Mercurial > yakumo_izuru > aya
comparison vendor/gopkg.in/yaml.v3/yaml.go @ 74:d8727551f403 draft
The Empress (III)
* Change the way how versions are handled in version.go (to ease `go
install`)
* Upgrade yaml.v2 to yaml.v3
Signed-off-by: Izuru Yakumo <yakumo.izuru@chaotic.ninja>
author | yakumo.izuru |
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date | Mon, 04 Dec 2023 00:54:29 +0000 |
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73:8533d875a2bb | 74:d8727551f403 |
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1 // | |
2 // Copyright (c) 2011-2019 Canonical Ltd | |
3 // | |
4 // Licensed under the Apache License, Version 2.0 (the "License"); | |
5 // you may not use this file except in compliance with the License. | |
6 // You may obtain a copy of the License at | |
7 // | |
8 // http://www.apache.org/licenses/LICENSE-2.0 | |
9 // | |
10 // Unless required by applicable law or agreed to in writing, software | |
11 // distributed under the License is distributed on an "AS IS" BASIS, | |
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
13 // See the License for the specific language governing permissions and | |
14 // limitations under the License. | |
15 | |
16 // Package yaml implements YAML support for the Go language. | |
17 // | |
18 // Source code and other details for the project are available at GitHub: | |
19 // | |
20 // https://github.com/go-yaml/yaml | |
21 // | |
22 package yaml | |
23 | |
24 import ( | |
25 "errors" | |
26 "fmt" | |
27 "io" | |
28 "reflect" | |
29 "strings" | |
30 "sync" | |
31 "unicode/utf8" | |
32 ) | |
33 | |
34 // The Unmarshaler interface may be implemented by types to customize their | |
35 // behavior when being unmarshaled from a YAML document. | |
36 type Unmarshaler interface { | |
37 UnmarshalYAML(value *Node) error | |
38 } | |
39 | |
40 type obsoleteUnmarshaler interface { | |
41 UnmarshalYAML(unmarshal func(interface{}) error) error | |
42 } | |
43 | |
44 // The Marshaler interface may be implemented by types to customize their | |
45 // behavior when being marshaled into a YAML document. The returned value | |
46 // is marshaled in place of the original value implementing Marshaler. | |
47 // | |
48 // If an error is returned by MarshalYAML, the marshaling procedure stops | |
49 // and returns with the provided error. | |
50 type Marshaler interface { | |
51 MarshalYAML() (interface{}, error) | |
52 } | |
53 | |
54 // Unmarshal decodes the first document found within the in byte slice | |
55 // and assigns decoded values into the out value. | |
56 // | |
57 // Maps and pointers (to a struct, string, int, etc) are accepted as out | |
58 // values. If an internal pointer within a struct is not initialized, | |
59 // the yaml package will initialize it if necessary for unmarshalling | |
60 // the provided data. The out parameter must not be nil. | |
61 // | |
62 // The type of the decoded values should be compatible with the respective | |
63 // values in out. If one or more values cannot be decoded due to a type | |
64 // mismatches, decoding continues partially until the end of the YAML | |
65 // content, and a *yaml.TypeError is returned with details for all | |
66 // missed values. | |
67 // | |
68 // Struct fields are only unmarshalled if they are exported (have an | |
69 // upper case first letter), and are unmarshalled using the field name | |
70 // lowercased as the default key. Custom keys may be defined via the | |
71 // "yaml" name in the field tag: the content preceding the first comma | |
