src/tools/compiletest/src/compute_diff.rs

   1 use std::collections::VecDeque;
   2
   3 #[derive(Debug, PartialEq)]
   4 pub enum DiffLine {
   5     Context(String),
   6     Expected(String),
   7     Resulting(String),
   8 }
   9
  10 #[derive(Debug, PartialEq)]
  11 pub struct Mismatch {
  12     pub line_number: u32,
  13     pub lines: Vec<DiffLine>,
  14 }
  15
  16 impl Mismatch {
  17     fn new(line_number: u32) -> Mismatch {
  18         Mismatch { line_number, lines: Vec::new() }
  19     }
  20 }
  21
  22 // Produces a diff between the expected output and actual output.
  23 pub fn make_diff(expected: &str, actual: &str, context_size: usize) -> Vec<Mismatch> {
  24     let mut line_number = 1;
  25     let mut context_queue: VecDeque<&str> = VecDeque::with_capacity(context_size);
  26     let mut lines_since_mismatch = context_size + 1;
  27     let mut results = Vec::new();
  28     let mut mismatch = Mismatch::new(0);
  29
  30     for result in diff::lines(expected, actual) {
  31         match result {
  32             diff::Result::Left(str) => {
  33                 if lines_since_mismatch >= context_size && lines_since_mismatch > 0 {
  34                     results.push(mismatch);
  35                     mismatch = Mismatch::new(line_number - context_queue.len() as u32);
  36                 }
  37
  38                 while let Some(line) = context_queue.pop_front() {
  39                     mismatch.lines.push(DiffLine::Context(line.to_owned()));
  40                 }
  41
  42                 mismatch.lines.push(DiffLine::Expected(str.to_owned()));
  43                 line_number += 1;
  44                 lines_since_mismatch = 0;
  45             }
  46             diff::Result::Right(str) => {
  47                 if lines_since_mismatch >= context_size && lines_since_mismatch > 0 {
  48                     results.push(mismatch);
  49                     mismatch = Mismatch::new(line_number - context_queue.len() as u32);
  50                 }
  51
  52                 while let Some(line) = context_queue.pop_front() {
  53                     mismatch.lines.push(DiffLine::Context(line.to_owned()));
  54                 }
  55
  56                 mismatch.lines.push(DiffLine::Resulting(str.to_owned()));
  57                 lines_since_mismatch = 0;
  58             }
  59             diff::Result::Both(str, _) => {
  60                 if context_queue.len() >= context_size {
  61                     let _ = context_queue.pop_front();
  62                 }
  63
  64                 if lines_since_mismatch < context_size {
  65                     mismatch.lines.push(DiffLine::Context(str.to_owned()));
  66                 } else if context_size > 0 {
  67                     context_queue.push_back(str);
  68                 }
  69
  70                 line_number += 1;
  71                 lines_since_mismatch += 1;
  72             }
  73         }
  74     }
  75
  76     results.push(mismatch);
  77     results.remove(0);
  78
  79     results
  80 }
  81
  82 pub(crate) fn write_diff(expected: &str, actual: &str, context_size: usize) -> String {
  83     use std::fmt::Write;
  84     let mut output = String::new();
  85     let diff_results = make_diff(expected, actual, context_size);
  86     for result in diff_results {
  87         let mut line_number = result.line_number;
  88         for line in result.lines {
  89             match line {
  90                 DiffLine::Expected(e) => {
  91                     writeln!(output, "-\t{}", e).unwrap();
  92                     line_number += 1;
  93                 }
  94                 DiffLine::Context(c) => {
  95                     writeln!(output, "{}\t{}", line_number, c).unwrap();
  96                     line_number += 1;
  97                 }
  98                 DiffLine::Resulting(r) => {
  99                     writeln!(output, "+\t{}", r).unwrap();
 100                 }
 101             }
 102         }
 103         writeln!(output).unwrap();
 104     }
 105     output
 106 }