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|
//! Basic diff functions
use crate::lcs;
use ansi_term::Colour;
use std::fmt;
/// Single change in original slice needed to get new slice
#[derive(Debug, PartialEq, Eq)]
pub enum DiffOp<'a, T: 'a> {
/// Appears only in second slice
Insert(&'a [T]),
/// Appears in both slices, but changed
Replace(&'a [T], &'a [T]),
/// Appears only in first slice
Remove(&'a [T]),
/// Appears on both slices
Equal(&'a [T]),
}
/// Diffs any slices which implements PartialEq
pub fn diff<'a, T: PartialEq>(x: &'a [T], y: &'a [T]) -> Vec<DiffOp<'a, T>> {
let mut ops: Vec<DiffOp<T>> = Vec::new();
let table = lcs::Table::new(x, y);
let mut i = 0;
let mut j = 0;
for m in table.matches_zero() {
let x_seq = &x[i..m.x];
let y_seq = &y[j..m.y];
if i < m.x && j < m.y {
ops.push(DiffOp::Replace(x_seq, y_seq));
} else if i < m.x {
ops.push(DiffOp::Remove(x_seq));
} else if j < m.y {
ops.push(DiffOp::Insert(y_seq));
}
i = m.x + m.len;
j = m.y + m.len;
if m.len > 0 {
ops.push(DiffOp::Equal(&x[m.x..i]));
}
}
ops
}
/// Container for slice diff result. Can be pretty-printed by Display trait.
#[derive(Debug, PartialEq, Eq)]
pub struct SliceChangeset<'a, T> {
pub diff: Vec<DiffOp<'a, T>>,
}
impl<'a, T: fmt::Display> SliceChangeset<'a, T> {
pub fn format(&self, skip_same: bool) -> String {
let mut out: Vec<String> = Vec::with_capacity(self.diff.len());
for op in &self.diff {
match op {
DiffOp::Equal(a) => {
if !skip_same || a.len() == 1 {
for i in a.iter() {
out.push(format!(" {}", i))
}
} else if a.len() > 1 {
out.push(format!(" ... skip({}) ...", a.len()));
}
}
DiffOp::Insert(a) => {
for i in a.iter() {
out.push(Colour::Green.paint(format!("+ {}", i)).to_string());
}
}
DiffOp::Remove(a) => {
for i in a.iter() {
out.push(Colour::Red.paint(format!("- {}", i)).to_string());
}
}
DiffOp::Replace(a, b) => {
let min_len = std::cmp::min(a.len(), b.len());
let max_len = std::cmp::max(a.len(), b.len());
for i in 0..min_len {
out.push(
Colour::Yellow
.paint(format!("~ {} -> {}", a[i], b[i]))
.to_string(),
);
}
for i in min_len..max_len {
if max_len == a.len() {
out.push(Colour::Red.paint(format!("- {}", a[i])).to_string());
} else {
out.push(Colour::Green.paint(format!("+ {}", b[i])).to_string());
}
}
}
}
}
format!("[\n{}\n]", out.join(",\n"))
}
}
impl<'a, T: fmt::Display> fmt::Display for SliceChangeset<'a, T> {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
write!(formatter, "{}", self.format(true))
}
}
/// Diff two arbitary slices with elements that support Display trait
pub fn diff_slice<'a, T: PartialEq + std::fmt::Display>(
x: &'a [T],
y: &'a [T],
) -> SliceChangeset<'a, T> {
let diff = diff(x, y);
SliceChangeset { diff }
}
#[test]
fn test_basic() {
assert_eq!(
diff(&[1, 2, 3, 4, 5, 6], &[2, 3, 5, 7]),
vec![
DiffOp::Remove(&[1]),
DiffOp::Equal(&[2, 3]),
DiffOp::Remove(&[4]),
DiffOp::Equal(&[5]),
DiffOp::Replace(&[6], &[7]),
]
);
assert_eq!(
diff_slice(
&["q", "a", "b", "x", "c", "d"],
&["a", "b", "y", "c", "d", "f"],
)
.diff,
vec![
DiffOp::Remove(&["q"]),
DiffOp::Equal(&["a", "b"]),
DiffOp::Replace(&["x"], &["y"]),
DiffOp::Equal(&["c", "d"]),
DiffOp::Insert(&["f"]),
]
);
assert_eq!(
diff(&["a", "c", "d", "b"], &["a", "e", "b"]),
vec![
DiffOp::Equal(&["a"]),
DiffOp::Replace(&["c", "d"], &["e"]),
DiffOp::Equal(&["b"]),
]
);
println!("Diff: {}", diff_slice(&[1, 2, 3, 4, 5, 6], &[2, 3, 5, 7]));
println!(
"Diff: {}",
diff_slice(
&["q", "a", "b", "x", "c", "d"],
&["a", "b", "y", "c", "d", "f"]
)
);
println!(
"Diff: {}",
diff_slice(&["a", "c", "d", "b"], &["a", "e", "b"])
);
}
|
