1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use std::cmp::{min, Ordering};
14 use std::iter::{repeat, ExactSizeIterator};
16 use syntax::{ast, ptr};
17 use syntax::codemap::{BytePos, CodeMap, Span};
18 use syntax::parse::classify;
20 use {Indent, Shape, Spanned};
21 use chains::rewrite_chain;
22 use codemap::{LineRangeUtils, SpanUtils};
23 use comment::{combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
24 rewrite_comment, rewrite_missing_comment, FindUncommented};
25 use config::{Config, ControlBraceStyle, IndentStyle, MultilineStyle, Style};
26 use items::{span_hi_for_arg, span_lo_for_arg};
27 use lists::{definitive_tactic, itemize_list, shape_for_tactic, struct_lit_formatting,
28 struct_lit_shape, struct_lit_tactic, write_list, DefinitiveListTactic, ListFormatting,
29 ListItem, ListTactic, Separator, SeparatorPlace, SeparatorTactic};
30 use macros::{rewrite_macro, MacroArg, MacroPosition};
31 use patterns::{can_be_overflowed_pat, TuplePatField};
32 use rewrite::{Rewrite, RewriteContext};
33 use string::{rewrite_string, StringFormat};
34 use types::{can_be_overflowed_type, rewrite_path, PathContext};
35 use utils::{colon_spaces, contains_skip, extra_offset, first_line_width, inner_attributes,
36 last_line_extendable, last_line_width, left_most_sub_expr, mk_sp, outer_attributes,
37 paren_overhead, ptr_vec_to_ref_vec, semicolon_for_stmt, stmt_expr,
38 trimmed_last_line_width, wrap_str};
39 use vertical::rewrite_with_alignment;
40 use visitor::FmtVisitor;
42 impl Rewrite for ast::Expr {
43 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
44 format_expr(self, ExprType::SubExpression, context, shape)
48 #[derive(Copy, Clone, PartialEq)]
57 context: &RewriteContext,
60 skip_out_of_file_lines_range!(context, expr.span);
62 if contains_skip(&*expr.attrs) {
63 return Some(context.snippet(expr.span()));
66 let expr_rw = match expr.node {
67 ast::ExprKind::Array(ref expr_vec) => rewrite_array(
68 expr_vec.iter().map(|e| &**e),
69 mk_sp(context.codemap.span_after(expr.span, "["), expr.span.hi()),
74 ast::ExprKind::Lit(ref l) => match l.node {
75 ast::LitKind::Str(_, ast::StrStyle::Cooked) => {
76 rewrite_string_lit(context, l.span, shape)
79 context.snippet(expr.span),
80 context.config.max_width(),
84 ast::ExprKind::Call(ref callee, ref args) => {
85 let inner_span = mk_sp(callee.span.hi(), expr.span.hi());
86 let callee_str = try_opt!(callee.rewrite(context, shape));
87 rewrite_call(context, &callee_str, &args, inner_span, shape)
89 ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape),
90 ast::ExprKind::Binary(ref op, ref lhs, ref rhs) => {
91 // FIXME: format comments between operands and operator
96 &format!(" {} ", context.snippet(op.span)),
100 context.config.binop_separator(),
103 ast::ExprKind::Unary(ref op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape),
104 ast::ExprKind::Struct(ref path, ref fields, ref base) => rewrite_struct_lit(
108 base.as_ref().map(|e| &**e),
112 ast::ExprKind::Tup(ref items) => {
113 rewrite_tuple(context, &ptr_vec_to_ref_vec(&items), expr.span, shape)
115 ast::ExprKind::If(..) |
116 ast::ExprKind::IfLet(..) |
117 ast::ExprKind::ForLoop(..) |
118 ast::ExprKind::Loop(..) |
119 ast::ExprKind::While(..) |
120 ast::ExprKind::WhileLet(..) => to_control_flow(expr, expr_type)
121 .and_then(|control_flow| control_flow.rewrite(context, shape)),
122 ast::ExprKind::Block(ref block) => {
124 ExprType::Statement => {
125 if is_unsafe_block(block) {
126 block.rewrite(context, shape)
127 } else if let rw @ Some(_) = rewrite_empty_block(context, block, shape) {
128 // Rewrite block without trying to put it in a single line.
131 let prefix = try_opt!(block_prefix(context, block, shape));
132 rewrite_block_with_visitor(context, &prefix, block, shape)
135 ExprType::SubExpression => block.rewrite(context, shape),
138 ast::ExprKind::Match(ref cond, ref arms) => {
139 rewrite_match(context, cond, arms, shape, expr.span, &expr.attrs)
141 ast::ExprKind::Path(ref qself, ref path) => {
142 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
144 ast::ExprKind::Assign(ref lhs, ref rhs) => {
145 rewrite_assignment(context, lhs, rhs, None, shape)
147 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
148 rewrite_assignment(context, lhs, rhs, Some(op), shape)
150 ast::ExprKind::Continue(ref opt_ident) => {
151 let id_str = match *opt_ident {
152 Some(ident) => format!(" {}", ident.node),
153 None => String::new(),
156 format!("continue{}", id_str),
157 context.config.max_width(),
161 ast::ExprKind::Break(ref opt_ident, ref opt_expr) => {
162 let id_str = match *opt_ident {
163 Some(ident) => format!(" {}", ident.node),
164 None => String::new(),
167 if let Some(ref expr) = *opt_expr {
168 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
171 format!("break{}", id_str),
172 context.config.max_width(),
177 ast::ExprKind::Yield(ref opt_expr) => if let Some(ref expr) = *opt_expr {
178 rewrite_unary_prefix(context, "yield ", &**expr, shape)
180 wrap_str("yield".to_string(), context.config.max_width(), shape)
182 ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) => {
183 rewrite_closure(capture, fn_decl, body, expr.span, context, shape)
185 ast::ExprKind::Try(..) |
186 ast::ExprKind::Field(..) |
187 ast::ExprKind::TupField(..) |
188 ast::ExprKind::MethodCall(..) => rewrite_chain(expr, context, shape),
189 ast::ExprKind::Mac(ref mac) => {
190 // Failure to rewrite a marco should not imply failure to
191 // rewrite the expression.
192 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
194 context.snippet(expr.span),
195 context.config.max_width(),
200 ast::ExprKind::Ret(None) => {
201 wrap_str("return".to_owned(), context.config.max_width(), shape)
203 ast::ExprKind::Ret(Some(ref expr)) => {
204 rewrite_unary_prefix(context, "return ", &**expr, shape)
206 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
207 ast::ExprKind::AddrOf(mutability, ref expr) => {
208 rewrite_expr_addrof(context, mutability, expr, shape)
210 ast::ExprKind::Cast(ref expr, ref ty) => rewrite_pair(
218 SeparatorPlace::Front,
220 ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
228 SeparatorPlace::Back,
230 ast::ExprKind::Index(ref expr, ref index) => {
231 rewrite_index(&**expr, &**index, context, shape)
233 ast::ExprKind::Repeat(ref expr, ref repeats) => {
234 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
247 SeparatorPlace::Back,
250 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
251 let delim = match limits {
252 ast::RangeLimits::HalfOpen => "..",
253 ast::RangeLimits::Closed => "...",
256 fn needs_space_before_range(context: &RewriteContext, lhs: &ast::Expr) -> bool {
258 ast::ExprKind::Lit(ref lit) => match lit.node {
259 ast::LitKind::FloatUnsuffixed(..) => {
260 context.snippet(lit.span).ends_with('.')
268 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
269 (Some(lhs), Some(rhs)) => {
270 let sp_delim = if context.config.spaces_around_ranges() {
271 format!(" {} ", delim)
272 } else if needs_space_before_range(context, lhs) {
273 format!(" {}", delim)
285 SeparatorPlace::Front,
288 (None, Some(rhs)) => {
289 let sp_delim = if context.config.spaces_around_ranges() {
290 format!("{} ", delim)
294 rewrite_unary_prefix(context, &sp_delim, &*rhs, shape)
296 (Some(lhs), None) => {
297 let sp_delim = if context.config.spaces_around_ranges() {
298 format!(" {}", delim)
302 rewrite_unary_suffix(context, &sp_delim, &*lhs, shape)
304 (None, None) => wrap_str(delim.into(), context.config.max_width(), shape),
307 // We do not format these expressions yet, but they should still
308 // satisfy our width restrictions.
309 ast::ExprKind::InPlace(..) | ast::ExprKind::InlineAsm(..) => wrap_str(
310 context.snippet(expr.span),
311 context.config.max_width(),
314 ast::ExprKind::Catch(ref block) => {
315 if let rw @ Some(_) = rewrite_single_line_block(context, "do catch ", block, shape) {
319 let budget = shape.width.checked_sub(9).unwrap_or(0);
323 try_opt!(block.rewrite(context, Shape::legacy(budget, shape.indent)))
330 .and_then(|expr_str| {
331 recover_comment_removed(expr_str, expr.span, context, shape)
333 .and_then(|expr_str| {
334 let attrs = outer_attributes(&expr.attrs);
335 let attrs_str = try_opt!(attrs.rewrite(context, shape));
337 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
340 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
344 pub fn rewrite_pair<LHS, RHS>(
350 context: &RewriteContext,
352 separator_place: SeparatorPlace,
358 let lhs_overhead = match separator_place {
359 SeparatorPlace::Back => shape.used_width() + prefix.len() + infix.trim_right().len(),
360 SeparatorPlace::Front => shape.used_width(),
362 let lhs_shape = Shape {
363 width: context.budget(lhs_overhead),
366 let lhs_result = try_opt!(
367 lhs.rewrite(context, lhs_shape)
368 .map(|lhs_str| format!("{}{}", prefix, lhs_str))
371 // Try to the both lhs and rhs on the same line.
