feat: support negation within JSON format (#500)

Co-authored-by: Ferdinand Neman <ferdinand.neman@gmail.com>

Author: Hi-Fi

pkg/JsonResource.go

@@ -391,7 +391,6 @@ func buildCompoundOperator(o interface{}, depth int, operator string) (string, b
 			}
 		}
 		if depth > 0 {
-
 			return "(" + strings.Join(ands, operator) + ")", false, nil
 		}
 
@@ -467,7 +466,7 @@ func joinOperator(v interface{}, operator string) (string, error) {
 		}
 		ops := make([]string, len(arr))
 		for i := 0; i < len(arr); i++ {
-			ope, err := parseOperand(arr[i], false)
+			ope, err := parseOperand(arr[i], false, operator == " != ")
 			if err != nil {
 
 				return "", err
@@ -487,12 +486,12 @@ func joinSet(v interface{}, operator string) (string, error) {
 
 			return "", fmt.Errorf("set operand count must be 2")
 		}
-		leftOpe, err := parseOperand(arr[0], true)
+		leftOpe, err := parseOperand(arr[0], true, false)
 		if err != nil {
 
 			return "", err
 		}
-		rightOpe, err := parseOperand(arr[1], true)
+		rightOpe, err := parseOperand(arr[1], true, false)
 		if err != nil {
 
 			return "", err
@@ -504,7 +503,7 @@ func joinSet(v interface{}, operator string) (string, error) {
 	return "", fmt.Errorf("operator has an unexpected type")
 }
 
-func parseOperand(o interface{}, noWrap bool) (string, error) {
+func parseOperand(o interface{}, noWrap bool, negation bool) (string, error) {
 	switch operandType := o.(type) {
 	case string:
 
@@ -532,6 +531,10 @@ func parseOperand(o interface{}, noWrap bool) (string, error) {
 			return expr, nil
 		}
 
+		if negation {
+			return "!(" + expr + ")", nil
+		}
+
 		return "(" + expr + ")", nil
 	default:
 

pkg/JsonResource_test.go

@@ -15,8 +15,9 @@
 package pkg
 
 import (
-	"github.com/stretchr/testify/assert"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 const jsonData = `{
@@ -209,6 +210,33 @@ const expectedBigIntConversion = `rule SpeedUp "When testcar is speeding up we k
 }
 `
 
+const jsonNegation = `[{
+    "name": "SpeedConstant",
+    "desc": "When testcar is not speeding up we keep constant \"speed\".",
+    "salience": 10,
+    "when": {
+        "not": [
+            {
+                "and": [
+                    {"eq": ["TestCar.SpeedUp", true]},
+                    {"not": ["TestCar.Speed", 10]}
+                ]
+            }
+        ]
+    },
+    "then": [
+        {"call": ["Log", {"const": "\"Speed\" constant\n"}]}
+    ]
+}]`
+
+const expecteJsonNegation = `rule SpeedConstant "When testcar is not speeding up we keep constant \"speed\"." salience 10 {
+    when
+        !(TestCar.SpeedUp == true && TestCar.Speed != 10)
+    then
+        Log("\"Speed\" constant\n");
+}
+`
+
 func TestParseJSONRuleset(t *testing.T) {
 	rs, err := ParseJSONRule([]byte(jsonData))
 	assert.NoError(t, err)
@@ -262,3 +290,9 @@ func TestJSONBigIntConversion(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, expectedBigIntConversion, rs)
 }
+
+func TestJsonNegation(t *testing.T) {
+	rs, err := ParseJSONRuleset([]byte(jsonNegation))
+	assert.NoError(t, err)
+	assert.Equal(t, expecteJsonNegation, rs)
+}