From b8fe08c765979378d33aff555e2be14705fbdb43 Mon Sep 17 00:00:00 2001
From: Todd Gruben <todd@pilosa.com>
Date: Mon, 13 Jul 2020 20:34:33 -0500
Subject: [PATCH] simplify Walker interface

---
 rbf/cursor_test.go | 17 +++++++++--------
 rbf/cursorx.go     | 18 ++++++++++++------
 2 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/rbf/cursor_test.go b/rbf/cursor_test.go
index f2572c2a0..1fecfbb6c 100644
--- a/rbf/cursor_test.go
+++ b/rbf/cursor_test.go
@@ -822,15 +822,16 @@ func (e *EasyWalker) Visitor(pgno uint32, records []*rbf.RootRecord) {
 func (e *EasyWalker) VisitRoot(pgno uint32, name string) {
 	e.path.WriteString("R")
 }
-func (e *EasyWalker) VisitBranch(pgno uint32) {
-	e.path.WriteString("B")
+func (e *EasyWalker) Visit(pgno uint32, node rbf.Nodetype) {
+	switch node {
+	case rbf.Branch:
+		e.path.WriteString("B")
+	case rbf.Leaf:
+		e.path.WriteString("L")
+	case rbf.Bitmap:
+		e.path.WriteString("b")
+	}
 
-}
-func (e *EasyWalker) VisitLeaf(pgno uint32) {
-	e.path.WriteString("L")
-
-}
-func (e *EasyWalker) VisitBitmap(pgno uint32) {
 }
 func (e *EasyWalker) String() string {
 	return e.path.String()
diff --git a/rbf/cursorx.go b/rbf/cursorx.go
index 366d44b00..343960a2b 100644
--- a/rbf/cursorx.go
+++ b/rbf/cursorx.go
@@ -139,12 +139,18 @@ func toContainer(l leafCell) *roaring.Container {
 	return nil
 }
 
+type Nodetype int
+
+const (
+	Branch Nodetype = iota
+	Leaf
+	Bitmap
+)
+
 type Walker interface {
 	Visitor(pgno uint32, records []*RootRecord)
 	VisitRoot(pgno uint32, name string)
-	VisitBranch(pgno uint32)
-	VisitLeaf(pgno uint32)
-	VisitBitmap(pgno uint32)
+	Visit(pgno uint32, n Nodetype)
 }
 
 func Page(tx *Tx, pgno uint32, walker Walker) {
@@ -161,17 +167,17 @@ func Page(tx *Tx, pgno uint32, walker Walker) {
 	// Handle
 	switch typ := readFlags(page); typ {
 	case PageTypeBranch:
-		walker.VisitBranch(pgno)
+		walker.Visit(pgno, Branch)
 		for i, n := 0, readCellN(page); i < n; i++ {
 			cell := readBranchCell(page, i)
 			if cell.Flags&ContainerTypeBitmap == 0 { // leaf/branch child page
 				Page(tx, cell.Pgno, walker)
 			} else {
-				walker.VisitBitmap(cell.Pgno)
+				walker.Visit(cell.Pgno, Bitmap)
 			}
 		}
 	case PageTypeLeaf:
-		walker.VisitLeaf(pgno)
+		walker.Visit(pgno, Leaf)
 	default:
 		panic(err)
 	}