Refactor simple map builder to use the Rust builder pattern

src/main.rs

@@ -1,4 +1,4 @@
-use rltk::{GameState, Point, Rltk};
+use rltk::{GameState, Point, RandomNumberGenerator, Rltk};
 use specs::prelude::*;
 use specs::saveload::{SimpleMarker, SimpleMarkerAllocator};
 
@@ -461,15 +461,19 @@ impl State {
         self.mapgen_timer = 0.0;
         self.mapgen_history.clear();
 
-        let mut builder = map_builders::random_builder(new_depth);
-        builder.build_map();
+        let mut rng = self.ecs.write_resource::<RandomNumberGenerator>();
+        let mut builder = map_builders::random_builder(new_depth, &mut rng);
+        builder.build_map(&mut rng);
+
+        std::mem::drop(rng);
+
         self.mapgen_history = builder.get_snapshot_history();
 
         let player_start;
         {
             let mut worldmap_resource = self.ecs.write_resource::<Map>();
             *worldmap_resource = builder.get_map();
-            player_start = builder.get_starting_position();
+            player_start = builder.get_starting_position().as_mut().unwrap().clone();
         }
 
         // Spawn bad guys

src/map_builders.rs

@@ -6,10 +6,15 @@ mod dla;
 mod drunkard;
 mod maze;
 mod prefab_builder;
+mod room_based_spawner;
+mod room_based_stairs;
+mod room_based_starting_position;
 mod simple_map;
 mod voronoi;
 mod waveform_collapse;
 
+use crate::{spawner, Map, Position, Rect, SHOW_MAPGEN_VISUALIZER};
+use ::rltk::RandomNumberGenerator;
 use bsp_dungeon::BspDungeonBuilder;
 use bsp_interior::BspInteriorBuilder;
 use cellular_automata::CellularAutomataBuilder;
@@ -18,12 +23,119 @@ use dla::DLABuilder;
 use drunkard::DrunkardsWalkBuilder;
 use maze::MazeBuilder;
 use prefab_builder::PrefabBuilder;
+use room_based_spawner::RoomBasedSpawner;
+use room_based_stairs::RoomBasedStairs;
+use room_based_starting_position::RoomBasedStartingPosition;
 use simple_map::SimpleMapBuilder;
 use specs::prelude::*;
 use voronoi::VoronoiCellBuilder;
 use waveform_collapse::WaveformCollapseBuilder;
 
-use crate::{spawner, Map, Position};
+pub struct BuilderMap {
+    pub spawn_list: Vec<(usize, String)>,
+    pub map: Map,
+    pub starting_position: Option<Position>,
+    pub rooms: Option<Vec<Rect>>,
+    pub history: Vec<Map>,
+}
+
+impl BuilderMap {
+    fn take_snapshot(&mut self) {
+        if SHOW_MAPGEN_VISUALIZER {
+            let mut snapshot = self.map.clone();
+            for v in snapshot.revealed_tiles.iter_mut() {
+                *v = true;
+            }
+            self.history.push(snapshot);
+        }
+    }
+}
+
+pub struct BuilderChain {
+    starter: Option<Box<dyn InitialMapBuilder>>,
+    builders: Vec<Box<dyn MetaMapBuilder>>,
+    pub build_data: BuilderMap,
+}
+
+impl BuilderChain {
+    pub fn new(new_depth: i32) -> BuilderChain {
+        BuilderChain {
+            starter: None,
+            builders: Vec::new(),
+            build_data: BuilderMap {
+                spawn_list: Vec::new(),
+                map: Map::new(new_depth),
+                starting_position: None,
+                rooms: None,
+                history: Vec::new(),
+            },
+        }
+    }
+
+    pub fn start_with(&mut self, starter: Box<dyn InitialMapBuilder>) -> &mut Self {
+        match self.starter {
+            None => self.starter = Some(starter),
+            Some(_) => panic!("You can only have one starting builder."),
+        }
+
+        self
+    }
+
+    pub fn with(&mut self, metabuilder: Box<dyn MetaMapBuilder>) -> &mut Self {
+        self.builders.push(metabuilder);
+
+        self
+    }
+
+    pub fn build_map(&mut self, rng: &mut RandomNumberGenerator) -> &mut Self {
+        match &mut self.starter {
+            None => panic!("Cannot run a map builder chain without starting a build system"),
+            Some(starter) => {
+                // Build the starting map
+                starter.build_map(rng, &mut self.build_data);
+            }
+        }
+
+        // Build additional layers in turn
+        for metabuilder in self.builders.iter_mut() {
+            metabuilder.build_map(rng, &mut self.build_data);
+        }
+
+        self
+    }
+
+    pub fn spawn_entities(&mut self, ecs: &mut World) -> &mut Self {
+        for entity in self.build_data.spawn_list.iter() {
+            spawner::spawn_entity(ecs, &(&entity.0, &entity.1));
+        }
+
+        self
+    }
+
+    pub fn get_map(&self) -> Map {
+        self.build_data.map.clone()
+    }
+
+    pub fn get_starting_position(&self) -> Option<Position> {
+        self.build_data.starting_position
+    }
+
+    pub fn get_snapshot_history(&self) -> Vec<Map> {
+        self.build_data.history.clone()
+    }
+
+    pub fn get_spawn_list(&self) -> &Vec<(usize, String)> {
+        &self.build_data.spawn_list
+    }
+}
+
+pub trait InitialMapBuilder {
+    fn build_map(&mut self, rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap);
+}
+
+pub trait MetaMapBuilder {
+    fn build_map(&mut self, rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap);
+}
 
