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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package protoreflect provides interfaces to dynamically manipulate messages.
//
// This package includes type descriptors which describe the structure of types
// defined in proto source files and value interfaces which provide the
// ability to examine and manipulate the contents of messages.
//
//
// Protocol Buffer Descriptors
//
// Protobuf descriptors (e.g., EnumDescriptor or MessageDescriptor)
// are immutable objects that represent protobuf type information.
// They are wrappers around the messages declared in descriptor.proto.
// Protobuf descriptors alone lack any information regarding Go types.
//
// Enums and messages generated by this module implement Enum and ProtoMessage,
// where the Descriptor and ProtoReflect.Descriptor accessors respectively
// return the protobuf descriptor for the values.
//
// The protobuf descriptor interfaces are not meant to be implemented by
// user code since they might need to be extended in the future to support
// additions to the protobuf language.
// The "google.golang.org/protobuf/reflect/protodesc" package converts between
// google.protobuf.DescriptorProto messages and protobuf descriptors.
//
//
// Go Type Descriptors
//
// A type descriptor (e.g., EnumType or MessageType) is a constructor for
// a concrete Go type that represents the associated protobuf descriptor.
// There is commonly a one-to-one relationship between protobuf descriptors and
// Go type descriptors, but it can potentially be a one-to-many relationship.
//
// Enums and messages generated by this module implement Enum and ProtoMessage,
// where the Type and ProtoReflect.Type accessors respectively
// return the protobuf descriptor for the values.
//
// The "google.golang.org/protobuf/types/dynamicpb" package can be used to
// create Go type descriptors from protobuf descriptors.
//
//
// Value Interfaces
//
// The Enum and Message interfaces provide a reflective view over an
// enum or message instance. For enums, it provides the ability to retrieve
// the enum value number for any concrete enum type. For messages, it provides
// the ability to access or manipulate fields of the message.
//
// To convert a proto.Message to a protoreflect.Message, use the
// former's ProtoReflect method. Since the ProtoReflect method is new to the
// v2 message interface, it may not be present on older message implementations.
// The "github.com/golang/protobuf/proto".MessageReflect function can be used
// to obtain a reflective view on older messages.
//
//
// Relationships
//
// The following diagrams demonstrate the relationships between
// various types declared in this package.
//
//
// ┌───────────────────────────────────┐
// V │
// ┌────────────── New(n) ─────────────┐ │
// │ │ │
// │ ┌──── Descriptor() ──┐ │ ┌── Number() ──┐ │
// │ │ V V │ V │
// ╔════════════╗ ╔════════════════╗ ╔════════╗ ╔════════════╗
// ║ EnumType ║ ║ EnumDescriptor ║ ║ Enum ║ ║ EnumNumber ║
// ╚════════════╝ ╚════════════════╝ ╚════════╝ ╚════════════╝
// Λ Λ │ │
// │ └─── Descriptor() ──┘ │
// │ │
// └────────────────── Type() ───────┘
//
// • An EnumType describes a concrete Go enum type.
// It has an EnumDescriptor and can construct an Enum instance.
//
// • An EnumDescriptor describes an abstract protobuf enum type.
//
// • An Enum is a concrete enum instance. Generated enums implement Enum.
//
//
// ┌──────────────── New() ─────────────────┐
// │ │
// │ ┌─── Descriptor() ─────┐ │ ┌── Interface() ───┐
// │ │ V V │ V
// ╔═════════════╗ ╔═══════════════════╗ ╔═════════╗ ╔══════════════╗
// ║ MessageType ║ ║ MessageDescriptor ║ ║ Message ║ ║ ProtoMessage ║
// ╚═════════════╝ ╚═══════════════════╝ ╚═════════╝ ╚══════════════╝
// Λ Λ │ │ Λ │
// │ └──── Descriptor() ────┘ │ └─ ProtoReflect() ─┘
// │ │
// └─────────────────── Type() ─────────┘
//
// • A MessageType describes a concrete Go message type.
// It has a MessageDescriptor and can construct a Message instance.
//
// • A MessageDescriptor describes an abstract protobuf message type.
//
// • A Message is a concrete message instance. Generated messages implement
// ProtoMessage, which can convert to/from a Message.
//
//
// ┌── TypeDescriptor() ──┐ ┌───── Descriptor() ─────┐
// │ V │ V
// ╔═══════════════╗ ╔═════════════════════════╗ ╔═════════════════════╗
// ║ ExtensionType ║ ║ ExtensionTypeDescriptor ║ ║ ExtensionDescriptor ║
// ╚═══════════════╝ ╚═════════════════════════╝ ╚═════════════════════╝
// Λ │ │ Λ │ Λ
// └─────── Type() ───────┘ │ └─── may implement ────┘ │
// │ │
// └────── implements ────────┘
//
// • An ExtensionType describes a concrete Go implementation of an extension.
