amit.ghosh | 258d14c | 2020-10-02 15:13:38 +0200 | [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 protoreflect provides interfaces to dynamically manipulate messages. |
| 6 | // |
| 7 | // This package includes type descriptors which describe the structure of types |
| 8 | // defined in proto source files and value interfaces which provide the |
| 9 | // ability to examine and manipulate the contents of messages. |
| 10 | // |
| 11 | // |
| 12 | // Protocol Buffer Descriptors |
| 13 | // |
| 14 | // Protobuf descriptors (e.g., EnumDescriptor or MessageDescriptor) |
| 15 | // are immutable objects that represent protobuf type information. |
| 16 | // They are wrappers around the messages declared in descriptor.proto. |
| 17 | // Protobuf descriptors alone lack any information regarding Go types. |
| 18 | // |
| 19 | // Enums and messages generated by this module implement Enum and ProtoMessage, |
| 20 | // where the Descriptor and ProtoReflect.Descriptor accessors respectively |
| 21 | // return the protobuf descriptor for the values. |
| 22 | // |
| 23 | // The protobuf descriptor interfaces are not meant to be implemented by |
| 24 | // user code since they might need to be extended in the future to support |
| 25 | // additions to the protobuf language. |
| 26 | // The "google.golang.org/protobuf/reflect/protodesc" package converts between |
| 27 | // google.protobuf.DescriptorProto messages and protobuf descriptors. |
| 28 | // |
| 29 | // |
| 30 | // Go Type Descriptors |
| 31 | // |
| 32 | // A type descriptor (e.g., EnumType or MessageType) is a constructor for |
| 33 | // a concrete Go type that represents the associated protobuf descriptor. |
| 34 | // There is commonly a one-to-one relationship between protobuf descriptors and |
| 35 | // Go type descriptors, but it can potentially be a one-to-many relationship. |
| 36 | // |
| 37 | // Enums and messages generated by this module implement Enum and ProtoMessage, |
| 38 | // where the Type and ProtoReflect.Type accessors respectively |
| 39 | // return the protobuf descriptor for the values. |
| 40 | // |
| 41 | // The "google.golang.org/protobuf/types/dynamicpb" package can be used to |
| 42 | // create Go type descriptors from protobuf descriptors. |
| 43 | // |
| 44 | // |
| 45 | // Value Interfaces |
| 46 | // |
| 47 | // The Enum and Message interfaces provide a reflective view over an |
| 48 | // enum or message instance. For enums, it provides the ability to retrieve |
| 49 | // the enum value number for any concrete enum type. For messages, it provides |
| 50 | // the ability to access or manipulate fields of the message. |
| 51 | // |
| 52 | // To convert a proto.Message to a protoreflect.Message, use the |
| 53 | // former's ProtoReflect method. Since the ProtoReflect method is new to the |
| 54 | // v2 message interface, it may not be present on older message implementations. |
| 55 | // The "github.com/golang/protobuf/proto".MessageReflect function can be used |
| 56 | // to obtain a reflective view on older messages. |
| 57 | // |
| 58 | // |
| 59 | // Relationships |
| 60 | // |
| 61 | // The following diagrams demonstrate the relationships between |
| 62 | // various types declared in this package. |
| 63 | // |
| 64 | // |
| 65 | // ┌───────────────────────────────────┐ |
| 66 | // V │ |
| 67 | // ┌────────────── New(n) ─────────────┐ │ |
| 68 | // │ │ │ |
| 69 | // │ ┌──── Descriptor() ──┐ │ ┌── Number() ──┐ │ |
| 70 | // │ │ V V │ V │ |
| 71 | // ╔════════════╗ ╔════════════════╗ ╔════════╗ ╔════════════╗ |
