kinda working json unmarshal
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3
internal/ordered/go.mod.txt
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3
internal/ordered/go.mod.txt
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module ordered
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go 1.19
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267
internal/ordered/ordered.go.txt
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267
internal/ordered/ordered.go.txt
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// Package ordered provided a type OrderedMap for use in JSON handling
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// although JSON spec says the keys order of an object should not matter
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// but sometimes when working with particular third-party proprietary code
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// which has incorrect using the keys order, we have to maintain the object keys
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// in the same order of incoming JSON object, this package is useful for these cases.
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//
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// Disclaimer:
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// same as Go's default [map](https://blog.golang.org/go-maps-in-action),
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// this OrderedMap is not safe for concurrent use, if need atomic access, may use a sync.Mutex to synchronize.
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package ordered
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// Refers
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// JSON and Go https://blog.golang.org/json-and-go
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// Go-Ordered-JSON https://github.com/virtuald/go-ordered-json
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// Python OrderedDict https://github.com/python/cpython/blob/2.7/Lib/collections.py#L38
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// port OrderedDict https://github.com/cevaris/ordered_map
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import (
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"bytes"
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"container/list"
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"encoding/json"
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"fmt"
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"io"
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)
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// the key-value pair type, for initializing from a list of key-value pairs, or for looping entries in the same order
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type KVPair struct {
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Key string
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Value interface{}
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}
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type m map[string]interface{}
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// the OrderedMap type, has similar operations as the default map, but maintained
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// the keys order of inserted; similar to map, all single key operations (Get/Set/Delete) runs at O(1).
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type OrderedMap struct {
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m
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l *list.List
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keys map[string]*list.Element // the double linked list for delete and lookup to be O(1)
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}
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// Create a new OrderedMap
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func NewOrderedMap() *OrderedMap {
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return &OrderedMap{
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m: make(map[string]interface{}),
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l: list.New(),
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keys: make(map[string]*list.Element),
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}
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}
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// Create a new OrderedMap and populate from a list of key-value pairs
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func NewOrderedMapFromKVPairs(pairs []*KVPair) *OrderedMap {
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om := NewOrderedMap()
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for _, pair := range pairs {
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om.Set(pair.Key, pair.Value)
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}
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return om
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}
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// return all keys
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// func (om *OrderedMap) Keys() []string { return om.keys }
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// set value for particular key, this will remember the order of keys inserted
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// but if the key already exists, the order is not updated.
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func (om *OrderedMap) Set(key string, value interface{}) {
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if _, ok := om.m[key]; !ok {
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om.keys[key] = om.l.PushBack(key)
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}
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om.m[key] = value
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}
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// Check if value exists
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func (om *OrderedMap) Has(key string) bool {
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_, ok := om.m[key]
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return ok
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}
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// Get value for particular key, or nil if not exist; but don't rely on nil for non-exist; should check by Has or GetValue
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func (om *OrderedMap) Get(key string) interface{} {
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return om.m[key]
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}
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// Get value and exists together
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func (om *OrderedMap) GetValue(key string) (value interface{}, ok bool) {
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value, ok = om.m[key]
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return
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}
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// deletes the element with the specified key (m[key]) from the map. If there is no such element, this is a no-op.
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func (om *OrderedMap) Delete(key string) (value interface{}, ok bool) {
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value, ok = om.m[key]
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if ok {
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om.l.Remove(om.keys[key])
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delete(om.keys, key)
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delete(om.m, key)
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}
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return
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}
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// Iterate all key/value pairs in the same order of object constructed
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func (om *OrderedMap) EntriesIter() func() (*KVPair, bool) {
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e := om.l.Front()
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return func() (*KVPair, bool) {
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if e != nil {
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key := e.Value.(string)
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e = e.Next()
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return &KVPair{key, om.m[key]}, true
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}
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return nil, false
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}
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}
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// Iterate all key/value pairs in the reverse order of object constructed
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func (om *OrderedMap) EntriesReverseIter() func() (*KVPair, bool) {
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e := om.l.Back()
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return func() (*KVPair, bool) {
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if e != nil {
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key := e.Value.(string)
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e = e.Prev()
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return &KVPair{key, om.m[key]}, true
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}
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return nil, false
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}
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}
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// this implements type json.Marshaler interface, so can be called in json.Marshal(om)
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func (om *OrderedMap) MarshalJSON() (res []byte, err error) {
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res = append(res, '{')
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front, back := om.l.Front(), om.l.Back()
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for e := front; e != nil; e = e.Next() {
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k := e.Value.(string)
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res = append(res, fmt.Sprintf("%q:", k)...)
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var b []byte
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b, err = json.Marshal(om.m[k])
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if err != nil {
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return
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}
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res = append(res, b...)
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if e != back {
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res = append(res, ',')
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}
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}
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res = append(res, '}')
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// fmt.Printf("marshalled: %v: %#v\n", res, res)
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return
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}
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// this implements type json.Unmarshaler interface, so can be called in json.Unmarshal(data, om)
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func (om *OrderedMap) UnmarshalJSON(data []byte) error {
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dec := json.NewDecoder(bytes.NewReader(data))
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dec.UseNumber()
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// must open with a delim token '{'
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t, err := dec.Token()
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if err != nil {
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return err
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}
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if delim, ok := t.(json.Delim); !ok || delim != '{' {
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return fmt.Errorf("expect JSON object open with '{'")
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}
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err = om.parseobject(dec)
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if err != nil {
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return err
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}
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t, err = dec.Token()
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if err != io.EOF {
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return fmt.Errorf("expect end of JSON object but got more token: %T: %v or err: %v", t, t, err)
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}
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return nil
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}
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func (om *OrderedMap) parseobject(dec *json.Decoder) (err error) {
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var t json.Token
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for dec.More() {
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t, err = dec.Token()
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if err != nil {
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return err
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}
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key, ok := t.(string)
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if !ok {
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return fmt.Errorf("expecting JSON key should be always a string: %T: %v", t, t)
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}
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t, err = dec.Token()
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if err == io.EOF {
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break
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} else if err != nil {
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return err
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}
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var value interface{}
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value, err = handledelim(t, dec)
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if err != nil {
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return err
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}
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// om.keys = append(om.keys, key)
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om.keys[key] = om.l.PushBack(key)
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om.m[key] = value
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}
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t, err = dec.Token()
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if err != nil {
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return err
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}
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if delim, ok := t.(json.Delim); !ok || delim != '}' {
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return fmt.Errorf("expect JSON object close with '}'")
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}
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return nil
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}
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func parsearray(dec *json.Decoder) (arr []interface{}, err error) {
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var t json.Token
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arr = make([]interface{}, 0)
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for dec.More() {
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t, err = dec.Token()
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if err != nil {
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return
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}
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var value interface{}
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value, err = handledelim(t, dec)
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if err != nil {
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return
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}
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arr = append(arr, value)
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}
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t, err = dec.Token()
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if err != nil {
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return
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}
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if delim, ok := t.(json.Delim); !ok || delim != ']' {
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err = fmt.Errorf("expect JSON array close with ']'")
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return
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}
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return
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}
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func handledelim(t json.Token, dec *json.Decoder) (res interface{}, err error) {
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if delim, ok := t.(json.Delim); ok {
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switch delim {
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case '{':
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om2 := NewOrderedMap()
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err = om2.parseobject(dec)
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if err != nil {
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return
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}
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return om2, nil
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case '[':
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var value []interface{}
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value, err = parsearray(dec)
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if err != nil {
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return
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}
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return value, nil
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default:
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return nil, fmt.Errorf("Unexpected delimiter: %q", delim)
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}
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}
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return t, nil
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}
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