multibuffer-view-source

Direction: guest implements this interface · Capability: none (pure data / dispatch) · Worlds: multibuffer-view-plugin (exports)

Uses

• multibuffer-view-result from types

Functions (1)

build

build: func(view: string, args: list<string>) -> result<multibuffer-view-result, string>

Produce a pull view's excerpts, in final order.

view names which of this guest's registered views is being built; one actor and one guest instance serve them all, as with picker-source. args are the trigger's arguments verbatim — from the ex-command, the transient row, or the gr that refreshed the view.

Why the guest orders, when a scan source only supplies a sort key

The asymmetry is deliberate and it turns on who can see the whole set at ordering time. A scan guest is handed one file and cannot know where its rows land once every other file's rows interleave, so only the host can sort and the guest supplies an s64 key. A pull guest computes the entire set in this one call, so requiring a key would make the host re-sort what is already ordered — and would force orderings that are not numeric (by title, by file-then-line) through an integer that cannot express them.

An err declines the view with the guest's own message rather than opening an empty one. Declining is a first-class outcome: an empty view leaves the user to guess whether it is broken or genuinely empty.

Example — Build a view's excerpts, or decline it with a typed error · crates/lattice-plugin-host/tests/fixtures/view-guest/src/lib.rs

fn build(view: String, args: Vec<String>) -> Result<MultibufferViewResult, String> {
    if args.iter().any(|a| a == "fail") {
        return Err(format!("fixture view `{view}` declined"));
    }
    Ok(MultibufferViewResult {
        excerpts: vec![
            MultibufferViewExcerpt {
                path: "a.txt".to_string(),
                start_line: 0,
                end_line: 1,
                // Echoes the view name, so the host can assert WHICH view
                // was asked for crossed the boundary.
                header: format!("view:{view}"),
                match_count: Some(2),
            },
            MultibufferViewExcerpt {
                path: "b.txt".to_string(),
                start_line: 2,
                end_line: 2,
                // Echoes the args. Empty header on a real grouped view
                // means "same group as the row above"; here it is just the
                // second row's payload.
                header: format!("args:{}", args.join(",")),
                match_count: None,
            },
        ],
        summary: format!("{} excerpts", 2),
    })
}