src/lists.rs

   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.
   4 //
   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.
  10
  11 use std::cmp;
  12 use std::iter::Peekable;
  13
  14 use syntax::codemap::{BytePos, CodeMap};
  15
  16 use {Indent, Shape};
  17 use comment::{find_comment_end, rewrite_comment, FindUncommented};
  18 use config::{Config, IndentStyle};
  19 use rewrite::RewriteContext;
  20 use utils::{first_line_width, last_line_width, mk_sp};
  21
  22 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
  23 /// Formatting tactic for lists. This will be cast down to a
  24 /// DefinitiveListTactic depending on the number and length of the items and
  25 /// their comments.
  26 pub enum ListTactic {
  27     // One item per row.
  28     Vertical,
  29     // All items on one row.
  30     Horizontal,
  31     // Try Horizontal layout, if that fails then vertical.
  32     HorizontalVertical,
  33     // HorizontalVertical with a soft limit of n characters.
  34     LimitedHorizontalVertical(usize),
  35     // Pack as many items as possible per row over (possibly) many rows.
  36     Mixed,
  37 }
  38
  39 impl_enum_serialize_and_deserialize!(ListTactic, Vertical, Horizontal, HorizontalVertical, Mixed);
  40
  41 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
  42 pub enum SeparatorTactic {
  43     Always,
  44     Never,
  45     Vertical,
  46 }
  47
  48 impl_enum_serialize_and_deserialize!(SeparatorTactic, Always, Never, Vertical);
  49
  50 impl SeparatorTactic {
  51     pub fn from_bool(b: bool) -> SeparatorTactic {
  52         if b {
  53             SeparatorTactic::Always
  54         } else {
  55             SeparatorTactic::Never
  56         }
  57     }
  58 }
  59
  60 pub struct ListFormatting<'a> {
  61     pub tactic: DefinitiveListTactic,
  62     pub separator: &'a str,
  63     pub trailing_separator: SeparatorTactic,
  64     pub shape: Shape,
  65     // Non-expressions, e.g. items, will have a new line at the end of the list.
  66     // Important for comment styles.
  67     pub ends_with_newline: bool,
  68     // Remove newlines between list elements for expressions.
  69     pub preserve_newline: bool,
  70     pub config: &'a Config,
  71 }
  72
  73 impl AsRef<ListItem> for ListItem {
  74     fn as_ref(&self) -> &ListItem {
  75         self
  76     }
  77 }
  78
  79 #[derive(PartialEq, Eq)]
  80 pub enum ListItemCommentStyle {
  81     // Try to keep the comment on the same line with the item.
  82     SameLine,
  83     // Put the comment on the previous or the next line of the item.
  84     DifferentLine,
  85     // No comment available.
  86     None,
  87 }
  88
  89 pub struct ListItem {
  90     // None for comments mean that they are not present.
  91     pub pre_comment: Option<String>,
  92     pub pre_comment_style: ListItemCommentStyle,
  93     // Item should include attributes and doc comments. None indicates a failed
  94     // rewrite.
  95     pub item: Option<String>,
  96     pub post_comment: Option<String>,
  97     // Whether there is extra whitespace before this item.
  98     pub new_lines: bool,
  99 }
 100
 101 impl ListItem {
 102     pub fn inner_as_ref(&self) -> &str {
 103         self.item.as_ref().map_or("", |s| &*s)
 104     }
 105
 106     pub fn is_multiline(&self) -> bool {
 107         self.inner_as_ref().contains('\n') || self.pre_comment.is_some() ||
 108             self.post_comment
 109                 .as_ref()
 110                 .map_or(false, |s| s.contains('\n'))
 111     }
 112
 113     pub fn has_comment(&self) -> bool {
 114         self.pre_comment
 115             .as_ref()
 116             .map_or(false, |comment| comment.starts_with("//")) ||
 117             self.post_comment
 118                 .as_ref()
 119                 .map_or(false, |comment| comment.starts_with("//"))
 120     }
 121
 122     pub fn from_str<S: Into<String>>(s: S) -> ListItem {
 123         ListItem {
 124             pre_comment: None,
 125             pre_comment_style: ListItemCommentStyle::None,
 126             item: Some(s.into()),
 127             post_comment: None,
 128             new_lines: false,
 129         }
 130     }
 131 }
 132
 133 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
 134 /// The definitive formatting tactic for lists.