72 // is used as the key, and the following comma-separated options are | |
73 // used to tweak the marshalling process (see Marshal). | |
74 // Conflicting names result in a runtime error. | |
75 // | |
76 // For example: | |
77 // | |
78 // type T struct { | |
79 // F int `yaml:"a,omitempty"` | |
80 // B int | |
81 // } | |
82 // var t T | |
83 // yaml.Unmarshal([]byte("a: 1\nb: 2"), &t) | |
84 // | |
85 // See the documentation of Marshal for the format of tags and a list of | |
86 // supported tag options. | |
87 // | |
88 func Unmarshal(in []byte, out interface{}) (err error) { | |
89 return unmarshal(in, out, false) | |
90 } | |
91 | |
92 // A Decoder reads and decodes YAML values from an input stream. | |
93 type Decoder struct { | |
94 parser *parser | |
95 knownFields bool | |
96 } | |
97 | |
98 // NewDecoder returns a new decoder that reads from r. | |
99 // | |
100 // The decoder introduces its own buffering and may read | |
101 // data from r beyond the YAML values requested. | |
102 func NewDecoder(r io.Reader) *Decoder { | |
103 return &Decoder{ | |
104 parser: newParserFromReader(r), | |
105 } | |
106 } | |
107 | |
108 // KnownFields ensures that the keys in decoded mappings to | |
109 // exist as fields in the struct being decoded into. | |
110 func (dec *Decoder) KnownFields(enable bool) { | |
111 dec.knownFields = enable | |
112 } | |
113 | |
114 // Decode reads the next YAML-encoded value from its input | |
115 // and stores it in the value pointed to by v. | |
116 // | |
117 // See the documentation for Unmarshal for details about the | |
118 // conversion of YAML into a Go value. | |
119 func (dec *Decoder) Decode(v interface{}) (err error) { | |
120 d := newDecoder() | |
121 d.knownFields = dec.knownFields | |
122 defer handleErr(&err) | |
123 node := dec.parser.parse() | |
124 if node == nil { | |
125 return io.EOF | |
126 } | |
127 out := reflect.ValueOf(v) | |
128 if out.Kind() == reflect.Ptr && !out.IsNil() { | |
129 out = out.Elem() | |
130 } | |
131 d.unmarshal(node, out) | |
132 if len(d.terrors) > 0 { | |
133 return &TypeError{d.terrors} | |
134 } | |
135 return nil | |
136 } | |
137 | |
138 // Decode decodes the node and stores its data into the value pointed to by v. | |
139 // | |
140 // See the documentation for Unmarshal for details about the | |
141 // conversion of YAML into a Go value. | |
142 func (n *Node) Decode(v interface{}) (err error) { | |
143 d := newDecoder() | |
144 defer handleErr(&err) | |
145 out := reflect.ValueOf(v) | |
146 if out.Kind() == reflect.Ptr && !out.IsNil() { | |
147 out = out.Elem() | |
148 } | |
149 d.unmarshal(n, out) | |
150 if len(d.terrors) > 0 { | |
151 return &TypeError{d.terrors} | |
152 } | |
153 return nil | |
154 } | |
155 | |
156 func unmarshal(in []byte, out interface{}, strict bool) (err error) { | |
157 defer handleErr(&err) | |
158 d := newDecoder() | |
159 p := newParser(in) | |
160 defer p.destroy() | |
161 node := p.parse() | |
162 if node != nil { | |
163 v := reflect.ValueOf(out) | |
164 if v.Kind() == reflect.Ptr && !v.IsNil() { | |
165 v = v.Elem() | |
166 } | |
167 d.unmarshal(node, v) | |
168 } | |
169 if len(d.terrors) > 0 { | |
170 return &TypeError{d.terrors} | |
171 } | |
172 return nil | |
173 } | |
174 | |
175 // Marshal serializes the value provided into a YAML document. The structure | |
176 // of the generated document will reflect the structure of the value itself. | |
177 // Maps and pointers (to struct, string, int, etc) are accepted as the in value. | |
178 // | |
