David K. Bainbridge | bd6b288 | 2021-08-26 13:31:02 +0000 | [diff] [blame] | 1 | // Copyright 2018 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package impl |
| 6 | |
| 7 | import ( |
| 8 | "fmt" |
| 9 | "math" |
| 10 | "reflect" |
| 11 | "sync" |
| 12 | |
| 13 | "google.golang.org/protobuf/internal/flags" |
| 14 | pref "google.golang.org/protobuf/reflect/protoreflect" |
| 15 | preg "google.golang.org/protobuf/reflect/protoregistry" |
| 16 | ) |
| 17 | |
| 18 | type fieldInfo struct { |
| 19 | fieldDesc pref.FieldDescriptor |
| 20 | |
| 21 | // These fields are used for protobuf reflection support. |
| 22 | has func(pointer) bool |
| 23 | clear func(pointer) |
| 24 | get func(pointer) pref.Value |
| 25 | set func(pointer, pref.Value) |
| 26 | mutable func(pointer) pref.Value |
| 27 | newMessage func() pref.Message |
| 28 | newField func() pref.Value |
| 29 | } |
| 30 | |
| 31 | func fieldInfoForMissing(fd pref.FieldDescriptor) fieldInfo { |
| 32 | // This never occurs for generated message types. |
| 33 | // It implies that a hand-crafted type has missing Go fields |
| 34 | // for specific protobuf message fields. |
| 35 | return fieldInfo{ |
| 36 | fieldDesc: fd, |
| 37 | has: func(p pointer) bool { |
| 38 | return false |
| 39 | }, |
| 40 | clear: func(p pointer) { |
| 41 | panic("missing Go struct field for " + string(fd.FullName())) |
| 42 | }, |
| 43 | get: func(p pointer) pref.Value { |
| 44 | return fd.Default() |
| 45 | }, |
| 46 | set: func(p pointer, v pref.Value) { |
| 47 | panic("missing Go struct field for " + string(fd.FullName())) |
| 48 | }, |
| 49 | mutable: func(p pointer) pref.Value { |
| 50 | panic("missing Go struct field for " + string(fd.FullName())) |
| 51 | }, |
| 52 | newMessage: func() pref.Message { |
| 53 | panic("missing Go struct field for " + string(fd.FullName())) |
| 54 | }, |
| 55 | newField: func() pref.Value { |
| 56 | if v := fd.Default(); v.IsValid() { |
| 57 | return v |
| 58 | } |
| 59 | panic("missing Go struct field for " + string(fd.FullName())) |
| 60 | }, |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | func fieldInfoForOneof(fd pref.FieldDescriptor, fs reflect.StructField, x exporter, ot reflect.Type) fieldInfo { |
| 65 | ft := fs.Type |
| 66 | if ft.Kind() != reflect.Interface { |
| 67 | panic(fmt.Sprintf("field %v has invalid type: got %v, want interface kind", fd.FullName(), ft)) |
| 68 | } |
| 69 | if ot.Kind() != reflect.Struct { |
| 70 | panic(fmt.Sprintf("field %v has invalid type: got %v, want struct kind", fd.FullName(), ot)) |
| 71 | } |
| 72 | if !reflect.PtrTo(ot).Implements(ft) { |
| 73 | panic(fmt.Sprintf("field %v has invalid type: %v does not implement %v", fd.FullName(), ot, ft)) |
| 74 | } |
| 75 | conv := NewConverter(ot.Field(0).Type, fd) |
| 76 | isMessage := fd.Message() != nil |
| 77 | |
| 78 | // TODO: Implement unsafe fast path? |
| 79 | fieldOffset := offsetOf(fs, x) |
| 80 | return fieldInfo{ |
| 81 | // NOTE: The logic below intentionally assumes that oneof fields are |
| 82 | // well-formatted. That is, the oneof interface never contains a |
| 83 | // typed nil pointer to one of the wrapper structs. |
