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         self.format_missing_indent(end, true)
  55     }
  56
  57     pub(crate) fn format_missing_no_indent(&mut self, end: BytePos) {
  58         self.format_missing_indent(end, false)
  59     }
  60
  61     fn format_missing_indent(&mut self, end: BytePos, should_indent: bool) {
  62         let config = self.config;
  63         self.format_missing_inner(end, |this, last_snippet, snippet| {
  64             this.push_str(last_snippet.trim_end());
  65             if last_snippet == snippet && !this.output_at_start() {
  66                 // No new lines in the snippet.
  67                 this.push_str("\n");
  68             }
  69             if should_indent {
  70                 let indent = this.block_indent.to_string(config);
  71                 this.push_str(&indent);
  72             }
  73         })
  74     }
  75
  76     fn format_missing_inner<F: Fn(&mut FmtVisitor<'_>, &str, &str)>(
  77         &mut self,
  78         end: BytePos,
  79         process_last_snippet: F,
  80     ) {
  81         let start = self.last_pos;
  82
  83         if start == end {
  84             // Do nothing if this is the beginning of the file.
  85             if !self.output_at_start() {
  86                 process_last_snippet(self, "", "");
  87             }
  88             return;
  89         }
  90
  91         assert!(
  92             start < end,
  93             "Request to format inverted span: {}",
  94             self.parse_sess.span_to_debug_info(mk_sp(start, end)),
  95         );
  96
  97         self.last_pos = end;
  98         let span = mk_sp(start, end);
  99         let snippet = self.snippet(span);
 100
 101         // Do nothing for spaces in the beginning of the file
 102         if start == BytePos(0) && end.0 as usize == snippet.len() && snippet.trim().is_empty() {
 103             return;
 104         }
 105
 106         if snippet.trim().is_empty() && !out_of_file_lines_range!(self, span) {
 107             // Keep vertical spaces within range.
 108             self.push_vertical_spaces(count_newlines(snippet));
 109             process_last_snippet(self, "", snippet);
 110         } else {
 111             self.write_snippet(span, &process_last_snippet);
 112         }
 113     }
 114
 115     fn push_vertical_spaces(&mut self, mut newline_count: usize) {
 116         let offset = self.buffer.chars().rev().take_while(|c| *c == '\n').count();
 117         let newline_upper_bound = self.config.blank_lines_upper_bound() + 1;
 118         let newline_lower_bound = self.config.blank_lines_lower_bound() + 1;
 119
 120         if newline_count + offset > newline_upper_bound {
 121             if offset >= newline_upper_bound {
 122                 newline_count = 0;
 123             } else {
 124                 newline_count = newline_upper_bound - offset;
 125             }
 126         } else if newline_count + offset < newline_lower_bound {
 127             if offset >= newline_lower_bound {
 128                 newline_count = 0;
 129             } else {
 130                 newline_count = newline_lower_bound - offset;
 131             }
 132         }
 133
 134         let blank_lines = "\n".repeat(newline_count);
 135         self.push_str(&blank_lines);
 136     }
 137
 138     fn write_snippet<F>(&mut self, span: Span, process_last_snippet: F)
 139     where
 140         F: Fn(&mut FmtVisitor<'_>, &str, &str),
 141     {
 142         // Get a snippet from the file start to the span's hi without allocating.
 143         // We need it to determine what precedes the current comment. If the comment
 144         // follows code on the same line, we won't touch it.
 145         let big_span_lo = self.snippet_provider.start_pos();
 146         let big_snippet = self.snippet_provider.entire_snippet();
 147         let big_diff = (span.lo() - big_span_lo).to_usize();
 148
 149         let snippet = self.snippet(span);
 150
 151         debug!("write_snippet `{}`", snippet);
 152
 153         self.write_snippet_inner(big_snippet, snippet, big_diff, span, process_last_snippet);
 154     }
 155
 156     fn write_snippet_inner<F>(
 157         &mut self,
 158         big_snippet: &str,
 159         old_snippet: &str,
 160         big_diff: usize,
 161         span: Span,
 162         process_last_snippet: F,
 163     ) where
 164         F: Fn(&mut FmtVisitor<'_>, &str, &str),
 165     {
 166         // Trim whitespace from the right hand side of each line.
