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This post is auto-generated from RSS feed The Rust Programming Language Forum - Latest topics. Source: SlotMap IDs with types, sub-typing?

I'm thinking about how to model a document with a slotmaps. My documents are sort of like HTML, but simpler. They have blocks, spans, images, lists, etc. If I do something like this:

new_key_type! { pub struct NodeId; }
struct Document {
    // every document node has data here
    nodes: SlotMap<NodeId, NodeBase>,
    // only spans have data here
    spans: SecondaryMap<NodeId, SpanData>,
    // only images have data here
    images: SecondaryMap<NodeId, ImageData>,
    ...
}

The NodeId is a loose type. I'd like to have something like ImageId or SpanId for when I know I'm dealing with that specific sub-type of node. But I don't see anything in the slotmap docs about how to handle this. It just shows SlotMaps and SecondaryMaps with a single key type.

I was thinking something like...

enum NodeId {
    Span(SpanId),
    Block(BlockId),
    Image(ImageId),
    ...
}

But then I have no idea how to connect that to the SlotMap and SecondaryMap types.

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