src/tools/rustfmt/src/missed_spans.rs

   1 use rustc_span::{BytePos, Pos, Span};
   2
   3 use crate::comment::{is_last_comment_block, rewrite_comment, CodeCharKind, CommentCodeSlices};
   4 use crate::config::file_lines::FileLines;
   5 use crate::config::FileName;
   6 use crate::config::Version;
   7 use crate::coverage::transform_missing_snippet;
   8 use crate::shape::{Indent, Shape};
   9 use crate::source_map::LineRangeUtils;
  10 use crate::utils::{count_lf_crlf, count_newlines, last_line_width, mk_sp};
  11 use crate::visitor::FmtVisitor;
  12
  13 struct SnippetStatus {
  14     /// An offset to the current line from the beginning of the original snippet.
  15     line_start: usize,
  16     /// A length of trailing whitespaces on the current line.
  17     last_wspace: Option<usize>,
  18     /// The current line number.
  19     cur_line: usize,
  20 }
  21
  22 impl SnippetStatus {
  23     fn new(cur_line: usize) -> Self {
  24         SnippetStatus {
  25             line_start: 0,
  26             last_wspace: None,
  27             cur_line,
  28         }
  29     }
  30 }
  31
  32 impl<'a> FmtVisitor<'a> {
  33     fn output_at_start(&self) -> bool {
  34         self.buffer.is_empty()
  35     }
  36
  37     pub(crate) fn format_missing(&mut self, end: BytePos) {
  38         // HACK(topecongiro): we use `format_missing()` to extract a missing comment between
  39         // a macro (or similar) and a trailing semicolon. Here we just try to avoid calling
  40         // `format_missing_inner` in the common case where there is no such comment.
  41         // This is a hack, ideally we should fix a possible bug in `format_missing_inner`
  42         // or refactor `visit_mac` and `rewrite_macro`, but this should suffice to fix the
  43         // issue (#2727).
  44         let missing_snippet = self.snippet(mk_sp(self.last_pos, end));
  45         if missing_snippet.trim() == ";" {
  46             self.push_str(";");
  47             self.last_pos = end;
  48             return;
  49         }
  50         self.format_missing_inner(end, |this, last_snippet, _| this.push_str(last_snippet))
  51     }
  52
  53     pub(crate) fn format_missing_with_indent(&mut self, end: BytePos) {
  54         let config = self.config;
  55         self.format_missing_inner(end, |this, last_snippet, snippet| {
  56             this.push_str(last_snippet.trim_end());
  57             if last_snippet == snippet && !this.output_at_start() {
  58                 // No new lines in the snippet.
  59                 this.push_str("\n");
  60             }
  61             let indent = this.block_indent.to_string(config);
  62             this.push_str(&indent);
  63         })
  64     }
  65
  66     pub(crate) fn format_missing_no_indent(&mut self, end: BytePos) {
  67         self.format_missing_inner(end, |this, last_snippet, _| {
  68             this.push_str(last_snippet.trim_end());
  69         })
  70     }
  71
  72     fn format_missing_inner<F: Fn(&mut FmtVisitor<'_>, &str, &str)>(
  73         &mut self,
  74         end: BytePos,
  75         process_last_snippet: F,
  76     ) {
  77         let start = self.last_pos;
  78
  79         if start == end {
  80             // Do nothing if this is the beginning of the file.
  81             if !self.output_at_start() {
  82                 process_last_snippet(self, "", "");
  83             }
  84             return;
  85         }
  86
  87         assert!(
  88             start < end,
  89             "Request to format inverted span: {}",
  90             self.parse_sess.span_to_debug_info(mk_sp(start, end)),
  91         );
  92
  93         self.last_pos = end;
  94         let span = mk_sp(start, end);
  95         let snippet = self.snippet(span);
  96
  97         // Do nothing for spaces in the beginning of the file
  98         if start == BytePos(0) && end.0 as usize == snippet.len() && snippet.trim().is_empty() {
  99             return;
 100         }
 101
 102         if snippet.trim().is_empty() && !out_of_file_lines_range!(self, span) {
 103             // Keep vertical spaces within range.
