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 /// Formatting tactic for lists. This will be cast down to a
  23 /// DefinitiveListTactic depending on the number and length of the items and
  24 /// their comments.
  25 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
  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 separator_place: SeparatorPlace,
  65     pub shape: Shape,
  66     // Non-expressions, e.g. items, will have a new line at the end of the list.
  67     // Important for comment styles.
  68     pub ends_with_newline: bool,
  69     // Remove newlines between list elements for expressions.
  70     pub preserve_newline: bool,
  71     pub config: &'a Config,
  72 }
  73
  74 impl<'a> ListFormatting<'a> {
  75     pub fn needs_trailing_separator(&self) -> bool {
  76         match self.trailing_separator {
  77             // We always put separator in front.
  78             SeparatorTactic::Always => true,
  79             SeparatorTactic::Vertical => self.tactic == DefinitiveListTactic::Vertical,
  80             SeparatorTactic::Never => {
  81                 self.tactic == DefinitiveListTactic::Vertical && self.separator_place.is_front()
  82             }
  83         }
  84     }
  85 }
  86
  87 impl AsRef<ListItem> for ListItem {
  88     fn as_ref(&self) -> &ListItem {
  89         self
  90     }
  91 }
  92
  93 #[derive(PartialEq, Eq)]
  94 pub enum ListItemCommentStyle {
  95     // Try to keep the comment on the same line with the item.
  96     SameLine,
  97     // Put the comment on the previous or the next line of the item.
  98     DifferentLine,
  99     // No comment available.
 100     None,
 101 }
 102
 103 pub struct ListItem {
 104     // None for comments mean that they are not present.
 105     pub pre_comment: Option<String>,
 106     pub pre_comment_style: ListItemCommentStyle,
 107     // Item should include attributes and doc comments. None indicates a failed
 108     // rewrite.
 109     pub item: Option<String>,
 110     pub post_comment: Option<String>,
 111     // Whether there is extra whitespace before this item.
 112     pub new_lines: bool,
 113 }
 114
 115 impl ListItem {
 116     pub fn inner_as_ref(&self) -> &str {
 117         self.item.as_ref().map_or("", |s| &*s)
 118     }
 119
 120     pub fn is_multiline(&self) -> bool {
 121         self.inner_as_ref().contains('\n') || self.pre_comment.is_some() ||
 122             self.post_comment
 123                 .as_ref()
 124                 .map_or(false, |s| s.contains('\n'))
 125     }
 126
 127     pub fn has_comment(&self) -> bool {
 128         self.pre_comment
 129             .as_ref()
 130             .map_or(false, |comment| comment.starts_with("//")) ||
 131             self.post_comment
 132                 .as_ref()
 133                 .map_or(false, |comment| comment.starts_with("//"))
 134     }
 135
 136     pub fn from_str<S: Into<String>>(s: S) -> ListItem {
 137         ListItem {
 138             pre_comment: None,
 139             pre_comment_style: ListItemCommentStyle::None,
 140             item: Some(s.into()),
 141             post_comment: None,
 142             new_lines: false,
 143         }
 144     }
 145 }
 146
 147 /// The definitive formatting tactic for lists.
 148 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
 149 pub enum DefinitiveListTactic {
 150     Vertical,
 151     Horizontal,
 152     Mixed,
 153 }
 154
 155 impl DefinitiveListTactic {
 156     pub fn ends_with_newline(&self, indent_style: IndentStyle) -> bool {
 157         match indent_style {
 158             IndentStyle::Block => *self != DefinitiveListTactic::Horizontal,
 159             IndentStyle::Visual => false,
 160         }
 161     }
 162 }
 163
 164 /// The type of separator for lists.
 165 #[derive(Eq, PartialEq, Debug)]
 166 pub enum Separator {
 167     Comma,
 168     VerticalBar,
 169 }
 170
 171 impl Separator {
 172     pub fn len(&self) -> usize {
 173         match *self {
 174             // 2 = `, `
 175             Separator::Comma => 2,
 176             // 3 = ` | `
 177             Separator::VerticalBar => 3,
 178         }
 179     }
 180 }
 181
 182 /// Where to put separator.
