Allow converting generated levels to entities

Add a new Wall entity, and allow converting generated levels to entity
maps containing them, then finally displaying them using some of
the (now expanded) box drawing machinery.

1 files changed, 34 insertions, 0 deletions

diff --git a/src/entities/environment.rs b/src/entities/environment.rs
new file mode 100644
index 000000000000..64366a505496
--- /dev/null
+++ b/src/entities/environment.rs
@@ -0,0 +1,34 @@
+use crate::display;
+use crate::display::draw_box::{BoxStyle, Stylable};
+use crate::entities::Entity;
+use crate::types::{Neighbors, Position};
+use std::io::{self, Write};
+
+entity! {
+    pub struct Wall {
+        pub style: BoxStyle
+    }
+}
+
+impl Wall {
+    pub fn new(position: Position, style: BoxStyle) -> Self {
+        new_entity!(Wall { position, style })
+    }
+}
+
+impl display::DrawWithNeighbors for Wall {
+    fn do_draw_with_neighbors<'a, 'b>(
+        &'a self,
+        out: &'b mut Write,
+        neighbors: &'a Neighbors<Vec<&'a Box<dyn Entity>>>,
+    ) -> io::Result<()> {
+        let neighbor_styles: Neighbors<Option<BoxStyle>> =
+            neighbors.map(|es| {
+                es.iter()
+                    .filter_map(|e| e.downcast_ref::<Wall>())
+                    .map(|wall| wall.style)
+                    .next()
+            });
+        write!(out, "{}", neighbor_styles.style(self.style))
+    }
+}