Source File
extension.go
Belonging Package
google.golang.org/protobuf/proto
// Copyright 2019 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 proto
import (
)
// HasExtension reports whether an extension field is populated.
// It returns false if m is invalid or if xt does not extend m.
func ( Message, protoreflect.ExtensionType) bool {
// Treat nil message interface or descriptor as an empty message; no populated
// fields.
if == nil || == nil {
return false
}
// As a special-case, we reports invalid or mismatching descriptors
// as always not being populated (since they aren't).
:= .ProtoReflect()
:= .TypeDescriptor()
if .Descriptor() != .ContainingMessage() {
return false
}
return .Has()
}
// ClearExtension clears an extension field such that subsequent
// [HasExtension] calls return false.
// It panics if m is invalid or if xt does not extend m.
func ( Message, protoreflect.ExtensionType) {
.ProtoReflect().Clear(.TypeDescriptor())
}
// GetExtension retrieves the value for an extension field.
// If the field is unpopulated, it returns the default value for
// scalars and an immutable, empty value for lists or messages.
// It panics if xt does not extend m.
//
// The type of the value is dependent on the field type of the extension.
// For extensions generated by protoc-gen-go, the Go type is as follows:
//
// ╔═══════════════════╤═════════════════════════╗
// ║ Go type │ Protobuf kind ║
// ╠═══════════════════╪═════════════════════════╣
// ║ bool │ bool ║
// ║ int32 │ int32, sint32, sfixed32 ║
// ║ int64 │ int64, sint64, sfixed64 ║
// ║ uint32 │ uint32, fixed32 ║
// ║ uint64 │ uint64, fixed64 ║
// ║ float32 │ float ║
// ║ float64 │ double ║
// ║ string │ string ║
// ║ []byte │ bytes ║
// ║ protoreflect.Enum │ enum ║
// ║ proto.Message │ message, group ║
// ╚═══════════════════╧═════════════════════════╝
//
// The protoreflect.Enum and proto.Message types are the concrete Go type
// associated with the named enum or message. Repeated fields are represented
// using a Go slice of the base element type.
//
// If a generated extension descriptor variable is directly passed to
// GetExtension, then the call should be followed immediately by a
// type assertion to the expected output value. For example:
//
// mm := proto.GetExtension(m, foopb.E_MyExtension).(*foopb.MyMessage)
//
// This pattern enables static analysis tools to verify that the asserted type
// matches the Go type associated with the extension field and
// also enables a possible future migration to a type-safe extension API.
//
// Since singular messages are the most common extension type, the pattern of
// calling HasExtension followed by GetExtension may be simplified to:
//
// if mm := proto.GetExtension(m, foopb.E_MyExtension).(*foopb.MyMessage); mm != nil {
// ... // make use of mm
// }
//
// The mm variable is non-nil if and only if HasExtension reports true.
func ( Message, protoreflect.ExtensionType) any {
// Treat nil message interface as an empty message; return the default.
if == nil {
return .InterfaceOf(.Zero())
}
return .InterfaceOf(.ProtoReflect().Get(.TypeDescriptor()))
}
// SetExtension stores the value of an extension field.
// It panics if m is invalid, xt does not extend m, or if type of v
// is invalid for the specified extension field.
//
// The type of the value is dependent on the field type of the extension.
// For extensions generated by protoc-gen-go, the Go type is as follows:
//
// ╔═══════════════════╤═════════════════════════╗
// ║ Go type │ Protobuf kind ║
// ╠═══════════════════╪═════════════════════════╣
// ║ bool │ bool ║
// ║ int32 │ int32, sint32, sfixed32 ║
// ║ int64 │ int64, sint64, sfixed64 ║
// ║ uint32 │ uint32, fixed32 ║
// ║ uint64 │ uint64, fixed64 ║
// ║ float32 │ float ║
// ║ float64 │ double ║
// ║ string │ string ║
// ║ []byte │ bytes ║
// ║ protoreflect.Enum │ enum ║
// ║ proto.Message │ message, group ║
// ╚═══════════════════╧═════════════════════════╝
//
// The protoreflect.Enum and proto.Message types are the concrete Go type
// associated with the named enum or message. Repeated fields are represented
// using a Go slice of the base element type.
//
// If a generated extension descriptor variable is directly passed to
// SetExtension (e.g., foopb.E_MyExtension), then the value should be a
// concrete type that matches the expected Go type for the extension descriptor
// so that static analysis tools can verify type correctness.
// This also enables a possible future migration to a type-safe extension API.
func ( Message, protoreflect.ExtensionType, any) {
:= .TypeDescriptor()
:= .ValueOf()
// Specially treat an invalid list, map, or message as clear.
:= true
switch {
case .IsList():
= .List().IsValid()
case .IsMap():
= .Map().IsValid()
case .Message() != nil:
= .Message().IsValid()
}
if ! {
.ProtoReflect().Clear()
return
}
.ProtoReflect().Set(, )
}
// RangeExtensions iterates over every populated extension field in m in an
// undefined order, calling f for each extension type and value encountered.
// It returns immediately if f returns false.
// While iterating, mutating operations may only be performed
// on the current extension field.
func ( Message, func(protoreflect.ExtensionType, any) bool) {
// Treat nil message interface as an empty message; nothing to range over.
if == nil {
return
}
.ProtoReflect().Range(func( protoreflect.FieldDescriptor, protoreflect.Value) bool {
if .IsExtension() {
:= .(protoreflect.ExtensionTypeDescriptor).Type()
:= .InterfaceOf()
return (, )
}
return true
})
}
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