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};
14 use std::iter::ExactSizeIterator;
17 use {Indent, Shape, Spanned};
18 use codemap::SpanUtils;
19 use rewrite::{Rewrite, RewriteContext};
20 use lists::{write_list, itemize_list, ListFormatting, SeparatorTactic, ListTactic,
21 DefinitiveListTactic, definitive_tactic, ListItem, format_item_list, struct_lit_shape,
22 struct_lit_tactic, shape_for_tactic, struct_lit_formatting};
23 use string::{StringFormat, rewrite_string};
24 use utils::{extra_offset, last_line_width, wrap_str, binary_search, first_line_width,
25 semicolon_for_stmt, trimmed_last_line_width, left_most_sub_expr, stmt_expr,
27 use visitor::FmtVisitor;
28 use config::{Config, IndentStyle, MultilineStyle, ControlBraceStyle, Style};
29 use comment::{FindUncommented, rewrite_comment, contains_comment, recover_comment_removed};
30 use types::{rewrite_path, PathContext};
31 use items::{span_lo_for_arg, span_hi_for_arg};
32 use chains::rewrite_chain;
33 use macros::{rewrite_macro, MacroPosition};
35 use syntax::{ast, ptr};
36 use syntax::codemap::{CodeMap, Span, BytePos, mk_sp};
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 format_expr(expr: &ast::Expr,
53 context: &RewriteContext,
56 let result = match expr.node {
57 ast::ExprKind::Array(ref expr_vec) => {
58 rewrite_array(expr_vec.iter().map(|e| &**e),
59 mk_sp(context.codemap.span_after(expr.span, "["), expr.span.hi),
63 ast::ExprKind::Lit(ref l) => {
65 ast::LitKind::Str(_, ast::StrStyle::Cooked) => {
66 rewrite_string_lit(context, l.span, shape)
69 wrap_str(context.snippet(expr.span),
70 context.config.max_width(),
75 ast::ExprKind::Call(ref callee, ref args) => {
76 let inner_span = mk_sp(callee.span.hi, expr.span.hi);
77 rewrite_call(context, &**callee, args, inner_span, shape)
79 ast::ExprKind::Paren(ref subexpr) => rewrite_paren(context, subexpr, shape),
80 ast::ExprKind::Binary(ref op, ref lhs, ref rhs) => {
81 // FIXME: format comments between operands and operator
85 &format!(" {} ", context.snippet(op.span)),
90 ast::ExprKind::Unary(ref op, ref subexpr) => rewrite_unary_op(context, op, subexpr, shape),
91 ast::ExprKind::Struct(ref path, ref fields, ref base) => {
92 rewrite_struct_lit(context,
95 base.as_ref().map(|e| &**e),
99 ast::ExprKind::Tup(ref items) => {
100 rewrite_tuple(context, items.iter().map(|x| &**x), expr.span, shape)
102 ast::ExprKind::While(ref cond, ref block, label) => {
103 ControlFlow::new_while(None, cond, block, label, expr.span).rewrite(context, shape)
105 ast::ExprKind::WhileLet(ref pat, ref cond, ref block, label) => {
106 ControlFlow::new_while(Some(pat), cond, block, label, expr.span).rewrite(context, shape)
108 ast::ExprKind::ForLoop(ref pat, ref cond, ref block, label) => {
109 ControlFlow::new_for(pat, cond, block, label, expr.span).rewrite(context, shape)
111 ast::ExprKind::Loop(ref block, label) => {
112 ControlFlow::new_loop(block, label, expr.span).rewrite(context, shape)
114 ast::ExprKind::Block(ref block) => block.rewrite(context, shape),
115 ast::ExprKind::If(ref cond, ref if_block, ref else_block) => {
116 ControlFlow::new_if(cond,
119 else_block.as_ref().map(|e| &**e),
120 expr_type == ExprType::SubExpression,
123 .rewrite(context, shape)
125 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref else_block) => {
126 ControlFlow::new_if(cond,
129 else_block.as_ref().map(|e| &**e),
130 expr_type == ExprType::SubExpression,
133 .rewrite(context, shape)
135 ast::ExprKind::Match(ref cond, ref arms) => {
136 rewrite_match(context, cond, arms, shape, expr.span)
138 ast::ExprKind::Path(ref qself, ref path) => {
139 rewrite_path(context, PathContext::Expr, qself.as_ref(), path, shape)
141 ast::ExprKind::Assign(ref lhs, ref rhs) => {
142 rewrite_assignment(context, lhs, rhs, None, shape)
144 ast::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
145 rewrite_assignment(context, lhs, rhs, Some(op), shape)
147 ast::ExprKind::Continue(ref opt_ident) => {
148 let id_str = match *opt_ident {
149 Some(ident) => format!(" {}", ident.node),
150 None => String::new(),
152 wrap_str(format!("continue{}", id_str),
153 context.config.max_width(),
156 ast::ExprKind::Break(ref opt_ident, ref opt_expr) => {
157 let id_str = match *opt_ident {
158 Some(ident) => format!(" {}", ident.node),
159 None => String::new(),
162 if let Some(ref expr) = *opt_expr {
163 rewrite_unary_prefix(context, &format!("break{} ", id_str), &**expr, shape)
165 wrap_str(format!("break{}", id_str),
166 context.config.max_width(),
170 ast::ExprKind::Closure(capture, ref fn_decl, ref body, _) => {
171 rewrite_closure(capture, fn_decl, body, expr.span, context, shape)
173 ast::ExprKind::Try(..) |
174 ast::ExprKind::Field(..) |
175 ast::ExprKind::TupField(..) |
176 ast::ExprKind::MethodCall(..) => rewrite_chain(expr, context, shape),
177 ast::ExprKind::Mac(ref mac) => {
178 // Failure to rewrite a marco should not imply failure to
179 // rewrite the expression.
180 rewrite_macro(mac, None, context, shape, MacroPosition::Expression).or_else(|| {
181 wrap_str(context.snippet(expr.span),
182 context.config.max_width(),
186 ast::ExprKind::Ret(None) => {
187 wrap_str("return".to_owned(), context.config.max_width(), shape)
189 ast::ExprKind::Ret(Some(ref expr)) => {
190 rewrite_unary_prefix(context, "return ", &**expr, shape)
192 ast::ExprKind::Box(ref expr) => rewrite_unary_prefix(context, "box ", &**expr, shape),
193 ast::ExprKind::AddrOf(mutability, ref expr) => {
194 rewrite_expr_addrof(context, mutability, expr, shape)
196 ast::ExprKind::Cast(ref expr, ref ty) => {
197 rewrite_pair(&**expr, &**ty, "", " as ", "", context, shape)
199 ast::ExprKind::Type(ref expr, ref ty) => {
200 rewrite_pair(&**expr, &**ty, "", ": ", "", context, shape)
202 ast::ExprKind::Index(ref expr, ref index) => {
203 rewrite_index(&**expr, &**index, context, shape)
205 ast::ExprKind::Repeat(ref expr, ref repeats) => {
206 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
211 rewrite_pair(&**expr, &**repeats, lbr, "; ", rbr, context, shape)
213 ast::ExprKind::Range(ref lhs, ref rhs, limits) => {
214 let delim = match limits {
215 ast::RangeLimits::HalfOpen => "..",
216 ast::RangeLimits::Closed => "...",
219 match (lhs.as_ref().map(|x| &**x), rhs.as_ref().map(|x| &**x)) {
220 (Some(ref lhs), Some(ref rhs)) => {
221 let sp_delim = if context.config.spaces_around_ranges() {
222 format!(" {} ", delim)
226 rewrite_pair(&**lhs, &**rhs, "", &sp_delim, "", context, shape)
228 (None, Some(ref rhs)) => {
229 let sp_delim = if context.config.spaces_around_ranges() {
230 format!("{} ", delim)
234 rewrite_unary_prefix(context, &sp_delim, &**rhs, shape)
236 (Some(ref lhs), None) => {
237 let sp_delim = if context.config.spaces_around_ranges() {
238 format!(" {}", delim)
242 rewrite_unary_suffix(context, &sp_delim, &**lhs, shape)
244 (None, None) => wrap_str(delim.into(), context.config.max_width(), shape),
247 // We do not format these expressions yet, but they should still
248 // satisfy our width restrictions.
