This repository has been archived by the owner on Oct 11, 2018. It is now read-only.
-
Notifications
You must be signed in to change notification settings - Fork 695
/
structs.go
584 lines (490 loc) · 14.9 KB
/
structs.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
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
// Package structs contains various utilities functions to work with structs.
package structs
import (
"fmt"
"reflect"
)
var (
// DefaultTagName is the default tag name for struct fields which provides
// a more granular to tweak certain structs. Lookup the necessary functions
// for more info.
DefaultTagName = "structs" // struct's field default tag name
)
// Struct encapsulates a struct type to provide several high level functions
// around the struct.
type Struct struct {
raw interface{}
value reflect.Value
TagName string
}
// New returns a new *Struct with the struct s. It panics if the s's kind is
// not struct.
func New(s interface{}) *Struct {
return &Struct{
raw: s,
value: strctVal(s),
TagName: DefaultTagName,
}
}
// Map converts the given struct to a map[string]interface{}, where the keys
// of the map are the field names and the values of the map the associated
// values of the fields. The default key string is the struct field name but
// can be changed in the struct field's tag value. The "structs" key in the
// struct's field tag value is the key name. Example:
//
// // Field appears in map as key "myName".
// Name string `structs:"myName"`
//
// A tag value with the content of "-" ignores that particular field. Example:
//
// // Field is ignored by this package.
// Field bool `structs:"-"`
//
// A tag value with the content of "string" uses the stringer to get the value. Example:
//
// // The value will be output of Animal's String() func.
// // Map will panic if Animal does not implement String().
// Field *Animal `structs:"field,string"`
//
// A tag value with the option of "flatten" used in a struct field is to flatten its fields
// in the output map. Example:
//
// // The FieldStruct's fields will be flattened into the output map.
// FieldStruct time.Time `structs:",flatten"`
//
// A tag value with the option of "omitnested" stops iterating further if the type
// is a struct. Example:
//
// // Field is not processed further by this package.
// Field time.Time `structs:"myName,omitnested"`
// Field *http.Request `structs:",omitnested"`
//
// A tag value with the option of "omitempty" ignores that particular field if
// the field value is empty. Example:
//
// // Field appears in map as key "myName", but the field is
// // skipped if empty.
// Field string `structs:"myName,omitempty"`
//
// // Field appears in map as key "Field" (the default), but
// // the field is skipped if empty.
// Field string `structs:",omitempty"`
//
// Note that only exported fields of a struct can be accessed, non exported
// fields will be neglected.
func (s *Struct) Map() map[string]interface{} {
out := make(map[string]interface{})
s.FillMap(out)
return out
}
// FillMap is the same as Map. Instead of returning the output, it fills the
// given map.
func (s *Struct) FillMap(out map[string]interface{}) {
if out == nil {
return
}
fields := s.structFields()
for _, field := range fields {
name := field.Name
val := s.value.FieldByName(name)
isSubStruct := false
var finalVal interface{}
tagName, tagOpts := parseTag(field.Tag.Get(s.TagName))
if tagName != "" {
name = tagName
}
// if the value is a zero value and the field is marked as omitempty do
// not include
if tagOpts.Has("omitempty") {
zero := reflect.Zero(val.Type()).Interface()
current := val.Interface()
if reflect.DeepEqual(current, zero) {
continue
}
}
if !tagOpts.Has("omitnested") {
finalVal = s.nested(val)
v := reflect.ValueOf(val.Interface())
if v.Kind() == reflect.Ptr {
v = v.Elem()
}
switch v.Kind() {
case reflect.Map, reflect.Struct:
isSubStruct = true
}
} else {
finalVal = val.Interface()
}
if tagOpts.Has("string") {
s, ok := val.Interface().(fmt.Stringer)
if ok {
out[name] = s.String()
}
continue
}
if isSubStruct && (tagOpts.Has("flatten")) {
for k := range finalVal.(map[string]interface{}) {
out[k] = finalVal.(map[string]interface{})[k]
}
} else {
out[name] = finalVal
}
}
}
// Values converts the given s struct's field values to a []interface{}. A
// struct tag with the content of "-" ignores the that particular field.
// Example:
//
// // Field is ignored by this package.
// Field int `structs:"-"`
//
// A value with the option of "omitnested" stops iterating further if the type
// is a struct. Example:
//
// // Fields is not processed further by this package.
