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::{Ordering, min};
12 use std::iter::ExactSizeIterator;
15 use {Indent, Shape, Spanned};
16 use codemap::SpanUtils;
17 use rewrite::{Rewrite, RewriteContext};
18 use lists::{write_list, itemize_list, ListFormatting, SeparatorTactic, ListTactic,
19 DefinitiveListTactic, definitive_tactic, ListItem, format_item_list, struct_lit_shape,
20 struct_lit_tactic, shape_for_tactic, struct_lit_formatting};
21 use string::{StringFormat, rewrite_string};
22 use utils::{extra_offset, last_line_width, wrap_str, binary_search, first_line_width,
23 semicolon_for_stmt, trimmed_last_line_width, left_most_sub_expr, stmt_expr,
24 colon_spaces, contains_skip, mk_sp, last_line_extendable};
25 use visitor::FmtVisitor;
26 use config::{Config, IndentStyle, MultilineStyle, ControlBraceStyle, Style};
27 use comment::{FindUncommented, rewrite_comment, contains_comment, recover_comment_removed};
28 use types::{rewrite_path, PathContext, can_be_overflowed_type};
29 use items::{span_lo_for_arg, span_hi_for_arg};
30 use chains::rewrite_chain;
31 use macros::{rewrite_macro, MacroPosition};
32 use patterns::{TuplePatField, can_be_overflowed_pat};
33 use vertical::rewrite_with_alignment;
35 use syntax::{ast, ptr};
36 use syntax::codemap::{CodeMap, Span, BytePos};
37 use syntax::parse::classify;
39 impl Rewrite for ast::Expr {
40 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
41 format_expr(self, ExprType::SubExpression, context, shape)
51 fn combine_attr_and_expr(
52 context: &RewriteContext,
57 let separator = if attr_str.is_empty() {
60 if expr_str.contains('\n') || attr_str.contains('\n') ||
61 attr_str.len() + expr_str.len() > shape.width
63 format!("\n{}", shape.indent.to_string(context.config))
68 format!("{}{}{}", attr_str, separator, expr_str)
74 context: &RewriteContext,
77 let attr_rw = (&*expr.attrs).rewrite(context, shape);
78 if contains_skip(&*expr.attrs) {
79 if let Some(attr_str) = attr_rw {
80 return Some(combine_attr_and_expr(
84 &context.snippet(expr.span),
87 return Some(context.snippet(expr.span));
90 let expr_rw = match expr.node {
91 ast::ExprKind::Array(ref expr_vec) => {
93 expr_vec.iter().map(|e| &**e),
94 mk_sp(context.codemap.span_after(expr.span, "["), expr.span.hi),
100 ast::ExprKind::Lit(ref l) => {
102 ast::LitKind::Str(_, ast::StrStyle::Cooked) => {
103 rewrite_string_lit(context, l.span, shape)
107 context.snippet(expr.span),
108 context.config.max_width(),
114 ast::ExprKind::Call(ref callee, ref args) => {
115 let inner_span = mk_sp(callee.span.hi, expr.span.hi);
116 rewrite_call_with_binary_search(
119 &args.iter().map(|x| &**x).collect::<Vec<_>>()[..],
124 ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape),
125 ast::ExprKind::Binary(ref op, ref lhs, ref rhs) => {
126 // FIXME: format comments between operands and operator
131 &format!(" {} ", context.snippet(op.span)),
137 ast::ExprKind::Unary(ref op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape),
138 ast::ExprKind::Struct(ref path, ref fields, ref base) => {
143 base.as_ref().map(|e| &**e),
148 ast::ExprKind::Tup(ref items) => {
151 &items.iter().map(|x| &**x).collect::<Vec<_>>()[..],
156 ast::ExprKind::If(..) |
157 ast::ExprKind::IfLet(..) |
158 ast::ExprKind::ForLoop(..) |
159 ast::ExprKind::Loop(..) |
160 ast::ExprKind::While(..) |
161 ast::ExprKind::WhileLet(..) => {
162 to_control_flow(expr, expr_type)
163 .and_then(|control_flow| control_flow.rewrite(context, shape))
165 ast::ExprKind::Block(ref block) => {
167 ExprType::Statement => {
168 if is_unsafe_block(block) {
169 block.rewrite(context, shape)
171 // Rewrite block without trying to put it in a single line.
172 if let rw @ Some(_) = rewrite_empty_block(context, block, shape) {
175 let prefix = try_opt!(block_prefix(context, block, shape));
176 rewrite_block_with_visitor(context, &prefix, block, shape)
179 ExprType::SubExpression => block.rewrite(context, shape),
182 ast::ExprKind::Match(ref cond, ref arms) => {
183 rewrite_match(context, cond, arms, shape, expr.span)
185 ast::ExprKind::Path(ref qself, ref path) => {
186 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
188 ast::ExprKind::Assign(ref lhs, ref rhs) => {
189 rewrite_assignment(context, lhs, rhs, None, shape)
191 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
192 rewrite_assignment(context, lhs, rhs, Some(op), shape)
194 ast::ExprKind::Continue(ref opt_ident) => {
195 let id_str = match *opt_ident {
196 Some(ident) => format!(" {}", ident.node),
197 None => String::new(),
200 format!("continue{}", id_str),
201 context.config.max_width(),
205 ast::ExprKind::Break(ref opt_ident, ref opt_expr) => {
206 let id_str = match *opt_ident {
207 Some(ident) => format!(" {}", ident.node),
208 None => String::new(),
211 if let Some(ref expr) = *opt_expr {
212 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
215 format!("break{}", id_str),
216 context.config.max_width(),
221 ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) => {
222 rewrite_closure(capture, fn_decl, body, expr.span, context, shape)
224 ast::ExprKind::Try(..) |
225 ast::ExprKind::Field(..) |
226 ast::ExprKind::TupField(..) |
227 ast::ExprKind::MethodCall(..) => rewrite_chain(expr, context, shape),
228 ast::ExprKind::Mac(ref mac) => {
229 // Failure to rewrite a marco should not imply failure to
230 // rewrite the expression.
231 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
233 context.snippet(expr.span),
234 context.config.max_width(),
239 ast::ExprKind::Ret(None) => {
240 wrap_str("return".to_owned(), context.config.max_width(), shape)
242 ast::ExprKind::Ret(Some(ref expr)) => {
243 rewrite_unary_prefix(context, "return ", &**expr, shape)
245 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
246 ast::ExprKind::AddrOf(mutability, ref expr) => {
247 rewrite_expr_addrof(context, mutability, expr, shape)
249 ast::ExprKind::Cast(ref expr, ref ty) => {
250 rewrite_pair(&**expr, &**ty, "", " as ", "", context, shape)
252 ast::ExprKind::Type(ref expr, ref ty) => {
253 rewrite_pair(&**expr, &**ty, "", ": ", "", context, shape)
255 ast::ExprKind::Index(ref expr, ref index) => {
256 rewrite_index(&**expr, &**index, context, shape)
258 ast::ExprKind::Repeat(ref expr, ref repeats) => {
259 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
264 rewrite_pair(&**expr, &**repeats, lbr, "; ", rbr, context, shape)
266 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
267 let delim = match limits {
268 ast::RangeLimits::HalfOpen => "..",
269 ast::RangeLimits::Closed => "...",
272 fn needs_space_before_range(context: &RewriteContext, lhs: &ast::Expr) -> bool {
274 ast::ExprKind::Lit(ref lit) => {
276 ast::LitKind::FloatUnsuffixed(..) => {
277 context.snippet(lit.span).ends_with('.')
286 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
287 (Some(ref lhs), Some(ref rhs)) => {
288 let sp_delim = if context.config.spaces_around_ranges() {
289 format!(" {} ", delim)
290 } else if needs_space_before_range(context, lhs) {
291 format!(" {}", delim)
295 rewrite_pair(&**lhs, &**rhs, "", &sp_delim, "", context, shape)
297 (None, Some(ref rhs)) => {
298 let sp_delim = if context.config.spaces_around_ranges() {
299 format!("{} ", delim)
303 rewrite_unary_prefix(context, &sp_delim, &**rhs, shape)
305 (Some(ref lhs), None) => {
306 let sp_delim = if context.config.spaces_around_ranges() {
307 format!(" {}", delim)
311 rewrite_unary_suffix(context, &sp_delim, &**lhs, shape)
313 (None, None) => wrap_str(delim.into(), context.config.max_width(), shape),
316 // We do not format these expressions yet, but they should still
317 // satisfy our width restrictions.
318 ast::ExprKind::InPlace(..) |
319 ast::ExprKind::InlineAsm(..) => {
321 context.snippet(expr.span),
322 context.config.max_width(),
326 ast::ExprKind::Catch(ref block) => {
327 if let rewrite @ Some(_) =
328 rewrite_single_line_block(context, "do catch ", block, shape)
333 let budget = shape.width.checked_sub(9).unwrap_or(0);
337 try_opt!(block.rewrite(&context, Shape::legacy(budget, shape.indent)))
341 match (attr_rw, expr_rw) {
342 (Some(attr_str), Some(expr_str)) => {
343 recover_comment_removed(
344 combine_attr_and_expr(context, shape, &attr_str, &expr_str),
354 pub fn rewrite_pair<LHS, RHS>(
360 context: &RewriteContext,
367 // Get "full width" rhs and see if it fits on the current line. This
368 // usually works fairly well since it tends to place operands of
369 // operations with high precendence close together.
