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;
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 shape::{Indent, Shape};
34 use string::{rewrite_string, StringFormat};
35 use types::{can_be_overflowed_type, rewrite_path, PathContext};
36 use utils::{colon_spaces, contains_skip, extra_offset, first_line_width, inner_attributes,
37 last_line_extendable, last_line_width, left_most_sub_expr, mk_sp, outer_attributes,
38 paren_overhead, ptr_vec_to_ref_vec, semicolon_for_stmt, stmt_expr,
39 trimmed_last_line_width};
40 use vertical::rewrite_with_alignment;
41 use visitor::FmtVisitor;
43 impl Rewrite for ast::Expr {
44 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
45 format_expr(self, ExprType::SubExpression, context, shape)
49 #[derive(Copy, Clone, PartialEq)]
58 context: &RewriteContext,
61 skip_out_of_file_lines_range!(context, expr.span);
63 if contains_skip(&*expr.attrs) {
64 return Some(context.snippet(expr.span()));
67 let expr_rw = match expr.node {
68 ast::ExprKind::Array(ref expr_vec) => rewrite_array(
69 expr_vec.iter().map(|e| &**e),
70 mk_sp(context.codemap.span_after(expr.span, "["), expr.span.hi()),
75 ast::ExprKind::Lit(ref l) => rewrite_literal(context, l, shape),
76 ast::ExprKind::Call(ref callee, ref args) => {
77 let inner_span = mk_sp(callee.span.hi(), expr.span.hi());
78 let callee_str = try_opt!(callee.rewrite(context, shape));
79 rewrite_call(context, &callee_str, &args, inner_span, shape)
81 ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape),
82 ast::ExprKind::Binary(ref op, ref lhs, ref rhs) => {
83 // FIXME: format comments between operands and operator
88 &format!(" {} ", context.snippet(op.span)),
92 context.config.binop_separator(),
95 ast::ExprKind::Unary(ref op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape),
96 ast::ExprKind::Struct(ref path, ref fields, ref base) => rewrite_struct_lit(
100 base.as_ref().map(|e| &**e),
104 ast::ExprKind::Tup(ref items) => {
105 rewrite_tuple(context, &ptr_vec_to_ref_vec(&items), expr.span, shape)
107 ast::ExprKind::If(..) |
108 ast::ExprKind::IfLet(..) |
109 ast::ExprKind::ForLoop(..) |
110 ast::ExprKind::Loop(..) |
111 ast::ExprKind::While(..) |
112 ast::ExprKind::WhileLet(..) => to_control_flow(expr, expr_type)
113 .and_then(|control_flow| control_flow.rewrite(context, shape)),
114 ast::ExprKind::Block(ref block) => {
116 ExprType::Statement => {
117 if is_unsafe_block(block) {
118 block.rewrite(context, shape)
119 } else if let rw @ Some(_) = rewrite_empty_block(context, block, shape) {
120 // Rewrite block without trying to put it in a single line.
123 let prefix = try_opt!(block_prefix(context, block, shape));
124 rewrite_block_with_visitor(context, &prefix, block, shape)
127 ExprType::SubExpression => block.rewrite(context, shape),
130 ast::ExprKind::Match(ref cond, ref arms) => {
131 rewrite_match(context, cond, arms, shape, expr.span, &expr.attrs)
133 ast::ExprKind::Path(ref qself, ref path) => {
134 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
136 ast::ExprKind::Assign(ref lhs, ref rhs) => {
137 rewrite_assignment(context, lhs, rhs, None, shape)
139 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
140 rewrite_assignment(context, lhs, rhs, Some(op), shape)
142 ast::ExprKind::Continue(ref opt_ident) => {
143 let id_str = match *opt_ident {
144 Some(ident) => format!(" {}", ident.node),
145 None => String::new(),
147 Some(format!("continue{}", id_str))
149 ast::ExprKind::Break(ref opt_ident, ref opt_expr) => {
150 let id_str = match *opt_ident {
151 Some(ident) => format!(" {}", ident.node),
152 None => String::new(),
155 if let Some(ref expr) = *opt_expr {
156 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
158 Some(format!("break{}", id_str))
161 ast::ExprKind::Yield(ref opt_expr) => if let Some(ref expr) = *opt_expr {
162 rewrite_unary_prefix(context, "yield ", &**expr, shape)
164 Some("yield".to_string())
166 ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) => {
167 rewrite_closure(capture, fn_decl, body, expr.span, context, shape)
169 ast::ExprKind::Try(..) |
170 ast::ExprKind::Field(..) |
171 ast::ExprKind::TupField(..) |
172 ast::ExprKind::MethodCall(..) => rewrite_chain(expr, context, shape),
173 ast::ExprKind::Mac(ref mac) => {
174 // Failure to rewrite a marco should not imply failure to
175 // rewrite the expression.
176 rewrite_macro(mac, None, context, shape, MacroPosition::Expression)
177 .or_else(|| Some(context.snippet(expr.span)))
179 ast::ExprKind::Ret(None) => Some("return".to_owned()),
180 ast::ExprKind::Ret(Some(ref expr)) => {
181 rewrite_unary_prefix(context, "return ", &**expr, shape)
183 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
184 ast::ExprKind::AddrOf(mutability, ref expr) => {
185 rewrite_expr_addrof(context, mutability, expr, shape)
187 ast::ExprKind::Cast(ref expr, ref ty) => rewrite_pair(
195 SeparatorPlace::Front,
197 ast::ExprKind::Type(ref expr, ref ty) => rewrite_pair(
205 SeparatorPlace::Back,
207 ast::ExprKind::Index(ref expr, ref index) => {
208 rewrite_index(&**expr, &**index, context, shape)
210 ast::ExprKind::Repeat(ref expr, ref repeats) => {
211 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
224 SeparatorPlace::Back,
227 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
228 let delim = match limits {
229 ast::RangeLimits::HalfOpen => "..",
230 ast::RangeLimits::Closed => "..=",
233 fn needs_space_before_range(context: &RewriteContext, lhs: &ast::Expr) -> bool {
235 ast::ExprKind::Lit(ref lit) => match lit.node {
236 ast::LitKind::FloatUnsuffixed(..) => {
237 context.snippet(lit.span).ends_with('.')
245 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
246 (Some(lhs), Some(rhs)) => {
247 let sp_delim = if context.config.spaces_around_ranges() {
248 format!(" {} ", delim)
249 } else if needs_space_before_range(context, lhs) {
250 format!(" {}", delim)
262 SeparatorPlace::Front,
265 (None, Some(rhs)) => {
266 let sp_delim = if context.config.spaces_around_ranges() {
267 format!("{} ", delim)
271 rewrite_unary_prefix(context, &sp_delim, &*rhs, shape)
273 (Some(lhs), None) => {
274 let sp_delim = if context.config.spaces_around_ranges() {
275 format!(" {}", delim)
279 rewrite_unary_suffix(context, &sp_delim, &*lhs, shape)
281 (None, None) => Some(delim.into()),
284 // We do not format these expressions yet, but they should still
285 // satisfy our width restrictions.
286 ast::ExprKind::InPlace(..) | ast::ExprKind::InlineAsm(..) => {
287 Some(context.snippet(expr.span))
289 ast::ExprKind::Catch(ref block) => {
290 if let rw @ Some(_) = rewrite_single_line_block(context, "do catch ", block, shape) {
294 let budget = shape.width.checked_sub(9).unwrap_or(0);
298 try_opt!(block.rewrite(context, Shape::legacy(budget, shape.indent)))
305 .and_then(|expr_str| {
306 recover_comment_removed(expr_str, expr.span, context)
308 .and_then(|expr_str| {
309 let attrs = outer_attributes(&expr.attrs);
310 let attrs_str = try_opt!(attrs.rewrite(context, shape));
312 attrs.last().map_or(expr.span.lo(), |attr| attr.span.hi()),
315 combine_strs_with_missing_comments(context, &attrs_str, &expr_str, span, shape, false)
319 pub fn rewrite_pair<LHS, RHS>(
325 context: &RewriteContext,
327 separator_place: SeparatorPlace,
333 let lhs_overhead = match separator_place {
334 SeparatorPlace::Back => shape.used_width() + prefix.len() + infix.trim_right().len(),
335 SeparatorPlace::Front => shape.used_width(),
337 let lhs_shape = Shape {
338 width: context.budget(lhs_overhead),
341 let lhs_result = try_opt!(
342 lhs.rewrite(context, lhs_shape)
343 .map(|lhs_str| format!("{}{}", prefix, lhs_str))
346 // Try to the both lhs and rhs on the same line.
347 let rhs_orig_result = shape
348 .offset_left(last_line_width(&lhs_result) + infix.len())
349 .and_then(|s| s.sub_width(suffix.len()))
350 .and_then(|rhs_shape| rhs.rewrite(context, rhs_shape));
351 if let Some(ref rhs_result) = rhs_orig_result {
352 // If the rhs looks like block expression, we allow it to stay on the same line
353 // with the lhs even if it is multi-lined.
354 let allow_same_line = rhs_result
357 .map(|first_line| first_line.ends_with('{'))
359 if !rhs_result.contains('\n') || allow_same_line {
360 let one_line_width = last_line_width(&lhs_result) + infix.len()
361 + first_line_width(&rhs_result) + suffix.len();
362 if one_line_width <= shape.width {
363 return Some(format!("{}{}{}{}", lhs_result, infix, rhs_result, suffix));
368 // We have to use multiple lines.
369 // Re-evaluate the rhs because we have more space now:
370 let mut rhs_shape = try_opt!(match context.config.control_style() {
371 Style::Legacy => shape
372 .sub_width(suffix.len() + prefix.len())
373 .map(|s| s.visual_indent(prefix.len())),
375 // Try to calculate the initial constraint on the right hand side.
376 let rhs_overhead = shape.rhs_overhead(context.config);
377 Shape::indented(shape.indent.block_indent(context.config), context.config)
378 .sub_width(rhs_overhead)
381 let infix = match separator_place {
382 SeparatorPlace::Back => infix.trim_right(),
383 SeparatorPlace::Front => infix.trim_left(),
385 if separator_place == SeparatorPlace::Front {
386 rhs_shape = try_opt!(rhs_shape.offset_left(infix.len()));
388 let rhs_result = try_opt!(rhs.rewrite(context, rhs_shape));
389 match separator_place {
390 SeparatorPlace::Back => Some(format!(
394 rhs_shape.indent.to_string(context.config),
398 SeparatorPlace::Front => Some(format!(
401 rhs_shape.indent.to_string(context.config),
409 pub fn rewrite_array<'a, I>(
412 context: &RewriteContext,
414 trailing_comma: bool,
417 I: Iterator<Item = &'a ast::Expr>,
419 let bracket_size = if context.config.spaces_within_square_brackets() {
425 let nested_shape = match context.config.array_layout() {
426 IndentStyle::Block => try_opt!(
429 .block_indent(context.config.tab_spaces())
430 .with_max_width(context.config)
433 IndentStyle::Visual => try_opt!(
435 .visual_indent(bracket_size)
436 .sub_width(bracket_size * 2)
440 let items = itemize_list(
444 |item| item.span.lo(),
445 |item| item.span.hi(),
446 |item| item.rewrite(context, nested_shape),
450 ).collect::<Vec<_>>();
452 if items.is_empty() {
453 if context.config.spaces_within_square_brackets() {
454 return Some("[ ]".to_string());
456 return Some("[]".to_string());
460 let has_long_item = items
462 .any(|li| li.item.as_ref().map(|s| s.len() > 10).unwrap_or(false));
464 let mut tactic = match context.config.array_layout() {
465 IndentStyle::Block => {
466 // FIXME wrong shape in one-line case
467 match shape.width.checked_sub(2 * bracket_size) {
470 ListTactic::LimitedHorizontalVertical(context.config.array_width());
471 definitive_tactic(&items, tactic, Separator::Comma, width)
473 None => DefinitiveListTactic::Vertical,
476 IndentStyle::Visual => if has_long_item || items.iter().any(ListItem::is_multiline) {
479 ListTactic::LimitedHorizontalVertical(context.config.array_width()),
484 DefinitiveListTactic::Mixed
487 let ends_with_newline = tactic.ends_with_newline(context.config.array_layout());
488 if context.config.array_horizontal_layout_threshold() > 0
489 && items.len() > context.config.array_horizontal_layout_threshold()
491 tactic = DefinitiveListTactic::Mixed;
494 let fmt = ListFormatting {
497 trailing_separator: if trailing_comma {
498 SeparatorTactic::Always
499 } else if context.inside_macro || context.config.array_layout() == IndentStyle::Visual {
500 SeparatorTactic::Never
502 SeparatorTactic::Vertical
504 separator_place: SeparatorPlace::Back,
506 ends_with_newline: ends_with_newline,
507 preserve_newline: false,
508 config: context.config,
510 let list_str = try_opt!(write_list(&items, &fmt));
512 let result = if context.config.array_layout() == IndentStyle::Visual
513 || tactic == DefinitiveListTactic::Horizontal
515 if context.config.spaces_within_square_brackets() && !list_str.is_empty() {
516 format!("[ {} ]", list_str)
518 format!("[{}]", list_str)
523 nested_shape.indent.to_string(context.config),
525 shape.block().indent.to_string(context.config)
532 // Return type is (prefix, extra_offset)
533 fn rewrite_closure_fn_decl(
534 capture: ast::CaptureBy,
535 fn_decl: &ast::FnDecl,
538 context: &RewriteContext,
540 ) -> Option<(String, usize)> {
541 let mover = if capture == ast::CaptureBy::Value {
546 // 4 = "|| {".len(), which is overconservative when the closure consists of
547 // a single expression.
548 let nested_shape = try_opt!(try_opt!(shape.shrink_left(mover.len())).sub_width(4));
551 let argument_offset = nested_shape.indent + 1;
552 let arg_shape = try_opt!(nested_shape.offset_left(1)).visual_indent(0);
553 let ret_str = try_opt!(fn_decl.output.rewrite(context, arg_shape));
555 let arg_items = itemize_list(
557 fn_decl.inputs.iter(),
559 |arg| span_lo_for_arg(arg),
560 |arg| span_hi_for_arg(context, arg),
561 |arg| arg.rewrite(context, arg_shape),
562 context.codemap.span_after(span, "|"),
566 let item_vec = arg_items.collect::<Vec<_>>();
567 // 1 = space between arguments and return type.
568 let horizontal_budget = nested_shape
570 .checked_sub(ret_str.len() + 1)
572 let tactic = definitive_tactic(
574 ListTactic::HorizontalVertical,
578 let arg_shape = match tactic {
579 DefinitiveListTactic::Horizontal => try_opt!(arg_shape.sub_width(ret_str.len() + 1)),
583 let fmt = ListFormatting {
586 trailing_separator: SeparatorTactic::Never,
587 separator_place: SeparatorPlace::Back,
589 ends_with_newline: false,
590 preserve_newline: true,
591 config: context.config,
593 let list_str = try_opt!(write_list(&item_vec, &fmt));
594 let mut prefix = format!("{}|{}|", mover, list_str);
595 // 1 = space between `|...|` and body.
596 let extra_offset = extra_offset(&prefix, shape) + 1;
598 if !ret_str.is_empty() {
599 if prefix.contains('\n') {
601 prefix.push_str(&argument_offset.to_string(context.config));
605 prefix.push_str(&ret_str);
608 Some((prefix, extra_offset))
611 // This functions is pretty messy because of the rules around closures and blocks:
612 // FIXME - the below is probably no longer true in full.
613 // * if there is a return type, then there must be braces,
614 // * given a closure with braces, whether that is parsed to give an inner block
615 // or not depends on if there is a return type and if there are statements
617 // * if the first expression in the body ends with a block (i.e., is a
618 // statement without needing a semi-colon), then adding or removing braces
619 // can change whether it is treated as an expression or statement.
621 capture: ast::CaptureBy,
622 fn_decl: &ast::FnDecl,
625 context: &RewriteContext,
627 ) -> Option<String> {
628 let (prefix, extra_offset) = try_opt!(rewrite_closure_fn_decl(
636 // 1 = space between `|...|` and body.
637 let body_shape = try_opt!(shape.offset_left(extra_offset));
639 if let ast::ExprKind::Block(ref block) = body.node {
640 // The body of the closure is an empty block.
641 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) {
642 return Some(format!("{} {{}}", prefix));
645 // Figure out if the block is necessary.
646 let needs_block = block.rules != ast::BlockCheckMode::Default || block.stmts.len() > 1
647 || context.inside_macro
648 || block_contains_comment(block, context.codemap)
649 || prefix.contains('\n');
651 let no_return_type = if let ast::FunctionRetTy::Default(_) = fn_decl.output {
656 if no_return_type && !needs_block {
657 // block.stmts.len() == 1
658 if let Some(expr) = stmt_expr(&block.stmts[0]) {
659 if let Some(rw) = rewrite_closure_expr(expr, &prefix, context, body_shape) {
665 // Either we require a block, or tried without and failed.
666 rewrite_closure_block(block, &prefix, context, body_shape)
668 rewrite_closure_expr(body, &prefix, context, body_shape).or_else(|| {
669 // The closure originally had a non-block expression, but we can't fit on
670 // one line, so we'll insert a block.
671 rewrite_closure_with_block(context, body_shape, &prefix, body)
676 // Rewrite closure with a single expression wrapping its body with block.
677 fn rewrite_closure_with_block(
678 context: &RewriteContext,
682 ) -> Option<String> {
683 let block = ast::Block {
686 id: ast::NodeId::new(0),
687 node: ast::StmtKind::Expr(ptr::P(body.clone())),
691 id: ast::NodeId::new(0),
692 rules: ast::BlockCheckMode::Default,
695 rewrite_closure_block(&block, prefix, context, shape)
698 // Rewrite closure with a single expression without wrapping its body with block.
699 fn rewrite_closure_expr(
702 context: &RewriteContext,
704 ) -> Option<String> {
705 let mut rewrite = expr.rewrite(context, shape);
706 if classify::expr_requires_semi_to_be_stmt(left_most_sub_expr(expr)) {
707 rewrite = and_one_line(rewrite);
709 rewrite = rewrite.and_then(|rw| {
710 if context.config.multiline_closure_forces_block() && rw.contains('\n') {
716 rewrite.map(|rw| format!("{} {}", prefix, rw))
719 // Rewrite closure whose body is block.
