Struct EdgeBelief 

#[non_exhaustive]
pub struct EdgeBelief {
    pub source_id: String,
    pub target_id: String,
    pub edge_type: String,
    pub valid_from: String,
    pub valid_to: String,
    pub branch_id: String,
}

One lineage’s belief about one edge, at the instant a fold asked (§15.2).

Why this is a struct and was a five-tuple until 0.14.5

The tuple had nowhere to put branch_id, and that was not a cosmetic shortfall: D-216 widened the four SQL folds to partition by (table_name, entity_id, branch_id) so two lineages’ beliefs about one edge would stay two rows, and then the composition immediately downstream re-collapsed them, because edge_key composed source|target|type|valid_from and the map it fed had one slot per edge key. The widened partition was handing two rows to a container that could not hold two. That is D-221, and this type is its fix.

A struct rather than a six-tuple because the next field to arrive should be additive, which is why it is also #[non_exhaustive] — the same call D-207 made for DbError, one release earlier, for the same reason. Construct these by reading a MaterializedState; the crate is the only writer.

Ordered by the tuple order of its fields, so a Vec<EdgeBelief> sorts to a canonical form and two reconstructions of the same instant are equal rather than merely equivalent — a property the snapshot suite compares on.

Constructing one

#[non_exhaustive] means no crate but this one may write the literal, and save_snapshot is public and takes a MaterializedState — so without a constructor the attribute would not make the next field additive, it would make a public function uncallable. Use EdgeBelief::new, which takes the five fields that were the tuple and defaults the sixth to the trunk, with EdgeBelief::on_branch for the rest. That is EdgeAssertion::new’s shape, deliberately: the two are the same fact travelling in opposite directions and should not need two idioms.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

source_id: String

target_id: String

edge_type: String

valid_from: String

valid_to: String

branch_id: String

The lineage that holds this belief (0.14.5, D-221).

#[serde(default = "default_branch")] so the field is additive at the bincode level. It is belt and braces — the snapshot container refuses any file whose format version is not this build’s, and 0.14.5 bumps it precisely so a state written without this field gets a named refusal rather than a deserialisation error — but a default that is right costs nothing and 'main' is what every pre-v12 row actually carried.

Implementations

impl EdgeBelief

pub fn new( source_id: impl Into<String>, target_id: impl Into<String>, edge_type: impl Into<String>, valid_from: impl Into<String>, valid_to: impl Into<String>, ) -> Self

A belief held by the trunk. Use Self::on_branch for any other.

Five arguments rather than six because main is what every belief written before 0.14.5 carried, so a caller porting a five-tuple wraps it and is correct rather than being asked a question the old shape could not have answered.

pub fn on_branch(self, branch_id: impl Into<String>) -> Self

The lineage holding this belief.

Unchecked against branches, because this type is a value and not a write: a MaterializedState naming a lineage the register has never heard of is a snapshot that will disagree with the log, which verify_snapshot_chain is there to report.

pub fn entity_id(&self) -> String

The log entity_id this belief was folded under.

Must match trg_links_log_insert’s source_id || '|' || target_id || '|' || edge_type || '|' || valid_from exactly, or a delta row will fail to replace the snapshot row it supersedes. Safe because ULIDs are Crockford base32 and edge types are [A-Z0-9]+, so | cannot occur inside a component (§4.3).

This is not a unique key across lineages and must not be used as one — see Self::belief_key, which is.

pub fn belief_key(&self) -> String

What identifies this belief: the edge key and the lineage holding it.

Trait Implementations

impl Clone for EdgeBelief

fn clone(&self) -> EdgeBelief

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for EdgeBelief

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for EdgeBelief

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for EdgeBelief

impl Hash for EdgeBelief

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for EdgeBelief

fn cmp(&self, other: &EdgeBelief) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for EdgeBelief

fn eq(&self, other: &EdgeBelief) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for EdgeBelief

fn partial_cmp(&self, other: &EdgeBelief) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Serialize for EdgeBelief

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for EdgeBelief