249 ast::ExprKind::InPlace(..) |
250 ast::ExprKind::InlineAsm(..) => {
251 wrap_str(context.snippet(expr.span),
252 context.config.max_width(),
256 result.and_then(|res| recover_comment_removed(res, expr.span, context, shape))
259 pub fn rewrite_pair<LHS, RHS>(lhs: &LHS,
264 context: &RewriteContext,
270 // Get "full width" rhs and see if it fits on the current line. This
271 // usually works fairly well since it tends to place operands of
272 // operations with high precendence close together.
273 // Note that this is non-conservative, but its just to see if it's even
274 // worth trying to put everything on one line.
275 let rhs_shape = try_opt!(shape.sub_width(suffix.len()));
276 let rhs_result = rhs.rewrite(context, rhs_shape);
278 if let Some(rhs_result) = rhs_result {
279 // This is needed in case of line break not caused by a
280 // shortage of space, but by end-of-line comments, for example.
281 if !rhs_result.contains('\n') {
282 let lhs_shape = try_opt!(shape.sub_width(prefix.len() + infix.len()));
283 let lhs_result = lhs.rewrite(context, lhs_shape);
284 if let Some(lhs_result) = lhs_result {
285 let mut result = format!("{}{}{}", prefix, lhs_result, infix);
287 let remaining_width = shape
289 .checked_sub(last_line_width(&result) + suffix.len())
292 if rhs_result.len() <= remaining_width {
293 result.push_str(&rhs_result);
294 result.push_str(suffix);
298 // Try rewriting the rhs into the remaining space.
299 let rhs_shape = shape.shrink_left(last_line_width(&result) + suffix.len());
300 if let Some(rhs_shape) = rhs_shape {
301 if let Some(rhs_result) = rhs.rewrite(context, rhs_shape) {
302 // FIXME this should always hold.
303 if rhs_result.len() <= remaining_width {
304 result.push_str(&rhs_result);
305 result.push_str(suffix);
314 // We have to use multiple lines.
316 // Re-evaluate the rhs because we have more space now:
317 let infix = infix.trim_right();
318 let lhs_budget = try_opt!(context
321 .checked_sub(shape.used_width() + prefix.len() +
323 let rhs_shape = match context.config.control_style() {
325 try_opt!(shape.sub_width(suffix.len() + prefix.len())).visual_indent(prefix.len())
327 Style::Rfc => try_opt!(shape.block_left(context.config.tab_spaces())),
330 let rhs_result = try_opt!(rhs.rewrite(context, rhs_shape));
331 let lhs_result = try_opt!(lhs.rewrite(context,
336 Some(format!("{}{}{}\n{}{}{}",
340 rhs_shape.indent.to_string(context.config),
345 pub fn rewrite_array<'a, I>(expr_iter: I,
347 context: &RewriteContext,
350 where I: Iterator<Item = &'a ast::Expr>
352 let bracket_size = if context.config.spaces_within_square_brackets() {
358 let nested_shape = match context.config.array_layout() {
359 IndentStyle::Block => shape.block().block_indent(context.config.tab_spaces()),
360 IndentStyle::Visual => {
362 .visual_indent(bracket_size)
363 .sub_width(bracket_size * 2))
367 let items = itemize_list(context.codemap,
372 |item| item.rewrite(context, nested_shape),
375 .collect::<Vec<_>>();
377 if items.is_empty() {
378 if context.config.spaces_within_square_brackets() {
379 return Some("[ ]".to_string());
381 return Some("[]".to_string());
385 let has_long_item = try_opt!(items
387 .map(|li| li.item.as_ref().map(|s| s.len() > 10))
389 |acc, x| acc.and_then(|y| x.map(|x| x || y))));
391 let tactic = match context.config.array_layout() {
392 IndentStyle::Block => {
393 // FIXME wrong shape in one-line case
394 match shape.width.checked_sub(2 * bracket_size) {
397 ListTactic::LimitedHorizontalVertical(context.config.array_width());
398 definitive_tactic(&items, tactic, width)
400 None => DefinitiveListTactic::Vertical,
403 IndentStyle::Visual => {
404 if has_long_item || items.iter().any(ListItem::is_multiline) {
405 definitive_tactic(&items,
406 ListTactic::LimitedHorizontalVertical(context
411 DefinitiveListTactic::Mixed
416 let fmt = ListFormatting {
419 trailing_separator: SeparatorTactic::Never,
421 ends_with_newline: false,
422 config: context.config,
424 let list_str = try_opt!(write_list(&items, &fmt));
426 let result = if context.config.array_layout() == IndentStyle::Visual ||
427 tactic != DefinitiveListTactic::Vertical {
428 if context.config.spaces_within_square_brackets() && list_str.len() > 0 {
429 format!("[ {} ]", list_str)
431 format!("[{}]", list_str)
434 format!("[\n{}{},\n{}]",
435 nested_shape.indent.to_string(context.config),
437 shape.block().indent.to_string(context.config))
443 // This functions is pretty messy because of the rules around closures and blocks:
444 // FIXME - the below is probably no longer true in full.
445 // * if there is a return type, then there must be braces,
446 // * given a closure with braces, whether that is parsed to give an inner block
447 // or not depends on if there is a return type and if there are statements
449 // * if the first expression in the body ends with a block (i.e., is a
450 // statement without needing a semi-colon), then adding or removing braces
451 // can change whether it is treated as an expression or statement.
452 fn rewrite_closure(capture: ast::CaptureBy,
453 fn_decl: &ast::FnDecl,
456 context: &RewriteContext,
459 let mover = if capture == ast::CaptureBy::Value {
464 // 4 = "|| {".len(), which is overconservative when the closure consists of
465 // a single expression.
466 let nested_shape = try_opt!(try_opt!(shape.shrink_left(mover.len())).sub_width(4));
469 let argument_offset = nested_shape.indent + 1;
470 let arg_shape = try_opt!(nested_shape.shrink_left(1)).visual_indent(0);
471 let ret_str = try_opt!(fn_decl.output.rewrite(context, arg_shape));
473 let arg_items = itemize_list(context.codemap,
474 fn_decl.inputs.iter(),
476 |arg| span_lo_for_arg(arg),
477 |arg| span_hi_for_arg(arg),
478 |arg| arg.rewrite(context, arg_shape),
479 context.codemap.span_after(span, "|"),
481 let item_vec = arg_items.collect::<Vec<_>>();
482 // 1 = space between arguments and return type.
483 let horizontal_budget = nested_shape
485 .checked_sub(ret_str.len() + 1)
487 let tactic = definitive_tactic(&item_vec, ListTactic::HorizontalVertical, horizontal_budget);
488 let arg_shape = match tactic {
489 DefinitiveListTactic::Horizontal => try_opt!(arg_shape.sub_width(ret_str.len() + 1)),
493 let fmt = ListFormatting {
496 trailing_separator: SeparatorTactic::Never,
498 ends_with_newline: false,
499 config: context.config,
501 let list_str = try_opt!(write_list(&item_vec, &fmt));
502 let mut prefix = format!("{}|{}|", mover, list_str);
504 if !ret_str.is_empty() {
505 if prefix.contains('\n') {
507 prefix.push_str(&argument_offset.to_string(context.config));
511 prefix.push_str(&ret_str);
514 // 1 = space between `|...|` and body.
515 let extra_offset = extra_offset(&prefix, shape) + 1;
516 let body_shape = try_opt!(shape.sub_width(extra_offset)).add_offset(extra_offset);
518 if let ast::ExprKind::Block(ref block) = body.node {
519 // The body of the closure is an empty block.
520 if block.stmts.is_empty() && !block_contains_comment(block, context.codemap) {
521 return Some(format!("{} {{}}", prefix));
524 // Figure out if the block is necessary.
