From c47387ebf95401195e25fd03014e113ec8655e23 Mon Sep 17 00:00:00 2001
From: Rutherther <rutherther@ditigal.xyz>
Date: Tue, 28 Oct 2025 11:14:47 +0100
Subject: [PATCH] refactor: abstract pairing to n-ary

---
 codes/eoa_lib/src/crossover.rs | 18 +++++++++---------
 codes/eoa_lib/src/evolution.rs |  6 +++---
 codes/eoa_lib/src/pairing.rs   | 18 ++++++++++--------
 3 files changed, 22 insertions(+), 20 deletions(-)

diff --git a/codes/eoa_lib/src/crossover.rs b/codes/eoa_lib/src/crossover.rs
index 2a08c7bf1c2bdc696e7921acfb68e95af2be96bc..cdc563201100c42cfb1adb1d29ae5c6b849467b5 100644
--- a/codes/eoa_lib/src/crossover.rs
+++ b/codes/eoa_lib/src/crossover.rs
@@ -5,14 +5,14 @@ use rand::{Rng, RngCore};
 
 use crate::{binary_string::BinaryString, pairing::ParentPairing, replacement::{EvaluatedPopulation, Population}};
 
-pub trait Crossover {
+pub trait Crossover<const D: usize> {
     type Chromosome;
     type Out;
 
     fn crossover(
         &self,
         parents: &EvaluatedPopulation<Self::Chromosome, Self::Out>,
-        pairs: impl Iterator<Item = ParentPairing>,
+        pairs: impl Iterator<Item = ParentPairing<D>>,
         rng: &mut dyn RngCore
     ) -> Population<Self::Chromosome>;
 }
@@ -42,7 +42,7 @@ where
 // TODO: make common functions for ovector that will be used from both BinaryOnePointCrossover and OVectorOnePointCrossover
 // for not repeating the code.
 
-impl<D, TOutput> Crossover for BinaryOnePointCrossover<D, TOutput>
+impl<D, TOutput> Crossover<2> for BinaryOnePointCrossover<D, TOutput>
 where
     D: Dim,
     DefaultAllocator: Allocator<D>
@@ -53,7 +53,7 @@ where
     fn crossover(
         &self,
         population: &EvaluatedPopulation<Self::Chromosome, Self::Out>,
-        pairs: impl Iterator<Item = ParentPairing>,
+        pairs: impl Iterator<Item = ParentPairing<2>>,
         rng: &mut dyn RngCore
     ) -> Population<Self::Chromosome> {
 
@@ -66,7 +66,7 @@ where
             let (
                 parent1,
                 parent2
-            ) = (&population.population[pair.0], &population.population[pair.1]);
+            ) = (&population.population[pair.x], &population.population[pair.y]);
 
             let (
                 chromosome1,
@@ -113,7 +113,7 @@ where
     }
 }
 
-impl<D, T, TOutput> Crossover for OVectorOnePointCrossover<D, T, TOutput>
+impl<D, T, TOutput> Crossover<2> for OVectorOnePointCrossover<D, T, TOutput>
 where
     T: Scalar,
     D: Dim,
@@ -125,7 +125,7 @@ where
     fn crossover(
         &self,
         population: &EvaluatedPopulation<Self::Chromosome, Self::Out>,
-        pairs: impl Iterator<Item = ParentPairing>,
+        pairs: impl Iterator<Item = ParentPairing<2>>,
         rng: &mut dyn RngCore
     ) -> Population<Self::Chromosome> {
 
@@ -138,7 +138,7 @@ where
             let (
                 parent1,
                 parent2
-            ) = (&population.population[pair.0], &population.population[pair.1]);
+            ) = (&population.population[pair.x], &population.population[pair.y]);
 
             let (
                 chromosome1,
@@ -157,4 +157,4 @@ where
 
         Population::from_vec(offsprings)
     }
-}
\ No newline at end of file
+}
diff --git a/codes/eoa_lib/src/evolution.rs b/codes/eoa_lib/src/evolution.rs
index 24d3739520842fa33703e4d2ec83f8f5eb326696..5303dfb137909bc57f3ed9f4961e2bba60dd0b57 100644
--- a/codes/eoa_lib/src/evolution.rs
+++ b/codes/eoa_lib/src/evolution.rs
@@ -28,13 +28,13 @@ pub struct EvolutionResult<TInput, TResult> {
     pub iterations: usize
 }
 