372 let rhs_orig_result = shape
373 .offset_left(last_line_width(&lhs_result) + infix.len())
374 .and_then(|s| s.sub_width(suffix.len()))
375 .and_then(|rhs_shape| rhs.rewrite(context, rhs_shape));
376 if let Some(ref rhs_result) = rhs_orig_result {
377 // If the rhs looks like block expression, we allow it to stay on the same line
378 // with the lhs even if it is multi-lined.
379 let allow_same_line = rhs_result
382 .map(|first_line| first_line.ends_with('{'))
384 if !rhs_result.contains('\n') || allow_same_line {
385 return Some(format!("{}{}{}{}", lhs_result, infix, rhs_result, suffix));
389 // We have to use multiple lines.
390 // Re-evaluate the rhs because we have more space now:
391 let mut rhs_shape = try_opt!(match context.config.control_style() {
392 Style::Legacy => shape
393 .sub_width(suffix.len() + prefix.len())
394 .map(|s| s.visual_indent(prefix.len())),
396 // Try to calculate the initial constraint on the right hand side.
397 let rhs_overhead = shape.rhs_overhead(context.config);
398 Shape::indented(shape.indent.block_indent(context.config), context.config)
399 .sub_width(rhs_overhead)
402 let infix = match separator_place {
403 SeparatorPlace::Back => infix.trim_right(),
404 SeparatorPlace::Front => infix.trim_left(),
406 if separator_place == SeparatorPlace::Front {
407 rhs_shape = try_opt!(rhs_shape.offset_left(infix.len()));
409 let rhs_result = try_opt!(rhs.rewrite(context, rhs_shape));
410 match separator_place {
411 SeparatorPlace::Back => Some(format!(
415 rhs_shape.indent.to_string(context.config),
419 SeparatorPlace::Front => Some(format!(
422 rhs_shape.indent.to_string(context.config),
430 pub fn rewrite_array<'a, I>(
433 context: &RewriteContext,
435 trailing_comma: bool,
438 I: Iterator<Item = &'a ast::Expr>,
440 let bracket_size = if context.config.spaces_within_square_brackets() {
446 let nested_shape = match context.config.array_layout() {
447 IndentStyle::Block => try_opt!(
450 .block_indent(context.config.tab_spaces())
451 .with_max_width(context.config)
454 IndentStyle::Visual => try_opt!(
456 .visual_indent(bracket_size)
457 .sub_width(bracket_size * 2)
461 let items = itemize_list(
465 |item| item.span.lo(),
466 |item| item.span.hi(),
467 |item| item.rewrite(context, nested_shape),
471 ).collect::<Vec<_>>();
473 if items.is_empty() {
474 if context.config.spaces_within_square_brackets() {
475 return Some("[ ]".to_string());
477 return Some("[]".to_string());
481 let has_long_item = items
483 .any(|li| li.item.as_ref().map(|s| s.len() > 10).unwrap_or(false));
485 let mut tactic = match context.config.array_layout() {
486 IndentStyle::Block => {
487 // FIXME wrong shape in one-line case
488 match shape.width.checked_sub(2 * bracket_size) {
491 ListTactic::LimitedHorizontalVertical(context.config.array_width());
492 definitive_tactic(&items, tactic, Separator::Comma, width)
494 None => DefinitiveListTactic::Vertical,
497 IndentStyle::Visual => if has_long_item || items.iter().any(ListItem::is_multiline) {
500 ListTactic::LimitedHorizontalVertical(context.config.array_width()),
505 DefinitiveListTactic::Mixed
508 let ends_with_newline = tactic.ends_with_newline(context.config.array_layout());
509 if context.config.array_horizontal_layout_threshold() > 0
510 && items.len() > context.config.array_horizontal_layout_threshold()
512 tactic = DefinitiveListTactic::Mixed;
515 let fmt = ListFormatting {
518 trailing_separator: if trailing_comma {
519 SeparatorTactic::Always
520 } else if context.inside_macro || context.config.array_layout() == IndentStyle::Visual {
521 SeparatorTactic::Never
523 SeparatorTactic::Vertical
525 separator_place: SeparatorPlace::Back,
527 ends_with_newline: ends_with_newline,
528 preserve_newline: false,
529 config: context.config,
531 let list_str = try_opt!(write_list(&items, &fmt));
533 let result = if context.config.array_layout() == IndentStyle::Visual
534 || tactic == DefinitiveListTactic::Horizontal
536 if context.config.spaces_within_square_brackets() && !list_str.is_empty() {
537 format!("[ {} ]", list_str)
539 format!("[{}]", list_str)
544 nested_shape.indent.to_string(context.config),
546 shape.block().indent.to_string(context.config)
553 // Return type is (prefix, extra_offset)
554 fn rewrite_closure_fn_decl(
555 capture: ast::CaptureBy,
556 fn_decl: &ast::FnDecl,
559 context: &RewriteContext,
561 ) -> Option<(String, usize)> {
562 let mover = if capture == ast::CaptureBy::Value {
567 // 4 = "|| {".len(), which is overconservative when the closure consists of
568 // a single expression.
569 let nested_shape = try_opt!(try_opt!(shape.shrink_left(mover.len())).sub_width(4));
572 let argument_offset = nested_shape.indent + 1;
573 let arg_shape = try_opt!(nested_shape.offset_left(1)).visual_indent(0);
574 let ret_str = try_opt!(fn_decl.output.rewrite(context, arg_shape));
576 let arg_items = itemize_list(
578 fn_decl.inputs.iter(),
580 |arg| span_lo_for_arg(arg),
581 |arg| span_hi_for_arg(context, arg),
582 |arg| arg.rewrite(context, arg_shape),
583 context.codemap.span_after(span, "|"),
587 let item_vec = arg_items.collect::<Vec<_>>();
588 // 1 = space between arguments and return type.
589 let horizontal_budget = nested_shape
591 .checked_sub(ret_str.len() + 1)
593 let tactic = definitive_tactic(
595 ListTactic::HorizontalVertical,
599 let arg_shape = match tactic {
600 DefinitiveListTactic::Horizontal => try_opt!(arg_shape.sub_width(ret_str.len() + 1)),
604 let fmt = ListFormatting {
607 trailing_separator: SeparatorTactic::Never,
608 separator_place: SeparatorPlace::Back,
610 ends_with_newline: false,
611 preserve_newline: true,
612 config: context.config,
614 let list_str = try_opt!(write_list(&item_vec, &fmt));
615 let mut prefix = format!("{}|{}|", mover, list_str);
616 // 1 = space between `|...|` and body.
617 let extra_offset = extra_offset(&prefix, shape) + 1;
619 if !ret_str.is_empty() {
620 if prefix.contains('\n') {
622 prefix.push_str(&argument_offset.to_string(context.config));
626 prefix.push_str(&ret_str);
629 Some((prefix, extra_offset))
632 // This functions is pretty messy because of the rules around closures and blocks:
633 // FIXME - the below is probably no longer true in full.
634 // * if there is a return type, then there must be braces,
635 // * given a closure with braces, whether that is parsed to give an inner block
636 // or not depends on if there is a return type and if there are statements
638 // * if the first expression in the body ends with a block (i.e., is a
639 // statement without needing a semi-colon), then adding or removing braces
640 // can change whether it is treated as an expression or statement.
642 capture: ast::CaptureBy,
643 fn_decl: &ast::FnDecl,
646 context: &RewriteContext,
648 ) -> Option<String> {
649 let (prefix, extra_offset) = try_opt!(rewrite_closure_fn_decl(
657 // 1 = space between `|...|` and body.
658 let body_shape = try_opt!(shape.offset_left(extra_offset));
660 if let ast::ExprKind::Block(ref block) = body.node {
661 // The body of the closure is an empty block.
662 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) {
663 return Some(format!("{} {{}}", prefix));
666 // Figure out if the block is necessary.
667 let needs_block = block.rules != ast::BlockCheckMode::Default || block.stmts.len() > 1
668 || context.inside_macro
669 || block_contains_comment(block, context.codemap)
670 || prefix.contains('\n');
672 let no_return_type = if let ast::FunctionRetTy::Default(_) = fn_decl.output {
677 if no_return_type && !needs_block {
678 // block.stmts.len() == 1
679 if let Some(expr) = stmt_expr(&block.stmts[0]) {
680 if let Some(rw) = rewrite_closure_expr(expr, &prefix, context, body_shape) {
686 // Either we require a block, or tried without and failed.
687 rewrite_closure_block(block, &prefix, context, body_shape)
689 rewrite_closure_expr(body, &prefix, context, body_shape).or_else(|| {
690 // The closure originally had a non-block expression, but we can't fit on
691 // one line, so we'll insert a block.
692 rewrite_closure_with_block(context, body_shape, &prefix, body)
697 // Rewrite closure with a single expression wrapping its body with block.
