Fixing running map against empty array bug #2359

Author: mikefarah

pkg/yqlib/operator_map.go

@@ -41,6 +41,10 @@ func mapOperator(d *dataTreeNavigator, context Context, expressionNode *Expressi
 		if err != nil {
 			return Context{}, err
 		}
+		if splatted.MatchingNodes.Len() == 0 {
+			results.PushBack(candidate.Copy())
+			continue
+		}
 
 		result, err := d.GetMatchingNodes(splatted, expressionNode.RHS)
 		log.Debug("expressionNode.Rhs %v", expressionNode.RHS.Operation.OperationType)

pkg/yqlib/operator_map_test.go

@@ -15,6 +15,46 @@ var mapOperatorScenarios = []expressionScenario{
 			"D0, P[], (!!seq)::[6, 7, 8]\n",
 		},
 	},
+	{
+		description: "mapping against an empty array should do nothing",
+		skipDoc:     true,
+		document:    `[]`,
+		document2:   `["cat"]`,
+		expression:  `map(3)`,
+		expected: []string{
+			"D0, P[], (!!seq)::[]\n",
+			"D0, P[], (!!seq)::[3]\n",
+		},
+	},
+	{
+		description: "mapping against an empty array should do nothing",
+		skipDoc:     true,
+		document:    `[[], [5]]`,
+		expression:  `.[] |= map(3)`,
+		expected: []string{
+			"D0, P[], (!!seq)::[[], [3]]\n",
+		},
+	},
+	{
+		description: "mapping against an empty array should do nothing #2",
+		skipDoc:     true,
+		document:    `[]`,
+		document2:   `[5]`,
+		expression:  `map(3 + .)`,
+		expected: []string{
+			"D0, P[], (!!seq)::[]\n",
+			"D0, P[], (!!seq)::[8]\n",
+		},
+	},
+	{
+		description: "mapping against an empty array should do nothing",
+		skipDoc:     true,
+		document:    `[[], [5]]`,
+		expression:  `.[] |= map(3 + .)`,
+		expected: []string{
+			"D0, P[], (!!seq)::[[], [8]]\n",
+		},
+	},
 	{
 		skipDoc:    true,
 		expression: `[] | map(. + 42)`,
@@ -39,6 +79,26 @@ var mapOperatorScenarios = []expressionScenario{
 			"D0, P[], (!!seq)::[2, 3, 4]\n",
 		},
 	},
+	{
+		skipDoc:    true,
+		document:   `{}`,
+		document2:  `{b: 12}`,
+		expression: `map_values(3)`,
+		expected: []string{
+			"D0, P[], (!!map)::{}\n",
+			"D0, P[], (!!map)::{b: 3}\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   `{}`,
+		document2:  `{b: 12}`,
+		expression: `map_values(3 + .)`,
+		expected: []string{
+			"D0, P[], (!!map)::{}\n",
+			"D0, P[], (!!map)::{b: 15}\n",
+		},
+	},
 	{
 		skipDoc:    true,
 		document:   `{a: 1, b: 2, c: 3}`,