Trait FoldProvider

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pub trait FoldProvider: Send {
    // Required methods
    fn next_visible_row(&self, row: usize, row_count: usize) -> Option<usize>;
    fn prev_visible_row(&self, row: usize) -> Option<usize>;
    fn is_row_hidden(&self, row: usize) -> bool;
    fn fold_at_row(&self, row: usize) -> Option<(usize, usize, bool)>;

    // Provided methods
    fn apply(&mut self, op: FoldOp) { ... }
    fn invalidate_range(&mut self, start_row: usize, end_row: usize) { ... }
}

Expand description

Fold-iteration + mutation trait. The engine asks “what’s the next visible row” / “is this row hidden” through this surface, and dispatches fold mutations through FoldProvider::apply, so fold storage can live wherever the host pleases (on the buffer, in a separate host-side fold tree, or absent entirely).

Introduced in 0.0.32 (Patch C-β) for read access; 0.0.38 (Patch C-δ.4) added FoldProvider::apply + FoldProvider::invalidate_range so engine call sites that used to call hjkl_buffer::Buffer::{open,close,toggle,…}_fold_at directly route through this trait now. The canonical read-only implementation crate::buffer_impl::BufferFoldProvider wraps a &hjkl_buffer::Buffer; the canonical mutable implementation crate::buffer_impl::BufferFoldProviderMut wraps a &mut hjkl_buffer::Buffer. Hosts that don’t care about folds can use NoopFoldProvider.

The engine carries a Box<dyn FoldProvider + 'a> slot today and looks up rows through it. Once Editor<B, H> flips generic (Patch C, 0.1.0) the slot moves onto Host directly.

Required Methods§

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fn next_visible_row(&self, row: usize, row_count: usize) -> Option<usize>

First visible row strictly after row, skipping hidden rows. None past the end of the buffer.

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fn prev_visible_row(&self, row: usize) -> Option<usize>

First visible row strictly before row. None past the top.

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fn is_row_hidden(&self, row: usize) -> bool

Is row currently hidden by a closed fold?

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fn fold_at_row(&self, row: usize) -> Option<(usize, usize, bool)>

Range (start_row, end_row, closed) of the fold containing row, if any. Lets za / zo / zc find their target without iterating the full fold list.

Provided Methods§

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fn apply(&mut self, op: FoldOp)

Apply a FoldOp to the underlying fold storage. Read-only providers (e.g. crate::buffer_impl::BufferFoldProvider which holds a &Buffer) and providers that don’t track folds (e.g. NoopFoldProvider) implement this as a no-op.

Default impl is a no-op so that read-only / host-stub providers don’t need to override it; mutable providers (e.g. crate::buffer_impl::BufferFoldProviderMut) override this to dispatch to the underlying buffer’s fold methods.

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fn invalidate_range(&mut self, start_row: usize, end_row: usize)

Drop every fold whose range overlaps [start_row, end_row]. Edit pipelines call this after a user edit so vim’s “edits inside a fold open it” behaviour fires. Default impl forwards to FoldProvider::apply with a FoldOp::Invalidate.