Struct PropPredicate 

pub struct PropPredicate {
    pub field: String,
    pub eq: Option<Value>,
    pub in_: Option<Vec<Value>>,
}

One property test a role’s visibility may carry, beside labels.

Equality and membership only: no ranges, no negation, no nesting. A mask that can express arbitrary predicates is a query language with a security boundary attached — every operator added is another shape the resolver has to be right about, on the deny side, forever. Two operators are enough for the case that motivates them (status in ["published"]) and small enough to be obviously correct.

Exactly one of eq and in is set; validate enforces it.

Value shapes accepted on the way in

A predicate is usually hand-written, so both spellings of a value parse: the plain JSON scalar ("published", 3, true) and the tagged form the graph’s own Value serializes as ({"Str": "published"}, {"Int": 3}). They mean the same thing. Serialization always writes the tagged form, so a sidecar this binary rewrote is unambiguous no matter which one was typed.

Fields

field: String

The property to test. Never empty.

eq: Option<Value>

Single-value form: the property must equal this value.

in_: Option<Vec<Value>>

Membership form: the property must equal one of these values. An empty list matches nothing — it is a valid, fully-closed predicate.

Implementations

impl PropPredicate

pub fn holds(&self, value: Option<&Value>) -> bool

Test one node’s property value against the predicate.

visible = keys ∪ { n : label(n) ∈ labels ∧ holds(n) }.

A missing property does not hold: absent is not a match. A node that never carried the field is outside a narrowed role, which is the deny-side answer — a role narrowed to status in ["published"] must not see a document that has no status at all.

pub fn validate_named(&self, what: &str) -> Result<(), String>

Reject a predicate that does not name exactly one test of one field.

what is the argument name in the error ("visible_where" for roles, "where" for query filters).

pub fn validate(&self) -> Result<(), String>

Reject a predicate that does not name exactly one test of one field.

Trait Implementations

impl Clone for PropPredicate

fn clone(&self) -> PropPredicate

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PropPredicate

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for PropPredicate

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for PropPredicate

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for PropPredicate

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 PropPredicate