| 84 | |
| 85 | fieldDesc: fd, |
| 86 | has: func(p pointer) bool { |
| 87 | if p.IsNil() { |
| 88 | return false |
| 89 | } |
| 90 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 91 | if rv.IsNil() || rv.Elem().Type().Elem() != ot || rv.Elem().IsNil() { |
| 92 | return false |
| 93 | } |
| 94 | return true |
| 95 | }, |
| 96 | clear: func(p pointer) { |
| 97 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 98 | if rv.IsNil() || rv.Elem().Type().Elem() != ot { |
| 99 | // NOTE: We intentionally don't check for rv.Elem().IsNil() |
| 100 | // so that (*OneofWrapperType)(nil) gets cleared to nil. |
| 101 | return |
| 102 | } |
| 103 | rv.Set(reflect.Zero(rv.Type())) |
| 104 | }, |
| 105 | get: func(p pointer) pref.Value { |
| 106 | if p.IsNil() { |
| 107 | return conv.Zero() |
| 108 | } |
| 109 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 110 | if rv.IsNil() || rv.Elem().Type().Elem() != ot || rv.Elem().IsNil() { |
| 111 | return conv.Zero() |
| 112 | } |
| 113 | rv = rv.Elem().Elem().Field(0) |
| 114 | return conv.PBValueOf(rv) |
| 115 | }, |
| 116 | set: func(p pointer, v pref.Value) { |
| 117 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 118 | if rv.IsNil() || rv.Elem().Type().Elem() != ot || rv.Elem().IsNil() { |
| 119 | rv.Set(reflect.New(ot)) |
| 120 | } |
| 121 | rv = rv.Elem().Elem().Field(0) |
| 122 | rv.Set(conv.GoValueOf(v)) |
| 123 | }, |
| 124 | mutable: func(p pointer) pref.Value { |
| 125 | if !isMessage { |
| 126 | panic(fmt.Sprintf("field %v with invalid Mutable call on field with non-composite type", fd.FullName())) |
| 127 | } |
| 128 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 129 | if rv.IsNil() || rv.Elem().Type().Elem() != ot || rv.Elem().IsNil() { |
| 130 | rv.Set(reflect.New(ot)) |
| 131 | } |
| 132 | rv = rv.Elem().Elem().Field(0) |
| 133 | if rv.Kind() == reflect.Ptr && rv.IsNil() { |
| 134 | rv.Set(conv.GoValueOf(pref.ValueOfMessage(conv.New().Message()))) |
| 135 | } |
| 136 | return conv.PBValueOf(rv) |
| 137 | }, |
| 138 | newMessage: func() pref.Message { |
| 139 | return conv.New().Message() |
| 140 | }, |
| 141 | newField: func() pref.Value { |
| 142 | return conv.New() |
| 143 | }, |
| 144 | } |
| 145 | } |
| 146 | |
| 147 | func fieldInfoForMap(fd pref.FieldDescriptor, fs reflect.StructField, x exporter) fieldInfo { |
| 148 | ft := fs.Type |
| 149 | if ft.Kind() != reflect.Map { |
| 150 | panic(fmt.Sprintf("field %v has invalid type: got %v, want map kind", fd.FullName(), ft)) |
| 151 | } |
| 152 | conv := NewConverter(ft, fd) |
| 153 | |
| 154 | // TODO: Implement unsafe fast path? |
| 155 | fieldOffset := offsetOf(fs, x) |
| 156 | return fieldInfo{ |
| 157 | fieldDesc: fd, |
| 158 | has: func(p pointer) bool { |
| 159 | if p.IsNil() { |
| 160 | return false |
| 161 | } |
| 162 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 163 | return rv.Len() > 0 |
| 164 | }, |
| 165 | clear: func(p pointer) { |
| 166 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 167 | rv.Set(reflect.Zero(rv.Type())) |
| 168 | }, |
| 169 | get: func(p pointer) pref.Value { |
| 170 | if p.IsNil() { |
| 171 | return conv.Zero() |
