Added builtin function to_json

objects/builtin_json.go:
	- Added function builtinToJSON

objects/builtins.go:
	- Added builtin function to_json

runtime/vm_builtin_test.go
	- Added tests for builtin function to_json

objects/builtin_json.go

@@ -0,0 +1,18 @@
+package objects
+
+import (
+	"encoding/json"
+)
+
+func builtinToJSON(args ...Object) (Object, error) {
+	if len(args) != 1 {
+		return nil, ErrWrongNumArguments
+	}
+
+	res, err := json.Marshal(objectToInterface(args[0]))
+	if err != nil {
+		return nil, err
+	}
+
+	return &Bytes{Value: res}, nil
+}

objects/builtins.go

@@ -80,4 +80,8 @@ var Builtins = []NamedBuiltinFunc{
 		Name: "is_undefined",
 		Func: builtinIsUndefined,
 	},
+	{
+		Name: "to_json",
+		Func: builtinToJSON,
+	},
 }

runtime/vm_builtin_test.go

@@ -113,4 +113,19 @@ func TestBuiltinFunction(t *testing.T) {
 
 	expect(t, `out = is_undefined(undefined)`, true)
 	expect(t, `out = is_undefined(error(1))`, false)
+
+	// to_json
+	expect(t, `out = to_json(5)`, []byte("5"))
+	expect(t, `out = to_json({foo: 5})`, []byte("{\"foo\":5}"))
+	expect(t, `out = to_json({foo: "bar"})`, []byte("{\"foo\":\"bar\"}"))
+	expect(t, `out = to_json({foo: 1.8})`, []byte("{\"foo\":1.8}"))
+	expect(t, `out = to_json({foo: true})`, []byte("{\"foo\":true}"))
+	expect(t, `out = to_json({foo: '8'})`, []byte("{\"foo\":56}"))
+	expect(t, `out = to_json({foo: bytes("foo")})`, []byte("{\"foo\":\"Zm9v\"}")) // json encoding returns []byte as base64 encoded string
+	expect(t, `out = to_json({foo: ["bar", 1, 1.8, '8', true]})`, []byte("{\"foo\":[\"bar\",1,1.8,56,true]}"))
+	expect(t, `out = to_json({foo: [["bar", 1], ["bar", 1]]})`, []byte("{\"foo\":[[\"bar\",1],[\"bar\",1]]}"))
+	expect(t, `out = to_json({foo: {string: "bar", int: 1, float: 1.8, char: '8', bool: true}})`, []byte("{\"foo\":{\"bool\":true,\"char\":56,\"float\":1.8,\"int\":1,\"string\":\"bar\"}}"))
+	expect(t, `out = to_json({foo: {map1: {string: "bar"}, map2: {int: "1"}}})`, []byte("{\"foo\":{\"map1\":{\"string\":\"bar\"},\"map2\":{\"int\":\"1\"}}}"))
+	expect(t, `out = to_json([["bar", 1], ["bar", 1]])`, []byte("[[\"bar\",1],[\"bar\",1]]"))
+
 }