gotosocial/vendor/github.com/abema/go-mp4/field.go

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package mp4
import (
"fmt"
"os"
"reflect"
"sort"
"strconv"
"strings"
)
type (
stringType uint8
fieldFlag uint16
)
const (
stringType_C stringType = iota
stringType_C_P
fieldString fieldFlag = 1 << iota // 0
fieldExtend // 1
fieldDec // 2
fieldHex // 3
fieldISO639_2 // 4
fieldUUID // 5
fieldHidden // 6
fieldOptDynamic // 7
fieldVarint // 8
fieldSizeDynamic // 9
fieldLengthDynamic // 10
)
type field struct {
children []*field
name string
cnst string
order int
optFlag uint32
nOptFlag uint32
size uint
length uint
flags fieldFlag
strType stringType
version uint8
nVersion uint8
}
func (f *field) set(flag fieldFlag) {
f.flags |= flag
}
func (f *field) is(flag fieldFlag) bool {
return f.flags&flag != 0
}
func buildFields(box IImmutableBox) []*field {
t := reflect.TypeOf(box).Elem()
return buildFieldsStruct(t)
}
func buildFieldsStruct(t reflect.Type) []*field {
fs := make([]*field, 0, 8)
for i := 0; i < t.NumField(); i++ {
ft := t.Field(i).Type
tag, ok := t.Field(i).Tag.Lookup("mp4")
if !ok {
continue
}
f := buildField(t.Field(i).Name, tag)
f.children = buildFieldsAny(ft)
fs = append(fs, f)
}
sort.SliceStable(fs, func(i, j int) bool {
return fs[i].order < fs[j].order
})
return fs
}
func buildFieldsAny(t reflect.Type) []*field {
switch t.Kind() {
case reflect.Struct:
return buildFieldsStruct(t)
case reflect.Ptr, reflect.Array, reflect.Slice:
return buildFieldsAny(t.Elem())
default:
return nil
}
}
func buildField(fieldName string, tag string) *field {
f := &field{
name: fieldName,
}
tagMap := parseFieldTag(tag)
for key, val := range tagMap {
if val != "" {
continue
}
if order, err := strconv.Atoi(key); err == nil {
f.order = order
break
}
}
if val, contained := tagMap["string"]; contained {
f.set(fieldString)
if val == "c_p" {
f.strType = stringType_C_P
fmt.Fprint(os.Stderr, "go-mp4: string=c_p tag is deprecated!! See https://github.com/abema/go-mp4/issues/76\n")
}
}
if _, contained := tagMap["varint"]; contained {
f.set(fieldVarint)
}
if val, contained := tagMap["opt"]; contained {
if val == "dynamic" {
f.set(fieldOptDynamic)
} else {
base := 10
if strings.HasPrefix(val, "0x") {
val = val[2:]
base = 16
}
opt, err := strconv.ParseUint(val, base, 32)
if err != nil {
panic(err)
}
f.optFlag = uint32(opt)
}
}
if val, contained := tagMap["nopt"]; contained {
base := 10
if strings.HasPrefix(val, "0x") {
val = val[2:]
base = 16
}
nopt, err := strconv.ParseUint(val, base, 32)
if err != nil {
panic(err)
}
f.nOptFlag = uint32(nopt)
}
if _, contained := tagMap["extend"]; contained {
f.set(fieldExtend)
}
if _, contained := tagMap["dec"]; contained {
f.set(fieldDec)
}
if _, contained := tagMap["hex"]; contained {
f.set(fieldHex)
}
if _, contained := tagMap["iso639-2"]; contained {
f.set(fieldISO639_2)
}
if _, contained := tagMap["uuid"]; contained {
f.set(fieldUUID)
}
if _, contained := tagMap["hidden"]; contained {
f.set(fieldHidden)
}
if val, contained := tagMap["const"]; contained {
f.cnst = val
}
f.version = anyVersion
if val, contained := tagMap["ver"]; contained {
ver, err := strconv.Atoi(val)
if err != nil {
panic(err)
}
f.version = uint8(ver)
}
f.nVersion = anyVersion
if val, contained := tagMap["nver"]; contained {
ver, err := strconv.Atoi(val)
if err != nil {
panic(err)
}
f.nVersion = uint8(ver)
}
if val, contained := tagMap["size"]; contained {
if val == "dynamic" {
f.set(fieldSizeDynamic)
} else {
size, err := strconv.ParseUint(val, 10, 32)
if err != nil {
panic(err)
}
f.size = uint(size)
}
}
f.length = LengthUnlimited
if val, contained := tagMap["len"]; contained {
if val == "dynamic" {
f.set(fieldLengthDynamic)
} else {
l, err := strconv.ParseUint(val, 10, 32)
if err != nil {
panic(err)
}
f.length = uint(l)
}
}
return f
}
func parseFieldTag(str string) map[string]string {
tag := make(map[string]string, 8)
list := strings.Split(str, ",")
for _, e := range list {
kv := strings.SplitN(e, "=", 2)
if len(kv) == 2 {
tag[strings.Trim(kv[0], " ")] = strings.Trim(kv[1], " ")
} else {
tag[strings.Trim(kv[0], " ")] = ""
}
}
return tag
}
type fieldInstance struct {
field
cfo ICustomFieldObject
}
func resolveFieldInstance(f *field, box IImmutableBox, parent reflect.Value, ctx Context) *fieldInstance {
fi := fieldInstance{
field: *f,
}
cfo, ok := parent.Addr().Interface().(ICustomFieldObject)
if ok {
fi.cfo = cfo
} else {
fi.cfo = box
}
if fi.is(fieldSizeDynamic) {
fi.size = fi.cfo.GetFieldSize(f.name, ctx)
}
if fi.is(fieldLengthDynamic) {
fi.length = fi.cfo.GetFieldLength(f.name, ctx)
}
return &fi
}
func isTargetField(box IImmutableBox, fi *fieldInstance, ctx Context) bool {
if box.GetVersion() != anyVersion {
if fi.version != anyVersion && box.GetVersion() != fi.version {
return false
}
if fi.nVersion != anyVersion && box.GetVersion() == fi.nVersion {
return false
}
}
if fi.optFlag != 0 && box.GetFlags()&fi.optFlag == 0 {
return false
}
if fi.nOptFlag != 0 && box.GetFlags()&fi.nOptFlag != 0 {
return false
}
if fi.is(fieldOptDynamic) && !fi.cfo.IsOptFieldEnabled(fi.name, ctx) {
return false
}
return true
}