forked from alecthomas/gometalinter
-
Notifications
You must be signed in to change notification settings - Fork 0
/
syntax.go
175 lines (156 loc) · 3.47 KB
/
syntax.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
package syntax
import (
"crypto/sha1"
"github.com/mibk/dupl/suffixtree"
)
type Node struct {
Type int
Filename string
Pos, End int
Children []*Node
Owns int
}
func NewNode() *Node {
return &Node{}
}
func (n *Node) AddChildren(children ...*Node) {
n.Children = append(n.Children, children...)
}
func (n *Node) Val() int {
return n.Type
}
type Match struct {
Hash string
Frags [][]*Node
}
func Serialize(n *Node) []*Node {
stream := make([]*Node, 0, 10)
serial(n, &stream)
return stream
}
func serial(n *Node, stream *[]*Node) int {
*stream = append(*stream, n)
var count int
for _, child := range n.Children {
count += serial(child, stream)
}
n.Owns = count
return count + 1
}
// FindSyntaxUnits finds all complete syntax units in the match group and returns them
// with the corresponding hash.
func FindSyntaxUnits(data []*Node, m suffixtree.Match, threshold int) Match {
if len(m.Ps) == 0 {
return Match{}
}
firstSeq := data[m.Ps[0] : m.Ps[0]+m.Len]
indexes := getUnitsIndexes(firstSeq, threshold)
// TODO: is this really working?
indexCnt := len(indexes)
if indexCnt > 0 {
lasti := indexes[indexCnt-1]
firstn := firstSeq[lasti]
for i := 1; i < len(m.Ps); i++ {
n := data[int(m.Ps[i])+lasti]
if firstn.Owns != n.Owns {
indexes = indexes[:indexCnt-1]
break
}
}
}
if len(indexes) == 0 || isCyclic(indexes, firstSeq) || spansMultipleFiles(indexes, firstSeq) {
return Match{}
}
match := Match{Frags: make([][]*Node, len(m.Ps))}
for i, pos := range m.Ps {
match.Frags[i] = make([]*Node, len(indexes))
for j, index := range indexes {
match.Frags[i][j] = data[int(pos)+index]
}
}
lastIndex := indexes[len(indexes)-1]
match.Hash = hashSeq(firstSeq[indexes[0] : lastIndex+firstSeq[lastIndex].Owns])
return match
}
func getUnitsIndexes(nodeSeq []*Node, threshold int) []int {
var indexes []int
var split bool
for i := 0; i < len(nodeSeq); {
n := nodeSeq[i]
switch {
case n.Owns >= len(nodeSeq)-i:
// not complete syntax unit
i++
split = true
continue
case n.Owns+1 < threshold:
split = true
default:
if split {
indexes = indexes[:0]
split = false
}
indexes = append(indexes, i)
}
i += n.Owns + 1
}
return indexes
}
// isCyclic finds out whether there is a repetive pattern in the found clone. If positive,
// it return false to point out that the clone would be redundant.
func isCyclic(indexes []int, nodes []*Node) bool {
cnt := len(indexes)
if cnt <= 1 {
return false
}
alts := make(map[int]bool)
for i := 1; i <= cnt/2; i++ {
if cnt%i == 0 {
alts[i] = true
}
}
for i := 0; i < indexes[cnt/2]; i++ {
nstart := nodes[i+indexes[0]]
AltLoop:
for alt := range alts {
for j := alt; j < cnt; j += alt {
index := i + indexes[j]
if index < len(nodes) {
nalt := nodes[index]
if nstart.Owns == nalt.Owns && nstart.Type == nalt.Type {
continue
}
} else if i >= indexes[alt] {
return true
}
delete(alts, alt)
continue AltLoop
}
}
if len(alts) == 0 {
return false
}
}
return true
}
func spansMultipleFiles(indexes []int, nodes []*Node) bool {
if len(indexes) < 2 {
return false
}
f := nodes[indexes[0]].Filename
for i := 1; i < len(indexes); i++ {
if nodes[indexes[i]].Filename != f {
return true
}
}
return false
}
func hashSeq(nodes []*Node) string {
h := sha1.New()
bytes := make([]byte, len(nodes))
for i, node := range nodes {
bytes[i] = byte(node.Type)
}
h.Write(bytes)
return string(h.Sum(nil))
}