525 let needs_block = block.rules != ast::BlockCheckMode::Default ||
526 block.stmts.len() > 1 || context.inside_macro ||
527 block_contains_comment(block, context.codemap) ||
528 prefix.contains('\n');
530 if ret_str.is_empty() && !needs_block {
531 // lock.stmts.len() == 1
532 if let Some(ref expr) = stmt_expr(&block.stmts[0]) {
533 if let Some(rw) = rewrite_closure_expr(expr, &prefix, context, body_shape) {
540 // We need braces, but we might still prefer a one-liner.
541 let stmt = &block.stmts[0];
542 // 4 = braces and spaces.
543 if let Some(body_shape) = body_shape.sub_width(4) {
544 // Checks if rewrite succeeded and fits on a single line.
545 if let Some(rewrite) = and_one_line(stmt.rewrite(context, body_shape)) {
546 return Some(format!("{} {{ {} }}", prefix, rewrite));
551 // Either we require a block, or tried without and failed.
552 return rewrite_closure_block(&block, prefix, context, body_shape);
555 if let Some(rw) = rewrite_closure_expr(body, &prefix, context, body_shape) {
559 // The closure originally had a non-block expression, but we can't fit on
560 // one line, so we'll insert a block.
561 let block = ast::Block {
562 stmts: vec![ast::Stmt {
563 id: ast::NodeId::new(0),
564 node: ast::StmtKind::Expr(ptr::P(body.clone())),
567 id: ast::NodeId::new(0),
568 rules: ast::BlockCheckMode::Default,
571 return rewrite_closure_block(&block, prefix, context, body_shape);
573 fn rewrite_closure_expr(expr: &ast::Expr,
575 context: &RewriteContext,
578 let mut rewrite = expr.rewrite(context, shape);
579 if classify::expr_requires_semi_to_be_stmt(left_most_sub_expr(expr)) {
580 rewrite = and_one_line(rewrite);
582 rewrite.map(|rw| format!("{} {}", prefix, rw))
585 fn rewrite_closure_block(block: &ast::Block,
587 context: &RewriteContext,
590 // Start with visual indent, then fall back to block indent if the
592 if let Some(block_str) = block.rewrite(&context, shape) {
593 let block_threshold = context.config.closure_block_indent_threshold();
594 if block_threshold < 0 || block_str.matches('\n').count() <= block_threshold as usize {
595 if let Some(block_str) = block_str.rewrite(context, shape) {
596 return Some(format!("{} {}", prefix, block_str));
601 // The body of the closure is big enough to be block indented, that
602 // means we must re-format.
603 let block_shape = shape.block().with_max_width(context.config);
604 let block_str = try_opt!(block.rewrite(&context, block_shape));
605 Some(format!("{} {}",
607 try_opt!(block_str.rewrite(context, block_shape))))
611 fn and_one_line(x: Option<String>) -> Option<String> {
612 x.and_then(|x| if x.contains('\n') { None } else { Some(x) })
615 fn nop_block_collapse(block_str: Option<String>, budget: usize) -> Option<String> {
616 debug!("nop_block_collapse {:?} {}", block_str, budget);
617 block_str.map(|block_str| if block_str.starts_with('{') && budget >= 2 &&
618 (block_str[1..].find(|c: char| !c.is_whitespace()).unwrap() ==
619 block_str.len() - 2) {
626 impl Rewrite for ast::Block {
627 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
628 // shape.width is used only for the single line case: either the empty block `{}`,
629 // or an unsafe expression `unsafe { e }`.
631 if self.stmts.is_empty() && !block_contains_comment(self, context.codemap) &&
633 return Some("{}".to_owned());
636 // If a block contains only a single-line comment, then leave it on one line.
637 let user_str = context.snippet(self.span);
638 let user_str = user_str.trim();
639 if user_str.starts_with('{') && user_str.ends_with('}') {
640 let comment_str = user_str[1..user_str.len() - 1].trim();
641 if self.stmts.is_empty() && !comment_str.contains('\n') &&
642 !comment_str.starts_with("//") &&
643 comment_str.len() + 4 <= shape.width {
644 return Some(format!("{{ {} }}", comment_str));
648 let mut visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
649 visitor.block_indent = shape.indent;
651 let prefix = match self.rules {
652 ast::BlockCheckMode::Unsafe(..) => {
653 let snippet = context.snippet(self.span);
654 let open_pos = try_opt!(snippet.find_uncommented("{"));
655 visitor.last_pos = self.span.lo + BytePos(open_pos as u32);
657 // Extract comment between unsafe and block start.
658 let trimmed = &snippet[6..open_pos].trim();
660 let prefix = if !trimmed.is_empty() {
661 // 9 = "unsafe {".len(), 7 = "unsafe ".len()
662 let budget = try_opt!(shape.width.checked_sub(9));
663 format!("unsafe {} ",
664 try_opt!(rewrite_comment(trimmed,
666 Shape::legacy(budget, shape.indent + 7),
672 if is_simple_block(self, context.codemap) && prefix.len() < shape.width {
674 self.stmts[0].rewrite(context,
675 Shape::legacy(shape.width - prefix.len(),
677 let expr_str = try_opt!(expr_str);
678 let result = format!("{}{{ {} }}", prefix, expr_str);
679 if result.len() <= shape.width && !result.contains('\n') {
686 ast::BlockCheckMode::Default => {
687 visitor.last_pos = self.span.lo;
693 visitor.visit_block(self);
694 if visitor.failed && shape.indent.alignment != 0 {
695 self.rewrite(context,
696 Shape::indented(shape.indent.block_only(), context.config))
698 Some(format!("{}{}", prefix, visitor.buffer))
703 impl Rewrite for ast::Stmt {
704 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
705 let result = match self.node {
706 ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
707 ast::StmtKind::Expr(ref ex) |
708 ast::StmtKind::Semi(ref ex) => {
709 let suffix = if semicolon_for_stmt(self) { ";" } else { "" };
713 ast::StmtKind::Expr(_) => ExprType::SubExpression,
714 ast::StmtKind::Semi(_) => ExprType::Statement,
718 try_opt!(shape.sub_width(suffix.len())))
721 ast::StmtKind::Mac(..) |
722 ast::StmtKind::Item(..) => None,
724 result.and_then(|res| recover_comment_removed(res, self.span, context, shape))
728 // Abstraction over control flow expressions
730 struct ControlFlow<'a> {
731 cond: Option<&'a ast::Expr>,
732 block: &'a ast::Block,
733 else_block: Option<&'a ast::Expr>,
734 label: Option<ast::SpannedIdent>,
735 pat: Option<&'a ast::Pat>,
739 allow_single_line: bool,
740 // True if this is an `if` expression in an `else if` :-( hacky
745 impl<'a> ControlFlow<'a> {
746 fn new_if(cond: &'a ast::Expr,
747 pat: Option<&'a ast::Pat>,
748 block: &'a ast::Block,
749 else_block: Option<&'a ast::Expr>,
750 allow_single_line: bool,
757 else_block: else_block,
766 allow_single_line: allow_single_line,
767 nested_if: nested_if,
772 fn new_loop(block: &'a ast::Block,
773 label: Option<ast::SpannedIdent>,
785 allow_single_line: false,
791 fn new_while(pat: Option<&'a ast::Pat>,
793 block: &'a ast::Block,
794 label: Option<ast::SpannedIdent>,
809 allow_single_line: false,
815 fn new_for(pat: &'a ast::Pat,
817 block: &'a ast::Block,
818 label: Option<ast::SpannedIdent>,
830 allow_single_line: false,
836 fn rewrite_single_line(&self,
838 context: &RewriteContext,
841 assert!(self.allow_single_line);
842 let else_block = try_opt!(self.else_block);
843 let fixed_cost = self.keyword.len() + " { } else { }".len();
845 if let ast::ExprKind::Block(ref else_node) = else_block.node {
846 if !is_simple_block(self.block, context.codemap) ||
847 !is_simple_block(else_node, context.codemap) ||
848 pat_expr_str.contains('\n') {
852 let new_width = try_opt!(width.checked_sub(pat_expr_str.len() + fixed_cost));
853 let expr = &self.block.stmts[0];
854 let if_str = try_opt!(expr.rewrite(context, Shape::legacy(new_width, Indent::empty())));
856 let new_width = try_opt!(new_width.checked_sub(if_str.len()));
857 let else_expr = &else_node.stmts[0];
858 let else_str = try_opt!(else_expr.rewrite(context,
859 Shape::legacy(new_width, Indent::empty())));
861 if if_str.contains('\n') || else_str.contains('\n') {
865 let result = format!("{} {} {{ {} }} else {{ {} }}",
871 if result.len() <= width {
880 impl<'a> Rewrite for ControlFlow<'a> {
881 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
882 debug!("ControlFlow::rewrite {:?} {:?}", self, shape);
883 let constr_shape = if self.nested_if {
884 // We are part of an if-elseif-else chain. Our constraints are tightened.
