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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 descfmt provides functionality to format descriptors.
package descfmt
import (
"fmt"
"io"
"reflect"
"strconv"
"strings"
"google.golang.org/protobuf/internal/detrand"
"google.golang.org/protobuf/internal/pragma"
pref "google.golang.org/protobuf/reflect/protoreflect"
)
type list interface {
Len() int
pragma.DoNotImplement
}
func FormatList(s fmt.State, r rune, vs list) {
io.WriteString(s, formatListOpt(vs, true, r == 'v' && (s.Flag('+') || s.Flag('#'))))
}
func formatListOpt(vs list, isRoot, allowMulti bool) string {
start, end := "[", "]"
if isRoot {
var name string
switch vs.(type) {
case pref.Names:
name = "Names"
case pref.FieldNumbers:
name = "FieldNumbers"
case pref.FieldRanges:
name = "FieldRanges"
case pref.EnumRanges:
name = "EnumRanges"
case pref.FileImports:
name = "FileImports"
case pref.Descriptor:
name = reflect.ValueOf(vs).MethodByName("Get").Type().Out(0).Name() + "s"
}
start, end = name+"{", "}"
}
var ss []string
switch vs := vs.(type) {
case pref.Names:
for i := 0; i < vs.Len(); i++ {
ss = append(ss, fmt.Sprint(vs.Get(i)))
}
return start + joinStrings(ss, false) + end
case pref.FieldNumbers:
for i := 0; i < vs.Len(); i++ {
ss = append(ss, fmt.Sprint(vs.Get(i)))
}
return start + joinStrings(ss, false) + end
case pref.FieldRanges:
for i := 0; i < vs.Len(); i++ {
r := vs.Get(i)
if r[0]+1 == r[1] {
ss = append(ss, fmt.Sprintf("%d", r[0]))
} else {
ss = append(ss, fmt.Sprintf("%d:%d", r[0], r[1])) // enum ranges are end exclusive
}
}
return start + joinStrings(ss, false) + end
case pref.EnumRanges:
for i := 0; i < vs.Len(); i++ {
r := vs.Get(i)
if r[0] == r[1] {
ss = append(ss, fmt.Sprintf("%d", r[0]))
} else {
ss = append(ss, fmt.Sprintf("%d:%d", r[0], int64(r[1])+1)) // enum ranges are end inclusive
}
}
return start + joinStrings(ss, false) + end
case pref.FileImports:
for i := 0; i < vs.Len(); i++ {
var rs records
rs.Append(reflect.ValueOf(vs.Get(i)), "Path", "Package", "IsPublic", "IsWeak")
ss = append(ss, "{"+rs.Join()+"}")
}
return start + joinStrings(ss, allowMulti) + end
default:
_, isEnumValue := vs.(pref.EnumValueDescriptors)
for i := 0; i < vs.Len(); i++ {
m := reflect.ValueOf(vs).MethodByName("Get")
v := m.Call([]reflect.Value{reflect.ValueOf(i)})[0].Interface()
ss = append(ss, formatDescOpt(v.(pref.Descriptor), false, allowMulti && !isEnumValue))
}
return start + joinStrings(ss, allowMulti && isEnumValue) + end
}
}
// descriptorAccessors is a list of accessors to print for each descriptor.
//
// Do not print all accessors since some contain redundant information,
// while others are pointers that we do not want to follow since the descriptor
// is actually a cyclic graph.
//
// Using a list allows us to print the accessors in a sensible order.
var descriptorAccessors = map[reflect.Type][]string{
reflect.TypeOf((*pref.FileDescriptor)(nil)).Elem(): {"Path", "Package", "Imports", "Messages", "Enums", "Extensions", "Services"},
reflect.TypeOf((*pref.MessageDescriptor)(nil)).Elem(): {"IsMapEntry", "Fields", "Oneofs", "ReservedNames", "ReservedRanges", "RequiredNumbers", "ExtensionRanges", "Messages", "Enums", "Extensions"},
reflect.TypeOf((*pref.FieldDescriptor)(nil)).Elem(): {"Number", "Cardinality", "Kind", "HasJSONName", "JSONName", "IsPacked", "IsExtension", "IsWeak", "IsList", "IsMap", "MapKey", "MapValue", "HasDefault", "Default", "ContainingOneof", "ContainingMessage", "Message", "Enum"},
reflect.TypeOf((*pref.OneofDescriptor)(nil)).Elem(): {"Fields"}, // not directly used; must keep in sync with formatDescOpt
reflect.TypeOf((*pref.EnumDescriptor)(nil)).Elem(): {"Values", "ReservedNames", "ReservedRanges"},
reflect.TypeOf((*pref.EnumValueDescriptor)(nil)).Elem(): {"Number"},
reflect.TypeOf((*pref.ServiceDescriptor)(nil)).Elem(): {"Methods"},
reflect.TypeOf((*pref.MethodDescriptor)(nil)).Elem(): {"Input", "Output", "IsStreamingClient", "IsStreamingServer"},
}
func FormatDesc(s fmt.State, r rune, t pref.Descriptor) {
io.WriteString(s, formatDescOpt(t, true, r == 'v' && (s.Flag('+') || s.Flag('#'))))
}
func formatDescOpt(t pref.Descriptor, isRoot, allowMulti bool) string {
rv := reflect.ValueOf(t)
rt := rv.MethodByName("ProtoType").Type().In(0)
start, end := "{", "}"
if isRoot {
start = rt.Name() + "{"
}
_, isFile := t.(pref.FileDescriptor)
rs := records{allowMulti: allowMulti}
