src/rustfmt_diff.rs

   1 // Copyright 2017 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::Color;
  12 use diff;
  13 use std::collections::VecDeque;
  14 use std::io;
  15 use std::io::Write;
  16 use term;
  17 use utils::use_colored_tty;
  18
  19 #[derive(Debug, PartialEq)]
  20 pub enum DiffLine {
  21     Context(String),
  22     Expected(String),
  23     Resulting(String),
  24 }
  25
  26 #[derive(Debug, PartialEq)]
  27 pub struct Mismatch {
  28     /// The line number in the formatted version.
  29     pub line_number: u32,
  30     /// The line number in the original version.
  31     pub line_number_orig: u32,
  32     /// The set of lines (context and old/new) in the mismatch.
  33     pub lines: Vec<DiffLine>,
  34 }
  35
  36 impl Mismatch {
  37     fn new(line_number: u32, line_number_orig: u32) -> Mismatch {
  38         Mismatch {
  39             line_number,
  40             line_number_orig,
  41             lines: Vec::new(),
  42         }
  43     }
  44 }
  45
  46 // This struct handles writing output to stdout and abstracts away the logic
  47 // of printing in color, if it's possible in the executing environment.
  48 pub struct OutputWriter {
  49     terminal: Option<Box<term::Terminal<Output = io::Stdout>>>,
  50 }
  51
  52 impl OutputWriter {
  53     // Create a new OutputWriter instance based on the caller's preference
  54     // for colorized output and the capabilities of the terminal.
  55     pub fn new(color: Color) -> Self {
  56         if let Some(t) = term::stdout() {
  57             if use_colored_tty(color) && t.supports_color() {
  58                 return OutputWriter { terminal: Some(t) };
  59             }
  60         }
  61         OutputWriter { terminal: None }
  62     }
  63
  64     // Write output in the optionally specified color. The output is written
  65     // in the specified color if this OutputWriter instance contains a
  66     // Terminal in its `terminal` field.
  67     pub fn writeln(&mut self, msg: &str, color: Option<term::color::Color>) {
  68         match &mut self.terminal {
  69             Some(ref mut t) => {
  70                 if let Some(color) = color {
  71                     t.fg(color).unwrap();
  72                 }
  73                 writeln!(t, "{}", msg).unwrap();
  74                 if color.is_some() {
  75                     t.reset().unwrap();
  76                 }
  77             }
  78             None => println!("{}", msg),
  79         }
  80     }
  81 }
  82
  83 // Produces a diff between the expected output and actual output of rustfmt.
  84 pub fn make_diff(expected: &str, actual: &str, context_size: usize) -> Vec<Mismatch> {
  85     let mut line_number = 1;
  86     let mut line_number_orig = 1;
  87     let mut context_queue: VecDeque<&str> = VecDeque::with_capacity(context_size);
  88     let mut lines_since_mismatch = context_size + 1;
  89     let mut results = Vec::new();
  90     let mut mismatch = Mismatch::new(0, 0);
  91
  92     for result in diff::lines(expected, actual) {
  93         match result {
  94             diff::Result::Left(str) => {
  95                 if lines_since_mismatch >= context_size && lines_since_mismatch > 0 {
  96                     results.push(mismatch);
  97                     mismatch = Mismatch::new(
  98                         line_number - context_queue.len() as u32,
  99                         line_number_orig - context_queue.len() as u32,
 100                     );
 101                 }
 102
 103                 while let Some(line) = context_queue.pop_front() {
 104                     mismatch.lines.push(DiffLine::Context(line.to_owned()));
 105                 }
 106
 107                 mismatch.lines.push(DiffLine::Resulting(str.to_owned()));
 108                 line_number_orig += 1;
 109                 lines_since_mismatch = 0;
 110             }
 111             diff::Result::Right(str) => {
 112                 if lines_since_mismatch >= context_size && lines_since_mismatch > 0 {
 113                     results.push(mismatch);
 114                     mismatch = Mismatch::new(
 115                         line_number - context_queue.len() as u32,
 116                         line_number_orig - context_queue.len() as u32,
 117                     );
 118                 }
 119
 120                 while let Some(line) = context_queue.pop_front() {
 121                     mismatch.lines.push(DiffLine::Context(line.to_owned()));
 122                 }
 123
 124                 mismatch.lines.push(DiffLine::Expected(str.to_owned()));
 125                 line_number += 1;
 126                 lines_since_mismatch = 0;
 127             }
 128             diff::Result::Both(str, _) => {
 129                 if context_queue.len() >= context_size {
 130                     let _ = context_queue.pop_front();
 131                 }
 132
 133                 if lines_since_mismatch < context_size {
 134                     mismatch.lines.push(DiffLine::Context(str.to_owned()));
 135                 } else if context_size > 0 {
 136                     context_queue.push_back(str);
 137                 }
 138
 139                 line_number += 1;
 140                 line_number_orig += 1;
 141                 lines_since_mismatch += 1;
 142             }
 143         }
 144     }
 145
 146     results.push(mismatch);
 147     results.remove(0);
 148
 149     results
 150 }
 151
 152 pub fn print_diff<F>(diff: Vec<Mismatch>, get_section_title: F, color: Color)
 153 where
 154     F: Fn(u32) -> String,
 155 {
 156     let mut writer = OutputWriter::new(color);
 157
 158     for mismatch in diff {
 159         let title = get_section_title(mismatch.line_number);
 160         writer.writeln(&format!("{}", title), None);
 161
 162         for line in mismatch.lines {
 163             match line {
 164                 DiffLine::Context(ref str) => writer.writeln(&format!(" {}⏎", str), None),
 165                 DiffLine::Expected(ref str) => {
 166                     writer.writeln(&format!("+{}⏎", str), Some(term::color::GREEN))
 167                 }
 168                 DiffLine::Resulting(ref str) => {
 169                     writer.writeln(&format!("-{}⏎", str), Some(term::color::RED))
 170                 }
 171             }
 172         }
 173     }
 174 }
 175
 176 /// Convert a Mismatch into a serialised form which just includes
 177 /// enough information to modify the original file.
