Struct IfExistsUniConstraint 

pub struct IfExistsUniConstraint<S, A, B, K, EA, EB, KA, KB, FA, W, Sc>
where
    Sc: Score,
{ /* private fields */ }

Zero-erasure uni-constraint with existence filtering.

Scores A entities based on whether a matching B entity exists (or doesn’t exist) in another collection. Unlike join, this produces a uni-constraint over A.

Type Parameters

• S - Solution type
• A - Primary entity type (scored)
• B - Secondary entity type (checked for existence)
• K - Join key type
• EA - Extractor for A entities
• EB - Extractor for B entities
• KA - Key extractor for A
• KB - Key extractor for B
• FA - Filter on A entities
• W - Weight function for A entities
• Sc - Score type

Example

use solverforge_scoring::constraint::if_exists::{IfExistsUniConstraint, ExistenceMode};
use solverforge_scoring::api::constraint_set::IncrementalConstraint;
use solverforge_core::{ConstraintRef, ImpactType};
use solverforge_core::score::SimpleScore;

#[derive(Clone)]
struct Shift { id: usize, employee_idx: Option<usize> }

#[derive(Clone)]
struct Employee { id: usize, on_vacation: bool }

#[derive(Clone)]
struct Schedule { shifts: Vec<Shift>, employees: Vec<Employee> }

// Penalize shifts assigned to employees who are on vacation
let constraint = IfExistsUniConstraint::new(
    ConstraintRef::new("", "Vacation conflict"),
    ImpactType::Penalty,
    ExistenceMode::Exists,
    |s: &Schedule| s.shifts.as_slice(),
    |s: &Schedule| s.employees.iter().filter(|e| e.on_vacation).cloned().collect::<Vec<_>>(),
    |shift: &Shift| shift.employee_idx,
    |emp: &Employee| Some(emp.id),
    |_s: &Schedule, shift: &Shift| shift.employee_idx.is_some(),
    |_shift: &Shift| SimpleScore::of(1),
    false,
);

let schedule = Schedule {
    shifts: vec![
        Shift { id: 0, employee_idx: Some(0) },  // assigned to vacationing emp
        Shift { id: 1, employee_idx: Some(1) },  // assigned to working emp
        Shift { id: 2, employee_idx: None },     // unassigned
    ],
    employees: vec![
        Employee { id: 0, on_vacation: true },
        Employee { id: 1, on_vacation: false },
    ],
};

// Only shift 0 matches (assigned to employee on vacation)
assert_eq!(constraint.evaluate(&schedule), SimpleScore::of(-1));

Implementations

impl<S, A, B, K, EA, EB, KA, KB, FA, W, Sc> IfExistsUniConstraint<S, A, B, K, EA, EB, KA, KB, FA, W, Sc>

where S: 'static, A: Clone + 'static, B: Clone + 'static, K: Eq + Hash + Clone, EA: Fn(&S) -> &[A], EB: Fn(&S) -> Vec<B>, KA: Fn(&A) -> K, KB: Fn(&B) -> K, FA: Fn(&S, &A) -> bool, W: Fn(&A) -> Sc, Sc: Score,

pub fn new( constraint_ref: ConstraintRef, impact_type: ImpactType, mode: ExistenceMode, extractor_a: EA, extractor_b: EB, key_a: KA, key_b: KB, filter_a: FA, weight: W, is_hard: bool, ) -> Self

Creates a new if_exists/if_not_exists constraint.

Trait Implementations

impl<S, A, B, K, EA, EB, KA, KB, FA, W, Sc: Score> Debug for IfExistsUniConstraint<S, A, B, K, EA, EB, KA, KB, FA, W, Sc>

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

Formats the value using the given formatter.

impl<S, A, B, K, EA, EB, KA, KB, FA, W, Sc> IncrementalConstraint<S, Sc> for IfExistsUniConstraint<S, A, B, K, EA, EB, KA, KB, FA, W, Sc>

where S: Send + Sync + 'static, A: Clone + Send + Sync + 'static, B: Clone + Send + Sync + 'static, K: Eq + Hash + Clone + Send + Sync, EA: Fn(&S) -> &[A] + Send + Sync, EB: Fn(&S) -> Vec<B> + Send + Sync, KA: Fn(&A) -> K + Send + Sync, KB: Fn(&B) -> K + Send + Sync, FA: Fn(&S, &A) -> bool + Send + Sync, W: Fn(&A) -> Sc + Send + Sync, Sc: Score,

fn evaluate(&self, solution: &S) -> Sc

Full evaluation of this constraint.

fn match_count(&self, solution: &S) -> usize

Returns the number of matches for this constraint.

fn initialize(&mut self, solution: &S) -> Sc

Initializes internal state by inserting all entities.

fn on_insert(&mut self, solution: &S, entity_index: usize) -> Sc

Called when an entity is inserted or its variable changes.

fn on_retract(&mut self, solution: &S, entity_index: usize) -> Sc

Called when an entity is retracted or before its variable changes.

fn reset(&mut self)

Resets internal state for a new solving session.

fn name(&self) -> &str

Returns the constraint name.

fn is_hard(&self) -> bool

Returns true if this is a hard constraint.

fn constraint_ref(&self) -> ConstraintRef

Returns the constraint reference (package + name).

fn get_matches(&self, _solution: &S) -> Vec<DetailedConstraintMatch<Sc>>

Returns detailed matches with entity justifications.

fn weight(&self) -> Sc

Returns the constraint weight (score per match).