vantage-diorama 0.5.7

Cached, composable, reactive surface for Vantage Vistas
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52

use std::sync::Arc;

use vantage_vista::VistaCapabilities;

use super::DioInner;

/// `TableShell` impl that backs the Vista returned by `Dio::vista()`.
///
/// Holds the shared inner Dio state so reads/writes route through the
/// Dio's machinery while schema (columns, refs, id) is forwarded to
/// the master Vista. Capability advertisement is the union of the
/// master's capabilities and what the Lens's callbacks unlock.
pub struct DioShell {
    pub(crate) dio: Arc<DioInner>,
    pub(crate) capabilities: VistaCapabilities,
}

impl DioShell {
    pub(crate) fn new(dio: Arc<DioInner>) -> Self {
        let master_caps = dio.master.capabilities().clone();
        let cbs = &dio.lens.callbacks;
        let has_on_write = cbs.on_write.is_some();
        let has_on_event = cbs.on_event.is_some();

        // Capability lifting rules (architecture doc):
        //   can_insert/update/delete = master.X OR on_write registered
        //   can_subscribe            = always true (Dio fans out events)
        //   can_invalidate           = master.can_invalidate OR on_event registered
        //   can_count                = always true (cache answers locally)
        let capabilities = VistaCapabilities {
            can_count: true,
            can_insert: master_caps.can_insert || has_on_write,
            can_update: master_caps.can_update || has_on_write,
            can_delete: master_caps.can_delete || has_on_write,
            can_subscribe: true,
            can_invalidate: master_caps.can_invalidate || has_on_event,
            // Read-side query controls reflect the cache today. Stage 5b
            // will swap in cache-aware truth for these.
            can_order: master_caps.can_order,
            can_search: master_caps.can_search,
            can_set_page_size: master_caps.can_set_page_size,
            can_fetch_page: master_caps.can_fetch_page,
            can_fetch_next: master_caps.can_fetch_next,
            // Traversal capabilities pass through from the master vista; the
            // Dio cache does not add or remove traversal modes.
            can_traverse_to_record: master_caps.can_traverse_to_record,
            can_traverse_to_set: master_caps.can_traverse_to_set,
            can_build_ref_via_script: master_caps.can_build_ref_via_script,
        };
        Self { dio, capabilities }
    }
}