 135 pub enum DefinitiveListTactic {
 136     Vertical,
 137     Horizontal,
 138     Mixed,
 139 }
 140
 141 impl DefinitiveListTactic {
 142     pub fn ends_with_newline(&self, indent_style: IndentStyle) -> bool {
 143         match indent_style {
 144             IndentStyle::Block => *self != DefinitiveListTactic::Horizontal,
 145             IndentStyle::Visual => false,
 146         }
 147     }
 148 }
 149
 150 /// The type of separator for lists.
 151 #[derive(Eq, PartialEq, Debug)]
 152 pub enum Separator {
 153     Comma,
 154     VerticalBar,
 155 }
 156
 157 impl Separator {
 158     pub fn len(&self) -> usize {
 159         match *self {
 160             // 2 = `, `
 161             Separator::Comma => 2,
 162             // 3 = ` | `
 163             Separator::VerticalBar => 3,
 164         }
 165     }
 166 }
 167
 168 pub fn definitive_tactic<I, T>(
 169     items: I,
 170     tactic: ListTactic,
 171     sep: Separator,
 172     width: usize,
 173 ) -> DefinitiveListTactic
 174 where
 175     I: IntoIterator<Item = T> + Clone,
 176     T: AsRef<ListItem>,
 177 {
 178     let pre_line_comments = items
 179         .clone()
 180         .into_iter()
 181         .any(|item| item.as_ref().has_comment());
 182
 183     let limit = match tactic {
 184         _ if pre_line_comments => return DefinitiveListTactic::Vertical,
 185         ListTactic::Mixed => return DefinitiveListTactic::Mixed,
 186         ListTactic::Horizontal => return DefinitiveListTactic::Horizontal,
 187         ListTactic::Vertical => return DefinitiveListTactic::Vertical,
 188         ListTactic::LimitedHorizontalVertical(limit) => ::std::cmp::min(width, limit),
 189         ListTactic::HorizontalVertical => width,
 190     };
 191
 192     let (sep_count, total_width) = calculate_width(items.clone());
 193     let total_sep_len = sep.len() * sep_count.checked_sub(1).unwrap_or(0);
 194     let real_total = total_width + total_sep_len;
 195
 196     if real_total <= limit && !pre_line_comments &&
 197         !items.into_iter().any(|item| item.as_ref().is_multiline())
 198     {
 199         DefinitiveListTactic::Horizontal
 200     } else {
 201         DefinitiveListTactic::Vertical
 202     }
 203 }
 204
 205 // Format a list of commented items into a string.
 206 // TODO: add unit tests
 207 pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
 208 where
 209     I: IntoIterator<Item = T> + Clone,
 210     T: AsRef<ListItem>,
 211 {
 212     let tactic = formatting.tactic;
 213     let sep_len = formatting.separator.len();
 214
 215     // Now that we know how we will layout, we can decide for sure if there
 216     // will be a trailing separator.
 217     let mut trailing_separator = needs_trailing_separator(formatting.trailing_separator, tactic);
 218     let mut result = String::new();
 219     let cloned_items = items.clone();
 220     let mut iter = items.into_iter().enumerate().peekable();
 221     let mut item_max_width: Option<usize> = None;
 222
 223     let mut line_len = 0;
 224     let indent_str = &formatting.shape.indent.to_string(formatting.config);
 225     while let Some((i, item)) = iter.next() {
 226         let item = item.as_ref();
 227         let inner_item = try_opt!(item.item.as_ref());
 228         let first = i == 0;
 229         let last = iter.peek().is_none();
 230         let mut separate = !last || trailing_separator;
 231         let item_sep_len = if separate { sep_len } else { 0 };
 232
 233         // Item string may be multi-line. Its length (used for block comment alignment)
 234         // should be only the length of the last line.