370 // Note that this is non-conservative, but its just to see if it's even
371 // worth trying to put everything on one line.
372 let rhs_shape = try_opt!(shape.sub_width(suffix.len()));
373 let rhs_result = rhs.rewrite(context, rhs_shape);
375 if let Some(rhs_result) = rhs_result {
376 // This is needed in case of line break not caused by a
377 // shortage of space, but by end-of-line comments, for example.
378 if !rhs_result.contains('\n') {
380 try_opt!(try_opt!(shape.offset_left(prefix.len())).sub_width(infix.len()));
381 let lhs_result = lhs.rewrite(context, lhs_shape);
382 if let Some(lhs_result) = lhs_result {
383 let mut result = format!("{}{}{}", prefix, lhs_result, infix);
385 let remaining_width = shape
387 .checked_sub(last_line_width(&result) + suffix.len())
390 if rhs_result.len() <= remaining_width {
391 result.push_str(&rhs_result);
392 result.push_str(suffix);
396 // Try rewriting the rhs into the remaining space.
397 let rhs_shape = shape.shrink_left(last_line_width(&result) + suffix.len());
398 if let Some(rhs_shape) = rhs_shape {
399 if let Some(rhs_result) = rhs.rewrite(context, rhs_shape) {
400 // FIXME this should always hold.
401 if rhs_result.len() <= remaining_width {
402 result.push_str(&rhs_result);
403 result.push_str(suffix);
412 // We have to use multiple lines.
414 // Re-evaluate the rhs because we have more space now:
415 let infix = infix.trim_right();
416 let rhs_shape = match context.config.control_style() {
418 try_opt!(shape.sub_width(suffix.len() + prefix.len())).visual_indent(prefix.len())
421 // Try to calculate the initial constraint on the right hand side.
422 let rhs_overhead = context
425 .checked_sub(shape.used_width() + shape.width)
428 Shape::indented(shape.indent.block_indent(context.config), context.config)
429 .sub_width(rhs_overhead)
433 let rhs_result = try_opt!(rhs.rewrite(context, rhs_shape));
434 let lhs_overhead = shape.used_width() + prefix.len() + infix.len();
435 let lhs_shape = Shape {
436 width: try_opt!(context.config.max_width().checked_sub(lhs_overhead)),
439 let lhs_result = try_opt!(lhs.rewrite(context, lhs_shape));
445 rhs_shape.indent.to_string(context.config),
451 pub fn rewrite_array<'a, I>(
454 context: &RewriteContext,
456 trailing_comma: bool,
459 I: Iterator<Item = &'a ast::Expr>,
461 let bracket_size = if context.config.spaces_within_square_brackets() {
467 let nested_shape = match context.config.array_layout() {
468 IndentStyle::Block => shape.block().block_indent(context.config.tab_spaces()),
469 IndentStyle::Visual => {
472 .visual_indent(bracket_size)
473 .sub_width(bracket_size * 2)
478 let items = itemize_list(
484 |item| item.rewrite(context, nested_shape),
487 ).collect::<Vec<_>>();
489 if items.is_empty() {
490 if context.config.spaces_within_square_brackets() {
491 return Some("[ ]".to_string());
493 return Some("[]".to_string());
497 let has_long_item = items
499 .any(|li| li.item.as_ref().map(|s| s.len() > 10).unwrap_or(false));
501 let tactic = match context.config.array_layout() {
502 IndentStyle::Block => {
503 // FIXME wrong shape in one-line case
504 match shape.width.checked_sub(2 * bracket_size) {
507 ListTactic::LimitedHorizontalVertical(context.config.array_width());
508 definitive_tactic(&items, tactic, width)
510 None => DefinitiveListTactic::Vertical,
513 IndentStyle::Visual => {
514 if has_long_item || items.iter().any(ListItem::is_multiline) {
517 ListTactic::LimitedHorizontalVertical(context.config.array_width()),
521 DefinitiveListTactic::Mixed
526 let fmt = ListFormatting {
529 trailing_separator: if trailing_comma {
530 SeparatorTactic::Always
531 } else if context.inside_macro || context.config.array_layout() == IndentStyle::Visual {
532 SeparatorTactic::Never
534 SeparatorTactic::Vertical
537 ends_with_newline: false,
538 config: context.config,
540 let list_str = try_opt!(write_list(&items, &fmt));
542 let result = if context.config.array_layout() == IndentStyle::Visual ||
543 tactic != DefinitiveListTactic::Vertical
545 if context.config.spaces_within_square_brackets() && list_str.len() > 0 {
546 format!("[ {} ]", list_str)
548 format!("[{}]", list_str)
553 nested_shape.indent.to_string(context.config),
555 shape.block().indent.to_string(context.config)
562 // Return type is (prefix, extra_offset)
563 fn rewrite_closure_fn_decl(
564 capture: ast::CaptureBy,
565 fn_decl: &ast::FnDecl,
568 context: &RewriteContext,
570 ) -> Option<(String, usize)> {
571 let mover = if capture == ast::CaptureBy::Value {
576 // 4 = "|| {".len(), which is overconservative when the closure consists of
577 // a single expression.
578 let nested_shape = try_opt!(try_opt!(shape.shrink_left(mover.len())).sub_width(4));
581 let argument_offset = nested_shape.indent + 1;
582 let arg_shape = try_opt!(nested_shape.shrink_left(1)).visual_indent(0);
583 let ret_str = try_opt!(fn_decl.output.rewrite(context, arg_shape));
585 let arg_items = itemize_list(
587 fn_decl.inputs.iter(),
589 |arg| span_lo_for_arg(arg),
590 |arg| span_hi_for_arg(context, arg),
591 |arg| arg.rewrite(context, arg_shape),
592 context.codemap.span_after(span, "|"),
595 let item_vec = arg_items.collect::<Vec<_>>();
596 // 1 = space between arguments and return type.
597 let horizontal_budget = nested_shape
599 .checked_sub(ret_str.len() + 1)
601 let tactic = definitive_tactic(&item_vec, ListTactic::HorizontalVertical, horizontal_budget);
602 let arg_shape = match tactic {
603 DefinitiveListTactic::Horizontal => try_opt!(arg_shape.sub_width(ret_str.len() + 1)),
607 let fmt = ListFormatting {
610 trailing_separator: SeparatorTactic::Never,
612 ends_with_newline: false,
613 config: context.config,
615 let list_str = try_opt!(write_list(&item_vec, &fmt));
616 let mut prefix = format!("{}|{}|", mover, list_str);
617 // 1 = space between `|...|` and body.
618 let extra_offset = extra_offset(&prefix, shape) + 1;
620 if !ret_str.is_empty() {
621 if prefix.contains('\n') {
623 prefix.push_str(&argument_offset.to_string(context.config));
627 prefix.push_str(&ret_str);
630 Some((prefix, extra_offset))
633 // This functions is pretty messy because of the rules around closures and blocks:
634 // FIXME - the below is probably no longer true in full.
635 // * if there is a return type, then there must be braces,
636 // * given a closure with braces, whether that is parsed to give an inner block
637 // or not depends on if there is a return type and if there are statements
639 // * if the first expression in the body ends with a block (i.e., is a
640 // statement without needing a semi-colon), then adding or removing braces
641 // can change whether it is treated as an expression or statement.
643 capture: ast::CaptureBy,
644 fn_decl: &ast::FnDecl,
647 context: &RewriteContext,
649 ) -> Option<String> {
650 let (prefix, extra_offset) = try_opt!(rewrite_closure_fn_decl(
658 // 1 = space between `|...|` and body.
659 let body_shape = try_opt!(shape.offset_left(extra_offset));
661 if let ast::ExprKind::Block(ref block) = body.node {
662 // The body of the closure is an empty block.
663 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) {
664 return Some(format!("{} {{}}", prefix));
667 // Figure out if the block is necessary.
668 let needs_block = block.rules != ast::BlockCheckMode::Default ||
669 block.stmts.len() > 1 || context.inside_macro ||
670 block_contains_comment(block, context.codemap) ||
671 prefix.contains('\n');
673 let no_return_type = if let ast::FunctionRetTy::Default(_) = fn_decl.output {
678 if no_return_type && !needs_block {
679 // lock.stmts.len() == 1
680 if let Some(ref expr) = stmt_expr(&block.stmts[0]) {
681 if let Some(rw) = rewrite_closure_expr(expr, &prefix, context, body_shape) {
688 // We need braces, but we might still prefer a one-liner.
689 let stmt = &block.stmts[0];
690 // 4 = braces and spaces.
691 if let Some(body_shape) = body_shape.sub_width(4) {
692 // Checks if rewrite succeeded and fits on a single line.
693 if let Some(rewrite) = and_one_line(stmt.rewrite(context, body_shape)) {
694 return Some(format!("{} {{ {} }}", prefix, rewrite));
699 // Either we require a block, or tried without and failed.
700 rewrite_closure_block(&block, &prefix, context, body_shape)
702 rewrite_closure_expr(body, &prefix, context, body_shape).or_else(|| {
703 // The closure originally had a non-block expression, but we can't fit on
704 // one line, so we'll insert a block.
705 rewrite_closure_with_block(context, body_shape, &prefix, body)
710 // Rewrite closure with a single expression wrapping its body with block.