885 // 7 = "} else " .len()
886 try_opt!(shape.shrink_left(7))
891 let label_string = rewrite_label(self.label);
892 // 1 = space after keyword.
893 let add_offset = self.keyword.len() + label_string.len() + 1;
895 let pat_expr_string = match self.cond {
897 let mut cond_shape = match context.config.control_style() {
898 Style::Default => try_opt!(constr_shape.shrink_left(add_offset)),
899 Style::Rfc => constr_shape,
901 if context.config.control_brace_style() != ControlBraceStyle::AlwaysNextLine {
903 cond_shape = try_opt!(cond_shape.sub_width(2));
906 try_opt!(rewrite_pat_expr(context,
913 None => String::new(),
916 let force_newline_brace = context.config.control_style() == Style::Rfc &&
917 pat_expr_string.contains('\n');
919 // Try to format if-else on single line.
920 if self.allow_single_line && context.config.single_line_if_else_max_width() > 0 {
921 let trial = self.rewrite_single_line(&pat_expr_string, context, shape.width);
923 if trial.is_some() &&
924 trial.as_ref().unwrap().len() <= context.config.single_line_if_else_max_width() {
929 let used_width = if pat_expr_string.contains('\n') {
930 last_line_width(&pat_expr_string)
932 // 2 = spaces after keyword and condition.
933 label_string.len() + self.keyword.len() + pat_expr_string.len() + 2
936 let block_width = shape.width.checked_sub(used_width).unwrap_or(0);
937 // This is used only for the empty block case: `{}`. So, we use 1 if we know
938 // we should avoid the single line case.
939 let block_width = if self.else_block.is_some() || self.nested_if {
945 let block_shape = Shape {
949 let block_str = try_opt!(self.block.rewrite(context, block_shape));
951 let cond_span = if let Some(cond) = self.cond {
954 mk_sp(self.block.span.lo, self.block.span.lo)
957 // for event in event
958 let between_kwd_cond =
959 mk_sp(context.codemap.span_after(self.span, self.keyword.trim()),
961 .map_or(cond_span.lo, |p| if self.matcher.is_empty() {
964 context.codemap.span_before(self.span, self.matcher.trim())
967 let between_kwd_cond_comment = extract_comment(between_kwd_cond, context, shape);
969 let after_cond_comment =
970 extract_comment(mk_sp(cond_span.hi, self.block.span.lo), context, shape);
972 let alt_block_sep = String::from("\n") +
973 &shape.indent.block_only().to_string(context.config);
974 let block_sep = if self.cond.is_none() && between_kwd_cond_comment.is_some() {
976 } else if context.config.control_brace_style() == ControlBraceStyle::AlwaysNextLine ||
977 force_newline_brace {
978 alt_block_sep.as_str()
983 let mut result = format!("{}{}{}{}{}{}",
986 between_kwd_cond_comment
988 .map_or(if pat_expr_string.is_empty() ||
989 pat_expr_string.starts_with('\n') {
996 after_cond_comment.as_ref().map_or(block_sep, |s| &**s),
999 if let Some(else_block) = self.else_block {
1000 let shape = Shape::indented(shape.indent, context.config);
1001 let mut last_in_chain = false;
1002 let rewrite = match else_block.node {
1003 // If the else expression is another if-else expression, prevent it
1004 // from being formatted on a single line.
1005 // Note how we're passing the original shape, as the
1006 // cost of "else" should not cascade.
1007 ast::ExprKind::IfLet(ref pat, ref cond, ref if_block, ref next_else_block) => {
1008 ControlFlow::new_if(cond,
1011 next_else_block.as_ref().map(|e| &**e),
1014 mk_sp(else_block.span.lo, self.span.hi))
1015 .rewrite(context, shape)
1017 ast::ExprKind::If(ref cond, ref if_block, ref next_else_block) => {
1018 ControlFlow::new_if(cond,
1021 next_else_block.as_ref().map(|e| &**e),
1024 mk_sp(else_block.span.lo, self.span.hi))
1025 .rewrite(context, shape)
1028 last_in_chain = true;
1029 // When rewriting a block, the width is only used for single line
1030 // blocks, passing 1 lets us avoid that.
1031 let else_shape = Shape {
1032 width: min(1, shape.width),
1035 else_block.rewrite(context, else_shape)
1039 let between_kwd_else_block =
1040 mk_sp(self.block.span.hi,
1043 .span_before(mk_sp(self.block.span.hi, else_block.span.lo), "else"));
1044 let between_kwd_else_block_comment =
1045 extract_comment(between_kwd_else_block, context, shape);
1047 let after_else = mk_sp(context.codemap.span_after(mk_sp(self.block.span.hi,
1048 else_block.span.lo),
1050 else_block.span.lo);
1051 let after_else_comment = extract_comment(after_else, context, shape);
1053 let between_sep = match context.config.control_brace_style() {
1054 ControlBraceStyle::AlwaysNextLine |
1055 ControlBraceStyle::ClosingNextLine => &*alt_block_sep,
1056 ControlBraceStyle::AlwaysSameLine => " ",
1058 let after_sep = match context.config.control_brace_style() {
1059 ControlBraceStyle::AlwaysNextLine if last_in_chain => &*alt_block_sep,
1062 try_opt!(write!(&mut result,
1064 between_kwd_else_block_comment
1066 .map_or(between_sep, |s| &**s),
1067 after_else_comment.as_ref().map_or(after_sep, |s| &**s))
1069 result.push_str(&try_opt!(rewrite));
1076 fn rewrite_label(label: Option<ast::SpannedIdent>) -> String {
1078 Some(ident) => format!("{}: ", ident.node),
1079 None => "".to_owned(),
1083 fn extract_comment(span: Span, context: &RewriteContext, shape: Shape) -> Option<String> {
1084 let comment_str = context.snippet(span);
1085 if contains_comment(&comment_str) {
1086 let comment = try_opt!(rewrite_comment(comment_str.trim(), false, shape, context.config));
1087 Some(format!("\n{indent}{}\n{indent}",
1089 indent = shape.indent.to_string(context.config)))
1095 fn block_contains_comment(block: &ast::Block, codemap: &CodeMap) -> bool {
1096 let snippet = codemap.span_to_snippet(block.span).unwrap();
1097 contains_comment(&snippet)
1100 // Checks that a block contains no statements, an expression and no comments.
1101 // FIXME: incorrectly returns false when comment is contained completely within
1103 pub fn is_simple_block(block: &ast::Block, codemap: &CodeMap) -> bool {
1104 (block.stmts.len() == 1 && stmt_is_expr(&block.stmts[0]) &&
1105 !block_contains_comment(block, codemap))
1108 /// Checks whether a block contains at most one statement or expression, and no comments.
1109 pub fn is_simple_block_stmt(block: &ast::Block, codemap: &CodeMap) -> bool {
1110 block.stmts.len() <= 1 && !block_contains_comment(block, codemap)
1113 /// Checks whether a block contains no statements, expressions, or comments.
