Add support for json.Number

Author: vassilvk

decode_test.go

@@ -784,6 +784,14 @@ var unmarshalTests = []struct {
 		"---\nhello\n...\n}not yaml",
 		"hello",
 	},
+	{
+		"a: 5\n",
+		&struct{ A jsonNumberT }{"5"},
+	},
+	{
+		"a: 5.5\n",
+		&struct{ A jsonNumberT }{"5.5"},
+	},
 
 	// Comment scan exhausting the input buffer (issue #469).
 	{
@@ -947,7 +955,7 @@ var unmarshalErrorTests = []struct {
 	{"%TAG !%79! tag:yaml.org,2002:\n---\nv: !%79!int '1'", "yaml: did not find expected whitespace"},
 	{"a:\n  1:\nb\n  2:", ".*could not find expected ':'"},
 	{"a: 1\nb: 2\nc 2\nd: 3\n", "^yaml: line 3: could not find expected ':'$"},
-	{"#\n-\n{", "yaml: line 3: could not find expected ':'"}, // Issue #665
+	{"#\n-\n{", "yaml: line 3: could not find expected ':'"},   // Issue #665
 	{"0: [:!00 \xef", "yaml: incomplete UTF-8 octet sequence"}, // Issue #666
 	{
 		"a: &a [00,00,00,00,00,00,00,00,00]\n" +
@@ -1482,7 +1490,7 @@ func (s *S) TestMergeNestedStruct(c *C) {
 	// 2) A simple implementation might attempt to handle the key skipping
 	//    directly by iterating over the merging map without recursion, but
 	//    there are more complex cases that require recursion.
-	// 
+	//
 	// Quick summary of the fields:
 	//
 	// - A must come from outer and not overriden
@@ -1498,7 +1506,7 @@ func (s *S) TestMergeNestedStruct(c *C) {
 		A, B, C int
 	}
 	type Outer struct {
-		D, E      int
+		D, E   int
 		Inner  Inner
 		Inline map[string]int `yaml:",inline"`
 	}
@@ -1516,10 +1524,10 @@ func (s *S) TestMergeNestedStruct(c *C) {
 	// Repeat test with a map.
 
 	var testm map[string]interface{}
-	var wantm = map[string]interface {} {
-		"f":     60,
+	var wantm = map[string]interface{}{
+		"f": 60,
 		"inner": map[string]interface{}{
-		    "a": 10,
+			"a": 10,
 		},
 		"d": 40,
 		"e": 50,

encode.go

@@ -28,6 +28,19 @@ import (
 	"unicode/utf8"
 )
 
+// jsonNumber is the interface of the encoding/json.Number datatype.
+// Repeating the interface here avoids a dependency on encoding/json, and also
+// supports other libraries like jsoniter, which use a similar datatype with
+// the same interface. Detecting this interface is useful when dealing with
+// structures containing json.Number, which is a string under the hood. The
+// encoder should prefer the use of Int64(), Float64() and string(), in that
+// order, when encoding this type.
+type jsonNumber interface {
+	Float64() (float64, error)
+	Int64() (int64, error)
+	String() string
+}
+
 type encoder struct {
 	emitter  yaml_emitter_t
 	event    yaml_event_t
@@ -127,6 +140,21 @@ func (e *encoder) marshal(tag string, in reflect.Value) {
 		}
 		e.nodev(in.Addr())
 		return
+	case jsonNumber:
+		integer, err := value.Int64()
+		if err == nil {
+			// In this case the json.Number is a valid int64
+			in = reflect.ValueOf(integer)
+			break
+		}
+		float, err := value.Float64()
+		if err == nil {
+			// In this case the json.Number is a valid float64
+			in = reflect.ValueOf(float)
+			break
+		}
+		// fallback case - no number could be obtained
+		in = reflect.ValueOf(value.String())
 	case time.Time:
 		e.timev(tag, in)
 		return

encode_test.go

@@ -30,6 +30,24 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
+type jsonNumberT string
+
+func (j jsonNumberT) Int64() (int64, error) {
+	val, err := strconv.Atoi(string(j))
+	if err != nil {
+		return 0, err
+	}
+	return int64(val), nil
+}
+
+func (j jsonNumberT) Float64() (float64, error) {
+	return strconv.ParseFloat(string(j), 64)
+}
+
+func (j jsonNumberT) String() string {
+	return string(j)
+}
+
 var marshalIntTest = 123
 
 var marshalTests = []struct {
@@ -407,6 +425,18 @@ var marshalTests = []struct {
 		map[string]string{"a": "你好 #comment"},
 		"a: '你好 #comment'\n",
 	},
+	{
+		map[string]interface{}{"a": jsonNumberT("5")},
+		"a: 5\n",
+	},
+	{
+		map[string]interface{}{"a": jsonNumberT("100.5")},
+		"a: 100.5\n",
+	},
+	{
+		map[string]interface{}{"a": jsonNumberT("bogus")},
+		"a: bogus\n",
+	},
 
 	// Ensure MarshalYAML also gets called on the result of MarshalYAML itself.
 	{