720 fn rewrite_closure_block(
723 context: &RewriteContext,
725 ) -> Option<String> {
726 // Start with visual indent, then fall back to block indent if the
728 let block_threshold = context.config.closure_block_indent_threshold();
729 if block_threshold >= 0 {
730 if let Some(block_str) = block.rewrite(context, shape) {
731 if block_str.matches('\n').count() <= block_threshold as usize
732 && !need_block_indent(&block_str, shape)
734 if let Some(block_str) = block_str.rewrite(context, shape) {
735 return Some(format!("{} {}", prefix, block_str));
741 // The body of the closure is big enough to be block indented, that
742 // means we must re-format.
743 let block_shape = shape.block();
744 let block_str = try_opt!(block.rewrite(context, block_shape));
745 Some(format!("{} {}", prefix, block_str))
748 fn and_one_line(x: Option<String>) -> Option<String> {
749 x.and_then(|x| if x.contains('\n') { None } else { Some(x) })
752 fn nop_block_collapse(block_str: Option<String>, budget: usize) -> Option<String> {
753 debug!("nop_block_collapse {:?} {}", block_str, budget);
754 block_str.map(|block_str| {
755 if block_str.starts_with('{') && budget >= 2
756 && (block_str[1..].find(|c: char| !c.is_whitespace()).unwrap() == block_str.len() - 2)
765 fn rewrite_empty_block(
766 context: &RewriteContext,
769 ) -> Option<String> {
770 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) && shape.width >= 2
772 return Some("{}".to_owned());
775 // If a block contains only a single-line comment, then leave it on one line.
776 let user_str = context.snippet(block.span);
777 let user_str = user_str.trim();
778 if user_str.starts_with('{') && user_str.ends_with('}') {
779 let comment_str = user_str[1..user_str.len() - 1].trim();
780 if block.stmts.is_empty() && !comment_str.contains('\n') && !comment_str.starts_with("//")
781 && comment_str.len() + 4 <= shape.width
783 return Some(format!("{{ {} }}", comment_str));
790 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
791 Some(match block.rules {
792 ast::BlockCheckMode::Unsafe(..) => {
793 let snippet = context.snippet(block.span);
794 let open_pos = try_opt!(snippet.find_uncommented("{"));
795 // Extract comment between unsafe and block start.
796 let trimmed = &snippet[6..open_pos].trim();
798 if !trimmed.is_empty() {
799 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
800 let budget = try_opt!(shape.width.checked_sub(9));
803 try_opt!(rewrite_comment(
806 Shape::legacy(budget, shape.indent + 7),
814 ast::BlockCheckMode::Default => String::new(),
818 fn rewrite_single_line_block(
819 context: &RewriteContext,
823 ) -> Option<String> {
824 if is_simple_block(block, context.codemap) {
825 let expr_shape = Shape::legacy(shape.width - prefix.len(), shape.indent);
826 let expr_str = try_opt!(block.stmts[0].rewrite(context, expr_shape));
827 let result = format!("{}{{ {} }}", prefix, expr_str);
828 if result.len() <= shape.width && !result.contains('\n') {
835 fn rewrite_block_with_visitor(
836 context: &RewriteContext,
840 ) -> Option<String> {
841 if let rw @ Some(_) = rewrite_empty_block(context, block, shape) {
845 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
846 visitor.block_indent = shape.indent;
847 visitor.is_if_else_block = context.is_if_else_block;
849 ast::BlockCheckMode::Unsafe(..) => {
850 let snippet = context.snippet(block.span);
851 let open_pos = try_opt!(snippet.find_uncommented("{"));
852 visitor.last_pos = block.span.lo() + BytePos(open_pos as u32)
854 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo(),
857 visitor.visit_block(block, None);
858 Some(format!("{}{}", prefix, visitor.buffer))
861 impl Rewrite for ast::Block {
862 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
863 // shape.width is used only for the single line case: either the empty block `{}`,
864 // or an unsafe expression `unsafe { e }`.
865 if let rw @ Some(_) = rewrite_empty_block(context, self, shape) {
869 let prefix = try_opt!(block_prefix(context, self, shape));
871 let result = rewrite_block_with_visitor(context, &prefix, self, shape);
872 if let Some(ref result_str) = result {
873 if result_str.lines().count() <= 3 {
874 if let rw @ Some(_) = rewrite_single_line_block(context, &prefix, self, shape) {
884 impl Rewrite for ast::Stmt {
885 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
886 skip_out_of_file_lines_range!(context, self.span());
888 let result = match self.node {
889 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
890 ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
891 let suffix = if semicolon_for_stmt(context, self) {
897 let shape = try_opt!(shape.sub_width(suffix.len()));
898 format_expr(ex, ExprType::Statement, context, shape).map(|s| s + suffix)
900 ast::StmtKind::Mac(..) | ast::StmtKind::Item(..) => None,
902 result.and_then(|res| recover_comment_removed(res, self.span(), context))
906 // Rewrite condition if the given expression has one.
907 fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
909 ast::ExprKind::Match(ref cond, _) => {
911 let cond_shape = match context.config.control_style() {
912 Style::Legacy => try_opt!(shape.shrink_left(6).and_then(|s| s.sub_width(2))),
913 Style::Rfc => try_opt!(shape.offset_left(8)),
915 cond.rewrite(context, cond_shape)
917 ast::ExprKind::Block(ref block) if block.stmts.len() == 1 => {
918 stmt_expr(&block.stmts[0]).and_then(|e| rewrite_cond(context, e, shape))
920 _ => to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
922 String::from("\n") + &shape.indent.block_only().to_string(context.config);
924 .rewrite_cond(context, shape, &alt_block_sep)
925 .and_then(|rw| Some(rw.0))
930 // Abstraction over control flow expressions
932 struct ControlFlow<'a> {
933 cond: Option<&'a ast::Expr>,
934 block: &'a ast::Block,
935 else_block: Option<&'a ast::Expr>,
936 label: Option<ast::SpannedIdent>,
937 pat: Option<&'a ast::Pat>,
941 allow_single_line: bool,
942 // True if this is an `if` expression in an `else if` :-( hacky
947 fn to_control_flow<'a>(expr: &'a ast::Expr, expr_type: ExprType) -> Option<ControlFlow<'a>> {
949 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => Some(ControlFlow::new_if(
953 else_block.as_ref().map(|e| &**e),
954 expr_type == ExprType::SubExpression,
958 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
959 Some(ControlFlow::new_if(
963 else_block.as_ref().map(|e| &**e),
964 expr_type == ExprType::SubExpression,
969 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
970 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
972 ast::ExprKind::Loop(ref block, label) => {
973 Some(ControlFlow::new_loop(block, label, expr.span))
975 ast::ExprKind::While(ref cond, ref block, label) => {
976 Some(ControlFlow::new_while(None, cond, block, label, expr.span))
978 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => Some(
979 ControlFlow::new_while(Some(pat), cond, block, label, expr.span),
985 impl<'a> ControlFlow<'a> {
988 pat: Option<&'a ast::Pat>,
989 block: &'a ast::Block,
990 else_block: Option<&'a ast::Expr>,
991 allow_single_line: bool,
994 ) -> ControlFlow<'a> {
998 else_block: else_block,
1002 matcher: match pat {
1007 allow_single_line: allow_single_line,
1008 nested_if: nested_if,
1014 block: &'a ast::Block,
1015 label: Option<ast::SpannedIdent>,
1017 ) -> ControlFlow<'a> {
1027 allow_single_line: false,
1034 pat: Option<&'a ast::Pat>,
1035 cond: &'a ast::Expr,
1036 block: &'a ast::Block,
1037 label: Option<ast::SpannedIdent>,
1039 ) -> ControlFlow<'a> {
1047 matcher: match pat {
1052 allow_single_line: false,
1060 cond: &'a ast::Expr,
1061 block: &'a ast::Block,
1062 label: Option<ast::SpannedIdent>,
1064 ) -> ControlFlow<'a> {
1074 allow_single_line: false,
1080 fn rewrite_single_line(
1083 context: &RewriteContext,
1085 ) -> Option<String> {
1086 assert!(self.allow_single_line);
1087 let else_block = try_opt!(self.else_block);
1088 let fixed_cost = self.keyword.len() + " { } else { }".len();
1090 if let ast::ExprKind::Block(ref else_node) = else_block.node {
1091 if !is_simple_block(self.block, context.codemap)
1092 || !is_simple_block(else_node, context.codemap)
1093 || pat_expr_str.contains('\n')
1098 let new_width = try_opt!(width.checked_sub(pat_expr_str.len() + fixed_cost));
1099 let expr = &self.block.stmts[0];
1100 let if_str = try_opt!(expr.rewrite(context, Shape::legacy(new_width, Indent::empty())));
1102 let new_width = try_opt!(new_width.checked_sub(if_str.len()));
1103 let else_expr = &else_node.stmts[0];
1105 try_opt!(else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty())));
1107 if if_str.contains('\n') || else_str.contains('\n') {
1111 let result = format!(
1112 "{} {} {{ {} }} else {{ {} }}",
1119 if result.len() <= width {
1120 return Some(result);
1128 impl<'a> ControlFlow<'a> {
1131 context: &RewriteContext,
1133 alt_block_sep: &str,
1134 ) -> Option<(String, usize)> {
1135 // Do not take the rhs overhead from the upper expressions into account
1136 // when rewriting pattern.
1137 let new_width = context
1140 .checked_sub(shape.used_width())
1142 let fresh_shape = Shape {
1146 let constr_shape = if self.nested_if {
1147 // We are part of an if-elseif-else chain. Our constraints are tightened.
1148 // 7 = "} else " .len()
1149 try_opt!(fresh_shape.offset_left(7))
1154 let label_string = rewrite_label(self.label);
1155 // 1 = space after keyword.