 183 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
 184 pub enum SeparatorPlace {
 185     Front,
 186     Back,
 187 }
 188
 189 impl_enum_serialize_and_deserialize!(SeparatorPlace, Front, Back);
 190
 191 impl SeparatorPlace {
 192     pub fn is_front(&self) -> bool {
 193         *self == SeparatorPlace::Front
 194     }
 195
 196     pub fn is_back(&self) -> bool {
 197         *self == SeparatorPlace::Back
 198     }
 199
 200     pub fn from_tactic(default: SeparatorPlace, tactic: DefinitiveListTactic) -> SeparatorPlace {
 201         match tactic {
 202             DefinitiveListTactic::Vertical => default,
 203             _ => SeparatorPlace::Back,
 204         }
 205     }
 206 }
 207
 208 pub fn definitive_tactic<I, T>(
 209     items: I,
 210     tactic: ListTactic,
 211     sep: Separator,
 212     width: usize,
 213 ) -> DefinitiveListTactic
 214 where
 215     I: IntoIterator<Item = T> + Clone,
 216     T: AsRef<ListItem>,
 217 {
 218     let pre_line_comments = items
 219         .clone()
 220         .into_iter()
 221         .any(|item| item.as_ref().has_comment());
 222
 223     let limit = match tactic {
 224         _ if pre_line_comments => return DefinitiveListTactic::Vertical,
 225         ListTactic::Mixed => return DefinitiveListTactic::Mixed,
 226         ListTactic::Horizontal => return DefinitiveListTactic::Horizontal,
 227         ListTactic::Vertical => return DefinitiveListTactic::Vertical,
 228         ListTactic::LimitedHorizontalVertical(limit) => ::std::cmp::min(width, limit),
 229         ListTactic::HorizontalVertical => width,
 230     };
 231
 232     let (sep_count, total_width) = calculate_width(items.clone());
 233     let total_sep_len = sep.len() * sep_count.checked_sub(1).unwrap_or(0);
 234     let real_total = total_width + total_sep_len;
 235
 236     if real_total <= limit && !pre_line_comments &&
 237         !items.into_iter().any(|item| item.as_ref().is_multiline())
 238     {
 239         DefinitiveListTactic::Horizontal
 240     } else {
 241         DefinitiveListTactic::Vertical
 242     }
 243 }
 244
 245 // Format a list of commented items into a string.
 246 // TODO: add unit tests
 247 pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
 248 where
 249     I: IntoIterator<Item = T> + Clone,
 250     T: AsRef<ListItem>,
 251 {
 252     let tactic = formatting.tactic;
 253     let sep_len = formatting.separator.len();
 254
 255     // Now that we know how we will layout, we can decide for sure if there
 256     // will be a trailing separator.
 257     let mut trailing_separator = formatting.needs_trailing_separator();
 258     let mut result = String::new();
 259     let cloned_items = items.clone();
 260     let mut iter = items.into_iter().enumerate().peekable();
 261     let mut item_max_width: Option<usize> = None;
 262     let mut sep_place = SeparatorPlace::from_tactic(formatting.separator_place, tactic);
 263
 264     let mut line_len = 0;
 265     let indent_str = &formatting.shape.indent.to_string(formatting.config);
 266     while let Some((i, item)) = iter.next() {
 267         let item = item.as_ref();
 268         let inner_item = try_opt!(item.item.as_ref());
 269         let first = i == 0;
 270         let last = iter.peek().is_none();
 271         let mut separate = !last || trailing_separator;
 272         let item_sep_len = if separate { sep_len } else { 0 };
 273
 274         // Item string may be multi-line. Its length (used for block comment alignment)
 275         // should be only the length of the last line.
 276         let item_last_line = if item.is_multiline() {
 277             inner_item.lines().last().unwrap_or("")
 278         } else {
 279             inner_item.as_ref()
 280         };
 281         let mut item_last_line_width = item_last_line.len() + item_sep_len;
 282         if item_last_line.starts_with(indent_str) {
 283             item_last_line_width -= indent_str.len();
 284         }
 285
 286         match tactic {
 287             DefinitiveListTactic::Horizontal if !first => {
 288                 result.push(' ');
 289             }
 290             DefinitiveListTactic::Vertical if !first => {
 291                 result.push('\n');
 292                 result.push_str(indent_str);
 293             }
 294             DefinitiveListTactic::Mixed => {
 295                 let total_width = total_item_width(item) + item_sep_len;
 296
 297                 // 1 is space between separator and item.
 298                 if line_len > 0 && line_len + 1 + total_width > formatting.shape.width {
 299                     result.push('\n');
 300                     result.push_str(indent_str);
 301                     line_len = 0;
 302                     if formatting.ends_with_newline {
 303                         if last {
 304                             separate = true;
 305                         } else {
 306                             trailing_separator = true;
 307                         }
 308                     }
 309                     sep_place = formatting.separator_place;
 310                 } else {
 311                     sep_place = SeparatorPlace::Back;
 312                 }
 313
 314                 if line_len > 0 {
 315                     result.push(' ');
 316                     line_len += 1;
 317                 }
 318
 319                 line_len += total_width;
 320             }
 321             _ => {}
 322         }
 323
 324         // Pre-comments
 325         if let Some(ref comment) = item.pre_comment {
 326             // Block style in non-vertical mode.
 327             let block_mode = tactic != DefinitiveListTactic::Vertical;
 328             // Width restriction is only relevant in vertical mode.
 329             let comment = try_opt!(rewrite_comment(
 330                 comment,
 331                 block_mode,
 332                 formatting.shape,
 333                 formatting.config,
 334             ));
 335             result.push_str(&comment);
 336
 337             if tactic == DefinitiveListTactic::Vertical {
 338                 // We cannot keep pre-comments on the same line if the comment if normalized.
 339                 let keep_comment = if formatting.config.normalize_comments() {
 340                     false
 341                 } else if item.pre_comment_style == ListItemCommentStyle::DifferentLine {
 342                     false
 343                 } else {
 344                     // We will try to keep the comment on the same line with the item here.
 345                     // 1 = ` `
 346                     let total_width = total_item_width(item) + item_sep_len + 1;
 347                     total_width <= formatting.shape.width
 348                 };
 349                 if keep_comment {
 350                     result.push(' ');
 351                 } else {
 352                     result.push('\n');
 353                     result.push_str(indent_str);
 354                 }
 355             } else {
 356                 result.push(' ');
 357             }
 358             item_max_width = None;
 359         }
 360
 361         if separate && sep_place.is_front() && !first {
 362             result.push_str(formatting.separator.trim());
 363             result.push(' ');
 364         }
 365         result.push_str(&inner_item[..]);
 366
 367         // Post-comments
 368         if tactic != DefinitiveListTactic::Vertical && item.post_comment.is_some() {
 369             let comment = item.post_comment.as_ref().unwrap();
 370             let formatted_comment = try_opt!(rewrite_comment(
 371                 comment,
 372                 true,
 373                 Shape::legacy(formatting.shape.width, Indent::empty()),
 374                 formatting.config,
 375             ));
 376
 377             result.push(' ');
 378             result.push_str(&formatted_comment);
 379         }
 380
 381         if separate && sep_place.is_back() {
 382             result.push_str(formatting.separator);
 383         }
 384
 385         if tactic == DefinitiveListTactic::Vertical && item.post_comment.is_some() {
 386             let comment = item.post_comment.as_ref().unwrap();
 387             let overhead = last_line_width(&result) + first_line_width(comment.trim());
 388
 389             let rewrite_post_comment = |item_max_width: &mut Option<usize>| {
 390                 if item_max_width.is_none() && !last && !inner_item.contains('\n') {
 391                     *item_max_width = Some(max_width_of_item_with_post_comment(
 392                         &cloned_items,
 393                         i,
 394                         overhead,
 395                         formatting.config.max_width(),
 396                     ));
 397                 }
 398                 let overhead = if let &mut Some(max_width) = item_max_width {
 399                     max_width + 2
 400                 } else {
 401                     // 1 = space between item and comment.
