wip

examples/data1.yaml

@@ -1,4 +1,8 @@
-- name: bob
+# welcome! # cat
-  age: 23
+# bob
-- name: tim
+---
-  age: 17
+# bob
+
+a: cat # meow
+
+# have a great day

examples/data2.yaml

@@ -1,3 +1,2 @@
-#b1 
+c:
-b: 2
+  d: hamster
-#b2

pkg/yqlib/all_at_once_evaluator.go

@@ -73,12 +73,13 @@ func (e *allAtOnceEvaluator) EvaluateFiles(expression string, filenames []string
 		candidateNode := &CandidateNode{
 			Document:       0,
 			Filename:       "",
-			Node:      &yaml.Node{Kind: yaml.DocumentNode, HeadComment: firstFileLeadingContent, Content: []*yaml.Node{{Tag: "!!null", Kind: yaml.ScalarNode}}},
+			Node:           &yaml.Node{Kind: yaml.DocumentNode, Content: []*yaml.Node{{Tag: "!!null", Kind: yaml.ScalarNode}}},
 			FileIndex:      0,
+			LeadingContent: firstFileLeadingContent,
 		}
 		allDocuments.PushBack(candidateNode)
 	} else {
-		allDocuments.Front().Value.(*CandidateNode).Node.HeadComment = firstFileLeadingContent
+		allDocuments.Front().Value.(*CandidateNode).LeadingContent = firstFileLeadingContent
 	}
 
 	matches, err := e.EvaluateCandidateNodes(expression, allDocuments)

pkg/yqlib/candidate_node.go

@@ -11,6 +11,9 @@ import (
 type CandidateNode struct {
 	Node   *yaml.Node     // the actual node
 	Parent *CandidateNode // parent node
+
+	LeadingContent string
+
 	Path      []interface{} /// the path we took to get to this node
 	Document  uint          // the document index of this node
 	Filename  string

pkg/yqlib/doc/comment-operators.md

@@ -139,6 +139,26 @@ will output
 welcome!
 ```
 
+## 
+Given a sample.yml file of:
+```yaml
+# welcome!
+---
+# bob
+a: cat # meow
+
+# have a great day
+```
+then
+```bash
+yq eval 'headComment' sample.yml
+```
+will output
+```yaml
+welcome!
+bob
+```
+
 ## Get foot comment
 Given a sample.yml file of:
 ```yaml
@@ -147,6 +167,7 @@ Given a sample.yml file of:
 a: cat # meow
 
 # have a great day
+# no really
 ```
 then
 ```bash
@@ -155,5 +176,6 @@ yq eval '. | footComment' sample.yml
 will output
 ```yaml
 have a great day
+no really
 ```
 

pkg/yqlib/operator_comments.go

@@ -1,8 +1,12 @@
 package yqlib
 
 import (
+	// "bufio"
+	// "bytes"
+	"bufio"
+	"bytes"
 	"container/list"
-	"strings"
+	"regexp"
 
 	yaml "gopkg.in/yaml.v3"
 )
@@ -57,6 +61,7 @@ func assignCommentsOperator(d *dataTreeNavigator, context Context, expressionNod
 		}
 		if preferences.HeadComment {
 			candidate.Node.HeadComment = comment
+			candidate.LeadingContent = "" // clobber the leading content, if there was any.
 		}
 		if preferences.FootComment {
 			candidate.Node.FootComment = comment
@@ -68,6 +73,9 @@ func assignCommentsOperator(d *dataTreeNavigator, context Context, expressionNod
 
 func getCommentsOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
 	preferences := expressionNode.Operation.Preferences.(commentOpPreferences)
+	var startCommentCharaterRegExp = regexp.MustCompile(`^# `)
+	var subsequentCommentCharaterRegExp = regexp.MustCompile(`\n# `)
+
 	log.Debugf("GetComments operator!")
 	var results = list.New()
 
