
                 r#"
 fn main() {
     $0"
 hello
 ";
 }
 "#,
                 r#"
 fn main() {
     $0"hello
 ";
 }
 "#,
             );
         }

         {
             cov_mark::check!(join_string_literal_close_quote);
             check_join_lines(
                 r#"
 fn main() {
     $0"hello
 ";
 }
 "#,
                 r#"
 fn main() {
     $0"hello";
 }
 "#,
             );
             check_join_lines(
                 r#"
 fn main() {
     $0r"hello
     ";
 }
 "#,
                 r#"
 fn main() {
     $0r"hello";
 }
 "#,
             );
         }

         check_join_lines(
             r#"
 fn main() {
     "
 $0hello
 world
 ";
 }
 "#,
             r#"
 fn main() {
     "
 $0hello world
 ";
 }
 "#,
         );
     }

     #[test]
     fn join_last_line_empty() {
         check_join_lines(
             r#"
 fn main() {$0}
 "#,
             r#"
 fn main() {$0}
 "#,
         );
     }

     #[test]
     fn join_two_ifs() {
         cov_mark::check!(join_two_ifs);
         check_join_lines(
             r#"
 fn main() {
     if foo {

     }$0
     if bar {

     }
 }
 "#,
             r#"
 fn main() {
     if foo {

     }$0 else if bar {

     }
 }
 "#,
         );
     }

     #[test]
     fn join_two_ifs_with_existing_else() {
         cov_mark::check!(join_two_ifs_with_existing_else);
         check_join_lines(
             r#"
 fn main() {
     if foo {

     } else {

     }$0
     if bar {

     }
 }
 "#,
             r#"
 fn main() {
     if foo {

     } else {

     }$0 if bar {

     }
 }
 "#,
         );
     }

     #[test]
     fn join_assignments() {
         check_join_lines(
             r#"
 fn foo() {
     $0let foo;
     foo = "bar";
 }
 "#,
             r#"
 fn foo() {
     $0let foo = "bar";
 }
 "#,
         );

         cov_mark::check!(join_assignments_mismatch);
         check_join_lines(
             r#"
 fn foo() {
     let foo;
     let qux;$0
     foo = "bar";
 }
 "#,
             r#"
 fn foo() {
     let foo;
     let qux;$0 foo = "bar";
 }
 "#,
         );

         cov_mark::check!(join_assignments_already_initialized);
         check_join_lines(
             r#"
 fn foo() {
     let foo = "bar";$0
     foo = "bar";
 }
 "#,
             r#"
 fn foo() {
     let foo = "bar";$0 foo = "bar";
 }
 "#,
         );
     }
 }
	use ide_assists::utils::extract_trivial_expression;
	use ide_db::syntax_helpers::node_ext::expr_as_name_ref;
	use itertools::Itertools;
	use syntax::{
	ast::{self, AstNode, AstToken, IsString},
	NodeOrToken, SourceFile, SyntaxElement,
	SyntaxKind::{self, USE_TREE, WHITESPACE},
	SyntaxToken, TextRange, TextSize, T,
	};

	use text_edit::{TextEdit, TextEditBuilder};

	pub struct JoinLinesConfig {
	pub join_else_if: bool,
	pub remove_trailing_comma: bool,
	pub unwrap_trivial_blocks: bool,
	pub join_assignments: bool,
	}

	// Feature: Join Lines
	//
	// Join selected lines into one, smartly fixing up whitespace, trailing commas, and braces.
	//
	// See
	// https://user-images.githubusercontent.com/1711539/124515923-4504e800-dde9-11eb-8d58-d97945a1a785.gif[this gif]
	// for the cases handled specially by joined lines.
	//
	// \|===
	// \| Editor \| Action Name
	//
	// \| VS Code \| rust-analyzer: Join lines
	// \|===
	//
	// image::https://user-images.githubusercontent.com/48062697/113020661-b6922200-917a-11eb-87c4-b75acc028f11.gif[]
	pub(crate) fn join_lines(
	config: &JoinLinesConfig,
	file: &SourceFile,
	range: TextRange,
	) -> TextEdit {
	let range = if range.is_empty() {
	let syntax = file.syntax();
	let text = syntax.text().slice(range.start()..);
	let pos = match text.find_char('\n') {
	None => return TextEdit::builder().finish(),
	Some(pos) => pos,
	};
	TextRange::at(range.start() + pos, TextSize::of('\n'))
	} else {
	range
	};

