Introduce convenience macros to hide JsonbContainer header accesses better.

This improves readability a bit and may make future improvements easier.

In passing, make sure that the JB_ROOT_IS_XXX macros deliver boolean (0/1)
results; the previous coding was a bug hazard, though no actual bugs are
known.

Nikita Glukhov, extended a bit by me

Discussion: https://postgr.es/m/9e21a39c-c1d7-b9b5-44a0-c5345a5029f6@postgrespro.ru

src/backend/utils/adt/jsonb_util.c

@@ -328,7 +328,7 @@ findJsonbValueFromContainer(JsonbContainer *container, uint32 flags,
 							JsonbValue *key)
 {
 	JEntry	   *children = container->children;
-	int			count = (container->header & JB_CMASK);
+	int			count = JsonContainerSize(container);
 	JsonbValue *result;
 
 	Assert((flags & ~(JB_FARRAY | JB_FOBJECT)) == 0);
@@ -339,7 +339,7 @@ findJsonbValueFromContainer(JsonbContainer *container, uint32 flags,
 
 	result = palloc(sizeof(JsonbValue));
 
-	if (flags & JB_FARRAY & container->header)
+	if ((flags & JB_FARRAY) && JsonContainerIsArray(container))
 	{
 		char	   *base_addr = (char *) (children + count);
 		uint32		offset = 0;
@@ -358,7 +358,7 @@ findJsonbValueFromContainer(JsonbContainer *container, uint32 flags,
 			JBE_ADVANCE_OFFSET(offset, children[i]);
 		}
 	}
-	else if (flags & JB_FOBJECT & container->header)
+	else if ((flags & JB_FOBJECT) && JsonContainerIsObject(container))
 	{
 		/* Since this is an object, account for *Pairs* of Jentrys */
 		char	   *base_addr = (char *) (children + count * 2);
@@ -422,10 +422,10 @@ getIthJsonbValueFromContainer(JsonbContainer *container, uint32 i)
 	char	   *base_addr;
 	uint32		nelements;
 
-	if ((container->header & JB_FARRAY) == 0)
+	if (!JsonContainerIsArray(container))
 		elog(ERROR, "not a jsonb array");
 
-	nelements = container->header & JB_CMASK;
+	nelements = JsonContainerSize(container);
 	base_addr = (char *) &container->children[nelements];
 
 	if (i >= nelements)
@@ -904,7 +904,7 @@ iteratorFromContainer(JsonbContainer *container, JsonbIterator *parent)
 	it = palloc(sizeof(JsonbIterator));
 	it->container = container;
 	it->parent = parent;
-	it->nElems = container->header & JB_CMASK;
+	it->nElems = JsonContainerSize(container);
 
 	/* Array starts just after header */
 	it->children = container->children;
@@ -914,7 +914,7 @@ iteratorFromContainer(JsonbContainer *container, JsonbIterator *parent)
 		case JB_FARRAY:
 			it->dataProper =
 				(char *) it->children + it->nElems * sizeof(JEntry);
-			it->isScalar = (container->header & JB_FSCALAR) != 0;
+			it->isScalar = JsonContainerIsScalar(container);
 			/* This is either a "raw scalar", or an array */
 			Assert(!it->isScalar || it->nElems == 1);
 

src/backend/utils/adt/jsonfuncs.c

@@ -1266,10 +1266,10 @@ get_jsonb_path_all(FunctionCallInfo fcinfo, bool as_text)
 				uint32		nelements;
 
 				/* Container must be array, but make sure */
-				if ((container->header & JB_FARRAY) == 0)
+				if (!JsonContainerIsArray(container))
 					elog(ERROR, "not a jsonb array");
 
-				nelements = container->header & JB_CMASK;
+				nelements = JsonContainerSize(container);
 
 				if (-lindex > nelements)
 					PG_RETURN_NULL();

src/include/utils/jsonb.h

@@ -205,6 +205,12 @@ typedef struct JsonbContainer
 #define JB_FOBJECT				0x20000000
 #define JB_FARRAY				0x40000000
 
+/* convenience macros for accessing a JsonbContainer struct */
+#define JsonContainerSize(jc)		((jc)->header & JB_CMASK)
+#define JsonContainerIsScalar(jc)	(((jc)->header & JB_FSCALAR) != 0)
+#define JsonContainerIsObject(jc)	(((jc)->header & JB_FOBJECT) != 0)
+#define JsonContainerIsArray(jc)	(((jc)->header & JB_FARRAY) != 0)
+
 /* The top-level on-disk format for a jsonb datum. */
 typedef struct
 {
@@ -213,10 +219,10 @@ typedef struct
 } Jsonb;
 
 /* convenience macros for accessing the root container in a Jsonb datum */
-#define JB_ROOT_COUNT(jbp_)		( *(uint32*) VARDATA(jbp_) & JB_CMASK)
-#define JB_ROOT_IS_SCALAR(jbp_) ( *(uint32*) VARDATA(jbp_) & JB_FSCALAR)
-#define JB_ROOT_IS_OBJECT(jbp_) ( *(uint32*) VARDATA(jbp_) & JB_FOBJECT)
-#define JB_ROOT_IS_ARRAY(jbp_)	( *(uint32*) VARDATA(jbp_) & JB_FARRAY)
+#define JB_ROOT_COUNT(jbp_)		(*(uint32 *) VARDATA(jbp_) & JB_CMASK)
+#define JB_ROOT_IS_SCALAR(jbp_) ((*(uint32 *) VARDATA(jbp_) & JB_FSCALAR) != 0)
+#define JB_ROOT_IS_OBJECT(jbp_) ((*(uint32 *) VARDATA(jbp_) & JB_FOBJECT) != 0)
+#define JB_ROOT_IS_ARRAY(jbp_)	((*(uint32 *) VARDATA(jbp_) & JB_FARRAY) != 0)
 
 
 enum jbvType