1156 let offset = self.keyword.len() + label_string.len() + 1;
1158 let pat_expr_string = match self.cond {
1160 let cond_shape = match context.config.control_style() {
1161 Style::Legacy => try_opt!(constr_shape.shrink_left(offset)),
1162 Style::Rfc => try_opt!(constr_shape.offset_left(offset)),
1164 try_opt!(rewrite_pat_expr(
1174 None => String::new(),
1177 let brace_overhead =
1178 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
1184 let one_line_budget = context
1187 .checked_sub(constr_shape.used_width() + offset + brace_overhead)
1189 let force_newline_brace = context.config.control_style() == Style::Rfc
1190 && (pat_expr_string.contains('\n') || pat_expr_string.len() > one_line_budget)
1191 && !last_line_extendable(&pat_expr_string);
1193 // Try to format if-else on single line.
1194 if self.allow_single_line && context.config.single_line_if_else_max_width() > 0 {
1195 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
1197 if let Some(cond_str) = trial {
1198 if cond_str.len() <= context.config.single_line_if_else_max_width() {
1199 return Some((cond_str, 0));
1204 let cond_span = if let Some(cond) = self.cond {
1207 mk_sp(self.block.span.lo(), self.block.span.lo())
1210 // `for event in event`
1211 // Do not include label in the span.
1212 let lo = self.label.map_or(self.span.lo(), |label| label.span.hi());
1213 let between_kwd_cond = mk_sp(
1216 .span_after(mk_sp(lo, self.span.hi()), self.keyword.trim()),
1218 .map_or(cond_span.lo(), |p| if self.matcher.is_empty() {
1221 context.codemap.span_before(self.span, self.matcher.trim())
1225 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
1227 let after_cond_comment =
1228 extract_comment(mk_sp(cond_span.hi(), self.block.span.lo()), context, shape);
1230 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
1232 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine
1233 || force_newline_brace
1240 let used_width = if pat_expr_string.contains('\n') {
1241 last_line_width(&pat_expr_string)
1243 // 2 = spaces after keyword and condition.
1244 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
1252 between_kwd_cond_comment.as_ref().map_or(
1253 if pat_expr_string.is_empty() || pat_expr_string.starts_with('\n') {
1261 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
1268 impl<'a> Rewrite for ControlFlow<'a> {
1269 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1270 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
1273 String::from("\n") + &shape.indent.block_only().to_string(context.config);
1274 let (cond_str, used_width) = try_opt!(self.rewrite_cond(context, shape, &alt_block_sep));
1275 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
1276 if used_width == 0 {
1277 return Some(cond_str);
1280 let block_width = shape.width.checked_sub(used_width).unwrap_or(0);
1281 // This is used only for the empty block case: `{}`. So, we use 1 if we know
1282 // we should avoid the single line case.
1283 let block_width = if self.else_block.is_some() || self.nested_if {
1288 let block_shape = Shape {
1292 let mut block_context = context.clone();
1293 block_context.is_if_else_block = self.else_block.is_some();
1294 let block_str = try_opt!(rewrite_block_with_visitor(
1301 let mut result = format!("{}{}", cond_str, block_str);
1303 if let Some(else_block) = self.else_block {
1304 let shape = Shape::indented(shape.indent, context.config);
1305 let mut last_in_chain = false;
1306 let rewrite = match else_block.node {
1307 // If the else expression is another if-else expression, prevent it
1308 // from being formatted on a single line.
1309 // Note how we're passing the original shape, as the
1310 // cost of "else" should not cascade.
1311 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1312 ControlFlow::new_if(
1316 next_else_block.as_ref().map(|e| &**e),
1319 mk_sp(else_block.span.lo(), self.span.hi()),
1320 ).rewrite(context, shape)
1322 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1323 ControlFlow::new_if(
1327 next_else_block.as_ref().map(|e| &**e),
1330 mk_sp(else_block.span.lo(), self.span.hi()),
1331 ).rewrite(context, shape)
1334 last_in_chain = true;
1335 // When rewriting a block, the width is only used for single line
1336 // blocks, passing 1 lets us avoid that.
1337 let else_shape = Shape {
1338 width: min(1, shape.width),
1341 format_expr(else_block, ExprType::Statement, context, else_shape)
1345 let between_kwd_else_block = mk_sp(
1346 self.block.span.hi(),
1349 .span_before(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1351 let between_kwd_else_block_comment =
1352 extract_comment(between_kwd_else_block, context, shape);
1354 let after_else = mk_sp(
1357 .span_after(mk_sp(self.block.span.hi(), else_block.span.lo()), "else"),
1358 else_block.span.lo(),
1360 let after_else_comment = extract_comment(after_else, context, shape);
1362 let between_sep = match context.config.control_brace_style() {
1363 ControlBraceStyle::AlwaysNextLine | ControlBraceStyle::ClosingNextLine => {
1366 ControlBraceStyle::AlwaysSameLine => " ",
1368 let after_sep = match context.config.control_brace_style() {
1369 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1376 between_kwd_else_block_comment
1378 .map_or(between_sep, |s| &**s),
1379 after_else_comment.as_ref().map_or(after_sep, |s| &**s)
1382 result.push_str(&try_opt!(rewrite));
1389 fn rewrite_label(label: Option<ast::SpannedIdent>) -> Cow<'static, str> {
1391 Some(ident) => Cow::from(format!("{}: ", ident.node)),
1392 None => Cow::from(""),
1396 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1397 match rewrite_missing_comment(span, shape, context) {
1398 Some(ref comment) if !comment.is_empty() => Some(format!(
1399 "\n{indent}{}\n{indent}",
1401 indent = shape.indent.to_string(context.config)
1407 fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool {
1408 let snippet = codemap.span_to_snippet(block.span).unwrap();
1409 contains_comment(&snippet)
1412 // Checks that a block contains no statements, an expression and no comments.
1413 // FIXME: incorrectly returns false when comment is contained completely within
1415 pub fn is_simple_block(block: &ast::Block, codemap: &CodeMap) -> bool {
1416 (block.stmts.len() == 1 && stmt_is_expr(&block.stmts[0])
1417 && !block_contains_comment(block, codemap))
1420 /// Checks whether a block contains at most one statement or expression, and no comments.
1421 pub fn is_simple_block_stmt(block: &ast::Block, codemap: &CodeMap) -> bool {
1422 block.stmts.len() <= 1 && !block_contains_comment(block, codemap)
1425 /// Checks whether a block contains no statements, expressions, or comments.
1426 pub fn is_empty_block(block: &ast::Block, codemap: &CodeMap) -> bool {
1427 block.stmts.is_empty() && !block_contains_comment(block, codemap)
1430 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1432 ast::StmtKind::Expr(..) => true,
1437 fn is_unsafe_block(block: &ast::Block) -> bool {
1438 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1445 // A simple wrapper type against ast::Arm. Used inside write_list().
1446 struct ArmWrapper<'a> {
1447 pub arm: &'a ast::Arm,
1448 // True if the arm is the last one in match expression. Used to decide on whether we should add
1449 // trailing comma to the match arm when `config.trailing_comma() == Never`.
1453 impl<'a> ArmWrapper<'a> {
1454 pub fn new(arm: &'a ast::Arm, is_last: bool) -> ArmWrapper<'a> {
1455 ArmWrapper { arm, is_last }
1459 impl<'a> Rewrite for ArmWrapper<'a> {
1460 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1461 rewrite_match_arm(context, self.arm, shape, self.is_last)
1466 context: &RewriteContext,
1471 attrs: &[ast::Attribute],
1472 ) -> Option<String> {
1473 if arms.is_empty() {
1477 // Do not take the rhs overhead from the upper expressions into account
1478 // when rewriting match condition.
1479 let new_width = try_opt!(context.config.max_width().checked_sub(shape.used_width()));
1480 let cond_shape = Shape {
1485 let cond_shape = match context.config.control_style() {
1486 Style::Legacy => try_opt!(cond_shape.shrink_left(6)),
1487 Style::Rfc => try_opt!(cond_shape.offset_left(6)),
1489 let cond_str = try_opt!(cond.rewrite(context, cond_shape));
1490 let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config);
1491 let block_sep = match context.config.control_brace_style() {
1492 ControlBraceStyle::AlwaysNextLine => &alt_block_sep,
1493 _ if last_line_extendable(&cond_str) => " ",
1495 _ if cond_str.contains('\n') || cond_str.len() + 2 > cond_shape.width => &alt_block_sep,
1499 let nested_indent_str = shape
1501 .block_indent(context.config)
1502 .to_string(context.config);
1503 // Inner attributes.