1114 pub fn is_empty_block(block: &ast::Block, codemap: &CodeMap) -> bool {
1115 block.stmts.is_empty() && !block_contains_comment(block, codemap)
1118 pub fn stmt_is_expr(stmt: &ast::Stmt) -> bool {
1120 ast::StmtKind::Expr(..) => true,
1125 fn is_unsafe_block(block: &ast::Block) -> bool {
1126 if let ast::BlockCheckMode::Unsafe(..) = block.rules {
1133 // inter-match-arm-comment-rules:
1134 // - all comments following a match arm before the start of the next arm
1135 // are about the second arm
1136 fn rewrite_match_arm_comment(context: &RewriteContext,
1139 arm_indent_str: &str)
1141 // The leading "," is not part of the arm-comment
1142 let missed_str = match missed_str.find_uncommented(",") {
1143 Some(n) => &missed_str[n + 1..],
1144 None => &missed_str[..],
1147 let mut result = String::new();
1148 // any text not preceeded by a newline is pushed unmodified to the block
1149 let first_brk = missed_str.find(|c: char| c == '\n').unwrap_or(0);
1150 result.push_str(&missed_str[..first_brk]);
1151 let missed_str = &missed_str[first_brk..]; // If missed_str had one newline, it starts with it
1153 let first = missed_str
1154 .find(|c: char| !c.is_whitespace())
1155 .unwrap_or(missed_str.len());
1156 if missed_str[..first].chars().filter(|c| c == &'\n').count() >= 2 {
1157 // Excessive vertical whitespace before comment should be preserved
1158 // FIXME handle vertical whitespace better
1161 let missed_str = missed_str[first..].trim();
1162 if !missed_str.is_empty() {
1163 let comment = try_opt!(rewrite_comment(&missed_str, false, shape, context.config));
1165 result.push_str(arm_indent_str);
1166 result.push_str(&comment);
1172 fn rewrite_match(context: &RewriteContext,
1178 if arms.is_empty() {
1183 let cond_shape = try_opt!(shape.shrink_left(6));
1184 let cond_shape = try_opt!(cond_shape.sub_width(2));
1185 let cond_str = try_opt!(cond.rewrite(context, cond_shape));
1186 let alt_block_sep = String::from("\n") + &shape.indent.block_only().to_string(context.config);
1187 let block_sep = match context.config.control_brace_style() {
1188 ControlBraceStyle::AlwaysSameLine => " ",
1189 _ => alt_block_sep.as_str(),
1191 let mut result = format!("match {}{}{{", cond_str, block_sep);
1193 let arm_shape = if context.config.indent_match_arms() {
1194 shape.block_indent(context.config.tab_spaces())
1196 shape.block_indent(0)
1199 let arm_indent_str = arm_shape.indent.to_string(context.config);
1201 let open_brace_pos = context
1203 .span_after(mk_sp(cond.span.hi, arm_start_pos(&arms[0])), "{");
1205 for (i, arm) in arms.iter().enumerate() {
1206 // Make sure we get the stuff between arms.
1207 let missed_str = if i == 0 {
1208 context.snippet(mk_sp(open_brace_pos, arm_start_pos(arm)))
1210 context.snippet(mk_sp(arm_end_pos(&arms[i - 1]), arm_start_pos(arm)))
1213 try_opt!(rewrite_match_arm_comment(context, &missed_str, arm_shape, &arm_indent_str));
1214 result.push_str(&comment);
1216 result.push_str(&arm_indent_str);
1218 let arm_str = arm.rewrite(&context, arm_shape.with_max_width(context.config));
1219 if let Some(ref arm_str) = arm_str {
1220 result.push_str(arm_str);
1222 // We couldn't format the arm, just reproduce the source.
1223 let snippet = context.snippet(mk_sp(arm_start_pos(arm), arm_end_pos(arm)));
1224 result.push_str(&snippet);
1225 result.push_str(arm_comma(context.config, &arm.body));
1228 // BytePos(1) = closing match brace.
1229 let last_span = mk_sp(arm_end_pos(&arms[arms.len() - 1]), span.hi - BytePos(1));
1230 let last_comment = context.snippet(last_span);
1232 try_opt!(rewrite_match_arm_comment(context, &last_comment, arm_shape, &arm_indent_str));
1233 result.push_str(&comment);
1235 result.push_str(&shape.indent.to_string(context.config));
1240 fn arm_start_pos(arm: &ast::Arm) -> BytePos {
1246 if !attrs.is_empty() {
1247 return attrs[0].span.lo;
1253 fn arm_end_pos(arm: &ast::Arm) -> BytePos {
1257 fn arm_comma(config: &Config, body: &ast::Expr) -> &'static str {
1258 if config.match_block_trailing_comma() {
1260 } else if let ast::ExprKind::Block(ref block) = body.node {
1261 if let ast::BlockCheckMode::Default = block.rules {
1272 impl Rewrite for ast::Arm {
1273 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1274 debug!("Arm::rewrite {:?} {:?}", self, shape);
1282 // FIXME this is all a bit grotty, would be nice to abstract out the
1283 // treatment of attributes.
1284 let attr_str = if !attrs.is_empty() {
1285 // We only use this visitor for the attributes, should we use it for
1287 let mut attr_visitor = FmtVisitor::from_codemap(context.parse_session, context.config);
1288 attr_visitor.block_indent = shape.indent.block_only();
1289 attr_visitor.last_pos = attrs[0].span.lo;
1290 if attr_visitor.visit_attrs(attrs) {
1291 // Attributes included a skip instruction.
1294 attr_visitor.format_missing(pats[0].span.lo);
1295 attr_visitor.buffer.to_string()
1302 let pat_shape = try_opt!(shape.sub_width(5));
1304 let pat_strs = try_opt!(pats.iter()
1305 .map(|p| p.rewrite(context, pat_shape))
1306 .collect::<Option<Vec<_>>>());
1308 let all_simple = pat_strs.iter().all(|p| pat_is_simple(p));
1309 let items: Vec<_> = pat_strs.into_iter().map(ListItem::from_str).collect();
1310 let fmt = ListFormatting {
1311 tactic: if all_simple {
1312 DefinitiveListTactic::Mixed
1314 DefinitiveListTactic::Vertical
1317 trailing_separator: SeparatorTactic::Never,
1319 ends_with_newline: false,
1320 config: context.config,
1322 let pats_str = try_opt!(write_list(items, &fmt));
1324 let guard_shape = if pats_str.contains('\n') {
1325 shape.with_max_width(context.config)
1330 let guard_str = try_opt!(rewrite_guard(context,
1333 trimmed_last_line_width(&pats_str)));
1335 let pats_str = format!("{}{}", pats_str, guard_str);
1337 let (mut extend, body) = match body.node {
1338 ast::ExprKind::Block(ref block) if !is_unsafe_block(block) &&
1339 is_simple_block(block, context.codemap) &&
1340 context.config.wrap_match_arms() => {
1341 if let ast::StmtKind::Expr(ref expr) = block.stmts[0].node {
1347 ast::ExprKind::Call(_, ref args) => (args.len() == 1, &**body),
1348 ast::ExprKind::Closure(..) => (true, &**body),
1349 _ => (false, &**body),
1351 extend &= context.config.fn_call_style() == IndentStyle::Block;
1353 let comma = arm_comma(&context.config, body);
1354 let alt_block_sep = String::from("\n") +
1355 &shape.indent.block_only().to_string(context.config);
1357 let pat_width = extra_offset(&pats_str, shape);
1358 // Let's try and get the arm body on the same line as the condition.
