Create contrib/bool_plperl to provide a bool transform for PL/Perl[U].

plperl's default handling of bool arguments or results is not terribly
satisfactory, since Perl doesn't consider the string 'f' to be false.
Ideally we'd just fix that, but the backwards-compatibility hazard
would be substantial.  Instead, build a TRANSFORM module that can
be optionally applied to provide saner semantics.

Perhaps usefully, this is also about the minimum possible skeletal
example of a plperl transform module; so it might be a better starting
point for user-written transform modules than hstore_plperl or
jsonb_plperl.

Ivan Panchenko

Discussion: https://postgr.es/m/1583013317.881182688@f390.i.mail.ru

1 files changed, 66 insertions, 0 deletions

diff --git a/contrib/bool_plperl/sql/bool_plperl.sql b/contrib/bool_plperl/sql/bool_plperl.sql
new file mode 100644
index 00000000000..dd99f545ea9
--- /dev/null
+++ b/contrib/bool_plperl/sql/bool_plperl.sql
@@ -0,0 +1,66 @@
+CREATE EXTENSION bool_plperl CASCADE;
+
+--- test transforming from perl
+
+CREATE FUNCTION perl2int(int) RETURNS bool
+LANGUAGE plperl
+TRANSFORM FOR TYPE bool
+AS $$
+return shift;
+$$;
+
+CREATE FUNCTION perl2text(text) RETURNS bool
+LANGUAGE plperl
+TRANSFORM FOR TYPE bool
+AS $$
+return shift;
+$$;
+
+CREATE FUNCTION perl2undef() RETURNS bool
+LANGUAGE plperl
+TRANSFORM FOR TYPE bool
+AS $$
+return undef;
+$$;
+
+SELECT perl2int(1);
+SELECT perl2int(0);
+SELECT perl2text('foo');
+SELECT perl2text('');
+SELECT perl2undef() IS NULL AS p;
+
+--- test transforming to perl
+
+CREATE FUNCTION bool2perl(bool, bool, bool) RETURNS void
+LANGUAGE plperl
+TRANSFORM FOR TYPE bool
+AS $$
+my ($x, $y, $z) = @_;
+
+die("NULL mistransformed") if (defined($z));
+die("TRUE mistransformed to UNDEF") if (!defined($x));
+die("FALSE mistransformed to UNDEF") if (!defined($y));
+die("TRUE mistransformed") if (!$x);
+die("FALSE mistransformed") if ($y);
+$$;
+
+SELECT bool2perl (true, false, NULL);
+
+--- test selecting bool through SPI
+
+CREATE FUNCTION spi_test()  RETURNS void
+LANGUAGE plperl
+TRANSFORM FOR TYPE bool
+AS $$
+my $rv = spi_exec_query('SELECT true t, false f, NULL n')->{rows}->[0];
+
+die("TRUE mistransformed to UNDEF in SPI") if (!defined ($rv->{t}));
+die("FALSE mistransformed to UNDEF in SPI") if (!defined ($rv->{f}));
+die("NULL mistransformed in SPI") if (defined ($rv->{n}));
+die("TRUE mistransformed in SPI") if (!$rv->{t});
+die("FALSE mistransformed in SPI") if ($rv->{f});
+$$;
+
+SELECT spi_test();
+
+DROP EXTENSION plperl CASCADE;