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pub use coord_2d::{Coord, Size}; pub use direction::CardinalDirection; pub use grid_search_cardinal_common::{coord::UnitCoord, path::Path, step::Step}; use grid_search_cardinal_common::{ coord::UNIT_COORDS, seen_set::{SeenSet, Visit}, }; #[cfg(feature = "serialize")] use serde::{Deserialize, Serialize}; use std::collections::VecDeque; pub type Depth = u32; struct Node { step: Step, depth: Depth, } pub struct Context { seen_set: SeenSet, queue: VecDeque<Node>, } #[cfg(feature = "serialize")] impl Serialize for Context { fn serialize<S: serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> { self.seen_set.size().serialize(s) } } #[cfg(feature = "serialize")] impl<'a> Deserialize<'a> for Context { fn deserialize<D: serde::Deserializer<'a>>(d: D) -> Result<Self, D::Error> { Deserialize::deserialize(d).map(Self::new) } } pub trait BestSearch { fn is_at_max_depth(&self, depth: Depth) -> bool; fn can_enter_initial_updating_best(&mut self, start_coord: Coord) -> bool; fn can_step_updating_best(&mut self, step: Step) -> bool { self.can_enter_initial_updating_best(step.to_coord) } fn best_coord(&self) -> Option<Coord>; } impl Context { pub fn new(size: Size) -> Self { Self { seen_set: SeenSet::new(size), queue: VecDeque::new(), } } fn consider<B: BestSearch>(&mut self, best_search: &mut B, step: Step, depth: Depth) { if let Some(Visit) = self.seen_set.try_visit_step(step, depth) { if best_search.can_step_updating_best(step) { if !best_search.is_at_max_depth(depth) { self.queue.push_back(Node { step, depth }); } } } } fn best_search_core<B: BestSearch>(&mut self, best_search: &mut B, start: Coord) { self.seen_set.init(start); self.queue.clear(); if !best_search.can_enter_initial_updating_best(start) { return; } if best_search.is_at_max_depth(0) { return; } for &in_direction in &UNIT_COORDS { let step = Step { to_coord: start + in_direction.to_coord(), in_direction, }; self.consider(best_search, step, 1); } if best_search.is_at_max_depth(1) { return; } while let Some(Node { step, depth }) = self.queue.pop_front() { let next_depth = depth + 1; self.consider(best_search, step.forward(), next_depth); self.consider(best_search, step.left(), next_depth); self.consider(best_search, step.right(), next_depth); } } pub fn best_search_path<B: BestSearch>(&mut self, mut best_search: B, start: Coord, path: &mut Path) { self.best_search_core(&mut best_search, start); let end = best_search.best_coord().unwrap_or(start); self.seen_set.build_path_to(end, path); } pub fn best_search_first<B: BestSearch>(&mut self, mut best_search: B, start: Coord) -> Option<CardinalDirection> { self.best_search_core(&mut best_search, start); let end = best_search.best_coord().unwrap_or(start); self.seen_set.first_direction_towards(end) } } #[cfg(test)] mod test { use super::*; use grid_2d::Grid; use rand::{Rng, SeedableRng}; use rand_isaac::Isaac64Rng; #[derive(Clone)] enum Cell { Solid, Traversable(u8), } struct Test { grid: Grid<Cell>, start: Coord, } fn str_slice_to_test(str_slice: &[&str]) -> Test { let width = str_slice[0].len() as u32; let height = str_slice.len() as u32; let size = Size::new(width, height); let mut grid = Grid::new_clone(size, Cell::Solid); let mut start = None; for (y, line) in str_slice.iter().enumerate() { for (x, ch) in line.chars().enumerate() { let coord = Coord::new(x as i32, y as i32); let cell = match ch { '.' => Cell::Traversable(0), '@' => { start = Some(coord); Cell::Traversable(0) } '1' => Cell::Traversable(1), '2' => Cell::Traversable(2), '#' => Cell::Solid, _ => panic!