/
label.go
324 lines (288 loc) · 7.11 KB
/
label.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
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
package label
import (
"encoding"
"errors"
"strings"
"github.com/blang/semver"
)
// A Label represents a parsed label.
//
// The general form represented is:
//
// [kind:][[module[+version]@][//]package][:name]
//
// If the package is omitted and the name is present, the label is relative to the
// current package.
type Label struct {
Kind string
Module string
Version *semver.Version
Package string
Name string
}
var _ encoding.TextMarshaler = (*Label)(nil)
var _ encoding.TextUnmarshaler = (*Label)(nil)
// Parse parses rawlabel into a Label structure.
func Parse(rawlabel string) (*Label, error) {
nameColon := strings.LastIndexByte(rawlabel, ':')
if nameColon == -1 {
nameColon = len(rawlabel)
}
kindModuleAndPkg := rawlabel[:nameColon]
kind, moduleAndPkg := "", ""
if kindColon := strings.IndexByte(kindModuleAndPkg, ':'); kindColon != -1 {
kind, moduleAndPkg = kindModuleAndPkg[:kindColon], kindModuleAndPkg[kindColon+1:]
} else {
moduleAndPkg = kindModuleAndPkg
}
module, version, pkg := "", (*semver.Version)(nil), ""
if moduleAt := strings.IndexByte(moduleAndPkg, '@'); moduleAt != -1 && !strings.HasPrefix(moduleAndPkg, "//") {
module, pkg = moduleAndPkg[:moduleAt], moduleAndPkg[moduleAt+1:]
if versionPlus := strings.IndexByte(module, '+'); versionPlus != -1 {
v, err := semver.ParseTolerant(module[versionPlus+1:])
if err != nil {
return nil, err
}
module, version = module[:versionPlus], &v
}
} else {
pkg = moduleAndPkg
}
pkg, err := Clean(pkg)
if err != nil {
return nil, err
}
name := ""
if nameColon < len(rawlabel) {
name = rawlabel[nameColon+1:]
if strings.ContainsRune(name, '/') {
return nil, errors.New("names may not contain ':' or '/'")
}
}
l := &Label{
Kind: kind,
Module: module,
Version: version,
Package: pkg,
Name: name,
}
if module != "" && !l.IsAbs() {
return nil, errors.New("labels with modules must be absolute")
}
return l, nil
}
func New(kind, module, pkg, name string) (*Label, error) {
if strings.ContainsAny(kind, ":/") {
return nil, errors.New("kind may not contain ':' or '/'")
}
pkg, err := Clean(pkg)
if err != nil {
return nil, err
}
if strings.ContainsAny(name, ":/") {
return nil, errors.New("name may not contain ':' or '/'")
}
return &Label{Kind: kind, Module: module, Package: pkg, Name: name}, nil
}
func (l *Label) MarshalText() ([]byte, error) {
return []byte(l.String()), nil
}
func (l *Label) UnmarshalText(text []byte) error {
ll, err := Parse(string(text))
if err != nil {
return err
}
*l = *ll
return nil
}
func (l *Label) IsAbs() bool {
return strings.HasPrefix(l.Package, "//")
}
func (l *Label) RelativeTo(pkg string) (*Label, error) {
if l.IsAbs() {
return l, nil
}
pkg, err := Join(pkg, l.Package)
if err != nil {
return nil, err
}
return &Label{
Kind: l.Kind,
Module: l.Module,
Version: l.Version,
Package: pkg,
Name: l.Name,
}, nil
}
func (l *Label) String() string {
var b strings.Builder
if l.Kind != "" {
b.WriteString(l.Kind)
b.WriteRune(':')
}
if l.Module != "" {
b.WriteString(l.Module)
if l.Version != nil {
b.WriteRune('+')
b.WriteString(l.Version.String())
}
b.WriteRune('@')
}
b.WriteString(l.Package)
if l.Name != "" {
b.WriteRune(':')
b.WriteString(l.Name)
}
return b.String()
}
// A lazybuf is a lazily constructed path buffer.