 235         let item_last_line = if item.is_multiline() {
 236             inner_item.lines().last().unwrap_or("")
 237         } else {
 238             inner_item.as_ref()
 239         };
 240         let mut item_last_line_width = item_last_line.len() + item_sep_len;
 241         if item_last_line.starts_with(indent_str) {
 242             item_last_line_width -= indent_str.len();
 243         }
 244
 245         match tactic {
 246             DefinitiveListTactic::Horizontal if !first => {
 247                 result.push(' ');
 248             }
 249             DefinitiveListTactic::Vertical if !first => {
 250                 result.push('\n');
 251                 result.push_str(indent_str);
 252             }
 253             DefinitiveListTactic::Mixed => {
 254                 let total_width = total_item_width(item) + item_sep_len;
 255
 256                 // 1 is space between separator and item.
 257                 if line_len > 0 && line_len + 1 + total_width > formatting.shape.width {
 258                     result.push('\n');
 259                     result.push_str(indent_str);
 260                     line_len = 0;
 261                     if tactic == DefinitiveListTactic::Mixed && formatting.ends_with_newline {
 262                         if last {
 263                             separate = true;
 264                         } else {
 265                             trailing_separator = true;
 266                         }
 267                     }
 268                 }
 269
 270                 if line_len > 0 {
 271                     result.push(' ');
 272                     line_len += 1;
 273                 }
 274
 275                 line_len += total_width;
 276             }
 277             _ => {}
 278         }
 279
 280         // Pre-comments
 281         if let Some(ref comment) = item.pre_comment {
 282             // Block style in non-vertical mode.
 283             let block_mode = tactic != DefinitiveListTactic::Vertical;
 284             // Width restriction is only relevant in vertical mode.
 285             let comment = try_opt!(rewrite_comment(
 286                 comment,
 287                 block_mode,
 288                 formatting.shape,
 289                 formatting.config,
 290             ));
 291             result.push_str(&comment);
 292
 293             if tactic == DefinitiveListTactic::Vertical {
 294                 // We cannot keep pre-comments on the same line if the comment if normalized.
 295                 let keep_comment = if formatting.config.normalize_comments() {
 296                     false
 297                 } else if item.pre_comment_style == ListItemCommentStyle::DifferentLine {
 298                     false
 299                 } else {
 300                     // We will try to keep the comment on the same line with the item here.
 301                     // 1 = ` `
 302                     let total_width = total_item_width(item) + item_sep_len + 1;
 303                     total_width <= formatting.shape.width
 304                 };
 305                 if keep_comment {
 306                     result.push(' ');
 307                 } else {
 308                     result.push('\n');
 309                     result.push_str(indent_str);
 310                 }
 311             } else {
 312                 result.push(' ');
 313             }
 314             item_max_width = None;
 315         }
 316
 317         result.push_str(&inner_item[..]);
 318
 319         // Post-comments
 320         if tactic != DefinitiveListTactic::Vertical && item.post_comment.is_some() {
 321             let comment = item.post_comment.as_ref().unwrap();
 322             let formatted_comment = try_opt!(rewrite_comment(
 323                 comment,
 324                 true,
 325                 Shape::legacy(formatting.shape.width, Indent::empty()),
 326                 formatting.config,
 327             ));
 328
 329             result.push(' ');
 330             result.push_str(&formatted_comment);
 331         }
 332
 333         if separate {
 334             result.push_str(formatting.separator);
 335         }
 336
 337         if tactic == DefinitiveListTactic::Vertical && item.post_comment.is_some() {
 338             let comment = item.post_comment.as_ref().unwrap();
 339             let overhead = last_line_width(&result) + first_line_width(comment.trim());
 340
 341             let rewrite_post_comment = |item_max_width: &mut Option<usize>| {
 342                 if item_max_width.is_none() && !last && !inner_item.contains('\n') {
 343                     *item_max_width = Some(max_width_of_item_with_post_comment(
 344                         &cloned_items,
 345                         i,
 346                         overhead,
 347                         formatting.config.max_width(),
 348                     ));
 349                 }
 350                 let overhead = if let &mut Some(max_width) = item_max_width {
 351                     max_width + 2
 352                 } else {
 353                     // 1 = space between item and comment.
