Rewriting with zero dependencies

.gitignore

@@ -1,2 +1,3 @@
 /target
 Cargo.lock
+.vscode

Cargo.toml

@@ -1,9 +1,8 @@
 [package]
 name = "blotter"
 version = "0.1.0"
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
-[dependencies]
-declio = "0.2.0"
+[dependencies]

examples/load.rs

@@ -0,0 +1,16 @@
+use std::{env::args_os, fs::File, io::BufReader, process::exit};
+
+use blotter::BlotterFile;
+
+fn main() -> Result<(), blotter::Error> {
+    let infile = args_os().nth(1).unwrap_or_else(usage);
+    let mut reader = BufReader::new(File::open(infile)?);
+    let blotter_file = BlotterFile::read(&mut reader)?;
+    println!("{:#?}", blotter_file);
+    Ok(())
+}
+
+fn usage<T>() -> T {
+    eprintln!("missing argument: input file name");
+    exit(1);
+}

src/lib.rs

@@ -1,131 +1,357 @@
-use declio::ctx::Len;
-use declio::util::{magic_bytes, zero_one, LittleEndian};
-use declio::{Decode, Encode};
-use std::convert::TryInto;
-
-type ComponentId = LittleEndian<u16>;
-type ComponentAddress = LittleEndian<u32>;
-type Int = LittleEndian<i32>;
-type Float = LittleEndian<f32>;
-type Version = [Int; 4];
-
-#[derive(Debug, Clone, Copy, PartialEq, Encode, Decode)]
-#[declio(id_type = "u8")]
-enum SaveType {
-    #[declio(id = "1")]
+#[derive(Debug, Clone, Copy, PartialEq)]
+#[non_exhaustive]
+pub enum SaveType {
     World,
-    #[declio(id = "2")]
     Subassembly,
 }
 
-#[derive(Debug, Encode, Decode)]
-pub struct BlotterFile {
-    header: Header,
-    save_version: u8,
-    game_version: Version,
-    save_type: SaveType,
-    components_len: Int,
-    wires_len: Int,
-    mods_len: Int,
-    #[declio(ctx = "Len(mods_len.0.try_into()?)")]
-    mods: Vec<Mod>,
-    component_ids_len: Int,
-    #[declio(ctx = "Len(component_ids_len.0.try_into()?)")]
-    component_ids: Vec<ComponentIdMapping>,
-    #[declio(ctx = "Len(components_len.0.try_into()?)")]
-    components: Vec<Component>,
-    #[declio(ctx = "Len(wires_len.0.try_into()?)")]
-    wires: Vec<Wire>,
-    #[declio(ctx = "*save_type")]
-    circuit_states: CircuitStates,
-    footer: Footer,
+#[derive(Debug)]
+struct ModInfo {
+    mod_id: String,
+    mod_version: [i32; 4],
 }
 
-magic_bytes! {
-    #[derive(Debug)]
-    Header(b"Logic World save");
-
-    #[derive(Debug)]
-    Footer(b"redstone sux lol");
+#[derive(Debug)]
+struct ComponentType {
+    numeric_id: u16,
+    text_id: String,
 }
 
-#[derive(Debug, Encode, Decode)]
-struct Text {
-    len: Int,
-    #[declio(with = "declio::util::utf8", ctx = "Len(len.0.try_into()?)")]
-    value: String,
-}
-
-#[derive(Debug, Encode, Decode)]
-struct Mod {
-    mod_id: Text,
-    version: Version,
-}
-
-#[derive(Debug, Encode, Decode)]
-struct ComponentIdMapping {
-    numeric_id: ComponentId,
-    text_id: Text,
-}
-
-#[derive(Debug, Encode, Decode)]
+#[derive(Debug)]
 struct Input {
-    circuit_state_id: Int,
+    circuit_state_id: i32,
 }
 
-#[derive(Debug, Encode, Decode)]
+#[derive(Debug)]
 struct Output {
-    circuit_state_id: Int,
+    circuit_state_id: i32,
 }
 
-#[derive(Debug, Encode, Decode)]
+#[derive(Debug)]
 struct Component {
-    address: ComponentAddress,
-    parent: ComponentAddress,
-    type_id: ComponentId,
-    position: [Float; 3],
-    rotation: [Float; 4],
-    inputs_len: Int,
-    #[declio(ctx = "Len(inputs_len.0.try_into()?)")]
+    address: u32,
+    parent: u32,
+    type_id: u16,
+    position: [f32; 3],
+    rotation: [f32; 4],
     inputs: Vec<Input>,
-    outputs_len: Int,
-    #[declio(ctx = "Len(outputs_len.0.try_into()?)")]
     outputs: Vec<Output>,
-    custom_data_len: Int,
-    #[declio(skip_if = "custom_data_len.0 == -1")]
-    #[declio(ctx = "Len(custom_data_len.0.try_into()?)")]
     custom_data: Option<Vec<u8>>,
 }
 
