src/rustfmt_diff.rs

   1 use std::collections::VecDeque;
   2 use std::fmt;
   3 use std::io;
   4 use std::io::Write;
   5
   6 use crate::config::{Color, Config, Verbosity};
   7
   8 #[derive(Debug, PartialEq)]
   9 pub(crate) enum DiffLine {
  10     Context(String),
  11     Expected(String),
  12     Resulting(String),
  13 }
  14
  15 #[derive(Debug, PartialEq)]
  16 pub(crate) struct Mismatch {
  17     /// The line number in the formatted version.
  18     pub(crate) line_number: u32,
  19     /// The line number in the original version.
  20     pub(crate) line_number_orig: u32,
  21     /// The set of lines (context and old/new) in the mismatch.
  22     pub(crate) lines: Vec<DiffLine>,
  23 }
  24
  25 impl Mismatch {
  26     fn new(line_number: u32, line_number_orig: u32) -> Mismatch {
  27         Mismatch {
  28             line_number,
  29             line_number_orig,
  30             lines: Vec::new(),
  31         }
  32     }
  33 }
  34
  35 /// A single span of changed lines, with 0 or more removed lines
  36 /// and a vector of 0 or more inserted lines.
  37 #[derive(Debug, PartialEq, Eq)]
  38 pub struct ModifiedChunk {
  39     /// The first to be removed from the original text
  40     pub line_number_orig: u32,
  41     /// The number of lines which have been replaced
  42     pub lines_removed: u32,
  43     /// The new lines
  44     pub lines: Vec<String>,
  45 }
  46
  47 /// Set of changed sections of a file.
  48 #[derive(Debug, PartialEq, Eq)]
  49 pub struct ModifiedLines {
  50     /// The set of changed chunks.
  51     pub chunks: Vec<ModifiedChunk>,
  52 }
  53
  54 impl From<Vec<Mismatch>> for ModifiedLines {
  55     fn from(mismatches: Vec<Mismatch>) -> ModifiedLines {
  56         let chunks = mismatches.into_iter().map(|mismatch| {
  57             let lines = mismatch.lines.iter();
  58             let num_removed = lines
  59                 .filter(|line| matches!(line, DiffLine::Resulting(_)))
  60                 .count();
  61
  62             let new_lines = mismatch.lines.into_iter().filter_map(|line| match line {
  63                 DiffLine::Context(_) | DiffLine::Resulting(_) => None,
  64                 DiffLine::Expected(str) => Some(str),
  65             });
  66
  67             ModifiedChunk {
  68                 line_number_orig: mismatch.line_number_orig,
  69                 lines_removed: num_removed as u32,
  70                 lines: new_lines.collect(),
  71             }
  72         });
  73
  74         ModifiedLines {
  75             chunks: chunks.collect(),
  76         }
  77     }
  78 }
  79
  80 // Converts a `Mismatch` into a serialized form, which just includes
  81 // enough information to modify the original file.
  82 // Each section starts with a line with three integers, space separated:
  83 //     lineno num_removed num_added
  84 // followed by (`num_added`) lines of added text. The line numbers are
  85 // relative to the original file.
  86 impl fmt::Display for ModifiedLines {
  87     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  88         for chunk in &self.chunks {
  89             writeln!(
  90                 f,
  91                 "{} {} {}",
  92                 chunk.line_number_orig,
  93                 chunk.lines_removed,
  94                 chunk.lines.len()
  95             )?;
  96
  97             for line in &chunk.lines {
  98                 writeln!(f, "{}", line)?;
  99             }
 100         }
 101
 102         Ok(())
 103     }
 104 }
 105
 106 // Allows to convert `Display`ed `ModifiedLines` back to the structural data.
 107 impl std::str::FromStr for ModifiedLines {
 108     type Err = ();
 109
 110     fn from_str(s: &str) -> Result<ModifiedLines, ()> {
 111         let mut chunks = vec![];
 112
 113         let mut lines = s.lines();
 114         while let Some(header) = lines.next() {
 115             let mut header = header.split_whitespace();
 116             let (orig, rem, new_lines) = match (header.next(), header.next(), header.next()) {
 117                 (Some(orig), Some(removed), Some(added)) => (orig, removed, added),
 118                 _ => return Err(()),
 119             };
 120             let (orig, rem, new_lines): (u32, u32, usize) =
 121                 match (orig.parse(), rem.parse(), new_lines.parse()) {
 122                     (Ok(a), Ok(b), Ok(c)) => (a, b, c),
 123                     _ => return Err(()),
 124                 };
 125             let lines = lines.by_ref().take(new_lines);
 126             let lines: Vec<_> = lines.map(ToOwned::to_owned).collect();
 127             if lines.len() != new_lines {
 128                 return Err(());
 129             }
 130
 131             chunks.push(ModifiedChunk {
 132                 line_number_orig: orig,
 133                 lines_removed: rem,
 134                 lines,
 135             });
 136         }
 137
 138         Ok(ModifiedLines { chunks })
 139     }
 140 }
 141
 142 // This struct handles writing output to stdout and abstracts away the logic
 143 // of printing in color, if it's possible in the executing environment.