-pub fn evolution_algorithm<TChromosome: Clone, TResult: Clone>(
+pub fn evolution_algorithm<TChromosome: Clone, TResult: Clone, const DParents: usize>(
     initial_population: Population<TChromosome>,
     parents_count: usize,
     fitness: &impl FitnessFunction<In = TChromosome, Out = TResult>,
     selection: &impl Selection<TChromosome, TResult>,
-    pairing: &mut impl Pairing<Chromosome = TChromosome, Out = TResult>,
-    crossover: &impl Crossover<Chromosome = TChromosome, Out = TResult>,
+    pairing: &mut impl Pairing<DParents, Chromosome = TChromosome, Out = TResult>,
+    crossover: &impl Crossover<DParents, Chromosome = TChromosome, Out = TResult>,
     perturbation: &impl PerturbationOperator<Chromosome = TChromosome>,
     replacement: &impl Replacement<TChromosome, TResult>,
     better_than: &impl BetterThanOperator<TResult>,
diff --git a/codes/eoa_lib/src/pairing.rs b/codes/eoa_lib/src/pairing.rs
index 4d71f157c4cb6a2054b3955a9bfb00ebf6d2f238..45ed006e4017167885168970ed18238afc956dd7 100644
--- a/codes/eoa_lib/src/pairing.rs
+++ b/codes/eoa_lib/src/pairing.rs
@@ -1,10 +1,12 @@
 use std::marker::PhantomData;
 
+use nalgebra::{Const, OVector, SVector};
+
 use crate::replacement::EvaluatedPopulation;
 
-pub type ParentPairing = (usize, usize);
+pub type ParentPairing<const D: usize> = OVector<usize, Const<D>>;
 
-pub trait Pairing {
+pub trait Pairing<const D: usize> {
     type Chromosome;
     type Out;
 
@@ -12,7 +14,7 @@ pub trait Pairing {
         &mut self,
         population: &EvaluatedPopulation<Self::Chromosome, Self::Out>,
         parents: T
-    ) -> impl Iterator<Item = ParentPairing>;
+    ) -> impl Iterator<Item = ParentPairing<D>>;
 }
 
 pub struct AdjacentPairing<TChromosome, TOutput> {
@@ -29,7 +31,7 @@ impl<TChromosome, TOutput> AdjacentPairing<TChromosome, TOutput> {
     }
 }
 
-impl<TChromosome, TOutput> Pairing for AdjacentPairing<TChromosome, TOutput> {
+impl<TChromosome, TOutput> Pairing<2> for AdjacentPairing<TChromosome, TOutput> {
     type Chromosome = TChromosome;
     type Out = TOutput;
 
@@ -37,7 +39,7 @@ impl<TChromosome, TOutput> Pairing for AdjacentPairing<TChromosome, TOutput> {
         &mut self,
         _: &EvaluatedPopulation<Self::Chromosome, Self::Out>,
         parents: T
-    ) -> impl Iterator<Item = ParentPairing> {
+    ) -> impl Iterator<Item = ParentPairing<2>> {
         AdjacentIterator(parents, 0)
     }
 }
@@ -45,7 +47,7 @@ impl<TChromosome, TOutput> Pairing for AdjacentPairing<TChromosome, TOutput> {
 pub struct AdjacentIterator<T: Iterator<Item = usize>>(T, usize);
 
 impl<T: Iterator<Item = usize>> Iterator for AdjacentIterator<T> {
-    type Item = ParentPairing;
+    type Item = ParentPairing<2>;
 
     fn next(&mut self) -> Option<Self::Item> {
         let first = self.0.next();
@@ -55,10 +57,10 @@ impl<T: Iterator<Item = usize>> Iterator for AdjacentIterator<T> {
             // Still two elements left, return them
             (Some(first), Some(second)) => {
                 self.1 = second; // Save previous
-                Some((first, second))
+                Some(ParentPairing::<2>::new(first, second))
             },
             // Only one element remaining, return it and the previous one
-            (Some(first), _) => Some((first, self.1)),
+            (Some(first), _) => Some(ParentPairing::<2>::new(first, self.1)),
             (None, Some(_)) => panic!("Iterators cannot return something after they return none."),
             // No more elements
             _ => None