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use std::ops::Range;
/// Trait for processing the edit-scripts computed with [`diff`](crate::diff)
pub trait Sink: Sized {
type Out;
/// This method is called whenever a diff [`algorithm`](crate::Algorithm)
/// finds a change between the two processed input files.
/// A change is a continuous subsequence of [tokens](crate::intern::Token) `before` that needs
/// to be replaced by a different continuous subsequence of tokens `after` to construct the second file from the first.
///
/// These token subsequences are passed to this function in **strictly monotonically increasing order**.
/// That means that for two subsequent calls `process_change(before1, after1)` and `process_change(before2, after2)`
/// the following always holds:
///
/// ``` no_compile
/// assert!(before1.end < before2.start);
/// assert!(after1.end < after2.start);
/// ```
///
/// # Parameters
/// - **`before`** - the **position** of the removed token subsequence in the original file.
/// - **`after`** - the **position** of the inserted token subsequence in the destination file.
///
/// # Notes
////
/// A `Sink` has no function to indicate that a section of a file remains unchanged.
/// However due to the monotonically increasing calls, implementations can easily determine
/// which subsequences remain unchanged by saving `before.end`/`after.end`.
/// The range between `before.start`/`after.end` and the previous `before.end`/`after.end`
/// is always unchanged.
fn process_change(&mut self, before: Range<u32>, after: Range<u32>);
/// This function is called after all calls to `process_change` are complete
/// to obtain the final diff result
fn finish(self) -> Self::Out;
/// Utility method that constructs a [`Counter`] that tracks the total number
/// of inserted and removed tokens in the changes passed to [`process_change`](crate::Sink::process_change).
fn with_counter(self) -> Counter<Self> {
Counter::new(self)
}
}
impl<T: FnMut(Range<u32>, Range<u32>)> Sink for T {
type Out = ();
fn process_change(&mut self, before: Range<u32>, after: Range<u32>) {
self(before, after)
}
fn finish(self) -> Self::Out {}
}
impl Sink for () {
type Out = ();
fn process_change(&mut self, _before: Range<u32>, _after: Range<u32>) {}
fn finish(self) -> Self::Out {}
}
/// A [`Sink`] which wraps a different sink
/// and counts the number of `removed` and `inserted` [tokens](crate::intern::Token).
pub struct Counter<T> {
/// Total number of recorded inserted [`tokens`](crate::intern::Token).
/// Computed by summing the lengths of the `after` subsequences pass to [`process_change`](crate::Sink::process_change).
pub removals: u32,
/// Total number of recorded inserted [`tokens`](crate::intern::Token).
/// Computed by summing the lengths of the `after` subsequences pass to [`process_change`](crate::Sink::process_change).
pub insertions: u32,
/// The [`Sink`] for which the counter records [`tokens`](crate::intern::Token).
/// All calls to [`process_change`](crate::Sink::process_change) are forwarded to the `sink` by the counter.
/// After [`finish`](crate::Sink::finish) is called, this field contains the output returned by the [`finish`](crate::Sink::finish)
/// method of the wrapped [`Sink`].
pub wrapped: T,
}
impl<S: Sink> Counter<S> {
pub fn new(sink: S) -> Self {
Self {
insertions: 0,
removals: 0,
wrapped: sink,
}
}
}
impl<S: Sink> Sink for Counter<S> {
type Out = Counter<S::Out>;
fn process_change(&mut self, before: Range<u32>, after: Range<u32>) {
self.removals += before.end - before.start;
self.insertions += after.end - after.start;
self.wrapped.process_change(before, after)
}
fn finish(self) -> Self::Out {
Counter {
removals: self.removals,
insertions: self.insertions,
wrapped: self.wrapped.finish(),
}
}
}
impl<T> Counter<T> {
pub fn total(&self) -> usize {
self.insertions as usize + self.removals as usize
}
}
impl Default for Counter<()> {
fn default() -> Self {
Counter::new(())
}
}