DataSource Trait

fabula::datasource -- the trait a backing store implements to make its graph queryable by the sift engine.

DataSource

pub trait DataSource {
    type N: Eq + Hash + Clone + Debug;
    type L: Eq + Hash + Clone + Debug;
    type V: PartialEq + PartialOrd + Clone + Debug;
    type T: Ord + Clone + Debug;

    fn edges_from(&self, node: &Self::N, label: &Self::L, at: &Self::T)
        -> Vec<Edge<Self::N, Self::V, Self::T>>;
    fn scan(&self, label: &Self::L, constraint: &ValueConstraint<Self::V>, at: &Self::T)
        -> Vec<Edge<Self::N, Self::V, Self::T>>;
    fn edges_from_any_time(&self, node: &Self::N, label: &Self::L)
        -> Vec<Edge<Self::N, Self::V, Self::T>>;
    fn scan_any_time(&self, label: &Self::L, constraint: &ValueConstraint<Self::V>)
        -> Vec<Edge<Self::N, Self::V, Self::T>>;
    fn now(&self) -> Self::T;
    fn value_as_node(&self, value: &Self::V) -> Option<Self::N>;
}

Associated types

Type	Bounds	Description
N	Eq + Hash + Clone + Debug	Node identifier (e.g., String, u64, EntityId).
L	Eq + Hash + Clone + Debug	Edge label (e.g., String, u32, predicate enum).
V	PartialEq + PartialOrd + Clone + Debug	Edge value. Can represent node references, strings, numbers, booleans. Often an enum wrapping N.
T	Ord + Clone + Debug	Time type (e.g., i64, chrono::NaiveDateTime).

Methods

edges_from

Follows edges from a node with a given label, active at time at.

fn edges_from(
    &self,
    node: &Self::N,
    label: &Self::L,
    at: &Self::T,
) -> Vec<Edge<Self::N, Self::V, Self::T>>

Parameter	Type	Required	Default	Description
node	&Self::N	yes	--	Source node to follow edges from.
label	&Self::L	yes	--	Edge label to filter by.
at	&Self::T	yes	--	Time point; only edges whose interval covers at are returned.

Returns: Vec<Edge<N, V, T>> -- all matching edges with source, target value, and interval.

---

scan

Finds all source nodes that have an edge with label matching constraint, active at time at. This is the index scan -- used to find starting points for pattern matching when a clause binds a new variable.

fn scan(
    &self,
    label: &Self::L,
    constraint: &ValueConstraint<Self::V>,
    at: &Self::T,
) -> Vec<Edge<Self::N, Self::V, Self::T>>

Parameter	Type	Required	Default	Description
label	&Self::L	yes	--	Edge label to filter by.
constraint	&ValueConstraint<Self::V>	yes	--	Value constraint the target must satisfy.
at	&Self::T	yes	--	Time point; only edges active at this time are returned.

Returns: Vec<Edge<N, V, T>> -- all matching edges. The source field on each edge identifies the originating node.

---

edges_from_any_time

Follows edges from a node with a given label regardless of time. Used for temporal constraint checking and negation window evaluation.

fn edges_from_any_time(
    &self,
    node: &Self::N,
    label: &Self::L,
) -> Vec<Edge<Self::N, Self::V, Self::T>>

Parameter	Type	Required	Default	Description
node	&Self::N	yes	--	Source node to follow edges from.
label	&Self::L	yes	--	Edge label to filter by.

Returns: Vec<Edge<N, V, T>> -- all edges ever valid, regardless of time.

---

scan_any_time

Scans for edges with label matching constraint at any time.

fn scan_any_time(
    &self,
    label: &Self::L,
    constraint: &ValueConstraint<Self::V>,
) -> Vec<Edge<Self::N, Self::V, Self::T>>

Parameter	Type	Required	Default	Description
label	&Self::L	yes	--	Edge label to filter by.
constraint	&ValueConstraint<Self::V>	yes	--	Value constraint the target must satisfy.

Returns: Vec<Edge<N, V, T>> -- all matching edges ever valid.

---

now

Returns the current time in the graph's time model.

fn now(&self) -> Self::T

Returns: Self::T -- the current time.

---

value_as_node

Checks whether a value represents a node reference (for traversal) vs. a literal (for comparison).

fn value_as_node(&self, value: &Self::V) -> Option<Self::N>

Parameter	Type	Required	Default	Description
value	&Self::V	yes	--	The value to inspect.

Returns: Option<Self::N> -- Some(node_id) if the value is a node reference, None if it is a literal.

---

When each method is called

Method	Batch evaluation	Incremental (on_edge_added)	Negation check
edges_from	Yes -- follows bound variables through stages.	Yes -- validates secondary clauses at event time.	Yes -- verifies remaining negation clauses.
scan	Yes -- finds starting nodes for unbound first clauses.	No.	No.
edges_from_any_time	No.	No.	No.
scan_any_time	No.	No.	Yes -- finds candidate entities for batch negation.
now	Yes -- passed to edges_from/scan as at.	Yes -- used for negation clause verification.	Yes -- implicit via batch/incremental.
value_as_node	Yes -- determines if targets are traversable.	Yes -- same.	Yes -- binding consistency checks.

---

Edge<N, V, T>

An edge returned from a DataSource query.

pub struct Edge<N, V, T> {
    pub target: V,
    pub interval: Interval<T>,
    pub source: N,
}

Fields

Name	Type	Description
source	N	The source node this edge originates from.
target	V	The target value this edge points to (node reference or literal).
interval	Interval<T>	The time interval during which this edge is/was valid.

Trait implementations

Debug, Clone (all derived, require bounds on N, V, T).

---

ValueConstraint<V>

A constraint on edge target values. Used in pattern clauses and scan queries.

use fabula::datasource::ValueConstraint;

let eq  = ValueConstraint::Eq(42);
let rng = ValueConstraint::Between(10, 20);
assert!(eq.matches(&42));
assert!(rng.matches(&15));

Variants

Variant	Description
Eq(V)	Must equal this exact value.
Lt(V)	Must be less than this value.
Gt(V)	Must be greater than this value.
Lte(V)	Must be less than or equal to this value.
Gte(V)	Must be greater than or equal to this value.
Between(V, V)	Must fall within [low, high] (inclusive on both ends).
Any	Any value matches.

Methods

matches

Tests whether a value satisfies this constraint. Requires V: PartialOrd + PartialEq.

pub fn matches(&self, value: &V) -> bool

Parameter	Type	Required	Default	Description
value	&V	yes	--	The value to test.

Returns: bool

Trait implementations

Debug, Clone, PartialEq (all derived).