179 // Struct fields are only marshalled if they are exported (have an upper case | |
180 // first letter), and are marshalled using the field name lowercased as the | |
181 // default key. Custom keys may be defined via the "yaml" name in the field | |
182 // tag: the content preceding the first comma is used as the key, and the | |
183 // following comma-separated options are used to tweak the marshalling process. | |
184 // Conflicting names result in a runtime error. | |
185 // | |
186 // The field tag format accepted is: | |
187 // | |
188 // `(...) yaml:"[<key>][,<flag1>[,<flag2>]]" (...)` | |
189 // | |
190 // The following flags are currently supported: | |
191 // | |
192 // omitempty Only include the field if it's not set to the zero | |
193 // value for the type or to empty slices or maps. | |
194 // Zero valued structs will be omitted if all their public | |
195 // fields are zero, unless they implement an IsZero | |
196 // method (see the IsZeroer interface type), in which | |
197 // case the field will be excluded if IsZero returns true. | |
198 // | |
199 // flow Marshal using a flow style (useful for structs, | |
200 // sequences and maps). | |
201 // | |
202 // inline Inline the field, which must be a struct or a map, | |
203 // causing all of its fields or keys to be processed as if | |
204 // they were part of the outer struct. For maps, keys must | |
205 // not conflict with the yaml keys of other struct fields. | |
206 // | |
207 // In addition, if the key is "-", the field is ignored. | |
208 // | |
209 // For example: | |
210 // | |
211 // type T struct { | |
212 // F int `yaml:"a,omitempty"` | |
213 // B int | |
214 // } | |
215 // yaml.Marshal(&T{B: 2}) // Returns "b: 2\n" | |
216 // yaml.Marshal(&T{F: 1}} // Returns "a: 1\nb: 0\n" | |
217 // | |
218 func Marshal(in interface{}) (out []byte, err error) { | |
219 defer handleErr(&err) | |
220 e := newEncoder() | |
221 defer e.destroy() | |
222 e.marshalDoc("", reflect.ValueOf(in)) | |
223 e.finish() | |
224 out = e.out | |
225 return | |
226 } | |
227 | |
228 // An Encoder writes YAML values to an output stream. | |
229 type Encoder struct { | |
230 encoder *encoder | |
231 } | |
232 | |
233 // NewEncoder returns a new encoder that writes to w. | |
234 // The Encoder should be closed after use to flush all data | |
235 // to w. | |
236 func NewEncoder(w io.Writer) *Encoder { | |
237 return &Encoder{ | |
238 encoder: newEncoderWithWriter(w), | |
239 } | |
240 } | |
241 | |
242 // Encode writes the YAML encoding of v to the stream. | |
243 // If multiple items are encoded to the stream, the | |
244 // second and subsequent document will be preceded | |
245 // with a "---" document separator, but the first will not. | |
246 // | |
247 // See the documentation for Marshal for details about the conversion of Go | |
248 // values to YAML. | |
249 func (e *Encoder) Encode(v interface{}) (err error) { | |
250 defer handleErr(&err) | |
251 e.encoder.marshalDoc("", reflect.ValueOf(v)) | |
252 return nil | |
253 } | |
254 | |
255 // Encode encodes value v and stores its representation in n. | |
256 // | |
257 // See the documentation for Marshal for details about the | |
258 // conversion of Go values into YAML. | |
259 func (n *Node) Encode(v interface{}) (err error) { | |
260 defer handleErr(&err) | |
261 e := newEncoder() | |
262 defer e.destroy() | |
263 e.marshalDoc("", reflect.ValueOf(v)) | |
264 e.finish() | |
265 p := newParser(e.out) | |
266 p.textless = true | |
267 defer p.destroy() | |
268 doc := p.parse() | |
269 *n = *doc.Content[0] | |
270 return nil | |
