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// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package rlp
import (
"fmt"
"reflect"
"strings"
"sync"
)
var (
typeCacheMutex sync.RWMutex
typeCache = make(map[typekey]*typeinfo)
)
type typeinfo struct {
decoder
writer
}
// represents struct tags
type tags struct {
// rlp:"nil" controls whether empty input results in a nil pointer.
nilOK bool
// rlp:"tail" controls whether this field swallows additional list
// elements. It can only be set for the last field, which must be
// of slice type.
tail bool
// rlp:"-" ignores fields.
ignored 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 dummy 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, err := parseStructTag(typ, i)
if err != nil {
return nil, err
}
if tags.ignored {
continue
}
info, err := cachedTypeInfo1(f.Type, tags)
if err != nil {
return nil, err
}
fields = append(fields, field{i, info})
}
}
return fields, nil
}
func parseStructTag(typ reflect.Type, fi int) (tags, error) {
f := typ.Field(fi)
var ts tags
for _, t := range strings.Split(f.Tag.Get("rlp"), ",") {
switch t = strings.TrimSpace(t); t {
case "":
case "-":
ts.ignored = true
case "nil":
ts.nilOK = true
case "tail":
ts.tail = true
if fi != typ.NumField()-1 {
return ts, fmt.Errorf(`rlp: invalid struct tag "tail" for %v.%s (must be on last field)`, typ, f.Name)
}
if f.Type.Kind() != reflect.Slice {
return ts, fmt.Errorf(`rlp: invalid struct tag "tail" for %v.%s (field type is not slice)`, typ, f.Name)
}
default:
return ts, fmt.Errorf("rlp: unknown struct tag %q on %v.%s", t, typ, f.Name)
}
}
return ts, 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, tags); err != nil {
return nil, err
}
return info, nil
}
func isUint(k reflect.Kind) bool {
return k >= reflect.Uint && k <= reflect.Uintptr
}
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