 402                     item_last_line_width + 1
 403                 };
 404                 let width = formatting.shape.width.checked_sub(overhead).unwrap_or(1);
 405                 let offset = formatting.shape.indent + overhead;
 406                 let comment_shape = Shape::legacy(width, offset);
 407
 408                 // Use block-style only for the last item or multiline comments.
 409                 let block_style = !formatting.ends_with_newline && last ||
 410                     comment.trim().contains('\n') ||
 411                     comment.trim().len() > width;
 412
 413                 rewrite_comment(comment, block_style, comment_shape, formatting.config)
 414             };
 415
 416             let mut formatted_comment = try_opt!(rewrite_post_comment(&mut item_max_width));
 417
 418             if !formatted_comment.starts_with('\n') {
 419                 let mut comment_alignment =
 420                     post_comment_alignment(item_max_width, inner_item.len());
 421                 if first_line_width(&formatted_comment) + last_line_width(&result) +
 422                     comment_alignment + 1 > formatting.config.max_width()
 423                 {
 424                     item_max_width = None;
 425                     formatted_comment = try_opt!(rewrite_post_comment(&mut item_max_width));
 426                     comment_alignment = post_comment_alignment(item_max_width, inner_item.len());
 427                 }
 428                 for _ in 0..(comment_alignment + 1) {
 429                     result.push(' ');
 430                 }
 431                 // An additional space for the missing trailing separator.
 432                 if last && item_max_width.is_some() && !separate && !formatting.separator.is_empty()
 433                 {
 434                     result.push(' ');
 435                 }
 436             }
 437             if formatted_comment.contains('\n') {
 438                 item_max_width = None;
 439             }
 440             result.push_str(&formatted_comment);
 441         } else {
 442             item_max_width = None;
 443         }
 444
 445         if formatting.preserve_newline && !last && tactic == DefinitiveListTactic::Vertical &&
 446             item.new_lines
 447         {
 448             item_max_width = None;
 449             result.push('\n');
 450         }
 451     }
 452
 453     Some(result)
 454 }
 455
 456 fn max_width_of_item_with_post_comment<I, T>(
 457     items: &I,
 458     i: usize,
 459     overhead: usize,
 460     max_budget: usize,
 461 ) -> usize
 462 where
 463     I: IntoIterator<Item = T> + Clone,
 464     T: AsRef<ListItem>,
 465 {
 466     let mut max_width = 0;
 467     let mut first = true;
 468     for item in items.clone().into_iter().skip(i) {
 469         let item = item.as_ref();
 470         let inner_item_width = item.inner_as_ref().len();
 471         if !first &&
 472             (item.is_multiline() || !item.post_comment.is_some() ||
 473                 inner_item_width + overhead > max_budget)
 474         {
 475             return max_width;
 476         }
 477         if max_width < inner_item_width {
 478             max_width = inner_item_width;
 479         }
 480         if item.new_lines {
 481             return max_width;
 482         }
 483         first = false;
 484     }
 485     max_width
 486 }
 487
 488 fn post_comment_alignment(item_max_width: Option<usize>, inner_item_len: usize) -> usize {
 489     item_max_width
 490         .and_then(|max_line_width| max_line_width.checked_sub(inner_item_len))
 491         .unwrap_or(0)
 492 }
 493
 494 pub struct ListItems<'a, I, F1, F2, F3>
 495 where
 496     I: Iterator,
 497 {
 498     codemap: &'a CodeMap,
 499     inner: Peekable<I>,
 500     get_lo: F1,
 501     get_hi: F2,
 502     get_item_string: F3,
 503     prev_span_end: BytePos,
 504     next_span_start: BytePos,
 505     terminator: &'a str,
 506     leave_last: bool,
 507 }
 508
 509 impl<'a, T, I, F1, F2, F3> Iterator for ListItems<'a, I, F1, F2, F3>
 510 where
 511     I: Iterator<Item = T>,
 512     F1: Fn(&T) -> BytePos,
 513     F2: Fn(&T) -> BytePos,
 514     F3: Fn(&T) -> Option<String>,
 515 {
 516     type Item = ListItem;
 517
 518     fn next(&mut self) -> Option<Self::Item> {
 519         let white_space: &[_] = &[' ', '\t'];
