Transforms for jsonb to PL/Perl

Add a new contrib module jsonb_plperl that provides a transform between
jsonb and PL/Perl.  jsonb values are converted to appropriate Perl types
such as arrays and hashes, and vice versa.

Author: Anthony Bykov <a.bykov@postgrespro.ru>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Reviewed-by: Aleksander Alekseev <a.alekseev@postgrespro.ru>
Reviewed-by: Nikita Glukhov <n.gluhov@postgrespro.ru>

1 files changed, 262 insertions, 0 deletions

diff --git a/contrib/jsonb_plperl/jsonb_plperl.c b/contrib/jsonb_plperl/jsonb_plperl.c
new file mode 100644
index 0000000000..918debdddb
--- /dev/null
+++ b/contrib/jsonb_plperl/jsonb_plperl.c
@@ -0,0 +1,262 @@
+#include "postgres.h"
+
+#undef _
+
+#include "fmgr.h"
+#include "plperl.h"
+#include "plperl_helpers.h"
+
+#include "utils/jsonb.h"
+#include "utils/fmgrprotos.h"
+
+PG_MODULE_MAGIC;
+
+static SV  *Jsonb_to_SV(JsonbContainer *jsonb);
+static JsonbValue *SV_to_JsonbValue(SV *obj, JsonbParseState **ps, bool is_elem);
+
+
+static SV *
+JsonbValue_to_SV(JsonbValue *jbv)
+{
+	dTHX;
+
+	switch (jbv->type)
+	{
+		case jbvBinary:
+			return newRV(Jsonb_to_SV(jbv->val.binary.data));
+
+		case jbvNumeric:
+			{
+				char	   *str = DatumGetCString(DirectFunctionCall1(numeric_out,
+																	  NumericGetDatum(jbv->val.numeric)));
+				SV		   *result = newSVnv(SvNV(cstr2sv(str)));
+				pfree(str);
+				return result;
+			}
+
+		case jbvString:
+			{
+				char	   *str = pnstrdup(jbv->val.string.val,
+										   jbv->val.string.len);
+				SV		   *result = cstr2sv(str);
+				pfree(str);
+				return result;
+			}
+
+		case jbvBool:
+			return newSVnv(SvNV(jbv->val.boolean ? &PL_sv_yes : &PL_sv_no));
+
+		case jbvNull:
+			return newSV(0);
+
+		default:
+			elog(ERROR, "unexpected jsonb value type: %d", jbv->type);
+			return NULL;
+	}
+}
+
+static SV  *
+Jsonb_to_SV(JsonbContainer *jsonb)
+{
+	dTHX;
+	JsonbValue	v;
+	JsonbIterator *it;
+	JsonbIteratorToken r;
+
+	it = JsonbIteratorInit(jsonb);
+	r = JsonbIteratorNext(&it, &v, true);
+
+	switch (r)
+	{
+		case WJB_BEGIN_ARRAY:
+			if (v.val.array.rawScalar)
+			{
+				JsonbValue	tmp;
+
+				if ((r = JsonbIteratorNext(&it, &v, true)) != WJB_ELEM ||
+					(r = JsonbIteratorNext(&it, &tmp, true)) != WJB_END_ARRAY ||
+					(r = JsonbIteratorNext(&it, &tmp, true)) != WJB_DONE)
+					elog(ERROR, "unexpected jsonb token: %d", r);
+
+				return newRV(JsonbValue_to_SV(&v));
+			}
+			else
+			{
+				AV		   *av = newAV();
+
+				while ((r = JsonbIteratorNext(&it, &v, true)) != WJB_DONE)
+				{
+					if (r == WJB_ELEM)
+						av_push(av, JsonbValue_to_SV(&v));
+				}
+
+				return (SV *) av;
+			}
+
+		case WJB_BEGIN_OBJECT:
+			{
+				HV		   *hv = newHV();
+
+				while ((r = JsonbIteratorNext(&it, &v, true)) != WJB_DONE)
+				{
+					if (r == WJB_KEY)
+					{
+						/* json key in v, json value in val */
+						JsonbValue	val;
+
+						if (JsonbIteratorNext(&it, &val, true) == WJB_VALUE)
+						{
+							SV		   *value = JsonbValue_to_SV(&val);
+
+							(void) hv_store(hv,
+											v.val.string.val, v.val.string.len,
+											value, 0);
+						}
+					}
+				}
+
+				return (SV *) hv;
+			}
+
+		default:
+			elog(ERROR, "unexpected jsonb token: %d", r);
+			return NULL;
+	}
+}
+
+static JsonbValue *
+AV_to_JsonbValue(AV *in, JsonbParseState **jsonb_state)
+{
+	dTHX;
+	SSize_t		pcount = av_len(in) + 1;
+	SSize_t		i;
+
+	pushJsonbValue(jsonb_state, WJB_BEGIN_ARRAY, NULL);
+
+	for (i = 0; i < pcount; i++)
+	{
+		SV		  **value = av_fetch(in, i, FALSE);
+
+		if (value)
+			(void) SV_to_JsonbValue(*value, jsonb_state, true);
+	}
+
+	return pushJsonbValue(jsonb_state, WJB_END_ARRAY, NULL);
+}
+
+static JsonbValue *
+HV_to_JsonbValue(HV *obj, JsonbParseState **jsonb_state)
+{
+	dTHX;
+	JsonbValue	key;
+	SV		   *val;
+
+	key.type = jbvString;
+
+	pushJsonbValue(jsonb_state, WJB_BEGIN_OBJECT, NULL);
+
+	(void) hv_iterinit(obj);
+
+	while ((val = hv_iternextsv(obj, &key.val.string.val, &key.val.string.len)))
+	{
+		key.val.string.val = pnstrdup(key.val.string.val, key.val.string.len);
+		pushJsonbValue(jsonb_state, WJB_KEY, &key);
+		(void) SV_to_JsonbValue(val, jsonb_state, false);
+	}
+
+	return pushJsonbValue(jsonb_state, WJB_END_OBJECT, NULL);
+}
+
+static JsonbValue *
+SV_to_JsonbValue(SV *in, JsonbParseState **jsonb_state, bool is_elem)
+{
+	dTHX;
+	JsonbValue	out;			/* result */
+
+	/* Dereference references recursively. */
+	while (SvROK(in))
+		in = SvRV(in);
+
+	switch (SvTYPE(in))
+	{
+		case SVt_PVAV:
+			return AV_to_JsonbValue((AV *) in, jsonb_state);
+
+		case SVt_PVHV:
+			return HV_to_JsonbValue((HV *) in, jsonb_state);
+
+		case SVt_NV:
+		case SVt_IV:
+			{
+				char	   *str = sv2cstr(in);
+
+				/*
+				 * Use case-insensitive comparison because infinity
+				 * representation varies across Perl versions.
+				 */
+				if (pg_strcasecmp(str, "inf") == 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 (errmsg("cannot convert infinite value to jsonb"))));
+
+				out.type = jbvNumeric;
+				out.val.numeric = DatumGetNumeric(DirectFunctionCall3(numeric_in,
+																	  CStringGetDatum(str), 0, -1));
+			}
+			break;
+
+		case SVt_NULL:
+			out.type = jbvNull;
+			break;
+
+		case SVt_PV:			/* string */
+			out.type = jbvString;
+			out.val.string.val = sv2cstr(in);
+			out.val.string.len = strlen(out.val.string.val);
+			break;
+
+		default:
+
+			/*
+			 * XXX It might be nice if we could include the Perl type in the
+			 * error message.
+			 */
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 (errmsg("cannot transform this Perl type to jsonb"))));
+			return NULL;
+	}
+
+	/* Push result into 'jsonb_state' unless it is a raw scalar. */
+	return *jsonb_state
+		? pushJsonbValue(jsonb_state, is_elem ? WJB_ELEM : WJB_VALUE, &out)
+		: memcpy(palloc(sizeof(JsonbValue)), &out, sizeof(JsonbValue));
+}
+
+
+PG_FUNCTION_INFO_V1(jsonb_to_plperl);
+
+Datum
+jsonb_to_plperl(PG_FUNCTION_ARGS)
+{
+	dTHX;
+	Jsonb	   *in = PG_GETARG_JSONB_P(0);
+	SV		   *sv = Jsonb_to_SV(&in->root);
+
+	return PointerGetDatum(newRV(sv));
+}
+
+
+PG_FUNCTION_INFO_V1(plperl_to_jsonb);
+
+Datum
+plperl_to_jsonb(PG_FUNCTION_ARGS)
+{
+	dTHX;
+	JsonbParseState *jsonb_state = NULL;
+	SV		   *in = (SV *) PG_GETARG_POINTER(0);
+	JsonbValue *out = SV_to_JsonbValue(in, &jsonb_state, true);
+	Jsonb	   *result = JsonbValueToJsonb(out);
+
+	PG_RETURN_JSONB_P(result);
+}