Fixed array subtraction update bug #2159

Author: mikefarah

pkg/yqlib/operator_add_test.go

@@ -14,6 +14,14 @@ var addOperatorScenarios = []expressionScenario{
 			"D0, P[1 a], (!!int)::3\n",
 		},
 	},
+	{
+		skipDoc:     true,
+		description: "add sequence creates a new sequence",
+		expression:  `["a"] as $f | {0:$f + ["b"], 1:$f}`,
+		expected: []string{
+			"D0, P[], (!!map)::0:\n    - a\n    - b\n1:\n    - a\n",
+		},
+	},
 	{
 		skipDoc:    true,
 		document:   `a: key`,

pkg/yqlib/operator_subtract.go

@@ -23,7 +23,7 @@ func subtractOperator(d *dataTreeNavigator, context Context, expressionNode *Exp
 	return crossFunction(d, context.ReadOnlyClone(), expressionNode, subtract, false)
 }
 
-func subtractArray(lhs *CandidateNode, rhs *CandidateNode) (*CandidateNode, error) {
+func subtractArray(lhs *CandidateNode, rhs *CandidateNode) []*CandidateNode {
 	newLHSArray := make([]*CandidateNode, 0)
 
 	for lindex := 0; lindex < len(lhs.Content); lindex = lindex + 1 {
@@ -37,9 +37,7 @@ func subtractArray(lhs *CandidateNode, rhs *CandidateNode) (*CandidateNode, erro
 			newLHSArray = append(newLHSArray, lhs.Content[lindex])
 		}
 	}
-	// removing children from LHS, parent hasn't changed
-	lhs.Content = newLHSArray
-	return lhs, nil
+	return newLHSArray
 }
 
 func subtract(_ *dataTreeNavigator, context Context, lhs *CandidateNode, rhs *CandidateNode) (*CandidateNode, error) {
@@ -56,7 +54,7 @@ func subtract(_ *dataTreeNavigator, context Context, lhs *CandidateNode, rhs *Ca
 		if rhs.Kind != SequenceNode {
 			return nil, fmt.Errorf("%v (%v) cannot be subtracted from %v", rhs.Tag, rhs.GetNicePath(), lhs.Tag)
 		}
-		return subtractArray(lhs, rhs)
+		target.Content = subtractArray(lhs, rhs)
 	case ScalarNode:
 		if rhs.Kind != ScalarNode {
 			return nil, fmt.Errorf("%v (%v) cannot be subtracted from %v", rhs.Tag, rhs.GetNicePath(), lhs.Tag)

pkg/yqlib/operator_subtract_test.go

@@ -13,6 +13,14 @@ var subtractOperatorScenarios = []expressionScenario{
 			"D0, P[], (!!map)::{}\n",
 		},
 	},
+	{
+		skipDoc:     true,
+		description: "subtract sequence creates a new sequence",
+		expression:  `["a", "b"] as $f | {0:$f - ["a"], 1:$f}`,
+		expected: []string{
+			"D0, P[], (!!map)::0:\n    - b\n1:\n    - a\n    - b\n",
+		},
+	},
 	{
 		description: "Array subtraction",
 		expression:  `[1,2] - [2,3]`,