698 fn rewrite_closure_with_block(
699 context: &RewriteContext,
703 ) -> Option<String> {
704 let block = ast::Block {
707 id: ast::NodeId::new(0),
708 node: ast::StmtKind::Expr(ptr::P(body.clone())),
712 id: ast::NodeId::new(0),
713 rules: ast::BlockCheckMode::Default,
716 rewrite_closure_block(&block, prefix, context, shape)
719 // Rewrite closure with a single expression without wrapping its body with block.
720 fn rewrite_closure_expr(
723 context: &RewriteContext,
725 ) -> Option<String> {
726 let mut rewrite = expr.rewrite(context, shape);
727 if classify::expr_requires_semi_to_be_stmt(left_most_sub_expr(expr)) {
728 rewrite = and_one_line(rewrite);
730 rewrite = rewrite.and_then(|rw| {
731 if context.config.multiline_closure_forces_block() && rw.contains('\n') {
737 rewrite.map(|rw| format!("{} {}", prefix, rw))
740 // Rewrite closure whose body is block.
741 fn rewrite_closure_block(
744 context: &RewriteContext,
746 ) -> Option<String> {
747 // Start with visual indent, then fall back to block indent if the
749 let block_threshold = context.config.closure_block_indent_threshold();
750 if block_threshold >= 0 {
751 if let Some(block_str) = block.rewrite(context, shape) {
752 if block_str.matches('\n').count() <= block_threshold as usize
753 && !need_block_indent(&block_str, shape)
755 if let Some(block_str) = block_str.rewrite(context, shape) {
756 return Some(format!("{} {}", prefix, block_str));
762 // The body of the closure is big enough to be block indented, that
763 // means we must re-format.
764 let block_shape = shape.block();
765 let block_str = try_opt!(block.rewrite(context, block_shape));
766 Some(format!("{} {}", prefix, block_str))
769 fn and_one_line(x: Option<String>) -> Option<String> {
770 x.and_then(|x| if x.contains('\n') { None } else { Some(x) })
773 fn nop_block_collapse(block_str: Option<String>, budget: usize) -> Option<String> {
774 debug!("nop_block_collapse {:?} {}", block_str, budget);
775 block_str.map(|block_str| {
776 if block_str.starts_with('{') && budget >= 2
777 && (block_str[1..].find(|c: char| !c.is_whitespace()).unwrap() == block_str.len() - 2)
786 fn rewrite_empty_block(
787 context: &RewriteContext,
790 ) -> Option<String> {
791 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) && shape.width >= 2
793 return Some("{}".to_owned());
796 // If a block contains only a single-line comment, then leave it on one line.
797 let user_str = context.snippet(block.span);
798 let user_str = user_str.trim();
799 if user_str.starts_with('{') && user_str.ends_with('}') {
800 let comment_str = user_str[1..user_str.len() - 1].trim();
801 if block.stmts.is_empty() && !comment_str.contains('\n') && !comment_str.starts_with("//")
802 && comment_str.len() + 4 <= shape.width
804 return Some(format!("{{ {} }}", comment_str));
811 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
812 Some(match block.rules {
813 ast::BlockCheckMode::Unsafe(..) => {
814 let snippet = context.snippet(block.span);
815 let open_pos = try_opt!(snippet.find_uncommented("{"));
816 // Extract comment between unsafe and block start.
817 let trimmed = &snippet[6..open_pos].trim();
819 if !trimmed.is_empty() {
820 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
821 let budget = try_opt!(shape.width.checked_sub(9));
824 try_opt!(rewrite_comment(
827 Shape::legacy(budget, shape.indent + 7),
835 ast::BlockCheckMode::Default => String::new(),
839 fn rewrite_single_line_block(
840 context: &RewriteContext,
844 ) -> Option<String> {
845 if is_simple_block(block, context.codemap) {
846 let expr_shape = Shape::legacy(shape.width - prefix.len(), shape.indent);
847 let expr_str = try_opt!(block.stmts[0].rewrite(context, expr_shape));
848 let result = format!("{}{{ {} }}", prefix, expr_str);
849 if result.len() <= shape.width && !result.contains('\n') {
856 fn rewrite_block_with_visitor(
857 context: &RewriteContext,
861 ) -> Option<String> {
862 if let rw @ Some(_) = rewrite_empty_block(context, block, shape) {
866 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
867 visitor.block_indent = shape.indent;
868 visitor.is_if_else_block = context.is_if_else_block;
870 ast::BlockCheckMode::Unsafe(..) => {
871 let snippet = context.snippet(block.span);
872 let open_pos = try_opt!(snippet.find_uncommented("{"));
873 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
875 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
878 visitor.visit_block(block, None);
879 Some(format!("{}{}", prefix, visitor.buffer))
882 impl Rewrite for ast::Block {
883 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
884 // shape.width is used only for the single line case: either the empty block `{}`,
885 // or an unsafe expression `unsafe { e }`.
886 if let rw @ Some(_) = rewrite_empty_block(context, self, shape) {
890 let prefix = try_opt!(block_prefix(context, self, shape));
892 let result = rewrite_block_with_visitor(context, &prefix, self, shape);
893 if let Some(ref result_str) = result {
894 if result_str.lines().count() <= 3 {
895 if let rw @ Some(_) = rewrite_single_line_block(context, &prefix, self, shape) {
905 impl Rewrite for ast::Stmt {
906 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
907 skip_out_of_file_lines_range!(context, self.span());
909 let result = match self.node {
910 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
911 ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
912 let suffix = if semicolon_for_stmt(context, self) {
918 let shape = try_opt!(shape.sub_width(suffix.len()));
919 format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
921 ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
923 result.and_then(|res| {
924 recover_comment_removed(res, self.span(), context, shape)
929 // Rewrite condition if the given expression has one.
930 fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
932 ast::ExprKind::Match(ref cond, _) => {
934 let cond_shape = match context.config.control_style() {
935 Style::Legacy => try_opt!(shape.shrink_left(6).and_then(|s| s.sub_width(2))),
936 Style::Rfc => try_opt!(shape.offset_left(8)),
938 cond.rewrite(context, cond_shape)
940 ast::ExprKind::Block(ref block) if block.stmts.len() == 1 => {
941 stmt_expr(&block.stmts[0]).and_then(|e| rewrite_cond(context, e, shape))
943 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
945 String::from("\n") + &shape.indent.block_only().to_string(context.config);
947 .rewrite_cond(context, shape, &alt_block_sep)
948 .and_then(|rw| Some(rw.0))
953 // Abstraction over control flow expressions
955 struct ControlFlow<'a> {
956 cond: Option<&'a ast::Expr>,
957 block: &'a ast::Block,
958 else_block: Option<&'a ast::Expr>,
959 label: Option<ast::SpannedIdent>,
960 pat: Option<&'a ast::Pat>,
964 allow_single_line: bool,
965 // True if this is an `if` expression in an `else if` :-( hacky
970 fn to_control_flow<'a>(expr: &'a ast::Expr, expr_type: ExprType) -> Option<ControlFlow<'a>> {
972 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
976 else_block.as_ref().map(|e| &**e),
977 expr_type == ExprType::SubExpression,
981 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
982 Some(ControlFlow::new_if(
986 else_block.as_ref().map(|e| &**e),
987 expr_type == ExprType::SubExpression,
992 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
993 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
995 ast::ExprKind::Loop(ref block, label) => {
996 Some(ControlFlow::new_loop(block, label, expr.span))
998 ast::ExprKind::While(ref cond, ref block, label) => {
999 Some(ControlFlow::new_while(None, cond, block, label, expr.span))
1001 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
1002 ControlFlow::new_while(Some(pat), cond, block, label, expr.span),
1008 impl<'a> ControlFlow<'a> {
1010 cond: &'a ast::Expr,
1011 pat: Option<&'a ast::Pat>,
1012 block: &'a ast::Block,
1013 else_block: Option<&'a ast::Expr>,
1014 allow_single_line: bool,
1017 ) -> ControlFlow<'a> {
1021 else_block: else_block,
1025 matcher: match pat {
1030 allow_single_line: allow_single_line,
1031 nested_if: nested_if,
1037 block: &'a ast::Block,
1038 label: Option<ast::SpannedIdent>,
1040 ) -> ControlFlow<'a> {
1050 allow_single_line: false,
1057 pat: Option<&'a ast::Pat>,
1058 cond: &'a ast::Expr,
1059 block: &'a ast::Block,
1060 label: Option<ast::SpannedIdent>,
1062 ) -> ControlFlow<'a> {
1070 matcher: match pat {
1075 allow_single_line: false,
1083 cond: &'a ast::Expr,
1084 block: &'a ast::Block,
1085 label: Option<ast::SpannedIdent>,
1087 ) -> ControlFlow<'a> {
1097 allow_single_line: false,
1103 fn rewrite_single_line(
1106 context: &RewriteContext,
1108 ) -> Option<String> {
1109 assert!(self.allow_single_line);
1110 let else_block = try_opt!(self.else_block);
1111 let fixed_cost = self.keyword.len() + " { } else { }".len();
1113 if let ast::ExprKind::Block(ref else_node) = else_block.node {
1114 if !is_simple_block(self.block, context.codemap)
1115 || !is_simple_block(else_node, context.codemap)
1116 || pat_expr_str.contains('\n')
1121 let new_width = try_opt!(width.checked_sub(pat_expr_str.len() + fixed_cost));
1122 let expr = &self.block.stmts[0];
1123 let if_str = try_opt!(expr.rewrite(context, Shape::legacy(new_width, Indent::empty())));
1125 let new_width = try_opt!(new_width.checked_sub(if_str.len()));
1126 let else_expr = &else_node.stmts[0];
1128 try_opt!(else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty())));
1130 if if_str.contains('\n') || else_str.contains('\n') {
1134 let result = format!(
1135 "{} {} {{ {} }} else {{ {} }}",
1142 if result.len() <= width {
1143 return Some(result);
1151 impl<'a> ControlFlow<'a> {
1154 context: &RewriteContext,
1156 alt_block_sep: &str,
1157 ) -> Option<(String, usize)> {
1158 // Do not take the rhs overhead from the upper expressions into account
1159 // when rewriting pattern.
