encode: Avoid allocations when formatting integers

1 files changed, 11 insertions, 2 deletions

diff --git a/encode.go b/encode.go
index 2e10134..38a2e93 100644
--- a/encode.go
+++ b/encode.go
@@ -228,7 +228,12 @@ func encode(w *ReEncoder, val reflect.Value, escaper BackslashEscaper, quote boo
 					return err
 				}
 			}
-			if _, err := w.WriteString(strconv.FormatInt(val.Int(), 10)); err != nil {
+			// MaxInt64  =  9223372036854775807
+			// MinInt64  =  -9223372036854775808
+			//              0        1         2
+			//              12345678901234567890
+			var buf [20]byte
+			if _, err := w.Write(strconv.AppendInt(buf[:0], val.Int(), 10)); err != nil {
 				return err
 			}
 			if quote {
@@ -242,7 +247,11 @@ func encode(w *ReEncoder, val reflect.Value, escaper BackslashEscaper, quote boo
 					return err
 				}
 			}
-			if _, err := w.WriteString(strconv.FormatUint(val.Uint(), 10)); err != nil {
+			// MaxUint64 = 18446744073709551615
+			//             0        1         2
+			//             12345678901234567890
+			var buf [20]byte
+			if _, err := w.Write(strconv.AppendUint(buf[:0], val.Uint(), 10)); err != nil {
 				return err
 			}
 			if quote {