711 fn rewrite_closure_with_block(
712 context: &RewriteContext,
716 ) -> Option<String> {
717 let block = ast::Block {
720 id: ast::NodeId::new(0),
721 node: ast::StmtKind::Expr(ptr::P(body.clone())),
725 id: ast::NodeId::new(0),
726 rules: ast::BlockCheckMode::Default,
729 rewrite_closure_block(&block, prefix, context, shape)
732 // Rewrite closure with a single expression without wrapping its body with block.
733 fn rewrite_closure_expr(
736 context: &RewriteContext,
738 ) -> Option<String> {
739 let mut rewrite = expr.rewrite(context, shape);
740 if classify::expr_requires_semi_to_be_stmt(left_most_sub_expr(expr)) {
741 rewrite = and_one_line(rewrite);
743 rewrite.map(|rw| format!("{} {}", prefix, rw))
746 // Rewrite closure whose body is block.
747 fn rewrite_closure_block(
750 context: &RewriteContext,
752 ) -> Option<String> {
753 // Start with visual indent, then fall back to block indent if the
755 let block_threshold = context.config.closure_block_indent_threshold();
756 if block_threshold >= 0 {
757 if let Some(block_str) = block.rewrite(&context, shape) {
758 if block_str.matches('\n').count() <= block_threshold as usize &&
759 !need_block_indent(&block_str, shape)
761 if let Some(block_str) = block_str.rewrite(context, shape) {
762 return Some(format!("{} {}", prefix, block_str));
768 // The body of the closure is big enough to be block indented, that
769 // means we must re-format.
770 let block_shape = shape.block();
771 let block_str = try_opt!(block.rewrite(&context, block_shape));
772 Some(format!("{} {}", prefix, block_str))
775 fn and_one_line(x: Option<String>) -> Option<String> {
776 x.and_then(|x| if x.contains('\n') { None } else { Some(x) })
779 fn nop_block_collapse(block_str: Option<String>, budget: usize) -> Option<String> {
780 debug!("nop_block_collapse {:?} {}", block_str, budget);
781 block_str.map(|block_str| {
782 if block_str.starts_with('{') && budget >= 2 &&
783 (block_str[1..].find(|c: char| !c.is_whitespace()).unwrap() == block_str.len() - 2)
792 fn rewrite_empty_block(
793 context: &RewriteContext,
796 ) -> Option<String> {
797 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) &&
800 return Some("{}".to_owned());
803 // If a block contains only a single-line comment, then leave it on one line.
804 let user_str = context.snippet(block.span);
805 let user_str = user_str.trim();
806 if user_str.starts_with('{') && user_str.ends_with('}') {
807 let comment_str = user_str[1..user_str.len() - 1].trim();
808 if block.stmts.is_empty() && !comment_str.contains('\n') &&
809 !comment_str.starts_with("//") && comment_str.len() + 4 <= shape.width
811 return Some(format!("{{ {} }}", comment_str));
818 fn block_prefix(context: &RewriteContext, block: &ast::Block, shape: Shape) -> Option<String> {
819 Some(match block.rules {
820 ast::BlockCheckMode::Unsafe(..) => {
821 let snippet = context.snippet(block.span);
822 let open_pos = try_opt!(snippet.find_uncommented("{"));
823 // Extract comment between unsafe and block start.
824 let trimmed = &snippet[6..open_pos].trim();
826 if !trimmed.is_empty() {
827 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
828 let budget = try_opt!(shape.width.checked_sub(9));
831 try_opt!(rewrite_comment(
834 Shape::legacy(budget, shape.indent + 7),
842 ast::BlockCheckMode::Default => String::new(),
846 fn rewrite_single_line_block(
847 context: &RewriteContext,
851 ) -> Option<String> {
852 if is_simple_block(block, context.codemap) {
853 let expr_shape = Shape::legacy(shape.width - prefix.len(), shape.indent);
854 let expr_str = try_opt!(block.stmts[0].rewrite(context, expr_shape));
855 let result = format!("{}{{ {} }}", prefix, expr_str);
856 if result.len() <= shape.width && !result.contains('\n') {
863 fn rewrite_block_with_visitor(
864 context: &RewriteContext,
868 ) -> Option<String> {
869 if let rw @ Some(_) = rewrite_empty_block(context, block, shape) {
873 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
874 visitor.block_indent = shape.indent;
875 visitor.is_if_else_block = context.is_if_else_block;
877 ast::BlockCheckMode::Unsafe(..) => {
878 let snippet = context.snippet(block.span);
879 let open_pos = try_opt!(snippet.find_uncommented("{"));
880 visitor.last_pos = block.span.lo + BytePos(open_pos as u32)
882 ast::BlockCheckMode::Default => visitor.last_pos = block.span.lo,
885 visitor.visit_block(block);
886 if visitor.failed && shape.indent.alignment != 0 {
889 Shape::indented(shape.indent.block_only(), context.config),
892 Some(format!("{}{}", prefix, visitor.buffer))
896 impl Rewrite for ast::Block {
897 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
898 // shape.width is used only for the single line case: either the empty block `{}`,
899 // or an unsafe expression `unsafe { e }`.
900 if let rw @ Some(_) = rewrite_empty_block(context, self, shape) {
904 let prefix = try_opt!(block_prefix(context, self, shape));
905 if let rw @ Some(_) = rewrite_single_line_block(context, &prefix, self, shape) {
909 rewrite_block_with_visitor(context, &prefix, self, shape)
913 impl Rewrite for ast::Stmt {
914 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
915 let result = match self.node {
916 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
917 ast::StmtKind::Expr(ref ex) |
918 ast::StmtKind::Semi(ref ex) => {
919 let suffix = if semicolon_for_stmt(self) { ";" } else { "" };
924 ast::StmtKind::Expr(_) => ExprType::SubExpression,
925 ast::StmtKind::Semi(_) => ExprType::Statement,
929 try_opt!(shape.sub_width(suffix.len())),
930 ).map(|s| s + suffix)
932 ast::StmtKind::Mac(..) |
933 ast::StmtKind::Item(..) => None,
935 result.and_then(|res| {
936 recover_comment_removed(res, self.span, context, shape)
941 // Rewrite condition if the given expression has one.
942 fn rewrite_cond(context: &RewriteContext, expr: &ast::Expr, shape: Shape) -> Option<String> {
944 ast::ExprKind::Match(ref cond, _) => {
946 let cond_shape = match context.config.control_style() {
947 Style::Legacy => try_opt!(shape.shrink_left(6).and_then(|s| s.sub_width(2))),
948 Style::Rfc => try_opt!(shape.offset_left(8)),
950 cond.rewrite(context, cond_shape)
952 ast::ExprKind::Block(ref block) if block.stmts.len() == 1 => {
953 stmt_expr(&block.stmts[0]).and_then(|e| rewrite_cond(context, e, shape))
956 to_control_flow(expr, ExprType::SubExpression).and_then(|control_flow| {
958 String::from("\n") + &shape.indent.block_only().to_string(context.config);
960 .rewrite_cond(context, shape, &alt_block_sep)
961 .and_then(|rw| Some(rw.0))
967 // Abstraction over control flow expressions
969 struct ControlFlow<'a> {
970 cond: Option<&'a ast::Expr>,
971 block: &'a ast::Block,
972 else_block: Option<&'a ast::Expr>,
973 label: Option<ast::SpannedIdent>,
974 pat: Option<&'a ast::Pat>,
978 allow_single_line: bool,
979 // True if this is an `if` expression in an `else if` :-( hacky
984 fn to_control_flow<'a>(expr: &'a ast::Expr, expr_type: ExprType) -> Option<ControlFlow<'a>> {
986 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => {
987 Some(ControlFlow::new_if(
991 else_block.as_ref().map(|e| &**e),
992 expr_type == ExprType::SubExpression,
997 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
998 Some(ControlFlow::new_if(
1002 else_block.as_ref().map(|e| &**e),
1003 expr_type == ExprType::SubExpression,
1008 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
1009 Some(ControlFlow::new_for(pat, cond, block, label, expr.span))
1011 ast::ExprKind::Loop(ref block, label) => Some(
1012 ControlFlow::new_loop(block, label, expr.span),
1014 ast::ExprKind::While(ref cond, ref block, label) => Some(
1015 ControlFlow::new_while(None, cond, block, label, expr.span),
1017 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => {
1018 Some(ControlFlow::new_while(
1030 impl<'a> ControlFlow<'a> {
1032 cond: &'a ast::Expr,
1033 pat: Option<&'a ast::Pat>,
1034 block: &'a ast::Block,
1035 else_block: Option<&'a ast::Expr>,
1036 allow_single_line: bool,
1039 ) -> ControlFlow<'a> {
1043 else_block: else_block,
1047 matcher: match pat {
1052 allow_single_line: allow_single_line,
1053 nested_if: nested_if,
1059 block: &'a ast::Block,
1060 label: Option<ast::SpannedIdent>,
1062 ) -> ControlFlow<'a> {
1072 allow_single_line: false,
1079 pat: Option<&'a ast::Pat>,
1080 cond: &'a ast::Expr,
1081 block: &'a ast::Block,
1082 label: Option<ast::SpannedIdent>,
1084 ) -> ControlFlow<'a> {
1092 matcher: match pat {
1097 allow_single_line: false,
1105 cond: &'a ast::Expr,
1106 block: &'a ast::Block,
1107 label: Option<ast::SpannedIdent>,
1109 ) -> ControlFlow<'a> {
1119 allow_single_line: false,
1125 fn rewrite_single_line(
1128 context: &RewriteContext,
1130 ) -> Option<String> {
1131 assert!(self.allow_single_line);
1132 let else_block = try_opt!(self.else_block);
1133 let fixed_cost = self.keyword.len() + " { } else { }".len();
1135 if let ast::ExprKind::Block(ref else_node) = else_block.node {
1136 if !is_simple_block(self.block, context.codemap) ||
1137 !is_simple_block(else_node, context.codemap) ||
1138 pat_expr_str.contains('\n')
1143 let new_width = try_opt!(width.checked_sub(pat_expr_str.len() + fixed_cost));
1144 let expr = &self.block.stmts[0];
1145 let if_str = try_opt!(expr.rewrite(
1147 Shape::legacy(new_width, Indent::empty()),
1150 let new_width = try_opt!(new_width.checked_sub(if_str.len()));
1151 let else_expr = &else_node.stmts[0];
1153 try_opt!(else_expr.rewrite(context, Shape::legacy(new_width, Indent::empty())));
1155 if if_str.contains('\n') || else_str.contains('\n') {
1159 let result = format!(
1160 "{} {} {{ {} }} else {{ {} }}",
1167 if result.len() <= width {
1168 return Some(result);
1176 impl<'a> ControlFlow<'a> {
1179 context: &RewriteContext,
1181 alt_block_sep: &str,
1182 ) -> Option<(String, usize)> {
1183 let constr_shape = if self.nested_if {
1184 // We are part of an if-elseif-else chain. Our constraints are tightened.