271 } | |
272 | |
273 // SetIndent changes the used indentation used when encoding. | |
274 func (e *Encoder) SetIndent(spaces int) { | |
275 if spaces < 0 { | |
276 panic("yaml: cannot indent to a negative number of spaces") | |
277 } | |
278 e.encoder.indent = spaces | |
279 } | |
280 | |
281 // Close closes the encoder by writing any remaining data. | |
282 // It does not write a stream terminating string "...". | |
283 func (e *Encoder) Close() (err error) { | |
284 defer handleErr(&err) | |
285 e.encoder.finish() | |
286 return nil | |
287 } | |
288 | |
289 func handleErr(err *error) { | |
290 if v := recover(); v != nil { | |
291 if e, ok := v.(yamlError); ok { | |
292 *err = e.err | |
293 } else { | |
294 panic(v) | |
295 } | |
296 } | |
297 } | |
298 | |
299 type yamlError struct { | |
300 err error | |
301 } | |
302 | |
303 func fail(err error) { | |
304 panic(yamlError{err}) | |
305 } | |
306 | |
307 func failf(format string, args ...interface{}) { | |
308 panic(yamlError{fmt.Errorf("yaml: "+format, args...)}) | |
309 } | |
310 | |
311 // A TypeError is returned by Unmarshal when one or more fields in | |
312 // the YAML document cannot be properly decoded into the requested | |
313 // types. When this error is returned, the value is still | |
314 // unmarshaled partially. | |
315 type TypeError struct { | |
316 Errors []string | |
317 } | |
318 | |
319 func (e *TypeError) Error() string { | |
320 return fmt.Sprintf("yaml: unmarshal errors:\n %s", strings.Join(e.Errors, "\n ")) | |
321 } | |
322 | |
323 type Kind uint32 | |
324 | |
325 const ( | |
326 DocumentNode Kind = 1 << iota | |
327 SequenceNode | |
328 MappingNode | |
329 ScalarNode | |
330 AliasNode | |
331 ) | |
332 | |
333 type Style uint32 | |
334 | |
335 const ( | |
336 TaggedStyle Style = 1 << iota | |
337 DoubleQuotedStyle | |
338 SingleQuotedStyle | |
339 LiteralStyle | |
340 FoldedStyle | |
341 FlowStyle | |
342 ) | |
343 | |
344 // Node represents an element in the YAML document hierarchy. While documents | |
345 // are typically encoded and decoded into higher level types, such as structs | |
346 // and maps, Node is an intermediate representation that allows detailed | |
347 // control over the content being decoded or encoded. | |
348 // | |
349 // It's worth noting that although Node offers access into details such as | |
350 // line numbers, colums, and comments, the content when re-encoded will not | |
351 // have its original textual representation preserved. An effort is made to | |
352 // render the data plesantly, and to preserve comments near the data they | |
353 // describe, though. | |
354 // | |
355 // Values that make use of the Node type interact with the yaml package in the | |
356 // same way any other type would do, by encoding and decoding yaml data | |
357 // directly or indirectly into them. | |
358 // | |
359 // For example: | |
360 // | |
361 // var person struct { | |
362 // Name string | |
363 // Address yaml.Node | |
364 // } | |
365 // err := yaml.Unmarshal(data, &person) | |
366 // | |
367 // Or by itself: | |
368 // | |
369 // var person Node | |
370 // err := yaml.Unmarshal(data, &person) | |
371 // | |
372 type Node struct { | |
373 // Kind defines whether the node is a document, a mapping, a sequence, | |
374 // a scalar value, or an alias to another node. The specific data type of | |
375 // scalar nodes may be obtained via the ShortTag and LongTag methods. | |
376 Kind Kind | |
377 | |
378 // Style allows customizing the apperance of the node in the tree. | |
379 Style Style | |