	let mut edit = TextEdit::builder();
	match file.syntax().covering_element(range) {
	NodeOrToken::Node(node) => {
	for token in node.descendants_with_tokens().filter_map(\|it\| it.into_token()) {
	remove_newlines(config, &mut edit, &token, range)
	}
	}
	NodeOrToken::Token(token) => remove_newlines(config, &mut edit, &token, range),
	};
	edit.finish()
	}

	fn remove_newlines(
	config: &JoinLinesConfig,
	edit: &mut TextEditBuilder,
	token: &SyntaxToken,
	range: TextRange,
	) {
	let intersection = match range.intersect(token.text_range()) {
	Some(range) => range,
	None => return,
	};

	let range = intersection - token.text_range().start();
	let text = token.text();
	for (pos, _) in text[range].bytes().enumerate().filter(\|&(_, b)\| b == b'\n') {
	let pos: TextSize = (pos as u32).into();
	let offset = token.text_range().start() + range.start() + pos;
	if !edit.invalidates_offset(offset) {
	remove_newline(config, edit, token, offset);
	}
	}
	}

	fn remove_newline(
	config: &JoinLinesConfig,
	edit: &mut TextEditBuilder,
	token: &SyntaxToken,
	offset: TextSize,
	) {
	if token.kind() != WHITESPACE \|\| token.text().bytes().filter(\|&b\| b == b'\n').count() != 1 {
	let n_spaces_after_line_break = {
	let suff = &token.text()[TextRange::new(
	offset - token.text_range().start() + TextSize::of('\n'),
	TextSize::of(token.text()),
	)];
	suff.bytes().take_while(\|&b\| b == b' ').count()
	};

	let mut no_space = false;
	if let Some(string) = ast::String::cast(token.clone()) {
	if let Some(range) = string.open_quote_text_range() {
	cov_mark::hit!(join_string_literal_open_quote);
	no_space \|= range.end() == offset;
	}
	if let Some(range) = string.close_quote_text_range() {
	cov_mark::hit!(join_string_literal_close_quote);
	no_space \|= range.start()
	== offset
	+ TextSize::of('\n')
	+ TextSize::try_from(n_spaces_after_line_break).unwrap();
	}
	}

	let range = TextRange::at(offset, ((n_spaces_after_line_break + 1) as u32).into());
	let replace_with = if no_space { "" } else { " " };
	edit.replace(range, replace_with.to_owned());
	return;
	}

	// The node is between two other nodes
	let (prev, next) = match (token.prev_sibling_or_token(), token.next_sibling_or_token()) {
	(Some(prev), Some(next)) => (prev, next),
	_ => return,
	};

	if config.remove_trailing_comma && prev.kind() == T![,] {
	match next.kind() {
	T![')'] \| T![']'] => {
	// Removes: trailing comma, newline (incl. surrounding whitespace)
	edit.delete(TextRange::new(prev.text_range().start(), token.text_range().end()));
	return;
	}
	T!['}'] => {
	// Removes: comma, newline (incl. surrounding whitespace)
	let space = match prev.prev_sibling_or_token() {
	Some(left) => compute_ws(left.kind(), next.kind()),
	None => " ",
	};
	edit.replace(
	TextRange::new(prev.text_range().start(), token.text_range().end()),
	space.to_owned(),
	);
	return;
	}
	_ => (),
	}
	}

	if config.join_else_if {
	if let (Some(prev), Some(_next)) = (as_if_expr(&prev), as_if_expr(&next)) {
	match prev.else_token() {
	Some(_) => cov_mark::hit!(join_two_ifs_with_existing_else),
	None => {
	cov_mark::hit!(join_two_ifs);
	edit.replace(token.text_range(), " else ".to_owned());
	return;
	}
	}
	}
	}

	if config.join_assignments && join_assignments(edit, &prev, &next).is_some() {
	return;
	}

	if config.unwrap_trivial_blocks {
	// Special case that turns something like:
	//
	// ```
	// my_function({$0
	// <some-expr>
	// })
	// ```
	//
	// into `my_function(<some-expr>)`
	if join_single_expr_block(edit, token).is_some() {
	return;
	}
	// ditto for
	//
	// ```
	// use foo::{$0
	// bar
	// };
	// ```
	if join_single_use_tree(edit, token).is_some() {
	return;
	}
	}

	if let (Some(_), Some(next)) = (
	prev.as_token().cloned().and_then(ast::Comment::cast),
	next.as_token().cloned().and_then(ast::Comment::cast),
	) {
	// Removes: newline (incl. surrounding whitespace), start of the next comment
	edit.delete(TextRange::new(
	token.text_range().start(),
	next.syntax().text_range().start() + TextSize::of(next.prefix()),
	));
	return;
	}