1185 // 7 = "} else " .len()
1186 try_opt!(shape.shrink_left(7))
1191 let label_string = rewrite_label(self.label);
1192 // 1 = space after keyword.
1193 let offset = self.keyword.len() + label_string.len() + 1;
1195 let pat_expr_string = match self.cond {
1197 let mut cond_shape = match context.config.control_style() {
1198 Style::Legacy => try_opt!(constr_shape.shrink_left(offset)),
1199 Style::Rfc => try_opt!(constr_shape.offset_left(offset)),
1201 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
1203 cond_shape = try_opt!(cond_shape.sub_width(2));
1206 try_opt!(rewrite_pat_expr(
1216 None => String::new(),
1219 let force_newline_brace = context.config.control_style() == Style::Rfc &&
1220 pat_expr_string.contains('\n') &&
1221 !last_line_extendable(&pat_expr_string);
1223 // Try to format if-else on single line.
1224 if self.allow_single_line && context.config.single_line_if_else_max_width() > 0 {
1225 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
1227 if let Some(cond_str) = trial {
1228 if cond_str.len() <= context.config.single_line_if_else_max_width() {
1229 return Some((cond_str, 0));
1234 let cond_span = if let Some(cond) = self.cond {
1237 mk_sp(self.block.span.lo, self.block.span.lo)
1240 // for event in event
1241 let between_kwd_cond = mk_sp(
1242 context.codemap.span_after(self.span, self.keyword.trim()),
1245 |p| if self.matcher.is_empty() {
1248 context.codemap.span_before(self.span, self.matcher.trim())
1253 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
1255 let after_cond_comment =
1256 extract_comment(mk_sp(cond_span.hi, self.block.span.lo), context, shape);
1258 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
1260 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine ||
1268 let used_width = if pat_expr_string.contains('\n') {
1269 last_line_width(&pat_expr_string)
1271 // 2 = spaces after keyword and condition.
1272 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
1280 between_kwd_cond_comment.as_ref().map_or(
1281 if pat_expr_string.is_empty() ||
1282 pat_expr_string.starts_with('\n')
1291 after_cond_comment.as_ref().map_or(block_sep, |s| &**s)
1298 impl<'a> Rewrite for ControlFlow<'a> {
1299 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1300 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
1303 String::from("\n") + &shape.indent.block_only().to_string(context.config);
1304 let (cond_str, used_width) = try_opt!(self.rewrite_cond(context, shape, &alt_block_sep));
1305 // If `used_width` is 0, it indicates that whole control flow is written in a single line.
1306 if used_width == 0 {
1307 return Some(cond_str);
1310 let block_width = shape.width.checked_sub(used_width).unwrap_or(0);
1311 // This is used only for the empty block case: `{}`. So, we use 1 if we know
1312 // we should avoid the single line case.
1313 let block_width = if self.else_block.is_some() || self.nested_if {
1318 let block_shape = Shape {
1322 let mut block_context = context.clone();
1323 block_context.is_if_else_block = self.else_block.is_some();
1324 let block_str = try_opt!(rewrite_block_with_visitor(
1331 let mut result = format!("{}{}", cond_str, block_str);
1333 if let Some(else_block) = self.else_block {
1334 let shape = Shape::indented(shape.indent, context.config);
1335 let mut last_in_chain = false;
1336 let rewrite = match else_block.node {
1337 // If the else expression is another if-else expression, prevent it
1338 // from being formatted on a single line.
1339 // Note how we're passing the original shape, as the
1340 // cost of "else" should not cascade.
1341 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1342 ControlFlow::new_if(
1346 next_else_block.as_ref().map(|e| &**e),
1349 mk_sp(else_block.span.lo, self.span.hi),
1350 ).rewrite(context, shape)
1352 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1353 ControlFlow::new_if(
1357 next_else_block.as_ref().map(|e| &**e),
1360 mk_sp(else_block.span.lo, self.span.hi),
1361 ).rewrite(context, shape)
1364 last_in_chain = true;
1365 // When rewriting a block, the width is only used for single line
1366 // blocks, passing 1 lets us avoid that.
1367 let else_shape = Shape {
1368 width: min(1, shape.width),
1371 format_expr(else_block, ExprType::Statement, context, else_shape)
1375 let between_kwd_else_block = mk_sp(
1379 .span_before(mk_sp(self.block.span.hi, else_block.span.lo), "else"),
1381 let between_kwd_else_block_comment =
1382 extract_comment(between_kwd_else_block, context, shape);
1384 let after_else = mk_sp(
1387 .span_after(mk_sp(self.block.span.hi, else_block.span.lo), "else"),
1390 let after_else_comment = extract_comment(after_else, context, shape);
1392 let between_sep = match context.config.control_brace_style() {
1393 ControlBraceStyle::AlwaysNextLine |
1394 ControlBraceStyle::ClosingNextLine => &*alt_block_sep,
1395 ControlBraceStyle::AlwaysSameLine => " ",
1397 let after_sep = match context.config.control_brace_style() {
1398 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1405 between_kwd_else_block_comment
1407 .map_or(between_sep, |s| &**s),
1408 after_else_comment.as_ref().map_or(after_sep, |s| &**s)
1411 result.push_str(&try_opt!(rewrite));
1418 fn rewrite_label(label: Option<ast::SpannedIdent>) -> String {
1420 Some(ident) => format!("{}: ", ident.node),
1421 None => "".to_owned(),
1425 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1426 let comment_str = context.snippet(span);
1427 if contains_comment(&comment_str) {
1428 let comment = try_opt!(rewrite_comment(
1435 "\n{indent}{}\n{indent}",
1437 indent = shape.indent.to_string(context.config)
1444 fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool {
1445 let snippet = codemap.span_to_snippet(block.span).unwrap();
1446 contains_comment(&snippet)
1449 // Checks that a block contains no statements, an expression and no comments.
1450 // FIXME: incorrectly returns false when comment is contained completely within
1452 pub fn is_simple_block(block: &ast::Block, codemap: &CodeMap) -> bool {
1453 (block.stmts.len() == 1 && stmt_is_expr(&block.stmts[0]) &&
1454 !block_contains_comment(block, codemap))
1457 /// Checks whether a block contains at most one statement or expression, and no comments.
1458 pub fn is_simple_block_stmt(block: &ast::Block, codemap: &CodeMap) -> bool {
1459 block.stmts.len() <= 1 && !block_contains_comment(block, codemap)
1462 /// Checks whether a block contains no statements, expressions, or comments.
