unfold neighbor functions to gain some speed

src/population.rs

@@ -116,8 +116,11 @@ impl Population {
 
                 for idx in lower_bound..upper_bound {
                     let human = &humans[idx];
-                    let mut neighbors: Vec<&Human> = Vec::with_capacity(8);
+                    // let mut neighbors: Vec<&Human> = Vec::with_capacity(8);
-                    if human.present_state == State::Normal {
+                    let mut new_human = human.clone();
+                    match human.present_state {
+                        State::Normal => {
+                            stats[0] += 1;
                             let possible = [
                                 (human.x - 1, human.y - 1), (human.x, human.y - 1), (human.x + 1, human.y - 1),
                                 (human.x - 1, human.y)    ,                         (human.x + 1, human.y),
@@ -126,15 +129,23 @@ impl Population {
                             for neigh_coords in possible.iter() {
                                 let neigh_idx = point_to_index(neigh_coords.0, neigh_coords.1, width, height);
                                 match neigh_idx {
-                                Some(x) => neighbors.push(&humans[x]),
+                                    Some(x) => if humans[x].present_state == State::Infected {
-                                None => {},
+                                        if roll(infection_rate) {
+                                            new_human.present_state = State::Infected;
+                                            break;
+                                        }
+                                    }
+                                    None => {}
                                 }
                             }
                         }
-                    let new_human = evolve(human, neighbors, infection_rate, curing_rate, death_rate);
+                        State::Infected => {
-                    match human.present_state {
+                            stats[1] += 1;
-                        State::Normal => { stats[0] += 1; }
+                            match die_or_cure(curing_rate, death_rate) {
-                        State::Infected => { stats[1] += 1; }
+                                Some(x) => new_human.present_state = x,
+                                None => {}
+                            }
+                        }
                         State::Immune => { stats[2] += 1; }
                         State::Dead => { stats[3] += 1; }
                     }
@@ -157,39 +168,13 @@ impl Population {
     }
 }
 
-fn evolve(human: &Human, neighbors: Vec<&Human>, infection_rate: i32, curing_rate: i32, death_rate: i32) -> Human {
+fn die_or_cure(curing_rate: i32, death_rate: i32) -> Option<State> {
-    let mut new_human = human.clone();
-    match human.present_state {
-        State::Normal => {
-            new_human.present_state = infect_by_neighbors(neighbors, infection_rate);
-        }
-        State::Infected => {
-            new_human.present_state = die_or_cure(curing_rate, death_rate);
-        }
-        State::Immune => {}
-        State::Dead => {}
-    }
-    new_human
-}
-
-fn infect_by_neighbors(neighbors: Vec<&Human>, infection_rate: i32) -> State {
-    for neighbor in neighbors.iter() {
-        if neighbor.present_state == State::Infected {
-            if roll(infection_rate) {
-                return State::Infected;
-            }
-        }
-    }
-    State::Normal
-}
-
-fn die_or_cure(curing_rate: i32, death_rate: i32) -> State {
     if roll(curing_rate) {
-        State::Immune
+        Some(State::Immune)
     } else if roll(death_rate) {
-        State::Dead
+        Some(State::Dead)
     } else {
-        State::Infected
+        None
     }
 }