1160 let new_width = context
1163 .checked_sub(shape.used_width())
1165 let fresh_shape = Shape {
1169 let constr_shape = if self.nested_if {
1170 // We are part of an if-elseif-else chain. Our constraints are tightened.
1171 // 7 = "} else " .len()
1172 try_opt!(fresh_shape.offset_left(7))
1177 let label_string = rewrite_label(self.label);
1178 // 1 = space after keyword.
1179 let offset = self.keyword.len() + label_string.len() + 1;
1181 let pat_expr_string = match self.cond {
1183 let cond_shape = match context.config.control_style() {
1184 Style::Legacy => try_opt!(constr_shape.shrink_left(offset)),
1185 Style::Rfc => try_opt!(constr_shape.offset_left(offset)),
1187 try_opt!(rewrite_pat_expr(
1197 None => String::new(),
1200 let brace_overhead =
1201 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
1207 let one_line_budget = context
1210 .checked_sub(constr_shape.used_width() + offset + brace_overhead)
1212 let force_newline_brace = context.config.control_style() == Style::Rfc
1213 && (pat_expr_string.contains('\n') || pat_expr_string.len() > one_line_budget)
1214 && !last_line_extendable(&pat_expr_string);
1216 // Try to format if-else on single line.
1217 if self.allow_single_line && context.config.single_line_if_else_max_width() > 0 {
1218 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
1220 if let Some(cond_str) = trial {
1221 if cond_str.len() <= context.config.single_line_if_else_max_width() {
1222 return Some((cond_str, 0));
1227 let cond_span = if let Some(cond) = self.cond {
1230 mk_sp(self.block.span.lo(), self.block.span.lo())
1233 // `for event in event`
1234 // Do not include label in the span.
1235 let lo = self.label.map_or(self.span.lo(), |label| label.span.hi());
1236 let between_kwd_cond = mk_sp(
1239 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
1241 .map_or(cond_span.lo(), |p| if self.matcher.is_empty() {
1244 context.codemap.span_before(self.span, self.matcher.trim())
1248 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
1250 let after_cond_comment =
1251 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
1253 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
1255 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
1256 || force_newline_brace
1263 let used_width = if pat_expr_string.contains('\n') {
1264 last_line_width(&pat_expr_string)
1266 // 2 = spaces after keyword and condition.
1267 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
1275 between_kwd_cond_comment.as_ref().map_or(
1276 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
1284 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
1291 impl<'a> Rewrite for ControlFlow<'a> {
1292 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1293 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
1296 String::from("\n") + &shape.indent.block_only().to_string(context.config);
1297 let (cond_str, used_width) = try_opt!(self.rewrite_cond(context, shape, &alt_block_sep));
1298 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
1299 if used_width == 0 {
1300 return Some(cond_str);
1303 let block_width = shape.width.checked_sub(used_width).unwrap_or(0);
1304 // This is used only for the empty block case: `{}`. So, we use 1 if we know
1305 // we should avoid the single line case.
1306 let block_width = if self.else_block.is_some() || self.nested_if {
1311 let block_shape = Shape {
1315 let mut block_context = context.clone();
1316 block_context.is_if_else_block = self.else_block.is_some();
1317 let block_str = try_opt!(rewrite_block_with_visitor(
1324 let mut result = format!("{}{}", cond_str, block_str);
1326 if let Some(else_block) = self.else_block {
1327 let shape = Shape::indented(shape.indent, context.config);
1328 let mut last_in_chain = false;
1329 let rewrite = match else_block.node {
1330 // If the else expression is another if-else expression, prevent it
1331 // from being formatted on a single line.
1332 // Note how we're passing the original shape, as the
1333 // cost of "else" should not cascade.
1334 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1335 ControlFlow::new_if(
1339 next_else_block.as_ref().map(|e| &**e),
1342 mk_sp(else_block.span.lo(), self.span.hi()),
1343 ).rewrite(context, shape)
1345 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1346 ControlFlow::new_if(
1350 next_else_block.as_ref().map(|e| &**e),
1353 mk_sp(else_block.span.lo(), self.span.hi()),
1354 ).rewrite(context, shape)
1357 last_in_chain = true;
1358 // When rewriting a block, the width is only used for single line
1359 // blocks, passing 1 lets us avoid that.
1360 let else_shape = Shape {
1361 width: min(1, shape.width),
1364 format_expr(else_block, ExprType::Statement, context, else_shape)
1368 let between_kwd_else_block = mk_sp(
1369 self.block.span.hi(),
1372 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1374 let between_kwd_else_block_comment =
1375 extract_comment(between_kwd_else_block, context, shape);
1377 let after_else = mk_sp(
1380 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1381 else_block.span.lo(),
1383 let after_else_comment = extract_comment(after_else, context, shape);
1385 let between_sep = match context.config.control_brace_style() {
1386 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1389 ControlBraceStyle::AlwaysSameLine => " ",
1391 let after_sep = match context.config.control_brace_style() {
1392 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1399 between_kwd_else_block_comment
1401 .map_or(between_sep, |s| &**s),
1402 after_else_comment.as_ref().map_or(after_sep, |s| &**s)
1405 result.push_str(&try_opt!(rewrite));
1412 fn rewrite_label(label: Option<ast::SpannedIdent>) -> Cow<'static, str> {
1414 Some(ident) => Cow::from(format!("{}: ", ident.node)),
1415 None => Cow::from(""),
1419 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1420 match rewrite_missing_comment(span, shape, context) {
1421 Some(ref comment) if !comment.is_empty() => Some(format!(
1422 "\n{indent}{}\n{indent}",
1424 indent = shape.indent.to_string(context.config)
1430 fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool {
1431 let snippet = codemap.span_to_snippet(block.span).unwrap();
1432 contains_comment(&snippet)
1435 // Checks that a block contains no statements, an expression and no comments.
1436 // FIXME: incorrectly returns false when comment is contained completely within
1438 pub fn is_simple_block(block: &ast::Block, codemap: &CodeMap) -> bool {
1439 (block.stmts.len() == 1 && stmt_is_expr(&block.stmts[0])
1440 && !block_contains_comment(block, codemap))
1443 /// Checks whether a block contains at most one statement or expression, and no comments.
1444 pub fn is_simple_block_stmt(block: &ast::Block, codemap: &CodeMap) -> bool {
1445 block.stmts.len() <= 1 && !block_contains_comment(block, codemap)
1448 /// Checks whether a block contains no statements, expressions, or comments.
1449 pub fn is_empty_block(block: &ast::Block, codemap: &CodeMap) -> bool {
1450 block.stmts.is_empty() && !block_contains_comment(block, codemap)
1453 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1455 ast::StmtKind::Expr(..) => true,
1460 fn is_unsafe_block(block: &ast::Block) -> bool {
1461 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1468 // A simple wrapper type against ast::Arm. Used inside write_list().
1469 struct ArmWrapper<'a> {
1470 pub arm: &'a ast::Arm,
1471 // True if the arm is the last one in match expression. Used to decide on whether we should add
1472 // trailing comma to the match arm when `config.trailing_comma() == Never`.
1476 impl<'a> ArmWrapper<'a> {
1477 pub fn new(arm: &'a ast::Arm, is_last: bool) -> ArmWrapper<'a> {
1478 ArmWrapper { arm, is_last }
1482 impl<'a> Rewrite for ArmWrapper<'a> {
1483 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1484 rewrite_match_arm(context, self.arm, shape, self.is_last)
1489 context: &RewriteContext,
1494 attrs: &[ast::Attribute],
1495 ) -> Option<String> {
1496 if arms.is_empty() {
1500 // Do not take the rhs overhead from the upper expressions into account
1501 // when rewriting match condition.
1502 let new_width = try_opt!(context.config.max_width().checked_sub(shape.used_width()));
1503 let cond_shape = Shape {
1508 let cond_shape = match context.config.control_style() {
1509 Style::Legacy => try_opt!(cond_shape.shrink_left(6)),
1510 Style::Rfc => try_opt!(cond_shape.offset_left(6)),
1512 let cond_str = try_opt!(cond.rewrite(context, cond_shape));
1513 let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config);
1514 let block_sep = match context.config.control_brace_style() {
1515 ControlBraceStyle::AlwaysNextLine => &alt_block_sep,
1516 _ if last_line_extendable(&cond_str) => " ",
1518 _ if cond_str.contains('\n') || cond_str.len() + 2 > cond_shape.width => &alt_block_sep,
1522 let nested_indent_str = shape
1524 .block_indent(context.config)
1525 .to_string(context.config);
1526 // Inner attributes.