| 172 | } |
| 173 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 174 | if rv.Len() == 0 { |
| 175 | return conv.Zero() |
| 176 | } |
| 177 | return conv.PBValueOf(rv) |
| 178 | }, |
| 179 | set: func(p pointer, v pref.Value) { |
| 180 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 181 | pv := conv.GoValueOf(v) |
| 182 | if pv.IsNil() { |
| 183 | panic(fmt.Sprintf("map field %v cannot be set with read-only value", fd.FullName())) |
| 184 | } |
| 185 | rv.Set(pv) |
| 186 | }, |
| 187 | mutable: func(p pointer) pref.Value { |
| 188 | v := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 189 | if v.IsNil() { |
| 190 | v.Set(reflect.MakeMap(fs.Type)) |
| 191 | } |
| 192 | return conv.PBValueOf(v) |
| 193 | }, |
| 194 | newField: func() pref.Value { |
| 195 | return conv.New() |
| 196 | }, |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | func fieldInfoForList(fd pref.FieldDescriptor, fs reflect.StructField, x exporter) fieldInfo { |
| 201 | ft := fs.Type |
| 202 | if ft.Kind() != reflect.Slice { |
| 203 | panic(fmt.Sprintf("field %v has invalid type: got %v, want slice kind", fd.FullName(), ft)) |
| 204 | } |
| 205 | conv := NewConverter(reflect.PtrTo(ft), fd) |
| 206 | |
| 207 | // TODO: Implement unsafe fast path? |
| 208 | fieldOffset := offsetOf(fs, x) |
| 209 | return fieldInfo{ |
| 210 | fieldDesc: fd, |
| 211 | has: func(p pointer) bool { |
| 212 | if p.IsNil() { |
| 213 | return false |
| 214 | } |
| 215 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 216 | return rv.Len() > 0 |
| 217 | }, |
| 218 | clear: func(p pointer) { |
| 219 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 220 | rv.Set(reflect.Zero(rv.Type())) |
| 221 | }, |
| 222 | get: func(p pointer) pref.Value { |
| 223 | if p.IsNil() { |
| 224 | return conv.Zero() |
| 225 | } |
| 226 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type) |
| 227 | if rv.Elem().Len() == 0 { |
| 228 | return conv.Zero() |
| 229 | } |
| 230 | return conv.PBValueOf(rv) |
| 231 | }, |
| 232 | set: func(p pointer, v pref.Value) { |
| 233 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 234 | pv := conv.GoValueOf(v) |
| 235 | if pv.IsNil() { |
| 236 | panic(fmt.Sprintf("list field %v cannot be set with read-only value", fd.FullName())) |
| 237 | } |
| 238 | rv.Set(pv.Elem()) |
| 239 | }, |
| 240 | mutable: func(p pointer) pref.Value { |
| 241 | v := p.Apply(fieldOffset).AsValueOf(fs.Type) |
| 242 | return conv.PBValueOf(v) |
| 243 | }, |
| 244 | newField: func() pref.Value { |
| 245 | return conv.New() |
| 246 | }, |
| 247 | } |
| 248 | } |
| 249 | |
| 250 | var ( |
| 251 | nilBytes = reflect.ValueOf([]byte(nil)) |
| 252 | emptyBytes = reflect.ValueOf([]byte{}) |
| 253 | ) |
| 254 | |
| 255 | func fieldInfoForScalar(fd pref.FieldDescriptor, fs reflect.StructField, x exporter) fieldInfo { |
| 256 | ft := fs.Type |
| 257 | nullable := fd.HasPresence() |
| 258 | isBytes := ft.Kind() == reflect.Slice && ft.Elem().Kind() == reflect.Uint8 |
| 259 | if nullable { |
| 260 | if ft.Kind() != reflect.Ptr && ft.Kind() != reflect.Slice { |
| 261 | // This never occurs for generated message types. |
