1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
//! A simple Myers diff implementation.
//!
//! This focuses on being short and simple, and the expense of being
//! inefficient. A key characteristic here is that this supports cargotest's
//! `[..]` wildcard matching. That means things like hashing can't be used.
//! Since Cargo's output tends to be small, this should be sufficient.
use std::fmt;
use std::io::Write;
use termcolor::{Ansi, Color, ColorSpec, NoColor, WriteColor};
/// A single line change to be applied to the original.
#[derive(Debug, Eq, PartialEq)]
pub enum Change<T> {
Add(usize, T),
Remove(usize, T),
Keep(usize, usize, T),
}
pub fn diff<'a, T>(a: &'a [T], b: &'a [T]) -> Vec<Change<&'a T>>
where
T: PartialEq,
{
if a.is_empty() && b.is_empty() {
return vec![];
}
let mut diff = vec![];
for (prev_x, prev_y, x, y) in backtrack(&a, &b) {
if x == prev_x {
diff.push(Change::Add(prev_y + 1, &b[prev_y]));
} else if y == prev_y {
diff.push(Change::Remove(prev_x + 1, &a[prev_x]));
} else {
diff.push(Change::Keep(prev_x + 1, prev_y + 1, &a[prev_x]));
}
}
diff.reverse();
diff
}
fn shortest_edit<T>(a: &[T], b: &[T]) -> Vec<Vec<usize>>
where
T: PartialEq,
{
let max = a.len() + b.len();
let mut v = vec![0; 2 * max + 1];
let mut trace = vec![];
for d in 0..=max {
trace.push(v.clone());
for k in (0..=(2 * d)).step_by(2) {
let mut x = if k == 0 || (k != 2 * d && v[max - d + k - 1] < v[max - d + k + 1]) {
// Move down
v[max - d + k + 1]
} else {
// Move right
v[max - d + k - 1] + 1
};
let mut y = x + d - k;
// Step diagonally as far as possible.
while x < a.len() && y < b.len() && a[x] == b[y] {
x += 1;
y += 1;
}
v[max - d + k] = x;
// Return if reached the bottom-right position.
if x >= a.len() && y >= b.len() {
return trace;
}
}
}
panic!("finished without hitting end?");
}
fn backtrack<T>(a: &[T], b: &[T]) -> Vec<(usize, usize, usize, usize)>
where
T: PartialEq,
{
let mut result = vec![];
let mut x = a.len();
let mut y = b.len();
let max = x + y;
for (d, v) in shortest_edit(a, b).iter().enumerate().rev() {
let k = x + d - y;
let prev_k = if k == 0 || (k != 2 * d && v[max - d + k - 1] < v[max - d + k + 1]) {
k + 1
} else {
k - 1
};
let prev_x = v[max - d + prev_k];
let prev_y = (prev_x + d).saturating_sub(prev_k);
while x > prev_x && y > prev_y {
result.push((x - 1, y - 1, x, y));
x -= 1;
y -= 1;
}
if d > 0 {
result.push((prev_x, prev_y, x, y));
}
x = prev_x;
y = prev_y;
}
return result;
}
pub fn colored_diff<'a, T>(a: &'a [T], b: &'a [T]) -> String
where
T: PartialEq + fmt::Display,
{
let changes = diff(a, b);
render_colored_changes(&changes)
}
pub fn render_colored_changes<T: fmt::Display>(changes: &[Change<T>]) -> String {
// termcolor is not very ergonomic, but I don't want to bring in another dependency.
let mut red = ColorSpec::new();
red.set_fg(Some(Color::Red));
let mut green = ColorSpec::new();
green.set_fg(Some(Color::Green));
let mut dim = ColorSpec::new();
dim.set_dimmed(true);
let mut v = Vec::new();
let mut result: Box<dyn WriteColor> = if crate::is_ci() {
// Don't use color on CI. Even though GitHub can display colors, it
// makes reading the raw logs more difficult.
Box::new(NoColor::new(&mut v))
} else {
Box::new(Ansi::new(&mut v))
};
for change in changes {
let (nums, sign, color, text) = match change {
Change::Add(i, s) => (format!(" {:<4} ", i), '+', &green, s),
Change::Remove(i, s) => (format!("{:<4} ", i), '-', &red, s),
Change::Keep(x, y, s) => (format!("{:<4}{:<4} ", x, y), ' ', &dim, s),
};
result.set_color(&dim).unwrap();
write!(result, "{}", nums).unwrap();
let mut bold = color.clone();
bold.set_bold(true);
result.set_color(&bold).unwrap();
write!(result, "{}", sign).unwrap();
result.reset().unwrap();
result.set_color(&color).unwrap();
write!(result, "{}", text).unwrap();
result.reset().unwrap();
writeln!(result).unwrap();
}
drop(result);
String::from_utf8(v).unwrap()
}
#[cfg(test)]
pub fn compare(a: &str, b: &str) {
let a: Vec<_> = a.chars().collect();
let b: Vec<_> = b.chars().collect();
let changes = diff(&a, &b);
let mut result = vec![];
for change in changes {
match change {
Change::Add(_, s) => result.push(*s),
Change::Remove(_, _s) => {}
Change::Keep(_, _, s) => result.push(*s),
}
}
assert_eq!(b, result);
}
#[test]
fn basic_tests() {
compare("", "");
compare("A", "");
compare("", "B");
compare("ABCABBA", "CBABAC");
}
|
