Right now PemReader uses interior mutability via RefCell, because peeking might involve filling an internal peek buffer (i.e. decoding the Base64 in a PEM document).
Rather than trying to hide the fact we're potentially modifying internal buffers (but not the cursor/position) when peeking, this changes the methods to explicitly accept &mut self, and with that change eliminates all usages of RefCell.
This change appears to have no practical drawbacks, since peeking always occurs during the decoding process where we need mutable access to the reader anyway.
Right now
PemReaderuses interior mutability viaRefCell, because peeking might involve filling an internal peek buffer (i.e. decoding the Base64 in a PEM document).Rather than trying to hide the fact we're potentially modifying internal buffers (but not the cursor/position) when peeking, this changes the methods to explicitly accept
&mut self, and with that change eliminates all usages ofRefCell.This change appears to have no practical drawbacks, since peeking always occurs during the decoding process where we need mutable access to the reader anyway.