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/// A trait for reacting to an edit script from the "old" version to
/// the "new" version.
pub trait DiffHook: Sized {
type Error;
/// Called when lines with indices `old_index` (in the old version) and
/// `new_index` (in the new version) start an section equal in both
/// versions, of length `len`.
fn equal(&mut self, old_index: usize, new_index: usize, len: usize) -> Result<(), Self::Error> {
let _ = old_index;
let _ = new_index;
let _ = len;
Ok(())
}
/// Called when a section of length `old_len`, starting at `old_index`,
/// needs to be deleted from the old version.
fn delete(
&mut self,
old_index: usize,
old_len: usize,
new_index: usize,
) -> Result<(), Self::Error> {
let _ = old_index;
let _ = old_len;
let _ = new_index;
Ok(())
}
/// Called when a section of the new version, of length `new_len`
/// and starting at `new_index`, needs to be inserted at position `old_index'.
fn insert(
&mut self,
old_index: usize,
new_index: usize,
new_len: usize,
) -> Result<(), Self::Error> {
let _ = old_index;
let _ = new_index;
let _ = new_len;
Ok(())
}
/// Called when a section of the old version, starting at index
/// `old_index` and of length `old_len`, needs to be replaced with a
/// section of length `new_len`, starting at `new_index`, of the new
/// version.
///
/// The default implementations invokes `delete` and `insert`.
///
/// You can use the [`Replace`](crate::algorithms::Replace) hook to
/// automatically generate these.
fn replace(
&mut self,
old_index: usize,
old_len: usize,
new_index: usize,
new_len: usize,
) -> Result<(), Self::Error> {
self.delete(old_index, old_len, new_index)?;
self.insert(old_index, new_index, new_len)
}
/// Always called at the end of the algorithm.
fn finish(&mut self) -> Result<(), Self::Error> {
Ok(())
}
}
impl<'a, D: DiffHook + 'a> DiffHook for &'a mut D {
type Error = D::Error;
fn equal(&mut self, old_index: usize, new_index: usize, len: usize) -> Result<(), Self::Error> {
(*self).equal(old_index, new_index, len)
}
fn delete(
&mut self,
old_index: usize,
old_len: usize,
new_index: usize,
) -> Result<(), Self::Error> {
(*self).delete(old_index, old_len, new_index)
}
fn insert(
&mut self,
old_index: usize,
new_index: usize,
new_len: usize,
) -> Result<(), Self::Error> {
(*self).insert(old_index, new_index, new_len)
}
fn replace(
&mut self,
old: usize,
old_len: usize,
new: usize,
new_len: usize,
) -> Result<(), Self::Error> {
(*self).replace(old, old_len, new, new_len)
}
fn finish(&mut self) -> Result<(), Self::Error> {
(*self).finish()
}
}