| 262 | // Despite the protobuf type system specifying presence, |
| 263 | // the Go field type cannot represent it. |
| 264 | nullable = false |
| 265 | } |
| 266 | if ft.Kind() == reflect.Ptr { |
| 267 | ft = ft.Elem() |
| 268 | } |
| 269 | } |
| 270 | conv := NewConverter(ft, fd) |
| 271 | |
| 272 | // TODO: Implement unsafe fast path? |
| 273 | fieldOffset := offsetOf(fs, x) |
| 274 | return fieldInfo{ |
| 275 | fieldDesc: fd, |
| 276 | has: func(p pointer) bool { |
| 277 | if p.IsNil() { |
| 278 | return false |
| 279 | } |
| 280 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 281 | if nullable { |
| 282 | return !rv.IsNil() |
| 283 | } |
| 284 | switch rv.Kind() { |
| 285 | case reflect.Bool: |
| 286 | return rv.Bool() |
| 287 | case reflect.Int32, reflect.Int64: |
| 288 | return rv.Int() != 0 |
| 289 | case reflect.Uint32, reflect.Uint64: |
| 290 | return rv.Uint() != 0 |
| 291 | case reflect.Float32, reflect.Float64: |
| 292 | return rv.Float() != 0 || math.Signbit(rv.Float()) |
| 293 | case reflect.String, reflect.Slice: |
| 294 | return rv.Len() > 0 |
| 295 | default: |
| 296 | panic(fmt.Sprintf("field %v has invalid type: %v", fd.FullName(), rv.Type())) // should never happen |
| 297 | } |
| 298 | }, |
| 299 | clear: func(p pointer) { |
| 300 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 301 | rv.Set(reflect.Zero(rv.Type())) |
| 302 | }, |
| 303 | get: func(p pointer) pref.Value { |
| 304 | if p.IsNil() { |
| 305 | return conv.Zero() |
| 306 | } |
| 307 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 308 | if nullable { |
| 309 | if rv.IsNil() { |
| 310 | return conv.Zero() |
| 311 | } |
| 312 | if rv.Kind() == reflect.Ptr { |
| 313 | rv = rv.Elem() |
| 314 | } |
| 315 | } |
| 316 | return conv.PBValueOf(rv) |
| 317 | }, |
| 318 | set: func(p pointer, v pref.Value) { |
| 319 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 320 | if nullable && rv.Kind() == reflect.Ptr { |
| 321 | if rv.IsNil() { |
| 322 | rv.Set(reflect.New(ft)) |
| 323 | } |
| 324 | rv = rv.Elem() |
| 325 | } |
| 326 | rv.Set(conv.GoValueOf(v)) |
| 327 | if isBytes && rv.Len() == 0 { |
| 328 | if nullable { |
| 329 | rv.Set(emptyBytes) // preserve presence |
| 330 | } else { |
| 331 | rv.Set(nilBytes) // do not preserve presence |
| 332 | } |
| 333 | } |
| 334 | }, |
| 335 | newField: func() pref.Value { |
| 336 | return conv.New() |
| 337 | }, |
| 338 | } |
| 339 | } |
| 340 | |
| 341 | func fieldInfoForWeakMessage(fd pref.FieldDescriptor, weakOffset offset) fieldInfo { |
| 342 | if !flags.ProtoLegacy { |
| 343 | panic("no support for proto1 weak fields") |
| 344 | } |
| 345 | |
| 346 | var once sync.Once |
| 347 | var messageType pref.MessageType |
| 348 | lazyInit := func() { |
| 349 | once.Do(func() { |
| 350 | messageName := fd.Message().FullName() |
| 351 | messageType, _ = preg.GlobalTypes.FindMessageByName(messageName) |
| 352 | if messageType == nil { |
| 353 | panic(fmt.Sprintf("weak message %v for field %v is not linked in", messageName, fd.FullName())) |
| 354 | } |
| 355 | }) |
| 356 | } |
| 357 | |
| 358 | num := fd.Number() |
| 359 | return fieldInfo{ |
| 360 | fieldDesc: fd, |