// It supports append, reading previously appended bytes,
// and retrieving the final string. It does not allocate a buffer
// to hold the output until that output diverges from s.
type lazybuf struct {
s string
buf []byte
w int
}
func (b *lazybuf) index(i int) byte {
if b.buf != nil {
return b.buf[i]
}
return b.s[i]
}
func (b *lazybuf) append(c byte) {
if b.buf == nil {
if b.w < len(b.s) && b.s[b.w] == c {
b.w++
return
}
b.buf = make([]byte, len(b.s))
copy(b.buf, b.s[:b.w])
}
b.buf[b.w] = c
b.w++
}
func (b *lazybuf) string() string {
if b.buf == nil {
return b.s[:b.w]
}
return string(b.buf[:b.w])
}
// Clean returns the shortest pkg name equivalent to pkg and checks
// the pkg path for errors. It replaces multiple slashes with a single
// slash and rejects pkg paths that contain colons, '..' or '.' elements.
func Clean(pkg string) (string, error) {
if pkg == "" {
return "", nil
}
rooted := len(pkg) >= 2 && pkg[0] == '/' && pkg[1] == '/'
n := len(pkg)
// Invariants:
// reading from pkg; r is index of next byte to process.
// writing to buf; w is index of next byte to write.
// dotdot is index in buf where .. must stop, either because
// it is the leading slash or it is a leading ../../.. prefix.
out := lazybuf{s: pkg}
r := 0
if rooted {
out.append('/')
out.append('/')
r = 2
}
if !rooted && pkg[r] == '/' {
return "", errors.New("absolute pkg paths must begin with '//'")
}
for r < n {
switch {
case pkg[r] == ':':
return "", errors.New("pkg paths may not contain ':'")
case pkg[r] == '/':
// empty pkg element
r++
case pkg[r] == '.' && (r+1 == n || pkg[r+1] == '/'):
return "", errors.New("pkg paths may not contain '.' or '..' elements")
case pkg[r] == '.' && pkg[r+1] == '.' && (r+2 == n || pkg[r+2] == '/'):
return "", errors.New("pkg paths may not contain '.' or '..' elements")
default:
// real pkg element.
// add slash if needed
if rooted && out.w != 2 || !rooted && out.w != 0 {
out.append('/')
}
// copy element
for ; r < n && pkg[r] != '/' && pkg[r] != ':'; r++ {
out.append(pkg[r])
}
}
}
return out.string(), nil
}
// Parent returns the parent of pkg.
func Parent(pkg string) string {
raw, adjust := pkg, 0
if strings.HasPrefix(pkg, "//") {
pkg, adjust = pkg[2:], 2
}
lastSlash := strings.LastIndexByte(pkg, '/')
if lastSlash == -1 {
return raw[:adjust]
}
return raw[:lastSlash+adjust]
}
// Dir returns the last component of pkg.
func Dir(pkg string) string {
if strings.HasPrefix(pkg, "//") {
pkg = pkg[2:]
}
lastSlash := strings.LastIndexByte(pkg, '/')
if lastSlash == -1 {
return pkg
}
return pkg[lastSlash+1:]
}
// Split splits a package path into its components. If the path is absolute, the first
// component will be "//". Multiple slashes separating components are treated as a single
// slash.
func Split(pkg string) []string {
var components []string
i := 0
if strings.HasPrefix(pkg, "//") {
components, pkg = append(components, "//"), pkg[2:]
}
for i < len(pkg) {
switch {
case pkg[i] == '/':
i++
default:
start := i
for ; i < len(pkg) && pkg[i] != '/'; i++ {
}
components = append(components, pkg[start:i])
}
}
return components
}
// Join joins any number of path elements into a single path,
// separating them with slashes. Empty elements are ignored.
// The result is Cleaned. However, if the argument list is
// empty or all its elements are empty, Join returns
// an empty string.
func Join(elem ...string) (string, error) {
size := 0
for _, e := range elem {
size += len(e)
}
if size == 0 {
return "", nil
}
buf := make([]byte, 0, size+len(elem)-1)
for _, e := range elem {
if len(buf) > 0 || e != "" {
if len(buf) > 0 {
buf = append(buf, '/')
}
buf = append(buf, e...)
}
}
return Clean(string(buf))
}