1504 let inner_attrs = &inner_attributes(attrs);
1505 let inner_attrs_str = if inner_attrs.is_empty() {
1510 .rewrite(context, shape)
1511 .map(|s| format!("{}{}\n", nested_indent_str, s))
1515 let open_brace_pos = if inner_attrs.is_empty() {
1518 .span_after(mk_sp(cond.span.hi(), arms[0].span().lo()), "{")
1520 inner_attrs[inner_attrs.len() - 1].span().hi()
1523 let arm_indent_str = if context.config.indent_match_arms() {
1526 shape.indent.to_string(context.config)
1530 "match {}{}{{\n{}{}{}\n{}}}",
1535 try_opt!(rewrite_match_arms(
1542 shape.indent.to_string(context.config),
1546 fn arm_comma(config: &Config, body: &ast::Expr, is_last: bool) -> &'static str {
1547 if is_last && config.trailing_comma() == SeparatorTactic::Never {
1549 } else if config.match_block_trailing_comma() {
1551 } else if let ast::ExprKind::Block(ref block) = body.node {
1552 if let ast::BlockCheckMode::Default = block.rules {
1562 fn rewrite_match_arms(
1563 context: &RewriteContext,
1567 open_brace_pos: BytePos,
1568 ) -> Option<String> {
1569 let arm_shape = if context.config.indent_match_arms() {
1570 shape.block_indent(context.config.tab_spaces())
1572 shape.block_indent(0)
1573 }.with_max_width(context.config);
1575 let arm_len = arms.len();
1576 let is_last_iter = repeat(false)
1577 .take(arm_len.checked_sub(1).unwrap_or(0))
1578 .chain(repeat(true));
1579 let items = itemize_list(
1583 .map(|(arm, is_last)| ArmWrapper::new(arm, is_last)),
1585 |arm| arm.arm.span().lo(),
1586 |arm| arm.arm.span().hi(),
1587 |arm| arm.rewrite(context, arm_shape),
1592 let arms_vec: Vec<_> = items.collect();
1593 let fmt = ListFormatting {
1594 tactic: DefinitiveListTactic::Vertical,
1595 // We will add/remove commas inside `arm.rewrite()`, and hence no separator here.
1597 trailing_separator: SeparatorTactic::Never,
1598 separator_place: SeparatorPlace::Back,
1600 ends_with_newline: true,
1601 preserve_newline: true,
1602 config: context.config,
1605 write_list(&arms_vec, &fmt)
1608 fn rewrite_match_arm(
1609 context: &RewriteContext,
1613 ) -> Option<String> {
1614 let (missing_span, attrs_str) = if !arm.attrs.is_empty() {
1615 if contains_skip(&arm.attrs) {
1616 let (_, body) = flatten_arm_body(context, &arm.body);
1617 // `arm.span()` does not include trailing comma, add it manually.
1618 return Some(format!(
1620 context.snippet(arm.span()),
1621 arm_comma(context.config, body, is_last),
1626 arm.attrs[arm.attrs.len() - 1].span.hi(),
1627 arm.pats[0].span.lo(),
1629 try_opt!(arm.attrs.rewrite(context, shape)),
1632 (mk_sp(arm.span().lo(), arm.span().lo()), String::new())
1634 let pats_str = try_opt!(
1635 rewrite_match_pattern(context, &arm.pats, &arm.guard, shape).and_then(|pats_str| {
1636 combine_strs_with_missing_comments(
1651 arm.guard.is_some(),
1656 fn rewrite_match_pattern(
1657 context: &RewriteContext,
1658 pats: &[ptr::P<ast::Pat>],
1659 guard: &Option<ptr::P<ast::Expr>>,
1661 ) -> Option<String> {
1664 let pat_shape = try_opt!(shape.sub_width(5));
1666 let pat_strs = try_opt!(
1668 .map(|p| p.rewrite(context, pat_shape))
1669 .collect::<Option<Vec<_>>>()
1672 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1673 let tactic = definitive_tactic(
1675 ListTactic::HorizontalVertical,
1676 Separator::VerticalBar,
1679 let fmt = ListFormatting {
1682 trailing_separator: SeparatorTactic::Never,
1683 separator_place: context.config.match_pattern_separator_break_point(),
1685 ends_with_newline: false,
1686 preserve_newline: false,
1687 config: context.config,
1689 let pats_str = try_opt!(write_list(&items, &fmt));
1692 let guard_str = try_opt!(rewrite_guard(
1696 trimmed_last_line_width(&pats_str),
1699 Some(format!("{}{}", pats_str, guard_str))
1703 // @extend: true if the arm body can be put next to `=>`
1704 // @body: flattened body, if the body is block with a single expression
1705 fn flatten_arm_body<'a>(context: &'a RewriteContext, body: &'a ast::Expr) -> (bool, &'a ast::Expr) {
1707 ast::ExprKind::Block(ref block)
1708 if !is_unsafe_block(block) && is_simple_block(block, context.codemap) =>
1710 if let ast::StmtKind::Expr(ref expr) = block.stmts[0].node {
1712 !context.config.multiline_match_arm_forces_block()
1713 && expr.can_be_overflowed(context, 1),
1721 !context.config.multiline_match_arm_forces_block()
1722 && body.can_be_overflowed(context, 1),
1728 fn rewrite_match_body(
1729 context: &RewriteContext,
1730 body: &ptr::P<ast::Expr>,
1735 ) -> Option<String> {
1736 let (extend, body) = flatten_arm_body(context, body);
1738 let comma = arm_comma(context.config, body, is_last);
1739 let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config);
1740 let alt_block_sep = alt_block_sep.as_str();
1741 let (is_block, is_empty_block) = if let ast::ExprKind::Block(ref block) = body.node {
1742 (true, is_empty_block(block, context.codemap))
1747 let combine_orig_body = |body_str: &str| {
1748 let block_sep = match context.config.control_brace_style() {
1749 ControlBraceStyle::AlwaysNextLine if is_block => alt_block_sep,
1753 Some(format!("{} =>{}{}{}", pats_str, block_sep, body_str, comma))
1756 let forbid_same_line = has_guard && pats_str.contains('\n') && !is_empty_block;
1757 let next_line_indent = if is_block {
1760 shape.indent.block_indent(context.config)
1762 let combine_next_line_body = |body_str: &str| {
1764 return Some(format!(
1767 next_line_indent.to_string(context.config),
1772 let indent_str = shape.indent.to_string(context.config);
1773 let nested_indent_str = next_line_indent.to_string(context.config);
1774 let (body_prefix, body_suffix) = if context.config.wrap_match_arms() {
1775 let comma = if context.config.match_block_trailing_comma() {
1780 ("{", format!("\n{}}}{}", indent_str, comma))
1782 ("", String::from(","))
1785 let block_sep = match context.config.control_brace_style() {
1786 ControlBraceStyle::AlwaysNextLine => format!("{}{}\n", alt_block_sep, body_prefix),
1787 _ if body_prefix.is_empty() => "\n".to_owned(),
1788 _ if forbid_same_line => format!("{}{}\n", alt_block_sep, body_prefix),
1789 _ => format!(" {}\n", body_prefix),
1790 } + &nested_indent_str;
1801 // Let's try and get the arm body on the same line as the condition.
1803 let orig_body_shape = shape
1804 .offset_left(extra_offset(pats_str, shape) + 4)
1805 .and_then(|shape| shape.sub_width(comma.len()));
1806 let orig_body = if let Some(body_shape) = orig_body_shape {
1807 let rewrite = nop_block_collapse(
1808 format_expr(body, ExprType::Statement, context, body_shape),
1814 if !forbid_same_line
1816 || (!body_str.contains('\n') && body_str.len() <= body_shape.width)) =>
1818 return combine_orig_body(body_str);
1825 let orig_budget = orig_body_shape.map_or(0, |shape| shape.width);
1827 // Try putting body on the next line and see if it looks better.
1828 let next_line_body_shape = Shape::indented(next_line_indent, context.config);
1829 let next_line_body = nop_block_collapse(
1830 format_expr(body, ExprType::Statement, context, next_line_body_shape),
1831 next_line_body_shape.width,
1833 match (orig_body, next_line_body) {
1834 (Some(ref orig_str), Some(ref next_line_str))
1835 if forbid_same_line || prefer_next_line(orig_str, next_line_str) =>
1837 combine_next_line_body(next_line_str)
1839 (Some(ref orig_str), _) if extend && first_line_width(orig_str) <= orig_budget => {
1840 combine_orig_body(orig_str)
1842 (Some(ref orig_str), Some(ref next_line_str)) if orig_str.contains('\n') => {
1843 combine_next_line_body(next_line_str)
1845 (None, Some(ref next_line_str)) => combine_next_line_body(next_line_str),
1846 (None, None) => None,
1847 (Some(ref orig_str), _) => combine_orig_body(orig_str),
1851 // The `if ...` guard on a match arm.
1853 context: &RewriteContext,
1854 guard: &Option<ptr::P<ast::Expr>>,
1856 // The amount of space used up on this line for the pattern in
1857 // the arm (excludes offset).
1858 pattern_width: usize,
1859 ) -> Option<String> {
1860 if let Some(ref guard) = *guard {
1861 // First try to fit the guard string on the same line as the pattern.
1862 // 4 = ` if `, 5 = ` => {`
1863 let cond_shape = shape
1864 .offset_left(pattern_width + 4)
1865 .and_then(|s| s.sub_width(5));
1866 if let Some(cond_shape) = cond_shape {
1867 if let Some(cond_str) = guard.rewrite(context, cond_shape) {
1868 if !cond_str.contains('\n') || pattern_width <= context.config.tab_spaces() {
1869 return Some(format!(" if {}", cond_str));
1874 // Not enough space to put the guard after the pattern, try a newline.
1875 // 3 = `if `, 5 = ` => {`
1876 let cond_shape = Shape::indented(shape.indent.block_indent(context.config), context.config)
1878 .and_then(|s| s.sub_width(5));
1879 if let Some(cond_shape) = cond_shape {
1880 if let Some(cond_str) = guard.rewrite(context, cond_shape) {
1881 return Some(format!(
1883 cond_shape.indent.to_string(context.config),
1895 fn rewrite_pat_expr(
1896 context: &RewriteContext,
1897 pat: Option<&ast::Pat>,
1900 // Connecting piece between pattern and expression,
1901 // *without* trailing space.