1360 if shape.width > pat_width + comma.len() + 4 {
1361 let arm_shape = shape
1362 .offset_left(pat_width + 4)
1364 .sub_width(comma.len())
1366 let rewrite = nop_block_collapse(body.rewrite(context, arm_shape), arm_shape.width);
1367 let is_block = if let ast::ExprKind::Block(..) = body.node {
1374 Some(ref body_str) if (!body_str.contains('\n') &&
1375 body_str.len() <= arm_shape.width) ||
1376 !context.config.wrap_match_arms() ||
1377 (extend && first_line_width(body_str) <= arm_shape.width) ||
1379 let block_sep = match context.config.control_brace_style() {
1380 ControlBraceStyle::AlwaysNextLine if is_block => alt_block_sep.as_str(),
1384 return Some(format!("{}{} =>{}{}{}",
1385 attr_str.trim_left(),
1395 // FIXME: we're doing a second rewrite of the expr; This may not be
1397 let body_shape = try_opt!(shape.sub_width(context.config.tab_spaces()))
1398 .block_indent(context.config.tab_spaces());
1399 let next_line_body = try_opt!(nop_block_collapse(body.rewrite(context, body_shape),
1401 let indent_str = shape
1403 .block_indent(context.config)
1404 .to_string(context.config);
1405 let (body_prefix, body_suffix) = if context.config.wrap_match_arms() {
1406 if context.config.match_block_trailing_comma() {
1416 let block_sep = match context.config.control_brace_style() {
1417 ControlBraceStyle::AlwaysNextLine => alt_block_sep + body_prefix + "\n",
1418 _ if body_prefix.is_empty() => "\n".to_owned(),
1419 _ => " ".to_owned() + body_prefix + "\n",
1422 if context.config.wrap_match_arms() {
1423 Some(format!("{}{} =>{}{}{}\n{}{}",
1424 attr_str.trim_left(),
1429 shape.indent.to_string(context.config),
1432 Some(format!("{}{} =>{}{}{}{}",
1433 attr_str.trim_left(),
1443 // A pattern is simple if it is very short or it is short-ish and just a path.
1444 // E.g. `Foo::Bar` is simple, but `Foo(..)` is not.
1445 fn pat_is_simple(pat_str: &str) -> bool {
1446 pat_str.len() <= 16 ||
1447 (pat_str.len() <= 24 && pat_str.chars().all(|c| c.is_alphabetic() || c == ':'))
1450 // The `if ...` guard on a match arm.
1451 fn rewrite_guard(context: &RewriteContext,
1452 guard: &Option<ptr::P<ast::Expr>>,
1454 // The amount of space used up on this line for the pattern in
1455 // the arm (excludes offset).
1456 pattern_width: usize)
1458 if let Some(ref guard) = *guard {
1459 // First try to fit the guard string on the same line as the pattern.
1460 // 4 = ` if `, 5 = ` => {`
1461 let overhead = pattern_width + 4 + 5;
1462 if overhead < shape.width {
1463 let cond_shape = shape
1464 .shrink_left(pattern_width + 4)
1468 let cond_str = guard.rewrite(context, cond_shape);
1469 if let Some(cond_str) = cond_str {
1470 return Some(format!(" if {}", cond_str));
1474 // Not enough space to put the guard after the pattern, try a newline.
1475 let overhead = shape.indent.block_indent(context.config).width() + 4 + 5;
1476 if overhead < shape.width {
1477 let cond_str = guard.rewrite(context,
1478 Shape::legacy(shape.width - overhead,
1480 shape.indent.block_indent(context.config) +
1482 if let Some(cond_str) = cond_str {
1483 return Some(format!("\n{}if {}",
1486 .block_indent(context.config)
1487 .to_string(context.config),
1498 fn rewrite_pat_expr(context: &RewriteContext,
1499 pat: Option<&ast::Pat>,
1502 // Connecting piece between pattern and expression,
1503 // *without* trailing space.
1507 debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, pat, expr);
1508 let mut pat_string = String::new();
1509 let mut result = match pat {
1511 let matcher = if matcher.is_empty() {
1514 format!("{} ", matcher)
1516 let pat_shape = try_opt!(try_opt!(shape.shrink_left(matcher.len()))
1517 .sub_width(connector.len()));
1518 pat_string = try_opt!(pat.rewrite(context, pat_shape));
1519 format!("{}{}{}", matcher, pat_string, connector)
1521 None => String::new(),
1524 // Consider only the last line of the pat string.
1525 let extra_offset = extra_offset(&result, shape);
1527 // The expression may (partially) fit on the current line.
1528 if shape.width > extra_offset + 1 {
1529 let spacer = if pat.is_some() { " " } else { "" };
1531 let expr_shape = try_opt!(shape.offset_left(extra_offset + spacer.len()));
1532 let expr_rewrite = expr.rewrite(context, expr_shape);
1534 if let Some(expr_string) = expr_rewrite {
1535 if pat.is_none() || pat_is_simple(&pat_string) || !expr_string.contains('\n') {
1536 result.push_str(spacer);
1537 result.push_str(&expr_string);
1538 return Some(result);
1543 let nested_indent = shape.indent.block_only().block_indent(context.config);
1545 // The expression won't fit on the current line, jump to next.
1547 result.push_str(&nested_indent.to_string(context.config));
1549 let expr_rewrite = expr.rewrite(&context, Shape::indented(nested_indent, context.config));
1550 result.push_str(&try_opt!(expr_rewrite));
1555 fn rewrite_string_lit(context: &RewriteContext, span: Span, shape: Shape) -> Option<String> {
1556 let string_lit = context.snippet(span);
1558 if !context.config.format_strings() && !context.config.force_format_strings() {
1559 return Some(string_lit);
1562 if !context.config.force_format_strings() &&
1563 !string_requires_rewrite(context, span, &string_lit, shape) {
1564 return Some(string_lit);
1567 let fmt = StringFormat {
1574 config: context.config,
1577 // Remove the quote characters.
1578 let str_lit = &string_lit[1..string_lit.len() - 1];
1580 rewrite_string(str_lit, &fmt)
1583 fn string_requires_rewrite(context: &RewriteContext,
1588 if context.codemap.lookup_char_pos(span.lo).col.0 != shape.indent.width() {
1592 for (i, line) in string.lines().enumerate() {
1594 if line.len() > shape.width {
1598 if line.len() > shape.width + shape.indent.width() {
1607 pub fn rewrite_call<R>(context: &RewriteContext,
1609 args: &[ptr::P<ast::Expr>],
1616 |callee_max_width| rewrite_call_inner(context, callee, callee_max_width, args, span, shape);
1618 binary_search(1, shape.width, closure)
1621 fn rewrite_call_inner<R>(context: &RewriteContext,
1623 max_callee_width: usize,
1624 args: &[ptr::P<ast::Expr>],
1627 -> Result<String, Ordering>
1630 // FIXME using byte lens instead of char lens (and probably all over the
1632 let callee_shape = Shape {
1633 width: max_callee_width,
1636 let callee_str = callee
1637 .rewrite(context, callee_shape)
1638 .ok_or(Ordering::Greater)?;
1640 // 2 = `( `, 1 = `(`
1641 let paren_overhead = if context.config.spaces_within_parens() {
1646 let used_width = extra_offset(&callee_str, shape);
1647 let one_line_width = shape
1649 .checked_sub(used_width + 2 * paren_overhead)
1650 .ok_or(Ordering::Greater)?;
1652 // Try combining openings and closings
1653 if args.len() == 1 && context.config.fn_call_style() == IndentStyle::Block {
1654 let expr = &*args[0];
1656 ast::ExprKind::Struct(..) |
1657 ast::ExprKind::Call(..) |
1658 ast::ExprKind::Closure(..) => {
1659 let max_width = min(one_line_width, context.config.fn_call_width());
1660 let shape = Shape::legacy(max_width, shape.block().indent);
1661 if let Some(expr_str) = expr.rewrite(context, shape) {
1662 if first_line_width(&expr_str) <= max_width {
1663 return Ok(format!("{}({})", callee_str, expr_str));
1671 let nested_shape = match context.config.fn_call_style() {
1672 IndentStyle::Block => shape.block().block_left(context.config.tab_spaces()),
1673 IndentStyle::Visual => {
1675 .visual_indent(used_width + paren_overhead)
1676 .sub_width(used_width + 2 * paren_overhead)
1679 .ok_or(Ordering::Greater)?;
1681 let span_lo = context.codemap.span_after(span, "(");
1682 let span = mk_sp(span_lo, span.hi);
1684 let list_str = rewrite_call_args(context, args, span, nested_shape, one_line_width)
1685 .ok_or(Ordering::Less)?;
1687 let arg_one_line_budget = min(one_line_width, context.config.fn_call_width());
1688 let result = if context.config.fn_call_style() == IndentStyle::Visual ||
1689 (((can_be_overflowed(args) &&
1690 first_line_width(&list_str) <= arg_one_line_budget) ||
1691 !list_str.contains('\n')) &&
1692 list_str.chars().last().unwrap_or(' ') != ',') {
1693 if context.config.spaces_within_parens() && list_str.len() > 0 {
1694 format!("{}( {} )", callee_str, list_str)
1696 format!("{}({})", callee_str, list_str)
1699 format!("{}(\n{}{}\n{})",
1701 nested_shape.indent.to_string(context.config),
1703 shape.block().indent.to_string(context.config))
1709 fn can_be_overflowed(args: &[ptr::P<ast::Expr>]) -> bool {
1710 match args.last().map(|x| &x.node) {
1711 Some(&ast::ExprKind::Closure(..)) |
1712 Some(&ast::ExprKind::Block(..)) |
1713 Some(&ast::ExprKind::Match(..)) if args.len() > 1 => true,
1718 fn rewrite_call_args(context: &RewriteContext,
1719 args: &[ptr::P<ast::Expr>],
1722 one_line_width: usize)
1724 let arg_count = args.len();
1726 let items = itemize_list(context.codemap,
1729 |item| item.span.lo,
1730 |item| item.span.hi,
1731 |item| item.rewrite(context, shape),
1734 let mut item_vec: Vec<_> = items.collect();
1736 // Try letting the last argument overflow to the next line with block
1737 // indentation. If its first line fits on one line with the other arguments,
1738 // we format the function arguments horizontally.