| 361 | has: func(p pointer) bool { |
| 362 | if p.IsNil() { |
| 363 | return false |
| 364 | } |
| 365 | _, ok := p.Apply(weakOffset).WeakFields().get(num) |
| 366 | return ok |
| 367 | }, |
| 368 | clear: func(p pointer) { |
| 369 | p.Apply(weakOffset).WeakFields().clear(num) |
| 370 | }, |
| 371 | get: func(p pointer) pref.Value { |
| 372 | lazyInit() |
| 373 | if p.IsNil() { |
| 374 | return pref.ValueOfMessage(messageType.Zero()) |
| 375 | } |
| 376 | m, ok := p.Apply(weakOffset).WeakFields().get(num) |
| 377 | if !ok { |
| 378 | return pref.ValueOfMessage(messageType.Zero()) |
| 379 | } |
| 380 | return pref.ValueOfMessage(m.ProtoReflect()) |
| 381 | }, |
| 382 | set: func(p pointer, v pref.Value) { |
| 383 | lazyInit() |
| 384 | m := v.Message() |
| 385 | if m.Descriptor() != messageType.Descriptor() { |
| 386 | if got, want := m.Descriptor().FullName(), messageType.Descriptor().FullName(); got != want { |
| 387 | panic(fmt.Sprintf("field %v has mismatching message descriptor: got %v, want %v", fd.FullName(), got, want)) |
| 388 | } |
| 389 | panic(fmt.Sprintf("field %v has mismatching message descriptor: %v", fd.FullName(), m.Descriptor().FullName())) |
| 390 | } |
| 391 | p.Apply(weakOffset).WeakFields().set(num, m.Interface()) |
| 392 | }, |
| 393 | mutable: func(p pointer) pref.Value { |
| 394 | lazyInit() |
| 395 | fs := p.Apply(weakOffset).WeakFields() |
| 396 | m, ok := fs.get(num) |
| 397 | if !ok { |
| 398 | m = messageType.New().Interface() |
| 399 | fs.set(num, m) |
| 400 | } |
| 401 | return pref.ValueOfMessage(m.ProtoReflect()) |
| 402 | }, |
| 403 | newMessage: func() pref.Message { |
| 404 | lazyInit() |
| 405 | return messageType.New() |
| 406 | }, |
| 407 | newField: func() pref.Value { |
| 408 | lazyInit() |
| 409 | return pref.ValueOfMessage(messageType.New()) |
| 410 | }, |
| 411 | } |
| 412 | } |
| 413 | |
| 414 | func fieldInfoForMessage(fd pref.FieldDescriptor, fs reflect.StructField, x exporter) fieldInfo { |
| 415 | ft := fs.Type |
| 416 | conv := NewConverter(ft, fd) |
| 417 | |
| 418 | // TODO: Implement unsafe fast path? |
| 419 | fieldOffset := offsetOf(fs, x) |
| 420 | return fieldInfo{ |
| 421 | fieldDesc: fd, |
| 422 | has: func(p pointer) bool { |
| 423 | if p.IsNil() { |
| 424 | return false |
| 425 | } |
| 426 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 427 | if fs.Type.Kind() != reflect.Ptr { |
| 428 | return !isZero(rv) |
| 429 | } |
| 430 | return !rv.IsNil() |
| 431 | }, |
| 432 | clear: func(p pointer) { |
| 433 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 434 | rv.Set(reflect.Zero(rv.Type())) |
| 435 | }, |
| 436 | get: func(p pointer) pref.Value { |
| 437 | if p.IsNil() { |
| 438 | return conv.Zero() |
| 439 | } |
| 440 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 441 | return conv.PBValueOf(rv) |
| 442 | }, |
| 443 | set: func(p pointer, v pref.Value) { |
| 444 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 445 | rv.Set(conv.GoValueOf(v)) |
| 446 | if fs.Type.Kind() == reflect.Ptr && rv.IsNil() { |
| 447 | panic(fmt.Sprintf("field %v has invalid nil pointer", fd.FullName())) |
| 448 | } |
| 449 | }, |