1463 pub fn is_empty_block(block: &ast::Block, codemap: &CodeMap) -> bool {
1464 block.stmts.is_empty() && !block_contains_comment(block, codemap)
1467 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1469 ast::StmtKind::Expr(..) => true,
1474 fn is_unsafe_block(block: &ast::Block) -> bool {
1475 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1482 // inter-match-arm-comment-rules:
1483 // - all comments following a match arm before the start of the next arm
1484 // are about the second arm
1485 fn rewrite_match_arm_comment(
1486 context: &RewriteContext,
1489 arm_indent_str: &str,
1490 ) -> Option<String> {
1491 // The leading "," is not part of the arm-comment
1492 let missed_str = match missed_str.find_uncommented(",") {
1493 Some(n) => &missed_str[n + 1..],
1494 None => &missed_str[..],
1497 let mut result = String::new();
1498 // any text not preceeded by a newline is pushed unmodified to the block
1499 let first_brk = missed_str.find(|c: char| c == '\n').unwrap_or(0);
1500 result.push_str(&missed_str[..first_brk]);
1501 let missed_str = &missed_str[first_brk..]; // If missed_str had one newline, it starts with it
1503 let first = missed_str
1504 .find(|c: char| !c.is_whitespace())
1505 .unwrap_or(missed_str.len());
1506 if missed_str[..first].chars().filter(|c| c == &'\n').count() >= 2 {
1507 // Excessive vertical whitespace before comment should be preserved
1508 // FIXME handle vertical whitespace better
1511 let missed_str = missed_str[first..].trim();
1512 if !missed_str.is_empty() {
1513 let comment = try_opt!(rewrite_comment(&missed_str, false, shape, context.config));
1515 result.push_str(arm_indent_str);
1516 result.push_str(&comment);
1523 context: &RewriteContext,
1528 ) -> Option<String> {
1529 if arms.is_empty() {
1534 let cond_shape = match context.config.control_style() {
1535 Style::Legacy => try_opt!(shape.shrink_left(6).and_then(|s| s.sub_width(2))),
1536 Style::Rfc => try_opt!(shape.offset_left(8)),
1538 let cond_str = try_opt!(cond.rewrite(context, cond_shape));
1539 let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config);
1540 let block_sep = match context.config.control_brace_style() {
1541 ControlBraceStyle::AlwaysNextLine => alt_block_sep.as_str(),
1544 let mut result = format!("match {}{}{{", cond_str, block_sep);
1546 let arm_shape = if context.config.indent_match_arms() {
1547 shape.block_indent(context.config.tab_spaces())
1549 shape.block_indent(0)
1552 let arm_indent_str = arm_shape.indent.to_string(context.config);
1554 let open_brace_pos = context
1556 .span_after(mk_sp(cond.span.hi, arm_start_pos(&arms[0])), "{");
1558 let arm_num = arms.len();
1559 for (i, arm) in arms.iter().enumerate() {
1560 // Make sure we get the stuff between arms.
1561 let missed_str = if i == 0 {
1562 context.snippet(mk_sp(open_brace_pos, arm_start_pos(arm)))
1564 context.snippet(mk_sp(arm_end_pos(&arms[i - 1]), arm_start_pos(arm)))
1566 let comment = try_opt!(rewrite_match_arm_comment(
1572 result.push_str(&comment);
1574 result.push_str(&arm_indent_str);
1576 let arm_str = arm.rewrite(&context, arm_shape.with_max_width(context.config));
1577 if let Some(ref arm_str) = arm_str {
1578 // Trim the trailing comma if necessary.
1579 if i == arm_num - 1 && context.config.trailing_comma() == SeparatorTactic::Never &&
1580 arm_str.ends_with(',')
1582 result.push_str(&arm_str[0..arm_str.len() - 1])
1584 result.push_str(arm_str)
1587 // We couldn't format the arm, just reproduce the source.
1588 let snippet = context.snippet(mk_sp(arm_start_pos(arm), arm_end_pos(arm)));
1589 result.push_str(&snippet);
1590 if context.config.trailing_comma() != SeparatorTactic::Never {
1591 result.push_str(arm_comma(context.config, &arm.body))
1595 // BytePos(1) = closing match brace.
1596 let last_span = mk_sp(arm_end_pos(&arms[arms.len() - 1]), span.hi - BytePos(1));
1597 let last_comment = context.snippet(last_span);
1598 let comment = try_opt!(rewrite_match_arm_comment(
1604 result.push_str(&comment);
1606 result.push_str(&shape.indent.to_string(context.config));
1611 fn arm_start_pos(arm: &ast::Arm) -> BytePos {
1617 if !attrs.is_empty() {
1618 return attrs[0].span.lo;
1624 fn arm_end_pos(arm: &ast::Arm) -> BytePos {
1628 fn arm_comma(config: &Config, body: &ast::Expr) -> &'static str {
1629 if config.match_block_trailing_comma() {
1631 } else if let ast::ExprKind::Block(ref block) = body.node {
1632 if let ast::BlockCheckMode::Default = block.rules {
1643 impl Rewrite for ast::Arm {
1644 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1645 debug!("Arm::rewrite {:?} {:?}", self, shape);
1653 let attr_str = if !attrs.is_empty() {
1654 if contains_skip(attrs) {
1659 try_opt!(attrs.rewrite(context, shape)),
1660 shape.indent.to_string(context.config)
1668 let pat_shape = try_opt!(shape.sub_width(5));
1670 let pat_strs = try_opt!(
1672 .map(|p| p.rewrite(context, pat_shape))
1673 .collect::<Option<Vec<_>>>()
1676 let all_simple = pat_strs.iter().all(|p| pat_is_simple(p));
1677 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1678 let fmt = ListFormatting {
1679 tactic: if all_simple {
1680 DefinitiveListTactic::Mixed
1682 DefinitiveListTactic::Vertical
1685 trailing_separator: SeparatorTactic::Never,
1687 ends_with_newline: false,
1688 config: context.config,
1690 let pats_str = try_opt!(write_list(items, &fmt));
1692 let guard_shape = if pats_str.contains('\n') {
1693 shape.with_max_width(context.config)
1698 let guard_str = try_opt!(rewrite_guard(
1702 trimmed_last_line_width(&pats_str),
1705 let pats_str = format!("{}{}", pats_str, guard_str);
1707 let (mut extend, body) = match body.node {
1708 ast::ExprKind::Block(ref block)
1709 if !is_unsafe_block(block) && is_simple_block(block, context.codemap) &&
1710 context.config.wrap_match_arms() => {
1711 if let ast::StmtKind::Expr(ref expr) = block.stmts[0].node {
1717 ast::ExprKind::Call(_, ref args) => (args.len() == 1, &**body),
1718 ast::ExprKind::Closure(..) |
1719 ast::ExprKind::Struct(..) |
1720 ast::ExprKind::Tup(..) => (true, &**body),
1721 _ => (false, &**body),
1723 extend &= context.use_block_indent();
1725 let comma = arm_comma(&context.config, body);
1727 String::from("\n") + &shape.indent.block_only().to_string(context.config);
1729 let pat_width = extra_offset(&pats_str, shape);
1730 // Let's try and get the arm body on the same line as the condition.
1732 if shape.width > pat_width + comma.len() + 4 {
1733 let arm_shape = shape
1734 .offset_left(pat_width + 4)
1736 .sub_width(comma.len())
1738 let rewrite = nop_block_collapse(
1739 format_expr(body, ExprType::Statement, context, arm_shape),
1742 let is_block = if let ast::ExprKind::Block(..) = body.node {
1750 if (!body_str.contains('\n') && body_str.len() <= arm_shape.width) ||
1751 !context.config.wrap_match_arms() ||
1752 (extend && first_line_width(body_str) <= arm_shape.width) ||
1754 let block_sep = match context.config.control_brace_style() {
1755 ControlBraceStyle::AlwaysNextLine if is_block => alt_block_sep.as_str(),
1759 return Some(format!(
1761 attr_str.trim_left(),
1772 // FIXME: we're doing a second rewrite of the expr; This may not be
1774 let body_shape = try_opt!(shape.block_left(context.config.tab_spaces()));
1775 let next_line_body = try_opt!(nop_block_collapse(
1776 format_expr(body, ExprType::Statement, context, body_shape),
1779 let indent_str = shape
1781 .block_indent(context.config)
1782 .to_string(context.config);
1783 let (body_prefix, body_suffix) = if context.config.wrap_match_arms() {
1784 if context.config.match_block_trailing_comma() {
1794 let block_sep = match context.config.control_brace_style() {
1795 ControlBraceStyle::AlwaysNextLine => alt_block_sep + body_prefix + "\n",
1796 _ if body_prefix.is_empty() => "\n".to_owned(),
1797 _ => " ".to_owned() + body_prefix + "\n",
1800 if context.config.wrap_match_arms() {
1802 "{}{} =>{}{}{}\n{}{}",
1803 attr_str.trim_left(),
1808 shape.indent.to_string(context.config),
1814 attr_str.trim_left(),
1825 // A pattern is simple if it is very short or it is short-ish and just a path.
1826 // E.g. `Foo::Bar` is simple, but `Foo(..)` is not.
1827 fn pat_is_simple(pat_str: &str) -> bool {
1828 pat_str.len() <= 16 ||
1829 (pat_str.len() <= 24 && pat_str.chars().all(|c| c.is_alphabetic() || c == ':'))
1832 // The `if ...` guard on a match arm.
1834 context: &RewriteContext,
1835 guard: &Option<ptr::P<ast::Expr>>,
1837 // The amount of space used up on this line for the pattern in
1838 // the arm (excludes offset).
1839 pattern_width: usize,
1840 ) -> Option<String> {
1841 if let Some(ref guard) = *guard {
1842 // First try to fit the guard string on the same line as the pattern.
1843 // 4 = ` if `, 5 = ` => {`
1844 if let Some(cond_shape) = shape
1845 .shrink_left(pattern_width + 4)
1846 .and_then(|s| s.sub_width(5))
1848 if let Some(cond_str) = guard
1849 .rewrite(context, cond_shape)
1850 .and_then(|s| s.rewrite(context, cond_shape))
1852 if !cond_str.contains('\n') {
1853 return Some(format!(" if {}", cond_str));
1858 // Not enough space to put the guard after the pattern, try a newline.
1860 if let Some(cond_shape) = Shape::indented(
1861 shape.indent.block_indent(context.config) + 3,
1865 if let Some(cond_str) = guard.rewrite(context, cond_shape) {
1866 return Some(format!(
1870 .block_indent(context.config)
1871 .to_string(context.config),
1883 fn rewrite_pat_expr(
1884 context: &RewriteContext,
1885 pat: Option<&ast::Pat>,
1888 // Connecting piece between pattern and expression,
1889 // *without* trailing space.