1527 let inner_attrs = &inner_attributes(attrs);
1528 let inner_attrs_str = if inner_attrs.is_empty() {
1533 .rewrite(context, shape)
1534 .map(|s| format!("{}{}\n", nested_indent_str, s))
1538 let open_brace_pos = if inner_attrs.is_empty() {
1541 .span_after(mk_sp(cond.span.hi(), arms[0].span().lo()), "{")
1543 inner_attrs[inner_attrs.len() - 1].span().hi()
1546 let arm_indent_str = if context.config.indent_match_arms() {
1549 shape.indent.to_string(context.config)
1553 "match {}{}{{\n{}{}{}\n{}}}",
1558 try_opt!(rewrite_match_arms(
1565 shape.indent.to_string(context.config),
1569 fn arm_comma(config: &Config, body: &ast::Expr, is_last: bool) -> &'static str {
1570 if is_last && config.trailing_comma() == SeparatorTactic::Never {
1572 } else if config.match_block_trailing_comma() {
1574 } else if let ast::ExprKind::Block(ref block) = body.node {
1575 if let ast::BlockCheckMode::Default = block.rules {
1585 fn rewrite_match_arms(
1586 context: &RewriteContext,
1590 open_brace_pos: BytePos,
1591 ) -> Option<String> {
1592 let arm_shape = if context.config.indent_match_arms() {
1593 shape.block_indent(context.config.tab_spaces())
1595 shape.block_indent(0)
1596 }.with_max_width(context.config);
1598 let arm_len = arms.len();
1599 let is_last_iter = repeat(false)
1600 .take(arm_len.checked_sub(1).unwrap_or(0))
1601 .chain(repeat(true));
1602 let items = itemize_list(
1606 .map(|(arm, is_last)| ArmWrapper::new(arm, is_last)),
1608 |arm| arm.arm.span().lo(),
1609 |arm| arm.arm.span().hi(),
1610 |arm| arm.rewrite(context, arm_shape),
1615 let arms_vec: Vec<_> = items.collect();
1616 let fmt = ListFormatting {
1617 tactic: DefinitiveListTactic::Vertical,
1618 // We will add/remove commas inside `arm.rewrite()`, and hence no separator here.
1620 trailing_separator: SeparatorTactic::Never,
1621 separator_place: SeparatorPlace::Back,
1623 ends_with_newline: true,
1624 preserve_newline: true,
1625 config: context.config,
1628 write_list(&arms_vec, &fmt)
1631 fn rewrite_match_arm(
1632 context: &RewriteContext,
1636 ) -> Option<String> {
1637 let (missing_span, attrs_str) = if !arm.attrs.is_empty() {
1638 if contains_skip(&arm.attrs) {
1639 let (_, body) = flatten_arm_body(context, &arm.body);
1640 // `arm.span()` does not include trailing comma, add it manually.
1641 return Some(format!(
1643 context.snippet(arm.span()),
1644 arm_comma(context.config, body, is_last),
1649 arm.attrs[arm.attrs.len() - 1].span.hi(),
1650 arm.pats[0].span.lo(),
1652 try_opt!(arm.attrs.rewrite(context, shape)),
1655 (mk_sp(arm.span().lo(), arm.span().lo()), String::new())
1657 let pats_str = try_opt!(
1658 rewrite_match_pattern(context, &arm.pats, &arm.guard, shape).and_then(|pats_str| {
1659 combine_strs_with_missing_comments(
1674 arm.guard.is_some(),
1679 fn rewrite_match_pattern(
1680 context: &RewriteContext,
1681 pats: &[ptr::P<ast::Pat>],
1682 guard: &Option<ptr::P<ast::Expr>>,
1684 ) -> Option<String> {
1687 let pat_shape = try_opt!(shape.sub_width(5));
1689 let pat_strs = try_opt!(
1691 .map(|p| p.rewrite(context, pat_shape))
1692 .collect::<Option<Vec<_>>>()
1695 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1696 let tactic = definitive_tactic(
1698 ListTactic::HorizontalVertical,
1699 Separator::VerticalBar,
1702 let fmt = ListFormatting {
1705 trailing_separator: SeparatorTactic::Never,
1706 separator_place: context.config.match_pattern_separator_break_point(),
1708 ends_with_newline: false,
1709 preserve_newline: false,
1710 config: context.config,
1712 let pats_str = try_opt!(write_list(&items, &fmt));
1715 let guard_str = try_opt!(rewrite_guard(
1719 trimmed_last_line_width(&pats_str),
1722 Some(format!("{}{}", pats_str, guard_str))
1726 // @extend: true if the arm body can be put next to `=>`
1727 // @body: flattened body, if the body is block with a single expression
1728 fn flatten_arm_body<'a>(context: &'a RewriteContext, body: &'a ast::Expr) -> (bool, &'a ast::Expr) {
1730 ast::ExprKind::Block(ref block)
1731 if !is_unsafe_block(block) && is_simple_block(block, context.codemap) =>
1733 if let ast::StmtKind::Expr(ref expr) = block.stmts[0].node {
1735 !context.config.multiline_match_arm_forces_block()
1736 && expr.can_be_overflowed(context, 1),
1744 !context.config.multiline_match_arm_forces_block()
1745 && body.can_be_overflowed(context, 1),
1751 fn rewrite_match_body(
1752 context: &RewriteContext,
1753 body: &ptr::P<ast::Expr>,
1758 ) -> Option<String> {
1759 let (extend, body) = flatten_arm_body(context, body);
1761 let comma = arm_comma(context.config, body, is_last);
1762 let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config);
1763 let alt_block_sep = alt_block_sep.as_str();
1764 let (is_block, is_empty_block) = if let ast::ExprKind::Block(ref block) = body.node {
1765 (true, is_empty_block(block, context.codemap))
1770 let combine_orig_body = |body_str: &str| {
1771 let block_sep = match context.config.control_brace_style() {
1772 ControlBraceStyle::AlwaysNextLine if is_block => alt_block_sep,
1776 Some(format!("{} =>{}{}{}", pats_str, block_sep, body_str, comma))
1779 let forbid_same_line = has_guard && pats_str.contains('\n') && !is_empty_block;
1780 let next_line_indent = if is_block {
1783 shape.indent.block_indent(context.config)
1785 let combine_next_line_body = |body_str: &str| {
1787 return Some(format!(
1790 next_line_indent.to_string(context.config),
1795 let indent_str = shape.indent.to_string(context.config);
1796 let nested_indent_str = next_line_indent.to_string(context.config);
1797 let (body_prefix, body_suffix) = if context.config.wrap_match_arms() {
1798 let comma = if context.config.match_block_trailing_comma() {
1803 ("{", format!("\n{}}}{}", indent_str, comma))
1805 ("", String::from(","))
1808 let block_sep = match context.config.control_brace_style() {
1809 ControlBraceStyle::AlwaysNextLine => format!("{}{}\n", alt_block_sep, body_prefix),
1810 _ if body_prefix.is_empty() => "\n".to_owned(),
1811 _ if forbid_same_line => format!("{}{}\n", alt_block_sep, body_prefix),
1812 _ => format!(" {}\n", body_prefix),
1813 } + &nested_indent_str;
1824 // Let's try and get the arm body on the same line as the condition.
1826 let orig_body_shape = shape
1827 .offset_left(extra_offset(pats_str, shape) + 4)
1828 .and_then(|shape| shape.sub_width(comma.len()));
1829 let orig_body = if let Some(body_shape) = orig_body_shape {
1830 let rewrite = nop_block_collapse(
1831 format_expr(body, ExprType::Statement, context, body_shape),
1837 if !forbid_same_line
1839 || (!body_str.contains('\n') && body_str.len() <= body_shape.width)) =>
1841 return combine_orig_body(body_str);
1848 let orig_budget = orig_body_shape.map_or(0, |shape| shape.width);
1850 // Try putting body on the next line and see if it looks better.
1851 let next_line_body_shape = Shape::indented(next_line_indent, context.config);
1852 let next_line_body = nop_block_collapse(
1853 format_expr(body, ExprType::Statement, context, next_line_body_shape),
1854 next_line_body_shape.width,
1856 match (orig_body, next_line_body) {
1857 (Some(ref orig_str), Some(ref next_line_str))
1858 if forbid_same_line || prefer_next_line(orig_str, next_line_str) =>
1860 combine_next_line_body(next_line_str)
1862 (Some(ref orig_str), _) if extend && first_line_width(orig_str) <= orig_budget => {
1863 combine_orig_body(orig_str)
1865 (Some(ref orig_str), Some(ref next_line_str)) if orig_str.contains('\n') => {
1866 combine_next_line_body(next_line_str)
1868 (None, Some(ref next_line_str)) => combine_next_line_body(next_line_str),
1869 (None, None) => None,
1870 (Some(ref orig_str), _) => combine_orig_body(orig_str),
1874 // The `if ...` guard on a match arm.
1876 context: &RewriteContext,
1877 guard: &Option<ptr::P<ast::Expr>>,
1879 // The amount of space used up on this line for the pattern in
1880 // the arm (excludes offset).
1881 pattern_width: usize,
1882 ) -> Option<String> {
1883 if let Some(ref guard) = *guard {
1884 // First try to fit the guard string on the same line as the pattern.
