Mahdi ramezaan zaadeandAlexander Medvednikov
8a9c408e0f
* cell: add RefCell runtime borrow-checked container (fixes #30306) * cell: panic on conflicting exclusive callback access --------- Co-authored-by: Alexander Medvednikov <alexander@medvednikov.com>
cell
RefCell[T] checks callback access at runtime for single-threaded code.
Use new_ref_cell(value) to create a cell, with(callback) to read its value,
and with_mut(callback) to replace it with the callback's return value.
Shared callbacks may nest. An exclusive callback excludes both shared and exclusive access.
The try_with and try_borrow methods return none on a conflicting exclusive borrow;
try_with_mut returns false on any conflict. The other methods panic on conflicts.
Borrow counts are released when a callback returns. try_borrow does not keep a borrow active.
Values follow ordinary V assignment semantics, including references contained in T;
the cell does not provide deep copies or track aliases retained outside callbacks.
Do not mutate such aliases during shared access. Cells do not synchronize access across threads.