1739 let overflow_last = can_be_overflowed(args);
1741 let mut orig_last = None;
1742 let mut placeholder = None;
1744 // Replace the last item with its first line to see if it fits with
1747 let last_arg = args.last().unwrap();
1748 let arg_shape = match last_arg.node {
1749 ast::ExprKind::Closure(..) if context.config.fn_call_style() == IndentStyle::Block => {
1750 let mut arg_shape = shape.block();
1751 arg_shape.indent.block_indent -= context.config.tab_spaces();
1756 let rewrite = args.last().unwrap().rewrite(context, arg_shape);
1758 if let Some(rewrite) = rewrite {
1759 let rewrite_first_line = Some(rewrite[..first_line_width(&rewrite)].to_owned());
1760 placeholder = Some(rewrite);
1762 swap(&mut item_vec[arg_count - 1].item, &mut orig_last);
1763 item_vec[arg_count - 1].item = rewrite_first_line;
1767 let one_line_shape = Shape {
1768 width: one_line_width,
1773 definitive_tactic(&item_vec,
1774 ListTactic::LimitedHorizontalVertical(context.config.fn_call_width()),
1777 // Replace the stub with the full overflowing last argument if the rewrite
1778 // succeeded and its first line fits with the other arguments.
1779 match (overflow_last, tactic, placeholder) {
1780 (true, DefinitiveListTactic::Horizontal, placeholder @ Some(..)) => {
1781 item_vec[arg_count - 1].item = placeholder;
1784 item_vec[arg_count - 1].item = orig_last;
1789 let mut fmt = ListFormatting {
1792 trailing_separator: if context.inside_macro ||
1793 context.config.fn_call_style() == IndentStyle::Visual ||
1795 SeparatorTactic::Never
1797 context.config.trailing_comma()
1799 shape: one_line_shape,
1800 ends_with_newline: false,
1801 config: context.config,
1804 match write_list(&item_vec, &fmt) {
1805 // If arguments do not fit in a single line and do not contain newline,
1806 // try to put it on the next line. Try this only when we are in block mode
1807 // and not rewriting macro.
1808 Some(ref s) if context.config.fn_call_style() == IndentStyle::Block &&
1809 !context.inside_macro &&
1810 (!s.contains('\n') &&
1811 (s.len() > one_line_width || s.len() > context.config.fn_call_width())) => {
1812 fmt.trailing_separator = SeparatorTactic::Vertical;
1813 write_list(&item_vec, &fmt)
1815 rewrite @ _ => rewrite,
1819 fn rewrite_paren(context: &RewriteContext, subexpr: &ast::Expr, shape: Shape) -> Option<String> {
1820 debug!("rewrite_paren, shape: {:?}", shape);
1821 // 1 is for opening paren, 2 is for opening+closing, we want to keep the closing
1822 // paren on the same line as the subexpr.
1823 let sub_shape = try_opt!(shape.sub_width(2)).visual_indent(1);
1824 let subexpr_str = subexpr.rewrite(context, sub_shape);
1825 debug!("rewrite_paren, subexpr_str: `{:?}`", subexpr_str);
1827 subexpr_str.map(|s| if context.config.spaces_within_parens() && s.len() > 0 {
1828 format!("( {} )", s)
1834 fn rewrite_index(expr: &ast::Expr,
1836 context: &RewriteContext,
1839 let expr_str = try_opt!(expr.rewrite(context, shape));
1841 let (lbr, rbr) = if context.config.spaces_within_square_brackets() {
1849 .checked_sub(expr_str.len() + lbr.len() + rbr.len())
1851 let index_str = index.rewrite(context, Shape::legacy(budget, shape.indent));
1852 if let Some(index_str) = index_str {
1853 return Some(format!("{}{}{}{}", expr_str, lbr, index_str, rbr));
1856 let indent = shape.indent.block_indent(&context.config);
1857 let indent = indent.to_string(&context.config);
1858 // FIXME this is not right, since we don't take into account that shape.width
1859 // might be reduced from max_width by something on the right.
1860 let budget = try_opt!(context
1863 .checked_sub(indent.len() + lbr.len() + rbr.len()));
1864 let index_str = try_opt!(index.rewrite(context, Shape::legacy(budget, shape.indent)));
1865 Some(format!("{}\n{}{}{}{}", expr_str, indent, lbr, index_str, rbr))
1868 fn rewrite_struct_lit<'a>(context: &RewriteContext,
1870 fields: &'a [ast::Field],
1871 base: Option<&'a ast::Expr>,
1875 debug!("rewrite_struct_lit: shape {:?}", shape);
1877 enum StructLitField<'a> {
1878 Regular(&'a ast::Field),
1879 Base(&'a ast::Expr),
1883 let path_shape = try_opt!(shape.sub_width(2));
1884 let path_str = try_opt!(rewrite_path(context, PathContext::Expr, None, path, path_shape));
1886 if fields.len() == 0 && base.is_none() {
1887 return Some(format!("{} {{}}", path_str));
1890 let field_iter = fields
1892 .map(StructLitField::Regular)
1893 .chain(base.into_iter().map(StructLitField::Base));
1895 // Foo { a: Foo } - indent is +3, width is -5.
1896 let (h_shape, v_shape) = try_opt!(struct_lit_shape(shape, context, path_str.len() + 3, 2));
1898 let span_lo = |item: &StructLitField| match *item {
1899 StructLitField::Regular(field) => field.span.lo,
1900 StructLitField::Base(expr) => {
1901 let last_field_hi = fields.last().map_or(span.lo, |field| field.span.hi);
1902 let snippet = context.snippet(mk_sp(last_field_hi, expr.span.lo));
1903 let pos = snippet.find_uncommented("..").unwrap();
1904 last_field_hi + BytePos(pos as u32)
1907 let span_hi = |item: &StructLitField| match *item {
1908 StructLitField::Regular(field) => field.span.hi,
1909 StructLitField::Base(expr) => expr.span.hi,
1911 let rewrite = |item: &StructLitField| match *item {
1912 StructLitField::Regular(field) => {
1913 // The 1 taken from the v_budget is for the comma.