 104             self.push_vertical_spaces(count_newlines(snippet));
 105             process_last_snippet(self, "", snippet);
 106         } else {
 107             self.write_snippet(span, &process_last_snippet);
 108         }
 109     }
 110
 111     fn push_vertical_spaces(&mut self, mut newline_count: usize) {
 112         let offset = self.buffer.chars().rev().take_while(|c| *c == '\n').count();
 113         let newline_upper_bound = self.config.blank_lines_upper_bound() + 1;
 114         let newline_lower_bound = self.config.blank_lines_lower_bound() + 1;
 115
 116         if newline_count + offset > newline_upper_bound {
 117             if offset >= newline_upper_bound {
 118                 newline_count = 0;
 119             } else {
 120                 newline_count = newline_upper_bound - offset;
 121             }
 122         } else if newline_count + offset < newline_lower_bound {
 123             if offset >= newline_lower_bound {
 124                 newline_count = 0;
 125             } else {
 126                 newline_count = newline_lower_bound - offset;
 127             }
 128         }
 129
 130         let blank_lines = "\n".repeat(newline_count);
 131         self.push_str(&blank_lines);
 132     }
 133
 134     fn write_snippet<F>(&mut self, span: Span, process_last_snippet: F)
 135     where
 136         F: Fn(&mut FmtVisitor<'_>, &str, &str),
 137     {
 138         // Get a snippet from the file start to the span's hi without allocating.
 139         // We need it to determine what precedes the current comment. If the comment
 140         // follows code on the same line, we won't touch it.
 141         let big_span_lo = self.snippet_provider.start_pos();
 142         let big_snippet = self.snippet_provider.entire_snippet();
 143         let big_diff = (span.lo() - big_span_lo).to_usize();
 144
 145         let snippet = self.snippet(span);
 146
 147         debug!("write_snippet `{}`", snippet);
 148
 149         self.write_snippet_inner(big_snippet, snippet, big_diff, span, process_last_snippet);
 150     }
 151
 152     fn write_snippet_inner<F>(
 153         &mut self,
 154         big_snippet: &str,
 155         old_snippet: &str,
 156         big_diff: usize,
 157         span: Span,
 158         process_last_snippet: F,
 159     ) where
 160         F: Fn(&mut FmtVisitor<'_>, &str, &str),
 161     {
 162         // Trim whitespace from the right hand side of each line.
 163         // Annoyingly, the library functions for splitting by lines etc. are not
 164         // quite right, so we must do it ourselves.
 165         let line = self.parse_sess.line_of_byte_pos(span.lo());
 166         let file_name = &self.parse_sess.span_to_filename(span);
 167         let mut status = SnippetStatus::new(line);
 168
 169         let snippet = &*transform_missing_snippet(self.config, old_snippet);
 170
 171         let slice_within_file_lines_range =
 172             |file_lines: FileLines, cur_line, s| -> (usize, usize, bool) {
 173                 let (lf_count, crlf_count) = count_lf_crlf(s);
 174                 let newline_count = lf_count + crlf_count;
 175                 let within_file_lines_range = file_lines.contains_range(
 176                     file_name,
 177                     cur_line,
 178                     // if a newline character is at the end of the slice, then the number of
 179                     // newlines needs to be decreased by 1 so that the range checked against
 180                     // the file_lines is the visual range one would expect.
 181                     cur_line + newline_count - if s.ends_with('\n') { 1 } else { 0 },
 182                 );
 183                 (lf_count, crlf_count, within_file_lines_range)
 184             };
 185         for (kind, offset, subslice) in CommentCodeSlices::new(snippet) {
 186             debug!("{:?}: {:?}", kind, subslice);
 187
 188             let (lf_count, crlf_count, within_file_lines_range) =
 189                 slice_within_file_lines_range(self.config.file_lines(), status.cur_line, subslice);
 190             let newline_count = lf_count + crlf_count;
 191             if CodeCharKind::Comment == kind && within_file_lines_range {
 192                 // 1: comment.
 193                 self.process_comment(
 194                     &mut status,
 195                     snippet,
 196                     &big_snippet[..(offset + big_diff)],
 197                     offset,
 198                     subslice,
 199                 );
 200             } else if subslice.trim().is_empty() && newline_count > 0 && within_file_lines_range {
 201                 // 2: blank lines.
 202                 self.push_vertical_spaces(newline_count);
 203                 status.cur_line += newline_count;
 204                 status.line_start = offset + lf_count + crlf_count * 2;
 205             } else {
 206                 // 3: code which we failed to format or which is not within file-lines range.
