More jsonb cleanup.

Fix JSONB_MAX_ELEMS and JSONB_MAX_PAIRS macros to use CB_MASK in the
calculation. JENTRY_POSMASK happens to have the same value at the moment,
but that's just coincidental.

Refactor jsonb iterator functions, for readability.

Get rid of the JENTRY_ISFIRST flag. Whenever we handle JEntrys, we have
access to the whole array and have enough context information to know
which entry is the first. This frees up one bit in the JEntry header for
future use. While we're at it, shuffle the JEntry bits so that boolean
true and false go together, for aesthetic reasons.

Bump catalog version as this changes the on-disk format slightly.

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201405091
+#define CATALOG_VERSION_NO	201405092
 
 #endif

src/include/utils/jsonb.h

@@ -130,17 +130,16 @@ typedef uint32 JEntry;
 
 #define JENTRY_POSMASK			0x0FFFFFFF
 #define JENTRY_TYPEMASK			0x70000000
-#define JENTRY_ISFIRST			0x80000000
 
 /* values stored in the type bits */
 #define JENTRY_ISSTRING			0x00000000
 #define JENTRY_ISNUMERIC		0x10000000
-#define JENTRY_ISCONTAINER		0x20000000		/* array or object */
-#define JENTRY_ISBOOL_FALSE		0x30000000
+#define JENTRY_ISBOOL_FALSE		0x20000000
+#define JENTRY_ISBOOL_TRUE		0x30000000
 #define JENTRY_ISNULL			0x40000000
-#define JENTRY_ISBOOL_TRUE		0x70000000
+#define JENTRY_ISCONTAINER		0x50000000		/* array or object */
 
-/* Note possible multiple evaluations, also access to prior array element */
+/* Note possible multiple evaluations */
 #define JBE_ISFIRST(je_)		(((je_) & JENTRY_ISFIRST) != 0)
 #define JBE_ISSTRING(je_)		(((je_) & JENTRY_TYPEMASK) == JENTRY_ISSTRING)
 #define JBE_ISNUMERIC(je_)		(((je_) & JENTRY_TYPEMASK) == JENTRY_ISNUMERIC)
@@ -150,12 +149,14 @@ typedef uint32 JEntry;
 #define JBE_ISBOOL_FALSE(je_)	(((je_) & JENTRY_TYPEMASK) == JENTRY_ISBOOL_FALSE)
 #define JBE_ISBOOL(je_)			(JBE_ISBOOL_TRUE(je_) || JBE_ISBOOL_FALSE(je_))
 
-/* Get offset for Jentry  */
+/*
+ * Macros for getting the offset and length of an element. Note multiple
+ * evaluations and access to prior array element.
+ */
 #define JBE_ENDPOS(je_)			((je_) & JENTRY_POSMASK)
-#define JBE_OFF(je_)			(JBE_ISFIRST(je_) ? 0 : JBE_ENDPOS((&(je_))[-1]))
-#define JBE_LEN(je_)			(JBE_ISFIRST(je_) ? \
-								 JBE_ENDPOS(je_) \
-								 : JBE_ENDPOS(je_) - JBE_ENDPOS((&(je_))[-1]))
+#define JBE_OFF(ja, i)			((i) == 0 ? 0 : JBE_ENDPOS((ja)[i - 1]))
+#define JBE_LEN(ja, i)			((i) == 0 ? JBE_ENDPOS((ja)[i]) \
+								 : JBE_ENDPOS((ja)[i]) - JBE_ENDPOS((ja)[i - 1]))
 
 /*
  * A jsonb array or object node, within a Jsonb Datum.
@@ -241,7 +242,7 @@ struct JsonbValue
 		{
 			int			len;
 			JsonbContainer *data;
-		}			binary;
+		}			binary;		/* Array or object, in on-disk format */
 	}			val;
 };
 
@@ -277,32 +278,29 @@ typedef struct JsonbParseState
  */
 typedef enum
 {
-	jbi_start = 0x0,
-	jbi_key,
-	jbi_value,
-	jbi_elem
+	JBI_ARRAY_START,
+	JBI_ARRAY_ELEM,
+	JBI_OBJECT_START,
+	JBI_OBJECT_KEY,
+	JBI_OBJECT_VALUE
 } JsonbIterState;
 
 typedef struct JsonbIterator
 {
-	/* Jsonb varlena buffer (may or may not be root) */
-	char	   *buffer;
-
-	/* Current value */
-	uint32		containerType;	/* Never of value JB_FSCALAR, since scalars
-								 * will appear in pseudo-arrays */
-	uint32		nElems;			/* Number of elements in metaArray (will be
+	/* Container being iterated */
+	JsonbContainer *container;
+	uint32		nElems;			/* Number of elements in children array (will be
 								 * nPairs for objects) */
 	bool		isScalar;		/* Pseudo-array scalar value? */
-	JEntry	   *meta;
+	JEntry	   *children;
 
 	/* Current item in buffer (up to nElems, but must * 2 for objects) */
 	int			i;
 
 	/*
-	 * Data proper.  Note that this points just past end of "meta" array.  We
-	 * use its metadata (Jentrys) with JBE_OFF() macro to find appropriate
-	 * offsets into this array.
+	 * Data proper.  This points just past end of children array.
+	 * We use the JBE_OFF() macro on the Jentrys to find offsets of each
+	 * child in this area.
 	 */
 	char	   *dataProper;