48 lines
1.6 KiB
Rust
48 lines
1.6 KiB
Rust
//! Utility types to support cancellation.
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//!
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//! In a typical IDE use-case, requests and modification happen concurrently, as
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//! in the following scenario:
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//!
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//! * user types a character,
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//! * a syntax highlighting process is started
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//! * user types next character, while syntax highlighting *is still in
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//! progress*.
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//!
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//! In this situation, we want to react to modification as quickly as possible.
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//! At the same time, in-progress results are not very interesting, because they
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//! are invalidated by the edit anyway. So, we first cancel all in-flight
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//! requests, and then apply modification knowing that it won't interfere with
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//! any background processing (this bit is handled by salsa, see the
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//! `BaseDatabase::check_canceled` method).
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/// An "error" signifying that the operation was canceled.
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#[derive(Clone, PartialEq, Eq, Hash)]
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pub struct Canceled {
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_private: (),
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}
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impl Canceled {
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pub(crate) fn new() -> Canceled {
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Canceled { _private: () }
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}
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pub fn throw() -> ! {
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// We use resume and not panic here to avoid running the panic
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// hook (that is, to avoid collecting and printing backtrace).
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std::panic::resume_unwind(Box::new(Canceled::new()))
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}
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}
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impl std::fmt::Display for Canceled {
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fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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fmt.write_str("canceled")
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}
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}
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impl std::fmt::Debug for Canceled {
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fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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write!(fmt, "Canceled")
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}
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}
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impl std::error::Error for Canceled {}
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