1885 // 4 = ` if `, 5 = ` => {`
1886 let cond_shape = shape
1887 .offset_left(pattern_width + 4)
1888 .and_then(|s| s.sub_width(5));
1889 if let Some(cond_shape) = cond_shape {
1890 if let Some(cond_str) = guard.rewrite(context, cond_shape) {
1891 if !cond_str.contains('\n') || pattern_width <= context.config.tab_spaces() {
1892 return Some(format!(" if {}", cond_str));
1897 // Not enough space to put the guard after the pattern, try a newline.
1898 // 3 = `if `, 5 = ` => {`
1899 let cond_shape = Shape::indented(shape.indent.block_indent(context.config), context.config)
1901 .and_then(|s| s.sub_width(5));
1902 if let Some(cond_shape) = cond_shape {
1903 if let Some(cond_str) = guard.rewrite(context, cond_shape) {
1904 return Some(format!(
1906 cond_shape.indent.to_string(context.config),
1918 fn rewrite_pat_expr(
1919 context: &RewriteContext,
1920 pat: Option<&ast::Pat>,
1923 // Connecting piece between pattern and expression,
1924 // *without* trailing space.
1928 ) -> Option<String> {
1929 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, pat, expr);
1930 if let Some(pat) = pat {
1931 let matcher = if matcher.is_empty() {
1934 format!("{} ", matcher)
1937 try_opt!(try_opt!(shape.offset_left(matcher.len())).sub_width(connector.len()));
1938 let pat_string = try_opt!(pat.rewrite(context, pat_shape));
1939 let result = format!("{}{}{}", matcher, pat_string, connector);
1940 return rewrite_assign_rhs(context, result, expr, shape);
1943 let expr_rw = expr.rewrite(context, shape);
1944 // The expression may (partially) fit on the current line.
1945 // We do not allow splitting between `if` and condition.
1946 if keyword == "if" || expr_rw.is_some() {
1950 // The expression won't fit on the current line, jump to next.
1951 let nested_shape = shape
1952 .block_indent(context.config.tab_spaces())
1953 .with_max_width(context.config);
1954 let nested_indent_str = nested_shape.indent.to_string(context.config);
1955 expr.rewrite(context, nested_shape)
1956 .map(|expr_rw| format!("\n{}{}", nested_indent_str, expr_rw))
1959 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1960 let string_lit = context.snippet(span);
1962 if !context.config.format_strings() && !context.config.force_format_strings() {
1967 .all(|line| line.ends_with('\\'))
1969 let new_indent = shape.visual_indent(1).indent;
1970 return Some(String::from(
1976 new_indent.to_string(context.config),
1980 .collect::<Vec<_>>()
1985 return Some(string_lit);
1989 if !context.config.force_format_strings()
1990 && !string_requires_rewrite(context, span, &string_lit, shape)
1992 return Some(string_lit);
1995 let fmt = StringFormat {
2002 config: context.config,
2005 // Remove the quote characters.
2006 let str_lit = &string_lit[1..string_lit.len() - 1];
2008 rewrite_string(str_lit, &fmt)
2011 fn string_requires_rewrite(
2012 context: &RewriteContext,
2017 if context.codemap.lookup_char_pos(span.lo()).col.0 != shape.indent.width() {
2021 for (i, line) in string.lines().enumerate() {
2023 if line.len() > shape.width {
2026 } else if line.len() > shape.width + shape.indent.width() {
2034 pub fn rewrite_call(
2035 context: &RewriteContext,
2037 args: &[ptr::P<ast::Expr>],
2040 ) -> Option<String> {
2041 let force_trailing_comma = if context.inside_macro {
2042 span_ends_with_comma(context, span)
2049 &ptr_vec_to_ref_vec(&args),
2052 context.config.fn_call_width(),
2053 force_trailing_comma,
2057 pub fn rewrite_call_inner<'a, T>(
2058 context: &RewriteContext,
2063 args_max_width: usize,
2064 force_trailing_comma: bool,
2065 ) -> Result<String, Ordering>
2067 T: Rewrite + Spanned + ToExpr + 'a,
2069 // 2 = `( `, 1 = `(`
2070 let paren_overhead = if context.config.spaces_within_parens() {
2075 let used_width = extra_offset(callee_str, shape);
2076 let one_line_width = shape
2078 .checked_sub(used_width + 2 * paren_overhead)
2079 .ok_or(Ordering::Greater)?;
2081 let nested_shape = shape_from_fn_call_style(
2084 used_width + 2 * paren_overhead,
2085 used_width + paren_overhead,
2086 ).ok_or(Ordering::Greater)?;
2088 let span_lo = context.codemap.span_after(span, "(");
2089 let args_span = mk_sp(span_lo, span.hi());
2091 let (extendable, list_str) = rewrite_call_args(
2098 force_trailing_comma,
2099 ).ok_or(Ordering::Less)?;
2101 if !context.use_block_indent() && need_block_indent(&list_str, nested_shape) && !extendable {
2102 let mut new_context = context.clone();
2103 new_context.use_block = true;
2104 return rewrite_call_inner(
2111 force_trailing_comma,
2115 let args_shape = shape
2116 .sub_width(last_line_width(callee_str))
2117 .ok_or(Ordering::Less)?;
2121 wrap_args_with_parens(context, &list_str, extendable, args_shape, nested_shape)
2125 fn need_block_indent(s: &str, shape: Shape) -> bool {
2126 s.lines().skip(1).any(|s| {
2127 s.find(|c| !char::is_whitespace(c))
2128 .map_or(false, |w| w + 1 < shape.indent.width())
2132 fn rewrite_call_args<'a, T>(
2133 context: &RewriteContext,
2137 one_line_width: usize,
2138 args_max_width: usize,
2139 force_trailing_comma: bool,
2140 ) -> Option<(bool, String)>
2142 T: Rewrite + Spanned + ToExpr + 'a,
2144 let items = itemize_list(
2148 |item| item.span().lo(),
2149 |item| item.span().hi(),
2150 |item| item.rewrite(context, shape),
2155 let mut item_vec: Vec<_> = items.collect();
2157 // Try letting the last argument overflow to the next line with block
2158 // indentation. If its first line fits on one line with the other arguments,
2159 // we format the function arguments horizontally.
2160 let tactic = try_overflow_last_arg(
2169 let fmt = ListFormatting {
2172 trailing_separator: if force_trailing_comma {
2173 SeparatorTactic::Always
2174 } else if context.inside_macro || !context.use_block_indent() {
2175 SeparatorTactic::Never
2177 context.config.trailing_comma()
2179 separator_place: SeparatorPlace::Back,
2181 ends_with_newline: context.use_block_indent() && tactic == DefinitiveListTactic::Vertical,
2182 preserve_newline: false,
2183 config: context.config,
2186 write_list(&item_vec, &fmt).map(|args_str| {
2187 (tactic != DefinitiveListTactic::Vertical, args_str)
2191 fn try_overflow_last_arg<'a, T>(
2192 context: &RewriteContext,
2193 item_vec: &mut Vec<ListItem>,
2196 one_line_width: usize,
2197 args_max_width: usize,
2198 ) -> DefinitiveListTactic
2200 T: Rewrite + Spanned + ToExpr + 'a,
2202 let overflow_last = can_be_overflowed(context, args);
2204 // Replace the last item with its first line to see if it fits with
2206 let placeholder = if overflow_last {
2207 let mut context = context.clone();
2208 if let Some(expr) = args[args.len() - 1].to_expr() {
2209 if let ast::ExprKind::MethodCall(..) = expr.node {
2210 context.force_one_line_chain = true;
2213 last_arg_shape(&context, item_vec, shape, args_max_width).and_then(|arg_shape| {
2214 rewrite_last_arg_with_overflow(&context, args, &mut item_vec[args.len() - 1], arg_shape)
2220 let mut tactic = definitive_tactic(
2222 ListTactic::LimitedHorizontalVertical(args_max_width),
2227 // Replace the stub with the full overflowing last argument if the rewrite
2228 // succeeded and its first line fits with the other arguments.
2229 match (overflow_last, tactic, placeholder) {
2230 (true, DefinitiveListTactic::Horizontal, placeholder @ Some(..)) => {
2231 item_vec[args.len() - 1].item = placeholder;
2233 _ if args.len() >= 1 => {
2234 item_vec[args.len() - 1].item = args.last()
2235 .and_then(|last_arg| last_arg.rewrite(context, shape));
2236 tactic = definitive_tactic(
2238 ListTactic::LimitedHorizontalVertical(args_max_width),
2250 context: &RewriteContext,
2253 args_max_width: usize,
2254 ) -> Option<Shape> {
2255 let overhead = items.iter().rev().skip(1).fold(0, |acc, i| {
2256 acc + i.item.as_ref().map_or(0, |s| first_line_width(s))
2258 let max_width = min(args_max_width, shape.width);
2259 let arg_indent = if context.use_block_indent() {
2260 shape.block().indent.block_unindent(context.config)
2262 shape.block().indent
2265 width: try_opt!(max_width.checked_sub(overhead)),
2271 // Rewriting closure which is placed at the end of the function call's arg.
2272 // Returns `None` if the reformatted closure 'looks bad'.
2273 fn rewrite_last_closure(
2274 context: &RewriteContext,
2277 ) -> Option<String> {
2278 if let ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) = expr.node {
2279 let body = match body.node {
2280 ast::ExprKind::Block(ref block) if block.stmts.len() == 1 => {
2281 stmt_expr(&block.stmts[0]).unwrap_or(body)
2285 let (prefix, extra_offset) = try_opt!(rewrite_closure_fn_decl(
2293 // If the closure goes multi line before its body, do not overflow the closure.
