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