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use std::ops::Range;
use std::sync::Arc;
use helix_core::Rope;
use imara_diff::Algorithm;
use parking_lot::{Mutex, MutexGuard};
use tokio::sync::mpsc::{unbounded_channel, UnboundedSender};
use tokio::sync::{Notify, OwnedRwLockReadGuard, RwLock};
use tokio::task::JoinHandle;
use tokio::time::Instant;
use crate::diff::worker::DiffWorker;
mod line_cache;
mod worker;
type RedrawHandle = (Arc<Notify>, Arc<RwLock<()>>);
/// A rendering lock passed to the differ the prevents redraws from occurring
struct RenderLock {
pub lock: OwnedRwLockReadGuard<()>,
pub timeout: Option<Instant>,
}
struct Event {
text: Rope,
is_base: bool,
render_lock: Option<RenderLock>,
}
#[derive(Clone, Debug)]
pub struct DiffHandle {
channel: UnboundedSender<Event>,
render_lock: Arc<RwLock<()>>,
hunks: Arc<Mutex<Vec<Hunk>>>,
inverted: bool,
}
impl DiffHandle {
pub fn new(diff_base: Rope, doc: Rope, redraw_handle: RedrawHandle) -> DiffHandle {
DiffHandle::new_with_handle(diff_base, doc, redraw_handle).0
}
fn new_with_handle(
diff_base: Rope,
doc: Rope,
redraw_handle: RedrawHandle,
) -> (DiffHandle, JoinHandle<()>) {
let (sender, receiver) = unbounded_channel();
let hunks: Arc<Mutex<Vec<Hunk>>> = Arc::default();
let worker = DiffWorker {
channel: receiver,
hunks: hunks.clone(),
new_hunks: Vec::default(),
redraw_notify: redraw_handle.0,
diff_finished_notify: Arc::default(),
};
let handle = tokio::spawn(worker.run(diff_base, doc));
let differ = DiffHandle {
channel: sender,
hunks,
inverted: false,
render_lock: redraw_handle.1,
};
(differ, handle)
}
pub fn invert(&mut self) {
self.inverted = !self.inverted;
}
pub fn hunks(&self) -> FileHunks {
FileHunks {
hunks: self.hunks.lock(),
inverted: self.inverted,
}
}
/// Updates the document associated with this redraw handle
/// This function is only intended to be called from within the rendering loop
/// if called from elsewhere it may fail to acquire the render lock and panic
pub fn update_document(&self, doc: Rope, block: bool) -> bool {
// unwrap is ok here because the rendering lock is
// only exclusively locked during redraw.
// This function is only intended to be called
// from the core rendering loop where no redraw can happen in parallel
let lock = self.render_lock.clone().try_read_owned().unwrap();
let timeout = if block {
None
} else {
Some(Instant::now() + tokio::time::Duration::from_millis(SYNC_DIFF_TIMEOUT))
};
self.update_document_impl(doc, self.inverted, Some(RenderLock { lock, timeout }))
}
pub fn update_diff_base(&self, diff_base: Rope) -> bool {
self.update_document_impl(diff_base, !self.inverted, None)
}
fn update_document_impl(
&self,
text: Rope,
is_base: bool,
render_lock: Option<RenderLock>,
) -> bool {
let event = Event {
text,
is_base,
render_lock,
};
self.channel.send(event).is_ok()
}
}
/// synchronous debounce value should be low
/// so we can update synchronously most of the time
const DIFF_DEBOUNCE_TIME_SYNC: u64 = 1;
/// maximum time that rendering should be blocked until the diff finishes
const SYNC_DIFF_TIMEOUT: u64 = 12;
const DIFF_DEBOUNCE_TIME_ASYNC: u64 = 96;
const ALGORITHM: Algorithm = Algorithm::Histogram;
const MAX_DIFF_LINES: usize = 64 * u16::MAX as usize;
// cap average line length to 128 for files with MAX_DIFF_LINES
const MAX_DIFF_BYTES: usize = MAX_DIFF_LINES * 128;
/// A single change in a file potentially spanning multiple lines
/// Hunks produced by the differs are always ordered by their position
/// in the file and non-overlapping.
/// Specifically for any two hunks `x` and `y` the following properties hold:
///
/// ``` no_compile
/// assert!(x.before.end <= y.before.start);
/// assert!(x.after.end <= y.after.start);
/// ```
#[derive(PartialEq, Eq, Clone, Debug)]
pub struct Hunk {
pub before: Range<u32>,
pub after: Range<u32>,
}
impl Hunk {
/// Can be used instead of `Option::None` for better performance
/// because lines larger then `i32::MAX` are not supported by `imara-diff` anyways.
/// Has some nice properties where it usually is not necessary to check for `None` separately:
/// Empty ranges fail contains checks and also fails smaller then checks.
pub const NONE: Hunk = Hunk {
before: u32::MAX..u32::MAX,
after: u32::MAX..u32::MAX,
};
/// Inverts a change so that `before`
pub fn invert(&self) -> Hunk {
Hunk {
before: self.after.clone(),
after: self.before.clone(),
}
}
pub fn is_pure_insertion(&self) -> bool {
self.before.is_empty()
}
pub fn is_pure_removal(&self) -> bool {
self.after.is_empty()
}
}
/// A list of changes in a file sorted in ascending
/// non-overlapping order
#[derive(Debug)]
pub struct FileHunks<'a> {
hunks: MutexGuard<'a, Vec<Hunk>>,
inverted: bool,
}
impl FileHunks<'_> {
pub fn is_inverted(&self) -> bool {
self.inverted
}
/// Returns the `Hunk` for the `n`th change in this file.
/// if there is no `n`th change `Hunk::NONE` is returned instead.
pub fn nth_hunk(&self, n: u32) -> Hunk {
match self.hunks.get(n as usize) {
Some(hunk) if self.inverted => hunk.invert(),
Some(hunk) => hunk.clone(),
None => Hunk::NONE,
}
}
pub fn len(&self) -> u32 {
self.hunks.len() as u32
}
pub fn is_empty(&self) -> bool {
self.len() == 0
}
}
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