	// Remove newline but add a computed amount of whitespace characters
	edit.replace(token.text_range(), compute_ws(prev.kind(), next.kind()).to_owned());
	}

	fn join_single_expr_block(edit: &mut TextEditBuilder, token: &SyntaxToken) -> Option<()> {
	let block_expr = ast::BlockExpr::cast(token.parent_ancestors().nth(1)?)?;
	if !block_expr.is_standalone() {
	return None;
	}
	let expr = extract_trivial_expression(&block_expr)?;

	let block_range = block_expr.syntax().text_range();
	let mut buf = expr.syntax().text().to_string();

	// Match block needs to have a comma after the block
	if let Some(match_arm) = block_expr.syntax().parent().and_then(ast::MatchArm::cast) {
	if match_arm.comma_token().is_none() {
	buf.push(',');
	}
	}

	edit.replace(block_range, buf);

	Some(())
	}

	fn join_single_use_tree(edit: &mut TextEditBuilder, token: &SyntaxToken) -> Option<()> {
	let use_tree_list = ast::UseTreeList::cast(token.parent()?)?;
	let (tree,) = use_tree_list.use_trees().collect_tuple()?;
	edit.replace(use_tree_list.syntax().text_range(), tree.syntax().text().to_string());
	Some(())
	}

	fn join_assignments(
	edit: &mut TextEditBuilder,
	prev: &SyntaxElement,
	next: &SyntaxElement,
	) -> Option<()> {
	let let_stmt = ast::LetStmt::cast(prev.as_node()?.clone())?;
	if let_stmt.eq_token().is_some() {
	cov_mark::hit!(join_assignments_already_initialized);
	return None;
	}
	let let_ident_pat = match let_stmt.pat()? {
	ast::Pat::IdentPat(it) => it,
	_ => return None,
	};

	let expr_stmt = ast::ExprStmt::cast(next.as_node()?.clone())?;
	let bin_expr = match expr_stmt.expr()? {
	ast::Expr::BinExpr(it) => it,
	_ => return None,
	};
	if !matches!(bin_expr.op_kind()?, ast::BinaryOp::Assignment { op: None }) {
	return None;
	}
	let lhs = bin_expr.lhs()?;
	let name_ref = expr_as_name_ref(&lhs)?;

	if name_ref.to_string() != let_ident_pat.syntax().to_string() {
	cov_mark::hit!(join_assignments_mismatch);
	return None;
	}

	edit.delete(let_stmt.semicolon_token()?.text_range().cover(lhs.syntax().text_range()));
	Some(())
	}

	fn as_if_expr(element: &SyntaxElement) -> Option<ast::IfExpr> {
	let mut node = element.as_node()?.clone();
	if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
	node = stmt.expr()?.syntax().clone();
	}
	ast::IfExpr::cast(node)
	}

	fn compute_ws(left: SyntaxKind, right: SyntaxKind) -> &'static str {
	match left {
	T!['('] \| T!['['] => return "",
	T!['{'] => {
	if let USE_TREE = right {
	return "";
	}
	}
	_ => (),
	}
	match right {
	T![')'] \| T![']'] => return "",
	T!['}'] => {
	if let USE_TREE = left {
	return "";
	}
	}
	T![.] => return "",
	_ => (),
	}
	" "
	}

