forked from kubernetes/kubernetes
-
Notifications
You must be signed in to change notification settings - Fork 0
/
selector.go
343 lines (302 loc) · 9.35 KB
/
selector.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
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
/*
Copyright 2014 Google Inc. All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package labels
import (
"bytes"
"fmt"
"sort"
"strings"
"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
)
// Selector represents a label selector.
type Selector interface {
// Matches returns true if this selector matches the given set of labels.
Matches(Labels) bool
// Empty returns true if this selector does not restrict the selection space.
Empty() bool
// RequiresExactMatch allows a caller to introspect whether a given selector
// requires a single specific label to be set, and if so returns the value it
// requires.
// TODO: expand this to be more general
RequiresExactMatch(label string) (value string, found bool)
// String returns a human readable string that represents this selector.
String() string
}
// Everything returns a selector that matches all labels.
func Everything() Selector {
return andTerm{}
}
type hasTerm struct {
label, value string
}
func (t *hasTerm) Matches(ls Labels) bool {
return ls.Get(t.label) == t.value
}
func (t *hasTerm) Empty() bool {
return false
}
func (t *hasTerm) RequiresExactMatch(label string) (value string, found bool) {
if t.label == label {
return t.value, true
}
return "", false
}
func (t *hasTerm) String() string {
return fmt.Sprintf("%v=%v", t.label, t.value)
}
type notHasTerm struct {
label, value string
}
func (t *notHasTerm) Matches(ls Labels) bool {
return ls.Get(t.label) != t.value
}
func (t *notHasTerm) Empty() bool {
return false
}
func (t *notHasTerm) RequiresExactMatch(label string) (value string, found bool) {
return "", false
}
func (t *notHasTerm) String() string {
return fmt.Sprintf("%v!=%v", t.label, t.value)
}
type andTerm []Selector
func (t andTerm) Matches(ls Labels) bool {
for _, q := range t {
if !q.Matches(ls) {
return false
}
}
return true
}
func (t andTerm) Empty() bool {
if t == nil {
return true
}
if len([]Selector(t)) == 0 {
return true
}
for i := range t {
if !t[i].Empty() {
return false
}
}
return true
}
func (t andTerm) RequiresExactMatch(label string) (string, bool) {
if t == nil || len([]Selector(t)) == 0 {
return "", false
}
for i := range t {
if value, found := t[i].RequiresExactMatch(label); found {
return value, found
}
}
return "", false
}
func (t andTerm) String() string {
var terms []string
for _, q := range t {
terms = append(terms, q.String())
}
return strings.Join(terms, ",")
}
// Operator represents a key's relationship
// to a set of values in a Requirement.
type Operator int
const (
In Operator = iota + 1
NotIn
Exists
)
// LabelSelector contains a list of Requirements.
// LabelSelector is set-based and is distinguished from exact
// match-based selectors composed of key=value matching conjunctions.
// TODO: Remove previous sentence when exact match-based
// selectors are removed.
type LabelSelector struct {
Requirements []Requirement
}
// Requirement is a selector that contains values, a key
// and an operator that relates the key and values. The zero
// value of Requirement is invalid. See the NewRequirement
// constructor for creating a valid Requirement.
// Requirement is set-based and is distinguished from exact
// match-based selectors composed of key=value matching.
// TODO: Remove previous sentence when exact match-based
// selectors are removed.
type Requirement struct {
key string
operator Operator
strValues util.StringSet
}
// NewRequirement is the constructor for a Requirement.
// If either of these rules is violated, an error is returned:
// (1) The operator can only be In, NotIn or Exists.
// (2) If the operator is In or NotIn, the values set must
// be non-empty.
//
// The empty string is a valid value in the input values set.
func NewRequirement(key string, op Operator, vals util.StringSet) (*Requirement, error) {
switch op {
case In, NotIn:
if len(vals) == 0 {
return nil, fmt.Errorf("for In,NotIn operators, values set can't be empty")
}
case Exists:
default:
return nil, fmt.Errorf("operator '%v' is not recognized", op)
}
return &Requirement{key: key, operator: op, strValues: vals}, nil
}
// Matches returns true if the Requirement matches the input Labels.
// There is a match in the following cases:
// (1) The operator is Exists and Labels has the Requirement's key.
// (2) The operator is In, Labels has the Requirement's key and Labels'
// value for that key is in Requirement's value set.
