Add SQL/JSON IS JSON parsing

Author: Nikita Glukhov

src/backend/nodes/makefuncs.c

@@ -883,3 +883,21 @@ makeJsonKeyValue(Node *key, Node *value)
 
 	return (Node *) n;
 }
+
+/*
+ * makeJsonIsPredicate -
+ *	  creates a JsonIsPredicate node
+ */
+Node *
+makeJsonIsPredicate(Node *expr, JsonFormat *format, JsonValueType value_type,
+					bool unique_keys)
+{
+	JsonIsPredicate *n = makeNode(JsonIsPredicate);
+
+	n->expr = expr;
+	n->format = format;
+	n->value_type = value_type;
+	n->unique_keys = unique_keys;
+
+	return (Node *) n;
+}

src/backend/parser/gram.y

@@ -622,6 +622,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 
 %type <ival>		json_encoding
 					json_encoding_clause_opt
+					json_predicate_type_constraint_opt
 
 %type <boolean>		json_key_uniqueness_constraint_opt
 					json_object_constructor_null_clause_opt
@@ -691,7 +692,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 
 	JOIN JSON JSON_ARRAY JSON_ARRAYAGG JSON_OBJECT JSON_OBJECTAGG
 
-	KEY KEYS
+	KEY KEYS KEEP
 
 	LABEL LANGUAGE LARGE_P LAST_P LATERAL_P
 	LEADING LEAKPROOF LEAST LEFT LEVEL LIKE LIMIT LISTEN LOAD LOCAL
@@ -719,9 +720,9 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	RESET RESTART RESTRICT RETURNING RETURNS REVOKE RIGHT ROLE ROLLBACK ROLLUP
 	ROUTINE ROUTINES ROW ROWS RULE
 
-	SAVEPOINT SCHEMA SCHEMAS SCROLL SEARCH SECOND_P SECURITY SELECT SEQUENCE SEQUENCES
-	SERIALIZABLE SERVER SESSION SESSION_USER SET SETS SETOF SHARE SHOW
-	SIMILAR SIMPLE SKIP SMALLINT SNAPSHOT SOME SQL_P STABLE STANDALONE_P
+	SAVEPOINT SCALAR SCHEMA SCHEMAS SCROLL SEARCH SECOND_P SECURITY SELECT
+	SEQUENCE SEQUENCES SERIALIZABLE SERVER SESSION SESSION_USER SET SETS SETOF
+	SHARE SHOW SIMILAR SIMPLE SKIP SMALLINT SNAPSHOT SOME SQL_P STABLE STANDALONE_P
 	START STATEMENT STATISTICS STDIN STDOUT STORAGE STORED STRICT_P STRIP_P
 	SUBSCRIPTION SUBSTRING SUPPORT SYMMETRIC SYSID SYSTEM_P
 
@@ -13375,6 +13376,48 @@ a_expr:		c_expr									{ $$ = $1; }
 				{
 					$$ = makeNotExpr((Node *) makeFuncCall(SystemFuncName("is_normalized"), list_make2($1, makeStringConst($4, @4)), @2), @2);
 				}
+			| a_expr
+				IS JSON
+					json_predicate_type_constraint_opt
+					json_key_uniqueness_constraint_opt		%prec IS
+				{
+					JsonFormat *format = makeJsonFormat(JS_FORMAT_DEFAULT, JS_ENC_DEFAULT, -1);
+					$$ = makeJsonIsPredicate($1, format, $4, $5);
+				}
+			/*
+			 * Required by standard, but it would conflict with expressions
+			 * like: 'str' || format(...)
+			| a_expr
+				FORMAT json_representation
+				IS JSON
+					json_predicate_type_constraint_opt
+					json_key_uniqueness_constraint_opt		%prec FORMAT
+				{
+					$3.location = @2;
+					$$ = makeJsonIsPredicate($1, $3, $6, $7);
+				}
+			*/
+			| a_expr
+				IS NOT JSON
+					json_predicate_type_constraint_opt
+					json_key_uniqueness_constraint_opt		%prec IS
+				{
+					JsonFormat *format = makeJsonFormat(JS_FORMAT_DEFAULT, JS_ENC_DEFAULT, -1);
+					$$ = makeNotExpr(makeJsonIsPredicate($1, format, $5, $6), @1);
+				}
+			/*
+			 * Required by standard, but it would conflict with expressions
+			 * like: 'str' || format(...)
+			| a_expr
+				FORMAT json_representation
+				IS NOT JSON
+					json_predicate_type_constraint_opt
+					json_key_uniqueness_constraint_opt		%prec FORMAT
+				{
+					$3.location = @2;
+					$$ = makeNotExpr(makeJsonIsPredicate($1, $3, $7, $8), @1);
+				}
+			*/
 			| DEFAULT
 				{
 					/*
@@ -13467,6 +13510,14 @@ b_expr:		c_expr
 				}
 		;
 
