New minor release after complete rewrite.

Brings neat and testable codebase with minimum allocations in mind.

utils/ordered_map/ordered_map.go

@@ -0,0 +1,64 @@
+package ordered_map
+
+import (
+	"bytes"
+
+	jsoniter "github.com/json-iterator/go"
+)
+
+var json = jsoniter.ConfigCompatibleWithStandardLibrary
+
+type OrderedMap struct {
+	values map[string]interface{}
+	keys   []string
+}
+
+func New() *OrderedMap {
+	o := OrderedMap{}
+	o.keys = []string{}
+	o.values = map[string]interface{}{}
+	return &o
+}
+
+func (o *OrderedMap) Set(key string, value interface{}) {
+	_, exists := o.values[key]
+	if !exists {
+		o.keys = append(o.keys, key)
+	}
+	o.values[key] = value
+}
+
+func (o OrderedMap) MarshalJSON() ([]byte, error) {
+	var buf bytes.Buffer
+	buf.WriteByte('{')
+	encoder := json.NewEncoder(&buf)
+	encoder.SetEscapeHTML(false)
+	encoder.SetIndent("", "")
+	for i, k := range o.keys {
+		if i > 0 {
+			buf.WriteByte(',')
+		}
+		buf.WriteByte('"')
+		buf.WriteString(k)
+		buf.WriteString(`":`)
+		customEncoder := &customJsonEncoder{buf: &buf}
+		if err := customEncoder.Encode(o.values[k]); err != nil {
+			return nil, err
+		}
+	}
+	buf.WriteByte('}')
+	return buf.Bytes(), nil
+}
+
+type customJsonEncoder struct {
+	buf *bytes.Buffer
+}
+
+func (e *customJsonEncoder) Encode(v interface{}) error {
+	data, err := json.Marshal(v)
+	if err != nil {
+		return err
+	}
+	e.buf.Write(data)
+	return nil
+}