lsf: Add --csv flag for compliant CSV output

fs/operations/operations.go

@@ -4,6 +4,7 @@ package operations
 import (
 	"bytes"
 	"context"
+	"encoding/csv"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -1368,6 +1369,8 @@ type ListFormat struct {
 	dirSlash  bool
 	output    []func() string
 	entry     fs.DirEntry
+	csv       *csv.Writer
+	buf       bytes.Buffer
 }
 
 // SetSeparator changes separator in struct
@@ -1380,6 +1383,21 @@ func (l *ListFormat) SetDirSlash(dirSlash bool) {
 	l.dirSlash = dirSlash
 }
 
+// SetCSV defines if the output should be csv
+//
+// Note that you should call SetSeparator before this if you want a
+// custom separator
+func (l *ListFormat) SetCSV(useCSV bool) {
+	if useCSV {
+		l.csv = csv.NewWriter(&l.buf)
+		if l.separator != "" {
+			l.csv.Comma = []rune(l.separator)[0]
+		}
+	} else {
+		l.csv = nil
+	}
+}
+
 // SetOutput sets functions used to create files information
 func (l *ListFormat) SetOutput(output []func() string) {
 	l.output = output
@@ -1439,18 +1457,23 @@ func (l *ListFormat) AddMimeType() {
 
 // AppendOutput adds string generated by specific function to printed output
 func (l *ListFormat) AppendOutput(functionToAppend func() string) {
-	if len(l.output) > 0 {
-		l.output = append(l.output, func() string { return l.separator })
-	}
 	l.output = append(l.output, functionToAppend)
 }
 
 // Format prints information about the DirEntry in the format defined
-func (l *ListFormat) Format(entry fs.DirEntry) string {
+func (l *ListFormat) Format(entry fs.DirEntry) (result string) {
 	l.entry = entry
-	var out string
+	var out []string
 	for _, fun := range l.output {
-		out += fun()
+		out = append(out, fun())
 	}
-	return out
+	if l.csv != nil {
+		l.buf.Reset()
+		_ = l.csv.Write(out) // can't fail writing to bytes.Buffer
+		l.csv.Flush()
+		result = strings.TrimRight(l.buf.String(), "\n")
+	} else {
+		result = strings.Join(out, l.separator)
+	}
+	return result
 }