src/missed_spans.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::borrow::Cow;
  12 use std::iter::repeat;
  13
  14 use syntax::codemap::{BytePos, Pos, Span};
  15
  16 use comment::{rewrite_comment, CodeCharKind, CommentCodeSlices};
  17 use config::WriteMode;
  18 use shape::{Indent, Shape};
  19 use utils::{count_newlines, mk_sp};
  20 use visitor::FmtVisitor;
  21
  22 impl<'a> FmtVisitor<'a> {
  23     fn output_at_start(&self) -> bool {
  24         self.buffer.len == 0
  25     }
  26
  27     // TODO these format_missing methods are ugly. Refactor and add unit tests
  28     // for the central whitespace stripping loop.
  29     pub fn format_missing(&mut self, end: BytePos) {
  30         self.format_missing_inner(end, |this, last_snippet, _| {
  31             this.buffer.push_str(last_snippet)
  32         })
  33     }
  34
  35     pub fn format_missing_with_indent(&mut self, end: BytePos) {
  36         let config = self.config;
  37         self.format_missing_inner(end, |this, last_snippet, snippet| {
  38             this.buffer.push_str(last_snippet.trim_right());
  39             if last_snippet == snippet && !this.output_at_start() {
  40                 // No new lines in the snippet.
  41                 this.buffer.push_str("\n");
  42             }
  43             let indent = this.block_indent.to_string(config);
  44             this.buffer.push_str(&indent);
  45         })
  46     }
  47
  48     pub fn format_missing_no_indent(&mut self, end: BytePos) {
  49         self.format_missing_inner(end, |this, last_snippet, _| {
  50             this.buffer.push_str(last_snippet.trim_right());
  51         })
  52     }
  53
  54     fn format_missing_inner<F: Fn(&mut FmtVisitor, &str, &str)>(
  55         &mut self,
  56         end: BytePos,
  57         process_last_snippet: F,
  58     ) {
  59         let start = self.last_pos;
  60
  61         if start == end {
  62             // Do nothing if this is the beginning of the file.
  63             if !self.output_at_start() {
  64                 process_last_snippet(self, "", "");
  65             }
  66             return;
  67         }
  68
  69         assert!(
  70             start < end,
  71             "Request to format inverted span: {:?} to {:?}",
  72             self.codemap.lookup_char_pos(start),
  73             self.codemap.lookup_char_pos(end)
  74         );
  75
  76         self.last_pos = end;
  77         let span = mk_sp(start, end);
  78         let snippet = self.snippet(span);
  79         if snippet.trim().is_empty() {
  80             // Keep vertical spaces within range.
  81             self.push_vertical_spaces(count_newlines(&snippet));
  82             process_last_snippet(self, "", &snippet);
  83         } else {
  84             self.write_snippet(span, &process_last_snippet);
  85         }
  86     }
  87
  88     fn push_vertical_spaces(&mut self, mut newline_count: usize) {
  89         let newline_upper_bound = self.config.blank_lines_upper_bound() + 1;
  90         let newline_lower_bound = self.config.blank_lines_lower_bound() + 1;
  91         if newline_count > newline_upper_bound {
  92             newline_count = newline_upper_bound;
  93         } else if newline_count < newline_lower_bound {
  94             newline_count = newline_lower_bound;
  95         }
  96         let blank_lines: String = repeat('\n').take(newline_count).collect();
  97         self.buffer.push_str(&blank_lines);
  98     }
  99
 100     fn write_snippet<F>(&mut self, span: Span, process_last_snippet: F)
 101     where
 102         F: Fn(&mut FmtVisitor, &str, &str),
 103     {
 104         // Get a snippet from the file start to the span's hi without allocating.
 105         // We need it to determine what precedes the current comment. If the comment
 106         // follows code on the same line, we won't touch it.
 107         let big_span_lo = self.codemap.lookup_char_pos(span.lo()).file.start_pos;
 108         let local_begin = self.codemap.lookup_byte_offset(big_span_lo);
 109         let local_end = self.codemap.lookup_byte_offset(span.hi());
 110         let start_index = local_begin.pos.to_usize();
 111         let end_index = local_end.pos.to_usize();
 112         let big_snippet = &local_begin.fm.src.as_ref().unwrap()[start_index..end_index];
 113
 114         let big_diff = (span.lo() - big_span_lo).to_usize();
 115         let snippet = self.snippet(span);
 116
 117         debug!("write_snippet `{}`", snippet);
 118
 119         self.write_snippet_inner(big_snippet, big_diff, &snippet, span, process_last_snippet);
 120     }
 121
 122     fn process_comment(
 123         &mut self,
 124         status: &mut SnippetStatus,
 125         snippet: &str,
 126         big_snippet: &str,
 127         offset: usize,
 128         big_diff: usize,
 129         subslice: &str,
 130         file_name: &str,
 131     ) -> bool {
 132         let last_char = big_snippet[..(offset + big_diff)]
 133             .chars()
 134             .rev()
 135             .skip_while(|rev_c| [' ', '\t'].contains(rev_c))
 136             .next();
 137
 138         let fix_indent = last_char.map_or(true, |rev_c| ['{', '\n'].contains(&rev_c));
 139
 140         let subslice_num_lines = count_newlines(subslice);
 141         let skip_this_range = !self.config.file_lines().intersects_range(
 142             file_name,
 143             status.cur_line,
 144             status.cur_line + subslice_num_lines,
 145         );
 146
 147         if status.rewrite_next_comment && skip_this_range {
 148             status.rewrite_next_comment = false;
 149         }
 150
 151         if status.rewrite_next_comment {
 152             if fix_indent {
 153                 if let Some('{') = last_char {
 154                     self.buffer.push_str("\n");
 155                 }
 156                 self.buffer
 157                     .push_str(&self.block_indent.to_string(self.config));
 158             } else {
 159                 self.buffer.push_str(" ");
 160             }
 161
 162             let comment_width = ::std::cmp::min(
 163                 self.config.comment_width(),
 164                 self.config.max_width() - self.block_indent.width(),
