nix-amer/internal/cnf/json.go

131 lines
2.6 KiB
Go

package cnf
import (
"encoding/json"
"io"
"strings"
)
type Json struct {
data interface{}
parsed bool
}
// Parse extract a reader as its JSON representation
func (d *Json) Parse(_reader io.Reader) error {
// 1. get json decoder
decoder := json.NewDecoder(_reader)
err := decoder.Decode(&d.data)
if err != nil {
return err
}
d.parsed = true
return nil
}
// browse returns the target of a dot-separated path (as an interface{} chain where the last is the target if found)
func (d *Json) browse(_path string) ([]interface{}, bool) {
// 1. extract path
path := strings.Split(_path, ".")
// 2. init output chain
current := d.data
chain := make([]interface{}, 0, len(path)+1)
chain = append(chain, current)
// 3. iterate over path / nested fields
for _, field := range path {
fmap, ok := current.(map[string]interface{})
if !ok { // incomplete path
return chain, false
}
child, ok := fmap[field]
if !ok { // incomplete path
return chain, false
}
current = child
chain = append(chain, current)
}
return chain, true
}
// Get returns the value of a dot-separated path, and if it exists
func (d *Json) Get(_path string) (string, bool) {
// 1. browse path
chain, found := d.browse(_path)
if !found {
return "", false
}
// 2. return if string value
value, ok := chain[len(chain)-1].(string)
return value, ok
}
// Set the value of a dot-separated path, and creates it if not found
func (d *Json) Set(_path, _value string) bool {
// 1. browse path + create it if does not exist
path := strings.Split(_path, ".")
lp := len(path)
chain, found := d.browse(_path)
// 2. if found -> set value
if found {
mapWrapper, ok := chain[len(chain)-2].(map[string]interface{})
if !ok { // impossible
return false
}
key := path[lp-1]
mapWrapper[key] = _value
return true
}
// 3. create path until the end to set value
root := make(map[string]interface{})
current := root
// create children until second to last
for i, l := len(chain)-1, lp-1; i < l; i++ {
child := make(map[string]interface{})
current[path[i]] = child
current = child
}
// set value
current[path[lp-1]] = _value
// replace whole object if empty
if len(chain) < 2 {
wrapper, ok := d.data.(map[string]interface{})
if !ok { // impossible
return false
}
key := path[0]
wrapper[key] = root[key] // store with key ; eitherway it will erase all brother keys
return true
}
// update last found object to add the value
wrapper, ok := chain[len(chain)-1].(map[string]interface{})
if !ok { // impossible
return false
}
// add each subkey
for subkey, subvalue := range root {
wrapper[subkey] = subvalue
}
return true
}