Add parsing of common SQL/JSON clauses

Author: Nikita Glukhov

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"
 
 
@@ -814,3 +815,39 @@ makeVacuumRelation(RangeVar *relation, Oid oid, List *va_cols)
 	v->va_cols = va_cols;
 	return v;
 }
+
+/*
+ * makeJsonValueExpr -
+ *	  creates a JsonValueExpr node
+ */
+JsonValueExpr *
+makeJsonValueExpr(Expr *expr, JsonFormat format)
+{
+	JsonValueExpr *jve = makeNode(JsonValueExpr);
+
+	jve->expr = expr;
+	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;
+}

src/backend/parser/gram.y

@@ -220,6 +220,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	JoinType			jtype;
 	DropBehavior		dbehavior;
 	OnCommitAction		oncommit;
+	JsonFormat			jsformat;
 	List				*list;
 	Node				*node;
 	Value				*value;
@@ -599,6 +600,15 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <list>		hash_partbound
 %type <defelt>		hash_partbound_elem
 
+%type <node>		json_value_expr
+					json_output_clause_opt
+
+%type <ival>		json_encoding
+					json_encoding_clause_opt
+
+%type <jsformat>	json_format_clause_opt
+					json_representation
+
 /*
  * Non-keyword token types.  These are hard-wired into the "flex" lexer.
  * They must be listed first so that their numeric codes do not depend on
@@ -650,7 +660,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	EXTENSION EXTERNAL EXTRACT
 
 	FALSE_P FAMILY FETCH FILTER FIRST_P FLOAT_P FOLLOWING FOR
-	FORCE FOREIGN FORWARD FREEZE FROM FULL FUNCTION FUNCTIONS
+	FORCE FOREIGN FORMAT FORWARD FREEZE FROM FULL FUNCTION FUNCTIONS
 
 	GENERATED GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING GROUPS
 
@@ -661,7 +671,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	INNER_P INOUT INPUT_P INSENSITIVE INSERT INSTEAD INT_P INTEGER
 	INTERSECT INTERVAL INTO INVOKER IS ISNULL ISOLATION
 
-	JOIN
+	JOIN JSON
 
 	KEY
 
@@ -729,9 +739,9 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
  */
 %token		NOT_LA NULLS_LA WITH_LA
 
-
 /* Precedence: lowest to highest */
 %nonassoc	SET				/* see relation_expr_opt_alias */
+%right		FORMAT
 %left		UNION EXCEPT
 %left		INTERSECT
 %left		OR
@@ -14635,6 +14645,58 @@ opt_asymmetric: ASYMMETRIC
 			| /*EMPTY*/
 		;
 
+/* SQL/JSON support */
+
+json_value_expr:
+			a_expr json_format_clause_opt
+			{
+				$$ = (Node *) makeJsonValueExpr((Expr *) $1, $2);
+			}
+		;
+
+json_format_clause_opt:
+			FORMAT json_representation
+				{
+					$$ = $2;
+					$$.location = @1;
+				}
+			| /* EMPTY */
+				{
+					$$.type = JS_FORMAT_DEFAULT;
+					$$.encoding = JS_ENC_DEFAULT;
+					$$.location = -1;
+				}
+		;
+
+json_representation:
+			JSON json_encoding_clause_opt
+				{
+					$$.type = JS_FORMAT_JSON;
+					$$.encoding = $2;
+					$$.location = @1;
+				}
+		/*	| implementation_defined_JSON_representation_option (BSON, AVRO etc) */
+		;
+
+json_encoding_clause_opt:
+			ENCODING json_encoding					{ $$ = $2; }
+			| /* EMPTY */							{ $$ = JS_ENC_DEFAULT; }
+		;
+
+json_encoding:
+			name									{ $$ = makeJsonEncoding($1); }
+		;
+
+json_output_clause_opt:
+			RETURNING Typename json_format_clause_opt
+				{
+					JsonOutput *n = makeNode(JsonOutput);
+					n->typeName = $2;
+					n->returning.format = $3;
+					$$ = (Node *) n;
+				}
+			| /* EMPTY */							{ $$ = NULL; }
+		;
 
 /*****************************************************************************
  *
@@ -15113,6 +15175,7 @@ unreserved_keyword:
 			| FIRST_P
 			| FOLLOWING
 			| FORCE
+			| FORMAT
 			| FORWARD
 			| FUNCTION
 			| FUNCTIONS
@@ -15144,6 +15207,7 @@ unreserved_keyword:
 			| INSTEAD
 			| INVOKER
 			| ISOLATION
+			| JSON
 			| KEY
 			| LABEL
 			| LANGUAGE

src/include/nodes/makefuncs.h

@@ -105,4 +105,7 @@ extern GroupingSet *makeGroupingSet(GroupingSetKind kind, List *content, int loc
 
 extern VacuumRelation *makeVacuumRelation(RangeVar *relation, Oid oid, List *va_cols);
 
