//! Checkpoint and speculative allocation support.
/// A checkpoint for speculative allocation.
////// Allows saving the allocator state and rolling back.
pubstructMkCheckpoint{saved_head:usize,
}implMkCheckpoint{/// Create a new checkpoint.
pub(crate)fnnew(head:usize)->Self{Self{ saved_head: head }}/// Get the saved head position.
pubfnsaved_head(&self)->usize{self.saved_head
}}