 354                     item_last_line_width + 1
 355                 };
 356                 let width = formatting.shape.width.checked_sub(overhead).unwrap_or(1);
 357                 let offset = formatting.shape.indent + overhead;
 358                 let comment_shape = Shape::legacy(width, offset);
 359
 360                 // Use block-style only for the last item or multiline comments.
 361                 let block_style = !formatting.ends_with_newline && last ||
 362                     comment.trim().contains('\n') ||
 363                     comment.trim().len() > width;
 364
 365                 rewrite_comment(comment, block_style, comment_shape, formatting.config)
 366             };
 367
 368             let mut formatted_comment = try_opt!(rewrite_post_comment(&mut item_max_width));
 369
 370             if !formatted_comment.starts_with('\n') {
 371                 let mut comment_alignment =
 372                     post_comment_alignment(item_max_width, inner_item.len());
 373                 if first_line_width(&formatted_comment) + last_line_width(&result) +
 374                     comment_alignment + 1 > formatting.config.max_width()
 375                 {
 376                     item_max_width = None;
 377                     formatted_comment = try_opt!(rewrite_post_comment(&mut item_max_width));
 378                     comment_alignment = post_comment_alignment(item_max_width, inner_item.len());
 379                 }
 380                 for _ in 0..(comment_alignment + 1) {
 381                     result.push(' ');
 382                 }
 383                 // An additional space for the missing trailing separator.
 384                 if last && item_max_width.is_some() && !separate && !formatting.separator.is_empty()
 385                 {
 386                     result.push(' ');
 387                 }
 388             }
 389             if formatted_comment.contains('\n') {
 390                 item_max_width = None;
 391             }
 392             result.push_str(&formatted_comment);
 393         } else {
 394             item_max_width = None;
 395         }
 396
 397         if formatting.preserve_newline && !last && tactic == DefinitiveListTactic::Vertical &&
 398             item.new_lines
 399         {
 400             item_max_width = None;
 401             result.push('\n');
 402         }
 403     }
 404
 405     Some(result)
 406 }
 407
 408 fn max_width_of_item_with_post_comment<I, T>(
 409     items: &I,
 410     i: usize,
 411     overhead: usize,
 412     max_budget: usize,
 413 ) -> usize
 414 where
 415     I: IntoIterator<Item = T> + Clone,
 416     T: AsRef<ListItem>,
 417 {
 418     let mut max_width = 0;
 419     let mut first = true;
 420     for item in items.clone().into_iter().skip(i) {
 421         let item = item.as_ref();
 422         let inner_item_width = item.inner_as_ref().len();
 423         if !first &&
 424             (item.is_multiline() || !item.post_comment.is_some() ||
 425                 inner_item_width + overhead > max_budget)
 426         {
 427             return max_width;
 428         }
 429         if max_width < inner_item_width {
 430             max_width = inner_item_width;
 431         }
 432         if item.new_lines {
 433             return max_width;
 434         }
 435         first = false;
 436     }
 437     max_width
 438 }
 439
 440 fn post_comment_alignment(item_max_width: Option<usize>, inner_item_len: usize) -> usize {
 441     item_max_width
 442         .and_then(|max_line_width| max_line_width.checked_sub(inner_item_len))
 443         .unwrap_or(0)
 444 }
 445
 446 pub struct ListItems<'a, I, F1, F2, F3>
 447 where
 448     I: Iterator,
 449 {
 450     codemap: &'a CodeMap,
 451     inner: Peekable<I>,
 452     get_lo: F1,
 453     get_hi: F2,
 454     get_item_string: F3,
 455     prev_span_end: BytePos,
 456     next_span_start: BytePos,
 457     terminator: &'a str,
 458     leave_last: bool,
 459 }
 460
 461 impl<'a, T, I, F1, F2, F3> Iterator for ListItems<'a, I, F1, F2, F3>
 462 where
 463     I: Iterator<Item = T>,
 464     F1: Fn(&T) -> BytePos,
 465     F2: Fn(&T) -> BytePos,
 466     F3: Fn(&T) -> Option<String>,
 467 {
 468     type Item = ListItem;
 469
 470     fn next(&mut self) -> Option<Self::Item> {
 471         let white_space: &[_] = &[' ', '\t'];
 472
 473         self.inner.next().map(|item| {
 474             let mut new_lines = false;
 475             // Pre-comment
 476             let pre_snippet = self.codemap
 477                 .span_to_snippet(mk_sp(self.prev_span_end, (self.get_lo)(&item)))