1914 rewrite_field(context, field, try_opt!(v_shape.sub_width(1)))
1916 StructLitField::Base(expr) => {
1918 expr.rewrite(context, try_opt!(v_shape.shrink_left(2)))
1919 .map(|s| format!("..{}", s))
1923 let items = itemize_list(context.codemap,
1929 context.codemap.span_after(span, "{"),
1931 let item_vec = items.collect::<Vec<_>>();
1933 let tactic = struct_lit_tactic(h_shape, context, &item_vec);
1934 let nested_shape = shape_for_tactic(tactic, h_shape, v_shape);
1935 let fmt = struct_lit_formatting(nested_shape, tactic, context, base.is_some());
1937 let fields_str = try_opt!(write_list(&item_vec, &fmt));
1938 let fields_str = if context.config.struct_lit_style() == IndentStyle::Block &&
1939 (fields_str.contains('\n') ||
1940 context.config.struct_lit_multiline_style() ==
1941 MultilineStyle::ForceMulti ||
1942 fields_str.len() > h_shape.map(|s| s.width).unwrap_or(0)) {
1943 format!("\n{}{}\n{}",
1944 v_shape.indent.to_string(context.config),
1946 shape.indent.to_string(context.config))
1948 // One liner or visual indent.
1949 format!(" {} ", fields_str)
1952 Some(format!("{} {{{}}}", path_str, fields_str))
1954 // FIXME if context.config.struct_lit_style() == Visual, but we run out
1955 // of space, we should fall back to BlockIndent.
1958 pub fn type_annotation_separator(config: &Config) -> &str {
1959 colon_spaces(config.space_before_type_annotation(),
1960 config.space_after_type_annotation_colon())
1963 fn rewrite_field(context: &RewriteContext, field: &ast::Field, shape: Shape) -> Option<String> {
1964 let name = &field.ident.node.to_string();
1965 if field.is_shorthand {
1966 Some(name.to_string())
1968 let separator = type_annotation_separator(context.config);
1969 let overhead = name.len() + separator.len();
1970 let mut expr_shape = try_opt!(shape.sub_width(overhead));
1971 expr_shape.offset += overhead;
1972 let expr = field.expr.rewrite(context, expr_shape);
1974 let mut attrs_str = try_opt!((*field.attrs).rewrite(context, shape));
1975 if !attrs_str.is_empty() {
1976 attrs_str.push_str(&format!("\n{}", shape.indent.to_string(context.config)));
1980 Some(e) => Some(format!("{}{}{}{}", attrs_str, name, separator, e)),
1982 let expr_offset = shape.indent.block_indent(context.config);
1985 .rewrite(context, Shape::indented(expr_offset, context.config));
1987 format!("{}{}:\n{}{}",
1990 expr_offset.to_string(&context.config),
1998 pub fn rewrite_tuple<'a, I>(context: &RewriteContext,
2003 where I: ExactSizeIterator,
2004 <I as Iterator>::Item: Deref,
2005 <I::Item as Deref>::Target: Rewrite + Spanned + 'a
2007 debug!("rewrite_tuple {:?}", shape);
2008 // In case of length 1, need a trailing comma
2009 if items.len() == 1 {
2011 let nested_shape = try_opt!(shape.sub_width(3)).visual_indent(1);
2015 .rewrite(context, nested_shape)
2016 .map(|s| if context.config.spaces_within_parens() {
2017 format!("( {}, )", s)
2023 let list_lo = context.codemap.span_after(span, "(");
2024 let nested_shape = try_opt!(shape.sub_width(2)).visual_indent(1);
2025 let items = itemize_list(context.codemap,
2028 |item| item.span().lo,
2029 |item| item.span().hi,
2030 |item| item.rewrite(context, nested_shape),
2032 span.hi - BytePos(1));
2033 let list_str = try_opt!(format_item_list(items, nested_shape, context.config));
2035 if context.config.spaces_within_parens() && list_str.len() > 0 {
2036 Some(format!("( {} )", list_str))
2038 Some(format!("({})", list_str))
2042 pub fn rewrite_unary_prefix<R: Rewrite>(context: &RewriteContext,
2048 .rewrite(context, try_opt!(shape.offset_left(prefix.len())))
2049 .map(|r| format!("{}{}", prefix, r))
2052 // FIXME: this is probably not correct for multi-line Rewrites. we should
2053 // subtract suffix.len() from the last line budget, not the first!
2054 pub fn rewrite_unary_suffix<R: Rewrite>(context: &RewriteContext,
2060 .rewrite(context, try_opt!(shape.sub_width(suffix.len())))
2067 fn rewrite_unary_op(context: &RewriteContext,
2072 // For some reason, an UnOp is not spanned like BinOp!
2073 let operator_str = match *op {
2074 ast::UnOp::Deref => "*",
2075 ast::UnOp::Not => "!",
2076 ast::UnOp::Neg => "-",
2078 rewrite_unary_prefix(context, operator_str, expr, shape)
2081 fn rewrite_assignment(context: &RewriteContext,
2084 op: Option<&ast::BinOp>,
2087 let operator_str = match op {
2088 Some(op) => context.snippet(op.span),
2089 None => "=".to_owned(),
2092 // 1 = space between lhs and operator.
2093 let lhs_shape = try_opt!(shape.sub_width(operator_str.len() + 1));
2094 let lhs_str = format!("{} {}",
2095 try_opt!(lhs.rewrite(context, lhs_shape)),
2098 rewrite_assign_rhs(context, lhs_str, rhs, shape)
2101 // The left hand side must contain everything up to, and including, the
2102 // assignment operator.
2103 pub fn rewrite_assign_rhs<S: Into<String>>(context: &RewriteContext,
2108 let mut result = lhs.into();
2109 let last_line_width = last_line_width(&result) -
2110 if result.contains('\n') {
2111 shape.indent.width()
2115 // 1 = space between operator and rhs.
2116 let orig_shape = try_opt!(shape.block_indent(0).offset_left(last_line_width + 1));
2117 let rhs = match ex.node {
2118 ast::ExprKind::Mac(ref mac) => {
2119 match rewrite_macro(mac, None, context, orig_shape, MacroPosition::Expression) {
2120 None if !context.snippet(ex.span).contains("\n") => {
2121 context.snippet(ex.span).rewrite(context, orig_shape)
2126 _ => ex.rewrite(context, orig_shape),
2129 fn count_line_breaks(src: &str) -> usize {
2130 src.chars().filter(|&x| x == '\n').count()
2134 Some(ref new_str) if count_line_breaks(new_str) < 2 => {
2136 result.push_str(new_str);
2139 // Expression did not fit on the same line as the identifier or is
2140 // at least three lines big. Try splitting the line and see
2141 // if that works better.
2142 let new_shape = try_opt!(shape.block_left(context.config.tab_spaces()));
2143 let new_rhs = ex.rewrite(context, new_shape);
2146 match (rhs, new_rhs) {
2147 (Some(ref orig_rhs), Some(ref replacement_rhs))
2148 if count_line_breaks(orig_rhs) > count_line_breaks(replacement_rhs) + 1 ||
2149 (orig_rhs.rewrite(context, shape).is_none() &&
2150 replacement_rhs.rewrite(context, new_shape).is_some()) => {
2151 result.push_str(&format!("\n{}", new_shape.indent.to_string(context.config)));
2152 result.push_str(replacement_rhs);
2154 (None, Some(ref final_rhs)) => {
2155 result.push_str(&format!("\n{}", new_shape.indent.to_string(context.config)));
2156 result.push_str(final_rhs);
2158 (None, None) => return None,
2159 (Some(ref orig_rhs), _) => {
2161 result.push_str(orig_rhs);
2170 fn rewrite_expr_addrof(context: &RewriteContext,
2171 mutability: ast::Mutability,
2175 let operator_str = match mutability {
2176 ast::Mutability::Immutable => "&",
2177 ast::Mutability::Mutable => "&mut ",
2179 rewrite_unary_prefix(context, operator_str, expr, shape)