runxiyu.tngl.sh
Fast implementation of Git in pure Go
1package read
2
3import "codeberg.org/lindenii/furgit/commitgraph"
4
5// ParentRef references one parent position.
6type ParentRef struct {
7 Valid bool
8 Pos Position
9}
10
11func (reader *Reader) decodeParents(layer *layer, p1, p2 uint32) (ParentRef, ParentRef, []Position, error) {
12 parent1, err := reader.decodeSingleParent(p1)
13 if err != nil {
14 return ParentRef{}, ParentRef{}, nil, err
15 }
16
17 if p2 == commitgraph.ParentNone {
18 return parent1, ParentRef{}, nil, nil
19 }
20
21 if p2&commitgraph.ParentExtraMask == 0 {
22 parent2, err := reader.decodeSingleParent(p2)
23 if err != nil {
24 return ParentRef{}, ParentRef{}, nil, err
25 }
26
27 return parent1, parent2, nil, nil
28 }
29
30 edgeStart := p2 & commitgraph.ParentLastMask
31
32 parents, err := reader.decodeExtraEdgeList(layer, edgeStart)
33 if err != nil {
34 return ParentRef{}, ParentRef{}, nil, err
35 }
36
37 if len(parents) == 0 {
38 return ParentRef{}, ParentRef{}, nil, &MalformedError{Path: layer.path, Reason: "empty EDGE list"}
39 }
40
41 parent2 := ParentRef{Valid: true, Pos: parents[0]}
42 if len(parents) == 1 {
43 return parent1, parent2, nil, nil
44 }
45
46 return parent1, parent2, parents[1:], nil
47}
48
49func (reader *Reader) decodeSingleParent(raw uint32) (ParentRef, error) {
50 if raw == commitgraph.ParentNone {
51 return ParentRef{}, nil
52 }
53
54 if raw&commitgraph.ParentExtraMask != 0 {
55 return ParentRef{}, &MalformedError{
56 Path: "commit-graph",
57 Reason: "unexpected EDGE marker in single-parent slot",
58 }
59 }
60
61 pos, err := reader.globalToPosition(raw)
62 if err != nil {
63 return ParentRef{}, err
64 }
65
66 return ParentRef{Valid: true, Pos: pos}, nil
67}