 478                 .unwrap();
 479             let trimmed_pre_snippet = pre_snippet.trim();
 480             let has_single_line_comment = trimmed_pre_snippet.starts_with("//");
 481             let has_block_comment = trimmed_pre_snippet.starts_with("/*");
 482             let (pre_comment, pre_comment_style) = if has_single_line_comment {
 483                 (
 484                     Some(trimmed_pre_snippet.to_owned()),
 485                     ListItemCommentStyle::DifferentLine,
 486                 )
 487             } else if has_block_comment {
 488                 let comment_end = pre_snippet.chars().rev().position(|c| c == '/').unwrap();
 489                 if pre_snippet
 490                     .chars()
 491                     .rev()
 492                     .take(comment_end + 1)
 493                     .find(|c| *c == '\n')
 494                     .is_some()
 495                 {
 496                     (
 497                         Some(trimmed_pre_snippet.to_owned()),
 498                         ListItemCommentStyle::DifferentLine,
 499                     )
 500                 } else {
 501                     (
 502                         Some(trimmed_pre_snippet.to_owned()),
 503                         ListItemCommentStyle::SameLine,
 504                     )
 505                 }
 506             } else {
 507                 (None, ListItemCommentStyle::None)
 508             };
 509
 510             // Post-comment
 511             let next_start = match self.inner.peek() {
 512                 Some(next_item) => (self.get_lo)(next_item),
 513                 None => self.next_span_start,
 514             };
 515             let post_snippet = self.codemap
 516                 .span_to_snippet(mk_sp((self.get_hi)(&item), next_start))
 517                 .unwrap();
 518
 519             let comment_end = match self.inner.peek() {
 520                 Some(..) => {
 521                     let mut block_open_index = post_snippet.find("/*");
 522                     // check if it realy is a block comment (and not //*)
 523                     if let Some(i) = block_open_index {
 524                         if i > 0 && &post_snippet[i - 1..i] == "/" {
 525                             block_open_index = None;
 526                         }
 527                     }
 528                     let newline_index = post_snippet.find('\n');
 529                     if let Some(separator_index) = post_snippet.find_uncommented(",") {
 530                         match (block_open_index, newline_index) {
 531                             // Separator before comment, with the next item on same line.
 532                             // Comment belongs to next item.
 533                             (Some(i), None) if i > separator_index => separator_index + 1,
 534                             // Block-style post-comment before the separator.
 535                             (Some(i), None) => cmp::max(
 536                                 find_comment_end(&post_snippet[i..]).unwrap() + i,
 537                                 separator_index + 1,
 538                             ),
 539                             // Block-style post-comment. Either before or after the separator.
 540                             (Some(i), Some(j)) if i < j => cmp::max(
 541                                 find_comment_end(&post_snippet[i..]).unwrap() + i,
 542                                 separator_index + 1,
 543                             ),
 544                             // Potential *single* line comment.
 545                             (_, Some(j)) if j > separator_index => j + 1,
 546                             _ => post_snippet.len(),
 547                         }
 548                     } else {
 549                         // Match arms may not have trailing comma. In any case, for match arms,
 550                         // we will assume that the post comment belongs to the next arm if they
 551                         // do not end with trailing comma.
 552                         1
 553                     }
 554                 }
 555                 None => post_snippet
 556                     .find_uncommented(self.terminator)
 557                     .unwrap_or(post_snippet.len()),
 558             };
 559
 560             if !post_snippet.is_empty() && comment_end > 0 {
 561                 // Account for extra whitespace between items. This is fiddly
 562                 // because of the way we divide pre- and post- comments.
