doc: Refactor man docs

Performance impact (very strange):
benchmark                        old ns/op     new ns/op     delta
BenchmarkGenManToFile-4          30037         29001         -3.45%

benchmark                        old allocs     new allocs     delta
BenchmarkGenManToFile-4          77             89             +15.58%

benchmark                        old bytes     new bytes     delta
BenchmarkGenManToFile-4          9075          9651          +6.35%

doc/man_docs.go

@@ -23,7 +23,7 @@ import (
 	"strings"
 	"time"
 
-	mangen "github.com/cpuguy83/go-md2man/md2man"
+	"github.com/cpuguy83/go-md2man/md2man"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 )
@@ -105,7 +105,7 @@ func GenMan(cmd *cobra.Command, header *GenManHeader, w io.Writer) error {
 	fillHeader(header, cmd.CommandPath())
 
 	b := genMan(cmd, header)
-	_, err := w.Write(mangen.Render(b))
+	_, err := w.Write(md2man.Render(b))
 	return err
 }
 
@@ -126,25 +126,25 @@ func fillHeader(header *GenManHeader, name string) {
 	}
 }
 
-func manPreamble(out io.Writer, header *GenManHeader, cmd *cobra.Command, dashedName string) {
+func manPreamble(buf *bytes.Buffer, header *GenManHeader, cmd *cobra.Command, dashedName string) {
 	description := cmd.Long
 	if len(description) == 0 {
 		description = cmd.Short
 	}
 
-	fmt.Fprintf(out, `%% %s(%s)%s
+	buf.WriteString(fmt.Sprintf(`%% %s(%s)%s
 %% %s
 %% %s
 # NAME
-`, header.Title, header.Section, header.date, header.Source, header.Manual)
+`, header.Title, header.Section, header.date, header.Source, header.Manual))
-	fmt.Fprintf(out, "%s \\- %s\n\n", dashedName, cmd.Short)
+	buf.WriteString(fmt.Sprintf("%s \\- %s\n\n", dashedName, cmd.Short))
-	fmt.Fprintf(out, "# SYNOPSIS\n")
+	buf.WriteString("# SYNOPSIS\n")
-	fmt.Fprintf(out, "**%s**\n\n", cmd.UseLine())
+	buf.WriteString(fmt.Sprintf("**%s**\n\n", cmd.UseLine()))
-	fmt.Fprintf(out, "# DESCRIPTION\n")
+	buf.WriteString("# DESCRIPTION\n")
-	fmt.Fprintf(out, "%s\n\n", description)
+	buf.WriteString(description + "\n\n")
 }
 
-func manPrintFlags(out io.Writer, flags *pflag.FlagSet) {
+func manPrintFlags(buf *bytes.Buffer, flags *pflag.FlagSet) {
 	flags.VisitAll(func(flag *pflag.Flag) {
 		if len(flag.Deprecated) > 0 || flag.Hidden {
 			return
@@ -156,34 +156,34 @@ func manPrintFlags(out io.Writer, flags *pflag.FlagSet) {
 			format = fmt.Sprintf("**--%s**", flag.Name)
 		}
 		if len(flag.NoOptDefVal) > 0 {
-			format = format + "["
+			format += "["
 		}
 		if flag.Value.Type() == "string" {
 			// put quotes on the value
-			format = format + "=%q"
+			format += "=%q"
 		} else {
-			format = format + "=%s"
+			format += "=%s"
 		}
 		if len(flag.NoOptDefVal) > 0 {
-			format = format + "]"
+			format += "]"
 		}
-		format = format + "\n\t%s\n\n"
+		format += "\n\t%s\n\n"
-		fmt.Fprintf(out, format, flag.DefValue, flag.Usage)
+		buf.WriteString(fmt.Sprintf(format, flag.DefValue, flag.Usage))
 	})
 }
 
-func manPrintOptions(out io.Writer, command *cobra.Command) {
+func manPrintOptions(buf *bytes.Buffer, command *cobra.Command) {
 	flags := command.NonInheritedFlags()
 	if flags.HasFlags() {
-		fmt.Fprintf(out, "# OPTIONS\n")
+		buf.WriteString("# OPTIONS\n")
-		manPrintFlags(out, flags)
+		manPrintFlags(buf, flags)
-		fmt.Fprintf(out, "\n")
+		buf.WriteString("\n")
 	}
 	flags = command.InheritedFlags()
 	if flags.HasFlags() {
-		fmt.Fprintf(out, "# OPTIONS INHERITED FROM PARENT COMMANDS\n")
+		buf.WriteString("# OPTIONS INHERITED FROM PARENT COMMANDS\n")
-		manPrintFlags(out, flags)
+		manPrintFlags(buf, flags)
-		fmt.Fprintf(out, "\n")
+		buf.WriteString("\n")
 	}
 }
 
@@ -196,11 +196,11 @@ func genMan(cmd *cobra.Command, header *GenManHeader) []byte {
 	manPreamble(buf, header, cmd, dashCommandName)
 	manPrintOptions(buf, cmd)
 	if len(cmd.Example) > 0 {
-		fmt.Fprintf(buf, "# EXAMPLE\n")
+		buf.WriteString("# EXAMPLE\n")
-		fmt.Fprintf(buf, "```\n%s\n```\n", cmd.Example)
+		buf.WriteString(fmt.Sprintf("```\n%s\n```\n", cmd.Example))
 	}
 	if hasSeeAlso(cmd) {
-		fmt.Fprintf(buf, "# SEE ALSO\n")
+		buf.WriteString("# SEE ALSO\n")
 		seealsos := make([]string, 0)
 		if cmd.HasParent() {
 			parentPath := cmd.Parent().CommandPath()
@@ -222,10 +222,10 @@ func genMan(cmd *cobra.Command, header *GenManHeader) []byte {
 			seealso := fmt.Sprintf("**%s-%s(%s)**", dashCommandName, c.Name(), header.Section)
 			seealsos = append(seealsos, seealso)
 		}
-		fmt.Fprintf(buf, "%s\n", strings.Join(seealsos, ", "))
+		buf.WriteString(strings.Join(seealsos, ", ") + "\n")
 	}
 	if !cmd.DisableAutoGenTag {
-		fmt.Fprintf(buf, "# HISTORY\n%s Auto generated by spf13/cobra\n", header.Date.Format("2-Jan-2006"))
+		buf.WriteString(fmt.Sprintf("# HISTORY\n%s Auto generated by spf13/cobra\n", header.Date.Format("2-Jan-2006")))
 	}
 	return buf.Bytes()
 }

doc/man_docs_test.go

@@ -197,3 +197,20 @@ func AssertNextLineEquals(scanner *bufio.Scanner, expectedLine string) error {
 
 	return fmt.Errorf("AssertNextLineEquals: hit EOF before finding %#v", expectedLine)
 }
+
+func BenchmarkGenManToFile(b *testing.B) {
+	c := initializeWithRootCmd()
+	file, err := ioutil.TempFile("", "")
+	if err != nil {
+		b.Fatal(err)
+	}
+	defer os.Remove(file.Name())
+	defer file.Close()
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		if err := GenMan(c, nil, file); err != nil {
+			b.Fatal(err)
+		}
+	}
+}