use v6-alpha;

use Test;

plan 10;

# L<S04/Closure traits/KEEP "at every successful block exit">
# L<S04/Closure traits/UNDO "at every unsuccessful block exit">

{
    my $str;
    my sub is_pos ($n) {
        return (($n > 0) ?? 1 !! undef);
        KEEP { $str ~= "$n > 0 " }
        UNDO { $str ~= "$n <= 0 " }
    }

    ok is_pos(1), 'is_pos worked for 1';
    is $str, '1 > 0 ', 'KEEP ran as expected';

    ok !is_pos(0), 'is_pos worked for 0';
    is $str, '1 > 0 0 <= 0 ', 'UNDO worked as expected';

    ok !is_pos(-1), 'is_pos worked for 0';
    is $str, '1 > 0 0 <= 0 -1 <= 0 ', 'UNDO worked as expected';
}

# L<S04/Closure traits/KEEP UNDO are "variants of LEAVE"
#   "treated as part of the queue of LEAVE blocks">
{
    my $str;
    my sub is_pos($n) {
        return (($n > 0) ?? 1 !! undef);
        LEAVE { $str ~= ")" }
        KEEP { $str ~= "$n > 0" }
        UNDO { $str ~= "$n <= 0" }
        LEAVE { $str ~= "(" }
    }

    is_pos(1);
    is $str, '(1 > 0)', 'KEEP triggered as part of LEAVE blocks';

    is_pos(-5);
    is $str, '(1 > 0)(-5 <= 0)', 'UNDO triggered as part of LEAVE blocks';
}

# L<S04/Closure traits/"can occur multiple times">

# multiple KEEP/UNDO
{
    my $str;
    {
        KEEP { $str ~= 'K1 ' }
        KEEP { $str ~= 'K2 ' }
        UNDO { $str ~= 'U1 ' }
        UNDO { $str ~= 'U2 ' }
        1;
    }
    is $str, 'K2 K1 ', '2 KEEP blocks triggered';
}

{
    my $str;
    {
        KEEP { $str ~= 'K1 ' }
        KEEP { $str ~= 'K2 ' }
        UNDO { $str ~= 'U1 ' }
        UNDO { $str ~= 'U2 ' }
    }
    is $str, 'U2 U1 ', '2 UNDO blocks triggered';
}