Fixed for most cases, except strip comments

pkg/yqlib/all_at_once_evaluator.go

@@ -8,7 +8,7 @@ import (
 
 // A yaml expression evaluator that runs the expression once against all files/nodes in memory.
 type Evaluator interface {
-	EvaluateFiles(expression string, filenames []string, printer Printer) error
+	EvaluateFiles(expression string, filenames []string, printer Printer, leadingContentPreProcessing bool) error
 
 	// EvaluateNodes takes an expression and one or more yaml nodes, returning a list of matching candidate nodes
 	EvaluateNodes(expression string, nodes ...*yaml.Node) (*list.List, error)
@@ -46,13 +46,13 @@ func (e *allAtOnceEvaluator) EvaluateCandidateNodes(expression string, inputCand
 	return context.MatchingNodes, nil
 }
 
-func (e *allAtOnceEvaluator) EvaluateFiles(expression string, filenames []string, printer Printer) error {
+func (e *allAtOnceEvaluator) EvaluateFiles(expression string, filenames []string, printer Printer, leadingContentPreProcessing bool) error {
 	fileIndex := 0
 	firstFileLeadingContent := ""
 
 	var allDocuments *list.List = list.New()
 	for _, filename := range filenames {
-		reader, leadingContent, err := readStream(filename)
+		reader, leadingContent, err := readStream(filename, leadingContentPreProcessing)
 		if err != nil {
 			return err
 		}

pkg/yqlib/printer.go

@@ -128,9 +128,14 @@ func (p *resultsPrinter) PrintResults(matchingNodes *list.List, leadingContent s
 		}
 
 		if !printedLead {
-			// we want to print this after the seperator logic
-			if err := p.writeString(bufferedWriter, leadingContent); err != nil {
-				return err
+			// dont print leading comments and seperator if:
+			// - we are print json; or
+			// - we are printing an unwrapped scalar node
+			if !p.outputToJSON && (mappedDoc.Node.Kind != yaml.ScalarNode || !p.unwrapScalar) {
+				// we want to print this after the seperator logic
+				if err := p.writeString(bufferedWriter, leadingContent); err != nil {
+					return err
+				}
 			}
 			printedLead = true
 		}

pkg/yqlib/printer_test.go

@@ -276,6 +276,31 @@ a: coconut
 	test.AssertResult(t, expected, output.String())
 }
 
+func TestPrinterScalarWithLeadingCont(t *testing.T) {
+	var output bytes.Buffer
+	var writer = bufio.NewWriter(&output)
+	printer := NewPrinter(writer, false, true, false, 2, true)
+
+	node, err := NewExpressionParser().ParseExpression(".a")
+	if err != nil {
+		panic(err)
+	}
+	streamEvaluator := NewStreamEvaluator()
+	_, err = streamEvaluator.Evaluate("sample", strings.NewReader(multiDocSample), node, printer, "# blah\n")
+	if err != nil {
+		panic(err)
+	}
+
+	writer.Flush()
+	expected := `banana
+---
+apple
+---
+coconut
+`
+	test.AssertResult(t, expected, output.String())
+}
+
 func TestPrinterMultipleDocsJson(t *testing.T) {
 	var output bytes.Buffer
 	var writer = bufio.NewWriter(&output)
@@ -288,7 +313,7 @@ func TestPrinterMultipleDocsJson(t *testing.T) {
 		panic(err)
 	}
 
-	err = printer.PrintResults(inputs, "")
+	err = printer.PrintResults(inputs, "# ignore this")
 	if err != nil {
 		panic(err)
 	}

pkg/yqlib/stream_evaluator.go

@@ -13,7 +13,7 @@ import (
 // cross document expressions.
 type StreamEvaluator interface {
 	Evaluate(filename string, reader io.Reader, node *ExpressionNode, printer Printer, leadingContent string) (uint, error)
-	EvaluateFiles(expression string, filenames []string, printer Printer) error
+	EvaluateFiles(expression string, filenames []string, printer Printer, leadingContentPreProcessing bool) error
 	EvaluateNew(expression string, printer Printer, leadingContent string) error
 }
 
@@ -48,7 +48,7 @@ func (s *streamEvaluator) EvaluateNew(expression string, printer Printer, leadin
 	return printer.PrintResults(result.MatchingNodes, leadingContent)
 }
 
-func (s *streamEvaluator) EvaluateFiles(expression string, filenames []string, printer Printer) error {
+func (s *streamEvaluator) EvaluateFiles(expression string, filenames []string, printer Printer, leadingContentPreProcessing bool) error {
 	var totalProcessDocs uint = 0
 	node, err := s.treeCreator.ParseExpression(expression)
 	if err != nil {
@@ -58,7 +58,7 @@ func (s *streamEvaluator) EvaluateFiles(expression string, filenames []string, p
 	var firstFileLeadingContent string
 
 	for index, filename := range filenames {
-		reader, leadingContent, err := readStream(filename)
+		reader, leadingContent, err := readStream(filename, leadingContentPreProcessing)
 
 		if index == 0 {
 			firstFileLeadingContent = leadingContent

pkg/yqlib/utils.go

@@ -11,7 +11,7 @@ import (
 	yaml "gopkg.in/yaml.v3"
 )
 
-func readStream(filename string) (io.Reader, string, error) {
+func readStream(filename string, leadingContentPreProcessing bool) (io.Reader, string, error) {
 	var commentLineRegEx = regexp.MustCompile(`^\s*#`)
 	var reader *bufio.Reader
 	if filename == "-" {
@@ -27,6 +27,10 @@ func readStream(filename string) (io.Reader, string, error) {
 	}
 	var sb strings.Builder
 
+	if !leadingContentPreProcessing {
+		return reader, "", nil
+	}
+
 	for {
 		peekBytes, err := reader.Peek(3)