// It has an ExtensionTypeDescriptor and can convert to/from
// abstract Values and Go values.
//
// • An ExtensionTypeDescriptor is an ExtensionDescriptor
// which also has an ExtensionType.
//
// • An ExtensionDescriptor describes an abstract protobuf extension field and
// may not always be an ExtensionTypeDescriptor.
package protoreflect
import (
"fmt"
"strings"
"google.golang.org/protobuf/encoding/protowire"
"google.golang.org/protobuf/internal/pragma"
)
type doNotImplement pragma.DoNotImplement
// ProtoMessage is the top-level interface that all proto messages implement.
// This is declared in the protoreflect package to avoid a cyclic dependency;
// use the proto.Message type instead, which aliases this type.
type ProtoMessage interface{ ProtoReflect() Message }
// Syntax is the language version of the proto file.
type Syntax syntax
type syntax int8 // keep exact type opaque as the int type may change
const (
Proto2 Syntax = 2
Proto3 Syntax = 3
)
// IsValid reports whether the syntax is valid.
func (s Syntax) IsValid() bool {
switch s {
case Proto2, Proto3:
return true
default:
return false
}
}
// String returns s as a proto source identifier (e.g., "proto2").
func (s Syntax) String() string {
switch s {
case Proto2:
return "proto2"
case Proto3:
return "proto3"
default:
return fmt.Sprintf("<unknown:%d>", s)
}
}
// GoString returns s as a Go source identifier (e.g., "Proto2").
func (s Syntax) GoString() string {
switch s {
case Proto2:
return "Proto2"
case Proto3:
return "Proto3"
default:
return fmt.Sprintf("Syntax(%d)", s)
}
}
// Cardinality determines whether a field is optional, required, or repeated.
type Cardinality cardinality
type cardinality int8 // keep exact type opaque as the int type may change
// Constants as defined by the google.protobuf.Cardinality enumeration.
const (
Optional Cardinality = 1 // appears zero or one times
Required Cardinality = 2 // appears exactly one time; invalid with Proto3
Repeated Cardinality = 3 // appears zero or more times
)
// IsValid reports whether the cardinality is valid.
func (c Cardinality) IsValid() bool {
switch c {
case Optional, Required, Repeated:
return true
default:
return false
}
}
// String returns c as a proto source identifier (e.g., "optional").
func (c Cardinality) String() string {
switch c {
case Optional:
return "optional"
case Required:
return "required"
case Repeated:
return "repeated"
default:
return fmt.Sprintf("<unknown:%d>", c)
}
}
// GoString returns c as a Go source identifier (e.g., "Optional").
func (c Cardinality) GoString() string {
switch c {
case Optional:
return "Optional"
case Required:
return "Required"
case Repeated:
return "Repeated"
default:
return fmt.Sprintf("Cardinality(%d)", c)
}
}
// Kind indicates the basic proto kind of a field.
type Kind kind
type kind int8 // keep exact type opaque as the int type may change
// Constants as defined by the google.protobuf.Field.Kind enumeration.
const (
BoolKind Kind = 8
EnumKind Kind = 14
Int32Kind Kind = 5
Sint32Kind Kind = 17
Uint32Kind Kind = 13
Int64Kind Kind = 3
Sint64Kind Kind = 18
Uint64Kind Kind = 4
Sfixed32Kind Kind = 15
Fixed32Kind Kind = 7
FloatKind Kind = 2
Sfixed64Kind Kind = 16
Fixed64Kind Kind = 6
DoubleKind Kind = 1
StringKind Kind = 9
BytesKind Kind = 12
MessageKind Kind = 11
GroupKind Kind = 10
)
// IsValid reports whether the kind is valid.
func (k Kind) IsValid() bool {
switch k {
case BoolKind, EnumKind,
Int32Kind, Sint32Kind, Uint32Kind,
Int64Kind, Sint64Kind, Uint64Kind,
Sfixed32Kind, Fixed32Kind, FloatKind,
Sfixed64Kind, Fixed64Kind, DoubleKind,
StringKind, BytesKind, MessageKind, GroupKind:
return true
default:
return false
}
}
// String returns k as a proto source identifier (e.g., "bool").
func (k Kind) String() string {
switch k {
case BoolKind:
return "bool"
case EnumKind:
return "enum"
case Int32Kind:
return "int32"
case Sint32Kind:
return "sint32"
case Uint32Kind:
return "uint32"
case Int64Kind:
return "int64"
case Sint64Kind:
return "sint64"
case Uint64Kind:
return "uint64"
case Sfixed32Kind:
return "sfixed32"
case Fixed32Kind:
return "fixed32"
case FloatKind:
return "float"
case Sfixed64Kind:
return "sfixed64"
case Fixed64Kind:
return "fixed64"
case DoubleKind:
return "double"
case StringKind:
return "string"
case BytesKind:
return "bytes"
case MessageKind:
return "message"
case GroupKind:
return "group"
default:
return fmt.Sprintf("<unknown:%d>", k)
}
}
// GoString returns k as a Go source identifier (e.g., "BoolKind").