+extern JsonValueExpr *makeJsonValueExpr(Expr *expr, JsonFormat format);
+extern JsonEncoding makeJsonEncoding(char *name);
+
 #endif							/* MAKEFUNC_H */

src/include/nodes/nodes.h

@@ -481,6 +481,8 @@ typedef enum NodeTag
 	T_PartitionRangeDatum,
 	T_PartitionCmd,
 	T_VacuumRelation,
+	T_JsonValueExpr,
+	T_JsonOutput,
 
 	/*
 	 * TAGS FOR REPLICATION GRAMMAR PARSE NODES (replnodes.h)

src/include/nodes/parsenodes.h

@@ -1486,6 +1486,31 @@ typedef struct TriggerTransition
 	bool		isTable;
 } TriggerTransition;
 
+/* Nodes for SQL/JSON support */
+
+/*
+ * JsonOutput -
+ *		representation of JSON output clause (RETURNING type [FORMAT format])
+ */
+typedef struct JsonOutput
+{
+	NodeTag		type;
+	TypeName   *typeName;		/* RETURNING type name, if specified */
+	JsonReturning returning;	/* RETURNING FORMAT clause and type Oids */
+} JsonOutput;
+
+/*
+ * JsonValueExpr -
+ *		representation of JSON value expression (expr [FORMAT json_format])
+ */
+typedef struct JsonValueExpr
+{
+	NodeTag		type;
+	Expr	   *expr;			/* raw expression */
+	JsonFormat  format;			/* FORMAT clause, if specified */
+} JsonValueExpr;
+
+
 /*****************************************************************************
  *		Raw Grammar Output Statements
  *****************************************************************************/

src/include/nodes/primnodes.h

@@ -1189,6 +1189,51 @@ typedef struct XmlExpr
 	int			location;		/* token location, or -1 if unknown */
 } XmlExpr;
 
+/*
+ * JsonEncoding -
+ *		representation of JSON ENCODING clause
+ */
+typedef enum JsonEncoding
+{
+	JS_ENC_DEFAULT,				/* unspecified */
+	JS_ENC_UTF8,
+	JS_ENC_UTF16,
+	JS_ENC_UTF32,
+} JsonEncoding;
+
+/*
+ * JsonFormatType -
+ *		enumeration of JSON formats used in JSON FORMAT clause
+ */
+typedef enum JsonFormatType
+{
+	JS_FORMAT_DEFAULT,			/* unspecified */
+	JS_FORMAT_JSON,				/* FORMAT JSON [ENCODING ...] */
+	JS_FORMAT_JSONB				/* implicit internal format for RETURNING jsonb */
+} JsonFormatType;
+
+/*
+ * JsonFormat -
+ *		representation of JSON FORMAT clause
+ */
+typedef struct JsonFormat
+{
+	JsonFormatType	type;		/* format type */
+	JsonEncoding	encoding;	/* JSON encoding */
+	int				location;	/* token location, or -1 if unknown */
+} JsonFormat;
+
+/*
+ * JsonReturning -
+ *		transformed representation of JSON RETURNING clause
+ */
+typedef struct JsonReturning
+{
+	JsonFormat	format;			/* output JSON format */
+	Oid			typid;			/* target type Oid */
+	int32		typmod;			/* target type modifier */
+} JsonReturning;
+
 /* ----------------
  * NullTest
  *

src/include/parser/kwlist.h

@@ -169,6 +169,7 @@ PG_KEYWORD("following", FOLLOWING, UNRESERVED_KEYWORD)
 PG_KEYWORD("for", FOR, RESERVED_KEYWORD)
 PG_KEYWORD("force", FORCE, UNRESERVED_KEYWORD)
 PG_KEYWORD("foreign", FOREIGN, RESERVED_KEYWORD)
+PG_KEYWORD("format", FORMAT, UNRESERVED_KEYWORD)
 PG_KEYWORD("forward", FORWARD, UNRESERVED_KEYWORD)
 PG_KEYWORD("freeze", FREEZE, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("from", FROM, RESERVED_KEYWORD)
@@ -221,6 +222,7 @@ PG_KEYWORD("is", IS, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("isnull", ISNULL, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("isolation", ISOLATION, UNRESERVED_KEYWORD)
 PG_KEYWORD("join", JOIN, TYPE_FUNC_NAME_KEYWORD)
+PG_KEYWORD("json", JSON, UNRESERVED_KEYWORD)
 PG_KEYWORD("key", KEY, UNRESERVED_KEYWORD)
 PG_KEYWORD("label", LABEL, UNRESERVED_KEYWORD)
 PG_KEYWORD("language", LANGUAGE, UNRESERVED_KEYWORD)