| 72 | // ║ EnumType ║ ║ EnumDescriptor ║ ║ Enum ║ ║ EnumNumber ║ |
| 73 | // ╚════════════╝ ╚════════════════╝ ╚════════╝ ╚════════════╝ |
| 74 | // Λ Λ │ │ |
| 75 | // │ └─── Descriptor() ──┘ │ |
| 76 | // │ │ |
| 77 | // └────────────────── Type() ───────┘ |
| 78 | // |
| 79 | // • An EnumType describes a concrete Go enum type. |
| 80 | // It has an EnumDescriptor and can construct an Enum instance. |
| 81 | // |
| 82 | // • An EnumDescriptor describes an abstract protobuf enum type. |
| 83 | // |
| 84 | // • An Enum is a concrete enum instance. Generated enums implement Enum. |
| 85 | // |
| 86 | // |
| 87 | // ┌──────────────── New() ─────────────────┐ |
| 88 | // │ │ |
| 89 | // │ ┌─── Descriptor() ─────┐ │ ┌── Interface() ───┐ |
| 90 | // │ │ V V │ V |
| 91 | // ╔═════════════╗ ╔═══════════════════╗ ╔═════════╗ ╔══════════════╗ |
| 92 | // ║ MessageType ║ ║ MessageDescriptor ║ ║ Message ║ ║ ProtoMessage ║ |
| 93 | // ╚═════════════╝ ╚═══════════════════╝ ╚═════════╝ ╚══════════════╝ |
| 94 | // Λ Λ │ │ Λ │ |
| 95 | // │ └──── Descriptor() ────┘ │ └─ ProtoReflect() ─┘ |
| 96 | // │ │ |
| 97 | // └─────────────────── Type() ─────────┘ |
| 98 | // |
| 99 | // • A MessageType describes a concrete Go message type. |
| 100 | // It has a MessageDescriptor and can construct a Message instance. |
| 101 | // |
| 102 | // • A MessageDescriptor describes an abstract protobuf message type. |
| 103 | // |
| 104 | // • A Message is a concrete message instance. Generated messages implement |
| 105 | // ProtoMessage, which can convert to/from a Message. |
| 106 | // |
| 107 | // |
| 108 | // ┌── TypeDescriptor() ──┐ ┌───── Descriptor() ─────┐ |
| 109 | // │ V │ V |
| 110 | // ╔═══════════════╗ ╔═════════════════════════╗ ╔═════════════════════╗ |
| 111 | // ║ ExtensionType ║ ║ ExtensionTypeDescriptor ║ ║ ExtensionDescriptor ║ |
| 112 | // ╚═══════════════╝ ╚═════════════════════════╝ ╚═════════════════════╝ |
| 113 | // Λ │ │ Λ │ Λ |
| 114 | // └─────── Type() ───────┘ │ └─── may implement ────┘ │ |
| 115 | // │ │ |
| 116 | // └────── implements ────────┘ |
| 117 | // |
| 118 | // • An ExtensionType describes a concrete Go implementation of an extension. |
| 119 | // It has an ExtensionTypeDescriptor and can convert to/from |
| 120 | // abstract Values and Go values. |
| 121 | // |
| 122 | // • An ExtensionTypeDescriptor is an ExtensionDescriptor |
| 123 | // which also has an ExtensionType. |
| 124 | // |
| 125 | // • An ExtensionDescriptor describes an abstract protobuf extension field and |
| 126 | // may not always be an ExtensionTypeDescriptor. |
| 127 | package protoreflect |
| 128 | |
| 129 | import ( |
| 130 | "fmt" |
| 131 | "regexp" |
| 132 | "strings" |
| 133 | |
| 134 | "google.golang.org/protobuf/encoding/protowire" |
| 135 | "google.golang.org/protobuf/internal/pragma" |
| 136 | ) |
| 137 | |
| 138 | type doNotImplement pragma.DoNotImplement |
| 139 | |
| 140 | // ProtoMessage is the top-level interface that all proto messages implement. |
| 141 | // This is declared in the protoreflect package to avoid a cyclic dependency; |
| 142 | // use the proto.Message type instead, which aliases this type. |
| 143 | type ProtoMessage interface{ ProtoReflect() Message } |
| 144 | |
| 145 | // Syntax is the language version of the proto file. |
| 146 | type Syntax syntax |
| 147 | |
| 148 | type syntax int8 // keep exact type opaque as the int type may change |
| 149 | |
| 150 | const ( |
| 151 | Proto2 Syntax = 2 |
| 152 | Proto3 Syntax = 3 |
| 153 | ) |
| 154 | |
| 155 | // IsValid reports whether the syntax is valid. |
