1 package unstable
2
3
4
5
6 type root struct {
7 nodes []Node
8 }
9
10
11 func (r *root) Iterator() Iterator {
12 it := Iterator{}
13 if len(r.nodes) > 0 {
14 it.node = &r.nodes[0]
15 }
16 return it
17 }
18
19 func (r *root) at(idx reference) *Node {
20 return &r.nodes[idx]
21 }
22
23 type reference int
24
25 const invalidReference reference = -1
26
27 func (r reference) Valid() bool {
28 return r != invalidReference
29 }
30
31 type builder struct {
32 tree root
33 lastIdx int
34 }
35
36 func (b *builder) Tree() *root {
37 return &b.tree
38 }
39
40 func (b *builder) NodeAt(ref reference) *Node {
41 return b.tree.at(ref)
42 }
43
44 func (b *builder) Reset() {
45 b.tree.nodes = b.tree.nodes[:0]
46 b.lastIdx = 0
47 }
48
49 func (b *builder) Push(n Node) reference {
50 b.lastIdx = len(b.tree.nodes)
51 b.tree.nodes = append(b.tree.nodes, n)
52 return reference(b.lastIdx)
53 }
54
55 func (b *builder) PushAndChain(n Node) reference {
56 newIdx := len(b.tree.nodes)
57 b.tree.nodes = append(b.tree.nodes, n)
58 if b.lastIdx >= 0 {
59 b.tree.nodes[b.lastIdx].next = newIdx - b.lastIdx
60 }
61 b.lastIdx = newIdx
62 return reference(b.lastIdx)
63 }
64
65 func (b *builder) AttachChild(parent reference, child reference) {
66 b.tree.nodes[parent].child = int(child) - int(parent)
67 }
68
69 func (b *builder) Chain(from reference, to reference) {
70 b.tree.nodes[from].next = int(to) - int(from)
71 }
72
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