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
  79             .lookup_char_pos(span.lo)
  80             .file
  81             .start_pos;
  82         let local_begin = self.codemap.lookup_byte_offset(big_span_lo);
  83         let local_end = self.codemap.lookup_byte_offset(span.hi);
  84         let start_index = local_begin.pos.to_usize();
  85         let end_index = local_end.pos.to_usize();
  86         let big_snippet = &local_begin
  87                                .fm
  88                                .src
  89                                .as_ref()
  90                                .unwrap()
  91                                [start_index..end_index];
  92
  93         let big_diff = (span.lo - big_span_lo).to_usize();
  94         let snippet = self.snippet(span);
  95
  96         debug!("write_snippet `{}`", snippet);
  97
  98         self.write_snippet_inner(big_snippet, big_diff, &snippet, process_last_snippet);
  99     }
 100
 101     fn write_snippet_inner<F>(&mut self,
 102                               big_snippet: &str,
 103                               big_diff: usize,
 104                               old_snippet: &str,
 105                               process_last_snippet: F)
 106         where F: Fn(&mut FmtVisitor, &str, &str)
 107     {
 108         // Trim whitespace from the right hand side of each line.
 109         // Annoyingly, the library functions for splitting by lines etc. are not
 110         // quite right, so we must do it ourselves.
 111         let mut line_start = 0;
 112         let mut last_wspace = None;
 113         let mut rewrite_next_comment = true;
 114
 115         fn replace_chars(string: &str) -> String {
 116             string.chars().map(|ch| if ch.is_whitespace() { ch } else { 'X' }).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                 if rewrite_next_comment {
 138                     if fix_indent {
 139                         if let Some('{') = last_char {
 140                             self.buffer.push_str("\n");
 141                         }
 142                         self.buffer.push_str(&self.block_indent.to_string(self.config));
 143                     } else {
 144                         self.buffer.push_str(" ");
 145                     }
 146
 147                     let comment_width = ::std::cmp::min(self.config.comment_width,
 148                                                         self.config.max_width -
 149                                                         self.block_indent.width());
 150
 151                     self.buffer.push_str(&rewrite_comment(subslice,
 152                                                           false,
 153                                                           Shape::legacy(comment_width,
 154                                                                         self.block_indent),
 155                                                           self.config)
 156                                                   .unwrap());
 157
 158                     last_wspace = None;
 159                     line_start = offset + subslice.len();
 160
 161                     if let Some('/') = subslice.chars().skip(1).next() {
 162                         // check that there are no contained block comments
 163                         if !subslice.split('\n').map(|s| s.trim_left()).any(|s| {
 164                                                                                 s.len() > 2 &&
 165                                                                                 &s[0..2] == "/*"
 166                                                                             }) {
 167                             // Add a newline after line comments
 168                             self.buffer.push_str("\n");
 169                         }
 170                     } else if line_start <= snippet.len() {
 171                         // For other comments add a newline if there isn't one at the end already
 172                         match snippet[line_start..].chars().next() {
 173                             Some('\n') | Some('\r') => (),
 174                             _ => self.buffer.push_str("\n"),
 175                         }
 176                     }
 177
 178                     continue;
 179                 } else {
 180                     rewrite_next_comment = false;
 181                 }
 182             }
 183
 184             for (mut i, c) in subslice.char_indices() {
 185                 i += offset;
 186
 187                 if c == '\n' {
 188                     if let Some(lw) = last_wspace {
 189                         self.buffer.push_str(&snippet[line_start..lw]);
 190                         self.buffer.push_str("\n");
 191                     } else {
 192                         self.buffer.push_str(&snippet[line_start..i + 1]);
 193                     }
 194
 195                     line_start = i + 1;
 196                     last_wspace = None;
 197                     rewrite_next_comment = rewrite_next_comment || kind == CodeCharKind::Normal;
 198                 } else if c.is_whitespace() {
 199                     if last_wspace.is_none() {
 200                         last_wspace = Some(i);
 201                     }
 202                 } else if c == ';' {
 203                     if last_wspace.is_some() {
 204                         line_start = i;
 205                     }
 206
 207                     rewrite_next_comment = rewrite_next_comment || kind == CodeCharKind::Normal;
 208                     last_wspace = None;
 209                 } else {
 210                     rewrite_next_comment = rewrite_next_comment || kind == CodeCharKind::Normal;
 211                     last_wspace = None;
 212                 }
 213             }
 214
 215             let remaining = snippet[line_start..subslice.len() + offset].trim();
 216             if !remaining.is_empty() {
 217                 self.buffer.push_str(remaining);
 218                 line_start = subslice.len() + offset;
 219                 rewrite_next_comment = rewrite_next_comment || kind == CodeCharKind::Normal;
 220             }
 221         }
 222
 223         process_last_snippet(self, &snippet[line_start..], snippet);
 224     }
 225 }