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rbt: fix rbtree deletion
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103b1ea560
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@ -27,26 +27,37 @@ func NewRBTree() *RBTree {
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}
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func (tree *RBTree) Delete(key fixedpoint.Value) bool {
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var del = tree.Search(key)
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if del == nil {
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var deleting = tree.Search(key)
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if deleting == nil {
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return false
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}
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// y = the node to be deleted
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// x (the child of the deleted node)
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var x, y *RBNode
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// fmt.Printf("neel = %p %+v\n", tree.neel, tree.neel)
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// fmt.Printf("deleting = %+v\n", deleting)
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if del.Left == tree.neel || del.Right == tree.neel {
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y = del
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// the deleting node has only one child, it's easy,
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// we just connect the child the parent of the deleting node
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if deleting.Left == tree.neel || deleting.Right == tree.neel {
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y = deleting
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// fmt.Printf("y = deleting = %+v\n", y)
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} else {
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y = tree.Successor(del)
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// if both children are not NIL (neel), we need to find the successor
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// and copy the successor to the memory location of the deleting node.
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// since it's successor, it always has no child connecting to it.
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y = tree.Successor(deleting)
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// fmt.Printf("y = successor = %+v\n", y)
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}
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// y.Left or y.Right could be neel
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if y.Left != tree.neel {
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x = y.Left
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} else {
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x = y.Right
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}
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// fmt.Printf("x = %+v\n", y)
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x.Parent = y.Parent
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@ -58,12 +69,14 @@ func (tree *RBTree) Delete(key fixedpoint.Value) bool {
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y.Parent.Right = x
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}
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if y != del {
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del.Key = y.Key
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if y != deleting {
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deleting.Key = y.Key
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}
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if y.Color == Black {
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tree.DeleteFixup(x)
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if x != nil {
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tree.DeleteFixup(x)
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}
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}
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tree.size--
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@ -216,7 +229,7 @@ func (tree *RBTree) Insert(key, val fixedpoint.Value) {
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func (tree *RBTree) Search(key fixedpoint.Value) *RBNode {
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var current = tree.Root
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for current != tree.neel && key != current.Key {
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for current != nil && key != current.Key {
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if key < current.Key {
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current = current.Left
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} else {
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@ -224,11 +237,6 @@ func (tree *RBTree) Search(key fixedpoint.Value) *RBNode {
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}
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}
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// convert Neel to real nil
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if current == tree.neel {
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return nil
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}
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return current
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}
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@ -335,7 +343,7 @@ func (tree *RBTree) Rightmost() *RBNode {
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}
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func (tree *RBTree) RightmostOf(current *RBNode) *RBNode {
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for current.Right != nil {
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for current.Right != tree.neel {
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current = current.Right
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}
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@ -347,7 +355,7 @@ func (tree *RBTree) Leftmost() *RBNode {
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}
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func (tree *RBTree) LeftmostOf(current *RBNode) *RBNode {
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for current.Left != nil {
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for current.Left != tree.neel {
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current = current.Left
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}
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@ -355,12 +363,12 @@ func (tree *RBTree) LeftmostOf(current *RBNode) *RBNode {
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}
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func (tree *RBTree) Successor(current *RBNode) *RBNode {
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if current.Right != nil {
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if current.Right != tree.neel {
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return tree.LeftmostOf(current.Right)
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}
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var newNode = current.Parent
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for newNode != nil && current == newNode.Right {
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for newNode != tree.neel && current == newNode.Right {
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current = newNode
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newNode = newNode.Parent
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}
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@ -12,8 +12,8 @@ func TestTree_InsertAndDelete(t *testing.T) {
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var keys []fixedpoint.Value
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tree := NewRBTree()
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for i := 1; i < 10.0; i++ {
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v := fixedpoint.NewFromFloat(rand.Float64())
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for i := 1; i < 100; i++ {
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v := fixedpoint.NewFromFloat(rand.Float64() * 100 + 1.0)
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keys = append(keys, v)
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tree.Insert(v, fixedpoint.NewFromFloat(float64(i)))
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}
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@ -22,7 +22,6 @@ func TestTree_InsertAndDelete(t *testing.T) {
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ok := tree.Delete(key)
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assert.True(t, ok, "should find and delete the node")
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}
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}
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func TestTree_CopyInorder(t *testing.T) {
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