| 156 | func (s Syntax) IsValid() bool { |
| 157 | switch s { |
| 158 | case Proto2, Proto3: |
| 159 | return true |
| 160 | default: |
| 161 | return false |
| 162 | } |
| 163 | } |
| 164 | |
| 165 | // String returns s as a proto source identifier (e.g., "proto2"). |
| 166 | func (s Syntax) String() string { |
| 167 | switch s { |
| 168 | case Proto2: |
| 169 | return "proto2" |
| 170 | case Proto3: |
| 171 | return "proto3" |
| 172 | default: |
| 173 | return fmt.Sprintf("<unknown:%d>", s) |
| 174 | } |
| 175 | } |
| 176 | |
| 177 | // GoString returns s as a Go source identifier (e.g., "Proto2"). |
| 178 | func (s Syntax) GoString() string { |
| 179 | switch s { |
| 180 | case Proto2: |
| 181 | return "Proto2" |
| 182 | case Proto3: |
| 183 | return "Proto3" |
| 184 | default: |
| 185 | return fmt.Sprintf("Syntax(%d)", s) |
| 186 | } |
| 187 | } |
| 188 | |
| 189 | // Cardinality determines whether a field is optional, required, or repeated. |
| 190 | type Cardinality cardinality |
| 191 | |
| 192 | type cardinality int8 // keep exact type opaque as the int type may change |
| 193 | |
| 194 | // Constants as defined by the google.protobuf.Cardinality enumeration. |
| 195 | const ( |
| 196 | Optional Cardinality = 1 // appears zero or one times |
| 197 | Required Cardinality = 2 // appears exactly one time; invalid with Proto3 |
| 198 | Repeated Cardinality = 3 // appears zero or more times |
| 199 | ) |
| 200 | |
| 201 | // IsValid reports whether the cardinality is valid. |
| 202 | func (c Cardinality) IsValid() bool { |
| 203 | switch c { |
| 204 | case Optional, Required, Repeated: |
| 205 | return true |
| 206 | default: |
| 207 | return false |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | // String returns c as a proto source identifier (e.g., "optional"). |
| 212 | func (c Cardinality) String() string { |
| 213 | switch c { |
| 214 | case Optional: |
| 215 | return "optional" |
| 216 | case Required: |
| 217 | return "required" |
| 218 | case Repeated: |
| 219 | return "repeated" |
| 220 | default: |
| 221 | return fmt.Sprintf("<unknown:%d>", c) |
| 222 | } |
| 223 | } |
| 224 | |
| 225 | // GoString returns c as a Go source identifier (e.g., "Optional"). |
| 226 | func (c Cardinality) GoString() string { |
| 227 | switch c { |
| 228 | case Optional: |
| 229 | return "Optional" |
| 230 | case Required: |
| 231 | return "Required" |
| 232 | case Repeated: |
| 233 | return "Repeated" |
| 234 | default: |
| 235 | return fmt.Sprintf("Cardinality(%d)", c) |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | // Kind indicates the basic proto kind of a field. |
| 240 | type Kind kind |
| 241 | |
| 242 | type kind int8 // keep exact type opaque as the int type may change |
| 243 | |
| 244 | // Constants as defined by the google.protobuf.Field.Kind enumeration. |
| 245 | const ( |
| 246 | BoolKind Kind = 8 |
| 247 | EnumKind Kind = 14 |
| 248 | Int32Kind Kind = 5 |
| 249 | Sint32Kind Kind = 17 |
| 250 | Uint32Kind Kind = 13 |
| 251 | Int64Kind Kind = 3 |
| 252 | Sint64Kind Kind = 18 |
| 253 | Uint64Kind Kind = 4 |
| 254 | Sfixed32Kind Kind = 15 |
| 255 | Fixed32Kind Kind = 7 |
| 256 | FloatKind Kind = 2 |
| 257 | Sfixed64Kind Kind = 16 |
| 258 | Fixed64Kind Kind = 6 |
| 259 | DoubleKind Kind = 1 |
| 260 | StringKind Kind = 9 |
| 261 | BytesKind Kind = 12 |
| 262 | MessageKind Kind = 11 |
| 263 | GroupKind Kind = 10 |
| 264 | ) |
| 265 | |
| 266 | // IsValid reports whether the kind is valid. |
| 267 | func (k Kind) IsValid() bool { |
| 268 | switch k { |
| 269 | case BoolKind, EnumKind, |
| 270 | Int32Kind, Sint32Kind, Uint32Kind, |