 165             );
 166             let comment_indent = Indent::from_width(self.config, self.buffer.cur_offset());
 167             let comment_shape = Shape::legacy(comment_width, comment_indent);
 168             let comment_str = rewrite_comment(subslice, false, comment_shape, self.config)
 169                 .unwrap_or_else(|| String::from(subslice));
 170             self.buffer.push_str(&comment_str);
 171
 172             status.last_wspace = None;
 173             status.line_start = offset + subslice.len();
 174
 175             if let Some('/') = subslice.chars().nth(1) {
 176                 // check that there are no contained block comments
 177                 if !subslice
 178                     .split('\n')
 179                     .map(|s| s.trim_left())
 180                     .any(|s| s.len() >= 2 && &s[0..2] == "/*")
 181                 {
 182                     // Add a newline after line comments
 183                     self.buffer.push_str("\n");
 184                 }
 185             } else if status.line_start <= snippet.len() {
 186                 // For other comments add a newline if there isn't one at the end already
 187                 match snippet[status.line_start..].chars().next() {
 188                     Some('\n') | Some('\r') => (),
 189                     _ => self.buffer.push_str("\n"),
 190                 }
 191             }
 192
 193             status.cur_line += subslice_num_lines;
 194             true
 195         } else {
 196             status.rewrite_next_comment = false;
 197             false
 198         }
 199     }
 200
 201     fn write_snippet_inner<F>(
 202         &mut self,
 203         big_snippet: &str,
 204         big_diff: usize,
 205         old_snippet: &str,
 206         span: Span,
 207         process_last_snippet: F,
 208     ) where
 209         F: Fn(&mut FmtVisitor, &str, &str),
 210     {
 211         // Trim whitespace from the right hand side of each line.
 212         // Annoyingly, the library functions for splitting by lines etc. are not
 213         // quite right, so we must do it ourselves.
 214         let char_pos = self.codemap.lookup_char_pos(span.lo());
 215         let file_name = &char_pos.file.name;
 216         let mut status = SnippetStatus::new(char_pos.line);
 217
 218         fn replace_chars<'a>(string: &'a str) -> Cow<'a, str> {
 219             if string.contains(char::is_whitespace) {
 220                 Cow::from(
 221                     string
 222                         .chars()
 223                         .map(|ch| if ch.is_whitespace() { ch } else { 'X' })
 224                         .collect::<String>(),
 225                 )
 226             } else {
 227                 Cow::from(string)
 228             }
 229         }
 230
 231         let snippet = &*match self.config.write_mode() {
 232             WriteMode::Coverage => replace_chars(old_snippet),
 233             _ => Cow::from(old_snippet),
 234         };
 235
 236         for (kind, offset, subslice) in CommentCodeSlices::new(snippet) {
 237             debug!("{:?}: {:?}", kind, subslice);
 238
 239             if let CodeCharKind::Comment = kind {
 240                 if self.process_comment(
 241                     &mut status,
 242                     snippet,
 243                     big_snippet,
 244                     offset,
 245                     big_diff,
 246                     subslice,
 247                     file_name,
 248                 ) {
 249                     continue;
 250                 }
 251             }
 252
 253             // cur_line += newline_count;
 254             // rewirte_next_comment = true;
 255
 256             for (mut i, c) in subslice.char_indices() {
 257                 i += offset;
 258
 259                 if c == '\n' {
 260                     if !self.config
 261                         .file_lines()
 262                         .contains_line(file_name, status.cur_line)
 263                     {
 264                         status.last_wspace = None;
 265                     }
 266
 267                     if let Some(lw) = status.last_wspace {
 268                         self.buffer.push_str(&snippet[status.line_start..lw]);
 269                         self.buffer.push_str("\n");
 270                     } else {
 271                         self.buffer.push_str(&snippet[status.line_start..i + 1]);
 272                     }
 273
 274                     status.cur_line += 1;
 275                     status.line_start = i + 1;
 276                     status.last_wspace = None;
 277                     status.rewrite_next_comment = true;
 278                 } else if c.is_whitespace() {
 279                     if status.last_wspace.is_none() {
 280                         status.last_wspace = Some(i);
 281                     }
 282                 } else if c == ';' {
 283                     if status.last_wspace.is_some() {
 284                         status.line_start = i;
 285                     }
 286
 287                     status.rewrite_next_comment = true;
 288                     status.last_wspace = None;
 289                 } else {
 290                     status.rewrite_next_comment = true;
 291                     status.last_wspace = None;
 292                 }
 293             }
 294
 295             let remaining = snippet[status.line_start..subslice.len() + offset].trim();
 296             if !remaining.is_empty() {
 297                 self.buffer.push_str(remaining);
 298                 status.line_start = subslice.len() + offset;
 299                 status.rewrite_next_comment = true;
 300             }
 301         }
 302
 303         process_last_snippet(self, &snippet[status.line_start..], snippet);
 304     }
 305 }
 306
 307 struct SnippetStatus {
 308     line_start: usize,
 309     last_wspace: Option<usize>,
 310     rewrite_next_comment: bool,
 311     cur_line: usize,
 312 }
 313
 314 impl SnippetStatus {
 315     fn new(cur_line: usize) -> Self {
 316         SnippetStatus {
 317             line_start: 0,
 318             last_wspace: None,
 319             rewrite_next_comment: true,
 320             cur_line,
 321         }
 322     }
 323 }