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30 lines (26 loc) · 979 Bytes

use crate::{AsObject, PyObject, VirtualMachine};

pub struct ReprGuard<'vm> {

vm: &'vm VirtualMachine,

id: usize,

}

/// A guard to protect repr methods from recursion into itself,

impl<'vm> ReprGuard<'vm> {

/// Returns None if the guard against 'obj' is still held otherwise returns the guard. The guard

/// which is released if dropped.

pub fn enter(vm: &'vm VirtualMachine, obj: &PyObject) -> Option<Self> {

let mut guards = vm.repr_guards.borrow_mut();

// Should this be a flag on the obj itself? putting it in a global variable for now until it

// decided the form of PyObject. https://github.com/RustPython/RustPython/issues/371

let id = obj.get_id();

if guards.contains(&id) {

return None;

}

guards.insert(id);

Some(ReprGuard { vm, id })

}

impl<'vm> Drop for ReprGuard<'vm> {

fn drop(&mut self) {

self.vm.repr_guards.borrow_mut().remove(&self.id);

}

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