 144 pub(crate) struct OutputWriter {
 145     terminal: Option<Box<dyn term::Terminal<Output = io::Stdout>>>,
 146 }
 147
 148 impl OutputWriter {
 149     // Create a new OutputWriter instance based on the caller's preference
 150     // for colorized output and the capabilities of the terminal.
 151     pub(crate) fn new(color: Color) -> Self {
 152         if let Some(t) = term::stdout() {
 153             if color.use_colored_tty() && t.supports_color() {
 154                 return OutputWriter { terminal: Some(t) };
 155             }
 156         }
 157         OutputWriter { terminal: None }
 158     }
 159
 160     // Write output in the optionally specified color. The output is written
 161     // in the specified color if this OutputWriter instance contains a
 162     // Terminal in its `terminal` field.
 163     pub(crate) fn writeln(&mut self, msg: &str, color: Option<term::color::Color>) {
 164         match &mut self.terminal {
 165             Some(ref mut t) => {
 166                 if let Some(color) = color {
 167                     t.fg(color).unwrap();
 168                 }
 169                 writeln!(t, "{}", msg).unwrap();
 170                 if color.is_some() {
 171                     t.reset().unwrap();
 172                 }
 173             }
 174             None => println!("{}", msg),
 175         }
 176     }
 177 }
 178
 179 // Produces a diff between the expected output and actual output of rustfmt.
 180 pub(crate) fn make_diff(expected: &str, actual: &str, context_size: usize) -> Vec<Mismatch> {
 181     let mut line_number = 1;
 182     let mut line_number_orig = 1;
 183     let mut context_queue: VecDeque<&str> = VecDeque::with_capacity(context_size);
 184     let mut lines_since_mismatch = context_size + 1;
 185     let mut results = Vec::new();
 186     let mut mismatch = Mismatch::new(0, 0);
 187
 188     for result in diff::lines(expected, actual) {
 189         match result {
 190             diff::Result::Left(str) => {
 191                 if lines_since_mismatch >= context_size && lines_since_mismatch > 0 {
 192                     results.push(mismatch);
 193                     mismatch = Mismatch::new(
 194                         line_number - context_queue.len() as u32,
 195                         line_number_orig - context_queue.len() as u32,
 196                     );
 197                 }
 198
 199                 while let Some(line) = context_queue.pop_front() {
 200                     mismatch.lines.push(DiffLine::Context(line.to_owned()));
 201                 }
 202
 203                 mismatch.lines.push(DiffLine::Resulting(str.to_owned()));
 204                 line_number_orig += 1;
 205                 lines_since_mismatch = 0;
 206             }
 207             diff::Result::Right(str) => {
 208                 if lines_since_mismatch >= context_size && lines_since_mismatch > 0 {
 209                     results.push(mismatch);
 210                     mismatch = Mismatch::new(
 211                         line_number - context_queue.len() as u32,
 212                         line_number_orig - context_queue.len() as u32,
 213                     );
 214                 }
 215
 216                 while let Some(line) = context_queue.pop_front() {
 217                     mismatch.lines.push(DiffLine::Context(line.to_owned()));
 218                 }
 219
 220                 mismatch.lines.push(DiffLine::Expected(str.to_owned()));
 221                 line_number += 1;
 222                 lines_since_mismatch = 0;
 223             }
 224             diff::Result::Both(str, _) => {
 225                 if context_queue.len() >= context_size {
 226                     let _ = context_queue.pop_front();
 227                 }
 228
 229                 if lines_since_mismatch < context_size {
 230                     mismatch.lines.push(DiffLine::Context(str.to_owned()));
 231                 } else if context_size > 0 {
 232                     context_queue.push_back(str);
 233                 }
 234
 235                 line_number += 1;
 236                 line_number_orig += 1;
 237                 lines_since_mismatch += 1;
 238             }
 239         }
 240     }
 241
 242     results.push(mismatch);
 243     results.remove(0);
 244
 245     results
 246 }
 247
 248 pub(crate) fn print_diff<F>(diff: Vec<Mismatch>, get_section_title: F, config: &Config)
 249 where
 250     F: Fn(u32) -> String,
 251 {
 252     let color = config.color();
 253     let line_terminator = if config.verbose() == Verbosity::Verbose {
 254         "⏎"
 255     } else {
 256         ""
 257     };
 258
 259     let mut writer = OutputWriter::new(color);
 260
 261     for mismatch in diff {
 262         let title = get_section_title(mismatch.line_number_orig);
 263         writer.writeln(&title, None);
 264
 265         for line in mismatch.lines {