380 | |
381 // Tag holds the YAML tag defining the data type for the value. | |
382 // When decoding, this field will always be set to the resolved tag, | |
383 // even when it wasn't explicitly provided in the YAML content. | |
384 // When encoding, if this field is unset the value type will be | |
385 // implied from the node properties, and if it is set, it will only | |
386 // be serialized into the representation if TaggedStyle is used or | |
387 // the implicit tag diverges from the provided one. | |
388 Tag string | |
389 | |
390 // Value holds the unescaped and unquoted represenation of the value. | |
391 Value string | |
392 | |
393 // Anchor holds the anchor name for this node, which allows aliases to point to it. | |
394 Anchor string | |
395 | |
396 // Alias holds the node that this alias points to. Only valid when Kind is AliasNode. | |
397 Alias *Node | |
398 | |
399 // Content holds contained nodes for documents, mappings, and sequences. | |
400 Content []*Node | |
401 | |
402 // HeadComment holds any comments in the lines preceding the node and | |
403 // not separated by an empty line. | |
404 HeadComment string | |
405 | |
406 // LineComment holds any comments at the end of the line where the node is in. | |
407 LineComment string | |
408 | |
409 // FootComment holds any comments following the node and before empty lines. | |
410 FootComment string | |
411 | |
412 // Line and Column hold the node position in the decoded YAML text. | |
413 // These fields are not respected when encoding the node. | |
414 Line int | |
415 Column int | |
416 } | |
417 | |
418 // IsZero returns whether the node has all of its fields unset. | |
419 func (n *Node) IsZero() bool { | |
420 return n.Kind == 0 && n.Style == 0 && n.Tag == "" && n.Value == "" && n.Anchor == "" && n.Alias == nil && n.Content == nil && | |
421 n.HeadComment == "" && n.LineComment == "" && n.FootComment == "" && n.Line == 0 && n.Column == 0 | |
422 } | |
423 | |
424 | |
425 // LongTag returns the long form of the tag that indicates the data type for | |
426 // the node. If the Tag field isn't explicitly defined, one will be computed | |
427 // based on the node properties. | |
428 func (n *Node) LongTag() string { | |
429 return longTag(n.ShortTag()) | |
430 } | |
431 | |
432 // ShortTag returns the short form of the YAML tag that indicates data type for | |
433 // the node. If the Tag field isn't explicitly defined, one will be computed | |
434 // based on the node properties. | |
435 func (n *Node) ShortTag() string { | |
436 if n.indicatedString() { | |
437 return strTag | |
438 } | |
439 if n.Tag == "" || n.Tag == "!" { | |
440 switch n.Kind { | |
441 case MappingNode: | |
442 return mapTag | |
443 case SequenceNode: | |
444 return seqTag | |
445 case AliasNode: | |
446 if n.Alias != nil { | |
447 return n.Alias.ShortTag() | |
448 } | |
449 case ScalarNode: | |
450 tag, _ := resolve("", n.Value) | |
451 return tag | |
452 case 0: | |
453 // Special case to make the zero value convenient. | |
454 if n.IsZero() { | |
455 return nullTag | |
456 } | |
457 } | |
458 return "" | |
459 } | |
460 return shortTag(n.Tag) | |
461 } | |
462 | |
463 func (n *Node) indicatedString() bool { | |
464 return n.Kind == ScalarNode && | |
465 (shortTag(n.Tag) == strTag || | |
466 (n.Tag == "" || n.Tag == "!") && n.Style&(SingleQuotedStyle|DoubleQuotedStyle|LiteralStyle|FoldedStyle) != 0) | |
467 } | |
468 | |
469 // SetString is a convenience function that sets the node to a string value | |
