Refactoring to RWCursor, RWTxn, and branch/leaf nodes and pages.

1 files changed, 95 insertions, 0 deletions

diff --git a/branch_node.go b/branch_node.go
new file mode 100644
index 0000000..58ab5a5
--- /dev/null
+++ b/branch_node.go
@@ -0,0 +1,95 @@
+package bolt
+
+import (
+	"unsafe"
+)
+
+const (
+	bigNode = 0x01
+	subNode = 0x02
+	dupNode = 0x04
+)
+
+// branchNode represents a node on a branch page.
+type branchNode struct {
+	pgno    uint32
+	flags   uint16
+	keySize uint16
+	data    uintptr // Pointer to the beginning of the data.
+}
+
+// key returns a byte slice that of the key data.
+func (n *branchNode) key() []byte {
+	return (*[MaxKeySize]byte)(unsafe.Pointer(&n.data))[:n.keySize]
+}
+
+func (n *branchNode) size() int {
+	return 0 // TODO: offsetof(MDB_node, mn_data)
+}
+
+// TODO: #define INDXSIZE(k)	 (NODESIZE + ((k) == NULL ? 0 : (k)->mv_size))
+// TODO: #define LEAFSIZE(k, d)	 (NODESIZE + (k)->mv_size + (d)->mv_size)
+// TODO: #define NODEPTR(p, i)	 ((MDB_node *)((char *)(p) + (p)->mp_ptrs[i]))
+// TODO: #define NODEKEY(node)	 (void *)((node)->mn_data)
+// TODO: #define NODEDATA(node)	 (void *)((char *)(node)->mn_data + (node)->mn_ksize)
+// TODO: #define NODEPGNO(node)  ((node)->mn_lo | ((pgno_t) (node)->mn_hi << 16) | (PGNO_TOPWORD ? ((pgno_t) (node)->mn_flags << PGNO_TOPWORD) : 0))
+// TODO: #define SETPGNO(node,pgno)	do { (node)->mn_lo = (pgno) & 0xffff; (node)->mn_hi = (pgno) >> 16; if (PGNO_TOPWORD) (node)->mn_flags = (pgno) >> PGNO_TOPWORD; } while(0)
+// TODO: #define NODEDSZ(node)	 ((node)->mn_lo | ((unsigned)(node)->mn_hi << 16))
+// TODO: #define SETDSZ(node,size)	do { (node)->mn_lo = (size) & 0xffff; (node)->mn_hi = (size) >> 16;} while(0)
+// TODO: #define NODEKSZ(node)	 ((node)->mn_ksize)
+
+// TODO: #define LEAF2KEY(p, i, ks)	((char *)(p) + PAGEHDRSZ + ((i)*(ks)))
+
+// TODO: #define MDB_GET_KEY(node, keyptr)	{ if ((keyptr) != NULL) { (keyptr)->mv_size = NODEKSZ(node); (keyptr)->mv_data = NODEKEY(node); } }
+// TODO: #define MDB_GET_KEY2(node, key)	{ key.mv_size = NODEKSZ(node); key.mv_data = NODEKEY(node); }
+
+// Compact the main page after deleting a node on a subpage.
+// @param[in] mp The main page to operate on.
+// @param[in] indx The index of the subpage on the main page.
+func (n *node) shrink(index int) {
+	/*
+		MDB_node *node;
+		MDB_page *sp, *xp;
+		char *base;
+		int nsize, delta;
+		indx_t		 i, numkeys, ptr;
+
+		node = NODEPTR(mp, indx);
+		sp = (MDB_page *)NODEDATA(node);
+		delta = SIZELEFT(sp);
+		xp = (MDB_page *)((char *)sp + delta);
+
+		// shift subpage upward
+		if (IS_LEAF2(sp)) {
+			nsize = NUMKEYS(sp) * sp->mp_pad;
+			if (nsize & 1)
+				return;		// do not make the node uneven-sized
+			memmove(METADATA(xp), METADATA(sp), nsize);
+		} else {
+			int i;
+			numkeys = NUMKEYS(sp);
+			for (i=numkeys-1; i>=0; i--)
+				xp->mp_ptrs[i] = sp->mp_ptrs[i] - delta;
+		}
+		xp->mp_upper = sp->mp_lower;
+		xp->mp_lower = sp->mp_lower;
+		xp->mp_flags = sp->mp_flags;
+		xp->mp_pad = sp->mp_pad;
+		COPY_PGNO(xp->mp_pgno, mp->mp_pgno);
+
+		nsize = NODEDSZ(node) - delta;
+		SETDSZ(node, nsize);
+
+		// shift lower nodes upward
+		ptr = mp->mp_ptrs[indx];
+		numkeys = NUMKEYS(mp);
+		for (i = 0; i < numkeys; i++) {
+			if (mp->mp_ptrs[i] <= ptr)
+				mp->mp_ptrs[i] += delta;
+		}
+
+		base = (char *)mp + mp->mp_upper;
+		memmove(base + delta, base, ptr - mp->mp_upper + NODESIZE + NODEKSZ(node));
+		mp->mp_upper += delta;
+	*/
+}