types: introduce LayerBlockArray

A LayerBlockArray is a generic array of data stored for each block of a
chunk layer. It provides the same methods as a ChunkArray.

src/types.rs

@@ -52,6 +52,40 @@ impl Debug for LayerBlockCoords {
 	}
 }
 
+/// Generic array for data stored per block of a chunk layer
+///
+/// Includes various convenient iteration functions.
+#[derive(Debug, Clone, Copy, Default)]
+pub struct LayerBlockArray<T>(pub [[T; BLOCKS_PER_CHUNK]; BLOCKS_PER_CHUNK]);
+
+impl<T> LayerBlockArray<T> {
+	pub fn keys() -> impl Iterator<Item = LayerBlockCoords> + Clone + Debug {
+		iproduct!(BlockZ::iter(), BlockX::iter()).map(|(z, x)| LayerBlockCoords { x, z })
+	}
+
+	pub fn values(&self) -> impl Iterator<Item = &T> + Clone + Debug {
+		Self::keys().map(|k| &self[k])
+	}
+
+	pub fn iter(&self) -> impl Iterator<Item = (LayerBlockCoords, &T)> + Clone + Debug {
+		Self::keys().map(|k| (k, &self[k]))
+	}
+}
+
+impl<T> Index<LayerBlockCoords> for LayerBlockArray<T> {
+	type Output = T;
+
+	fn index(&self, index: LayerBlockCoords) -> &Self::Output {
+		&self.0[index.z.0 as usize][index.x.0 as usize]
+	}
+}
+
+impl<T> IndexMut<LayerBlockCoords> for LayerBlockArray<T> {
+	fn index_mut(&mut self, index: LayerBlockCoords) -> &mut Self::Output {
+		&mut self.0[index.z.0 as usize][index.x.0 as usize]
+	}
+}
+
 /// X, Y and Z coordinates of a block in a chunk section
 #[derive(Clone, Copy, PartialEq, Eq)]
 pub struct SectionBlockCoords {