 563
 564                 // Everything from the separator to the next item.
 565                 let test_snippet = &post_snippet[comment_end - 1..];
 566                 let first_newline = test_snippet.find('\n').unwrap_or(test_snippet.len());
 567                 // From the end of the first line of comments.
 568                 let test_snippet = &test_snippet[first_newline..];
 569                 let first = test_snippet
 570                     .find(|c: char| !c.is_whitespace())
 571                     .unwrap_or(test_snippet.len());
 572                 // From the end of the first line of comments to the next non-whitespace char.
 573                 let test_snippet = &test_snippet[..first];
 574
 575                 if test_snippet.chars().filter(|c| c == &'\n').count() > 1 {
 576                     // There were multiple line breaks which got trimmed to nothing.
 577                     new_lines = true;
 578                 }
 579             }
 580
 581             // Cleanup post-comment: strip separators and whitespace.
 582             self.prev_span_end = (self.get_hi)(&item) + BytePos(comment_end as u32);
 583             let post_snippet = post_snippet[..comment_end].trim();
 584
 585             let post_snippet_trimmed = if post_snippet.starts_with(',') {
 586                 post_snippet[1..].trim_matches(white_space)
 587             } else if post_snippet.ends_with(',') {
 588                 post_snippet[..(post_snippet.len() - 1)].trim_matches(white_space)
 589             } else {
 590                 post_snippet
 591             };
 592
 593             let post_comment = if !post_snippet_trimmed.is_empty() {
 594                 Some(post_snippet_trimmed.to_owned())
 595             } else {
 596                 None
 597             };
 598
 599             ListItem {
 600                 pre_comment: pre_comment,
 601                 pre_comment_style: pre_comment_style,
 602                 item: if self.inner.peek().is_none() && self.leave_last {
 603                     None
 604                 } else {
 605                     (self.get_item_string)(&item)
 606                 },
 607                 post_comment: post_comment,
 608                 new_lines: new_lines,
 609             }
 610         })
 611     }
 612 }
 613
 614 // Creates an iterator over a list's items with associated comments.
 615 pub fn itemize_list<'a, T, I, F1, F2, F3>(
 616     codemap: &'a CodeMap,
 617     inner: I,
 618     terminator: &'a str,
 619     get_lo: F1,
 620     get_hi: F2,
 621     get_item_string: F3,
 622     prev_span_end: BytePos,
 623     next_span_start: BytePos,
 624     leave_last: bool,
 625 ) -> ListItems<'a, I, F1, F2, F3>
 626 where
 627     I: Iterator<Item = T>,
 628     F1: Fn(&T) -> BytePos,
 629     F2: Fn(&T) -> BytePos,
 630     F3: Fn(&T) -> Option<String>,
 631 {
 632     ListItems {
 633         codemap: codemap,
 634         inner: inner.peekable(),
 635         get_lo: get_lo,
 636         get_hi: get_hi,
 637         get_item_string: get_item_string,
 638         prev_span_end: prev_span_end,
 639         next_span_start: next_span_start,
 640         terminator: terminator,
 641         leave_last: leave_last,
 642     }
 643 }
 644
 645 fn needs_trailing_separator(
 646     separator_tactic: SeparatorTactic,
 647     list_tactic: DefinitiveListTactic,
 648 ) -> bool {
 649     match separator_tactic {
 650         SeparatorTactic::Always => true,
 651         SeparatorTactic::Vertical => list_tactic == DefinitiveListTactic::Vertical,
 652         SeparatorTactic::Never => false,
 653     }
 654 }
 655
 656 /// Returns the count and total width of the list items.
