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