Add transforms feature

This provides a mechanism for specifying conversions between SQL data
types and procedural languages.  As examples, there are transforms
for hstore and ltree for PL/Perl and PL/Python.

reviews by Pavel Stěhule and Andres Freund

1 files changed, 32 insertions, 0 deletions

diff --git a/contrib/ltree_plpython/ltree_plpython.c b/contrib/ltree_plpython/ltree_plpython.c
new file mode 100644
index 00000000000..111e3e356e5
--- /dev/null
+++ b/contrib/ltree_plpython/ltree_plpython.c
@@ -0,0 +1,32 @@
+#include "postgres.h"
+#include "fmgr.h"
+#include "plpython.h"
+#include "ltree.h"
+
+PG_MODULE_MAGIC;
+
+
+PG_FUNCTION_INFO_V1(ltree_to_plpython);
+Datum ltree_to_plpython(PG_FUNCTION_ARGS);
+
+Datum
+ltree_to_plpython(PG_FUNCTION_ARGS)
+{
+	ltree	   *in = PG_GETARG_LTREE(0);
+	int			i;
+	PyObject   *list;
+	ltree_level *curlevel;
+
+	list = PyList_New(in->numlevel);
+
+	curlevel = LTREE_FIRST(in);
+	for (i = 0; i < in->numlevel; i++)
+	{
+		PyList_SetItem(list, i, PyString_FromStringAndSize(curlevel->name, curlevel->len));
+		curlevel = LEVEL_NEXT(curlevel);
+	}
+
+	PG_FREE_IF_COPY(in, 0);
+
+	return PointerGetDatum(list);
+}