world/de: new module for deserialization data structures

The new structures contain only the fields that MinedMap needs.

src/lib.rs

@@ -1,2 +1,3 @@
 pub mod io;
 pub mod types;
+pub mod world;

src/main.rs

@@ -1,3 +1,20 @@
-fn main() {
-	println!("Hello, world!");
+use std::path::PathBuf;
+
+use anyhow::Result;
+use clap::Parser;
+
+#[derive(Debug, Parser)]
+struct Args {
+	/// Filename to dump
+	file: PathBuf,
+}
+
+fn main() -> Result<()> {
+	let args = Args::parse();
+
+	minedmap::io::region::from_file(args.file.as_path())?.foreach_chunk(
+		|coords, value: minedmap::world::de::Chunk| {
+			println!("Chunk {:?}: {:#?}", coords, value);
+		},
+	)
 }

src/world/de.rs

@@ -0,0 +1,101 @@
+//! Data structures used to deserialize Minecraft save data
+
+use serde::Deserialize;
+
+/// Element of the `palette` list of 1.18+ [block states](BlockStatesV1_18)
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "PascalCase")]
+pub struct BlockStatePaletteEntry {
+	pub name: String,
+}
+
+/// 1.18+ `block_states` element found in a [section](SectionV1_18)
+#[derive(Debug, Deserialize)]
+pub struct BlockStatesV1_18 {
+	pub palette: Vec<BlockStatePaletteEntry>,
+	pub data: Option<fastnbt::LongArray>,
+}
+
+/// 1.18+ `biomes` element found in a [section](SectionV1_18)
+#[derive(Debug, Deserialize)]
+pub struct BiomesV1_18 {
+	pub palette: Vec<String>,
+	pub data: Option<fastnbt::LongArray>,
+}
+
+/// Element of the 1.18+ `sections` list found in a [Chunk]
+#[derive(Debug, Deserialize)]
+pub struct SectionV1_18 {
+	#[serde(rename = "Y")]
+	pub y: i32,
+	pub block_states: BlockStatesV1_18,
+	pub biomes: BiomesV1_18,
+	#[serde(rename = "BlockLight")]
+	pub block_light: Option<fastnbt::ByteArray>,
+}
+
+/// Version-specific part of a pre-1.18 [Section](SectionOld)
+#[derive(Debug, Deserialize)]
+#[serde(untagged)]
+pub enum SectionOldVariants {
+	#[serde(rename_all = "PascalCase")]
+	V1_13 {
+		block_states: fastnbt::LongArray,
+		palette: Vec<BlockStatePaletteEntry>,
+	},
+	#[serde(rename_all = "PascalCase")]
+	Old {
+		blocks: fastnbt::ByteArray,
+		data: fastnbt::ByteArray,
+	},
+	Empty {},
+}
+
+/// Pre-1.18 section element found in the [Level](LevelOld) compound
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "PascalCase")]
+pub struct SectionOld {
+	pub y: i8,
+	pub block_light: Option<fastnbt::ByteArray>,
+	#[serde(flatten)]
+	pub section: SectionOldVariants,
+}
+
+/// Pre-1.18 biome fields found in the [Level](LevelOld) compound
+#[derive(Debug, Deserialize)]
+#[serde(untagged)]
+pub enum BiomesOld {
+	IntArray(fastnbt::IntArray),
+	ByteArray(fastnbt::ByteArray),
+}
+
+/// `Level` compound element found in pre-1.18 [chunks](Chunk)
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "PascalCase")]
+pub struct LevelOld {
+	#[serde(default)]
+	pub sections: Vec<SectionOld>,
+	pub biomes: Option<BiomesOld>,
+}
+
+/// Version-specific part of a [Chunk] compound
+#[derive(Debug, Deserialize)]
+#[serde(untagged)]
+pub enum ChunkVariants {
+	V1_18 {
+		sections: Vec<SectionV1_18>,
+	},
+	#[serde(rename_all = "PascalCase")]
+	Old {
+		level: LevelOld,
+	},
+}
+
+/// Toplevel compound element of a Minecraft chunk
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "PascalCase")]
+pub struct Chunk {
+	pub data_version: Option<u32>,
+	#[serde(flatten)]
+	pub chunk: ChunkVariants,
+}

src/world/mod.rs

@@ -0,0 +1 @@
+pub mod de;