Add methods to read and write from streams

Cargo.toml

@@ -3,7 +3,7 @@ name = "motion_list_rs"
 description = "Library for working with motion_list.bin files in Smash Ultimate"
 repository = "https://github.com/ultimate-research/motion_lib"
 license = "MIT"
-version = "1.4.2"
+version = "1.4.3"
 authors = ["BenHall-7 <[email protected]>"]
 edition = "2021"
 

src/asm.rs

@@ -1,9 +1,9 @@
 use crate::mlist::*;
 use byteorder::{LittleEndian, WriteBytesExt};
 use hash40::*;
-use std::io::{Cursor, Error, ErrorKind};
+use std::io::{Error, ErrorKind, Seek, SeekFrom, Write};
 
-pub fn assemble(cursor: &mut Cursor<Vec<u8>>, mlist: &MList) -> Result<(), Error> {
+pub fn assemble<W: Write + Seek>(cursor: &mut W, mlist: &MList) -> Result<(), Error> {
     cursor.write_hash40::<LittleEndian>(MAGIC)?;
     cursor.write_hash40::<LittleEndian>(mlist.motion_path)?;
     cursor.write_u64::<LittleEndian>(mlist.list.len() as u64)?;
@@ -24,7 +24,7 @@ pub fn assemble(cursor: &mut Cursor<Vec<u8>>, mlist: &MList) -> Result<(), Error
     Ok(())
 }
 
-fn write_motion(cursor: &mut Cursor<Vec<u8>>, motion: &Motion) -> Result<(), Error> {
+fn write_motion<W: Write + Seek>(cursor: &mut W, motion: &Motion) -> Result<(), Error> {
     let anm_cnt = motion.animations.len();
     if anm_cnt > 3 {
         return Err(Error::new(
@@ -51,7 +51,8 @@ fn write_motion(cursor: &mut Cursor<Vec<u8>>, motion: &Motion) -> Result<(), Err
     //align
     const ALIGN: u64 = 4;
     const ALIGN_MASK: u64 = ALIGN - 1;
-    cursor.set_position((cursor.position() + ALIGN_MASK) & !ALIGN_MASK);
+    let pos = cursor.seek(SeekFrom::Current(0))?;
+    cursor.seek(SeekFrom::Start((pos + ALIGN_MASK) & !ALIGN_MASK))?;
 
     for script in motion.scripts.iter() {
         cursor.write_hash40::<LittleEndian>(*script)?;

src/disasm.rs

@@ -2,10 +2,9 @@ use crate::mlist::*;
 use byteorder::{LittleEndian, ReadBytesExt};
 use hash40::*;
 use indexmap::IndexMap;
-use std::io::{Cursor, Error, ErrorKind};
+use std::io::{Error, ErrorKind, Read, Seek, SeekFrom};
 
-pub fn disassemble(cursor: &mut Cursor<Vec<u8>>) -> Result<MList, Error> {
-    cursor.set_position(0);
+pub fn disassemble<R: Read + Seek>(cursor: &mut R) -> Result<MList, Error> {
     if MAGIC != cursor.read_hash40::<LittleEndian>()? {
         return Err(Error::new(
             ErrorKind::InvalidData,
@@ -28,7 +27,7 @@ pub fn disassemble(cursor: &mut Cursor<Vec<u8>>) -> Result<MList, Error> {
     })
 }
 
-fn read_motion(cursor: &mut Cursor<Vec<u8>>) -> Result<Motion, Error> {
+fn read_motion<R: Read + Seek>(cursor: &mut R) -> Result<Motion, Error> {
     let game_script = cursor.read_hash40::<LittleEndian>()?;
     let flags = cursor.read_u16::<LittleEndian>()?.into();
     let blend_frames = cursor.read_u8()?;
@@ -56,7 +55,8 @@ fn read_motion(cursor: &mut Cursor<Vec<u8>>) -> Result<Motion, Error> {
     //align by 4
     const ALIGN: u64 = 4;
     const ALIGN_MASK: u64 = ALIGN - 1;
-    cursor.set_position((cursor.position() + ALIGN_MASK) & !ALIGN_MASK);
+    let pos = cursor.seek(SeekFrom::Current(0))?;
+    cursor.seek(SeekFrom::Start((pos + ALIGN_MASK) & !ALIGN_MASK))?;
 
     let scripts = (0..size / 8)
         .map(|_| cursor.read_hash40::<LittleEndian>())

src/lib.rs

@@ -8,13 +8,28 @@ use std::fs::{read, File};
 use std::io::{prelude::*, Cursor, Error};
 use std::path::Path;
 
-pub use hash40;
 pub use diff;
+pub use hash40;
+
+/// Attempts to read a [MList] from the given reader (requires [Seek]).
+/// The reader should be positioned at the start of the filetype.
+/// Returns a [MList] if successful, otherwise an [Error].
+pub fn read_stream<R: Read + Seek>(reader: &mut R) -> Result<MList, Error> {
+    disasm::disassemble(reader)
+}
+
+/// Attempts to write a [MList] into the given writer (requires [Seek]).
+/// Returns nothing if successful, otherwise an [Error].
+pub fn write_stream<W: Write + Seek>(writer: &mut W, mlist: &MList) -> Result<(), Error> {
+    asm::assemble(writer, mlist)
+}
 
+/// Attempts to read a [MList] from a file path
 pub fn open<P: AsRef<Path>>(file: P) -> Result<MList, Error> {
     disasm::disassemble(&mut Cursor::new(read(file)?))
 }
 
+/// Attempts to write a [MList] to a file path
 pub fn save<P: AsRef<Path>>(path: P, mlist: &MList) -> Result<(), Error> {
     let mut file = File::create(path)?;
     let mut cursor = Cursor::new(Vec::<u8>::new());