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// 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 impl
import (
"fmt"
"reflect"
"google.golang.org/protobuf/internal/pragma"
pref "google.golang.org/protobuf/reflect/protoreflect"
)
type reflectMessageInfo struct {
fields map[pref.FieldNumber]*fieldInfo
oneofs map[pref.Name]*oneofInfo
// denseFields is a subset of fields where:
// 0 < fieldDesc.Number() < len(denseFields)
// It provides faster access to the fieldInfo, but may be incomplete.
denseFields []*fieldInfo
// rangeInfos is a list of all fields (not belonging to a oneof) and oneofs.
rangeInfos []interface{} // either *fieldInfo or *oneofInfo
getUnknown func(pointer) pref.RawFields
setUnknown func(pointer, pref.RawFields)
extensionMap func(pointer) *extensionMap
nilMessage atomicNilMessage
}
// makeReflectFuncs generates the set of functions to support reflection.
func (mi *MessageInfo) makeReflectFuncs(t reflect.Type, si structInfo) {
mi.makeKnownFieldsFunc(si)
mi.makeUnknownFieldsFunc(t, si)
mi.makeExtensionFieldsFunc(t, si)
}
// makeKnownFieldsFunc generates functions for operations that can be performed
// on each protobuf message field. It takes in a reflect.Type representing the
// Go struct and matches message fields with struct fields.
//
// This code assumes that the struct is well-formed and panics if there are
// any discrepancies.
func (mi *MessageInfo) makeKnownFieldsFunc(si structInfo) {
mi.fields = map[pref.FieldNumber]*fieldInfo{}
md := mi.Desc
fds := md.Fields()
for i := 0; i < fds.Len(); i++ {
fd := fds.Get(i)
fs := si.fieldsByNumber[fd.Number()]
var fi fieldInfo
switch {
case fd.ContainingOneof() != nil:
fi = fieldInfoForOneof(fd, si.oneofsByName[fd.ContainingOneof().Name()], mi.Exporter, si.oneofWrappersByNumber[fd.Number()])
case fd.IsMap():
fi = fieldInfoForMap(fd, fs, mi.Exporter)
case fd.IsList():
fi = fieldInfoForList(fd, fs, mi.Exporter)
case fd.IsWeak():
fi = fieldInfoForWeakMessage(fd, si.weakOffset)
case fd.Kind() == pref.MessageKind || fd.Kind() == pref.GroupKind:
fi = fieldInfoForMessage(fd, fs, mi.Exporter)
default:
fi = fieldInfoForScalar(fd, fs, mi.Exporter)
}
mi.fields[fd.Number()] = &fi
}
mi.oneofs = map[pref.Name]*oneofInfo{}
for i := 0; i < md.Oneofs().Len(); i++ {
od := md.Oneofs().Get(i)
mi.oneofs[od.Name()] = makeOneofInfo(od, si.oneofsByName[od.Name()], mi.Exporter, si.oneofWrappersByType)
}
mi.denseFields = make([]*fieldInfo, fds.Len()*2)
for i := 0; i < fds.Len(); i++ {
if fd := fds.Get(i); int(fd.Number()) < len(mi.denseFields) {
mi.denseFields[fd.Number()] = mi.fields[fd.Number()]
}
}
for i := 0; i < fds.Len(); {
fd := fds.Get(i)
if od := fd.ContainingOneof(); od != nil {
mi.rangeInfos = append(mi.rangeInfos, mi.oneofs[od.Name()])
i += od.Fields().Len()
} else {
mi.rangeInfos = append(mi.rangeInfos, mi.fields[fd.Number()])
i++
}
}
}
func (mi *MessageInfo) makeUnknownFieldsFunc(t reflect.Type, si structInfo) {
mi.getUnknown = func(pointer) pref.RawFields { return nil }
mi.setUnknown = func(pointer, pref.RawFields) { return }
if si.unknownOffset.IsValid() {
mi.getUnknown = func(p pointer) pref.RawFields {
if p.IsNil() {
return nil
}
rv := p.Apply(si.unknownOffset).AsValueOf(unknownFieldsType)
return pref.RawFields(*rv.Interface().(*[]byte))
}
mi.setUnknown = func(p pointer, b pref.RawFields) {
if p.IsNil() {
panic("invalid SetUnknown on nil Message")
}
rv := p.Apply(si.unknownOffset).AsValueOf(unknownFieldsType)
*rv.Interface().(*[]byte) = []byte(b)
}
} else {
mi.getUnknown = func(pointer) pref.RawFields {
return nil
}
mi.setUnknown = func(p pointer, _ pref.RawFields) {
if p.IsNil() {
panic("invalid SetUnknown on nil Message")
}
}
}
}
func (mi *MessageInfo) makeExtensionFieldsFunc(t reflect.Type, si structInfo) {
if si.extensionOffset.IsValid() {
mi.extensionMap = func(p pointer) *extensionMap {
if p.IsNil() {
return (*extensionMap)(nil)
}
v := p.Apply(si.extensionOffset).AsValueOf(extensionFieldsType)
return (*extensionMap)(v.Interface().(*map[int32]ExtensionField))
}
} else {
mi.extensionMap = func(pointer) *extensionMap {
return (*extensionMap)(nil)
}
}
}
type extensionMap map[int32]ExtensionField
func (m *extensionMap) Range(f func(pref.FieldDescriptor, pref.Value) bool) {
if m != nil {
for _, x := range *m {
xt := x.GetType()
if !f(xt.TypeDescriptor(), x.Value()) {
return
}
}
}
}
func (m *extensionMap) Has(xt pref.ExtensionType) (ok bool) {
if m != nil {
_, ok = (*m)[int32(xt.TypeDescriptor().Number())]
}
return ok
}
func (m *extensionMap) Clear(xt pref.ExtensionType) {
delete(*m, int32(xt.TypeDescriptor().Number()))
}
func (m *extensionMap) Get(xt pref.ExtensionType) pref.Value {
xd := xt.TypeDescriptor()
if m != nil {
if x, ok := (*m)[int32(xd.Number())]; ok {
return x.Value()
}
}
return xt.Zero()
}
func (m *extensionMap) Set(xt pref.ExtensionType, v pref.Value) {
if !xt.IsValidValue(v) {
panic(fmt.Sprintf("%v: assigning invalid value", xt.TypeDescriptor().FullName()))
}
if *m == nil {
*m = make(map[int32]ExtensionField)
}
var x ExtensionField
x.Set(xt, v)
(*m)[int32(xt.TypeDescriptor().Number())] = x
}
func (m *extensionMap) Mutable(xt pref.ExtensionType) pref.Value {
xd := xt.TypeDescriptor()
if xd.Kind() != pref.MessageKind && xd.Kind() != pref.GroupKind && !xd.IsList() && !xd.IsMap() {
panic("invalid Mutable on field with non-composite type")
}
if x, ok := (*m)[int32(xd.Number())]; ok {
return x.Value()
}
v := xt.New()
m.Set(xt, v)
return v
}
// MessageState is a data structure that is nested as the first field in a
// concrete message. It provides a way to implement the ProtoReflect method
// in an allocation-free way without needing to have a shadow Go type generated
// for every message type. This technique only works using unsafe.