| 450 | mutable: func(p pointer) pref.Value { |
| 451 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 452 | if fs.Type.Kind() == reflect.Ptr && rv.IsNil() { |
| 453 | rv.Set(conv.GoValueOf(conv.New())) |
| 454 | } |
| 455 | return conv.PBValueOf(rv) |
| 456 | }, |
| 457 | newMessage: func() pref.Message { |
| 458 | return conv.New().Message() |
| 459 | }, |
| 460 | newField: func() pref.Value { |
| 461 | return conv.New() |
| 462 | }, |
| 463 | } |
| 464 | } |
| 465 | |
| 466 | type oneofInfo struct { |
| 467 | oneofDesc pref.OneofDescriptor |
| 468 | which func(pointer) pref.FieldNumber |
| 469 | } |
| 470 | |
| 471 | func makeOneofInfo(od pref.OneofDescriptor, si structInfo, x exporter) *oneofInfo { |
| 472 | oi := &oneofInfo{oneofDesc: od} |
| 473 | if od.IsSynthetic() { |
| 474 | fs := si.fieldsByNumber[od.Fields().Get(0).Number()] |
| 475 | fieldOffset := offsetOf(fs, x) |
| 476 | oi.which = func(p pointer) pref.FieldNumber { |
| 477 | if p.IsNil() { |
| 478 | return 0 |
| 479 | } |
| 480 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 481 | if rv.IsNil() { // valid on either *T or []byte |
| 482 | return 0 |
| 483 | } |
| 484 | return od.Fields().Get(0).Number() |
| 485 | } |
| 486 | } else { |
| 487 | fs := si.oneofsByName[od.Name()] |
| 488 | fieldOffset := offsetOf(fs, x) |
| 489 | oi.which = func(p pointer) pref.FieldNumber { |
| 490 | if p.IsNil() { |
| 491 | return 0 |
| 492 | } |
| 493 | rv := p.Apply(fieldOffset).AsValueOf(fs.Type).Elem() |
| 494 | if rv.IsNil() { |
| 495 | return 0 |
| 496 | } |
| 497 | rv = rv.Elem() |
| 498 | if rv.IsNil() { |
| 499 | return 0 |
| 500 | } |
| 501 | return si.oneofWrappersByType[rv.Type().Elem()] |
| 502 | } |
| 503 | } |
| 504 | return oi |
| 505 | } |
| 506 | |
| 507 | // isZero is identical to reflect.Value.IsZero. |
| 508 | // TODO: Remove this when Go1.13 is the minimally supported Go version. |
| 509 | func isZero(v reflect.Value) bool { |
| 510 | switch v.Kind() { |
| 511 | case reflect.Bool: |
| 512 | return !v.Bool() |
| 513 | case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: |
| 514 | return v.Int() == 0 |
| 515 | case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: |
| 516 | return v.Uint() == 0 |
| 517 | case reflect.Float32, reflect.Float64: |
| 518 | return math.Float64bits(v.Float()) == 0 |
| 519 | case reflect.Complex64, reflect.Complex128: |
| 520 | c := v.Complex() |
| 521 | return math.Float64bits(real(c)) == 0 && math.Float64bits(imag(c)) == 0 |
| 522 | case reflect.Array: |
| 523 | for i := 0; i < v.Len(); i++ { |
| 524 | if !isZero(v.Index(i)) { |
| 525 | return false |
| 526 | } |
| 527 | } |
| 528 | return true |
| 529 | case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice, reflect.UnsafePointer: |
| 530 | return v.IsNil() |
| 531 | case reflect.String: |
| 532 | return v.Len() == 0 |
| 533 | case reflect.Struct: |
| 534 | for i := 0; i < v.NumField(); i++ { |
| 535 | if !isZero(v.Field(i)) { |
| 536 | return false |
| 537 | } |
| 538 | } |
| 539 | return true |
| 540 | default: |
| 541 | panic(&reflect.ValueError{"reflect.Value.IsZero", v.Kind()}) |
| 542 | } |
| 543 | } |