 167         // Annoyingly, the library functions for splitting by lines etc. are not
 168         // quite right, so we must do it ourselves.
 169         let line = self.parse_sess.line_of_byte_pos(span.lo());
 170         let file_name = &self.parse_sess.span_to_filename(span);
 171         let mut status = SnippetStatus::new(line);
 172
 173         let snippet = &*transform_missing_snippet(self.config, old_snippet);
 174
 175         let slice_within_file_lines_range =
 176             |file_lines: FileLines, cur_line, s| -> (usize, usize, bool) {
 177                 let (lf_count, crlf_count) = count_lf_crlf(s);
 178                 let newline_count = lf_count + crlf_count;
 179                 let within_file_lines_range = file_lines.contains_range(
 180                     file_name,
 181                     cur_line,
 182                     // if a newline character is at the end of the slice, then the number of
 183                     // newlines needs to be decreased by 1 so that the range checked against
 184                     // the file_lines is the visual range one would expect.
 185                     cur_line + newline_count - if s.ends_with('\n') { 1 } else { 0 },
 186                 );
 187                 (lf_count, crlf_count, within_file_lines_range)
 188             };
 189         for (kind, offset, subslice) in CommentCodeSlices::new(snippet) {
 190             debug!("{:?}: {:?}", kind, subslice);
 191
 192             let (lf_count, crlf_count, within_file_lines_range) =
 193                 slice_within_file_lines_range(self.config.file_lines(), status.cur_line, subslice);
 194             let newline_count = lf_count + crlf_count;
 195             if CodeCharKind::Comment == kind && within_file_lines_range {
 196                 // 1: comment.
 197                 self.process_comment(
 198                     &mut status,
 199                     snippet,
 200                     &big_snippet[..(offset + big_diff)],
 201                     offset,
 202                     subslice,
 203                 );
 204             } else if subslice.trim().is_empty() && newline_count > 0 && within_file_lines_range {
 205                 // 2: blank lines.
 206                 self.push_vertical_spaces(newline_count);
 207                 status.cur_line += newline_count;
 208                 status.line_start = offset + lf_count + crlf_count * 2;
 209             } else {
 210                 // 3: code which we failed to format or which is not within file-lines range.
 211                 self.process_missing_code(&mut status, snippet, subslice, offset, file_name);
 212             }
 213         }
 214
 215         let last_snippet = &snippet[status.line_start..];
 216         let (_, _, within_file_lines_range) =
 217             slice_within_file_lines_range(self.config.file_lines(), status.cur_line, last_snippet);
 218         if within_file_lines_range {
 219             process_last_snippet(self, last_snippet, snippet);
 220         } else {
 221             // just append what's left
 222             self.push_str(last_snippet);
 223         }
 224     }
 225
 226     fn process_comment(
 227         &mut self,
 228         status: &mut SnippetStatus,
 229         snippet: &str,
 230         big_snippet: &str,
 231         offset: usize,
 232         subslice: &str,
 233     ) {
 234         let last_char = big_snippet
 235             .chars()
 236             .rev()
 237             .find(|rev_c| ![' ', '\t'].contains(rev_c));
 238
 239         let fix_indent = last_char.map_or(true, |rev_c| ['{', '\n'].contains(&rev_c));
 240         let mut on_same_line = false;
 241
 242         let comment_indent = if fix_indent {
 243             if let Some('{') = last_char {
 244                 self.push_str("\n");
 245             }
 246             let indent_str = self.block_indent.to_string(self.config);
 247             self.push_str(&indent_str);
 248             self.block_indent
 249         } else if self.config.version() == Version::Two && !snippet.starts_with('\n') {
 250             // The comment appears on the same line as the previous formatted code.