 pub trait MapBuilder {
     fn get_map(&self) -> Map;
@@ -40,44 +152,13 @@ pub trait MapBuilder {
     }
 }
 
-pub fn random_builder(new_depth: i32) -> Box<dyn MapBuilder> {
-    let mut rng = rltk::RandomNumberGenerator::new();
-    let mut result: Box<dyn MapBuilder> = match rng.roll_dice(1, 17) {
-        1 => Box::new(BspDungeonBuilder::new(new_depth)),
-        2 => Box::new(BspInteriorBuilder::new(new_depth)),
-        3 => Box::new(CellularAutomataBuilder::new(new_depth)),
-        4 => Box::new(DrunkardsWalkBuilder::open_area(new_depth)),
-        5 => Box::new(DrunkardsWalkBuilder::open_halls(new_depth)),
-        6 => Box::new(DrunkardsWalkBuilder::winding_passages(new_depth)),
-        7 => Box::new(DrunkardsWalkBuilder::fat_passages(new_depth)),
-        8 => Box::new(DrunkardsWalkBuilder::fearful_symmetry(new_depth)),
-        9 => Box::new(MazeBuilder::new(new_depth)),
-        10 => Box::new(DLABuilder::walk_inwards(new_depth)),
-        11 => Box::new(DLABuilder::walk_outwards(new_depth)),
-        12 => Box::new(DLABuilder::central_attractor(new_depth)),
-        13 => Box::new(DLABuilder::insectoid(new_depth)),
-        14 => Box::new(VoronoiCellBuilder::pythagoras(new_depth)),
-        15 => Box::new(VoronoiCellBuilder::manhattan(new_depth)),
-        16 => Box::new(PrefabBuilder::constant(
-            new_depth,
-            prefab_builder::prefab_levels::WFC_POPULATED,
-        )),
-        _ => Box::new(SimpleMapBuilder::new(new_depth)),
-    };
+pub fn random_builder(new_depth: i32, rng: &mut RandomNumberGenerator) -> BuilderChain {
+    let mut builder = BuilderChain::new(new_depth);
+    builder
+        .start_with(SimpleMapBuilder::new())
+        .with(RoomBasedSpawner::new())
+        .with(RoomBasedStartingPosition::new())
+        .with(RoomBasedStairs::new());
 
-    if rng.roll_dice(1, 3) == 1 {
-        result = Box::new(WaveformCollapseBuilder::derived_map(new_depth, result));
-    }
-
-    if rng.roll_dice(1, 20) == 1 {
-        result = Box::new(PrefabBuilder::sectional(
-            new_depth,
-            prefab_builder::prefab_sections::UNDERGROUND_FORT,
-            result,
-        ));
-    }
-
-    result = Box::new(PrefabBuilder::vaults(new_depth, result));
-
-    result
+    builder
 }