| 271 | Int64Kind, Sint64Kind, Uint64Kind, |
| 272 | Sfixed32Kind, Fixed32Kind, FloatKind, |
| 273 | Sfixed64Kind, Fixed64Kind, DoubleKind, |
| 274 | StringKind, BytesKind, MessageKind, GroupKind: |
| 275 | return true |
| 276 | default: |
| 277 | return false |
| 278 | } |
| 279 | } |
| 280 | |
| 281 | // String returns k as a proto source identifier (e.g., "bool"). |
| 282 | func (k Kind) String() string { |
| 283 | switch k { |
| 284 | case BoolKind: |
| 285 | return "bool" |
| 286 | case EnumKind: |
| 287 | return "enum" |
| 288 | case Int32Kind: |
| 289 | return "int32" |
| 290 | case Sint32Kind: |
| 291 | return "sint32" |
| 292 | case Uint32Kind: |
| 293 | return "uint32" |
| 294 | case Int64Kind: |
| 295 | return "int64" |
| 296 | case Sint64Kind: |
| 297 | return "sint64" |
| 298 | case Uint64Kind: |
| 299 | return "uint64" |
| 300 | case Sfixed32Kind: |
| 301 | return "sfixed32" |
| 302 | case Fixed32Kind: |
| 303 | return "fixed32" |
| 304 | case FloatKind: |
| 305 | return "float" |
| 306 | case Sfixed64Kind: |
| 307 | return "sfixed64" |
| 308 | case Fixed64Kind: |
| 309 | return "fixed64" |
| 310 | case DoubleKind: |
| 311 | return "double" |
| 312 | case StringKind: |
| 313 | return "string" |
| 314 | case BytesKind: |
| 315 | return "bytes" |
| 316 | case MessageKind: |
| 317 | return "message" |
| 318 | case GroupKind: |
| 319 | return "group" |
| 320 | default: |
| 321 | return fmt.Sprintf("<unknown:%d>", k) |
| 322 | } |
| 323 | } |
| 324 | |
| 325 | // GoString returns k as a Go source identifier (e.g., "BoolKind"). |
| 326 | func (k Kind) GoString() string { |
| 327 | switch k { |
| 328 | case BoolKind: |
| 329 | return "BoolKind" |
| 330 | case EnumKind: |
| 331 | return "EnumKind" |
| 332 | case Int32Kind: |
| 333 | return "Int32Kind" |
| 334 | case Sint32Kind: |
| 335 | return "Sint32Kind" |
| 336 | case Uint32Kind: |
| 337 | return "Uint32Kind" |
| 338 | case Int64Kind: |
| 339 | return "Int64Kind" |
| 340 | case Sint64Kind: |
| 341 | return "Sint64Kind" |
| 342 | case Uint64Kind: |
| 343 | return "Uint64Kind" |
| 344 | case Sfixed32Kind: |
| 345 | return "Sfixed32Kind" |
| 346 | case Fixed32Kind: |
| 347 | return "Fixed32Kind" |
| 348 | case FloatKind: |
| 349 | return "FloatKind" |
| 350 | case Sfixed64Kind: |
| 351 | return "Sfixed64Kind" |
| 352 | case Fixed64Kind: |
| 353 | return "Fixed64Kind" |
| 354 | case DoubleKind: |
| 355 | return "DoubleKind" |
| 356 | case StringKind: |
| 357 | return "StringKind" |
| 358 | case BytesKind: |
| 359 | return "BytesKind" |
| 360 | case MessageKind: |
| 361 | return "MessageKind" |
| 362 | case GroupKind: |
| 363 | return "GroupKind" |
| 364 | default: |
| 365 | return fmt.Sprintf("Kind(%d)", k) |
| 366 | } |
| 367 | } |
| 368 | |
| 369 | // FieldNumber is the field number in a message. |
| 370 | type FieldNumber = protowire.Number |
| 371 | |
| 372 | // FieldNumbers represent a list of field numbers. |
| 373 | type FieldNumbers interface { |
| 374 | // Len reports the number of fields in the list. |
| 375 | Len() int |
| 376 | // Get returns the ith field number. It panics if out of bounds. |
| 377 | Get(i int) FieldNumber |
| 378 | // Has reports whether n is within the list of fields. |
| 379 | Has(n FieldNumber) bool |
| 380 | |
| 381 | doNotImplement |
| 382 | } |
| 383 | |
| 384 | // FieldRanges represent a list of field number ranges. |
| 385 | type FieldRanges interface { |
| 386 | // Len reports the number of ranges in the list. |
| 387 | Len() int |
| 388 | // Get returns the ith range. It panics if out of bounds. |
