Improve template mechanisms

* Delete Eq, Gt, appendIfNotPresent and trim functions

* Add "[flags]" in UseLine

* Simplify other functions

* Simplify templates

Minor performance improvement.
Benchmark for command with 4 flags and one child command:
benchmark                   old ns/op     new ns/op     delta
BenchmarkCmdUsageFunc-4     335860        319290        -4.93%

benchmark                   old allocs     new allocs     delta
BenchmarkCmdUsageFunc-4     562            543            -3.38%

benchmark                   old bytes     new bytes     delta
BenchmarkCmdUsageFunc-4     21623         21037         -2.71%

cobra.go

@@ -19,20 +19,14 @@ package cobra
 import (
 	"fmt"
 	"io"
-	"reflect"
-	"strconv"
 	"strings"
 	"text/template"
 	"unicode"
 )
 
 var templateFuncs = template.FuncMap{
-	"trim":               strings.TrimSpace,
-	"trimRightSpace":     trimRightSpace,
-	"appendIfNotPresent": appendIfNotPresent,
+	"trimTrailingWhitespaces": trimTrailingWhitespaces,
 	"rpad": rpad,
-	"gt":                 Gt,
-	"eq":                 Eq,
 }
 
 var initializers []func()
@@ -65,64 +59,10 @@ func OnInitialize(y ...func()) {
 	initializers = append(initializers, y...)
 }
 
-// Gt takes two types and checks whether the first type is greater than the second. In case of types Arrays, Chans,
-// Maps and Slices, Gt will compare their lengths. Ints are compared directly while strings are first parsed as
-// ints and then compared.
-func Gt(a interface{}, b interface{}) bool {
-	var left, right int64
-	av := reflect.ValueOf(a)
-
-	switch av.Kind() {
-	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice:
-		left = int64(av.Len())
-	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		left = av.Int()
-	case reflect.String:
-		left, _ = strconv.ParseInt(av.String(), 10, 64)
-	}
-
-	bv := reflect.ValueOf(b)
-
-	switch bv.Kind() {
-	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice:
-		right = int64(bv.Len())
-	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		right = bv.Int()
-	case reflect.String:
-		right, _ = strconv.ParseInt(bv.String(), 10, 64)
-	}
-
-	return left > right
-}
-
-// Eq takes two types and checks whether they are equal. Supported types are int and string. Unsupported types will panic.
-func Eq(a interface{}, b interface{}) bool {
-	av := reflect.ValueOf(a)
-	bv := reflect.ValueOf(b)
-
-	switch av.Kind() {
-	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice:
-		panic("Eq called on unsupported type")
-	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		return av.Int() == bv.Int()
-	case reflect.String:
-		return av.String() == bv.String()
-	}
-	return false
-}
-
-func trimRightSpace(s string) string {
+func trimTrailingWhitespaces(s string) string {
 	return strings.TrimRightFunc(s, unicode.IsSpace)
 }
 
-// appendIfNotPresent will append stringToAppend to the end of s, but only if it's not yet present in s.
-func appendIfNotPresent(s, stringToAppend string) string {
-	if strings.Contains(s, stringToAppend) {
-		return s
-	}
-	return s + " " + stringToAppend
-}
-
 // rpad adds padding to the right of a string.
 func rpad(s string, padding int) string {
 	template := fmt.Sprintf("%%-%ds", padding)
@@ -131,10 +71,8 @@ func rpad(s string, padding int) string {
 
 // tmpl executes the given template text on data, writing the result to w.
 func tmpl(w io.Writer, text string, data interface{}) error {
-	t := template.New("top")
-	t.Funcs(templateFuncs)
-	template.Must(t.Parse(text))
-	return t.Execute(w, data)
+	t := template.New("top").Funcs(templateFuncs)
+	return template.Must(t.Parse(text)).Execute(w, data)
 }
 
 // ld compares two strings and returns the levenshtein distance between them.