@@ -76,12 +84,25 @@ func getCommentsOperator(d *dataTreeNavigator, context Context, expressionNode *
 		comment := ""
 		if preferences.LineComment {
 			comment = candidate.Node.LineComment
+		} else if preferences.HeadComment && candidate.LeadingContent != "" {
+			var chompRegexp = regexp.MustCompile(`\n$`)
+			var output bytes.Buffer
+			var writer = bufio.NewWriter(&output)
+			if err := processLeadingContent(candidate, writer, false, YamlOutputFormat); err != nil {
+				return Context{}, err
+			}
+			if err := writer.Flush(); err != nil {
+				return Context{}, err
+			}
+			comment = output.String()
+			comment = chompRegexp.ReplaceAllString(comment, "")
 		} else if preferences.HeadComment {
 			comment = candidate.Node.HeadComment
 		} else if preferences.FootComment {
 			comment = candidate.Node.FootComment
 		}
-		comment = strings.Replace(comment, "# ", "", 1)
+		comment = startCommentCharaterRegExp.ReplaceAllString(comment, "")
+		comment = subsequentCommentCharaterRegExp.ReplaceAllString(comment, "\n")
 
 		node := &yaml.Node{Kind: yaml.ScalarNode, Value: comment, Tag: "!!str"}
 		result := candidate.CreateChild(nil, node)

pkg/yqlib/operator_comments_test.go

@@ -112,13 +112,22 @@ var commentOperatorScenarios = []expressionScenario{
 			"D0, P[], (!!str)::welcome!\n",
 		},
 	},
+	{
+		skipDoc:               false,
+		dontFormatInputForDoc: true,
+		document:              "# welcome!\n---\n# bob\na: cat # meow\n\n# have a great day",
+		expression:            `headComment`,
+		expected: []string{
+			"D0, P[], (!!str)::|-\n    welcome!\n    bob\n",
+		},
+	},
 	{
 		description:           "Get foot comment",
 		dontFormatInputForDoc: true,
-		document:              "# welcome!\n\na: cat # meow\n\n# have a great day",
+		document:              "# welcome!\n\na: cat # meow\n\n# have a great day\n# no really",
 		expression:            `. | footComment`,
 		expected: []string{
-			"D0, P[], (!!str)::have a great day\n",
+			"D0, P[], (!!str)::have a great day\nno really\n",
 		},
 	},
 }

pkg/yqlib/operators_test.go

@@ -26,6 +26,20 @@ type expressionScenario struct {
 	dontFormatInputForDoc bool // dont format input doc for documentation generation
 }
 
+func readDocumentWithLeadingContent(content string, fakefilename string, fakeFileIndex int) (*list.List, error) {
+	reader, firstFileLeadingContent, err := processReadStream(bufio.NewReader(strings.NewReader(content)))
+	if err != nil {
+		return nil, err
+	}
+
+	inputs, err := readDocuments(reader, fakefilename, fakeFileIndex)
+	if err != nil {
+		return nil, err
+	}
+	inputs.Front().Value.(*CandidateNode).LeadingContent = firstFileLeadingContent
+	return inputs, nil
+}
+
 func testScenario(t *testing.T, s *expressionScenario) {
 	var err error
 
@@ -37,15 +51,17 @@ func testScenario(t *testing.T, s *expressionScenario) {
 	inputs := list.New()
 
 	if s.document != "" {
-		inputs, err = readDocuments(strings.NewReader(s.document), "sample.yml", 0)
+		inputs, err = readDocumentWithLeadingContent(s.document, "sample.yml", 0)
+
 		if err != nil {
 			t.Error(err, s.document, s.expression)
 			return
 		}
+
 		if s.document2 != "" {
-			moreInputs, err := readDocuments(strings.NewReader(s.document2), "another.yml", 1)
+			moreInputs, err := readDocumentWithLeadingContent(s.document2, "another.yml", 1)
 			if err != nil {
-				t.Error(err, s.document, s.expression)
+				t.Error(err, s.document2, s.expression)
 				return
 			}
 			inputs.PushBackList(moreInputs)
@@ -227,13 +243,14 @@ func documentOutput(t *testing.T, w *bufio.Writer, s expressionScenario, formatt
 	inputs := list.New()
 
