Struct IfExistsStream 

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

Zero-erasure stream for building if_exists/if_not_exists constraints.

Created by UniConstraintStream::if_exists() or if_not_exists(). Filters A entities based on whether a matching B exists.

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 (returns Vec for filtering)
• KA - Key extractor for A
• KB - Key extractor for B
• FA - Filter on A entities
• Sc - Score type

Example

use solverforge_scoring::stream::ConstraintFactory;
use solverforge_scoring::stream::joiner::equal_bi;
use solverforge_scoring::api::constraint_set::IncrementalConstraint;
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 = ConstraintFactory::<Schedule, SimpleScore>::new()
    .for_each(|s: &Schedule| s.shifts.as_slice())
    .filter(|shift: &Shift| shift.employee_idx.is_some())
    .if_exists_filtered(
        |s: &Schedule| s.employees.iter().filter(|e| e.on_vacation).cloned().collect(),
        equal_bi(
            |shift: &Shift| shift.employee_idx,
            |emp: &Employee| Some(emp.id),
        ),
    )
    .penalize(SimpleScore::of(1))
    .as_constraint("Vacation conflict");

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

// Shift 0 is assigned to employee 0 who is on vacation
assert_eq!(constraint.evaluate(&schedule), SimpleScore::of(-1));

Implementations

impl<S, A, B, K, EA, EB, KA, KB, FA, Sc> IfExistsStream<S, A, B, K, EA, EB, KA, KB, FA, 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: UniFilter<A>, Sc: Score + 'static,

pub fn penalize( self, weight: Sc, ) -> IfExistsBuilder<S, A, B, K, EA, EB, KA, KB, FA, impl Fn(&A) -> Sc + Send + Sync, Sc>

where Sc: Clone,

Penalizes each matching entity with a fixed weight.

pub fn penalize_with<W>( self, weight_fn: W, ) -> IfExistsBuilder<S, A, B, K, EA, EB, KA, KB, FA, W, Sc>

where W: Fn(&A) -> Sc + Send + Sync,

Penalizes each matching entity with a dynamic weight.

pub fn penalize_hard_with<W>( self, weight_fn: W, ) -> IfExistsBuilder<S, A, B, K, EA, EB, KA, KB, FA, W, Sc>

where W: Fn(&A) -> Sc + Send + Sync,

Penalizes each matching entity with a dynamic weight, explicitly marked as hard.

pub fn reward( self, weight: Sc, ) -> IfExistsBuilder<S, A, B, K, EA, EB, KA, KB, FA, impl Fn(&A) -> Sc + Send + Sync, Sc>

where Sc: Clone,

Rewards each matching entity with a fixed weight.

pub fn reward_with<W>( self, weight_fn: W, ) -> IfExistsBuilder<S, A, B, K, EA, EB, KA, KB, FA, W, Sc>

where W: Fn(&A) -> Sc + Send + Sync,

Rewards each matching entity with a dynamic weight.

pub fn reward_hard_with<W>( self, weight_fn: W, ) -> IfExistsBuilder<S, A, B, K, EA, EB, KA, KB, FA, W, Sc>

where W: Fn(&A) -> Sc + Send + Sync,

Rewards each matching entity with a dynamic weight, explicitly marked as hard.

Trait Implementations

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

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

Formats the value using the given formatter.