470 // and defines its style in a pleasant way depending on its content. | |
471 func (n *Node) SetString(s string) { | |
472 n.Kind = ScalarNode | |
473 if utf8.ValidString(s) { | |
474 n.Value = s | |
475 n.Tag = strTag | |
476 } else { | |
477 n.Value = encodeBase64(s) | |
478 n.Tag = binaryTag | |
479 } | |
480 if strings.Contains(n.Value, "\n") { | |
481 n.Style = LiteralStyle | |
482 } | |
483 } | |
484 | |
485 // -------------------------------------------------------------------------- | |
486 // Maintain a mapping of keys to structure field indexes | |
487 | |
488 // The code in this section was copied from mgo/bson. | |
489 | |
490 // structInfo holds details for the serialization of fields of | |
491 // a given struct. | |
492 type structInfo struct { | |
493 FieldsMap map[string]fieldInfo | |
494 FieldsList []fieldInfo | |
495 | |
496 // InlineMap is the number of the field in the struct that | |
497 // contains an ,inline map, or -1 if there's none. | |
498 InlineMap int | |
499 | |
500 // InlineUnmarshalers holds indexes to inlined fields that | |
501 // contain unmarshaler values. | |
502 InlineUnmarshalers [][]int | |
503 } | |
504 | |
505 type fieldInfo struct { | |
506 Key string | |
507 Num int | |
508 OmitEmpty bool | |
509 Flow bool | |
510 // Id holds the unique field identifier, so we can cheaply | |
511 // check for field duplicates without maintaining an extra map. | |
512 Id int | |
513 | |
514 // Inline holds the field index if the field is part of an inlined struct. | |
515 Inline []int | |
516 } | |
517 | |
518 var structMap = make(map[reflect.Type]*structInfo) | |
519 var fieldMapMutex sync.RWMutex | |
520 var unmarshalerType reflect.Type | |
521 | |
522 func init() { | |
523 var v Unmarshaler | |
524 unmarshalerType = reflect.ValueOf(&v).Elem().Type() | |
525 } | |
526 | |
527 func getStructInfo(st reflect.Type) (*structInfo, error) { | |
528 fieldMapMutex.RLock() | |
529 sinfo, found := structMap[st] | |
530 fieldMapMutex.RUnlock() | |
531 if found { | |
532 return sinfo, nil | |
533 } | |
534 | |
535 n := st.NumField() | |
536 fieldsMap := make(map[string]fieldInfo) | |
537 fieldsList := make([]fieldInfo, 0, n) | |
538 inlineMap := -1 | |
539 inlineUnmarshalers := [][]int(nil) | |
540 for i := 0; i != n; i++ { | |
541 field := st.Field(i) | |
542 if field.PkgPath != "" && !field.Anonymous { | |
543 continue // Private field | |
544 } | |
545 | |
546 info := fieldInfo{Num: i} | |
547 | |
548 tag := field.Tag.Get("yaml") | |
549 if tag == "" && strings.Index(string(field.Tag), ":") < 0 { | |
550 tag = string(field.Tag) | |
551 } | |
552 if tag == "-" { | |
553 continue | |
554 } | |
555 | |
556 inline := false | |
557 fields := strings.Split(tag, ",") | |
558 if len(fields) > 1 { | |
559 for _, flag := range fields[1:] { | |
560 switch flag { | |
561 case "omitempty": | |
562 info.OmitEmpty = true | |
563 case "flow": | |
564 info.Flow = true | |
565 case "inline": | |
566 inline = true | |
567 default: | |
568 return nil, errors.New(fmt.Sprintf("unsupported flag %q in tag %q of type %s", flag, tag, st)) | |
569 } | |
570 } | |
571 tag = fields[0] | |
572 } | |
573 | |
574 if inline { | |
575 switch field.Type.Kind() { | |
576 case reflect.Map: | |
577 if inlineMap >= 0 { | |
578 return nil, errors.New("multiple ,inline maps in struct " + st.String()) | |
579 } | |
580 if field.Type.Key() != reflect.TypeOf("") { | |
581 return nil, errors.New("option ,inline needs a map with string keys in struct " + st.String()) | |
582 } | |
583 inlineMap = info.Num | |
584 case reflect.Struct, reflect.Ptr: | |