	#[cfg(test)]
	mod tests {
	use test_utils::{add_cursor, assert_eq_text, extract_offset, extract_range};

	use super::*;

	fn check_join_lines(ra_fixture_before: &str, ra_fixture_after: &str) {
	let config = JoinLinesConfig {
	join_else_if: true,
	remove_trailing_comma: true,
	unwrap_trivial_blocks: true,
	join_assignments: true,
	};

	let (before_cursor_pos, before) = extract_offset(ra_fixture_before);
	let file = SourceFile::parse(&before, span::Edition::CURRENT).ok().unwrap();

	let range = TextRange::empty(before_cursor_pos);
	let result = join_lines(&config, &file, range);

	let actual = {
	let mut actual = before;
	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);
	assert_eq_text!(ra_fixture_after, &actual);
	}

	fn check_join_lines_sel(ra_fixture_before: &str, ra_fixture_after: &str) {
	let config = JoinLinesConfig {
	join_else_if: true,
	remove_trailing_comma: true,
	unwrap_trivial_blocks: true,
	join_assignments: true,
	};

	let (sel, before) = extract_range(ra_fixture_before);
	let parse = SourceFile::parse(&before, span::Edition::CURRENT);
	let result = join_lines(&config, &parse.tree(), sel);
	let actual = {
	let mut actual = before;
	result.apply(&mut actual);
	actual
	};
	assert_eq_text!(ra_fixture_after, &actual);
	}

	#[test]
	fn test_join_lines_comma() {
	check_join_lines(
	r"
	fn foo() {
	$0foo(1,
	)
	}
	",
	r"
	fn foo() {
	$0foo(1)
	}
	",
	);
	}

	#[test]
	fn test_join_lines_lambda_block() {
	check_join_lines(
	r"
	pub fn reparse(&self, edit: &AtomTextEdit) -> File {
	$0self.incremental_reparse(edit).unwrap_or_else(\|\| {
	self.full_reparse(edit)
	})
	}
	",
	r"
	pub fn reparse(&self, edit: &AtomTextEdit) -> File {
	$0self.incremental_reparse(edit).unwrap_or_else(\|\| self.full_reparse(edit))
	}
	",
	);
	}

	#[test]
	fn test_join_lines_block() {
	check_join_lines(
	r"
	fn foo() {
	foo($0{
	92
	})
	}",
	r"
	fn foo() {
	foo($092)
	}",
	);
	}

	#[test]
	fn test_join_lines_diverging_block() {
	check_join_lines(
	r"
	fn foo() {
	loop {
	match x {
	92 => $0{
	continue;
	}
	}
	}
	}
	",
	r"
	fn foo() {
	loop {
	match x {
	92 => $0continue,
	}
	}
	}
	",
	);
	}

	#[test]
	fn join_lines_adds_comma_for_block_in_match_arm() {
	check_join_lines(
	r"
	fn foo(e: Result<U, V>) {
	match e {
	Ok(u) => $0{
	u.foo()
	}
	Err(v) => v,
	}
	}",
	r"
	fn foo(e: Result<U, V>) {
	match e {
	Ok(u) => $0u.foo(),
	Err(v) => v,
	}
	}",
	);
	}

	#[test]
	fn join_lines_multiline_in_block() {
	check_join_lines(
	r"
	fn foo() {
	match ty {
	$0 Some(ty) => {
	match ty {
	_ => false,
	}
	}
	_ => true,
	}
	}
	",
	r"
	fn foo() {
	match ty {
	$0 Some(ty) => match ty {
	_ => false,
	},
	_ => true,
	}
	}
	",
	);
	}

	#[test]
	fn join_lines_keeps_comma_for_block_in_match_arm() {
	// We already have a comma
	check_join_lines(
	r"
	fn foo(e: Result<U, V>) {
	match e {
	Ok(u) => $0{
	u.foo()
	},
	Err(v) => v,
	}
	}",
	r"
	fn foo(e: Result<U, V>) {
	match e {
	Ok(u) => $0u.foo(),
	Err(v) => v,
	}
	}",
	);

	// comma with whitespace between brace and ,
	check_join_lines(
	r"
	fn foo(e: Result<U, V>) {
	match e {
	Ok(u) => $0{
	u.foo()
	} ,
	Err(v) => v,
	}
	}",
	r"
	fn foo(e: Result<U, V>) {
	match e {
	Ok(u) => $0u.foo() ,
	Err(v) => v,
	}
	}",
	);

	// comma with newline between brace and ,
	check_join_lines(
	r"
	fn foo(e: Result<U, V>) {
	match e {
	Ok(u) => $0{
	u.foo()
	}
	,
	Err(v) => v,
	}
	}",
	r"
	fn foo(e: Result<U, V>) {
	match e {
	Ok(u) => $0u.foo()
	,
	Err(v) => v,
	}
	}",
	);
	}