1893 ) -> Option<String> {
1894 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, pat, expr);
1895 let mut pat_string = String::new();
1896 let mut result = match pat {
1898 let matcher = if matcher.is_empty() {
1901 format!("{} ", matcher)
1904 try_opt!(try_opt!(shape.offset_left(matcher.len())).sub_width(connector.len()));
1905 pat_string = try_opt!(pat.rewrite(context, pat_shape));
1906 format!("{}{}{}", matcher, pat_string, connector)
1908 None => String::new(),
1911 // Consider only the last line of the pat string.
1912 let extra_offset = extra_offset(&result, shape);
1914 // The expression may (partially) fit on the current line.
1915 if shape.width > extra_offset + 1 {
1916 let spacer = if pat.is_some() { " " } else { "" };
1918 let expr_shape = try_opt!(shape.offset_left(extra_offset + spacer.len()));
1919 let expr_rewrite = expr.rewrite(context, expr_shape);
1921 if let Some(expr_string) = expr_rewrite {
1922 if pat.is_none() || pat_is_simple(&pat_string) || !expr_string.contains('\n') {
1923 result.push_str(spacer);
1924 result.push_str(&expr_string);
1925 return Some(result);
1930 if pat.is_none() && keyword == "if" {
1934 let nested_indent = shape.indent.block_only().block_indent(context.config);
1936 // The expression won't fit on the current line, jump to next.
1938 result.push_str(&nested_indent.to_string(context.config));
1940 let expr_rewrite = expr.rewrite(&context, Shape::indented(nested_indent, context.config));
1941 result.push_str(&try_opt!(expr_rewrite));
1946 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1947 let string_lit = context.snippet(span);
1949 if !context.config.format_strings() && !context.config.force_format_strings() {
1954 .all(|line| line.ends_with('\\'))
1956 let new_indent = shape.visual_indent(1).indent;
1957 return Some(String::from(
1961 new_indent.to_string(context.config) + line.trim_left()
1963 .collect::<Vec<_>>()
1968 return Some(string_lit);
1972 if !context.config.force_format_strings() &&
1973 !string_requires_rewrite(context, span, &string_lit, shape)
1975 return Some(string_lit);
1978 let fmt = StringFormat {
1985 config: context.config,
1988 // Remove the quote characters.
1989 let str_lit = &string_lit[1..string_lit.len() - 1];
1991 rewrite_string(str_lit, &fmt)
1994 fn string_requires_rewrite(
1995 context: &RewriteContext,
2000 if context.codemap.lookup_char_pos(span.lo).col.0 != shape.indent.width() {
2004 for (i, line) in string.lines().enumerate() {
2006 if line.len() > shape.width {
2010 if line.len() > shape.width + shape.indent.width() {
2019 pub fn rewrite_call_with_binary_search<R>(
2020 context: &RewriteContext,
2022 args: &[&ast::Expr],
2029 let force_trailing_comma = if context.inside_macro {
2030 span_ends_with_comma(context, span)
2034 let closure = |callee_max_width| {
2035 // FIXME using byte lens instead of char lens (and probably all over the
2037 let callee_shape = Shape {
2038 width: callee_max_width,
2041 let callee_str = callee
2042 .rewrite(context, callee_shape)
2043 .ok_or(Ordering::Greater)?;
2051 context.config.fn_call_width(),
2052 force_trailing_comma,
2056 binary_search(1, shape.width, closure)
2059 pub fn rewrite_call(
2060 context: &RewriteContext,
2062 args: &[ptr::P<ast::Expr>],
2065 ) -> Option<String> {
2066 let force_trailing_comma = if context.inside_macro {
2067 span_ends_with_comma(context, span)
2074 &args.iter().map(|x| &**x).collect::<Vec<_>>(),
2077 context.config.fn_call_width(),
2078 force_trailing_comma,
2082 pub fn rewrite_call_inner<'a, T>(
2083 context: &RewriteContext,
2088 args_max_width: usize,
2089 force_trailing_comma: bool,
2090 ) -> Result<String, Ordering>
2092 T: Rewrite + Spanned + ToExpr + 'a,
2094 // 2 = `( `, 1 = `(`
2095 let paren_overhead = if context.config.spaces_within_parens() {
2100 let used_width = extra_offset(&callee_str, shape);
2101 let one_line_width = shape
2103 .checked_sub(used_width + 2 * paren_overhead)
2104 .ok_or(Ordering::Greater)?;
2106 let nested_shape = shape_from_fn_call_style(
2109 used_width + 2 * paren_overhead,
2110 used_width + paren_overhead,
2111 ).ok_or(Ordering::Greater)?;
2113 let span_lo = context.codemap.span_after(span, "(");
2114 let args_span = mk_sp(span_lo, span.hi);
2116 let (extendable, list_str) = rewrite_call_args(
2123 force_trailing_comma,
2124 ).or_else(|| if context.use_block_indent() {
2130 shape.block().indent.block_indent(context.config),
2135 force_trailing_comma,
2140 .ok_or(Ordering::Less)?;
2142 if !context.use_block_indent() && need_block_indent(&list_str, nested_shape) && !extendable {
2143 let mut new_context = context.clone();
2144 new_context.use_block = true;
2145 return rewrite_call_inner(
2152 force_trailing_comma,
2156 let args_shape = shape
2157 .sub_width(last_line_width(&callee_str))
2158 .ok_or(Ordering::Less)?;
2162 wrap_args_with_parens(context, &list_str, extendable, args_shape, nested_shape)
2166 fn need_block_indent(s: &str, shape: Shape) -> bool {
2167 s.lines().skip(1).any(|s| {
2168 s.find(|c| !char::is_whitespace(c))
2169 .map_or(false, |w| w + 1 < shape.indent.width())
2173 fn rewrite_call_args<'a, T>(
2174 context: &RewriteContext,
2178 one_line_width: usize,
2179 args_max_width: usize,
2180 force_trailing_comma: bool,
2181 ) -> Option<(bool, String)>
2183 T: Rewrite + Spanned + ToExpr + 'a,
2185 let items = itemize_list(
2189 |item| item.span().lo,
2190 |item| item.span().hi,
2191 |item| item.rewrite(context, shape),
2195 let mut item_vec: Vec<_> = items.collect();
2197 // Try letting the last argument overflow to the next line with block
2198 // indentation. If its first line fits on one line with the other arguments,
2199 // we format the function arguments horizontally.
2200 let tactic = try_overflow_last_arg(
2209 let fmt = ListFormatting {
2212 trailing_separator: if force_trailing_comma {
2213 SeparatorTactic::Always
2214 } else if context.inside_macro || !context.use_block_indent() {
2215 SeparatorTactic::Never
2217 context.config.trailing_comma()
2220 ends_with_newline: false,
2221 config: context.config,
2224 write_list(&item_vec, &fmt).map(|args_str| {
2225 (tactic != DefinitiveListTactic::Vertical, args_str)
2229 fn try_overflow_last_arg<'a, T>(
2230 context: &RewriteContext,
2231 item_vec: &mut Vec<ListItem>,
2234 one_line_width: usize,
2235 args_max_width: usize,
2236 ) -> DefinitiveListTactic
2238 T: Rewrite + Spanned + ToExpr + 'a,
2240 let overflow_last = can_be_overflowed(&context, args);
2242 // Replace the last item with its first line to see if it fits with
2244 let (orig_last, placeholder) = if overflow_last {
2245 let mut context = context.clone();
2246 if let Some(expr) = args[args.len() - 1].to_expr() {
2248 ast::ExprKind::MethodCall(..) => context.force_one_line_chain = true,
2252 last_arg_shape(&context, &item_vec, shape, args_max_width)
2253 .map_or((None, None), |arg_shape| {
2254 rewrite_last_arg_with_overflow(
2257 &mut item_vec[args.len() - 1],
2265 let tactic = definitive_tactic(
2267 ListTactic::LimitedHorizontalVertical(args_max_width),
2271 // Replace the stub with the full overflowing last argument if the rewrite
2272 // succeeded and its first line fits with the other arguments.
2273 match (overflow_last, tactic, placeholder) {
2274 (true, DefinitiveListTactic::Horizontal, placeholder @ Some(..)) => {
2275 item_vec[args.len() - 1].item = placeholder;
2278 item_vec[args.len() - 1].item = orig_last;
2287 context: &RewriteContext,
2288 items: &Vec<ListItem>,
2290 args_max_width: usize,
2291 ) -> Option<Shape> {
2292 let overhead = items.iter().rev().skip(1).fold(0, |acc, i| {
2293 acc + i.item.as_ref().map_or(0, |s| first_line_width(&s))
2295 let max_width = min(args_max_width, shape.width);
2296 let arg_indent = if context.use_block_indent() {
2297 shape.block().indent.block_unindent(context.config)
2299 shape.block().indent
2302 width: try_opt!(max_width.checked_sub(overhead)),
2308 // Rewriting closure which is placed at the end of the function call's arg.
2309 // Returns `None` if the reformatted closure 'looks bad'.
2310 fn rewrite_last_closure(
2311 context: &RewriteContext,
2314 ) -> Option<String> {
2315 if let ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) = expr.node {
2316 let body = match body.node {
2317 ast::ExprKind::Block(ref block) if block.stmts.len() == 1 => {
2318 stmt_expr(&block.stmts[0]).unwrap_or(body)
2322 let (prefix, extra_offset) = try_opt!(rewrite_closure_fn_decl(
2330 // If the closure goes multi line before its body, do not overflow the closure.