-#[derive(Debug, Encode, Decode)]
+#[derive(Debug)]
 struct PegAddress {
-    #[declio(with = "zero_one")]
     is_input: bool,
-    component: ComponentAddress,
-    index: Int,
+    component_address: u32,
+    peg_index: i32,
 }
 
-#[derive(Debug, Encode, Decode)]
+#[derive(Debug)]
 struct Wire {
-    peg_1: PegAddress,
-    peg_2: PegAddress,
-    circuit_state_id: Int,
-    rotation: Float,
+    start_peg: PegAddress,
+    end_peg: PegAddress,
+    circuit_state_id: i32,
+    rotation: f32,
 }
 
-#[derive(Debug, Encode, Decode)]
-#[declio(ctx = "save_type: SaveType", id_expr = "save_type")]
+#[derive(Debug)]
 enum CircuitStates {
-    #[declio(id = "SaveType::World")]
-    WorldFormat {
-        len: Int,
-        #[declio(ctx = "Len(len.0.try_into()?)")]
-        circuit_states: Vec<u8>,
-    },
-    #[declio(id = "SaveType::Subassembly")]
-    SubassemblyFormat {
-        len: Int,
-        #[declio(ctx = "Len(len.0.try_into()?)")]
-        on_states: Vec<Int>,
-    },
+    WorldFormat { circuit_states: Vec<u8> },
+    SubassemblyFormat { on_states: Vec<i32> },
+}
+
+#[derive(Debug)]
+pub struct BlotterFile {
+    game_version: [i32; 4],
+    save_type: SaveType,
+    mods: Vec<ModInfo>,
+    component_types: Vec<ComponentType>,
+    components: Vec<Component>,
+    wires: Vec<Wire>,
+    circuit_states: CircuitStates,
+}
+
+impl BlotterFile {
+    pub fn new(game_version: [i32; 4]) -> Self {
+        Self {
+            game_version,
+            save_type: SaveType::World,
+            mods: Vec::new(),
+            component_types: Vec::new(),
+            components: Vec::new(),
+            wires: Vec::new(),
+            circuit_states: CircuitStates::WorldFormat {
+                circuit_states: Vec::new(),
+            },
+        }
+    }
+
+    pub fn read<R>(reader: &mut R) -> Result<Self, Error>
+    where
+        R: std::io::Read,
+    {
+        read_magic(reader, b"Logic World save")?;
+
+        let save_version = read_u8(reader)?;
+        if save_version != 5 {
+            return Err(Error::IncompatibleVersion(save_version));
+        }
+
+        let game_version = read_version(reader)?;
+
+        let save_type_id = read_u8(reader)?;
+        let save_type = match save_type_id {
+            1 => SaveType::World,
+            2 => SaveType::Subassembly,
+            _ => {
+                return Err(Error::UnknownSaveType(save_type_id));
+            }
+        };
+
+        let num_components = read_usize(reader)?;
+        let num_wires = read_usize(reader)?;
+
+        let num_mods = read_usize(reader)?;
+        let mods = read_vec(num_mods, || {
+            let mod_id = read_string(reader)?;
+            let mod_version = read_version(reader)?;
+            Ok(ModInfo {
+                mod_id,
+                mod_version,
+            })
+        })?;
+
+        let num_component_types: usize = read_usize(reader)?;
+        let component_types = read_vec(num_component_types, || {
+            let numeric_id = read_u16(reader)?;
+            let text_id = read_string(reader)?;
+            Ok(ComponentType {
+                numeric_id,
+                text_id,
+            })
+        })?;
+
+        let components = read_vec(num_components, || {
+            let address = read_u32(reader)?;
+            let parent = read_u32(reader)?;
+            let type_id = read_u16(reader)?;
+            let position = read_array(|| read_f32(reader))?;
+            let rotation = read_array(|| read_f32(reader))?;
+
+            let num_inputs = read_usize(reader)?;
+            let inputs = read_vec(num_inputs, || {
+                let circuit_state_id = read_i32(reader)?;
+                Ok(Input { circuit_state_id })
+            })?;
+
+            let num_outputs = read_usize(reader)?;
+            let outputs = read_vec(num_outputs, || {
+                let circuit_state_id = read_i32(reader)?;
+                Ok(Output { circuit_state_id })
+            })?;
+
+            let custom_data_len = read_i32(reader)?;
+            let custom_data = if custom_data_len < 0 {
+                None
+            } else {
+                Some(read_bytevec(reader, custom_data_len as usize)?)
+            };
+
+            Ok(Component {
+                address,
+                parent,
+                type_id,
+                position,
+                rotation,
+                inputs,
+                outputs,
+                custom_data,
+            })
+        })?;
+
