optimize fixed size array

Author: Tao Wen

generator/encoder.go

@@ -83,6 +83,13 @@ func encodeAnonymousStruct(structType *ast.StructType) string {
 }
 
 func encodeArray(arrayType *ast.ArrayType) {
+	if arrayType.Len != nil {
+		arrayLen, err := strconv.ParseInt(nodeToString(arrayType.Len), 10, 64)
+		if err == nil && arrayLen < 10 {
+			encodeFixedSizeArray(arrayType, int(arrayLen))
+			return
+		}
+	}
 	_l("  if len(val) == 0 {")
 	_l("    stream.WriteEmptyArray()")
 	_l("  } else {")
@@ -95,6 +102,17 @@ func encodeArray(arrayType *ast.ArrayType) {
 	_l("  }")
 }
 
+func encodeFixedSizeArray(arrayType *ast.ArrayType, length int) {
+	_l("    stream.WriteArrayHead()")
+	for i := 0; i < length; i++ {
+		if i != 0 {
+			_l("    stream.WriteMore()")
+		}
+		genEncodeStmt(arrayType.Elt, fmt.Sprintf("val[%d]", i))
+	}
+	_l("    stream.WriteArrayTail()")
+}
+
 func encodeMap(mapType *ast.MapType) {
 	_l("  if len(val) == 0 {")
 	_l("    stream.WriteEmptyObject()")

value_tests/NestedArray_json.go

@@ -66,14 +66,9 @@ func NestedArray_json_marshal(stream *jsoniter.Stream, val NestedArray) {
   }
 }
 func NestedArray_array2_json_marshal (stream *jsoniter.Stream, val [2]float64) {
-  if len(val) == 0 {
-    stream.WriteEmptyArray()
-  } else {
     stream.WriteArrayHead()
-    for i, elem := range val {
-      if i != 0 { stream.WriteMore() }
-    stream.WriteFloat64(elem)
-    }
+    stream.WriteFloat64(val[0])
+    stream.WriteMore()
+    stream.WriteFloat64(val[1])
     stream.WriteArrayTail()
-  }
 }