// Field time.Time `structs:",omitnested"`
// Field *http.Request `structs:",omitnested"`
//
// A tag value with the option of "omitempty" ignores that particular field and
// is not added to the values if the field value is empty. Example:
//
// // Field is skipped if empty
// Field string `structs:",omitempty"`
//
// Note that only exported fields of a struct can be accessed, non exported
// fields will be neglected.
func (s *Struct) Values() []interface{} {
fields := s.structFields()
var t []interface{}
for _, field := range fields {
val := s.value.FieldByName(field.Name)
_, tagOpts := parseTag(field.Tag.Get(s.TagName))
// if the value is a zero value and the field is marked as omitempty do
// not include
if tagOpts.Has("omitempty") {
zero := reflect.Zero(val.Type()).Interface()
current := val.Interface()
if reflect.DeepEqual(current, zero) {
continue
}
}
if tagOpts.Has("string") {
s, ok := val.Interface().(fmt.Stringer)
if ok {
t = append(t, s.String())
}
continue
}
if IsStruct(val.Interface()) && !tagOpts.Has("omitnested") {
// look out for embedded structs, and convert them to a
// []interface{} to be added to the final values slice
t = append(t, Values(val.Interface())...)
} else {
t = append(t, val.Interface())
}
}
return t
}
// Fields returns a slice of Fields. A struct tag with the content of "-"
// ignores the checking of that particular field. Example:
//
// // Field is ignored by this package.
// Field bool `structs:"-"`
//
// It panics if s's kind is not struct.
func (s *Struct) Fields() []*Field {
return getFields(s.value, s.TagName)
}
// Names returns a slice of field names. A struct tag with the content of "-"
// ignores the checking of that particular field. Example:
//
// // Field is ignored by this package.
// Field bool `structs:"-"`
//
// It panics if s's kind is not struct.
func (s *Struct) Names() []string {
fields := getFields(s.value, s.TagName)
names := make([]string, len(fields))
for i, field := range fields {
names[i] = field.Name()
}
return names
}
func getFields(v reflect.Value, tagName string) []*Field {
if v.Kind() == reflect.Ptr {
v = v.Elem()
}
t := v.Type()
var fields []*Field
for i := 0; i < t.NumField(); i++ {
field := t.Field(i)
if tag := field.Tag.Get(tagName); tag == "-" {
continue
}
f := &Field{
field: field,
value: v.FieldByName(field.Name),
}
fields = append(fields, f)
}
return fields
}
// Field returns a new Field struct that provides several high level functions
// around a single struct field entity. It panics if the field is not found.
func (s *Struct) Field(name string) *Field {
f, ok := s.FieldOk(name)
if !ok {
panic("field not found")
}
return f
}
// FieldOk returns a new Field struct that provides several high level functions
// around a single struct field entity. The boolean returns true if the field
// was found.
func (s *Struct) FieldOk(name string) (*Field, bool) {
t := s.value.Type()
field, ok := t.FieldByName(name)
if !ok {
return nil, false
}
return &Field{
field: field,
value: s.value.FieldByName(name),
defaultTag: s.TagName,
}, true
}
// IsZero returns true if all fields in a struct is a zero value (not
// initialized) A struct tag with the content of "-" ignores the checking of
// that particular field. Example:
//
// // Field is ignored by this package.
// Field bool `structs:"-"`
//
// A value with the option of "omitnested" stops iterating further if the type
// is a struct. Example:
//
// // Field is not processed further by this package.
// Field time.Time `structs:"myName,omitnested"`
// Field *http.Request `structs:",omitnested"`
//
// Note that only exported fields of a struct can be accessed, non exported
// fields will be neglected. It panics if s's kind is not struct.
func (s *Struct) IsZero() bool {
fields := s.structFields()
for _, field := range fields {
val := s.value.FieldByName(field.Name)
_, tagOpts := parseTag(field.Tag.Get(s.TagName))
if IsStruct(val.Interface()) && !tagOpts.Has("omitnested") {
ok := IsZero(val.Interface())
if !ok {
return false
}
continue
}
// zero value of the given field, such as "" for string, 0 for int
zero := reflect.Zero(val.Type()).Interface()
// current value of the given field
current := val.Interface()
if !reflect.DeepEqual(current, zero) {
return false
}
}
return true
}
// HasZero returns true if a field in a struct is not initialized (zero value).
// A struct tag with the content of "-" ignores the checking of that particular
// field. Example:
//
// // Field is ignored by this package.
// Field bool `structs:"-"`
//
// A value with the option of "omitnested" stops iterating further if the type
// is a struct. Example:
//
// // Field is not processed further by this package.
// Field time.Time `structs:"myName,omitnested"`
// Field *http.Request `structs:",omitnested"`
//
// Note that only exported fields of a struct can be accessed, non exported
// fields will be neglected. It panics if s's kind is not struct.
func (s *Struct) HasZero() bool {
fields := s.structFields()
for _, field := range fields {
val := s.value.FieldByName(field.Name)
_, tagOpts := parseTag(field.Tag.Get(s.TagName))
if IsStruct(val.Interface()) && !tagOpts.Has("omitnested") {
ok := HasZero(val.Interface())
if ok {
return true
}
continue
}
// zero value of the given field, such as "" for string, 0 for int
zero := reflect.Zero(val.Type()).Interface()
// current value of the given field
current := val.Interface()
if reflect.DeepEqual(current, zero) {
return true
}
}
return false
}
// Name returns the structs's type name within its package. For more info refer
// to Name() function.