 207                 self.process_missing_code(&mut status, snippet, subslice, offset, file_name);
 208             }
 209         }
 210
 211         let last_snippet = &snippet[status.line_start..];
 212         let (_, _, within_file_lines_range) =
 213             slice_within_file_lines_range(self.config.file_lines(), status.cur_line, last_snippet);
 214         if within_file_lines_range {
 215             process_last_snippet(self, last_snippet, snippet);
 216         } else {
 217             // just append what's left
 218             self.push_str(last_snippet);
 219         }
 220     }
 221
 222     fn process_comment(
 223         &mut self,
 224         status: &mut SnippetStatus,
 225         snippet: &str,
 226         big_snippet: &str,
 227         offset: usize,
 228         subslice: &str,
 229     ) {
 230         let last_char = big_snippet
 231             .chars()
 232             .rev()
 233             .find(|rev_c| ![' ', '\t'].contains(rev_c));
 234
 235         let fix_indent = last_char.map_or(true, |rev_c| ['{', '\n'].contains(&rev_c));
 236         let mut on_same_line = false;
 237
 238         let comment_indent = if fix_indent {
 239             if let Some('{') = last_char {
 240                 self.push_str("\n");
 241             }
 242             let indent_str = self.block_indent.to_string(self.config);
 243             self.push_str(&indent_str);
 244             self.block_indent
 245         } else if self.config.version() == Version::Two && !snippet.starts_with('\n') {
 246             // The comment appears on the same line as the previous formatted code.
 247             // Assuming that comment is logically associated with that code, we want to keep it on
 248             // the same level and avoid mixing it with possible other comment.
 249             on_same_line = true;
 250             self.push_str(" ");
 251             self.block_indent
 252         } else {
 253             self.push_str(" ");
 254             Indent::from_width(self.config, last_line_width(&self.buffer))
 255         };
 256
 257         let comment_width = ::std::cmp::min(
 258             self.config.comment_width(),
 259             self.config.max_width() - self.block_indent.width(),
 260         );
 261         let comment_shape = Shape::legacy(comment_width, comment_indent);
 262
 263         if on_same_line {
 264             match subslice.find('\n') {
 265                 None => {
 266                     self.push_str(subslice);
 267                 }
 268                 Some(offset) if offset + 1 == subslice.len() => {
 269                     self.push_str(&subslice[..offset]);
 270                 }
 271                 Some(offset) => {
 272                     // keep first line as is: if it were too long and wrapped, it may get mixed
 273                     // with the other lines.
 274                     let first_line = &subslice[..offset];
 275                     self.push_str(first_line);
 276                     self.push_str(&comment_indent.to_string_with_newline(self.config));
 277
 278                     let other_lines = &subslice[offset + 1..];
 279                     let comment_str =
 280                         rewrite_comment(other_lines, false, comment_shape, self.config)
 281                             .unwrap_or_else(|| String::from(other_lines));
 282                     self.push_str(&comment_str);
 283                 }
 284             }
 285         } else {
 286             let comment_str = rewrite_comment(subslice, false, comment_shape, self.config)
 287                 .unwrap_or_else(|| String::from(subslice));
 288             self.push_str(&comment_str);
 289         }
 290
 291         status.last_wspace = None;
 292         status.line_start = offset + subslice.len();
 293
 294         // Add a newline:
 295         // - if there isn't one already
 296         // - otherwise, only if the last line is a line comment
 297         if status.line_start <= snippet.len() {
 298             match snippet[status.line_start..]
 299                 .chars()
 300                 // skip trailing whitespaces
 301                 .find(|c| !(*c == ' ' || *c == '\t'))
 302             {
 303                 Some('\n') | Some('\r') => {
 304                     if !is_last_comment_block(subslice) {
 305                         self.push_str("\n");
 306                     }
 307                 }
 308                 _ => self.push_str("\n"),
 309             }
 310         }
 311
 312         status.cur_line += count_newlines(subslice);
 313     }
 314
 315     fn process_missing_code(
 316         &mut self,
 317         status: &mut SnippetStatus,
 318         snippet: &str,
 319         subslice: &str,
 320         offset: usize,
 321         file_name: &FileName,
 322     ) {
 323         for (mut i, c) in subslice.char_indices() {
 324             i += offset;
 325
 326             if c == '\n' {
 327                 let skip_this_line = !self
 328                     .config
 329                     .file_lines()
 330                     .contains_line(file_name, status.cur_line);
 331                 if skip_this_line {
 332                     status.last_wspace = None;
 333                 }
 334
 335                 if let Some(lw) = status.last_wspace {
 336                     self.push_str(&snippet[status.line_start..lw]);
 337                     self.push_str("\n");
 338                     status.last_wspace = None;
 339                 } else {
 340                     self.push_str(&snippet[status.line_start..=i]);
 341                 }
 342
 343                 status.cur_line += 1;
 344                 status.line_start = i + 1;
 345             } else if c.is_whitespace() && status.last_wspace.is_none() {
 346                 status.last_wspace = Some(i);
 347             } else {
 348                 status.last_wspace = None;
 349             }
 350         }
 351
 352         let remaining = snippet[status.line_start..subslice.len() + offset].trim();
 353         if !remaining.is_empty() {
 354             self.push_str(&self.block_indent.to_string(self.config));
 355             self.push_str(remaining);
 356             status.line_start = subslice.len() + offset;
 357         }
 358     }
 359 }