parser (roughly 80x faster).
The absolutely latest version of Bison (1.875c) is required for
reentrant GLR support, as well as a recent version of Flex (say,
2.5.31). Note that most Unix distributions ship with the
prehistoric Flex 2.5.4, which doesn't support reentrancy.
Nix. This is to prevent Berkeley DB from becoming wedged.
Unfortunately it is not possible to throw C++ exceptions from a
signal handler. In fact, you can't do much of anything except
change variables of type `volatile sig_atomic_t'. So we set an
interrupt flag in the signal handler and check it at various
strategic locations in the code (by calling checkInterrupt()).
Since this is unlikely to cover all cases (e.g., (semi-)infinite
loops), sometimes SIGTERM may now be required to kill Nix.
