Common SQL/JSON clauses

This introduces some of the building blocks used by the SQL/JSON
constructor and query functions. Specifically, it provides node
executor and grammar support for the FORMAT JSON [ENCODING foo]
clause, and values decorated with it, and for the RETURNING clause.

The following SQL/JSON patches will leverage these.

Nikita Glukhov (who probably deserves an award for perseverance).

Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu,
Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby.

Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru

1 files changed, 54 insertions, 0 deletions

diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index c85d8fe9751..867a927e7a0 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
+#include "utils/errcodes.h"
 #include "utils/lsyscache.h"
 
 
@@ -818,3 +819,56 @@ makeVacuumRelation(RangeVar *relation, Oid oid, List *va_cols)
 	v->va_cols = va_cols;
 	return v;
 }
+
+/*
+ * makeJsonFormat -
+ *	  creates a JsonFormat node
+ */
+JsonFormat *
+makeJsonFormat(JsonFormatType type, JsonEncoding encoding, int location)
+{
+	JsonFormat *jf = makeNode(JsonFormat);
+
+	jf->format_type = type;
+	jf->encoding = encoding;
+	jf->location = location;
+
+	return jf;
+}
+
+/*
+ * makeJsonValueExpr -
+ *	  creates a JsonValueExpr node
+ */
+JsonValueExpr *
+makeJsonValueExpr(Expr *expr, JsonFormat *format)
+{
+	JsonValueExpr *jve = makeNode(JsonValueExpr);
+
+	jve->raw_expr = expr;
+	jve->formatted_expr = NULL;
+	jve->format = format;
+
+	return jve;
+}
+
+/*
+ * makeJsonEncoding -
+ *	  converts JSON encoding name to enum JsonEncoding
+ */
+JsonEncoding
+makeJsonEncoding(char *name)
+{
+	if (!pg_strcasecmp(name, "utf8"))
+		return JS_ENC_UTF8;
+	if (!pg_strcasecmp(name, "utf16"))
+		return JS_ENC_UTF16;
+	if (!pg_strcasecmp(name, "utf32"))
+		return JS_ENC_UTF32;
+
+	ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			 errmsg("unrecognized JSON encoding: %s", name)));
+
+	return JS_ENC_DEFAULT;
+}