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 use std::iter::repeat;
  13
  14 use syntax::codemap::{BytePos, FileName, Pos, Span};
  15
  16 use codemap::LineRangeUtils;
  17 use comment::{rewrite_comment, CodeCharKind, CommentCodeSlices};
  18 use config::WriteMode;
  19 use shape::{Indent, Shape};
  20 use utils::{count_newlines, last_line_width, mk_sp};
  21 use visitor::FmtVisitor;
  22
  23 struct SnippetStatus {
  24     /// An offset to the current line from the beginnig of the original snippet.
  25     line_start: usize,
  26     /// A length of trailing whitespaces on the current line.
  27     last_wspace: Option<usize>,
  28     /// The current line number.
  29     cur_line: usize,
  30 }
  31
  32 impl SnippetStatus {
  33     fn new(cur_line: usize) -> Self {
  34         SnippetStatus {
  35             line_start: 0,
  36             last_wspace: None,
  37             cur_line,
  38         }
  39     }
  40 }
  41
  42 impl<'a> FmtVisitor<'a> {
  43     fn output_at_start(&self) -> bool {
  44         self.buffer.is_empty()
  45     }
  46
  47     // TODO these format_missing methods are ugly. Refactor and add unit tests
  48     // for the central whitespace stripping loop.
  49     pub fn format_missing(&mut self, end: BytePos) {
  50         self.format_missing_inner(end, |this, last_snippet, _| this.push_str(last_snippet))
  51     }
  52
  53     pub fn format_missing_with_indent(&mut self, end: BytePos) {
  54         let config = self.config;
  55         self.format_missing_inner(end, |this, last_snippet, snippet| {
  56             this.push_str(last_snippet.trim_right());
  57             if last_snippet == snippet && !this.output_at_start() {
  58                 // No new lines in the snippet.
  59                 this.push_str("\n");
  60             }
  61             let indent = this.block_indent.to_string(config);
  62             this.push_str(&indent);
  63         })
  64     }
  65
  66     pub fn format_missing_no_indent(&mut self, end: BytePos) {
  67         self.format_missing_inner(end, |this, last_snippet, _| {
  68             this.push_str(last_snippet.trim_right());
  69         })
  70     }
  71
  72     fn format_missing_inner<F: Fn(&mut FmtVisitor, &str, &str)>(
  73         &mut self,
  74         end: BytePos,
  75         process_last_snippet: F,
  76     ) {
  77         let start = self.last_pos;
  78
  79         if start == end {
  80             // Do nothing if this is the beginning of the file.
  81             if !self.output_at_start() {
  82                 process_last_snippet(self, "", "");
  83             }
  84             return;
  85         }
  86
  87         assert!(
  88             start < end,
  89             "Request to format inverted span: {:?} to {:?}",
  90             self.codemap.lookup_char_pos(start),
  91             self.codemap.lookup_char_pos(end)
  92         );
  93
  94         self.last_pos = end;
  95         let span = mk_sp(start, end);
  96         let snippet = self.snippet(span);
  97         if snippet.trim().is_empty() && !out_of_file_lines_range!(self, span) {
  98             // Keep vertical spaces within range.
  99             self.push_vertical_spaces(count_newlines(snippet));
 100             process_last_snippet(self, "", snippet);
 101         } else {
 102             self.write_snippet(span, &process_last_snippet);
 103         }
 104     }
 105
 106     fn push_vertical_spaces(&mut self, mut newline_count: usize) {
 107         // The buffer already has a trailing newline.
 108         let offset = if self.buffer.ends_with('\n') { 0 } else { 1 };
 109         let newline_upper_bound = self.config.blank_lines_upper_bound() + offset;
 110         let newline_lower_bound = self.config.blank_lines_lower_bound() + offset;
 111         if newline_count > newline_upper_bound {
 112             newline_count = newline_upper_bound;
 113         } else if newline_count < newline_lower_bound {
 114             newline_count = newline_lower_bound;
 115         }
 116         let blank_lines: String = repeat('\n').take(newline_count).collect();
 117         self.push_str(&blank_lines);
 118     }
 119
 120     fn write_snippet<F>(&mut self, span: Span, process_last_snippet: F)
 121     where
 122         F: Fn(&mut FmtVisitor, &str, &str),
 123     {
 124         // Get a snippet from the file start to the span's hi without allocating.
 125         // We need it to determine what precedes the current comment. If the comment
 126         // follows code on the same line, we won't touch it.
 127         let big_span_lo = self.codemap.lookup_char_pos(span.lo()).file.start_pos;
 128         let local_begin = self.codemap.lookup_byte_offset(big_span_lo);
 129         let local_end = self.codemap.lookup_byte_offset(span.hi());
 130         let start_index = local_begin.pos.to_usize();
 131         let end_index = local_end.pos.to_usize();
 132         let big_snippet = &local_begin.fm.src.as_ref().unwrap()[start_index..end_index];
 133
 134         let big_diff = (span.lo() - big_span_lo).to_usize();
 135         let snippet = self.snippet(span);
 136
 137         debug!("write_snippet `{}`", snippet);
 138
 139         self.write_snippet_inner(big_snippet, big_diff, snippet, span, process_last_snippet);
 140     }
 141
 142     fn write_snippet_inner<F>(
 143         &mut self,
 144         big_snippet: &str,
 145         big_diff: usize,
 146         old_snippet: &str,
 147         span: Span,
 148         process_last_snippet: F,
 149     ) where
 150         F: Fn(&mut FmtVisitor, &str, &str),
 151     {
 152         // Trim whitespace from the right hand side of each line.
 153         // Annoyingly, the library functions for splitting by lines etc. are not
 154         // quite right, so we must do it ourselves.
