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