1905 ) -> Option<String> {
1906 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, pat, expr);
1907 if let Some(pat) = pat {
1908 let matcher = if matcher.is_empty() {
1911 format!("{} ", matcher)
1914 try_opt!(try_opt!(shape.offset_left(matcher.len())).sub_width(connector.len()));
1915 let pat_string = try_opt!(pat.rewrite(context, pat_shape));
1916 let result = format!("{}{}{}", matcher, pat_string, connector);
1917 return rewrite_assign_rhs(context, result, expr, shape);
1920 let expr_rw = expr.rewrite(context, shape);
1921 // The expression may (partially) fit on the current line.
1922 // We do not allow splitting between `if` and condition.
1923 if keyword == "if" || expr_rw.is_some() {
1927 // The expression won't fit on the current line, jump to next.
1928 let nested_shape = shape
1929 .block_indent(context.config.tab_spaces())
1930 .with_max_width(context.config);
1931 let nested_indent_str = nested_shape.indent.to_string(context.config);
1932 expr.rewrite(context, nested_shape)
1933 .map(|expr_rw| format!("\n{}{}", nested_indent_str, expr_rw))
1936 pub fn rewrite_literal(context: &RewriteContext, l: &ast::Lit, shape: Shape) -> Option<String> {
1938 ast::LitKind::Str(_, ast::StrStyle::Cooked) => rewrite_string_lit(context, l.span, shape),
1939 _ => Some(context.snippet(l.span)),
1943 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1944 let string_lit = context.snippet(span);
1946 if !context.config.format_strings() && !context.config.force_format_strings() {
1951 .all(|line| line.ends_with('\\'))
1953 let new_indent = shape.visual_indent(1).indent;
1954 return Some(String::from(
1960 new_indent.to_string(context.config),
1964 .collect::<Vec<_>>()
1969 return Some(string_lit);
1973 if !context.config.force_format_strings()
1974 && !string_requires_rewrite(context, span, &string_lit, shape)
1976 return Some(string_lit);
1979 // Remove the quote characters.
1980 let str_lit = &string_lit[1..string_lit.len() - 1];
1982 rewrite_string(str_lit, &StringFormat::new(shape, context.config))
1985 fn string_requires_rewrite(
1986 context: &RewriteContext,
1991 if context.codemap.lookup_char_pos(span.lo()).col.0 != shape.indent.width() {
1995 for (i, line) in string.lines().enumerate() {
1997 if line.len() > shape.width {
2000 } else if line.len() > shape.width + shape.indent.width() {
2008 pub fn rewrite_call(
2009 context: &RewriteContext,
2011 args: &[ptr::P<ast::Expr>],
2014 ) -> Option<String> {
2015 let force_trailing_comma = if context.inside_macro {
2016 span_ends_with_comma(context, span)
2023 &ptr_vec_to_ref_vec(&args),
2026 context.config.fn_call_width(),
2027 force_trailing_comma,
2031 pub fn rewrite_call_inner<'a, T>(
2032 context: &RewriteContext,
2037 args_max_width: usize,
2038 force_trailing_comma: bool,
2039 ) -> Result<String, Ordering>
2041 T: Rewrite + Spanned + ToExpr + 'a,
2043 // 2 = `( `, 1 = `(`
2044 let paren_overhead = if context.config.spaces_within_parens() {
2049 let used_width = extra_offset(callee_str, shape);
2050 let one_line_width = shape
2052 .checked_sub(used_width + 2 * paren_overhead)
2053 .ok_or(Ordering::Greater)?;
2055 let nested_shape = shape_from_fn_call_style(
2058 used_width + 2 * paren_overhead,
2059 used_width + paren_overhead,
2060 ).ok_or(Ordering::Greater)?;
2062 let span_lo = context.codemap.span_after(span, "(");
2063 let args_span = mk_sp(span_lo, span.hi());
2065 let (extendable, list_str) = rewrite_call_args(
2072 force_trailing_comma,
2073 ).ok_or(Ordering::Less)?;
2075 if !context.use_block_indent() && need_block_indent(&list_str, nested_shape) && !extendable {
2076 let mut new_context = context.clone();
2077 new_context.use_block = true;
2078 return rewrite_call_inner(
2085 force_trailing_comma,
2089 let args_shape = shape
2090 .sub_width(last_line_width(callee_str))
2091 .ok_or(Ordering::Less)?;
2095 wrap_args_with_parens(context, &list_str, extendable, args_shape, nested_shape)
2099 fn need_block_indent(s: &str, shape: Shape) -> bool {
2100 s.lines().skip(1).any(|s| {
2101 s.find(|c| !char::is_whitespace(c))
2102 .map_or(false, |w| w + 1 < shape.indent.width())
2106 fn rewrite_call_args<'a, T>(
2107 context: &RewriteContext,
2111 one_line_width: usize,
2112 args_max_width: usize,
2113 force_trailing_comma: bool,
2114 ) -> Option<(bool, String)>
2116 T: Rewrite + Spanned + ToExpr + 'a,
2118 let items = itemize_list(
2122 |item| item.span().lo(),
2123 |item| item.span().hi(),
2124 |item| item.rewrite(context, shape),
2129 let mut item_vec: Vec<_> = items.collect();
2131 // Try letting the last argument overflow to the next line with block
2132 // indentation. If its first line fits on one line with the other arguments,
2133 // we format the function arguments horizontally.
2134 let tactic = try_overflow_last_arg(
2143 let fmt = ListFormatting {
2146 trailing_separator: if force_trailing_comma {
2147 SeparatorTactic::Always
2148 } else if context.inside_macro || !context.use_block_indent() {
2149 SeparatorTactic::Never
2151 context.config.trailing_comma()
2153 separator_place: SeparatorPlace::Back,
2155 ends_with_newline: context.use_block_indent() && tactic == DefinitiveListTactic::Vertical,
2156 preserve_newline: false,
2157 config: context.config,
2160 write_list(&item_vec, &fmt).map(|args_str| {
2161 (tactic != DefinitiveListTactic::Vertical, args_str)
2165 fn try_overflow_last_arg<'a, T>(
2166 context: &RewriteContext,
2167 item_vec: &mut Vec<ListItem>,
2170 one_line_width: usize,
2171 args_max_width: usize,
2172 ) -> DefinitiveListTactic
2174 T: Rewrite + Spanned + ToExpr + 'a,
2176 let overflow_last = can_be_overflowed(context, args);
2178 // Replace the last item with its first line to see if it fits with
2180 let placeholder = if overflow_last {
2181 let mut context = context.clone();
2182 if let Some(expr) = args[args.len() - 1].to_expr() {
2183 if let ast::ExprKind::MethodCall(..) = expr.node {
2184 context.force_one_line_chain = true;
2187 last_arg_shape(&context, item_vec, shape, args_max_width).and_then(|arg_shape| {
2188 rewrite_last_arg_with_overflow(&context, args, &mut item_vec[args.len() - 1], arg_shape)
2194 let mut tactic = definitive_tactic(
2196 ListTactic::LimitedHorizontalVertical(args_max_width),
2201 // Replace the stub with the full overflowing last argument if the rewrite
2202 // succeeded and its first line fits with the other arguments.
2203 match (overflow_last, tactic, placeholder) {
2204 (true, DefinitiveListTactic::Horizontal, placeholder @ Some(..)) => {
2205 item_vec[args.len() - 1].item = placeholder;
2207 _ if args.len() >= 1 => {
2208 item_vec[args.len() - 1].item = args.last()
2209 .and_then(|last_arg| last_arg.rewrite(context, shape));
2210 // Use horizontal layout for a function with a single argument as long as
2211 // everything fits in a single line.
2213 && args_max_width != 0 // Vertical layout is forced.
2214 && !item_vec[0].has_comment()
2215 && !item_vec[0].inner_as_ref().contains('\n')
2216 && ::lists::total_item_width(&item_vec[0]) <= one_line_width
2218 tactic = DefinitiveListTactic::Horizontal;
2220 tactic = definitive_tactic(
2222 ListTactic::LimitedHorizontalVertical(args_max_width),
2235 context: &RewriteContext,
2238 args_max_width: usize,
2239 ) -> Option<Shape> {
2240 let overhead = items.iter().rev().skip(1).fold(0, |acc, i| {
2241 acc + i.item.as_ref().map_or(0, |s| first_line_width(s))
2243 let max_width = min(args_max_width, shape.width);
2244 let arg_indent = if context.use_block_indent() {
2245 shape.block().indent.block_unindent(context.config)
2247 shape.block().indent
2250 width: try_opt!(max_width.checked_sub(overhead)),
2256 // Rewriting closure which is placed at the end of the function call's arg.
2257 // Returns `None` if the reformatted closure 'looks bad'.
2258 fn rewrite_last_closure(
2259 context: &RewriteContext,
2262 ) -> Option<String> {
2263 if let ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) = expr.node {
2264 let body = match body.node {
2265 ast::ExprKind::Block(ref block) if block.stmts.len() == 1 => {
2266 stmt_expr(&block.stmts[0]).unwrap_or(body)
2270 let (prefix, extra_offset) = try_opt!(rewrite_closure_fn_decl(
2278 // If the closure goes multi line before its body, do not overflow the closure.