 266             match line {
 267                 DiffLine::Context(ref str) => {
 268                     writer.writeln(&format!(" {}{}", str, line_terminator), None)
 269                 }
 270                 DiffLine::Expected(ref str) => writer.writeln(
 271                     &format!("+{}{}", str, line_terminator),
 272                     Some(term::color::GREEN),
 273                 ),
 274                 DiffLine::Resulting(ref str) => writer.writeln(
 275                     &format!("-{}{}", str, line_terminator),
 276                     Some(term::color::RED),
 277                 ),
 278             }
 279         }
 280     }
 281 }
 282
 283 #[cfg(test)]
 284 mod test {
 285     use super::DiffLine::*;
 286     use super::{make_diff, Mismatch};
 287     use super::{ModifiedChunk, ModifiedLines};
 288
 289     #[test]
 290     fn diff_simple() {
 291         let src = "one\ntwo\nthree\nfour\nfive\n";
 292         let dest = "one\ntwo\ntrois\nfour\nfive\n";
 293         let diff = make_diff(src, dest, 1);
 294         assert_eq!(
 295             diff,
 296             vec![Mismatch {
 297                 line_number: 2,
 298                 line_number_orig: 2,
 299                 lines: vec![
 300                     Context("two".to_owned()),
 301                     Resulting("three".to_owned()),
 302                     Expected("trois".to_owned()),
 303                     Context("four".to_owned()),
 304                 ],
 305             }]
 306         );
 307     }
 308
 309     #[test]
 310     fn diff_simple2() {
 311         let src = "one\ntwo\nthree\nfour\nfive\nsix\nseven\n";
 312         let dest = "one\ntwo\ntrois\nfour\ncinq\nsix\nseven\n";
 313         let diff = make_diff(src, dest, 1);
 314         assert_eq!(
 315             diff,
 316             vec![
 317                 Mismatch {
 318                     line_number: 2,
 319                     line_number_orig: 2,
 320                     lines: vec![
 321                         Context("two".to_owned()),
 322                         Resulting("three".to_owned()),
 323                         Expected("trois".to_owned()),
 324                         Context("four".to_owned()),
 325                     ],
 326                 },
 327                 Mismatch {
 328                     line_number: 5,
 329                     line_number_orig: 5,
 330                     lines: vec![
 331                         Resulting("five".to_owned()),
 332                         Expected("cinq".to_owned()),
 333                         Context("six".to_owned()),
 334                     ],
 335                 },
 336             ]
 337         );
 338     }
 339
 340     #[test]
 341     fn diff_zerocontext() {
 342         let src = "one\ntwo\nthree\nfour\nfive\n";
 343         let dest = "one\ntwo\ntrois\nfour\nfive\n";
 344         let diff = make_diff(src, dest, 0);
 345         assert_eq!(
 346             diff,
 347             vec![Mismatch {
 348                 line_number: 3,
 349                 line_number_orig: 3,
 350                 lines: vec![Resulting("three".to_owned()), Expected("trois".to_owned())],
 351             }]
 352         );
 353     }
 354
 355     #[test]
 356     fn diff_trailing_newline() {
 357         let src = "one\ntwo\nthree\nfour\nfive";
 358         let dest = "one\ntwo\nthree\nfour\nfive\n";
 359         let diff = make_diff(src, dest, 1);
 360         assert_eq!(
 361             diff,
 362             vec![Mismatch {
 363                 line_number: 5,
 364                 line_number_orig: 5,
 365                 lines: vec![Context("five".to_owned()), Expected("".to_owned())],
 366             }]
 367         );
 368     }
 369
 370     #[test]
 371     fn modified_lines_from_str() {
 372         use std::str::FromStr;
 373
 374         let src = "1 6 2\nfn some() {}\nfn main() {}\n25 3 1\n  struct Test {}";
 375         let lines = ModifiedLines::from_str(src).unwrap();
 376         assert_eq!(
 377             lines,
 378             ModifiedLines {
 379                 chunks: vec![
 380                     ModifiedChunk {
 381                         line_number_orig: 1,
 382                         lines_removed: 6,
 383                         lines: vec!["fn some() {}".to_owned(), "fn main() {}".to_owned(),]
 384                     },
 385                     ModifiedChunk {
 386                         line_number_orig: 25,
 387                         lines_removed: 3,
 388                         lines: vec!["  struct Test {}".to_owned()]
 389                     }
 390                 ]
 391             }
 392         );
 393
 394         let src = "1 5 3";
 395         assert_eq!(ModifiedLines::from_str(src), Err(()));
 396
 397         let src = "1 5 3\na\nb";
 398         assert_eq!(ModifiedLines::from_str(src), Err(()));
 399     }
 400 }