+        let wires = read_vec(num_wires, || {
+            let start_peg = read_peg_address(reader)?;
+            let end_peg = read_peg_address(reader)?;
+            let circuit_state_id = read_i32(reader)?;
+            let rotation = read_f32(reader)?;
+
+            Ok(Wire {
+                start_peg,
+                end_peg,
+                circuit_state_id,
+                rotation,
+            })
+        })?;
+
+        let circuit_states = match save_type {
+            SaveType::World => {
+                let num_bytes = read_usize(reader)?;
+                let circuit_states = read_bytevec(reader, num_bytes)?;
+                CircuitStates::WorldFormat { circuit_states }
+            }
+            SaveType::Subassembly => {
+                let num_on_states = read_usize(reader)?;
+                let on_states = read_vec(num_on_states, || read_i32(reader))?;
+                CircuitStates::SubassemblyFormat { on_states }
+            }
+        };
+
+        read_magic(reader, b"redstone sux lol")?;
+
+        Ok(Self {
+            game_version,
+            save_type,
+            mods,
+            component_types,
+            components,
+            wires,
+            circuit_states,
+        })
+    }
+}
+
+#[derive(Debug)]
+#[non_exhaustive]
+pub enum Error {
+    IoError(std::io::Error),
+    InvalidSave,
+    IncompatibleVersion(u8),
+    UnknownSaveType(u8),
+}
+
+impl From<std::io::Error> for Error {
+    fn from(error: std::io::Error) -> Self {
+        Self::IoError(error)
+    }
+}
+
+fn read_u8<R>(reader: &mut R) -> Result<u8, Error>
+where
+    R: std::io::Read,
+{
+    let mut bytes = [0u8; 1];
+    reader.read_exact(&mut bytes)?;
+    Ok(u8::from_le_bytes(bytes))
+}
+
+fn read_u16<R>(reader: &mut R) -> Result<u16, Error>
+where
+    R: std::io::Read,
+{
+    let mut bytes = [0u8; 2];
+    reader.read_exact(&mut bytes)?;
+    Ok(u16::from_le_bytes(bytes))
+}
+
+fn read_i32<R>(reader: &mut R) -> Result<i32, Error>
+where
+    R: std::io::Read,
+{
+    let mut bytes = [0u8; 4];
+    reader.read_exact(&mut bytes)?;
+    Ok(i32::from_le_bytes(bytes))
+}
+
+fn read_u32<R>(reader: &mut R) -> Result<u32, Error>
+where
+    R: std::io::Read,
+{
+    let mut bytes = [0u8; 4];
+    reader.read_exact(&mut bytes)?;
+    Ok(u32::from_le_bytes(bytes))
+}
+
+fn read_f32<R>(reader: &mut R) -> Result<f32, Error>
+where
+    R: std::io::Read,
+{
+    let mut bytes = [0u8; 4];
+    reader.read_exact(&mut bytes)?;
+    Ok(f32::from_le_bytes(bytes))
+}
+
+fn read_usize<R>(reader: &mut R) -> Result<usize, Error>
+where
+    R: std::io::Read,
+{
+    read_i32(reader)?.try_into().map_err(|_| Error::InvalidSave)
+}
+
+fn read_string<R>(reader: &mut R) -> Result<String, Error>
+where
+    R: std::io::Read,
+{
+    let string_len = read_usize(reader)?;
+    let bytes = read_bytevec(reader, string_len)?;
+    String::from_utf8(bytes).map_err(|_| Error::InvalidSave)
+}
+
+fn read_vec<F, T>(len: usize, mut reader: F) -> Result<Vec<T>, Error>
+where
+    F: FnMut() -> Result<T, Error>,
+{
+    let mut vec = Vec::with_capacity(len);
+    for _ in 0..len {
+        vec.push(reader()?);
+    }
+    Ok(vec)
+}
+
+fn read_array<F, T, const LEN: usize>(mut reader: F) -> Result<[T; LEN], Error>
+where
+    F: FnMut() -> Result<T, Error>,
+    T: Default + Copy,
+{
+    let mut arr = [Default::default(); LEN];
+    for slot in &mut arr {
+        *slot = reader()?;
+    }
+    Ok(arr)
+}
+
+fn read_magic<R>(reader: &mut R, magic_bytes: &[u8]) -> Result<(), Error>
+where
+    R: std::io::Read,
+{
+    let mut header = [0u8; 16];
+    reader.read_exact(&mut header)?;
+    if header != *magic_bytes {
+        return Err(Error::InvalidSave);
+    }
+    Ok(())
+}
+
+fn read_version<R>(reader: &mut R) -> Result<[i32; 4], Error>
+where
+    R: std::io::Read,
+{
+    read_array(|| read_i32(reader))
+}
+
+fn read_bytevec<R>(reader: &mut R, len: usize) -> Result<Vec<u8>, Error>
+where
+    R: std::io::Read,
+{
+    let mut vec = vec![0u8; len];
+    reader.read_exact(&mut vec)?;
+    Ok(vec)
+}
+
+fn read_peg_address<R>(reader: &mut R) -> Result<PegAddress, Error>
+where
+    R: std::io::Read,
+{
+    let peg_kind = read_u8(reader)?;
+    let is_input = match peg_kind {
+        0 => false,
+        1 => true,
+        _ => return Err(Error::InvalidSave),
+    };
+    let component_address = read_u32(reader)?;
+    let peg_index = read_i32(reader)?;
+    Ok(PegAddress {
+        is_input,
+        component_address,
+        peg_index,
+    })
 }