(), }; *grid.get_checked_mut(coord) = cell; } } Test { grid, start: start.unwrap(), } } fn random_test<R: Rng>(size: Size, rng: &mut R) -> Test { let mut grid = Grid::new_fn(size, |_| { let score = rng.gen(); Cell::Traversable(score) }); let num_solid = size.count() / 4; for _ in 0..num_solid { let coord = Coord::random_within(size, rng); *grid.get_checked_mut(coord) = Cell::Solid; } let start = Coord::new(0, 0); Test { grid, start } } fn str_slice_to_test_start_score(str_slice: &[&str], start_score: u8) -> Test { let mut test = str_slice_to_test(str_slice); *test.grid.get_checked_mut(test.start) = Cell::Traversable(start_score); test } struct ConstrainedSearch<'a> { max_depth: Depth, world: &'a Grid<Cell>, best_coord: Option<Coord>, best_score: u8, } impl<'a> ConstrainedSearch<'a> { fn new(max_depth: Depth, world: &'a Grid<Cell>) -> Self { Self { max_depth, world, best_coord: None, best_score: 0, } } } impl<'a> BestSearch for ConstrainedSearch<'a> { fn is_at_max_depth(&self, depth: Depth) -> bool { depth >= self.max_depth } fn can_enter_initial_updating_best(&mut self, coord: Coord) -> bool { if let Some(&Cell::Traversable(score)) = self.world.get(coord) { if self.best_coord.is_none() || score > self.best_score { self.best_score = score; self.best_coord = Some(coord); } true } else { false } } fn best_coord(&self) -> Option<Coord> { self.best_coord } } const GRID_A: &[&str] = &[ "..........", ".1.....2..", "..........", "..........", "..........", "..........", "...1......", "..........", ".@........", "..........", ]; #[test] fn grid_a() { let Test { grid, start } = str_slice_to_test(GRID_A); let mut ctx = Context::new(grid.size()); let mut path = Path::default(); ctx.best_search_path(ConstrainedSearch::new(100, &grid), start, &mut path); assert_eq!(path.len(), 13); ctx.best_search_path(ConstrainedSearch::new(10, &grid), start, &mut path); assert_eq!(path.len(), 4); ctx.best_search_path(ConstrainedSearch::new(3, &grid), start, &mut path); assert_eq!(path.len(), 0); } const GRID_B: &[&str] = &[ "....#.....", ".@........", "....#.....", "########.#", "1......#.#", ".....#...#", "..########", "...#2.....", "##.###....", "..........", ]; #[test] fn grid_b() { let Test { grid, start } = str_slice_to_test(GRID_B); let mut ctx = Context::new(grid.size()); let mut path = Path::default(); ctx.best_search_path(ConstrainedSearch::new(100, &grid), start, &mut path); assert_eq!(path.len(), 33); ctx.best_search_path(ConstrainedSearch::new(30, &grid), start, &mut path); assert_eq!(path.len(), 20); ctx.best_search_path(ConstrainedSearch::new(3, &grid), start, &mut path); assert_eq!(path.len(), 0); } const GRID_C: &[&str] = &[ "..........", "..........", "..........", "..........", "..........", "..........", ".1........", "..........", ".@2.......", "..........", ]; #[test] fn grid_c() { let Test { grid, start } = str_slice_to_test(GRID_C); let mut ctx = Context::new(grid.size()); let mut path = Path::default(); ctx.best_search_path(ConstrainedSearch::new(100, &grid), start, &mut path); assert_eq!(path.len(), 1); ctx.best_search_path(ConstrainedSearch::new(2, &grid), start, &mut path); assert_eq!(path.len(), 1); ctx.best_search_path(ConstrainedSearch::new(0, &grid), start, &mut path); assert_eq!(path.len(), 0); } const GRID_D: &[&str] = &[ "..........", "..........", "..........", "..........", "..........", "..........", "..........", "..........", ".@........", "..........", ]; #[test] fn grid_d() { let Test { grid, start } = str_slice_to_test_start_score(GRID_D, 10); let mut ctx = Context::new(grid.size()); let mut path = Path::default(); ctx.best_search_path(ConstrainedSearch::new(100, &grid), start, &mut path); assert_eq!(path.len(), 0); ctx.best_search_path(ConstrainedSearch::new(2, &grid), start, &mut path); assert_eq!(path.len(), 0); ctx.best_search_path(ConstrainedSearch::new(0, &grid), start, &mut path); assert_eq!(path.len(), 0); } #[test] fn grid_random() { let mut rng = Isaac64Rng::seed_from_u64(0); let num_tests = 1000; let size = Size::new(10, 10); let mut ctx = Context::new(size); let mut path = Path::default(); for _ in 0..num_tests { let Test { grid, start } = random_test(size, &mut rng); ctx.best_search_path(ConstrainedSearch::new(100, &grid), start, &mut path); } } }