feat(dec.raw): introduce Raw type

dec.go

@@ -6,7 +6,7 @@ import (
 	"github.com/ogen-go/errors"
 )
 
-// Type the type for JSON element
+// Type of json value.
 type Type int
 
 func (t Type) String() string {

dec_raw.go

@@ -4,8 +4,8 @@ import "github.com/ogen-go/errors"
 
 // Raw is like Skip(), but saves and returns skipped value as raw json.
 //
-// Do not retain returned slice, it references underlying buffer.
-func (d *Decoder) Raw() ([]byte, error) {
+// Do not retain returned value, it references underlying buffer.
+func (d *Decoder) Raw() (Raw, error) {
 	if d.reader != nil {
 		return nil, errors.New("not implemented for io.Reader")
 	}
@@ -19,10 +19,19 @@ func (d *Decoder) Raw() ([]byte, error) {
 }
 
 // RawAppend is Raw that appends saved raw json value to buf.
-func (d *Decoder) RawAppend(buf []byte) ([]byte, error) {
+func (d *Decoder) RawAppend(buf Raw) (Raw, error) {
 	raw, err := d.Raw()
 	if err != nil {
 		return nil, err
 	}
 	return append(buf, raw...), err
 }
+
+// Raw json value.
+type Raw []byte
+
+// Type of Raw json value.
+func (r Raw) Type() Type {
+	d := Decoder{buf: r, tail: len(r)}
+	return d.Next()
+}

dec_raw_test.go

@@ -82,3 +82,14 @@ func BenchmarkDecoder_Raw(b *testing.B) {
 		}
 	}
 }
+
+func BenchmarkRaw_Type(b *testing.B) {
+	v := Raw{'1'}
+
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		if v.Type() != Number {
+			b.Fatal("invalid")
+		}
+	}
+}