//
//
// Example generated code:
//
// type M struct {
// state protoimpl.MessageState
//
// Field1 int32
// Field2 string
// Field3 *BarMessage
// ...
// }
//
// func (m *M) ProtoReflect() protoreflect.Message {
// mi := &file_fizz_buzz_proto_msgInfos[5]
// if protoimpl.UnsafeEnabled && m != nil {
// ms := protoimpl.X.MessageStateOf(Pointer(m))
// if ms.LoadMessageInfo() == nil {
// ms.StoreMessageInfo(mi)
// }
// return ms
// }
// return mi.MessageOf(m)
// }
//
// The MessageState type holds a *MessageInfo, which must be atomically set to
// the message info associated with a given message instance.
// By unsafely converting a *M into a *MessageState, the MessageState object
// has access to all the information needed to implement protobuf reflection.
// It has access to the message info as its first field, and a pointer to the
// MessageState is identical to a pointer to the concrete message value.
//
//
// Requirements:
// • The type M must implement protoreflect.ProtoMessage.
// • The address of m must not be nil.
// • The address of m and the address of m.state must be equal,
// even though they are different Go types.
type MessageState struct {
pragma.NoUnkeyedLiterals
pragma.DoNotCompare
pragma.DoNotCopy
mi *MessageInfo
}
type messageState MessageState
var (
_ pref.Message = (*messageState)(nil)
_ unwrapper = (*messageState)(nil)
)
// messageDataType is a tuple of a pointer to the message data and
// a pointer to the message type. It is a generalized way of providing a
// reflective view over a message instance. The disadvantage of this approach
// is the need to allocate this tuple of 16B.
type messageDataType struct {
p pointer
mi *MessageInfo
}
type (
messageReflectWrapper messageDataType
messageIfaceWrapper messageDataType
)
var (
_ pref.Message = (*messageReflectWrapper)(nil)
_ unwrapper = (*messageReflectWrapper)(nil)
_ pref.ProtoMessage = (*messageIfaceWrapper)(nil)
_ unwrapper = (*messageIfaceWrapper)(nil)
)
// MessageOf returns a reflective view over a message. The input must be a
// pointer to a named Go struct. If the provided type has a ProtoReflect method,
// it must be implemented by calling this method.
func (mi *MessageInfo) MessageOf(m interface{}) pref.Message {
// TODO: Switch the input to be an opaque Pointer.
if reflect.TypeOf(m) != mi.GoReflectType {
panic(fmt.Sprintf("type mismatch: got %T, want %v", m, mi.GoReflectType))
}
p := pointerOfIface(m)
if p.IsNil() {
return mi.nilMessage.Init(mi)
}
return &messageReflectWrapper{p, mi}
}
func (m *messageReflectWrapper) pointer() pointer { return m.p }
func (m *messageReflectWrapper) messageInfo() *MessageInfo { return m.mi }
func (m *messageIfaceWrapper) ProtoReflect() pref.Message {
return (*messageReflectWrapper)(m)
}
func (m *messageIfaceWrapper) protoUnwrap() interface{} {
return m.p.AsIfaceOf(m.mi.GoReflectType.Elem())
}
// checkField verifies that the provided field descriptor is valid.
// Exactly one of the returned values is populated.
func (mi *MessageInfo) checkField(fd pref.FieldDescriptor) (*fieldInfo, pref.ExtensionType) {
var fi *fieldInfo
if n := fd.Number(); 0 < n && int(n) < len(mi.denseFields) {
fi = mi.denseFields[n]
} else {
fi = mi.fields[n]
}
if fi != nil {
if fi.fieldDesc != fd {
panic("mismatching field descriptor")
}
return fi, nil
}
if fd.IsExtension() {
if fd.ContainingMessage().FullName() != mi.Desc.FullName() {
// TODO: Should this be exact containing message descriptor match?
panic("mismatching containing message")
}
if !mi.Desc.ExtensionRanges().Has(fd.Number()) {
panic("invalid extension field")
}
xtd, ok := fd.(pref.ExtensionTypeDescriptor)
if !ok {
panic("extension descriptor does not implement ExtensionTypeDescriptor")
}
return nil, xtd.Type()
}
panic("invalid field descriptor")
}