2294 if prefix.contains('\n') {
2297 let body_shape = try_opt!(shape.offset_left(extra_offset));
2298 // When overflowing the closure which consists of a single control flow expression,
2299 // force to use block if its condition uses multi line.
2300 let is_multi_lined_cond = rewrite_cond(context, body, body_shape)
2301 .map(|cond| cond.contains('\n') || cond.len() > body_shape.width)
2303 if is_multi_lined_cond {
2304 return rewrite_closure_with_block(context, body_shape, &prefix, body);
2307 // Seems fine, just format the closure in usual manner.
2308 return expr.rewrite(context, shape);
2313 fn rewrite_last_arg_with_overflow<'a, T>(
2314 context: &RewriteContext,
2316 last_item: &mut ListItem,
2320 T: Rewrite + Spanned + ToExpr + 'a,
2322 let last_arg = args[args.len() - 1];
2323 let rewrite = if let Some(expr) = last_arg.to_expr() {
2325 // When overflowing the closure which consists of a single control flow expression,
2326 // force to use block if its condition uses multi line.
2327 ast::ExprKind::Closure(..) => {
2328 // If the argument consists of multiple closures, we do not overflow
2329 // the last closure.
2334 .filter_map(|arg| arg.to_expr())
2335 .any(|expr| match expr.node {
2336 ast::ExprKind::Closure(..) => true,
2341 rewrite_last_closure(context, expr, shape)
2344 _ => expr.rewrite(context, shape),
2347 last_arg.rewrite(context, shape)
2350 if let Some(rewrite) = rewrite {
2351 let rewrite_first_line = Some(rewrite[..first_line_width(&rewrite)].to_owned());
2352 last_item.item = rewrite_first_line;
2359 fn can_be_overflowed<'a, T>(context: &RewriteContext, args: &[&T]) -> bool
2361 T: Rewrite + Spanned + ToExpr + 'a,
2364 .map_or(false, |x| x.can_be_overflowed(context, args.len()))
2367 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
2369 ast::ExprKind::Match(..) => {
2370 (context.use_block_indent() && args_len == 1)
2371 || (context.config.fn_call_style() == IndentStyle::Visual && args_len > 1)
2373 ast::ExprKind::If(..) |
2374 ast::ExprKind::IfLet(..) |
2375 ast::ExprKind::ForLoop(..) |
2376 ast::ExprKind::Loop(..) |
2377 ast::ExprKind::While(..) |
2378 ast::ExprKind::WhileLet(..) => {
2379 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
2381 ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => {
2382 context.use_block_indent()
2383 || context.config.fn_call_style() == IndentStyle::Visual && args_len > 1
2385 ast::ExprKind::Array(..) |
2386 ast::ExprKind::Call(..) |
2387 ast::ExprKind::Mac(..) |
2388 ast::ExprKind::MethodCall(..) |
2389 ast::ExprKind::Struct(..) |
2390 ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
2391 ast::ExprKind::AddrOf(_, ref expr) |
2392 ast::ExprKind::Box(ref expr) |
2393 ast::ExprKind::Try(ref expr) |
2394 ast::ExprKind::Unary(_, ref expr) |
2395 ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
2400 pub fn wrap_args_with_parens(
2401 context: &RewriteContext,
2403 is_extendable: bool,
2405 nested_shape: Shape,
2407 if !context.use_block_indent()
2408 || (context.inside_macro && !args_str.contains('\n')
2409 && args_str.len() + paren_overhead(context) <= shape.width) || is_extendable
2411 if context.config.spaces_within_parens() && !args_str.is_empty() {
2412 format!("( {} )", args_str)
2414 format!("({})", args_str)
2419 nested_shape.indent.to_string(context.config),
2421 shape.block().indent.to_string(context.config)
2426 fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
2427 let snippet = context.snippet(span);
2429 .trim_right_matches(|c: char| c == ')' || c.is_whitespace())
2433 fn rewrite_paren(context: &RewriteContext, subexpr: &ast::Expr, shape: Shape) -> Option<String> {
2434 debug!("rewrite_paren, shape: {:?}", shape);
2435 let total_paren_overhead = paren_overhead(context);
2436 let paren_overhead = total_paren_overhead / 2;
2437 let sub_shape = try_opt!(
2439 .offset_left(paren_overhead)
2440 .and_then(|s| s.sub_width(paren_overhead))
2443 let paren_wrapper = |s: &str| if context.config.spaces_within_parens() && !s.is_empty() {
2444 format!("( {} )", s)
2449 let subexpr_str = try_opt!(subexpr.rewrite(context, sub_shape));
2450 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
2452 if subexpr_str.contains('\n')
2453 || first_line_width(&subexpr_str) + total_paren_overhead <= shape.width
2455 Some(paren_wrapper(&subexpr_str))
2464 context: &RewriteContext,
2466 ) -> Option<String> {
2467 let expr_str = try_opt!(expr.rewrite(context, shape));
2469 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
2475 let offset = last_line_width(&expr_str) + lbr.len();
2476 let rhs_overhead = shape.rhs_overhead(context.config);
2477 let index_shape = if expr_str.contains('\n') {
2478 Shape::legacy(context.config.max_width(), shape.indent)
2479 .offset_left(offset)
2480 .and_then(|shape| shape.sub_width(rbr.len() + rhs_overhead))
2482 shape.visual_indent(offset).sub_width(offset + rbr.len())
2484 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
2486 // Return if index fits in a single line.
2487 match orig_index_rw {
2488 Some(ref index_str) if !index_str.contains('\n') => {
2489 return Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr));
2494 // Try putting index on the next line and see if it fits in a single line.
2495 let indent = shape.indent.block_indent(context.config);
2496 let index_shape = try_opt!(Shape::indented(indent, context.config).offset_left(lbr.len()));
2497 let index_shape = try_opt!(index_shape.sub_width(rbr.len() + rhs_overhead));
2498 let new_index_rw = index.rewrite(context, index_shape);
2499 match (orig_index_rw, new_index_rw) {
2500 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
2503 indent.to_string(context.config),
2508 (None, Some(ref new_index_str)) => Some(format!(
2511 indent.to_string(context.config),
2516 (Some(ref index_str), _) => Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr)),
2521 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: &Option<&ast::Expr>) -> bool {
2526 fields.iter().all(|field| !field.is_shorthand)
2529 fn rewrite_struct_lit<'a>(
2530 context: &RewriteContext,
2532 fields: &'a [ast::Field],
2533 base: Option<&'a ast::Expr>,
2536 ) -> Option<String> {
2537 debug!("rewrite_struct_lit: shape {:?}", shape);
2539 enum StructLitField<'a> {
2540 Regular(&'a ast::Field),
2541 Base(&'a ast::Expr),
2545 let path_shape = try_opt!(shape.sub_width(2));
2546 let path_str = try_opt!(rewrite_path(
2554 if fields.is_empty() && base.is_none() {
2555 return Some(format!("{} {{}}", path_str));
2558 // Foo { a: Foo } - indent is +3, width is -5.
2559 let (h_shape, v_shape) = try_opt!(struct_lit_shape(shape, context, path_str.len() + 3, 2));
2561 let one_line_width = h_shape.map_or(0, |shape| shape.width);
2562 let body_lo = context.codemap.span_after(span, "{");
2563 let fields_str = if struct_lit_can_be_aligned(fields, &base)
2564 && context.config.struct_field_align_threshold() > 0
2566 try_opt!(rewrite_with_alignment(
2570 mk_sp(body_lo, span.hi()),
2574 let field_iter = fields
2576 .map(StructLitField::Regular)
2577 .chain(base.into_iter().map(StructLitField::Base));
2579 let span_lo = |item: &StructLitField| match *item {
2580 StructLitField::Regular(field) => field.span().lo(),
2581 StructLitField::Base(expr) => {
2582 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
2583 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
2584 let pos = snippet.find_uncommented("..").unwrap();
2585 last_field_hi + BytePos(pos as u32)
2588 let span_hi = |item: &StructLitField| match *item {
2589 StructLitField::Regular(field) => field.span().hi(),
2590 StructLitField::Base(expr) => expr.span.hi(),
2592 let rewrite = |item: &StructLitField| match *item {
2593 StructLitField::Regular(field) => {
2594 // The 1 taken from the v_budget is for the comma.
2595 rewrite_field(context, field, try_opt!(v_shape.sub_width(1)), 0)
2597 StructLitField::Base(expr) => {
2599 expr.rewrite(context, try_opt!(v_shape.offset_left(2)))
2600 .map(|s| format!("..{}", s))
2604 let items = itemize_list(
2615 let item_vec = items.collect::<Vec<_>>();
2617 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
2618 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
2619 let fmt = struct_lit_formatting(nested_shape, tactic, context, base.is_some());
2621 try_opt!(write_list(&item_vec, &fmt))
2624 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
2625 Some(format!("{} {{{}}}", path_str, fields_str))
2627 // FIXME if context.config.struct_lit_style() == Visual, but we run out
2628 // of space, we should fall back to BlockIndent.
