Trait ExcerptSourceResolver 

pub trait ExcerptSourceResolver:
    Send
    + Sync
    + Debug {
    // Required methods
    fn excerpt_source(
        &self,
        buffer: BufferId,
        line: u32,
    ) -> Option<ExcerptSource>;
    fn source_line(&self, source: BufferId, line: u32) -> Option<String>;
}

Answers where a line of a composed (multibuffer) buffer came from.

Introduced in OA.23.

A multibuffer shows excerpts of other files, so a consumer holding composed coordinates cannot say which file it is looking at. The agenda is the case that needs this: rewriting a headline in place propagates through the excerpt, but writing a planning line BELOW it targets a line the view does not contain — and the view is a synthetic buffer with no path of its own.

An abstract handle for the same reason ProjectResolver is one: the plugin host must be able to answer the question without depending on lattice-multibuffer, which sits above it. Whoever owns multibuffers implements this and wires it in at boot; a host with none wired answers None, which is the honest degradation rather than a panic.

Required Methods

fn excerpt_source(&self, buffer: BufferId, line: u32) -> Option<ExcerptSource>

Where composed line of buffer came from.

None when buffer is not composed, when line is not source text (a header or separator row belongs to the view, not to any file), or when the source has no path. All three are ordinary answers: a caller asks about the cursor’s line, and a cursor can be anywhere.

fn source_line(&self, source: BufferId, line: u32) -> Option<String>

One line of a source document, without its trailing newline (slice OA.23b).

The read that pairs with acting on ExcerptSource::source. A caller deciding what to write at the line below a headline has to see what is there, and that line is outside every excerpt — so neither the composed text nor a file read answers it. A file read is wrong twice over: it misses edits the view has made and not yet saved.

source is an ExcerptSource::source, not an arbitrary buffer: None for anything no view owns.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors