311 lines
8 KiB
Rust
311 lines
8 KiB
Rust
use crate::algorithms::hook::DiffHook;
|
|
use std::convert::Infallible;
|
|
use std::ops::Range;
|
|
|
|
/// Utility enum to capture a diff operation.
|
|
///
|
|
/// This is used by [`Capture`](crate::algorithms::Capture).
|
|
#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)]
|
|
pub enum DiffOp {
|
|
/// A segment is equal (see [`DiffHook::equal`])
|
|
Equal {
|
|
old_index: usize,
|
|
new_index: usize,
|
|
len: usize,
|
|
},
|
|
/// A segment was deleted (see [`DiffHook::delete`])
|
|
Delete {
|
|
old_index: usize,
|
|
old_len: usize,
|
|
new_index: usize,
|
|
},
|
|
/// A segment was inserted (see [`DiffHook::insert`])
|
|
Insert {
|
|
old_index: usize,
|
|
new_index: usize,
|
|
new_len: usize,
|
|
},
|
|
/// A segment was replaced (see [`DiffHook::replace`])
|
|
Replace {
|
|
old_index: usize,
|
|
old_len: usize,
|
|
new_index: usize,
|
|
new_len: usize,
|
|
},
|
|
}
|
|
|
|
/// The tag of a diff operation.
|
|
#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy, Ord, PartialOrd)]
|
|
pub enum DiffTag {
|
|
Equal,
|
|
Delete,
|
|
Insert,
|
|
Replace,
|
|
}
|
|
|
|
impl DiffOp {
|
|
/// Returns the tag of the operation.
|
|
pub fn tag(self) -> DiffTag {
|
|
self.as_tag_tuple().0
|
|
}
|
|
|
|
/// Returns the old range.
|
|
pub fn old_range(&self) -> Range<usize> {
|
|
self.as_tag_tuple().1
|
|
}
|
|
|
|
/// Returns the new range.
|
|
pub fn new_range(&self) -> Range<usize> {
|
|
self.as_tag_tuple().2
|
|
}
|
|
|
|
/// Transform the op into a tuple of diff tag and ranges.
|
|
///
|
|
/// This is useful when operating on slices. The returned format is
|
|
/// `(tag, i1..i2, j1..j2)`:
|
|
///
|
|
/// * `Replace`: `a[i1..i2]` should be replaced by `b[j1..j2]`
|
|
/// * `Delete`: `a[i1..i2]` should be deleted (`j1 == j2` in this case).
|
|
/// * `Insert`: `b[j1..j2]` should be inserted at `a[i1..i2]` (`i1 == i2` in this case).
|
|
/// * `Equal`: `a[i1..i2]` is equal to `b[j1..j2]`.
|
|
pub fn as_tag_tuple(&self) -> (DiffTag, Range<usize>, Range<usize>) {
|
|
match *self {
|
|
DiffOp::Equal {
|
|
old_index,
|
|
new_index,
|
|
len,
|
|
} => (
|
|
DiffTag::Equal,
|
|
old_index..old_index + len,
|
|
new_index..new_index + len,
|
|
),
|
|
DiffOp::Delete {
|
|
old_index,
|
|
new_index,
|
|
old_len,
|
|
} => (
|
|
DiffTag::Delete,
|
|
old_index..old_index + old_len,
|
|
new_index..new_index,
|
|
),
|
|
DiffOp::Insert {
|
|
old_index,
|
|
new_index,
|
|
new_len,
|
|
} => (
|
|
DiffTag::Insert,
|
|
old_index..old_index,
|
|
new_index..new_index + new_len,
|
|
),
|
|
DiffOp::Replace {
|
|
old_index,
|
|
old_len,
|
|
new_index,
|
|
new_len,
|
|
} => (
|
|
DiffTag::Replace,
|
|
old_index..old_index + old_len,
|
|
new_index..new_index + new_len,
|
|
),
|
|
}
|
|
}
|
|
|
|
/// Apply this operation to a diff hook.
|
|
pub fn apply_to_hook<D: DiffHook>(&self, d: &mut D) -> Result<(), D::Error> {
|
|
match *self {
|
|
DiffOp::Equal {
|
|
old_index,
|
|
new_index,
|
|
len,
|
|
} => d.equal(old_index, new_index, len),
|
|
DiffOp::Delete {
|
|
old_index,
|
|
old_len,
|
|
new_index,
|
|
} => d.delete(old_index, old_len, new_index),
|
|
DiffOp::Insert {
|
|
old_index,
|
|
new_index,
|
|
new_len,
|
|
} => d.insert(old_index, new_index, new_len),
|
|
DiffOp::Replace {
|
|
old_index,
|
|
old_len,
|
|
new_index,
|
|
new_len,
|
|
} => d.replace(old_index, old_len, new_index, new_len),
|
|
}
|
|
}
|
|
}
|
|
|
|
/// A [`DiffHook`] that captures all diff operations.
|
|
#[derive(Default, Clone)]
|
|
pub struct Capture(Vec<DiffOp>);
|
|
|
|
impl Capture {
|
|
/// Creates a new capture hook.
|
|
pub fn new() -> Capture {
|
|
Capture::default()
|
|
}
|
|
|
|
/// Converts the capture hook into a vector of ops.
