Fixing comments in TOML arrays #2592 (#2595)

pkg/yqlib/decoder_toml.go

@@ -157,13 +157,30 @@ func (dec *tomlDecoder) createInlineTableMap(tomlNode *toml.Node) (*CandidateNod
 
 func (dec *tomlDecoder) createArray(tomlNode *toml.Node) (*CandidateNode, error) {
 	content := make([]*CandidateNode, 0)
+	var pendingArrayComments []string
+
 	iterator := tomlNode.Children()
 	for iterator.Next() {
 		child := iterator.Node()
+
+		// Handle comments within arrays
+		if child.Kind == toml.Comment {
+			// Collect comments to attach to the next array element
+			pendingArrayComments = append(pendingArrayComments, string(child.Data))
+			continue
+		}
+
 		yamlNode, err := dec.decodeNode(child)
 		if err != nil {
 			return nil, err
 		}
+
+		// Attach any pending comments to this array element
+		if len(pendingArrayComments) > 0 {
+			yamlNode.HeadComment = strings.Join(pendingArrayComments, "\n")
+			pendingArrayComments = make([]string, 0)
+		}
+
 		content = append(content, yamlNode)
 	}
 

pkg/yqlib/encoder_toml.go

@@ -222,6 +222,81 @@ func (te *tomlEncoder) writeArrayAttribute(w io.Writer, key string, seq *Candida
 		return err
 	}
 
+	// Check if any array elements have head comments - if so, use multiline format
+	hasElementComments := false
+	for _, it := range seq.Content {
+		if it.HeadComment != "" {
+			hasElementComments = true
+			break
+		}
+	}
+
+	if hasElementComments {
+		// Write multiline array format with comments
+		if _, err := w.Write([]byte(key + " = [\n")); err != nil {
+			return err
+		}
+
+		for i, it := range seq.Content {
+			// Write head comment for this element
+			if it.HeadComment != "" {
+				commentLines := strings.Split(it.HeadComment, "\n")
+				for _, commentLine := range commentLines {
+					if strings.TrimSpace(commentLine) != "" {
+						if !strings.HasPrefix(strings.TrimSpace(commentLine), "#") {
+							commentLine = "# " + commentLine
+						}
+						if _, err := w.Write([]byte("  " + commentLine + "\n")); err != nil {
+							return err
+						}
+					}
+				}
+			}
+
+			// Write the element value
+			var itemStr string
+			switch it.Kind {
+			case ScalarNode:
+				itemStr = te.formatScalar(it)
+			case SequenceNode:
+				nested, err := te.sequenceToInlineArray(it)
+				if err != nil {
+					return err
+				}
+				itemStr = nested
+			case MappingNode:
+				inline, err := te.mappingToInlineTable(it)
+				if err != nil {
+					return err
+				}
+				itemStr = inline
+			case AliasNode:
+				return fmt.Errorf("aliases are not supported in TOML")
+			default:
+				return fmt.Errorf("unsupported array item kind: %v", it.Kind)
+			}
+
+			// Always add trailing comma in multiline arrays
+			itemStr += ","
+
+			if _, err := w.Write([]byte("  " + itemStr + "\n")); err != nil {
+				return err
+			}
+
+			// Add blank line between elements (except after the last one)
+			if i < len(seq.Content)-1 {
+				if _, err := w.Write([]byte("\n")); err != nil {
+					return err
+				}
+			}
+		}
+
+		if _, err := w.Write([]byte("]\n")); err != nil {
+			return err
+		}
+		return nil
+	}
+
 	// Join scalars or nested arrays recursively into TOML array syntax
 	items := make([]string, 0, len(seq.Content))
 	for _, it := range seq.Content {

pkg/yqlib/toml_test.go

@@ -271,6 +271,16 @@ var subArrays = `
 [[array.subarray.subsubarray]]
 `
 
+var tomlTableWithComments = `[section]
+the_array = [
+  # comment
+  "value 1",
+
+  # comment
+  "value 2",
+]
+`
+
 var expectedSubArrays = `array:
   - subarray:
       - subsubarray:
@@ -598,6 +608,12 @@ var tomlScenarios = []formatScenario{
 		expected:     sampleFromWeb,
 		scenarioType: "roundtrip",
 	},
+	{
+		skipDoc:      true,
+		input:        tomlTableWithComments,
+		expected:     tomlTableWithComments,
+		scenarioType: "roundtrip",
+	},
 }
 
 func testTomlScenario(t *testing.T, s formatScenario) {