151 lines
3.9 KiB
Go
151 lines
3.9 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package rlp
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import (
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"fmt"
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"reflect"
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"strings"
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"sync"
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)
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var (
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typeCacheMutex sync.RWMutex
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typeCache = make(map[typekey]*typeinfo)
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)
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type typeinfo struct {
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decoder
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writer
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}
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// represents struct tags
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type tags struct {
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// rlp:"nil" controls whether empty input results in a nil pointer.
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nilOK bool
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// rlp:"tail" controls whether this field swallows additional list
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// elements. It can only be set for the last field, which must be
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// of slice type.
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tail bool
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}
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type typekey struct {
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reflect.Type
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// the key must include the struct tags because they
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// might generate a different decoder.
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tags
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}
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type decoder func(*Stream, reflect.Value) error
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type writer func(reflect.Value, *encbuf) error
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func cachedTypeInfo(typ reflect.Type, tags tags) (*typeinfo, error) {
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typeCacheMutex.RLock()
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info := typeCache[typekey{typ, tags}]
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typeCacheMutex.RUnlock()
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if info != nil {
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return info, nil
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}
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// not in the cache, need to generate info for this type.
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typeCacheMutex.Lock()
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defer typeCacheMutex.Unlock()
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return cachedTypeInfo1(typ, tags)
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}
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func cachedTypeInfo1(typ reflect.Type, tags tags) (*typeinfo, error) {
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key := typekey{typ, tags}
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info := typeCache[key]
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if info != nil {
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// another goroutine got the write lock first
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return info, nil
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}
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// put a dummmy value into the cache before generating.
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// if the generator tries to lookup itself, it will get
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// the dummy value and won't call itself recursively.
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typeCache[key] = new(typeinfo)
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info, err := genTypeInfo(typ, tags)
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if err != nil {
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// remove the dummy value if the generator fails
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delete(typeCache, key)
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return nil, err
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}
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*typeCache[key] = *info
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return typeCache[key], err
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}
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type field struct {
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index int
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info *typeinfo
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}
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func structFields(typ reflect.Type) (fields []field, err error) {
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for i := 0; i < typ.NumField(); i++ {
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if f := typ.Field(i); f.PkgPath == "" { // exported
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tags, err := parseStructTag(typ, i)
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if err != nil {
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return nil, err
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}
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info, err := cachedTypeInfo1(f.Type, tags)
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if err != nil {
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return nil, err
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}
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fields = append(fields, field{i, info})
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}
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}
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return fields, nil
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}
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func parseStructTag(typ reflect.Type, fi int) (tags, error) {
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f := typ.Field(fi)
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var ts tags
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for _, t := range strings.Split(f.Tag.Get("rlp"), ",") {
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switch t = strings.TrimSpace(t); t {
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case "":
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case "nil":
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ts.nilOK = true
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case "tail":
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ts.tail = true
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if fi != typ.NumField()-1 {
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return ts, fmt.Errorf(`rlp: invalid struct tag "tail" for %v.%s (must be on last field)`, typ, f.Name)
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}
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if f.Type.Kind() != reflect.Slice {
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return ts, fmt.Errorf(`rlp: invalid struct tag "tail" for %v.%s (field type is not slice)`, typ, f.Name)
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}
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default:
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return ts, fmt.Errorf("rlp: unknown struct tag %q on %v.%s", t, typ, f.Name)
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}
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}
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return ts, nil
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}
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func genTypeInfo(typ reflect.Type, tags tags) (info *typeinfo, err error) {
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info = new(typeinfo)
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if info.decoder, err = makeDecoder(typ, tags); err != nil {
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return nil, err
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}
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if info.writer, err = makeWriter(typ, tags); err != nil {
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return nil, err
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}
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return info, nil
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}
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func isUint(k reflect.Kind) bool {
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return k >= reflect.Uint && k <= reflect.Uintptr
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}
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