2279 if prefix.contains('\n') {
2282 let body_shape = try_opt!(shape.offset_left(extra_offset));
2283 // When overflowing the closure which consists of a single control flow expression,
2284 // force to use block if its condition uses multi line.
2285 let is_multi_lined_cond = rewrite_cond(context, body, body_shape)
2286 .map(|cond| cond.contains('\n') || cond.len() > body_shape.width)
2288 if is_multi_lined_cond {
2289 return rewrite_closure_with_block(context, body_shape, &prefix, body);
2292 // Seems fine, just format the closure in usual manner.
2293 return expr.rewrite(context, shape);
2298 fn rewrite_last_arg_with_overflow<'a, T>(
2299 context: &RewriteContext,
2301 last_item: &mut ListItem,
2305 T: Rewrite + Spanned + ToExpr + 'a,
2307 let last_arg = args[args.len() - 1];
2308 let rewrite = if let Some(expr) = last_arg.to_expr() {
2310 // When overflowing the closure which consists of a single control flow expression,
2311 // force to use block if its condition uses multi line.
2312 ast::ExprKind::Closure(..) => {
2313 // If the argument consists of multiple closures, we do not overflow
2314 // the last closure.
2319 .filter_map(|arg| arg.to_expr())
2320 .any(|expr| match expr.node {
2321 ast::ExprKind::Closure(..) => true,
2326 rewrite_last_closure(context, expr, shape)
2329 _ => expr.rewrite(context, shape),
2332 last_arg.rewrite(context, shape)
2335 if let Some(rewrite) = rewrite {
2336 let rewrite_first_line = Some(rewrite[..first_line_width(&rewrite)].to_owned());
2337 last_item.item = rewrite_first_line;
2344 fn can_be_overflowed<'a, T>(context: &RewriteContext, args: &[&T]) -> bool
2346 T: Rewrite + Spanned + ToExpr + 'a,
2349 .map_or(false, |x| x.can_be_overflowed(context, args.len()))
2352 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
2354 ast::ExprKind::Match(..) => {
2355 (context.use_block_indent() && args_len == 1)
2356 || (context.config.fn_call_style() == IndentStyle::Visual && args_len > 1)
2358 ast::ExprKind::If(..) |
2359 ast::ExprKind::IfLet(..) |
2360 ast::ExprKind::ForLoop(..) |
2361 ast::ExprKind::Loop(..) |
2362 ast::ExprKind::While(..) |
2363 ast::ExprKind::WhileLet(..) => {
2364 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
2366 ast::ExprKind::Block(..) | ast::ExprKind::Closure(..) => {
2367 context.use_block_indent()
2368 || context.config.fn_call_style() == IndentStyle::Visual && args_len > 1
2370 ast::ExprKind::Array(..) |
2371 ast::ExprKind::Call(..) |
2372 ast::ExprKind::Mac(..) |
2373 ast::ExprKind::MethodCall(..) |
2374 ast::ExprKind::Struct(..) |
2375 ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
2376 ast::ExprKind::AddrOf(_, ref expr) |
2377 ast::ExprKind::Box(ref expr) |
2378 ast::ExprKind::Try(ref expr) |
2379 ast::ExprKind::Unary(_, ref expr) |
2380 ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
2385 pub fn wrap_args_with_parens(
2386 context: &RewriteContext,
2388 is_extendable: bool,
2390 nested_shape: Shape,
2392 if !context.use_block_indent()
2393 || (context.inside_macro && !args_str.contains('\n')
2394 && args_str.len() + paren_overhead(context) <= shape.width) || is_extendable
2396 if context.config.spaces_within_parens() && !args_str.is_empty() {
2397 format!("( {} )", args_str)
2399 format!("({})", args_str)
2404 nested_shape.indent.to_string(context.config),
2406 shape.block().indent.to_string(context.config)
2411 fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
2412 let snippet = context.snippet(span);
2414 .trim_right_matches(|c: char| c == ')' || c.is_whitespace())
2418 fn rewrite_paren(context: &RewriteContext, subexpr: &ast::Expr, shape: Shape) -> Option<String> {
2419 debug!("rewrite_paren, shape: {:?}", shape);
2420 let total_paren_overhead = paren_overhead(context);
2421 let paren_overhead = total_paren_overhead / 2;
2422 let sub_shape = try_opt!(
2424 .offset_left(paren_overhead)
2425 .and_then(|s| s.sub_width(paren_overhead))
2428 let paren_wrapper = |s: &str| if context.config.spaces_within_parens() && !s.is_empty() {
2429 format!("( {} )", s)
2434 let subexpr_str = try_opt!(subexpr.rewrite(context, sub_shape));
2435 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
2437 if subexpr_str.contains('\n')
2438 || first_line_width(&subexpr_str) + total_paren_overhead <= shape.width
2440 Some(paren_wrapper(&subexpr_str))
2449 context: &RewriteContext,
2451 ) -> Option<String> {
2452 let expr_str = try_opt!(expr.rewrite(context, shape));
2454 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
2460 let offset = last_line_width(&expr_str) + lbr.len();
2461 let rhs_overhead = shape.rhs_overhead(context.config);
2462 let index_shape = if expr_str.contains('\n') {
2463 Shape::legacy(context.config.max_width(), shape.indent)
2464 .offset_left(offset)
2465 .and_then(|shape| shape.sub_width(rbr.len() + rhs_overhead))
2467 shape.visual_indent(offset).sub_width(offset + rbr.len())
2469 let orig_index_rw = index_shape.and_then(|s| index.rewrite(context, s));
2471 // Return if index fits in a single line.
2472 match orig_index_rw {
2473 Some(ref index_str) if !index_str.contains('\n') => {
2474 return Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr));
2479 // Try putting index on the next line and see if it fits in a single line.
2480 let indent = shape.indent.block_indent(context.config);
2481 let index_shape = try_opt!(Shape::indented(indent, context.config).offset_left(lbr.len()));
2482 let index_shape = try_opt!(index_shape.sub_width(rbr.len() + rhs_overhead));
2483 let new_index_rw = index.rewrite(context, index_shape);
2484 match (orig_index_rw, new_index_rw) {
2485 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => Some(format!(
2488 indent.to_string(context.config),
2493 (None, Some(ref new_index_str)) => Some(format!(
2496 indent.to_string(context.config),
2501 (Some(ref index_str), _) => Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr)),
2506 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: &Option<&ast::Expr>) -> bool {
2511 fields.iter().all(|field| !field.is_shorthand)
2514 fn rewrite_struct_lit<'a>(
2515 context: &RewriteContext,
2517 fields: &'a [ast::Field],
2518 base: Option<&'a ast::Expr>,
2521 ) -> Option<String> {
2522 debug!("rewrite_struct_lit: shape {:?}", shape);
2524 enum StructLitField<'a> {
2525 Regular(&'a ast::Field),
2526 Base(&'a ast::Expr),
2530 let path_shape = try_opt!(shape.sub_width(2));
2531 let path_str = try_opt!(rewrite_path(
2539 if fields.is_empty() && base.is_none() {
2540 return Some(format!("{} {{}}", path_str));
2543 // Foo { a: Foo } - indent is +3, width is -5.
2544 let (h_shape, v_shape) = try_opt!(struct_lit_shape(shape, context, path_str.len() + 3, 2));
2546 let one_line_width = h_shape.map_or(0, |shape| shape.width);
2547 let body_lo = context.codemap.span_after(span, "{");
2548 let fields_str = if struct_lit_can_be_aligned(fields, &base)
2549 && context.config.struct_field_align_threshold() > 0
2551 try_opt!(rewrite_with_alignment(
2555 mk_sp(body_lo, span.hi()),
2559 let field_iter = fields
2561 .map(StructLitField::Regular)
2562 .chain(base.into_iter().map(StructLitField::Base));
2564 let span_lo = |item: &StructLitField| match *item {
2565 StructLitField::Regular(field) => field.span().lo(),
2566 StructLitField::Base(expr) => {
2567 let last_field_hi = fields.last().map_or(span.lo(), |field| field.span.hi());
2568 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo()));
2569 let pos = snippet.find_uncommented("..").unwrap();
2570 last_field_hi + BytePos(pos as u32)
2573 let span_hi = |item: &StructLitField| match *item {
2574 StructLitField::Regular(field) => field.span().hi(),
2575 StructLitField::Base(expr) => expr.span.hi(),
2577 let rewrite = |item: &StructLitField| match *item {
2578 StructLitField::Regular(field) => {
2579 // The 1 taken from the v_budget is for the comma.
2580 rewrite_field(context, field, try_opt!(v_shape.sub_width(1)), 0)
2582 StructLitField::Base(expr) => {
2584 expr.rewrite(context, try_opt!(v_shape.offset_left(2)))
2585 .map(|s| format!("..{}", s))
2589 let items = itemize_list(
2600 let item_vec = items.collect::<Vec<_>>();
2602 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
2603 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
2604 let fmt = struct_lit_formatting(nested_shape, tactic, context, base.is_some());
2606 try_opt!(write_list(&item_vec, &fmt))
2609 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
2610 Some(format!("{} {{{}}}", path_str, fields_str))
2612 // FIXME if context.config.struct_lit_style() == Visual, but we run out
2613 // of space, we should fall back to BlockIndent.
