Struct Exists 

pub struct Exists {
    pub input: NodeId,
    pub rel: RelId,
    pub not: bool,
    pub parent_join_key: Vec<ColId>,
    pub output: Cell<Option<NodeId>>,
    /* private fields */
}

Exists: a relationship-size gate in the where filter sub-graph.

Fields

input: NodeId

Upstream FilterInput (the FilterStart / prior link) — for input_schema.

rel: RelId

The relationship slot to count (resolved from the subquery alias against the parent schema at build time).

not: bool

NOT EXISTS.

parent_join_key: Vec<ColId>

The parent-join-key columns — the cache key (condition.parentField).

output: Cell<Option<NodeId>>

The downstream FilterOutput chain link (wired late via Graph::set_output).

Implementations

impl Exists

pub fn new( input: NodeId, rel: RelId, parent_join_key: Vec<ColId>, not: bool, primary_key: &[ColId], ) -> Exists

pub fn begin(&self, g: &Graph)

beginFilter (exists.ts:71): just delegate downstream (the cache is reset on end, not begin).

pub fn end(&self, g: &Graph)

endFilter (exists.ts:75): reset the per-loop cache, then delegate.

pub fn filter(&self, g: &Graph, node: &Node<'_>) -> bool

filter(node) (exists.ts:80): the epoch-gated cache lookup, then #filter(node) && output.filter(node).

pub fn push_chain<'g>( &'g self, g: &'g Graph, change: Change<'g>, ) -> Vec<Change<'g>>

push (exists.ts:109). Add/Edit/Remove of the parent cannot change the child relationship’s size → #pushWithFilter. A Child Add/Remove to this relationship can flip membership → refetch the size and either pass it through filtered or convert it into a parent Add/Remove. Returns the change(s) to forward (the chassis bubbles them up; a terminal FilterEnd consumes them).