src/map_builders/room_based_spawner.rs

@@ -0,0 +1,34 @@
+use rltk::RandomNumberGenerator;
+
+use crate::map_builders::{spawner, BuilderMap, MetaMapBuilder};
+
+pub struct RoomBasedSpawner {}
+
+impl MetaMapBuilder for RoomBasedSpawner {
+    fn build_map(&mut self, rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
+        self.build(rng, build_data);
+    }
+}
+
+impl RoomBasedSpawner {
+    #[allow(dead_code)]
+    pub fn new() -> Box<RoomBasedSpawner> {
+        Box::new(RoomBasedSpawner {})
+    }
+
+    fn build(&mut self, rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
+        if let Some(rooms) = &build_data.rooms {
+            for room in rooms.iter().skip(1) {
+                spawner::spawn_room(
+                    &build_data.map,
+                    rng,
+                    room,
+                    build_data.map.depth,
+                    &mut build_data.spawn_list,
+                );
+            }
+        } else {
+            panic!("Room Based Spawning only works after rooms have been created.");
+        }
+    }
+}

src/map_builders/room_based_stairs.rs

@@ -0,0 +1,30 @@
+use rltk::RandomNumberGenerator;
+
+use crate::map_builders::{BuilderMap, MetaMapBuilder};
+use crate::TileType;
+
+pub struct RoomBasedStairs {}
+
+impl MetaMapBuilder for RoomBasedStairs {
+    fn build_map(&mut self, rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
+        self.build(rng, build_data);
+    }
+}
+
+impl RoomBasedStairs {
+    #[allow(dead_code)]
+    pub fn new() -> Box<RoomBasedStairs> {
+        Box::new(RoomBasedStairs {})
+    }
+
+    fn build(&mut self, _rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
+        if let Some(rooms) = &build_data.rooms {
+            let stairs_position = rooms[rooms.len() - 1].center();
+            let stairs_idx = build_data.map.xy_idx(stairs_position.0, stairs_position.1);
+            build_data.map.tiles[stairs_idx] = TileType::DownStairs;
+            build_data.take_snapshot();
+        } else {
+            panic!("Room Based Stairs only works after rooms have been created");
+        }
+    }
+}

src/map_builders/room_based_starting_position.rs

@@ -0,0 +1,31 @@
+use rltk::RandomNumberGenerator;
+
+use crate::map_builders::{BuilderMap, MetaMapBuilder};
+use crate::Position;
+
+pub struct RoomBasedStartingPosition {}
+
+impl MetaMapBuilder for RoomBasedStartingPosition {
+    fn build_map(&mut self, rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
+        self.build(rng, build_data);
+    }
+}
+
+impl RoomBasedStartingPosition {
+    #[allow(dead_code)]
+    pub fn new() -> Box<RoomBasedStartingPosition> {
+        Box::new(RoomBasedStartingPosition {})
+    }
+
+    fn build(&mut self, _rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
+        if let Some(rooms) = &build_data.rooms {
+            let start_pos = rooms[0].center();
+            build_data.starting_position = Some(Position {
+                x: start_pos.0,
+                y: start_pos.1,
+            });
+        } else {
+            panic!("Room Based Starting Position only works after rooms have been created.");
+        }
+    }
+}

src/map_builders/simple_map.rs

@@ -1,113 +1,73 @@
 use rltk::RandomNumberGenerator;
 
-use super::{apply_horizontal_tunnel, apply_room_to_map, apply_vertical_tunnel, MapBuilder};
+use crate::map_builders::common::{
+    apply_horizontal_tunnel, apply_room_to_map, apply_vertical_tunnel,
+};
+use crate::map_builders::{BuilderMap, InitialMapBuilder};
 use crate::{spawner, Map, Position, Rect, TileType, SHOW_MAPGEN_VISUALIZER};
 
-pub struct SimpleMapBuilder {
-    map: Map,
-    starting_position: Position,
-    depth: i32,
-    rooms: Vec<Rect>,
-    history: Vec<Map>,
-    spawn_list: Vec<(usize, String)>,
-}
+pub struct SimpleMapBuilder {}
 