 178 /// Each section starts with a line with three integers, space separated:
 179 ///     lineno num_removed num_added
 180 /// followed by (num_added) lines of added text.  The line numbers are
 181 /// relative to the original file.
 182 pub fn output_modified<W>(mut out: W, diff: Vec<Mismatch>)
 183 where
 184     W: Write,
 185 {
 186     for mismatch in diff {
 187         let (num_removed, num_added) = mismatch.lines.iter().fold((0, 0), |(rem, add), line| {
 188             match *line {
 189                 DiffLine::Context(_) => panic!("No Context expected"),
 190                 DiffLine::Expected(_) => (rem, add + 1),
 191                 DiffLine::Resulting(_) => (rem + 1, add),
 192             }
 193         });
 194         // Write a header with enough information to separate the modified lines.
 195         writeln!(
 196             out,
 197             "{} {} {}",
 198             mismatch.line_number_orig, num_removed, num_added
 199         ).unwrap();
 200
 201         for line in mismatch.lines {
 202             match line {
 203                 DiffLine::Context(_) | DiffLine::Resulting(_) => (),
 204                 DiffLine::Expected(ref str) => {
 205                     writeln!(out, "{}", str).unwrap();
 206                 }
 207             }
 208         }
 209     }
 210 }
 211
 212 #[cfg(test)]
 213 mod test {
 214     use super::DiffLine::*;
 215     use super::{make_diff, Mismatch};
 216
 217     #[test]
 218     fn diff_simple() {
 219         let src = "one\ntwo\nthree\nfour\nfive\n";
 220         let dest = "one\ntwo\ntrois\nfour\nfive\n";
 221         let diff = make_diff(src, dest, 1);
 222         assert_eq!(
 223             diff,
 224             vec![Mismatch {
 225                 line_number: 2,
 226                 line_number_orig: 2,
 227                 lines: vec![
 228                     Context("two".to_owned()),
 229                     Resulting("three".to_owned()),
 230                     Expected("trois".to_owned()),
 231                     Context("four".to_owned()),
 232                 ],
 233             }]
 234         );
 235     }
 236
 237     #[test]
 238     fn diff_simple2() {
 239         let src = "one\ntwo\nthree\nfour\nfive\nsix\nseven\n";
 240         let dest = "one\ntwo\ntrois\nfour\ncinq\nsix\nseven\n";
 241         let diff = make_diff(src, dest, 1);
 242         assert_eq!(
 243             diff,
 244             vec![
 245                 Mismatch {
 246                     line_number: 2,
 247                     line_number_orig: 2,
 248                     lines: vec![
 249                         Context("two".to_owned()),
 250                         Resulting("three".to_owned()),
 251                         Expected("trois".to_owned()),
 252                         Context("four".to_owned()),
 253                     ],
 254                 },
 255                 Mismatch {
 256                     line_number: 5,
 257                     line_number_orig: 5,
 258                     lines: vec![
 259                         Resulting("five".to_owned()),
 260                         Expected("cinq".to_owned()),
 261                         Context("six".to_owned()),
 262                     ],
 263                 },
 264             ]
 265         );
 266     }
 267
 268     #[test]
 269     fn diff_zerocontext() {
 270         let src = "one\ntwo\nthree\nfour\nfive\n";
 271         let dest = "one\ntwo\ntrois\nfour\nfive\n";
 272         let diff = make_diff(src, dest, 0);
 273         assert_eq!(
 274             diff,
 275             vec![Mismatch {
 276                 line_number: 3,
 277                 line_number_orig: 3,
 278                 lines: vec![Resulting("three".to_owned()), Expected("trois".to_owned())],
 279             }]
 280         );
 281     }
 282
 283     #[test]
 284     fn diff_trailing_newline() {
 285         let src = "one\ntwo\nthree\nfour\nfive";
 286         let dest = "one\ntwo\nthree\nfour\nfive\n";
 287         let diff = make_diff(src, dest, 1);
 288         assert_eq!(
 289             diff,
 290             vec![Mismatch {
 291                 line_number: 5,
 292                 line_number_orig: 5,
 293                 lines: vec![Context("five".to_owned()), Expected("".to_owned())],
 294             }]
 295         );
 296     }
 297 }