Start rendering and testing

btree/btree_test.go

@@ -0,0 +1,25 @@
+package btree
+
+import (
+	"fmt"
+	"testing"
+)
+
+func intCmp(a, b int) int {
+	return a - b
+}
+
+func TestBasic(t *testing.T) {
+	bt := NewWithTee[int, string](intCmp, 4)
+	bt.Insert(2, "two")
+	bt.Insert(4, "four")
+	bt.Insert(1, "one")
+	bt.Insert(7, "seven")
+	bt.Insert(6, "six")
+	bt.Insert(3, "three")
+	bt.Insert(11, "eleven")
+	bt.Insert(9, "nine")
+	bt.Insert(21, "twentyone")
+
+	fmt.Println(bt.renderDot())
+}

btree/dot.go

@@ -0,0 +1,53 @@
+package btree
+
+import (
+	"fmt"
+	"iter"
+	"strings"
+)
+
+const prefix = `digraph g {
+node [shape = record,height=0.1];
+`
+
+func (bt *BTree[K, V]) renderDot() string {
+	nodeNames := make(map[*node[K, V]]string)
+	nodeNumber := 0
+
+	node2name := func(n *node[K, V]) string {
+		if name, ok := nodeNames[n]; ok {
+			return name
+		}
+		nodeNames[n] = fmt.Sprintf("node%d", nodeNumber)
+		nodeNumber++
+		return nodeNames[n]
+	}
+
+	// TODO: continue here, emit node contents followed by child pointers
+	var sb strings.Builder
+	sb.WriteString(prefix)
+	for n := range bt.nodesPreOrder() {
+		sb.WriteString(fmt.Sprintf("%s\n", node2name(n)))
+	}
+	sb.WriteString("}\n")
+
+	return sb.String()
+}
+
+func (bt *BTree[K, V]) nodesPreOrder() iter.Seq[*node[K, V]] {
+	return func(yield func(*node[K, V]) bool) {
+		bt.pushPreOrder(yield, bt.root)
+	}
+}
+
+func (bt *BTree[K, V]) pushPreOrder(yield func(*node[K, V]) bool, n *node[K, V]) bool {
+	if !yield(n) {
+		return false
+	}
+	for _, c := range n.children {
+		if !bt.pushPreOrder(yield, c) {
+			return false
+		}
+	}
+	return true
+}