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|
package rlp
import (
"reflect"
"sync"
)
var (
typeCacheMutex sync.RWMutex
typeCache = make(map[typekey]*typeinfo)
)
type typeinfo struct {
decoder
writer
}
// represents struct tags
type tags struct {
nilOK bool
}
type typekey struct {
reflect.Type
// the key must include the struct tags because they
// might generate a different decoder.
tags
}
type decoder func(*Stream, reflect.Value) error
type writer func(reflect.Value, *encbuf) error
func cachedTypeInfo(typ reflect.Type, tags tags) (*typeinfo, error) {
typeCacheMutex.RLock()
info := typeCache[typekey{typ, tags}]
typeCacheMutex.RUnlock()
if info != nil {
return info, nil
}
// not in the cache, need to generate info for this type.
typeCacheMutex.Lock()
defer typeCacheMutex.Unlock()
return cachedTypeInfo1(typ, tags)
}
func cachedTypeInfo1(typ reflect.Type, tags tags) (*typeinfo, error) {
key := typekey{typ, tags}
info := typeCache[key]
if info != nil {
// another goroutine got the write lock first
return info, nil
}
// put a dummmy value into the cache before generating.
// if the generator tries to lookup itself, it will get
// the dummy value and won't call itself recursively.
typeCache[key] = new(typeinfo)
info, err := genTypeInfo(typ, tags)
if err != nil {
// remove the dummy value if the generator fails
delete(typeCache, key)
return nil, err
}
*typeCache[key] = *info
return typeCache[key], err
}
type field struct {
index int
info *typeinfo
}
func structFields(typ reflect.Type) (fields []field, err error) {
for i := 0; i < typ.NumField(); i++ {
if f := typ.Field(i); f.PkgPath == "" { // exported
tags := parseStructTag(f.Tag.Get("rlp"))
info, err := cachedTypeInfo1(f.Type, tags)
if err != nil {
return nil, err
}
fields = append(fields, field{i, info})
}
}
return fields, nil
}
func parseStructTag(tag string) tags {
return tags{nilOK: tag == "nil"}
}
func genTypeInfo(typ reflect.Type, tags tags) (info *typeinfo, err error) {
info = new(typeinfo)
if info.decoder, err = makeDecoder(typ, tags); err != nil {
return nil, err
}
if info.writer, err = makeWriter(typ); err != nil {
return nil, err
}
return info, nil
}
func isUint(k reflect.Kind) bool {
return k >= reflect.Uint && k <= reflect.Uintptr
}
|