 	if s.document != "" {
-		inputs, err = readDocuments(strings.NewReader(formattedDoc), "sample.yml", 0)
+
+		inputs, err = readDocumentWithLeadingContent(formattedDoc, "sample.yml", 0)
 		if err != nil {
 			t.Error(err, s.document, s.expression)
 			return
 		}
 		if s.document2 != "" {
-			moreInputs, err := readDocuments(strings.NewReader(formattedDoc2), "another.yml", 1)
+			moreInputs, err := readDocumentWithLeadingContent(formattedDoc2, "another.yml", 1)
 			if err != nil {
 				t.Error(err, s.document, s.expression)
 				return

pkg/yqlib/printer.go

@@ -84,7 +84,7 @@ func (p *resultsPrinter) printNode(node *yaml.Node, writer io.Writer) error {
 
 	var encoder Encoder
 	if node.Kind == yaml.ScalarNode && p.unwrapScalar && p.outputFormat == YamlOutputFormat {
-		return p.writeString(writer, node.Value+"\n")
+		return writeString(writer, node.Value+"\n")
 	}
 
 	if p.outputFormat == JsonOutputFormat {
@@ -97,54 +97,6 @@ func (p *resultsPrinter) printNode(node *yaml.Node, writer io.Writer) error {
 	return encoder.Encode(node)
 }
 
-func (p *resultsPrinter) writeString(writer io.Writer, txt string) error {
-	_, errorWriting := writer.Write([]byte(txt))
-	return errorWriting
-}
-
-func (p *resultsPrinter) processLeadingContent(mappedDoc *CandidateNode, writer io.Writer) error {
-	if strings.Contains(mappedDoc.Node.HeadComment, "$yqLeadingContent$") {
-		log.Debug("headcommentwas %v", mappedDoc.Node.HeadComment)
-		log.Debug("finished headcomment")
-		reader := bufio.NewReader(strings.NewReader(mappedDoc.Node.HeadComment))
-		mappedDoc.Node.HeadComment = ""
-
-		for {
-
-			readline, errReading := reader.ReadString('\n')
-			if errReading != nil && errReading != io.EOF {
-				return errReading
-			}
-			if strings.Contains(readline, "$yqLeadingContent$") {
-				// skip this
-
-			} else if strings.Contains(readline, "$yqDocSeperator$") {
-				if p.printDocSeparators {
-					if err := p.writeString(writer, "---\n"); err != nil {
-						return err
-					}
-				}
-			} else if p.outputFormat == YamlOutputFormat {
-				if err := p.writeString(writer, readline); err != nil {
-					return err
-				}
-			}
-
-			if errReading == io.EOF {
-				if readline != "" {
-					// the last comment we read didn't have a new line, put one in
-					if err := p.writeString(writer, "\n"); err != nil {
-						return err
-					}
-				}
-				break
-			}
-		}
-
-	}
-	return nil
-}
-
 func (p *resultsPrinter) PrintResults(matchingNodes *list.List) error {
 	log.Debug("PrintResults for %v matches", matchingNodes.Len())
 
@@ -180,16 +132,16 @@ func (p *resultsPrinter) PrintResults(matchingNodes *list.List) error {
 			return errorWriting
 		}
 
-		commentStartsWithSeparator := strings.Contains(mappedDoc.Node.HeadComment, "$yqLeadingContent$\n$yqDocSeperator$")
+		commentStartsWithSeparator := strings.Contains(mappedDoc.LeadingContent, "$yqLeadingContent$\n$yqDocSeperator$")
 
 		if (p.previousDocIndex != mappedDoc.Document || p.previousFileIndex != mappedDoc.FileIndex) && p.printDocSeparators && !commentStartsWithSeparator {
 			log.Debug("-- writing doc sep")
-			if err := p.writeString(writer, "---\n"); err != nil {
+			if err := writeString(writer, "---\n"); err != nil {
 				return err
 			}
 		}
 