| 389 | Get(i int) [2]FieldNumber // start inclusive; end exclusive |
| 390 | // Has reports whether n is within any of the ranges. |
| 391 | Has(n FieldNumber) bool |
| 392 | |
| 393 | doNotImplement |
| 394 | } |
| 395 | |
| 396 | // EnumNumber is the numeric value for an enum. |
| 397 | type EnumNumber int32 |
| 398 | |
| 399 | // EnumRanges represent a list of enum number ranges. |
| 400 | type EnumRanges interface { |
| 401 | // Len reports the number of ranges in the list. |
| 402 | Len() int |
| 403 | // Get returns the ith range. It panics if out of bounds. |
| 404 | Get(i int) [2]EnumNumber // start inclusive; end inclusive |
| 405 | // Has reports whether n is within any of the ranges. |
| 406 | Has(n EnumNumber) bool |
| 407 | |
| 408 | doNotImplement |
| 409 | } |
| 410 | |
| 411 | var ( |
| 412 | regexName = regexp.MustCompile(`^[_a-zA-Z][_a-zA-Z0-9]*$`) |
| 413 | regexFullName = regexp.MustCompile(`^[_a-zA-Z][_a-zA-Z0-9]*(\.[_a-zA-Z][_a-zA-Z0-9]*)*$`) |
| 414 | ) |
| 415 | |
| 416 | // Name is the short name for a proto declaration. This is not the name |
| 417 | // as used in Go source code, which might not be identical to the proto name. |
| 418 | type Name string // e.g., "Kind" |
| 419 | |
| 420 | // IsValid reports whether n is a syntactically valid name. |
| 421 | // An empty name is invalid. |
| 422 | func (n Name) IsValid() bool { |
| 423 | return regexName.MatchString(string(n)) |
| 424 | } |
| 425 | |
| 426 | // Names represent a list of names. |
| 427 | type Names interface { |
| 428 | // Len reports the number of names in the list. |
| 429 | Len() int |
| 430 | // Get returns the ith name. It panics if out of bounds. |
| 431 | Get(i int) Name |
| 432 | // Has reports whether s matches any names in the list. |
| 433 | Has(s Name) bool |
| 434 | |
| 435 | doNotImplement |
| 436 | } |
| 437 | |
| 438 | // FullName is a qualified name that uniquely identifies a proto declaration. |
| 439 | // A qualified name is the concatenation of the proto package along with the |
| 440 | // fully-declared name (i.e., name of parent preceding the name of the child), |
| 441 | // with a '.' delimiter placed between each Name. |
| 442 | // |
| 443 | // This should not have any leading or trailing dots. |
| 444 | type FullName string // e.g., "google.protobuf.Field.Kind" |
| 445 | |
| 446 | // IsValid reports whether n is a syntactically valid full name. |
| 447 | // An empty full name is invalid. |
| 448 | func (n FullName) IsValid() bool { |
| 449 | return regexFullName.MatchString(string(n)) |
| 450 | } |
| 451 | |
| 452 | // Name returns the short name, which is the last identifier segment. |
| 453 | // A single segment FullName is the Name itself. |
| 454 | func (n FullName) Name() Name { |
| 455 | if i := strings.LastIndexByte(string(n), '.'); i >= 0 { |
| 456 | return Name(n[i+1:]) |
| 457 | } |
| 458 | return Name(n) |
| 459 | } |
| 460 | |
| 461 | // Parent returns the full name with the trailing identifier removed. |
| 462 | // A single segment FullName has no parent. |
| 463 | func (n FullName) Parent() FullName { |
| 464 | if i := strings.LastIndexByte(string(n), '.'); i >= 0 { |
| 465 | return n[:i] |
| 466 | } |
| 467 | return "" |
| 468 | } |
| 469 | |
| 470 | // Append returns the qualified name appended with the provided short name. |
| 471 | // |
| 472 | // Invariant: n == n.Parent().Append(n.Name()) // assuming n is valid |
| 473 | func (n FullName) Append(s Name) FullName { |
| 474 | if n == "" { |
| 475 | return FullName(s) |
| 476 | } |
| 477 | return n + "." + FullName(s) |
| 478 | } |