	#[test]
	fn join_lines_keeps_comma_with_single_arg_tuple() {
	// A single arg tuple
	check_join_lines(
	r"
	fn foo() {
	let x = ($0{
	4
	},);
	}",
	r"
	fn foo() {
	let x = ($04,);
	}",
	);

	// single arg tuple with whitespace between brace and comma
	check_join_lines(
	r"
	fn foo() {
	let x = ($0{
	4
	} ,);
	}",
	r"
	fn foo() {
	let x = ($04 ,);
	}",
	);

	// single arg tuple with newline between brace and comma
	check_join_lines(
	r"
	fn foo() {
	let x = ($0{
	4
	}
	,);
	}",
	r"
	fn foo() {
	let x = ($04
	,);
	}",
	);
	}

	#[test]
	fn test_join_lines_use_items_left() {
	// No space after the '{'
	check_join_lines(
	r"
	$0use syntax::{
	TextSize, TextRange,
	};",
	r"
	$0use syntax::{TextSize, TextRange,
	};",
	);
	}

	#[test]
	fn test_join_lines_use_items_right() {
	// No space after the '}'
	check_join_lines(
	r"
	use syntax::{
	$0 TextSize, TextRange
	};",
	r"
	use syntax::{
	$0 TextSize, TextRange};",
	);
	}

	#[test]
	fn test_join_lines_use_items_right_comma() {
	// No space after the '}'
	check_join_lines(
	r"
	use syntax::{
	$0 TextSize, TextRange,
	};",
	r"
	use syntax::{
	$0 TextSize, TextRange};",
	);
	}

	#[test]
	fn test_join_lines_use_tree() {
	check_join_lines(
	r"
	use syntax::{
	algo::$0{
	find_token_at_offset,
	},
	ast,
	};",
	r"
	use syntax::{
	algo::$0find_token_at_offset,
	ast,
	};",
	);
	}

	#[test]
	fn test_join_lines_normal_comments() {
	check_join_lines(
	r"
	fn foo() {
	// Hello$0
	// world!
	}
	",
	r"
	fn foo() {
	// Hello$0 world!
	}
	",
	);
	}

	#[test]
	fn test_join_lines_doc_comments() {
	check_join_lines(
	r"
	fn foo() {
	/// Hello$0
	/// world!
	}
	",
	r"
	fn foo() {
	/// Hello$0 world!
	}
	",
	);
	}

	#[test]
	fn test_join_lines_mod_comments() {
	check_join_lines(
	r"
	fn foo() {
	//! Hello$0
	//! world!
	}
	",
	r"
	fn foo() {
	//! Hello$0 world!
	}
	",
	);
	}

	#[test]
	fn test_join_lines_multiline_comments_1() {
	check_join_lines(
	r"
	fn foo() {
	// Hello$0
	/* world! */
	}
	",
	r"
	fn foo() {
	// Hello$0 world! */
	}
	",
	);
	}

	#[test]
	fn test_join_lines_multiline_comments_2() {
	check_join_lines(
	r"
	fn foo() {
	// The$0
	/* quick
	brown
	fox! */
	}
	",
	r"
	fn foo() {
	// The$0 quick
	brown
	fox! */
	}
	",
	);
	}

	#[test]
	fn test_join_lines_selection_fn_args() {
	check_join_lines_sel(
	r"
	fn foo() {
	$0foo(1,
	2,
	3,
	$0)
	}
	",
	r"
	fn foo() {
	foo(1, 2, 3)
	}
	",
	);
	}

	#[test]
	fn test_join_lines_selection_struct() {
	check_join_lines_sel(
	r"
	struct Foo $0{
	f: u32,
	}$0
	",
	r"
	struct Foo { f: u32 }
	",
	);
	}

	#[test]
	fn test_join_lines_selection_dot_chain() {
	check_join_lines_sel(
	r"
	fn foo() {
	join($0type_params.type_params()
	.filter_map(\|it\| it.name())
	.map(\|it\| it.text())$0)
	}",
	r"
	fn foo() {
	join(type_params.type_params().filter_map(\|it\| it.name()).map(\|it\| it.text()))
	}",
	);
	}