2631 pub fn wrap_struct_field(
2632 context: &RewriteContext,
2635 nested_shape: Shape,
2636 one_line_width: usize,
2638 if context.config.struct_lit_style() == IndentStyle::Block
2639 && (fields_str.contains('\n')
2640 || context.config.struct_lit_multiline_style() == MultilineStyle::ForceMulti
2641 || fields_str.len() > one_line_width)
2645 nested_shape.indent.to_string(context.config),
2647 shape.indent.to_string(context.config)
2650 // One liner or visual indent.
2651 format!(" {} ", fields_str)
2655 pub fn struct_lit_field_separator(config: &Config) -> &str {
2657 config.space_before_struct_lit_field_colon(),
2658 config.space_after_struct_lit_field_colon(),
2662 pub fn rewrite_field(
2663 context: &RewriteContext,
2666 prefix_max_width: usize,
2667 ) -> Option<String> {
2668 if contains_skip(&field.attrs) {
2670 context.snippet(field.span()),
2671 context.config.max_width(),
2675 let name = &field.ident.node.to_string();
2676 if field.is_shorthand {
2677 Some(name.to_string())
2679 let mut separator = String::from(struct_lit_field_separator(context.config));
2680 for _ in 0..prefix_max_width.checked_sub(name.len()).unwrap_or(0) {
2681 separator.push(' ');
2683 let overhead = name.len() + separator.len();
2684 let expr_shape = try_opt!(shape.offset_left(overhead));
2685 let expr = field.expr.rewrite(context, expr_shape);
2687 let mut attrs_str = try_opt!(field.attrs.rewrite(context, shape));
2688 if !attrs_str.is_empty() {
2689 attrs_str.push_str(&format!("\n{}", shape.indent.to_string(context.config)));
2693 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
2695 let expr_offset = shape.indent.block_indent(context.config);
2698 .rewrite(context, Shape::indented(expr_offset, context.config));
2704 expr_offset.to_string(context.config),
2713 fn shape_from_fn_call_style(
2714 context: &RewriteContext,
2718 ) -> Option<Shape> {
2719 if context.use_block_indent() {
2723 .block_indent(context.config.tab_spaces())
2724 .with_max_width(context.config)
2727 shape.visual_indent(offset).sub_width(overhead)
2731 fn rewrite_tuple_in_visual_indent_style<'a, T>(
2732 context: &RewriteContext,
2738 T: Rewrite + Spanned + ToExpr + 'a,
2740 let mut items = items.iter();
2741 // In case of length 1, need a trailing comma
2742 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
2743 if items.len() == 1 {
2745 let nested_shape = try_opt!(shape.sub_width(3)).visual_indent(1);
2746 return items.next().unwrap().rewrite(context, nested_shape).map(
2747 |s| if context.config.spaces_within_parens() {
2748 format!("( {}, )", s)
2755 let list_lo = context.codemap.span_after(span, "(");
2756 let nested_shape = try_opt!(shape.sub_width(2)).visual_indent(1);
2757 let items = itemize_list(
2761 |item| item.span().lo(),
2762 |item| item.span().hi(),
2763 |item| item.rewrite(context, nested_shape),
2765 span.hi() - BytePos(1),
2768 let item_vec: Vec<_> = items.collect();
2769 let tactic = definitive_tactic(
2771 ListTactic::HorizontalVertical,
2775 let fmt = ListFormatting {
2778 trailing_separator: SeparatorTactic::Never,
2779 separator_place: SeparatorPlace::Back,
2781 ends_with_newline: false,
2782 preserve_newline: false,
2783 config: context.config,
2785 let list_str = try_opt!(write_list(&item_vec, &fmt));
2787 if context.config.spaces_within_parens() && !list_str.is_empty() {
2788 Some(format!("( {} )", list_str))
2790 Some(format!("({})", list_str))
2794 pub fn rewrite_tuple<'a, T>(
2795 context: &RewriteContext,
2801 T: Rewrite + Spanned + ToExpr + 'a,
2803 debug!("rewrite_tuple {:?}", shape);
2804 if context.use_block_indent() {
2805 // We use the same rule as function calls for rewriting tuples.
2806 let force_trailing_comma = if context.inside_macro {
2807 span_ends_with_comma(context, span)
2817 context.config.fn_call_width(),
2818 force_trailing_comma,
2821 rewrite_tuple_in_visual_indent_style(context, items, span, shape)
2825 pub fn rewrite_unary_prefix<R: Rewrite>(
2826 context: &RewriteContext,
2830 ) -> Option<String> {
2832 .rewrite(context, try_opt!(shape.offset_left(prefix.len())))
2833 .map(|r| format!("{}{}", prefix, r))
2836 // FIXME: this is probably not correct for multi-line Rewrites. we should
2837 // subtract suffix.len() from the last line budget, not the first!
2838 pub fn rewrite_unary_suffix<R: Rewrite>(
2839 context: &RewriteContext,
2843 ) -> Option<String> {
2845 .rewrite(context, try_opt!(shape.sub_width(suffix.len())))
2852 fn rewrite_unary_op(
2853 context: &RewriteContext,
2857 ) -> Option<String> {
2858 // For some reason, an UnOp is not spanned like BinOp!
2859 let operator_str = match *op {
2860 ast::UnOp::Deref => "*",
2861 ast::UnOp::Not => "!",
2862 ast::UnOp::Neg => "-",
2864 rewrite_unary_prefix(context, operator_str, expr, shape)
2867 fn rewrite_assignment(
2868 context: &RewriteContext,
2871 op: Option<&ast::BinOp>,
2873 ) -> Option<String> {
2874 let operator_str = match op {
2875 Some(op) => context.snippet(op.span),
2876 None => "=".to_owned(),
2879 // 1 = space between lhs and operator.
2880 let lhs_shape = try_opt!(shape.sub_width(operator_str.len() + 1));
2881 let lhs_str = format!(
2883 try_opt!(lhs.rewrite(context, lhs_shape)),
2887 rewrite_assign_rhs(context, lhs_str, rhs, shape)
2890 // The left hand side must contain everything up to, and including, the
2891 // assignment operator.
2892 pub fn rewrite_assign_rhs<S: Into<String>>(
2893 context: &RewriteContext,
2897 ) -> Option<String> {
2898 let lhs = lhs.into();
2899 let last_line_width = last_line_width(&lhs) - if lhs.contains('\n') {
2900 shape.indent.width()
2904 // 1 = space between operator and rhs.
2905 let orig_shape = try_opt!(shape.offset_left(last_line_width + 1));
2906 let rhs = try_opt!(choose_rhs(
2910 ex.rewrite(context, orig_shape)
2916 context: &RewriteContext,
2919 orig_rhs: Option<String>,
2920 ) -> Option<String> {
2922 Some(ref new_str) if !new_str.contains('\n') => Some(format!(" {}", new_str)),
2924 // Expression did not fit on the same line as the identifier.
2925 // Try splitting the line and see if that works better.
2926 let new_shape = try_opt!(
2928 shape.block().indent.block_indent(context.config),
2930 ).sub_width(shape.rhs_overhead(context.config))
2932 let new_rhs = expr.rewrite(context, new_shape);
2933 let new_indent_str = &new_shape.indent.to_string(context.config);
2935 match (orig_rhs, new_rhs) {
2936 (Some(ref orig_rhs), Some(ref new_rhs)) if prefer_next_line(orig_rhs, new_rhs) => {
2937 Some(format!("\n{}{}", new_indent_str, new_rhs))
2939 (None, Some(ref new_rhs)) => Some(format!("\n{}{}", new_indent_str, new_rhs)),
2940 (None, None) => None,
2941 (Some(ref orig_rhs), _) => Some(format!(" {}", orig_rhs)),
2947 fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str) -> bool {
2948 fn count_line_breaks(src: &str) -> usize {
2949 src.chars().filter(|&x| x == '\n').count()
2952 !next_line_rhs.contains('\n')
2953 || count_line_breaks(orig_rhs) > count_line_breaks(next_line_rhs) + 1
2956 fn rewrite_expr_addrof(
2957 context: &RewriteContext,
2958 mutability: ast::Mutability,
2961 ) -> Option<String> {
2962 let operator_str = match mutability {
2963 ast::Mutability::Immutable => "&",
2964 ast::Mutability::Mutable => "&mut ",
2966 rewrite_unary_prefix(context, operator_str, expr, shape)
2970 fn to_expr(&self) -> Option<&ast::Expr>;
2971 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool;
2974 impl ToExpr for ast::Expr {
2975 fn to_expr(&self) -> Option<&ast::Expr> {
2979 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2980 can_be_overflowed_expr(context, self, len)
2984 impl ToExpr for ast::Ty {
2985 fn to_expr(&self) -> Option<&ast::Expr> {
2989 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2990 can_be_overflowed_type(context, self, len)
2994 impl<'a> ToExpr for TuplePatField<'a> {
2995 fn to_expr(&self) -> Option<&ast::Expr> {
2999 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
3000 can_be_overflowed_pat(context, self, len)
3004 impl<'a> ToExpr for ast::StructField {
3005 fn to_expr(&self) -> Option<&ast::Expr> {
3009 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
3014 impl<'a> ToExpr for MacroArg {
3015 fn to_expr(&self) -> Option<&ast::Expr> {
3017 MacroArg::Expr(ref expr) => Some(expr),
3022 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
3024 MacroArg::Expr(ref expr) => can_be_overflowed_expr(context, expr, len),
3025 MacroArg::Ty(ref ty) => can_be_overflowed_type(context, ty, len),
3026 MacroArg::Pat(..) => false,