rbt: fix deleting, copy value to the deleting node's memory

pkg/types/rbtree.go

@@ -57,8 +57,8 @@ func (tree *RBTree) Delete(key fixedpoint.Value) bool {
 	} else {
 		x = y.Right
 	}
-	// fmt.Printf("x = %+v\n", y)
 
+	// fmt.Printf("x = %+v\n", y)
 	x.Parent = y.Parent
 
 	if y.Parent == tree.neel {
@@ -69,14 +69,14 @@ func (tree *RBTree) Delete(key fixedpoint.Value) bool {
 		y.Parent.Right = x
 	}
 
+	// copy the data from the successor to the memory location of the deleting node
 	if y != deleting {
 		deleting.Key = y.Key
+		deleting.Value = y.Value
 	}
 
 	if y.Color == Black {
-		if x != nil {
-			tree.DeleteFixup(x)
-		}
+		tree.DeleteFixup(x)
 	}
 
 	tree.size--

pkg/types/rbtree_test.go

@@ -8,12 +8,42 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestTree_InsertAndDelete(t *testing.T) {
+func TestRBTree_InsertAndDelete(t *testing.T) {
+	tree := NewRBTree()
+	tree.Insert(fixedpoint.NewFromInt(10), 10)
+	tree.Insert(fixedpoint.NewFromInt(9), 9)
+	tree.Insert(fixedpoint.NewFromInt(12), 12)
+	tree.Insert(fixedpoint.NewFromInt(11), 11)
+	tree.Insert(fixedpoint.NewFromInt(13), 13)
+
+	node := tree.Rightmost()
+	assert.Equal(t, fixedpoint.NewFromInt(13), node.Key)
+
+	ok := tree.Delete(fixedpoint.NewFromInt(12))
+	assert.True(t, ok, "should delete the node successfully")
+}
+
+func TestRBTree_Rightmost(t *testing.T) {
+	tree := NewRBTree()
+	node := tree.Rightmost()
+	assert.Nil(t, node, "should be nil")
+
+	tree.Insert(10, 10)
+	node = tree.Rightmost()
+	assert.Equal(t, fixedpoint.Value(10), node.Key)
+
+	tree.Insert(12, 12)
+	tree.Insert(9, 9)
+	node = tree.Rightmost()
+	assert.Equal(t, fixedpoint.Value(12), node.Key)
+}
+
+func TestRBTree_RandomInsertAndDelete(t *testing.T) {
 	var keys []fixedpoint.Value
 
 	tree := NewRBTree()
 	for i := 1; i < 100; i++ {
-		v := fixedpoint.NewFromFloat(rand.Float64() * 100 + 1.0)
+		v := fixedpoint.NewFromFloat(rand.Float64()*100 + 1.0)
 		keys = append(keys, v)
 		tree.Insert(v, fixedpoint.NewFromFloat(float64(i)))
 	}
@@ -24,7 +54,7 @@ func TestTree_InsertAndDelete(t *testing.T) {
 	}
 }
 
-func TestTree_CopyInorder(t *testing.T) {
+func TestRBTree_CopyInorder(t *testing.T) {
 	tree := NewRBTree()
 	for i := 1.0; i < 10.0; i += 1.0 {
 		tree.Insert(fixedpoint.NewFromFloat(i*100.0), fixedpoint.NewFromFloat(i))