Function deserialize_code

crates/compiler-core/src/marshal.rs:193–276

Deserialize a code object (CPython field order).

(
    rdr: &mut R,
    bag: Bag,
)

/// Deserialize a code object (CPython field order).
pub fn deserialize_code<R: Read, Bag: ConstantBag>(
    rdr: &mut R,
    bag: Bag,
) -> Result<CodeObject<Bag::Constant>> {
    // 1–5: scalar fields
    let arg_count = rdr.read_u32()?;
    let posonlyarg_count = rdr.read_u32()?;
    let kwonlyarg_count = rdr.read_u32()?;
    let max_stackdepth = rdr.read_u32()?;
    let flags = CodeFlags::from_bits_truncate(rdr.read_u32()?);

    // 6: co_code
    let code_bytes = read_marshal_bytes(rdr)?;

    // 7: co_consts
    let constants = read_marshal_const_tuple(rdr, bag)?;

    // 8: co_names
    let names = read_marshal_name_tuple(rdr, &bag)?;

    // 9: co_localsplusnames
    let localsplusnames = read_marshal_str_vec(rdr)?;

    // 10: co_localspluskinds
    let localspluskinds = read_marshal_bytes(rdr)?;

    // 11–13: filename, name, qualname
    let source_path = bag.make_name(&read_marshal_str(rdr)?);
    let obj_name = bag.make_name(&read_marshal_str(rdr)?);
    let qualname = bag.make_name(&read_marshal_str(rdr)?);

    // 14: co_firstlineno
    let first_line_raw = rdr.read_u32()? as i32;
    let first_line_number = if first_line_raw > 0 {
        OneIndexed::new(first_line_raw as usize)
    } else {
        None
    };

    // 15–16: linetable, exceptiontable
    let linetable = read_marshal_bytes(rdr)?.to_vec().into_boxed_slice();
    let exceptiontable = read_marshal_bytes(rdr)?.to_vec().into_boxed_slice();

    // Split localsplusnames/kinds → varnames/cellvars/freevars
    let lp = split_localplus(
        &localsplusnames
            .iter()
            .map(|s| s.as_str())
            .collect::<Vec<&str>>(),
        &localspluskinds,
        arg_count,
        kwonlyarg_count,
        flags,
    )?;

    // Bytecode already uses flat localsplus indices (no translation needed)
    let instructions = CodeUnits::try_from(code_bytes.as_slice())?;
    let locations = linetable_to_locations(&linetable, first_line_raw, instructions.len());