-		if err := p.processLeadingContent(mappedDoc, writer); err != nil {
+		if err := processLeadingContent(mappedDoc, writer, p.printDocSeparators, p.outputFormat); err != nil {
 			return err
 		}
 

pkg/yqlib/stream_evaluator.go

@@ -35,8 +35,9 @@ func (s *streamEvaluator) EvaluateNew(expression string, printer Printer, leadin
 	candidateNode := &CandidateNode{
 		Document:       0,
 		Filename:       "",
-		Node:      &yaml.Node{Kind: yaml.DocumentNode, HeadComment: leadingContent, Content: []*yaml.Node{{Tag: "!!null", Kind: yaml.ScalarNode}}},
+		Node:           &yaml.Node{Kind: yaml.DocumentNode, Content: []*yaml.Node{{Tag: "!!null", Kind: yaml.ScalarNode}}},
 		FileIndex:      0,
+		LeadingContent: leadingContent,
 	}
 	inputList := list.New()
 	inputList.PushBack(candidateNode)
@@ -100,15 +101,16 @@ func (s *streamEvaluator) Evaluate(filename string, reader io.Reader, node *Expr
 		} else if errorReading != nil {
 			return currentIndex, errorReading
 		}
-		if currentIndex == 0 {
+
-			dataBucket.HeadComment = leadingContent
-		}
 		candidateNode := &CandidateNode{
 			Document:  currentIndex,
 			Filename:  filename,
 			Node:      &dataBucket,
 			FileIndex: s.fileIndex,
 		}
+		if currentIndex == 0 {
+			candidateNode.LeadingContent = leadingContent
+		}
 		inputList := list.New()
 		inputList.PushBack(candidateNode)
 

pkg/yqlib/utils.go

@@ -31,6 +31,54 @@ func readStream(filename string, leadingContentPreProcessing bool) (io.Reader, s
 	return processReadStream(reader)
 }
 
+func writeString(writer io.Writer, txt string) error {
+	_, errorWriting := writer.Write([]byte(txt))
+	return errorWriting
+}
+
+func processLeadingContent(mappedDoc *CandidateNode, writer io.Writer, printDocSeparators bool, outputFormat PrinterOutputFormat) error {
+	if strings.Contains(mappedDoc.LeadingContent, "$yqLeadingContent$") {
+		log.Debug("headcommentwas %v", mappedDoc.LeadingContent)
+		log.Debug("finished headcomment")
+		reader := bufio.NewReader(strings.NewReader(mappedDoc.LeadingContent))
+		mappedDoc.Node.HeadComment = ""
+
+		for {
+
+			readline, errReading := reader.ReadString('\n')
+			if errReading != nil && errReading != io.EOF {
+				return errReading
+			}
+			if strings.Contains(readline, "$yqLeadingContent$") {
+				// skip this
+
+			} else if strings.Contains(readline, "$yqDocSeperator$") {
+				if printDocSeparators {
+					if err := writeString(writer, "---\n"); err != nil {
+						return err
+					}
+				}
+			} else if outputFormat == YamlOutputFormat {
+				if err := writeString(writer, readline); err != nil {
+					return err
+				}
+			}
+
+			if errReading == io.EOF {
+				if readline != "" {
+					// the last comment we read didn't have a new line, put one in
+					if err := writeString(writer, "\n"); err != nil {
+						return err
+					}
+				}
+				break
+			}
+		}
+
+	}
+	return nil
+}
+
 func processReadStream(reader *bufio.Reader) (io.Reader, string, error) {
 	var commentLineRegEx = regexp.MustCompile(`^\s*#`)
 	var sb strings.Builder