command.go

@@ -330,8 +330,8 @@ func (c *Command) UsageTemplate() string {
 		return c.parent.UsageTemplate()
 	}
 	return `Usage:{{if .Runnable}}
-  {{if .HasAvailableFlags}}{{appendIfNotPresent .UseLine "[flags]"}}{{else}}{{.UseLine}}{{end}}{{end}}{{if .HasAvailableSubCommands}}
-  {{ .CommandPath}} [command]{{end}}{{if gt .Aliases 0}}
+  {{.UseLine}}{{end}}{{if .HasAvailableSubCommands}}
+  {{.CommandPath}} [command]{{end}}{{if gt (len .Aliases) 0}}
 
 Aliases:
   {{.NameAndAliases}}{{end}}{{if .HasExample}}
@@ -343,10 +343,10 @@ Available Commands:{{range .Commands}}{{if (or .IsAvailableCommand (eq .Name "he
   {{rpad .Name .NamePadding }} {{.Short}}{{end}}{{end}}{{end}}{{if .HasAvailableLocalFlags}}
 
 Flags:
-{{.LocalFlags.FlagUsages | trimRightSpace}}{{end}}{{if .HasAvailableInheritedFlags}}
+{{.LocalFlags.FlagUsages | trimTrailingWhitespaces}}{{end}}{{if .HasAvailableInheritedFlags}}
 
 Global Flags:
-{{.InheritedFlags.FlagUsages | trimRightSpace}}{{end}}{{if .HasHelpSubCommands}}
+{{.InheritedFlags.FlagUsages | trimTrailingWhitespaces}}{{end}}{{if .HasHelpSubCommands}}
 
 Additional help topics:{{range .Commands}}{{if .IsAdditionalHelpTopicCommand}}
   {{rpad .CommandPath .CommandPathPadding}} {{.Short}}{{end}}{{end}}{{end}}{{if .HasAvailableSubCommands}}
@@ -364,7 +364,7 @@ func (c *Command) HelpTemplate() string {
 	if c.HasParent() {
 		return c.parent.HelpTemplate()
 	}
-	return `{{with or .Long .Short }}{{. | trim}}
+	return `{{with (or .Long .Short)}}{{. | trimTrailingWhitespaces}}
 
 {{end}}{{if or .Runnable .HasSubCommands}}{{.UsageString}}{{end}}`
 }
@@ -863,34 +863,34 @@ func (c *Command) Print(i ...interface{}) {
 
 // Println is a convenience method to Println to the defined output, fallback to Stderr if not set.
 func (c *Command) Println(i ...interface{}) {
-	str := fmt.Sprintln(i...)
-	c.Print(str)
+	c.Print(fmt.Sprintln(i...))
 }
 
 // Printf is a convenience method to Printf to the defined output, fallback to Stderr if not set.
 func (c *Command) Printf(format string, i ...interface{}) {
-	str := fmt.Sprintf(format, i...)
-	c.Print(str)
+	c.Print(fmt.Sprintf(format, i...))
 }
 
 // CommandPath returns the full path to this command.
 func (c *Command) CommandPath() string {
-	str := c.Name()
-	x := c
-	for x.HasParent() {
-		str = x.parent.Name() + " " + str
-		x = x.parent
+	if c.HasParent() {
+		return c.Parent().CommandPath() + " " + c.Name()
 	}
-	return str
+	return c.Name()
 }
 
 // UseLine puts out the full usage for a given command (including parents).
 func (c *Command) UseLine() string {
-	str := ""
+	var useline string
 	if c.HasParent() {
-		str = c.parent.CommandPath() + " "
+		useline = c.parent.CommandPath() + " " + c.Use
+	} else {
+		useline = c.Use
 	}
-	return str + c.Use
+	if c.HasAvailableFlags() && !strings.Contains(useline, "[flags]") {
+		useline += " [flags]"
+	}
+	return useline
 }
 
 // DebugFlags used to determine which flags have been assigned to which commands
@@ -936,15 +936,14 @@ func (c *Command) DebugFlags() {
 
 // Name returns the command's name: the first word in the use line.
 func (c *Command) Name() string {
-	if c.name != "" {
-		return c.name
-	}
+	if c.name == "" {
 		name := c.Use
 		i := strings.Index(name, " ")
 		if i >= 0 {
 			name = name[:i]
 		}
 		c.name = name
+	}
 	return c.name
 }