 520
 521         self.inner.next().map(|item| {
 522             let mut new_lines = false;
 523             // Pre-comment
 524             let pre_snippet = self.codemap
 525                 .span_to_snippet(mk_sp(self.prev_span_end, (self.get_lo)(&item)))
 526                 .unwrap();
 527             let trimmed_pre_snippet = pre_snippet.trim();
 528             let has_single_line_comment = trimmed_pre_snippet.starts_with("//");
 529             let has_block_comment = trimmed_pre_snippet.starts_with("/*");
 530             let (pre_comment, pre_comment_style) = if has_single_line_comment {
 531                 (
 532                     Some(trimmed_pre_snippet.to_owned()),
 533                     ListItemCommentStyle::DifferentLine,
 534                 )
 535             } else if has_block_comment {
 536                 let comment_end = pre_snippet.chars().rev().position(|c| c == '/').unwrap();
 537                 if pre_snippet
 538                     .chars()
 539                     .rev()
 540                     .take(comment_end + 1)
 541                     .find(|c| *c == '\n')
 542                     .is_some()
 543                 {
 544                     (
 545                         Some(trimmed_pre_snippet.to_owned()),
 546                         ListItemCommentStyle::DifferentLine,
 547                     )
 548                 } else {
 549                     (
 550                         Some(trimmed_pre_snippet.to_owned()),
 551                         ListItemCommentStyle::SameLine,
 552                     )
 553                 }
 554             } else {
 555                 (None, ListItemCommentStyle::None)
 556             };
 557
 558             // Post-comment
 559             let next_start = match self.inner.peek() {
 560                 Some(next_item) => (self.get_lo)(next_item),
 561                 None => self.next_span_start,
 562             };
 563             let post_snippet = self.codemap
 564                 .span_to_snippet(mk_sp((self.get_hi)(&item), next_start))
 565                 .unwrap();
 566
 567             let comment_end = match self.inner.peek() {
 568                 Some(..) => {
 569                     let mut block_open_index = post_snippet.find("/*");
 570                     // check if it realy is a block comment (and not //*)
 571                     if let Some(i) = block_open_index {
 572                         if i > 0 && &post_snippet[i - 1..i] == "/" {
 573                             block_open_index = None;
 574                         }
 575                     }
 576                     let newline_index = post_snippet.find('\n');
 577                     if let Some(separator_index) = post_snippet.find_uncommented(",") {
 578                         match (block_open_index, newline_index) {
 579                             // Separator before comment, with the next item on same line.
 580                             // Comment belongs to next item.
 581                             (Some(i), None) if i > separator_index => separator_index + 1,
 582                             // Block-style post-comment before the separator.
 583                             (Some(i), None) => cmp::max(
 584                                 find_comment_end(&post_snippet[i..]).unwrap() + i,
 585                                 separator_index + 1,
 586                             ),
 587                             // Block-style post-comment. Either before or after the separator.
 588                             (Some(i), Some(j)) if i < j => cmp::max(
 589                                 find_comment_end(&post_snippet[i..]).unwrap() + i,
 590                                 separator_index + 1,
 591                             ),
 592                             // Potential *single* line comment.
 593                             (_, Some(j)) if j > separator_index => j + 1,
 594                             _ => post_snippet.len(),
 595                         }
 596                     } else {
 597                         // Match arms may not have trailing comma. In any case, for match arms,
 598                         // we will assume that the post comment belongs to the next arm if they
 599                         // do not end with trailing comma.
