msg-tool/src/utils/struct_pack.rs

//! Binary Struct Packing and Unpacking Utilities
use crate::types::Encoding;
use anyhow::Result;
use msg_tool_macro::struct_unpack_impl_for_num;
use std::io::{Read, Seek, Write};

/// Trait for unpacking a struct from a binary stream.
pub trait StructUnpack: Sized {
    /// Unpacks a struct from a binary stream.
    ///
    /// * `reader` - The reader to read the binary data from.
    /// * `big` - Whether the data is in big-endian format.
    /// * `encoding` - The encoding to use for string fields.
    fn unpack<R: Read + Seek>(reader: R, big: bool, encoding: Encoding) -> Result<Self>;
}

/// Trait for packing a struct into a binary stream.
pub trait StructPack: Sized {
    /// Packs a struct into a binary stream.
    ///
    /// * `writer` - The writer to write the binary data to.
    /// * `big` - Whether to use big-endian format.
    /// * `encoding` - The encoding to use for string fields.
    fn pack<W: Write>(&self, writer: &mut W, big: bool, encoding: Encoding) -> Result<()>;
}

impl<T: StructPack> StructPack for Vec<T> {
    fn pack<W: Write>(&self, writer: &mut W, big: bool, encoding: Encoding) -> Result<()> {
        for item in self {
            item.pack(writer, big, encoding)?;
        }
        Ok(())
    }
}

struct_unpack_impl_for_num!(u8);
struct_unpack_impl_for_num!(u16);
struct_unpack_impl_for_num!(u32);
struct_unpack_impl_for_num!(u64);
struct_unpack_impl_for_num!(u128);
struct_unpack_impl_for_num!(i8);
struct_unpack_impl_for_num!(i16);
struct_unpack_impl_for_num!(i32);
struct_unpack_impl_for_num!(i64);
struct_unpack_impl_for_num!(i128);
struct_unpack_impl_for_num!(f32);
struct_unpack_impl_for_num!(f64);

impl StructUnpack for bool {
    fn unpack<R: Read + Seek>(mut reader: R, _big: bool, _encoding: Encoding) -> Result<Self> {
        let mut buf = [0u8; 1];
        reader.read_exact(&mut buf)?;
        Ok(buf[0] != 0)
    }
}

impl StructPack for bool {
    fn pack<W: Write>(&self, writer: &mut W, _big: bool, _encoding: Encoding) -> Result<()> {
        writer.write_all(&[if *self { 1 } else { 0 }])?;
        Ok(())
    }
}

impl<T: StructPack> StructPack for Option<T> {
    fn pack<W: Write>(&self, writer: &mut W, big: bool, encoding: Encoding) -> Result<()> {
        if let Some(value) = self {
            value.pack(writer, big, encoding)?;
        }
        Ok(())
    }
}

impl<T: StructUnpack> StructUnpack for Option<T> {
    fn unpack<R: Read + Seek>(reader: R, big: bool, encoding: Encoding) -> Result<Self> {
        let value = T::unpack(reader, big, encoding)?;
        Ok(Some(value))
    }
}