solverforge_scoring/stream/

bi_stream.rs

/* Zero-erasure bi-constraint stream for self-join patterns.

A `BiConstraintStream` operates on pairs of entities from the same
collection (self-join), such as comparing Shifts to each other.
All type information is preserved at compile time - no Arc, no dyn.

# Example

```
use solverforge_scoring::stream::ConstraintFactory;
use solverforge_scoring::stream::joiner::equal;
use solverforge_scoring::api::constraint_set::IncrementalConstraint;
use solverforge_core::score::SoftScore;

#[derive(Clone, Debug, Hash, PartialEq, Eq)]
struct Task { team: u32 }

#[derive(Clone)]
struct Solution { tasks: Vec<Task> }

// Penalize when two tasks are on the same team
let constraint = ConstraintFactory::<Solution, SoftScore>::new()
.for_each(|s: &Solution| s.tasks.as_slice())
.join(equal(|t: &Task| t.team))
.penalize(SoftScore::of(1))
.named("Team conflict");

let solution = Solution {
tasks: vec![
Task { team: 1 },
Task { team: 1 },
Task { team: 2 },
],
};

// One pair on team 1: (0, 1) = -1 penalty
assert_eq!(constraint.evaluate(&solution), SoftScore::of(-1));
```
*/

use std::hash::Hash;

use solverforge_core::score::Score;

use crate::constraint::IncrementalBiConstraint;

use super::filter::{BiFilter, FnTriFilter, TriFilter};
use super::joiner::Joiner;
use super::tri_stream::TriConstraintStream;

super::arity_stream_macros::impl_arity_stream!(
    bi,
    BiConstraintStream,
    BiConstraintBuilder,
    IncrementalBiConstraint
);

// join method - transitions to TriConstraintStream
impl<S, A, K, E, KE, F, Sc> BiConstraintStream<S, A, K, E, KE, F, Sc>
where
    S: Send + Sync + 'static,
    A: Clone + Hash + PartialEq + Send + Sync + 'static,
    K: Eq + Hash + Clone + Send + Sync,
    E: super::collection_extract::CollectionExtract<S, Item = A>,
    KE: Fn(&S, &A, usize) -> K + Send + Sync,
    F: BiFilter<S, A, A>,
    Sc: Score + 'static,
{
    /* Joins this stream with a third element to create triples.

    # Example

    ```
    use solverforge_scoring::stream::ConstraintFactory;
    use solverforge_scoring::stream::joiner::equal;
    use solverforge_scoring::api::constraint_set::IncrementalConstraint;
    use solverforge_core::score::SoftScore;

    #[derive(Clone, Debug, Hash, PartialEq, Eq)]
    struct Task { team: u32 }

    #[derive(Clone)]
    struct Solution { tasks: Vec<Task> }

    // Penalize when three tasks are on the same team
    let constraint = ConstraintFactory::<Solution, SoftScore>::new()
    .for_each(|s: &Solution| s.tasks.as_slice())
    .join(equal(|t: &Task| t.team))
    .join(equal(|t: &Task| t.team))
    .penalize(SoftScore::of(1))
    .named("Team clustering");

    let solution = Solution {
    tasks: vec![
    Task { team: 1 },
    Task { team: 1 },
    Task { team: 1 },
    Task { team: 2 },
    ],
    };

    // One triple on team 1: (0, 1, 2) = -1 penalty
    assert_eq!(constraint.evaluate(&solution), SoftScore::of(-1));
    ```
    */
    pub fn join<J>(
        self,
        joiner: J,
    ) -> TriConstraintStream<S, A, K, E, KE, impl TriFilter<S, A, A, A>, Sc>
    where
        J: Joiner<A, A> + 'static,
        F: 'static,
    {
        let filter = self.filter;
        let combined_filter =
            move |s: &S, a: &A, b: &A, c: &A, a_idx: usize, b_idx: usize, _c_idx: usize| {
                filter.test(s, a, b, a_idx, b_idx) && joiner.matches(a, c)
            };

        TriConstraintStream::new_self_join_with_filter(
            self.extractor,
            self.key_extractor,
            FnTriFilter::new(combined_filter),
        )
    }
}

// Additional doctests for individual methods

#[cfg(doctest)]
mod doctests {
    /* # Filter method

    ```
    use solverforge_scoring::stream::ConstraintFactory;
    use solverforge_scoring::stream::joiner::equal;
    use solverforge_scoring::api::constraint_set::IncrementalConstraint;
    use solverforge_core::score::SoftScore;

