1// Copyright 2019 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 5package proto 6 7import ( 8 "google.golang.org/protobuf/reflect/protoreflect" 9) 10 11// HasExtension reports whether an extension field is populated. 12// It returns false if m is invalid or if xt does not extend m. 13func HasExtension(m Message, xt protoreflect.ExtensionType) bool { 14 // Treat nil message interface as an empty message; no populated fields. 15 if m == nil { 16 return false 17 } 18 19 // As a special-case, we reports invalid or mismatching descriptors 20 // as always not being populated (since they aren't). 21 if xt == nil || m.ProtoReflect().Descriptor() != xt.TypeDescriptor().ContainingMessage() { 22 return false 23 } 24 25 return m.ProtoReflect().Has(xt.TypeDescriptor()) 26} 27 28// ClearExtension clears an extension field such that subsequent 29// HasExtension calls return false. 30// It panics if m is invalid or if xt does not extend m. 31func ClearExtension(m Message, xt protoreflect.ExtensionType) { 32 m.ProtoReflect().Clear(xt.TypeDescriptor()) 33} 34 35// GetExtension retrieves the value for an extension field. 36// If the field is unpopulated, it returns the default value for 37// scalars and an immutable, empty value for lists or messages. 38// It panics if xt does not extend m. 39func GetExtension(m Message, xt protoreflect.ExtensionType) interface{} { 40 // Treat nil message interface as an empty message; return the default. 41 if m == nil { 42 return xt.InterfaceOf(xt.Zero()) 43 } 44 45 return xt.InterfaceOf(m.ProtoReflect().Get(xt.TypeDescriptor())) 46} 47 48// SetExtension stores the value of an extension field. 49// It panics if m is invalid, xt does not extend m, or if type of v 50// is invalid for the specified extension field. 51func SetExtension(m Message, xt protoreflect.ExtensionType, v interface{}) { 52 xd := xt.TypeDescriptor() 53 pv := xt.ValueOf(v) 54 55 // Specially treat an invalid list, map, or message as clear. 56 isValid := true 57 switch { 58 case xd.IsList(): 59 isValid = pv.List().IsValid() 60 case xd.IsMap(): 61 isValid = pv.Map().IsValid() 62 case xd.Message() != nil: 63 isValid = pv.Message().IsValid() 64 } 65 if !isValid { 66 m.ProtoReflect().Clear(xd) 67 return 68 } 69 70 m.ProtoReflect().Set(xd, pv) 71} 72 73// RangeExtensions iterates over every populated extension field in m in an 74// undefined order, calling f for each extension type and value encountered. 75// It returns immediately if f returns false. 76// While iterating, mutating operations may only be performed 77// on the current extension field. 78func RangeExtensions(m Message, f func(protoreflect.ExtensionType, interface{}) bool) { 79 // Treat nil message interface as an empty message; nothing to range over. 80 if m == nil { 81 return 82 } 83 84 m.ProtoReflect().Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool { 85 if fd.IsExtension() { 86 xt := fd.(protoreflect.ExtensionTypeDescriptor).Type() 87 vi := xt.InterfaceOf(v) 88 return f(xt, vi) 89 } 90 return true 91 }) 92} 93