|
|
pub fn into_ops(self) -> Vec<DiffOp> {
|
|
self.0
|
|
}
|
|
|
|
/// Isolate change clusters by eliminating ranges with no changes.
|
|
///
|
|
/// This is equivalent to calling [`group_diff_ops`] on [`Capture::into_ops`].
|
|
pub fn into_grouped_ops(self, n: usize) -> Vec<Vec<DiffOp>> {
|
|
group_diff_ops(self.into_ops(), n)
|
|
}
|
|
|
|
/// Accesses the captured operations.
|
|
pub fn ops(&self) -> &[DiffOp] {
|
|
&self.0
|
|
}
|
|
}
|
|
|
|
/// Isolate change clusters by eliminating ranges with no changes.
|
|
///
|
|
/// This will leave holes behind in long periods of equal ranges so that
|
|
/// you can build things like unified diffs.
|
|
pub fn group_diff_ops(mut ops: Vec<DiffOp>, n: usize) -> Vec<Vec<DiffOp>> {
|
|
if ops.is_empty() {
|
|
return vec![];
|
|
}
|
|
|
|
let mut pending_group = Vec::new();
|
|
let mut rv = Vec::new();
|
|
|
|
if let Some(DiffOp::Equal {
|
|
old_index,
|
|
new_index,
|
|
len,
|
|
}) = ops.first_mut()
|
|
{
|
|
let offset = (*len).saturating_sub(n);
|
|
*old_index += offset;
|
|
*new_index += offset;
|
|
*len -= offset;
|
|
}
|
|
|
|
if let Some(DiffOp::Equal { len, .. }) = ops.last_mut() {
|
|
*len -= (*len).saturating_sub(n);
|
|
}
|
|
|
|
for op in ops.into_iter() {
|
|
if let DiffOp::Equal {
|
|
old_index,
|
|
new_index,
|
|
len,
|
|
} = op
|
|
{
|
|
// End the current group and start a new one whenever
|
|
// there is a large range with no changes.
|
|
if len > n * 2 {
|
|
pending_group.push(DiffOp::Equal {
|
|
old_index,
|
|
new_index,
|
|
len: n,
|
|
});
|
|
rv.push(pending_group);
|
|
let offset = len.saturating_sub(n);
|
|
pending_group = vec![DiffOp::Equal {
|
|
old_index: old_index + offset,
|
|
new_index: new_index + offset,
|
|
len: len - offset,
|
|
}];
|
|
continue;
|
|
}
|
|
}
|
|
pending_group.push(op);
|
|
}
|
|
|
|
if !pending_group.is_empty() {
|
|
rv.push(pending_group);
|
|
}
|
|
|
|
rv
|
|
}
|
|
|
|
impl DiffHook for Capture {
|
|
type Error = Infallible;
|
|
|
|
fn equal(&mut self, old_index: usize, new_index: usize, len: usize) -> Result<(), Self::Error> {
|
|
self.0.push(DiffOp::Equal {
|
|
old_index,
|
|
new_index,
|
|
len,
|
|
});
|
|
Ok(())
|
|
}
|
|
|
|
fn delete(
|
|
&mut self,
|
|
old_index: usize,
|
|
old_len: usize,
|
|
new_index: usize,
|
|
) -> Result<(), Self::Error> {
|
|
self.0.push(DiffOp::Delete {
|
|
old_index,
|
|
old_len,
|
|
new_index,
|
|
});
|
|
Ok(())
|
|
}
|
|
|
|
fn insert(
|
|
&mut self,
|
|
old_index: usize,
|
|
new_index: usize,
|
|
new_len: usize,
|
|
) -> Result<(), Self::Error> {
|
|
self.0.push(DiffOp::Insert {
|
|
old_index,
|
|
new_index,
|
|
new_len,
|
|
});
|
|
Ok(())
|
|
}
|
|
|
|
fn replace(
|
|
&mut self,
|
|
old_index: usize,
|
|
old_len: usize,
|
|
new_index: usize,
|
|
new_len: usize,
|
|
) -> Result<(), Self::Error> {
|
|
self.0.push(DiffOp::Replace {
|
|
old_index,
|
|
old_len,
|
|
new_index,
|
|
new_len,
|
|
});
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn test_capture_hook_grouping() {
|
|
use crate::algorithms::{myers, Replace};
|
|
|
|
let rng = (1..100).collect::<Vec<_>>();
|
|
let mut rng_new = rng.clone();
|
|
rng_new[10] = 1000;
|
|
rng_new[13] = 1000;
|
|
rng_new[16] = 1000;
|
|
rng_new[34] = 1000;
|
|
|
|
let mut d = Replace::new(Capture::new());
|
|
myers::diff_slices(&mut d, &rng, &rng_new).unwrap();
|
|
|
|
let ops = d.into_inner().into_grouped_ops(3);
|
|
let tags = ops
|
|
.iter()
|
|
.map(|group| group.iter().map(|x| x.as_tag_tuple()).collect::<Vec<_>>())
|
|
.collect::<Vec<_>>();
|
|
|
|
insta::assert_debug_snapshot!(ops);
|
|
insta::assert_debug_snapshot!(tags);
|
|
}
|