2616 pub fn wrap_struct_field(
2617 context: &RewriteContext,
2620 nested_shape: Shape,
2621 one_line_width: usize,
2623 if context.config.struct_lit_style() == IndentStyle::Block
2624 && (fields_str.contains('\n')
2625 || context.config.struct_lit_multiline_style() == MultilineStyle::ForceMulti
2626 || fields_str.len() > one_line_width)
2630 nested_shape.indent.to_string(context.config),
2632 shape.indent.to_string(context.config)
2635 // One liner or visual indent.
2636 format!(" {} ", fields_str)
2640 pub fn struct_lit_field_separator(config: &Config) -> &str {
2642 config.space_before_struct_lit_field_colon(),
2643 config.space_after_struct_lit_field_colon(),
2647 pub fn rewrite_field(
2648 context: &RewriteContext,
2651 prefix_max_width: usize,
2652 ) -> Option<String> {
2653 if contains_skip(&field.attrs) {
2654 return Some(context.snippet(field.span()));
2656 let name = &field.ident.node.to_string();
2657 if field.is_shorthand {
2658 Some(name.to_string())
2660 let mut separator = String::from(struct_lit_field_separator(context.config));
2661 for _ in 0..prefix_max_width.checked_sub(name.len()).unwrap_or(0) {
2662 separator.push(' ');
2664 let overhead = name.len() + separator.len();
2665 let expr_shape = try_opt!(shape.offset_left(overhead));
2666 let expr = field.expr.rewrite(context, expr_shape);
2668 let mut attrs_str = try_opt!(field.attrs.rewrite(context, shape));
2669 if !attrs_str.is_empty() {
2670 attrs_str.push_str(&format!("\n{}", shape.indent.to_string(context.config)));
2674 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
2676 let expr_offset = shape.indent.block_indent(context.config);
2679 .rewrite(context, Shape::indented(expr_offset, context.config));
2685 expr_offset.to_string(context.config),
2694 fn shape_from_fn_call_style(
2695 context: &RewriteContext,
2699 ) -> Option<Shape> {
2700 if context.use_block_indent() {
2704 .block_indent(context.config.tab_spaces())
2705 .with_max_width(context.config)
2708 shape.visual_indent(offset).sub_width(overhead)
2712 fn rewrite_tuple_in_visual_indent_style<'a, T>(
2713 context: &RewriteContext,
2719 T: Rewrite + Spanned + ToExpr + 'a,
2721 let mut items = items.iter();
2722 // In case of length 1, need a trailing comma
2723 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
2724 if items.len() == 1 {
2726 let nested_shape = try_opt!(shape.sub_width(3)).visual_indent(1);
2727 return items.next().unwrap().rewrite(context, nested_shape).map(
2728 |s| if context.config.spaces_within_parens() {
2729 format!("( {}, )", s)
2736 let list_lo = context.codemap.span_after(span, "(");
2737 let nested_shape = try_opt!(shape.sub_width(2)).visual_indent(1);
2738 let items = itemize_list(
2742 |item| item.span().lo(),
2743 |item| item.span().hi(),
2744 |item| item.rewrite(context, nested_shape),
2746 span.hi() - BytePos(1),
2749 let item_vec: Vec<_> = items.collect();
2750 let tactic = definitive_tactic(
2752 ListTactic::HorizontalVertical,
2756 let fmt = ListFormatting {
2759 trailing_separator: SeparatorTactic::Never,
2760 separator_place: SeparatorPlace::Back,
2762 ends_with_newline: false,
2763 preserve_newline: false,
2764 config: context.config,
2766 let list_str = try_opt!(write_list(&item_vec, &fmt));
2768 if context.config.spaces_within_parens() && !list_str.is_empty() {
2769 Some(format!("( {} )", list_str))
2771 Some(format!("({})", list_str))
2775 pub fn rewrite_tuple<'a, T>(
2776 context: &RewriteContext,
2782 T: Rewrite + Spanned + ToExpr + 'a,
2784 debug!("rewrite_tuple {:?}", shape);
2785 if context.use_block_indent() {
2786 // We use the same rule as function calls for rewriting tuples.
2787 let force_trailing_comma = if context.inside_macro {
2788 span_ends_with_comma(context, span)
2798 context.config.fn_call_width(),
2799 force_trailing_comma,
2802 rewrite_tuple_in_visual_indent_style(context, items, span, shape)
2806 pub fn rewrite_unary_prefix<R: Rewrite>(
2807 context: &RewriteContext,
2811 ) -> Option<String> {
2813 .rewrite(context, try_opt!(shape.offset_left(prefix.len())))
2814 .map(|r| format!("{}{}", prefix, r))
2817 // FIXME: this is probably not correct for multi-line Rewrites. we should
2818 // subtract suffix.len() from the last line budget, not the first!
2819 pub fn rewrite_unary_suffix<R: Rewrite>(
2820 context: &RewriteContext,
2824 ) -> Option<String> {
2826 .rewrite(context, try_opt!(shape.sub_width(suffix.len())))
2833 fn rewrite_unary_op(
2834 context: &RewriteContext,
2838 ) -> Option<String> {
2839 // For some reason, an UnOp is not spanned like BinOp!
2840 let operator_str = match *op {
2841 ast::UnOp::Deref => "*",
2842 ast::UnOp::Not => "!",
2843 ast::UnOp::Neg => "-",
2845 rewrite_unary_prefix(context, operator_str, expr, shape)
2848 fn rewrite_assignment(
2849 context: &RewriteContext,
2852 op: Option<&ast::BinOp>,
2854 ) -> Option<String> {
2855 let operator_str = match op {
2856 Some(op) => context.snippet(op.span),
2857 None => "=".to_owned(),
2860 // 1 = space between lhs and operator.
2861 let lhs_shape = try_opt!(shape.sub_width(operator_str.len() + 1));
2862 let lhs_str = format!(
2864 try_opt!(lhs.rewrite(context, lhs_shape)),
2868 rewrite_assign_rhs(context, lhs_str, rhs, shape)
2871 // The left hand side must contain everything up to, and including, the
2872 // assignment operator.
2873 pub fn rewrite_assign_rhs<S: Into<String>>(
2874 context: &RewriteContext,
2878 ) -> Option<String> {
2879 let lhs = lhs.into();
2880 let last_line_width = last_line_width(&lhs) - if lhs.contains('\n') {
2881 shape.indent.width()
2885 // 1 = space between operator and rhs.
2886 let orig_shape = try_opt!(shape.offset_left(last_line_width + 1));
2887 let rhs = try_opt!(choose_rhs(
2891 ex.rewrite(context, orig_shape)
2897 context: &RewriteContext,
2900 orig_rhs: Option<String>,
2901 ) -> Option<String> {
2903 Some(ref new_str) if !new_str.contains('\n') => Some(format!(" {}", new_str)),
2905 // Expression did not fit on the same line as the identifier.
2906 // Try splitting the line and see if that works better.
2907 let new_shape = try_opt!(
2909 shape.block().indent.block_indent(context.config),
2911 ).sub_width(shape.rhs_overhead(context.config))
2913 let new_rhs = expr.rewrite(context, new_shape);
2914 let new_indent_str = &new_shape.indent.to_string(context.config);
2916 match (orig_rhs, new_rhs) {
2917 (Some(ref orig_rhs), Some(ref new_rhs)) if prefer_next_line(orig_rhs, new_rhs) => {
2918 Some(format!("\n{}{}", new_indent_str, new_rhs))
2920 (None, Some(ref new_rhs)) => Some(format!("\n{}{}", new_indent_str, new_rhs)),
2921 (None, None) => None,
2922 (Some(ref orig_rhs), _) => Some(format!(" {}", orig_rhs)),
2928 fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str) -> bool {
2929 fn count_line_breaks(src: &str) -> usize {
2930 src.chars().filter(|&x| x == '\n').count()
2933 !next_line_rhs.contains('\n')
2934 || count_line_breaks(orig_rhs) > count_line_breaks(next_line_rhs) + 1
2937 fn rewrite_expr_addrof(
2938 context: &RewriteContext,
2939 mutability: ast::Mutability,
2942 ) -> Option<String> {
2943 let operator_str = match mutability {
2944 ast::Mutability::Immutable => "&",
2945 ast::Mutability::Mutable => "&mut ",
2947 rewrite_unary_prefix(context, operator_str, expr, shape)
2951 fn to_expr(&self) -> Option<&ast::Expr>;
2952 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool;
2955 impl ToExpr for ast::Expr {
2956 fn to_expr(&self) -> Option<&ast::Expr> {
2960 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2961 can_be_overflowed_expr(context, self, len)
2965 impl ToExpr for ast::Ty {
2966 fn to_expr(&self) -> Option<&ast::Expr> {
2970 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2971 can_be_overflowed_type(context, self, len)
2975 impl<'a> ToExpr for TuplePatField<'a> {
2976 fn to_expr(&self) -> Option<&ast::Expr> {
2980 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
2981 can_be_overflowed_pat(context, self, len)
2985 impl<'a> ToExpr for ast::StructField {
2986 fn to_expr(&self) -> Option<&ast::Expr> {
2990 fn can_be_overflowed(&self, _: &RewriteContext, _: usize) -> bool {
2995 impl<'a> ToExpr for MacroArg {
2996 fn to_expr(&self) -> Option<&ast::Expr> {
2998 MacroArg::Expr(ref expr) => Some(expr),
3003 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
3005 MacroArg::Expr(ref expr) => can_be_overflowed_expr(context, expr, len),
3006 MacroArg::Ty(ref ty) => can_be_overflowed_type(context, ty, len),
3007 MacroArg::Pat(..) => false,