 600                         1
 601                     }
 602                 }
 603                 None => post_snippet
 604                     .find_uncommented(self.terminator)
 605                     .unwrap_or(post_snippet.len()),
 606             };
 607
 608             if !post_snippet.is_empty() && comment_end > 0 {
 609                 // Account for extra whitespace between items. This is fiddly
 610                 // because of the way we divide pre- and post- comments.
 611
 612                 // Everything from the separator to the next item.
 613                 let test_snippet = &post_snippet[comment_end - 1..];
 614                 let first_newline = test_snippet.find('\n').unwrap_or(test_snippet.len());
 615                 // From the end of the first line of comments.
 616                 let test_snippet = &test_snippet[first_newline..];
 617                 let first = test_snippet
 618                     .find(|c: char| !c.is_whitespace())
 619                     .unwrap_or(test_snippet.len());
 620                 // From the end of the first line of comments to the next non-whitespace char.
 621                 let test_snippet = &test_snippet[..first];
 622
 623                 if test_snippet.chars().filter(|c| c == &'\n').count() > 1 {
 624                     // There were multiple line breaks which got trimmed to nothing.
 625                     new_lines = true;
 626                 }
 627             }
 628
 629             // Cleanup post-comment: strip separators and whitespace.
 630             self.prev_span_end = (self.get_hi)(&item) + BytePos(comment_end as u32);
 631             let post_snippet = post_snippet[..comment_end].trim();
 632
 633             let post_snippet_trimmed = if post_snippet.starts_with(',') {
 634                 post_snippet[1..].trim_matches(white_space)
 635             } else if post_snippet.ends_with(',') {
 636                 post_snippet[..(post_snippet.len() - 1)].trim_matches(white_space)
 637             } else {
 638                 post_snippet
 639             };
 640
 641             let post_comment = if !post_snippet_trimmed.is_empty() {
 642                 Some(post_snippet_trimmed.to_owned())
 643             } else {
 644                 None
 645             };
 646
 647             ListItem {
 648                 pre_comment: pre_comment,
 649                 pre_comment_style: pre_comment_style,
 650                 item: if self.inner.peek().is_none() && self.leave_last {
 651                     None
 652                 } else {
 653                     (self.get_item_string)(&item)
 654                 },
 655                 post_comment: post_comment,
 656                 new_lines: new_lines,
 657             }
 658         })
 659     }
 660 }
 661
 662 // Creates an iterator over a list's items with associated comments.
 663 pub fn itemize_list<'a, T, I, F1, F2, F3>(
 664     codemap: &'a CodeMap,
 665     inner: I,
 666     terminator: &'a str,
 667     get_lo: F1,
 668     get_hi: F2,
 669     get_item_string: F3,
 670     prev_span_end: BytePos,
 671     next_span_start: BytePos,
 672     leave_last: bool,
 673 ) -> ListItems<'a, I, F1, F2, F3>
 674 where
 675     I: Iterator<Item = T>,
 676     F1: Fn(&T) -> BytePos,
 677     F2: Fn(&T) -> BytePos,
 678     F3: Fn(&T) -> Option<String>,
 679 {
 680     ListItems {
 681         codemap: codemap,
 682         inner: inner.peekable(),
 683         get_lo: get_lo,
 684         get_hi: get_hi,
 685         get_item_string: get_item_string,
 686         prev_span_end: prev_span_end,
 687         next_span_start: next_span_start,
 688         terminator: terminator,
 689         leave_last: leave_last,
 690     }
 691 }
 692
 693 /// Returns the count and total width of the list items.
 694 fn calculate_width<I, T>(items: I) -> (usize, usize)
 695 where
 696     I: IntoIterator<Item = T>,
 697     T: AsRef<ListItem>,
 698 {
 699     items
 700         .into_iter()
 701         .map(|item| total_item_width(item.as_ref()))
 702         .fold((0, 0), |acc, l| (acc.0 + 1, acc.1 + l))
 703 }
 704
 705 fn total_item_width(item: &ListItem) -> usize {
 706     comment_len(item.pre_comment.as_ref().map(|x| &(*x)[..])) +
 707         comment_len(item.post_comment.as_ref().map(|x| &(*x)[..])) +
 708         item.item.as_ref().map_or(0, |str| str.len())
 709 }
 710
 711 fn comment_len(comment: Option<&str>) -> usize {
 712     match comment {
 713         Some(s) => {
 714             let text_len = s.trim().len();
 715             if text_len > 0 {
 716                 // We'll put " /*" before and " */" after inline comments.