    #[derive(Clone, Debug, Hash, PartialEq, Eq)]
    struct Item { group: u32, value: i32 }

    #[derive(Clone)]
    struct Solution { items: Vec<Item> }

    let constraint = ConstraintFactory::<Solution, SoftScore>::new()
    .for_each(|s: &Solution| s.items.as_slice())
    .join(equal(|i: &Item| i.group))
    .filter(|a: &Item, b: &Item| a.value + b.value > 10)
    .penalize(SoftScore::of(1))
    .named("High sum pairs");

    let solution = Solution {
    items: vec![
    Item { group: 1, value: 6 },
    Item { group: 1, value: 7 },
    ],
    };

    // 6+7=13 > 10, matches
    assert_eq!(constraint.evaluate(&solution), SoftScore::of(-1));
    ```

    # Penalize method

    ```
    use solverforge_scoring::stream::ConstraintFactory;
    use solverforge_scoring::stream::joiner::equal;
    use solverforge_scoring::api::constraint_set::IncrementalConstraint;
    use solverforge_core::score::SoftScore;

    #[derive(Clone, Debug, Hash, PartialEq, Eq)]
    struct Task { priority: u32 }

    #[derive(Clone)]
    struct Solution { tasks: Vec<Task> }

    let constraint = ConstraintFactory::<Solution, SoftScore>::new()
    .for_each(|s: &Solution| s.tasks.as_slice())
    .join(equal(|t: &Task| t.priority))
    .penalize(SoftScore::of(5))
    .named("Pair priority conflict");

    let solution = Solution {
    tasks: vec![
    Task { priority: 1 },
    Task { priority: 1 },
    ],
    };

    // One pair = -5
    assert_eq!(constraint.evaluate(&solution), SoftScore::of(-5));
    ```

    # Penalize with dynamic weight

    ```
    use solverforge_scoring::stream::ConstraintFactory;
    use solverforge_scoring::stream::joiner::equal;
    use solverforge_scoring::api::constraint_set::IncrementalConstraint;
    use solverforge_core::score::SoftScore;

    #[derive(Clone, Debug, Hash, PartialEq, Eq)]
    struct Task { team: u32, cost: i64 }

    #[derive(Clone)]
    struct Solution { tasks: Vec<Task> }

    let constraint = ConstraintFactory::<Solution, SoftScore>::new()
    .for_each(|s: &Solution| s.tasks.as_slice())
    .join(equal(|t: &Task| t.team))
    .penalize(|a: &Task, b: &Task| {
    SoftScore::of(a.cost + b.cost)
    })
    .named("Team cost");

    let solution = Solution {
    tasks: vec![
    Task { team: 1, cost: 2 },
    Task { team: 1, cost: 3 },
    ],
    };

    // Penalty: 2+3 = -5
    assert_eq!(constraint.evaluate(&solution), SoftScore::of(-5));
    ```

    # Reward method

    ```
    use solverforge_scoring::stream::ConstraintFactory;
    use solverforge_scoring::stream::joiner::equal;
    use solverforge_scoring::api::constraint_set::IncrementalConstraint;
    use solverforge_core::score::SoftScore;

    #[derive(Clone, Debug, Hash, PartialEq, Eq)]
    struct Person { team: u32 }

    #[derive(Clone)]
    struct Solution { people: Vec<Person> }

    let constraint = ConstraintFactory::<Solution, SoftScore>::new()
    .for_each(|s: &Solution| s.people.as_slice())
    .join(equal(|p: &Person| p.team))
    .reward(SoftScore::of(10))
    .named("Team synergy");

    let solution = Solution {
    people: vec![
    Person { team: 1 },
    Person { team: 1 },
    ],
    };

    // One pair = +10
    assert_eq!(constraint.evaluate(&solution), SoftScore::of(10));
    ```

    # named method

    ```
    use solverforge_scoring::stream::ConstraintFactory;
    use solverforge_scoring::stream::joiner::equal;
    use solverforge_scoring::api::constraint_set::IncrementalConstraint;
    use solverforge_core::score::SoftScore;

    #[derive(Clone, Debug, Hash, PartialEq, Eq)]
    struct Item { id: usize }

    #[derive(Clone)]
    struct Solution { items: Vec<Item> }

    let constraint = ConstraintFactory::<Solution, SoftScore>::new()
    .for_each(|s: &Solution| s.items.as_slice())
    .join(equal(|i: &Item| i.id))
    .penalize(SoftScore::of(1))
    .named("Pair items");

    assert_eq!(constraint.name(), "Pair items");
    ```
    */
}