2331 if prefix.contains('\n') {
2334 let body_shape = try_opt!(shape.offset_left(extra_offset));
2335 // When overflowing the closure which consists of a single control flow expression,
2336 // force to use block if its condition uses multi line.
2337 if rewrite_cond(context, body, body_shape)
2338 .map(|cond| cond.contains('\n'))
2341 return rewrite_closure_with_block(context, body_shape, &prefix, body);
2344 // Seems fine, just format the closure in usual manner.
2345 return expr.rewrite(context, shape);
2350 fn rewrite_last_arg_with_overflow<'a, T>(
2351 context: &RewriteContext,
2353 last_item: &mut ListItem,
2355 ) -> (Option<String>, Option<String>)
2357 T: Rewrite + Spanned + ToExpr + 'a,
2359 let last_arg = args[args.len() - 1];
2360 let rewrite = if let Some(expr) = last_arg.to_expr() {
2362 // When overflowing the closure which consists of a single control flow expression,
2363 // force to use block if its condition uses multi line.
2364 ast::ExprKind::Closure(..) => {
2365 // If the argument consists of multiple closures, we do not overflow
2366 // the last closure.
2367 if args.len() > 1 &&
2371 .filter_map(|arg| arg.to_expr())
2372 .any(|expr| match expr.node {
2373 ast::ExprKind::Closure(..) => true,
2378 rewrite_last_closure(context, expr, shape)
2381 _ => expr.rewrite(context, shape),
2384 last_arg.rewrite(context, shape)
2386 let orig_last = last_item.item.clone();
2388 if let Some(rewrite) = rewrite {
2389 let rewrite_first_line = Some(rewrite[..first_line_width(&rewrite)].to_owned());
2390 last_item.item = rewrite_first_line;
2391 (orig_last, Some(rewrite))
2397 fn can_be_overflowed<'a, T>(context: &RewriteContext, args: &[&T]) -> bool
2399 T: Rewrite + Spanned + ToExpr + 'a,
2402 .map_or(false, |x| x.can_be_overflowed(context, args.len()))
2405 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
2407 ast::ExprKind::Match(..) => {
2408 (context.use_block_indent() && args_len == 1) ||
2409 (context.config.fn_call_style() == IndentStyle::Visual && args_len > 1)
2411 ast::ExprKind::If(..) |
2412 ast::ExprKind::IfLet(..) |
2413 ast::ExprKind::ForLoop(..) |
2414 ast::ExprKind::Loop(..) |
2415 ast::ExprKind::While(..) |
2416 ast::ExprKind::WhileLet(..) => {
2417 context.config.combine_control_expr() && context.use_block_indent() && args_len == 1
2419 ast::ExprKind::Block(..) |
2420 ast::ExprKind::Closure(..) => {
2421 context.use_block_indent() ||
2422 context.config.fn_call_style() == IndentStyle::Visual && args_len > 1
2424 ast::ExprKind::Array(..) |
2425 ast::ExprKind::Call(..) |
2426 ast::ExprKind::Mac(..) |
2427 ast::ExprKind::MethodCall(..) |
2428 ast::ExprKind::Struct(..) |
2429 ast::ExprKind::Tup(..) => context.use_block_indent() && args_len == 1,
2430 ast::ExprKind::AddrOf(_, ref expr) |
2431 ast::ExprKind::Box(ref expr) |
2432 ast::ExprKind::Try(ref expr) |
2433 ast::ExprKind::Unary(_, ref expr) |
2434 ast::ExprKind::Cast(ref expr, _) => can_be_overflowed_expr(context, expr, args_len),
2439 fn paren_overhead(context: &RewriteContext) -> usize {
2440 if context.config.spaces_within_parens() {
2447 pub fn wrap_args_with_parens(
2448 context: &RewriteContext,
2450 is_extendable: bool,
2452 nested_shape: Shape,
2454 if !context.use_block_indent() ||
2455 (context.inside_macro && !args_str.contains('\n') &&
2456 args_str.len() + paren_overhead(context) <= shape.width) || is_extendable
2458 if context.config.spaces_within_parens() && args_str.len() > 0 {
2459 format!("( {} )", args_str)
2461 format!("({})", args_str)
2466 nested_shape.indent.to_string(context.config),
2468 shape.block().indent.to_string(context.config)
2473 fn span_ends_with_comma(context: &RewriteContext, span: Span) -> bool {
2474 let snippet = context.snippet(span);
2476 .trim_right_matches(|c: char| c == ')' || c.is_whitespace())
2480 fn rewrite_paren(context: &RewriteContext, subexpr: &ast::Expr, shape: Shape) -> Option<String> {
2481 debug!("rewrite_paren, shape: {:?}", shape);
2482 let paren_overhead = paren_overhead(context);
2483 let sub_shape = try_opt!(shape.sub_width(paren_overhead / 2)).visual_indent(paren_overhead / 2);
2485 let paren_wrapper = |s: &str| if context.config.spaces_within_parens() && s.len() > 0 {
2486 format!("( {} )", s)
2491 let subexpr_str = try_opt!(subexpr.rewrite(context, sub_shape));
2492 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
2494 if subexpr_str.contains('\n') {
2495 Some(paren_wrapper(&subexpr_str))
2497 if subexpr_str.len() + paren_overhead <= shape.width {
2498 Some(paren_wrapper(&subexpr_str))
2500 let sub_shape = try_opt!(shape.offset_left(2));
2501 let subexpr_str = try_opt!(subexpr.rewrite(context, sub_shape));
2502 Some(paren_wrapper(&subexpr_str))
2510 context: &RewriteContext,
2512 ) -> Option<String> {
2513 let expr_str = try_opt!(expr.rewrite(context, shape));
2515 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
2521 let offset = expr_str.len() + lbr.len();
2522 let orig_index_rw = shape
2523 .visual_indent(offset)
2524 .sub_width(offset + rbr.len())
2525 .and_then(|index_shape| index.rewrite(context, index_shape));
2527 // Return if everything fits in a single line.
2528 match orig_index_rw {
2529 Some(ref index_str) if !index_str.contains('\n') => {
2530 return Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr));
2535 // Try putting index on the next line and see if it fits in a single line.
2536 let indent = shape.indent.block_indent(&context.config);
2537 let rhs_overhead = context
2540 .checked_sub(shape.used_width() + shape.width)
2542 let index_shape = try_opt!(Shape::indented(indent, context.config).offset_left(lbr.len()));
2543 let index_shape = try_opt!(index_shape.sub_width(rbr.len() + rhs_overhead));
2544 let new_index_rw = index.rewrite(context, index_shape);
2545 match (orig_index_rw, new_index_rw) {
2546 (_, Some(ref new_index_str)) if !new_index_str.contains('\n') => {
2550 indent.to_string(&context.config),
2556 (None, Some(ref new_index_str)) => {
2560 indent.to_string(&context.config),
2566 (Some(ref index_str), _) => Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr)),
2571 fn struct_lit_can_be_aligned(fields: &[ast::Field], base: &Option<&ast::Expr>) -> bool {
2576 fields.iter().all(|field| !field.is_shorthand)
2579 fn rewrite_struct_lit<'a>(
2580 context: &RewriteContext,
2582 fields: &'a [ast::Field],
2583 base: Option<&'a ast::Expr>,
2586 ) -> Option<String> {
2587 debug!("rewrite_struct_lit: shape {:?}", shape);
2589 enum StructLitField<'a> {
2590 Regular(&'a ast::Field),
2591 Base(&'a ast::Expr),
2595 let path_shape = try_opt!(shape.sub_width(2));
2596 let path_str = try_opt!(rewrite_path(
2604 if fields.len() == 0 && base.is_none() {
2605 return Some(format!("{} {{}}", path_str));
2608 // Foo { a: Foo } - indent is +3, width is -5.
2609 let (h_shape, v_shape) = try_opt!(struct_lit_shape(shape, context, path_str.len() + 3, 2));
2611 let one_line_width = h_shape.map_or(0, |shape| shape.width);
2612 let body_lo = context.codemap.span_after(span, "{");
2613 let fields_str = if struct_lit_can_be_aligned(fields, &base) &&
2614 context.config.struct_field_align_threshold() > 0
2616 try_opt!(rewrite_with_alignment(
2620 mk_sp(body_lo, span.hi),
2624 let field_iter = fields
2626 .map(StructLitField::Regular)
2627 .chain(base.into_iter().map(StructLitField::Base));
2629 let span_lo = |item: &StructLitField| match *item {
2630 StructLitField::Regular(field) => field.span().lo,
2631 StructLitField::Base(expr) => {
2632 let last_field_hi = fields.last().map_or(span.lo, |field| field.span.hi);
2633 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo));
2634 let pos = snippet.find_uncommented("..").unwrap();
2635 last_field_hi + BytePos(pos as u32)
2638 let span_hi = |item: &StructLitField| match *item {
2639 StructLitField::Regular(field) => field.span().hi,
2640 StructLitField::Base(expr) => expr.span.hi,
2642 let rewrite = |item: &StructLitField| match *item {
2643 StructLitField::Regular(field) => {
2644 // The 1 taken from the v_budget is for the comma.
