world: introduce SectionIterItem struct

src/world/chunk.rs

@@ -182,16 +182,19 @@ impl<'a> Chunk<'a> {
 	}
 }
 
+#[derive(Debug, Clone, Copy)]
+pub struct SectionIterItem<'a> {
+	pub y: SectionY,
+	pub section: &'a dyn Section,
+}
+
 trait SectionIterTrait<'a>:
-	Iterator<Item = (SectionY, &'a dyn Section)>
+	Iterator<Item = SectionIterItem<'a>> + DoubleEndedIterator + ExactSizeIterator + FusedIterator
-	+ DoubleEndedIterator
-	+ ExactSizeIterator
-	+ FusedIterator
 {
 }
 
 impl<'a, T> SectionIterTrait<'a> for T where
-	T: Iterator<Item = (SectionY, &'a dyn Section)>
+	T: Iterator<Item = SectionIterItem<'a>>
 		+ DoubleEndedIterator
 		+ ExactSizeIterator
 		+ FusedIterator
@@ -204,14 +207,15 @@ impl<'a> SectionIter<'a> {
 		F: FnOnce(&mut dyn SectionIterTrait<'a>) -> T,
 	{
 		match &mut self.inner {
-			SectionIterInner::V1_18 { iter } => f(
+			SectionIterInner::V1_18 { iter } => f(&mut iter.map(|(&y, section)| SectionIterItem {
-				&mut iter.map(|(y, section)| -> (SectionY, &'a dyn Section) { (*y, &section.0) })
+				y,
-			),
+				section: &section.0,
+			})),
 			SectionIterInner::V1_13 { iter } => {
-				f(&mut iter.map(|(y, section)| -> (SectionY, &'a dyn Section) { (*y, section) }))
+				f(&mut iter.map(|(&y, section)| SectionIterItem { y, section }))
 			}
 			SectionIterInner::V0 { iter } => {
-				f(&mut iter.map(|(y, section)| -> (SectionY, &'a dyn Section) { (*y, section) }))
+				f(&mut iter.map(|(&y, section)| SectionIterItem { y, section }))
 			}
 			SectionIterInner::Empty => f(&mut iter::empty()),
 		}
@@ -219,7 +223,7 @@ impl<'a> SectionIter<'a> {
 }
 
 impl<'a> Iterator for SectionIter<'a> {
-	type Item = (SectionY, &'a dyn Section);
+	type Item = SectionIterItem<'a>;
 
 	fn next(&mut self) -> Option<Self::Item> {
 		self.with_iter(|iter| iter.next())

src/world/layer.rs

@@ -1,7 +1,7 @@
 use anyhow::{Context, Result};
 use serde::{Deserialize, Serialize};
 
-use super::chunk::Chunk;
+use super::chunk::{Chunk, SectionIterItem};
 use crate::{
 	resource::{BlockFlag, BlockType},
 	types::*,
@@ -97,7 +97,11 @@ pub fn top_layer(chunk: &Chunk) -> Result<Box<BlockInfoArray>> {
 	let mut done = 0;
 	let mut ret = Box::<BlockInfoArray>::default();
 
-	for (section_y, section) in chunk.sections().rev() {
+	for SectionIterItem {
+		y: section_y,
+		section,
+	} in chunk.sections().rev()
+	{
 		for y in BlockY::iter().rev() {
 			for xz in BlockInfoArray::keys() {
 				let entry = &mut ret[xz];

src/world/section.rs

@@ -1,3 +1,5 @@
+use std::fmt::Debug;
+
 use anyhow::{bail, Context, Result};
 use num_integer::div_rem;
 
@@ -26,7 +28,7 @@ fn palette_bits(len: usize, min: u8, max: u8) -> Option<u8> {
 }
 
 /// Trait for common functions of [SectionV1_13] and [SectionV0]
-pub trait Section {
+pub trait Section: Debug {
 	fn block_at(&self, coords: SectionBlockCoords) -> Result<Option<BlockType>>;
 }