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