-impl MapBuilder for SimpleMapBuilder {
-    fn get_map(&self) -> Map {
-        self.map.clone()
-    }
-
-    fn get_starting_position(&self) -> Position {
-        self.starting_position
-    }
-
-    fn get_snapshot_history(&self) -> Vec<Map> {
-        self.history.clone()
-    }
-
-    fn build_map(&mut self) {
-        self.rooms_and_corridors();
-    }
-
-    fn take_snapshot(&mut self) {
-        if SHOW_MAPGEN_VISUALIZER {
-            let mut snapshot = self.map.clone();
-            for v in snapshot.revealed_tiles.iter_mut() {
-                *v = true;
-            }
-            self.history.push(snapshot);
-        }
-    }
-
-    fn get_spawn_list(&self) -> &Vec<(usize, String)> {
-        &self.spawn_list
+impl InitialMapBuilder for SimpleMapBuilder {
+    #[allow(dead_code)]
+    fn build_map(&mut self, rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
+        self.rooms_and_corridors(rng, build_data);
     }
 }
 
 impl SimpleMapBuilder {
-    pub fn new(new_depth: i32) -> SimpleMapBuilder {
-        SimpleMapBuilder {
-            map: Map::new(new_depth),
-            starting_position: Position { x: 0, y: 0 },
-            depth: new_depth,
-            rooms: Vec::new(),
-            history: Vec::new(),
-            spawn_list: Vec::new(),
-        }
+    #[allow(dead_code)]
+    pub fn new() -> Box<SimpleMapBuilder> {
+        Box::new(SimpleMapBuilder {})
     }
 
-    fn rooms_and_corridors(&mut self) {
+    fn rooms_and_corridors(
+        &mut self,
+        rng: &mut RandomNumberGenerator,
+        build_data: &mut BuilderMap,
+    ) {
         const MAX_ROOMS: i32 = 30;
         const MIN_SIZE: i32 = 6;
         const MAX_SIZE: i32 = 10;
-
-        let mut rng = RandomNumberGenerator::new();
+        let mut rooms: Vec<Rect> = Vec::new();
 
         for _ in 0..MAX_ROOMS {
             let w = rng.range(MIN_SIZE, MAX_SIZE);
             let h = rng.range(MIN_SIZE, MAX_SIZE);
-            let x = rng.roll_dice(1, self.map.width - w - 1) - 1;
-            let y = rng.roll_dice(1, self.map.height - h - 1) - 1;
+            let x = rng.roll_dice(1, build_data.map.width - w - 1) - 1;
+            let y = rng.roll_dice(1, build_data.map.height - h - 1) - 1;
 
             let new_room = Rect::new(x, y, w, h);
             let mut ok = true;
 
-            for other_room in self.rooms.iter() {
+            for other_room in rooms.iter() {
                 if new_room.intersect(other_room) {
                     ok = false;
                 }
             }
 
             if ok {
-                apply_room_to_map(&mut self.map, &new_room);
+                apply_room_to_map(&mut build_data.map, &new_room);
+                build_data.take_snapshot();
 
-                if !self.rooms.is_empty() {
+                if !rooms.is_empty() {
                     let (new_x, new_y) = new_room.center();
-                    let (prev_x, prev_y) = self.rooms[self.rooms.len() - 1].center();
+                    let (prev_x, prev_y) = rooms[rooms.len() - 1].center();
 
                     if rng.range(0, 2) == 1 {
-                        apply_horizontal_tunnel(&mut self.map, prev_x, new_x, prev_y);
-                        apply_vertical_tunnel(&mut self.map, prev_y, new_y, new_x);
+                        apply_horizontal_tunnel(&mut build_data.map, prev_x, new_x, prev_y);
+                        apply_vertical_tunnel(&mut build_data.map, prev_y, new_y, new_x);
                     } else {
-                        apply_vertical_tunnel(&mut self.map, prev_y, new_y, prev_x);
-                        apply_horizontal_tunnel(&mut self.map, prev_x, new_x, new_y);
+                        apply_vertical_tunnel(&mut build_data.map, prev_y, new_y, prev_x);
+                        apply_horizontal_tunnel(&mut build_data.map, prev_x, new_x, new_y);
                     }
                 }
 
-                self.rooms.push(new_room);
-                self.take_snapshot();
+                rooms.push(new_room);
+                build_data.take_snapshot();
             }
         }
 
-        let stairs_position = self.rooms[self.rooms.len() - 1].center();
-        let stairs_idx = self.map.xy_idx(stairs_position.0, stairs_position.1);
-        self.map.tiles[stairs_idx] = TileType::DownStairs;
-
-        self.starting_position = Position::from(self.rooms[0].center());
-
-        // Spawn some entities
-        for room in self.rooms.iter().skip(1) {
-            spawner::spawn_room(&self.map, &mut rng, room, self.depth, &mut self.spawn_list);
-        }
+        build_data.rooms = Some(rooms);
     }
 }