pumpkin-propagators 0.5.0

The propagators of the Pumpkin constraint programming solver.
Documentation 
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use std::cmp::max;
use std::rc::Rc;

use pumpkin_core::predicate;
use pumpkin_core::predicates::Predicate;
use pumpkin_core::propagation::Domains;
use pumpkin_core::propagation::ReadDomains;
use pumpkin_core::variables::IntegerVariable;

use crate::cumulative::ResourceProfile;
use crate::cumulative::Task;
use crate::cumulative::time_table::explanations::get_minimal_profile;

/// Creates the propagation explanation using the big-step approach (see
/// [`CumulativeExplanationType::BigStep`])
pub(crate) fn create_big_step_propagation_explanation<Var: IntegerVariable + 'static>(
    profile: &ResourceProfile<Var>,
    capacity: i32,
    propagating_task_usage: i32,
) -> impl Iterator<Item = Predicate> {
    get_minimal_profile(
        profile,
        |task| {
            [
                predicate!(task.start_variable >= profile.end - task.processing_time + 1),
                predicate!(task.start_variable <= profile.start),
            ]
        },
        capacity,
        Some(propagating_task_usage),
    )
}

/// Creates the conflict explanation using the big-step approach (see
/// [`CumulativeExplanationType::BigStep`])
pub(crate) fn create_big_step_conflict_explanation<Var: IntegerVariable + 'static>(
    conflict_profile: &ResourceProfile<Var>,
    capacity: i32,
) -> impl Iterator<Item = Predicate> {
    get_minimal_profile(
        conflict_profile,
        move |task| {
            [
                predicate!(task.start_variable >= conflict_profile.end - task.processing_time + 1),
                predicate!(task.start_variable <= conflict_profile.start),
            ]
        },
        capacity,
        None,
    )
}

pub(crate) fn create_big_step_predicate_propagating_task_lower_bound_propagation<Var>(
    task: &Rc<Task<Var>>,
    profile: &ResourceProfile<Var>,
) -> Predicate
where
    Var: IntegerVariable + 'static,
{
    predicate!(task.start_variable >= profile.start + 1 - task.processing_time)
}

pub(crate) fn create_big_step_predicate_propagating_task_upper_bound_propagation<Var>(
    task: &Rc<Task<Var>>,
    profile: &ResourceProfile<Var>,
    context: Domains,
) -> Predicate
where
    Var: IntegerVariable + 'static,
{
    predicate!(task.start_variable <= max(context.upper_bound(&task.start_variable), profile.end))
}

#[cfg(test)]
mod tests {
    use pumpkin_core::predicate;
    use pumpkin_core::predicates::PropositionalConjunction;

    use crate::cumulative::time_table::CumulativeExplanationType;
    use crate::propagators::cumulative::time_table::propagation_handler::test_propagation_handler::TestPropagationHandler;

    #[test]
    fn test_big_step_explanation_lower_bound() {
        let mut propagation_handler =
            TestPropagationHandler::new(CumulativeExplanationType::BigStep);
        let (reason, x, y) = propagation_handler.set_up_example_lower_bound();
        let expected_reason: PropositionalConjunction = vec![
            predicate!(x >= 11),
            predicate!(y >= 15),
            predicate!(y <= 16),
        ]
        .into();
        assert_eq!(reason, expected_reason);
    }

    #[test]
    fn test_big_step_explanation_lower_bound_sequence() {
        let mut propagation_handler =
            TestPropagationHandler::new(CumulativeExplanationType::BigStep);
        let (reason, x, y, z) = propagation_handler.set_up_example_sequence_lower_bound();
        let expected_reason: PropositionalConjunction = vec![
            predicate!(x >= 11),
            predicate!(y >= 15),
            predicate!(y <= 16),
            predicate!(z >= 15),
            predicate!(z <= 19),
        ]
        .into();
        assert_eq!(reason, expected_reason);
    }

    #[test]
    fn test_big_step_explanation_upper_bound() {
        let mut propagation_handler =
            TestPropagationHandler::new(CumulativeExplanationType::BigStep);
        let (reason, x, y) = propagation_handler.set_up_example_upper_bound();
        let expected_reason: PropositionalConjunction = vec![
            predicate!(x <= 18),
            predicate!(y >= 15),
            predicate!(y <= 16),
        ]
        .into();
        assert_eq!(reason, expected_reason);
    }

    #[test]
    fn test_big_step_explanation_upper_bound_sequence() {
        let mut propagation_handler =
            TestPropagationHandler::new(CumulativeExplanationType::BigStep);
        let (reason, x, y, z) = propagation_handler.set_up_example_sequence_upper_bound();
        let expected_reason: PropositionalConjunction = vec![
            predicate!(x <= 18),
            predicate!(y >= 15),
            predicate!(y <= 16),
            predicate!(z >= 7),
            predicate!(z <= 9),
        ]
        .into();
        assert_eq!(reason, expected_reason);
    }

    #[test]
    fn test_conflict_big_step() {
        let mut propagation_handler =
            TestPropagationHandler::new(CumulativeExplanationType::BigStep);
        let (reason, y) = propagation_handler.set_up_conflict_example();
        let expected_reason: PropositionalConjunction =
            vec![predicate!(y >= 14), predicate!(y <= 15)].into();
        assert_eq!(reason, expected_reason);
    }
}