2645 rewrite_field(context, field, try_opt!(v_shape.sub_width(1)), 0)
2647 StructLitField::Base(expr) => {
2649 expr.rewrite(context, try_opt!(v_shape.shrink_left(2)))
2650 .map(|s| format!("..{}", s))
2654 let items = itemize_list(
2664 let item_vec = items.collect::<Vec<_>>();
2666 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
2667 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
2668 let fmt = struct_lit_formatting(nested_shape, tactic, context, base.is_some());
2670 try_opt!(write_list(&item_vec, &fmt))
2673 let fields_str = wrap_struct_field(context, &fields_str, shape, v_shape, one_line_width);
2674 Some(format!("{} {{{}}}", path_str, fields_str))
2676 // FIXME if context.config.struct_lit_style() == Visual, but we run out
2677 // of space, we should fall back to BlockIndent.
2680 pub fn wrap_struct_field(
2681 context: &RewriteContext,
2684 nested_shape: Shape,
2685 one_line_width: usize,
2687 if context.config.struct_lit_style() == IndentStyle::Block &&
2688 (fields_str.contains('\n') ||
2689 context.config.struct_lit_multiline_style() == MultilineStyle::ForceMulti ||
2690 fields_str.len() > one_line_width)
2694 nested_shape.indent.to_string(context.config),
2696 shape.indent.to_string(context.config)
2699 // One liner or visual indent.
2700 format!(" {} ", fields_str)
2704 pub fn struct_lit_field_separator(config: &Config) -> &str {
2706 config.space_before_struct_lit_field_colon(),
2707 config.space_after_struct_lit_field_colon(),
2711 pub fn rewrite_field(
2712 context: &RewriteContext,
2715 prefix_max_width: usize,
2716 ) -> Option<String> {
2717 if contains_skip(&field.attrs) {
2719 context.snippet(field.span()),
2720 context.config.max_width(),
2724 let name = &field.ident.node.to_string();
2725 if field.is_shorthand {
2726 Some(name.to_string())
2728 let mut separator = String::from(struct_lit_field_separator(context.config));
2729 for _ in 0..prefix_max_width.checked_sub(name.len()).unwrap_or(0) {
2730 separator.push(' ');
2732 let overhead = name.len() + separator.len();
2733 let expr_shape = try_opt!(shape.offset_left(overhead));
2734 let expr = field.expr.rewrite(context, expr_shape);
2736 let mut attrs_str = try_opt!(field.attrs.rewrite(context, shape));
2737 if !attrs_str.is_empty() {
2738 attrs_str.push_str(&format!("\n{}", shape.indent.to_string(context.config)));
2742 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
2744 let expr_offset = shape.indent.block_indent(context.config);
2747 .rewrite(context, Shape::indented(expr_offset, context.config));
2753 expr_offset.to_string(&context.config),
2762 fn shape_from_fn_call_style(
2763 context: &RewriteContext,
2767 ) -> Option<Shape> {
2768 if context.use_block_indent() {
2772 .block_indent(context.config.tab_spaces())
2773 .with_max_width(context.config)
2776 shape.visual_indent(offset).sub_width(overhead)
2780 fn rewrite_tuple_in_visual_indent_style<'a, T>(
2781 context: &RewriteContext,
2787 T: Rewrite + Spanned + ToExpr + 'a,
2789 let mut items = items.iter();
2790 // In case of length 1, need a trailing comma
2791 debug!("rewrite_tuple_in_visual_indent_style {:?}", shape);
2792 if items.len() == 1 {
2794 let nested_shape = try_opt!(shape.sub_width(3)).visual_indent(1);
2795 return items.next().unwrap().rewrite(context, nested_shape).map(
2796 |s| if context.config.spaces_within_parens() {
2797 format!("( {}, )", s)
2804 let list_lo = context.codemap.span_after(span, "(");
2805 let nested_shape = try_opt!(shape.sub_width(2)).visual_indent(1);
2806 let items = itemize_list(
2810 |item| item.span().lo,
2811 |item| item.span().hi,
2812 |item| item.rewrite(context, nested_shape),
2814 span.hi - BytePos(1),
2816 let list_str = try_opt!(format_item_list(items, nested_shape, context.config));
2818 if context.config.spaces_within_parens() && list_str.len() > 0 {
2819 Some(format!("( {} )", list_str))
2821 Some(format!("({})", list_str))
2825 pub fn rewrite_tuple<'a, T>(
2826 context: &RewriteContext,
2832 T: Rewrite + Spanned + ToExpr + 'a,
2834 debug!("rewrite_tuple {:?}", shape);
2835 if context.use_block_indent() {
2836 // We use the same rule as funcation call for rewriting tuple.
2837 let force_trailing_comma = if context.inside_macro {
2838 span_ends_with_comma(context, span)
2848 context.config.fn_call_width(),
2849 force_trailing_comma,
2852 rewrite_tuple_in_visual_indent_style(context, items, span, shape)
2856 pub fn rewrite_unary_prefix<R: Rewrite>(
2857 context: &RewriteContext,
2861 ) -> Option<String> {
2863 .rewrite(context, try_opt!(shape.offset_left(prefix.len())))
2864 .map(|r| format!("{}{}", prefix, r))
2867 // FIXME: this is probably not correct for multi-line Rewrites. we should
2868 // subtract suffix.len() from the last line budget, not the first!
2869 pub fn rewrite_unary_suffix<R: Rewrite>(
2870 context: &RewriteContext,
2874 ) -> Option<String> {
2876 .rewrite(context, try_opt!(shape.sub_width(suffix.len())))
2883 fn rewrite_unary_op(
2884 context: &RewriteContext,
2888 ) -> Option<String> {
2889 // For some reason, an UnOp is not spanned like BinOp!
2890 let operator_str = match *op {
2891 ast::UnOp::Deref => "*",
2892 ast::UnOp::Not => "!",
2893 ast::UnOp::Neg => "-",
2895 rewrite_unary_prefix(context, operator_str, expr, shape)
2898 fn rewrite_assignment(
2899 context: &RewriteContext,
2902 op: Option<&ast::BinOp>,
2904 ) -> Option<String> {
2905 let operator_str = match op {
2906 Some(op) => context.snippet(op.span),
2907 None => "=".to_owned(),
2910 // 1 = space between lhs and operator.
2911 let lhs_shape = try_opt!(shape.sub_width(operator_str.len() + 1));
2912 let lhs_str = format!(
2914 try_opt!(lhs.rewrite(context, lhs_shape)),
2918 rewrite_assign_rhs(context, lhs_str, rhs, shape)
2921 // The left hand side must contain everything up to, and including, the
2922 // assignment operator.
2923 pub fn rewrite_assign_rhs<S: Into<String>>(
2924 context: &RewriteContext,
2928 ) -> Option<String> {
2929 let mut result = lhs.into();
2930 let last_line_width = last_line_width(&result) -
2931 if result.contains('\n') {
2932 shape.indent.width()
2936 // 1 = space between operator and rhs.
2937 let orig_shape = try_opt!(shape.offset_left(last_line_width + 1));
2938 let rhs = ex.rewrite(context, orig_shape);
2941 Some(ref new_str) if !new_str.contains('\n') => {
2943 result.push_str(new_str);
2946 // Expression did not fit on the same line as the identifier.
2947 // Try splitting the line and see if that works better.
2948 let new_shape = try_opt!(shape.block_left(context.config.tab_spaces()));
2949 let new_rhs = ex.rewrite(context, new_shape);
2952 match (rhs, new_rhs) {
2953 (Some(ref orig_rhs), Some(ref replacement_rhs))
2954 if prefer_next_line(orig_rhs, replacement_rhs) => {
2955 result.push_str(&format!("\n{}", new_shape.indent.to_string(context.config)));
2956 result.push_str(replacement_rhs);
2958 (None, Some(ref final_rhs)) => {
2959 result.push_str(&format!("\n{}", new_shape.indent.to_string(context.config)));
2960 result.push_str(final_rhs);
2962 (None, None) => return None,
2963 (Some(ref orig_rhs), _) => {
2965 result.push_str(orig_rhs);
2974 fn prefer_next_line(orig_rhs: &str, next_line_rhs: &str) -> bool {
2976 fn count_line_breaks(src: &str) -> usize {
2977 src.chars().filter(|&x| x == '\n').count()
2980 !next_line_rhs.contains('\n') ||
2981 count_line_breaks(orig_rhs) > count_line_breaks(next_line_rhs) + 1
2984 fn rewrite_expr_addrof(
2985 context: &RewriteContext,
2986 mutability: ast::Mutability,
2989 ) -> Option<String> {
2990 let operator_str = match mutability {
2991 ast::Mutability::Immutable => "&",
2992 ast::Mutability::Mutable => "&mut ",
2994 rewrite_unary_prefix(context, operator_str, expr, shape)
2998 fn to_expr(&self) -> Option<&ast::Expr>;
2999 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool;
3002 impl ToExpr for ast::Expr {
3003 fn to_expr(&self) -> Option<&ast::Expr> {
3007 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
3008 can_be_overflowed_expr(context, self, len)
3012 impl ToExpr for ast::Ty {
3013 fn to_expr(&self) -> Option<&ast::Expr> {
3017 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
3018 can_be_overflowed_type(context, self, len)
3022 impl<'a> ToExpr for TuplePatField<'a> {
3023 fn to_expr(&self) -> Option<&ast::Expr> {
3027 fn can_be_overflowed(&self, context: &RewriteContext, len: usize) -> bool {
3028 can_be_overflowed_pat(context, self, len)