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use v6;
use Test;
plan 29;
# L<S04/The do-once loop/"can't" put "statement modifier">
# Note in accordance with STD, conditionals are OK, loops are not.
eval_dies_ok 'my $i = 1; do { $i++ } while $i < 5;',
"'do' can't take the 'while' modifier";
eval_dies_ok 'my $i = 1; do { $i++ } until $i > 4;',
"'do' can't take the 'until' modifier";
eval_dies_ok 'my $i; do { $i++ } for 1..3;',
"'do' can't take the 'for' modifier";
eval_dies_ok 'my $i; do { $i++ } given $i;',
"'do' can't take the 'given' modifier";
eval_lives_ok 'my $i; do { $i++ } unless $i;',
"'do' can take the 'unless' modifier";
eval_lives_ok 'my $i = 1; do { $i++ } if $i;',
"'do' can take the 'if' modifier";
# L<S04/The do-once loop/statement "prefixing with" do>
{
my $x;
my ($a, $b, $c) = 'a' .. 'c';
$x = do if $a { $b } else { $c };
is $x, 'b', "prefixing 'if' statement with 'do' (then)";
$x = do if !$a { $b } else { $c };
is $x, 'c', "prefixing 'if' statement with 'do' (else)";
}
=begin comment
If the final statement is a conditional which does not execute
any branch, the return value is undefined in item context and ()
in list context.
=end comment
{
my $x = do if 0 { 1 } elsif 0 { 2 };
ok !$x.defined, 'when if does not execute any branch, return undefined';
$x = (42, do if 0 { 1 } elsif 0 { 2 }, 42);
#?rakudo todo 'Rakudo still uses Nil here'
is $x[1], (), 'when if does not execute any branch, returns ()';
}
{
my $ret = do given 3 {
when 3 { 1 }
};
is($ret, 1, 'do STMT works');
}
{
my $ret = do { given 3 {
when 3 { 1 }
} };
is($ret, 1, 'do { STMT } works');
}
# L<S04/The do-once loop/"you may use" do "on an expression">
{
my $ret = do 42;
is($ret, 42, 'do EXPR should also work (single number)');
$ret = do 3 + 2;
is($ret, 5, 'do EXPR should also work (simple + expr)');
$ret = do do 5;
is($ret, 5, 'nested do (1)');
$ret = do {do 5};
is($ret, 5, 'nested do (2)');
# precedence decisions do not cross a do boundary
$ret = 2 * do 2 + 5;
is($ret, 14, 'do affects precedence correctly');
}
# L<S04/The do-once loop/"can take" "loop control statements">
#?rakudo skip 'next without loop construct'
{
my $i;
my $ret = do {
$i++;
next;
$i--;
};
is $i, 1, "'next' works in 'do' block";
is $ret, (), "'next' in 'do' block drives return value";
}
#?rakudo 3 skip "Undeclared name A"
is EVAL('my $i; A: do { $i++; last A; $i-- }; $i'), 1,
"'last' works with label";
is EVAL('my $i; A: do { $i++; next A; $i-- }; $i'), 1,
"'next' works with label";
is EVAL('my $i; A: do { $i++; redo A until $i == 5; $i-- }; $i'), 4,
"'redo' works with label";
#?rakudo skip 'last without loop construct'
{
is EVAL('
my $i;
(
do {
$i++;
last;
$i--;
}),
$i;
'), ((),1), "'last' works in 'do' block and drives return value";
}
# IRC notes:
# <agentzh> audreyt: btw, can i use redo in the do-once loop?
# <audreyt> it can, and it will redo it
#?rakudo skip 'redo without loop construct'
{
is EVAL('
my $i;
do {
$i++;
redo if $i < 3;
$i--;
};
$i;
'), 2, "'redo' works in 'do' block";
}
# L<S04/The do-once loop/"bare block is not a do-once">
{
eval_dies_ok 'my $i; { $i++; next; $i--; }',
"bare block can't take 'next'";
eval_dies_ok 'my $i; { $i++; last; $i--; }',
"bare block can't take 'last'";
eval_dies_ok 'my $i; { $i++; redo; $i--; }',
"bare block can't take 'last'";
}
# L<S04/Statement parsing/"final closing curly on a line"
# reverts to semicolon>
{
my $a = do {
1 + 2;
} # no trailing `;'
is $a, 3, "final `}' on a line reverted to `;'";
}
lives_ok { my $a = do given 5 {} }, 'empty do block lives (RT 61034)';
# vim: ft=perl6
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