 251             // Assuming that comment is logically associated with that code, we want to keep it on
 252             // the same level and avoid mixing it with possible other comment.
 253             on_same_line = true;
 254             self.push_str(" ");
 255             self.block_indent
 256         } else {
 257             self.push_str(" ");
 258             Indent::from_width(self.config, last_line_width(&self.buffer))
 259         };
 260
 261         let comment_width = ::std::cmp::min(
 262             self.config.comment_width(),
 263             self.config.max_width() - self.block_indent.width(),
 264         );
 265         let comment_shape = Shape::legacy(comment_width, comment_indent);
 266
 267         if on_same_line {
 268             match subslice.find('\n') {
 269                 None => {
 270                     self.push_str(subslice);
 271                 }
 272                 Some(offset) if offset + 1 == subslice.len() => {
 273                     self.push_str(&subslice[..offset]);
 274                 }
 275                 Some(offset) => {
 276                     // keep first line as is: if it were too long and wrapped, it may get mixed
 277                     // with the other lines.
 278                     let first_line = &subslice[..offset];
 279                     self.push_str(first_line);
 280                     self.push_str(&comment_indent.to_string_with_newline(self.config));
 281
 282                     let other_lines = &subslice[offset + 1..];
 283                     let comment_str =
 284                         rewrite_comment(other_lines, false, comment_shape, self.config)
 285                             .unwrap_or_else(|| String::from(other_lines));
 286                     self.push_str(&comment_str);
 287                 }
 288             }
 289         } else {
 290             let comment_str = rewrite_comment(subslice, false, comment_shape, self.config)
 291                 .unwrap_or_else(|| String::from(subslice));
 292             self.push_str(&comment_str);
 293         }
 294
 295         status.last_wspace = None;
 296         status.line_start = offset + subslice.len();
 297
 298         // Add a newline:
 299         // - if there isn't one already
 300         // - otherwise, only if the last line is a line comment
 301         if status.line_start <= snippet.len() {
 302             match snippet[status.line_start..]
 303                 .chars()
 304                 // skip trailing whitespaces
 305                 .find(|c| !(*c == ' ' || *c == '\t'))
 306             {
 307                 Some('\n') | Some('\r') => {
 308                     if !is_last_comment_block(subslice) {
 309                         self.push_str("\n");
 310                     }
 311                 }
 312                 _ => self.push_str("\n"),
 313             }
 314         }
 315
 316         status.cur_line += count_newlines(subslice);
 317     }
 318
 319     fn process_missing_code(
 320         &mut self,
 321         status: &mut SnippetStatus,
 322         snippet: &str,
 323         subslice: &str,
 324         offset: usize,
 325         file_name: &FileName,
 326     ) {
 327         for (mut i, c) in subslice.char_indices() {
 328             i += offset;
 329
 330             if c == '\n' {
 331                 let skip_this_line = !self
 332                     .config
 333                     .file_lines()
 334                     .contains_line(file_name, status.cur_line);
 335                 if skip_this_line {
 336                     status.last_wspace = None;
 337                 }
 338
 339                 if let Some(lw) = status.last_wspace {
 340                     self.push_str(&snippet[status.line_start..lw]);
 341                     self.push_str("\n");
 342                     status.last_wspace = None;
 343                 } else {
 344                     self.push_str(&snippet[status.line_start..=i]);
 345                 }
 346
 347                 status.cur_line += 1;
 348                 status.line_start = i + 1;
 349             } else if c.is_whitespace() && status.last_wspace.is_none() {
 350                 status.last_wspace = Some(i);
 351             } else {
 352                 status.last_wspace = None;
 353             }
 354         }
 355
 356         let remaining = snippet[status.line_start..subslice.len() + offset].trim();
 357         if !remaining.is_empty() {
 358             self.push_str(&self.block_indent.to_string(self.config));
 359             self.push_str(remaining);
 360             status.line_start = subslice.len() + offset;
 361         }
 362     }
 363 }