+json_predicate_type_constraint_opt:
+			VALUE_P									{ $$ = JS_TYPE_ANY; }
+			| ARRAY									{ $$ = JS_TYPE_ARRAY; }
+			| OBJECT_P								{ $$ = JS_TYPE_OBJECT; }
+			| SCALAR								{ $$ = JS_TYPE_SCALAR; }
+			| /* EMPTY */							{ $$ = JS_TYPE_ANY; }
+		;
+
 json_key_uniqueness_constraint_opt:
 			WITH_LA_UNIQUE UNIQUE opt_keys			{ $$ = true; }
 			| WITHOUT UNIQUE opt_keys				{ $$ = false; }
@@ -15540,6 +15591,7 @@ unreserved_keyword:
 			| ROWS
 			| RULE
 			| SAVEPOINT
+			| SCALAR
 			| SCHEMA
 			| SCHEMAS
 			| SCROLL

src/include/nodes/makefuncs.h

@@ -109,6 +109,8 @@ extern JsonFormat *makeJsonFormat(JsonFormatType type, JsonEncoding encoding,
 								  int location);
 extern JsonValueExpr *makeJsonValueExpr(Expr *expr, JsonFormat *format);
 extern Node *makeJsonKeyValue(Node *key, Node *value);
+extern Node *makeJsonIsPredicate(Node *expr, JsonFormat *format,
+								 JsonValueType vtype, bool unique_keys);
 extern JsonEncoding makeJsonEncoding(char *name);
 
 #endif							/* MAKEFUNC_H */

src/include/nodes/nodes.h

@@ -491,6 +491,7 @@ typedef enum NodeTag
 	T_JsonAggConstructor,
 	T_JsonObjectAgg,
 	T_JsonArrayAgg,
+	T_JsonIsPredicate,
 	T_JsonKeyValue,
 	T_JsonOutput,
 

src/include/nodes/parsenodes.h

@@ -1499,6 +1499,32 @@ typedef struct JsonOutput
 	JsonReturning *returning;	/* RETURNING FORMAT clause and type Oids */
 } JsonOutput;
 
+/*
+ * JsonValueType -
+ *		representation of JSON item type in IS JSON predicate
+ */
+typedef enum JsonValueType
+{
+	JS_TYPE_ANY,				/* IS JSON [VALUE] */
+	JS_TYPE_OBJECT,				/* IS JSON OBJECT */
+	JS_TYPE_ARRAY,				/* IS JSON ARRAY*/
+	JS_TYPE_SCALAR				/* IS JSON SCALAR */
+} JsonValueType;
+
+/*
+ * JsonIsPredicate -
+ *		untransformed representation of IS JSON predicate
+ */
+typedef struct JsonIsPredicate
+{
+	NodeTag		type;
+	Node	   *expr;			/* untransformed expression */
+	JsonFormat *format;			/* FORMAT clause, if specified */
+	JsonValueType value_type;	/* JSON item type */
+	bool		unique_keys;	/* check key uniqueness? */
+	int			location;		/* token location, or -1 if unknown */
+} JsonIsPredicate;
+
 /*
  * JsonKeyValue -
  *		untransformed representation of JSON object key-value pair for

src/include/parser/kwlist.h

@@ -365,6 +365,7 @@ PG_KEYWORD("row", ROW, COL_NAME_KEYWORD)
 PG_KEYWORD("rows", ROWS, UNRESERVED_KEYWORD)
 PG_KEYWORD("rule", RULE, UNRESERVED_KEYWORD)
 PG_KEYWORD("savepoint", SAVEPOINT, UNRESERVED_KEYWORD)
+PG_KEYWORD("scalar", SCALAR, UNRESERVED_KEYWORD)
 PG_KEYWORD("schema", SCHEMA, UNRESERVED_KEYWORD)
 PG_KEYWORD("schemas", SCHEMAS, UNRESERVED_KEYWORD)
 PG_KEYWORD("scroll", SCROLL, UNRESERVED_KEYWORD)