cad64fb911
The rules have changed as follows: * When decoding into pointers, empty values no longer produce a nil pointer. This can be overriden for struct fields using the struct tag "nil". * When decoding into structs, the input list must contain an element for each field.
105 lines
2.2 KiB
Go
105 lines
2.2 KiB
Go
package rlp
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import (
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"reflect"
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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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nilOK 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 := parseStructTag(f.Tag.Get("rlp"))
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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(tag string) tags {
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return tags{nilOK: tag == "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); 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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