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usage.go
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usage.go
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package kingpin
import (
"bytes"
"fmt"
"go/doc"
"io"
"strings"
"text/template"
)
var (
preIndent = " "
)
func formatTwoColumns(w io.Writer, indent, padding, width int, rows [][2]string) {
// Find size of first column.
s := 0
for _, row := range rows {
if c := len(row[0]); c > s && c < 30 {
s = c
}
}
indentStr := strings.Repeat(" ", indent)
offsetStr := strings.Repeat(" ", s+padding)
for _, row := range rows {
buf := bytes.NewBuffer(nil)
doc.ToText(buf, row[1], "", preIndent, width-s-padding-indent)
lines := strings.Split(strings.TrimRight(buf.String(), "\n"), "\n")
fmt.Fprintf(w, "%s%-*s%*s", indentStr, s, row[0], padding, "")
if len(row[0]) >= 30 {
fmt.Fprintf(w, "\n%s%s", indentStr, offsetStr)
}
fmt.Fprintf(w, "%s\n", lines[0])
for _, line := range lines[1:] {
fmt.Fprintf(w, "%s%s%s\n", indentStr, offsetStr, line)
}
}
}
// Usage writes application usage to w. It parses args to determine
// appropriate help context, such as which command to show help for.
func (a *Application) Usage(args []string) {
context, err := a.parseContext(true, args)
a.FatalIfError(err, "")
if err := a.UsageForContextWithTemplate(context, 2, a.usageTemplate); err != nil {
panic(err)
}
}
func formatAppUsage(app *ApplicationModel) string {
s := []string{app.Name}
if len(app.Flags) > 0 {
s = append(s, app.FlagSummary())
}
if len(app.Args) > 0 {
s = append(s, app.ArgSummary())
}
return strings.Join(s, " ")
}
func formatCmdUsage(app *ApplicationModel, cmd *CmdModel) string {
s := []string{app.Name, cmd.String()}
if len(cmd.Flags) > 0 {
s = append(s, cmd.FlagSummary())
}
if len(cmd.Args) > 0 {
s = append(s, cmd.ArgSummary())
}
return strings.Join(s, " ")
}
func formatFlag(haveShort bool, flag *FlagModel) string {
flagString := ""
flagName := flag.Name
if flag.IsBoolFlag() {
flagName = "[no-]" + flagName
}
if flag.Short != 0 {
flagString += fmt.Sprintf("-%c, --%s", flag.Short, flagName)
} else {
if haveShort {
flagString += fmt.Sprintf(" --%s", flagName)
} else {
flagString += fmt.Sprintf("--%s", flagName)
}
}
if !flag.IsBoolFlag() {
flagString += fmt.Sprintf("=%s", flag.FormatPlaceHolder())
}
if v, ok := flag.Value.(repeatableFlag); ok && v.IsCumulative() {
flagString += " ..."
}
return flagString
}
type templateParseContext struct {
SelectedCommand *CmdModel
*FlagGroupModel
*ArgGroupModel
}
type templateContext struct {
App *ApplicationModel
Width int
Context *templateParseContext
}
// UsageForContext displays usage information from a ParseContext (obtained from
// Application.ParseContext() or Action(f) callbacks).
func (a *Application) UsageForContext(context *ParseContext) error {
return a.UsageForContextWithTemplate(context, 2, a.usageTemplate)
}
// UsageForContextWithTemplate is the base usage function. You generally don't need to use this.
func (a *Application) UsageForContextWithTemplate(context *ParseContext, indent int, tmpl string) error {
width := guessWidth(a.usageWriter)
funcs := template.FuncMap{
"Indent": func(level int) string {
return strings.Repeat(" ", level*indent)
},
"Wrap": func(indent int, s string) string {
buf := bytes.NewBuffer(nil)
indentText := strings.Repeat(" ", indent)
doc.ToText(buf, s, indentText, " "+indentText, width-indent)
return buf.String()
},
"FormatFlag": formatFlag,
"FlagsToTwoColumns": func(f []*FlagModel) [][2]string {
rows := [][2]string{}
haveShort := false
for _, flag := range f {
if flag.Short != 0 {
haveShort = true
break
}
}
for _, flag := range f {
if !flag.Hidden {
rows = append(rows, [2]string{formatFlag(haveShort, flag), flag.HelpWithEnvar()})
}
}
return rows
},
"RequiredFlags": func(f []*FlagModel) []*FlagModel {
requiredFlags := []*FlagModel{}
for _, flag := range f {
if flag.Required {
requiredFlags = append(requiredFlags, flag)
}
}
return requiredFlags
},
"OptionalFlags": func(f []*FlagModel) []*FlagModel {
optionalFlags := []*FlagModel{}
for _, flag := range f {
if !flag.Required {
optionalFlags = append(optionalFlags, flag)
}
}
return optionalFlags
},
"ArgsToTwoColumns": func(a []*ArgModel) [][2]string {
rows := [][2]string{}
for _, arg := range a {
if !arg.Hidden {
var s string
if arg.PlaceHolder != "" {
s = arg.PlaceHolder
} else {
s = "<" + arg.Name + ">"
}
if !arg.Required {
s = "[" + s + "]"
}
rows = append(rows, [2]string{s, arg.HelpWithEnvar()})
}
}
return rows
},
"FormatTwoColumns": func(rows [][2]string) string {
buf := bytes.NewBuffer(nil)
formatTwoColumns(buf, indent, indent, width, rows)
return buf.String()
},
"FormatTwoColumnsWithIndent": func(rows [][2]string, indent, padding int) string {
buf := bytes.NewBuffer(nil)
formatTwoColumns(buf, indent, padding, width, rows)
return buf.String()
},
"FormatAppUsage": formatAppUsage,
"FormatCommandUsage": formatCmdUsage,
"IsCumulative": func(value Value) bool {
r, ok := value.(remainderArg)
return ok && r.IsCumulative()
},
"Char": func(c rune) string {
return string(c)
},
}
for k, v := range a.usageFuncs {
funcs[k] = v
}
t, err := template.New("usage").Funcs(funcs).Parse(tmpl)
if err != nil {
return err
}
var selectedCommand *CmdModel
if context.SelectedCommand != nil {
selectedCommand = context.SelectedCommand.Model()
}
ctx := templateContext{
App: a.Model(),
Width: width,
Context: &templateParseContext{
SelectedCommand: selectedCommand,
FlagGroupModel: context.flags.Model(),
ArgGroupModel: context.arguments.Model(),
},
}
return t.Execute(a.usageWriter, ctx)
}