	#[test]
	fn test_join_lines_selection_lambda_block_body() {
	check_join_lines_sel(
	r"
	pub fn handle_find_matching_brace() {
	params.offsets
	.map(\|offset\| $0{
	world.analysis().matching_brace(&file, offset).unwrap_or(offset)
	}$0)
	.collect();
	}",
	r"
	pub fn handle_find_matching_brace() {
	params.offsets
	.map(\|offset\| world.analysis().matching_brace(&file, offset).unwrap_or(offset))
	.collect();
	}",
	);
	}

	#[test]
	fn test_join_lines_commented_block() {
	check_join_lines(
	r"
	fn main() {
	let _ = {
	// $0foo
	// bar
	92
	};
	}
	",
	r"
	fn main() {
	let _ = {
	// $0foo bar
	92
	};
	}
	",
	)
	}

	#[test]
	fn join_lines_mandatory_blocks_block() {
	check_join_lines(
	r"
	$0fn foo() {
	92
	}
	",
	r"
	$0fn foo() { 92
	}
	",
	);

	check_join_lines(
	r"
	fn foo() {
	$0if true {
	92
	}
	}
	",
	r"
	fn foo() {
	$0if true { 92
	}
	}
	",
	);

	check_join_lines(
	r"
	fn foo() {
	$0loop {
	92
	}
	}
	",
	r"
	fn foo() {
	$0loop { 92
	}
	}
	",
	);

	check_join_lines(
	r"
	fn foo() {
	$0unsafe {
	92
	}
	}
	",
	r"
	fn foo() {
	$0unsafe { 92
	}
	}
	",
	);
	}

	#[test]
	fn join_string_literal() {
	{
	cov_mark::check!(join_string_literal_open_quote);
	check_join_lines(
	r#"
	fn main() {
	$0"
	hello
	";
	}
	"#,
	r#"
	fn main() {
	$0"hello
	";
	}
	"#,
	);
	}

	{
	cov_mark::check!(join_string_literal_close_quote);
	check_join_lines(
	r#"
	fn main() {
	$0"hello
	";
	}
	"#,
	r#"
	fn main() {
	$0"hello";
	}
	"#,
	);
	check_join_lines(
	r#"
	fn main() {
	$0r"hello
	";
	}
	"#,
	r#"
	fn main() {
	$0r"hello";
	}
	"#,
	);
	}

	check_join_lines(
	r#"
	fn main() {
	"
	$0hello
	world
	";
	}
	"#,
	r#"
	fn main() {
	"
	$0hello world
	";
	}
	"#,
	);
	}

	#[test]
	fn join_last_line_empty() {
	check_join_lines(
	r#"
	fn main() {$0}
	"#,
	r#"
	fn main() {$0}
	"#,
	);
	}

	#[test]
	fn join_two_ifs() {
	cov_mark::check!(join_two_ifs);
	check_join_lines(
	r#"
	fn main() {
	if foo {

	}$0
	if bar {

	}
	}
	"#,
	r#"
	fn main() {
	if foo {

	}$0 else if bar {

	}
	}
	"#,
	);
	}

	#[test]
	fn join_two_ifs_with_existing_else() {
	cov_mark::check!(join_two_ifs_with_existing_else);
	check_join_lines(
	r#"
	fn main() {
	if foo {

	} else {

	}$0
	if bar {

	}
	}
	"#,
	r#"
	fn main() {
	if foo {

	} else {

	}$0 if bar {

	}
	}
	"#,
	);
	}

	#[test]
	fn join_assignments() {
	check_join_lines(
	r#"
	fn foo() {
	$0let foo;
	foo = "bar";
	}
	"#,
	r#"
	fn foo() {
	$0let foo = "bar";
	}
	"#,
	);

	cov_mark::check!(join_assignments_mismatch);
	check_join_lines(
	r#"
	fn foo() {
	let foo;
	let qux;$0
	foo = "bar";
	}
	"#,
	r#"
	fn foo() {
	let foo;
	let qux;$0 foo = "bar";
	}
	"#,
	);

	cov_mark::check!(join_assignments_already_initialized);
	check_join_lines(
	r#"
	fn foo() {
	let foo = "bar";$0
	foo = "bar";
	}
	"#,
	r#"
	fn foo() {
	let foo = "bar";$0 foo = "bar";
	}
	"#,
	);
	}
	}