 155         let char_pos = self.codemap.lookup_char_pos(span.lo());
 156         let file_name = &char_pos.file.name;
 157         let mut status = SnippetStatus::new(char_pos.line);
 158
 159         let snippet = &*match self.config.write_mode() {
 160             WriteMode::Coverage => replace_chars(old_snippet),
 161             _ => Cow::from(old_snippet),
 162         };
 163
 164         for (kind, offset, subslice) in CommentCodeSlices::new(snippet) {
 165             debug!("{:?}: {:?}", kind, subslice);
 166
 167             let newline_count = count_newlines(subslice);
 168             let within_file_lines_range = self.config.file_lines().intersects_range(
 169                 file_name,
 170                 status.cur_line,
 171                 status.cur_line + newline_count,
 172             );
 173
 174             if CodeCharKind::Comment == kind && within_file_lines_range {
 175                 // 1: comment.
 176                 self.process_comment(
 177                     &mut status,
 178                     snippet,
 179                     &big_snippet[..(offset + big_diff)],
 180                     offset,
 181                     subslice,
 182                 );
 183             } else if subslice.trim().is_empty() && newline_count > 0 && within_file_lines_range {
 184                 // 2: blank lines.
 185                 self.push_vertical_spaces(newline_count);
 186                 status.cur_line += newline_count;
 187                 status.line_start = offset + newline_count;
 188             } else {
 189                 // 3: code which we failed to format or which is not within file-lines range.
 190                 self.process_missing_code(&mut status, snippet, subslice, offset, file_name);
 191             }
 192         }
 193
 194         process_last_snippet(self, &snippet[status.line_start..], snippet);
 195     }
 196
 197     fn process_comment(
 198         &mut self,
 199         status: &mut SnippetStatus,
 200         snippet: &str,
 201         big_snippet: &str,
 202         offset: usize,
 203         subslice: &str,
 204     ) {
 205         let last_char = big_snippet
 206             .chars()
 207             .rev()
 208             .skip_while(|rev_c| [' ', '\t'].contains(rev_c))
 209             .next();
 210
 211         let fix_indent = last_char.map_or(true, |rev_c| ['{', '\n'].contains(&rev_c));
 212
 213         let comment_indent = if fix_indent {
 214             if let Some('{') = last_char {
 215                 self.push_str("\n");
 216             }
 217             let indent_str = self.block_indent.to_string(self.config);
 218             self.push_str(&indent_str);
 219             self.block_indent
 220         } else {
 221             self.push_str(" ");
 222             Indent::from_width(self.config, last_line_width(&self.buffer))
 223         };
 224
 225         let comment_width = ::std::cmp::min(
 226             self.config.comment_width(),
 227             self.config.max_width() - self.block_indent.width(),
 228         );
 229         let comment_shape = Shape::legacy(comment_width, comment_indent);
 230         let comment_str = rewrite_comment(subslice, false, comment_shape, self.config)
 231             .unwrap_or_else(|| String::from(subslice));
 232         self.push_str(&comment_str);
 233
 234         status.last_wspace = None;
 235         status.line_start = offset + subslice.len();
 236
 237         if let Some('/') = subslice.chars().nth(1) {
 238             // check that there are no contained block comments
 239             if !subslice
 240                 .split('\n')
 241                 .map(|s| s.trim_left())
 242                 .any(|s| s.len() >= 2 && &s[0..2] == "/*")
 243             {
 244                 // Add a newline after line comments
 245                 self.push_str("\n");
 246             }
 247         } else if status.line_start <= snippet.len() {
 248             // For other comments add a newline if there isn't one at the end already
 249             match snippet[status.line_start..].chars().next() {
 250                 Some('\n') | Some('\r') => (),
 251                 _ => self.push_str("\n"),
 252             }
 253         }
 254
 255         status.cur_line += count_newlines(subslice);
 256     }
 257
 258     fn process_missing_code(
 259         &mut self,
 260         status: &mut SnippetStatus,
 261         snippet: &str,
 262         subslice: &str,
 263         offset: usize,
 264         file_name: &FileName,
 265     ) {
 266         for (mut i, c) in subslice.char_indices() {
 267             i += offset;
 268
 269             if c == '\n' {
 270                 let skip_this_line = !self.config
 271                     .file_lines()
 272                     .contains_line(file_name, status.cur_line);
 273                 if skip_this_line {
 274                     status.last_wspace = None;
 275                 }
 276
 277                 if let Some(lw) = status.last_wspace {
 278                     self.push_str(&snippet[status.line_start..lw]);
 279                     self.push_str("\n");
 280                     status.last_wspace = None;
 281                 } else {
 282                     self.push_str(&snippet[status.line_start..i + 1]);
 283                 }
 284
 285                 status.cur_line += 1;
 286                 status.line_start = i + 1;
 287             } else if c.is_whitespace() && status.last_wspace.is_none() {
 288                 status.last_wspace = Some(i);
 289             } else if c == ';' && status.last_wspace.is_some() {
 290                 status.line_start = i;
 291                 status.last_wspace = None;
 292             } else {
 293                 status.last_wspace = None;
 294             }
 295         }
 296
 297         let remaining = snippet[status.line_start..subslice.len() + offset].trim();
 298         if !remaining.is_empty() {
 299             self.push_str(remaining);
 300             status.line_start = subslice.len() + offset;
 301         }
 302     }
 303 }
 304
 305 fn replace_chars(string: &str) -> Cow<str> {
 306     Cow::from(
 307         string
 308             .chars()
 309             .map(|ch| if ch.is_whitespace() { ch } else { 'X' })
 310             .collect::<String>(),
 311     )
 312 }