func (k Kind) GoString() string {
switch k {
case BoolKind:
return "BoolKind"
case EnumKind:
return "EnumKind"
case Int32Kind:
return "Int32Kind"
case Sint32Kind:
return "Sint32Kind"
case Uint32Kind:
return "Uint32Kind"
case Int64Kind:
return "Int64Kind"
case Sint64Kind:
return "Sint64Kind"
case Uint64Kind:
return "Uint64Kind"
case Sfixed32Kind:
return "Sfixed32Kind"
case Fixed32Kind:
return "Fixed32Kind"
case FloatKind:
return "FloatKind"
case Sfixed64Kind:
return "Sfixed64Kind"
case Fixed64Kind:
return "Fixed64Kind"
case DoubleKind:
return "DoubleKind"
case StringKind:
return "StringKind"
case BytesKind:
return "BytesKind"
case MessageKind:
return "MessageKind"
case GroupKind:
return "GroupKind"
default:
return fmt.Sprintf("Kind(%d)", k)
}
}
// FieldNumber is the field number in a message.
type FieldNumber = protowire.Number
// FieldNumbers represent a list of field numbers.
type FieldNumbers interface {
// Len reports the number of fields in the list.
Len() int
// Get returns the ith field number. It panics if out of bounds.
Get(i int) FieldNumber
// Has reports whether n is within the list of fields.
Has(n FieldNumber) bool
doNotImplement
}
// FieldRanges represent a list of field number ranges.
type FieldRanges interface {
// Len reports the number of ranges in the list.
Len() int
// Get returns the ith range. It panics if out of bounds.
Get(i int) [2]FieldNumber // start inclusive; end exclusive
// Has reports whether n is within any of the ranges.
Has(n FieldNumber) bool
doNotImplement
}
// EnumNumber is the numeric value for an enum.
type EnumNumber int32
// EnumRanges represent a list of enum number ranges.
type EnumRanges interface {
// Len reports the number of ranges in the list.
Len() int
// Get returns the ith range. It panics if out of bounds.
Get(i int) [2]EnumNumber // start inclusive; end inclusive
// Has reports whether n is within any of the ranges.
Has(n EnumNumber) bool
doNotImplement
}
// Name is the short name for a proto declaration. This is not the name
// as used in Go source code, which might not be identical to the proto name.
type Name string // e.g., "Kind"
// IsValid reports whether s is a syntactically valid name.
// An empty name is invalid.
func (s Name) IsValid() bool {
return consumeIdent(string(s)) == len(s)
}
// Names represent a list of names.
type Names interface {
// Len reports the number of names in the list.
Len() int
// Get returns the ith name. It panics if out of bounds.
Get(i int) Name
// Has reports whether s matches any names in the list.
Has(s Name) bool
doNotImplement
}
// FullName is a qualified name that uniquely identifies a proto declaration.
// A qualified name is the concatenation of the proto package along with the
// fully-declared name (i.e., name of parent preceding the name of the child),
// with a '.' delimiter placed between each Name.
//
// This should not have any leading or trailing dots.
type FullName string // e.g., "google.protobuf.Field.Kind"
// IsValid reports whether s is a syntactically valid full name.
// An empty full name is invalid.
func (s FullName) IsValid() bool {
i := consumeIdent(string(s))
if i < 0 {
return false
}
for len(s) > i {
if s[i] != '.' {
return false
}
i++
n := consumeIdent(string(s[i:]))
if n < 0 {
return false
}
i += n
}
return true
}
func consumeIdent(s string) (i int) {
if len(s) == 0 || !isLetter(s[i]) {
return -1
}
i++
for len(s) > i && isLetterDigit(s[i]) {
i++
}
return i
}
func isLetter(c byte) bool {
return c == '_' || ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z')
}
func isLetterDigit(c byte) bool {
return isLetter(c) || ('0' <= c && c <= '9')
}
// Name returns the short name, which is the last identifier segment.
// A single segment FullName is the Name itself.
func (n FullName) Name() Name {
if i := strings.LastIndexByte(string(n), '.'); i >= 0 {
return Name(n[i+1:])
}
return Name(n)
}
// Parent returns the full name with the trailing identifier removed.
// A single segment FullName has no parent.
func (n FullName) Parent() FullName {
if i := strings.LastIndexByte(string(n), '.'); i >= 0 {
return n[:i]
}
return ""
}
// Append returns the qualified name appended with the provided short name.
//
// Invariant: n == n.Parent().Append(n.Name()) // assuming n is valid
func (n FullName) Append(s Name) FullName {
if n == "" {
return FullName(s)
}
return n + "." + FullName(s)
}