if t.IsPlaceholder() {
if isFile {
rs.Append(rv, "Path", "Package", "IsPlaceholder")
} else {
rs.Append(rv, "FullName", "IsPlaceholder")
}
} else {
switch {
case isFile:
rs.Append(rv, "Syntax")
case isRoot:
rs.Append(rv, "Syntax", "FullName")
default:
rs.Append(rv, "Name")
}
switch t := t.(type) {
case pref.FieldDescriptor:
for _, s := range descriptorAccessors[rt] {
switch s {
case "MapKey":
if k := t.MapKey(); k != nil {
rs.recs = append(rs.recs, [2]string{"MapKey", k.Kind().String()})
}
case "MapValue":
if v := t.MapValue(); v != nil {
switch v.Kind() {
case pref.EnumKind:
rs.recs = append(rs.recs, [2]string{"MapValue", string(v.Enum().FullName())})
case pref.MessageKind, pref.GroupKind:
rs.recs = append(rs.recs, [2]string{"MapValue", string(v.Message().FullName())})
default:
rs.recs = append(rs.recs, [2]string{"MapValue", v.Kind().String()})
}
}
case "ContainingOneof":
if od := t.ContainingOneof(); od != nil {
rs.recs = append(rs.recs, [2]string{"Oneof", string(od.Name())})
}
case "ContainingMessage":
if t.IsExtension() {
rs.recs = append(rs.recs, [2]string{"Extendee", string(t.ContainingMessage().FullName())})
}
case "Message":
if !t.IsMap() {
rs.Append(rv, s)
}
default:
rs.Append(rv, s)
}
}
case pref.OneofDescriptor:
var ss []string
fs := t.Fields()
for i := 0; i < fs.Len(); i++ {
ss = append(ss, string(fs.Get(i).Name()))
}
if len(ss) > 0 {
rs.recs = append(rs.recs, [2]string{"Fields", "[" + joinStrings(ss, false) + "]"})
}
default:
rs.Append(rv, descriptorAccessors[rt]...)
}
if rv.MethodByName("GoType").IsValid() {
rs.Append(rv, "GoType")
}
}
return start + rs.Join() + end
}
type records struct {
recs [][2]string
allowMulti bool
}
func (rs *records) Append(v reflect.Value, accessors ...string) {
for _, a := range accessors {
var rv reflect.Value
if m := v.MethodByName(a); m.IsValid() {
rv = m.Call(nil)[0]
}
if v.Kind() == reflect.Struct && !rv.IsValid() {
rv = v.FieldByName(a)
}
if !rv.IsValid() {
panic(fmt.Sprintf("unknown accessor: %v.%s", v.Type(), a))
}
if _, ok := rv.Interface().(pref.Value); ok {
rv = rv.MethodByName("Interface").Call(nil)[0]
if !rv.IsNil() {
rv = rv.Elem()
}
}
// Ignore zero values.
var isZero bool
switch rv.Kind() {
case reflect.Interface, reflect.Slice:
isZero = rv.IsNil()
case reflect.Bool:
isZero = rv.Bool() == false
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
isZero = rv.Int() == 0
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
isZero = rv.Uint() == 0
case reflect.String:
isZero = rv.String() == ""
}
if n, ok := rv.Interface().(list); ok {
isZero = n.Len() == 0
}
if isZero {
continue
}
// Format the value.
var s string
v := rv.Interface()
switch v := v.(type) {
case list:
s = formatListOpt(v, false, rs.allowMulti)
case pref.FieldDescriptor, pref.OneofDescriptor, pref.EnumValueDescriptor, pref.MethodDescriptor:
s = string(v.(pref.Descriptor).Name())
case pref.Descriptor:
s = string(v.FullName())
case string:
s = strconv.Quote(v)
case []byte:
s = fmt.Sprintf("%q", v)
default:
s = fmt.Sprint(v)
}
rs.recs = append(rs.recs, [2]string{a, s})
}
}
func (rs *records) Join() string {
var ss []string
// In single line mode, simply join all records with commas.
if !rs.allowMulti {
for _, r := range rs.recs {
ss = append(ss, r[0]+formatColon(0)+r[1])
}
return joinStrings(ss, false)
}
// In allowMulti line mode, align single line records for more readable output.
var maxLen int
flush := func(i int) {
for _, r := range rs.recs[len(ss):i] {
ss = append(ss, r[0]+formatColon(maxLen-len(r[0]))+r[1])
}
maxLen = 0
}
for i, r := range rs.recs {
if isMulti := strings.Contains(r[1], "\n"); isMulti {
flush(i)
ss = append(ss, r[0]+formatColon(0)+strings.Join(strings.Split(r[1], "\n"), "\n\t"))
} else if maxLen < len(r[0]) {
maxLen = len(r[0])
}
}
flush(len(rs.recs))
return joinStrings(ss, true)
}
func formatColon(padding int) string {
// Deliberately introduce instability into the debug output to
// discourage users from performing string comparisons.
// This provides us flexibility to change the output in the future.
if detrand.Bool() {
return ":" + strings.Repeat(" ", 1+padding) // use non-breaking spaces (U+00a0)
} else {
return ":" + strings.Repeat(" ", 1+padding) // use regular spaces (U+0020)
}
}
func joinStrings(ss []string, isMulti bool) string {
if len(ss) == 0 {
return ""
}
if isMulti {
return "\n\t" + strings.Join(ss, "\n\t") + "\n"
}
return strings.Join(ss, ", ")
}