func (s *Struct) Name() string {
return s.value.Type().Name()
}
// structFields returns the exported struct fields for a given s struct. This
// is a convenient helper method to avoid duplicate code in some of the
// functions.
func (s *Struct) structFields() []reflect.StructField {
t := s.value.Type()
var f []reflect.StructField
for i := 0; i < t.NumField(); i++ {
field := t.Field(i)
// we can't access the value of unexported fields
if field.PkgPath != "" {
continue
}
// don't check if it's omitted
if tag := field.Tag.Get(s.TagName); tag == "-" {
continue
}
f = append(f, field)
}
return f
}
func strctVal(s interface{}) reflect.Value {
v := reflect.ValueOf(s)
// if pointer get the underlying element≤
for v.Kind() == reflect.Ptr {
v = v.Elem()
}
if v.Kind() != reflect.Struct {
panic("not struct")
}
return v
}
// Map converts the given struct to a map[string]interface{}. For more info
// refer to Struct types Map() method. It panics if s's kind is not struct.
func Map(s interface{}) map[string]interface{} {
return New(s).Map()
}
// FillMap is the same as Map. Instead of returning the output, it fills the
// given map.
func FillMap(s interface{}, out map[string]interface{}) {
New(s).FillMap(out)
}
// Values converts the given struct to a []interface{}. For more info refer to
// Struct types Values() method. It panics if s's kind is not struct.
func Values(s interface{}) []interface{} {
return New(s).Values()
}
// Fields returns a slice of *Field. For more info refer to Struct types
// Fields() method. It panics if s's kind is not struct.
func Fields(s interface{}) []*Field {
return New(s).Fields()
}
// Names returns a slice of field names. For more info refer to Struct types
// Names() method. It panics if s's kind is not struct.
func Names(s interface{}) []string {
return New(s).Names()
}
// IsZero returns true if all fields is equal to a zero value. For more info
// refer to Struct types IsZero() method. It panics if s's kind is not struct.
func IsZero(s interface{}) bool {
return New(s).IsZero()
}
// HasZero returns true if any field is equal to a zero value. For more info
// refer to Struct types HasZero() method. It panics if s's kind is not struct.
func HasZero(s interface{}) bool {
return New(s).HasZero()
}
// IsStruct returns true if the given variable is a struct or a pointer to
// struct.
func IsStruct(s interface{}) bool {
v := reflect.ValueOf(s)
if v.Kind() == reflect.Ptr {
v = v.Elem()
}
// uninitialized zero value of a struct
if v.Kind() == reflect.Invalid {
return false
}
return v.Kind() == reflect.Struct
}
// Name returns the structs's type name within its package. It returns an
// empty string for unnamed types. It panics if s's kind is not struct.
func Name(s interface{}) string {
return New(s).Name()
}
// nested retrieves recursively all types for the given value and returns the
// nested value.
func (s *Struct) nested(val reflect.Value) interface{} {
var finalVal interface{}
v := reflect.ValueOf(val.Interface())
if v.Kind() == reflect.Ptr {
v = v.Elem()
}
switch v.Kind() {
case reflect.Struct:
n := New(val.Interface())
n.TagName = s.TagName
m := n.Map()
// do not add the converted value if there are no exported fields, ie:
// time.Time
if len(m) == 0 {
finalVal = val.Interface()
} else {
finalVal = m
}
case reflect.Map:
// get the element type of the map
mapElem := val.Type()
switch val.Type().Kind() {
case reflect.Ptr, reflect.Array, reflect.Map,
reflect.Slice, reflect.Chan:
mapElem = val.Type().Elem()
if mapElem.Kind() == reflect.Ptr {
mapElem = mapElem.Elem()
}
}
// only iterate over struct types, ie: map[string]StructType,
// map[string][]StructType,
if mapElem.Kind() == reflect.Struct ||
(mapElem.Kind() == reflect.Slice &&
mapElem.Elem().Kind() == reflect.Struct) {
m := make(map[string]interface{}, val.Len())
for _, k := range val.MapKeys() {
m[k.String()] = s.nested(val.MapIndex(k))
}
finalVal = m
break
}
// TODO(arslan): should this be optional?
finalVal = val.Interface()
case reflect.Slice, reflect.Array:
if val.Type().Kind() == reflect.Interface {
finalVal = val.Interface()
break
}
// TODO(arslan): should this be optional?
// do not iterate of non struct types, just pass the value. Ie: []int,
// []string, co... We only iterate further if it's a struct.
// i.e []foo or []*foo
if val.Type().Elem().Kind() != reflect.Struct &&
!(val.Type().Elem().Kind() == reflect.Ptr &&
val.Type().Elem().Elem().Kind() == reflect.Struct) {
finalVal = val.Interface()
break
}
slices := make([]interface{}, val.Len())
for x := 0; x < val.Len(); x++ {
slices[x] = s.nested(val.Index(x))
}
finalVal = slices
default:
finalVal = val.Interface()
}
return finalVal
}