pushActiveVisitor static method
Sets visitor as the active visitor and returns the previously-active
one.
Hot-path companion to withActiveVisitor for callers that already own a
try/finally — most importantly InterpretedFunction.call, which runs
on every interpreted function call. Pairing pushActiveVisitor with
popActiveVisitor gives identical save/set/restore semantics (nesting
included) without allocating the T Function() closure that
withActiveVisitor requires per invocation.
Implementation
static InterpreterVisitor? pushActiveVisitor(InterpreterVisitor visitor) {
final previous = _activeVisitor;
_activeVisitor = visitor;
return previous;
}