// (3) The operator is NotIn, Labels has the Requirement's key and
// Labels' value for that key is not in Requirement's value set.
// (4) The operator is NotIn and Labels does not have the
// Requirement's key.
//
// If called on an invalid Requirement, an error is returned. See
// NewRequirement for creating a valid Requirement.
func (r *Requirement) Matches(ls Labels) (bool, error) {
switch r.operator {
case In:
if !ls.Has(r.key) {
return false, nil
}
return r.strValues.Has(ls.Get(r.key)), nil
case NotIn:
if !ls.Has(r.key) {
return true, nil
}
return !r.strValues.Has(ls.Get(r.key)), nil
case Exists:
return ls.Has(r.key), nil
default:
return false, fmt.Errorf("requirement is not set: %+v", r)
}
}
// String returns a human-readable string that represents this
// Requirement. If called on an invalid Requirement, an error is
// returned. See NewRequirement for creating a valid Requirement.
func (r *Requirement) String() (string, error) {
var buffer bytes.Buffer
buffer.WriteString(r.key)
switch r.operator {
case In:
buffer.WriteString(" in ")
case NotIn:
buffer.WriteString(" not in ")
case Exists:
return buffer.String(), nil
default:
return "", fmt.Errorf("requirement is not set: %+v", r)
}
buffer.WriteString("(")
if len(r.strValues) == 1 {
buffer.WriteString(r.strValues.List()[0])
} else { // only > 1 since == 0 prohibited by NewRequirement
buffer.WriteString(strings.Join(r.strValues.List(), ","))
}
buffer.WriteString(")")
return buffer.String(), nil
}
// Matches for a LabelSelector returns true if all
// its Requirements match the input Labels. If any
// Requirement does not match, false is returned.
// An error is returned if any match attempt between
// a Requirement and the input Labels returns an error.
func (lsel *LabelSelector) Matches(l Labels) (bool, error) {
for _, req := range lsel.Requirements {
if matches, err := req.Matches(l); err != nil {
return false, err
} else if !matches {
return false, nil
}
}
return true, nil
}
// String returns a comma-separated string of all
// the LabelSelector Requirements' human-readable strings.
// An error is returned if any attempt to get a
// Requirement's human-readable string returns an error.
func (lsel *LabelSelector) String() (string, error) {
var reqs []string
for _, req := range lsel.Requirements {
if str, err := req.String(); err != nil {
return "", err
} else {
reqs = append(reqs, str)
}
}
return strings.Join(reqs, ","), nil
}
// TODO: Parse takes a string representing a selector and returns
// a selector, or an error. A well-formed input string follows
// the syntax of that which is returned by LabelSelector.String
// and therefore is largely controlled by that which is returned
// by Requirement.String. The returned selector object's type
// should be an interface implemented by LabelSelector. Note that
// this parsing function is different than ParseSelector since
// they parse different selectors with different syntaxes.
// See comments above for LabelSelector and Requirement struct
// definition for more details.
func try(selectorPiece, op string) (lhs, rhs string, ok bool) {
pieces := strings.Split(selectorPiece, op)
if len(pieces) == 2 {
return pieces[0], pieces[1], true
}
return "", "", false
}
// SelectorFromSet returns a Selector which will match exactly the given Set. A
// nil Set is considered equivalent to Everything().
func SelectorFromSet(ls Set) Selector {
if ls == nil {
return Everything()
}
items := make([]Selector, 0, len(ls))
for label, value := range ls {
items = append(items, &hasTerm{label: label, value: value})
}
if len(items) == 1 {
return items[0]
}
return andTerm(items)
}
// ParseSelector takes a string representing a selector and returns an
// object suitable for matching, or an error.
func ParseSelector(selector string) (Selector, error) {
parts := strings.Split(selector, ",")
sort.StringSlice(parts).Sort()
var items []Selector
for _, part := range parts {
if part == "" {
continue
}
if lhs, rhs, ok := try(part, "!="); ok {
items = append(items, ¬HasTerm{label: lhs, value: rhs})
} else if lhs, rhs, ok := try(part, "=="); ok {
items = append(items, &hasTerm{label: lhs, value: rhs})
} else if lhs, rhs, ok := try(part, "="); ok {
items = append(items, &hasTerm{label: lhs, value: rhs})
} else {
return nil, fmt.Errorf("invalid selector: '%s'; can't understand '%s'", selector, part)
}
}
if len(items) == 1 {
return items[0], nil
}
return andTerm(items), nil
}