Method repr

crates/vm/src/builtins/list.rs:590–631

(zelf: &Py<Self>, vm: &VirtualMachine)

impl Representable for PyList {
    #[inline]
    fn repr(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyRef<PyStr>> {
        if zelf.__len__() == 0 {
            return Ok(vm.ctx.intern_str("[]").to_owned());
        }

        if let Some(_guard) = ReprGuard::enter(vm, zelf.as_object()) {
            // Clone elements before calling repr to release the read lock.
            // Element repr may mutate the list (e.g., list.clear()), which
            // needs a write lock and would deadlock if read lock is held.
            let mut writer = Wtf8Buf::new();
            writer.push_char('[');

            let mut elements = zelf.borrow_vec().to_vec();
            let mut size = zelf.__len__();
            let mut first = true;
            let mut i = 0;
            while i < size {
                if elements.len() != size {
                    // `repr` mutated the list. refetch it.
                    elements = zelf.borrow_vec().to_vec();
                }

                let item = &elements[i];

                if first {
                    first = false;
                } else {
                    writer.push_str(", ");
                }

                writer.push_wtf8(item.repr(vm)?.as_wtf8());

                size = zelf.__len__(); // Refetch list size as `repr` may mutate the list.
                i += 1;
            }

            writer.push_char(']');
            Ok(vm.ctx.new_str(writer))
        } else {
            Ok(vm.ctx.intern_str("[...]").to_owned())
        }
    }

    fn repr_str(_zelf: &Py<Self>, _vm: &VirtualMachine) -> PyResult<String> {
        unreachable!("repr() is overridden directly")