user_signal

catch_interrupt_exception(Call,Result) :-
    catch( call(Call),
    E,
    (E==user_interrupt_signal -> Result=interrupted ; throw(E))),
    (Result == interrupted -> true ; Result=ok).

foreign(user_signal_init, user_signal_init).

foreign(set_user_signal_mode, set_user_signal_mode(+integer,+integer)).

foreign(get_user_signal_mode, get_user_signal_mode([-integer])).

foreign(get_user_sig_reference, get_user_sig_reference([-integer])).

foreign_resource(user_signal, [set_user_signal_mode,get_user_signal_mode,user_signal_init,get_user_sig_reference]).

get_user_signal_ref(Ref) :-
    loadfr,
    get_user_sig_reference(Ref).

ignore_user_interrupt_det(Call) :-
    loadfr,
    get_user_signal_mode(Mode),
    call_cleanup( (set_user_signal_mode(0,0), call(Call), !), % 0=status_ignore; CTRL-C completely ignored
    set_user_signal_mode(0,Mode)).

init_user_signal(Res) :- catch((loadfr,(loaded(success) -> Res=ok ; Res=fail)), Exc, Res=Exc).

loadfr :-
    ( loaded(_) -> true
    ; safe_load_foreign_resource(user_signal,user_signal)
    -> user_signal_init,
    %write(user_signal_int),nl,
    assertz(loaded(success))
    ; format(user_output,"You can set the environment variable no_interrupts to true to avoid using the user_interrupt library~n",[]),
    assertz(loaded(failure))
).

protect_from_user_interrupt_det(Call) :-
    loadfr,
    get_user_signal_mode(Mode),
    call_cleanup( (set_user_signal_mode(0,1), call(Call), !), % look_for_queued=0, 1=status_protected; CTRL-C queued
    set_user_signal_mode(1,Mode)). % look_for_queued=1 -> raise exception if one is queued

user_interruptable_call_det(Call,Result) :-
    loadfr,
    get_user_signal_mode(Mode),
    call_cleanup( (set_user_signal_mode(1,2), % 2=status_default -> raise exceptions
    catch_interrupt_exception(Call,Result),!),
    set_user_signal_mode(1,Mode)). % look_for_queued=1 -> raise exception if one is queued