 657 fn calculate_width<I, T>(items: I) -> (usize, usize)
 658 where
 659     I: IntoIterator<Item = T>,
 660     T: AsRef<ListItem>,
 661 {
 662     items
 663         .into_iter()
 664         .map(|item| total_item_width(item.as_ref()))
 665         .fold((0, 0), |acc, l| (acc.0 + 1, acc.1 + l))
 666 }
 667
 668 fn total_item_width(item: &ListItem) -> usize {
 669     comment_len(item.pre_comment.as_ref().map(|x| &(*x)[..])) +
 670         comment_len(item.post_comment.as_ref().map(|x| &(*x)[..])) +
 671         item.item.as_ref().map_or(0, |str| str.len())
 672 }
 673
 674 fn comment_len(comment: Option<&str>) -> usize {
 675     match comment {
 676         Some(s) => {
 677             let text_len = s.trim().len();
 678             if text_len > 0 {
 679                 // We'll put " /*" before and " */" after inline comments.
 680                 text_len + 6
 681             } else {
 682                 text_len
 683             }
 684         }
 685         None => 0,
 686     }
 687 }
 688
 689 // Compute horizontal and vertical shapes for a struct-lit-like thing.
 690 pub fn struct_lit_shape(
 691     shape: Shape,
 692     context: &RewriteContext,
 693     prefix_width: usize,
 694     suffix_width: usize,
 695 ) -> Option<(Option<Shape>, Shape)> {
 696     let v_shape = match context.config.struct_lit_style() {
 697         IndentStyle::Visual => try_opt!(
 698             try_opt!(shape.visual_indent(0).shrink_left(prefix_width)).sub_width(suffix_width)
 699         ),
 700         IndentStyle::Block => {
 701             let shape = shape.block_indent(context.config.tab_spaces());
 702             Shape {
 703                 width: try_opt!(context.config.max_width().checked_sub(shape.indent.width())),
 704                 ..shape
 705             }
 706         }
 707     };
 708     let shape_width = shape.width.checked_sub(prefix_width + suffix_width);
 709     if let Some(w) = shape_width {
 710         let shape_width = cmp::min(w, context.config.struct_lit_width());
 711         Some((Some(Shape::legacy(shape_width, shape.indent)), v_shape))
 712     } else {
 713         Some((None, v_shape))
 714     }
 715 }
 716
 717 // Compute the tactic for the internals of a struct-lit-like thing.
 718 pub fn struct_lit_tactic(
 719     h_shape: Option<Shape>,
 720     context: &RewriteContext,
 721     items: &[ListItem],
 722 ) -> DefinitiveListTactic {
 723     if let Some(h_shape) = h_shape {
 724         let prelim_tactic = match (context.config.struct_lit_style(), items.len()) {
 725             (IndentStyle::Visual, 1) => ListTactic::HorizontalVertical,
 726             _ => context.config.struct_lit_multiline_style().to_list_tactic(),
 727         };
 728         definitive_tactic(items, prelim_tactic, Separator::Comma, h_shape.width)
 729     } else {
 730         DefinitiveListTactic::Vertical
 731     }
 732 }
 733
 734 // Given a tactic and possible shapes for horizontal and vertical layout,
 735 // come up with the actual shape to use.
 736 pub fn shape_for_tactic(
 737     tactic: DefinitiveListTactic,
 738     h_shape: Option<Shape>,
 739     v_shape: Shape,
 740 ) -> Shape {
 741     match tactic {
 742         DefinitiveListTactic::Horizontal => h_shape.unwrap(),
 743         _ => v_shape,
 744     }
 745 }
 746
 747 // Create a ListFormatting object for formatting the internals of a
 748 // struct-lit-like thing, that is a series of fields.
 749 pub fn struct_lit_formatting<'a>(
 750     shape: Shape,
 751     tactic: DefinitiveListTactic,
 752     context: &'a RewriteContext,
 753     force_no_trailing_comma: bool,
 754 ) -> ListFormatting<'a> {
 755     let ends_with_newline = context.config.struct_lit_style() != IndentStyle::Visual &&
 756         tactic == DefinitiveListTactic::Vertical;
 757     ListFormatting {
 758         tactic: tactic,
 759         separator: ",",
 760         trailing_separator: if force_no_trailing_comma {
 761             SeparatorTactic::Never
 762         } else {
 763             context.config.trailing_comma()
 764         },
 765         shape: shape,
 766         ends_with_newline: ends_with_newline,
 767         preserve_newline: true,
 768         config: context.config,
 769     }
 770 }