 717                 text_len + 6
 718             } else {
 719                 text_len
 720             }
 721         }
 722         None => 0,
 723     }
 724 }
 725
 726 // Compute horizontal and vertical shapes for a struct-lit-like thing.
 727 pub fn struct_lit_shape(
 728     shape: Shape,
 729     context: &RewriteContext,
 730     prefix_width: usize,
 731     suffix_width: usize,
 732 ) -> Option<(Option<Shape>, Shape)> {
 733     let v_shape = match context.config.struct_lit_style() {
 734         IndentStyle::Visual => try_opt!(
 735             try_opt!(shape.visual_indent(0).shrink_left(prefix_width)).sub_width(suffix_width)
 736         ),
 737         IndentStyle::Block => {
 738             let shape = shape.block_indent(context.config.tab_spaces());
 739             Shape {
 740                 width: try_opt!(context.config.max_width().checked_sub(shape.indent.width())),
 741                 ..shape
 742             }
 743         }
 744     };
 745     let shape_width = shape.width.checked_sub(prefix_width + suffix_width);
 746     if let Some(w) = shape_width {
 747         let shape_width = cmp::min(w, context.config.struct_lit_width());
 748         Some((Some(Shape::legacy(shape_width, shape.indent)), v_shape))
 749     } else {
 750         Some((None, v_shape))
 751     }
 752 }
 753
 754 // Compute the tactic for the internals of a struct-lit-like thing.
 755 pub fn struct_lit_tactic(
 756     h_shape: Option<Shape>,
 757     context: &RewriteContext,
 758     items: &[ListItem],
 759 ) -> DefinitiveListTactic {
 760     if let Some(h_shape) = h_shape {
 761         let prelim_tactic = match (context.config.struct_lit_style(), items.len()) {
 762             (IndentStyle::Visual, 1) => ListTactic::HorizontalVertical,
 763             _ => context.config.struct_lit_multiline_style().to_list_tactic(),
 764         };
 765         definitive_tactic(items, prelim_tactic, Separator::Comma, h_shape.width)
 766     } else {
 767         DefinitiveListTactic::Vertical
 768     }
 769 }
 770
 771 // Given a tactic and possible shapes for horizontal and vertical layout,
 772 // come up with the actual shape to use.
 773 pub fn shape_for_tactic(
 774     tactic: DefinitiveListTactic,
 775     h_shape: Option<Shape>,
 776     v_shape: Shape,
 777 ) -> Shape {
 778     match tactic {
 779         DefinitiveListTactic::Horizontal => h_shape.unwrap(),
 780         _ => v_shape,
 781     }
 782 }
 783
 784 // Create a ListFormatting object for formatting the internals of a
 785 // struct-lit-like thing, that is a series of fields.
 786 pub fn struct_lit_formatting<'a>(
 787     shape: Shape,
 788     tactic: DefinitiveListTactic,
 789     context: &'a RewriteContext,
 790     force_no_trailing_comma: bool,
 791 ) -> ListFormatting<'a> {
 792     let ends_with_newline = context.config.struct_lit_style() != IndentStyle::Visual &&
 793         tactic == DefinitiveListTactic::Vertical;
 794     ListFormatting {
 795         tactic: tactic,
 796         separator: ",",
 797         trailing_separator: if force_no_trailing_comma {
 798             SeparatorTactic::Never
 799         } else {
 800             context.config.trailing_comma()
 801         },
 802         separator_place: SeparatorPlace::Back,
 803         shape: shape,
 804         ends_with_newline: ends_with_newline,
 805         preserve_newline: true,
 806         config: context.config,
 807     }
 808 }