#!./perl

#
# test recursive functions.
#

BEGIN {
    require "./test.pl";
    plan(tests => 28);
}

sub gcd {
    return gcd(@_[0] - @_[1], @_[1]) if (@_[0] +> @_[1]);
    return gcd(@_[0], @_[1] - @_[0]) if (@_[0] +< @_[1]);
    @_[0];
}

sub factorial {
    @_[0] +< 2 ?? 1 !! @_[0] * factorial(@_[0] - 1);
}

sub fibonacci {
    @_[0] +< 2 ?? 1 !! fibonacci(@_[0] - 2) + fibonacci(@_[0] - 1);
}

# Highly recursive, highly aggressive.
# Kids, don't try this at home.
#
# For example ackermann(4,1) will take quite a long time.
# It will simply eat away your memory. Trust me.

sub ackermann {
    return @_[1] + 1               if (@_[0] == 0);
    return ackermann(@_[0] - 1, 1) if (@_[1] == 0);
    ackermann(@_[0] - 1, ackermann(@_[0], @_[1] - 1));
}

# Highly recursive, highly boring.

sub takeuchi {
    @_[1] +< @_[0] ??
	takeuchi(takeuchi(@_[0] - 1, @_[1], @_[2]),
		 takeuchi(@_[1] - 1, @_[2], @_[0]),
		 takeuchi(@_[2] - 1, @_[0], @_[1]))
	    !! @_[2];
}

is(gcd(1147, 1271), 31, "gcd(1147, 1271) == 31");

is(gcd(1908, 2016), 36, "gcd(1908, 2016) == 36");

is(factorial(10), 3628800, "factorial(10) == 3628800");

is(factorial(factorial(3)), 720, "factorial(factorial(3)) == 720");

is(fibonacci(10), 89, "fibonacci(10) == 89");

is(fibonacci(fibonacci(7)), 17711, "fibonacci(fibonacci(7)) == 17711");

my @ack = qw(1 2 3 4 2 3 4 5 3 5 7 9 5 13 29 61);

for my $x (0..3) { 
    for my $y (0..3) {
	my $a = ackermann($x, $y);
	is($a, shift(@ack), "ackermann($x, $y) == $a");
    }
}

my @($x, $y, $z) = @(18, 12, 6);

is(takeuchi($x, $y, $z), $z + 1, "takeuchi($x, $y, $z) == $z + 1");

do {
    sub get_first1 {
	get_list1(< @_)->[0];
    }

    sub get_list1 {
	return \@(curr_test) unless @_[0];
	my $u = get_first1(0);
	\@($u);
    }
    my $x = get_first1(1);
    ok($x, "premature FREETMPS (change 5699)");
};

do {
    sub get_first2 {
	return get_list2(< @_)->[0];
    }

    sub get_list2 {
	return \@(curr_test) unless @_[0];
	my $u = get_first2(0);
	return \@($u);
    }
    my $x = get_first2(1);
    ok($x, "premature FREETMPS (change 5699)");
};

do {
    local $^WARNING = 0; # We do not need recursion depth warning.

    sub sillysum {
	return @_[0] + (@_[0] +> 0 ?? sillysum(@_[0] - 1) !! 0);
    }

    is(sillysum(1000), 1000*1001/2, "recursive sum of 1..1000");
};

# check ok for recursion depth > 65536
do {
    my $r;
    try { 
	$r = runperl(
		     nolib => 1,
		     stderr => 1,
		     prog => q{our $d=0; our $e=1; sub c { ++$d; if ($d +> 66000) { $e=0 } else { c(); c() unless $d % 32768 } --$d } c(); exit $e});
    };
  SKIP: do {
      skip("Out of memory -- increase your data/heap?", 2)
	  if $r =~ m/Out of memory/i;
      is($r, '', "64K deep recursion - no output expected");

      if ($^OS_NAME eq 'MacOS') {
          ok(1, "$^OS_NAME: \$? is unreliable");
      } else {
          is($^CHILD_ERROR, 0, "64K deep recursion - no coredump expected");
      }

  };
};