585 ftype := field.Type | |
586 for ftype.Kind() == reflect.Ptr { | |
587 ftype = ftype.Elem() | |
588 } | |
589 if ftype.Kind() != reflect.Struct { | |
590 return nil, errors.New("option ,inline may only be used on a struct or map field") | |
591 } | |
592 if reflect.PtrTo(ftype).Implements(unmarshalerType) { | |
593 inlineUnmarshalers = append(inlineUnmarshalers, []int{i}) | |
594 } else { | |
595 sinfo, err := getStructInfo(ftype) | |
596 if err != nil { | |
597 return nil, err | |
598 } | |
599 for _, index := range sinfo.InlineUnmarshalers { | |
600 inlineUnmarshalers = append(inlineUnmarshalers, append([]int{i}, index...)) | |
601 } | |
602 for _, finfo := range sinfo.FieldsList { | |
603 if _, found := fieldsMap[finfo.Key]; found { | |
604 msg := "duplicated key '" + finfo.Key + "' in struct " + st.String() | |
605 return nil, errors.New(msg) | |
606 } | |
607 if finfo.Inline == nil { | |
608 finfo.Inline = []int{i, finfo.Num} | |
609 } else { | |
610 finfo.Inline = append([]int{i}, finfo.Inline...) | |
611 } | |
612 finfo.Id = len(fieldsList) | |
613 fieldsMap[finfo.Key] = finfo | |
614 fieldsList = append(fieldsList, finfo) | |
615 } | |
616 } | |
617 default: | |
618 return nil, errors.New("option ,inline may only be used on a struct or map field") | |
619 } | |
620 continue | |
621 } | |
622 | |
623 if tag != "" { | |
624 info.Key = tag | |
625 } else { | |
626 info.Key = strings.ToLower(field.Name) | |
627 } | |
628 | |
629 if _, found = fieldsMap[info.Key]; found { | |
630 msg := "duplicated key '" + info.Key + "' in struct " + st.String() | |
631 return nil, errors.New(msg) | |
632 } | |
633 | |
634 info.Id = len(fieldsList) | |
635 fieldsList = append(fieldsList, info) | |
636 fieldsMap[info.Key] = info | |
637 } | |
638 | |
639 sinfo = &structInfo{ | |
640 FieldsMap: fieldsMap, | |
641 FieldsList: fieldsList, | |
642 InlineMap: inlineMap, | |
643 InlineUnmarshalers: inlineUnmarshalers, | |
644 } | |
645 | |
646 fieldMapMutex.Lock() | |
647 structMap[st] = sinfo | |
648 fieldMapMutex.Unlock() | |
649 return sinfo, nil | |
650 } | |
651 | |
652 // IsZeroer is used to check whether an object is zero to | |
653 // determine whether it should be omitted when marshaling | |
654 // with the omitempty flag. One notable implementation | |
655 // is time.Time. | |
656 type IsZeroer interface { | |
657 IsZero() bool | |
658 } | |
659 | |
660 func isZero(v reflect.Value) bool { | |
661 kind := v.Kind() | |
662 if z, ok := v.Interface().(IsZeroer); ok { | |
663 if (kind == reflect.Ptr || kind == reflect.Interface) && v.IsNil() { | |
664 return true | |
665 } | |
666 return z.IsZero() | |
667 } | |
668 switch kind { | |
669 case reflect.String: | |
670 return len(v.String()) == 0 | |
671 case reflect.Interface, reflect.Ptr: | |
672 return v.IsNil() | |
673 case reflect.Slice: | |
674 return v.Len() == 0 | |
675 case reflect.Map: | |
676 return v.Len() == 0 | |
677 case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: | |
678 return v.Int() == 0 | |
679 case reflect.Float32, reflect.Float64: | |
680 return v.Float() == 0 | |
681 case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: | |
682 return v.Uint() == 0 | |
683 case reflect.Bool: | |
684 return !v.Bool() | |
685 case reflect.Struct: | |
686 vt := v.Type() | |
687 for i := v.NumField() - 1; i >= 0; i-- { | |
688 if vt.Field(i).PkgPath != "" { | |
689 continue // Private field | |
690 } | |
691 if !isZero(v.Field(i)) { | |
692 return false | |
693 } | |
694 } | |
695 return true | |
696 } | |
697 return false | |
698 } |