Xray-core/main/commands/base/help.go

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// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package base
import (
"bufio"
"bytes"
"fmt"
"io"
"os"
"strings"
"text/template"
"unicode"
"unicode/utf8"
)
// Help implements the 'help' command.
func Help(w io.Writer, args []string) {
cmd := RootCommand
Args:
for i, arg := range args {
for _, sub := range cmd.Commands {
if sub.Name() == arg {
cmd = sub
continue Args
}
}
// helpSuccess is the help command using as many args as possible that would succeed.
helpSuccess := CommandEnv.Exec + " help"
if i > 0 {
helpSuccess += " " + strings.Join(args[:i], " ")
}
fmt.Fprintf(os.Stderr, "%s help %s: unknown help topic. Run '%s'.\n", CommandEnv.Exec, strings.Join(args, " "), helpSuccess)
SetExitStatus(2) // failed at 'xray help cmd'
Exit()
}
if len(cmd.Commands) > 0 {
PrintUsage(os.Stdout, cmd)
} else {
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buildCommandText(cmd)
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tmpl(os.Stdout, helpTemplate, makeTmplData(cmd))
}
}
var usageTemplate = `{{.Long | trim}}
Usage:
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{{.UsageLine}} <command> [arguments]
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The commands are:
{{range .Commands}}{{if and (ne .Short "") (or (.Runnable) .Commands)}}
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{{.Name | width $.CommandsWidth}} {{.Short}}{{end}}{{end}}
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Use "{{.Exec}} help{{with .LongName}} {{.}}{{end}} <command>" for more information about a command.
`
// APPEND FOLLOWING TO 'usageTemplate' IF YOU WANT DOC,
// A DOC TOPIC IS JUST A COMMAND NOT RUNNABLE:
//
// {{if eq (.UsageLine) (.Exec)}}
// Additional help topics:
// {{range .Commands}}{{if and (not .Runnable) (not .Commands)}}
// {{.Name | printf "%-15s"}} {{.Short}}{{end}}{{end}}
//
// Use "{{.Exec}} help{{with .LongName}} {{.}}{{end}} <topic>" for more information about that topic.
// {{end}}
var helpTemplate = `{{if .Runnable}}usage: {{.UsageLine}}
{{end}}{{.Long | trim}}
`
// An errWriter wraps a writer, recording whether a write error occurred.
type errWriter struct {
w io.Writer
err error
}
func (w *errWriter) Write(b []byte) (int, error) {
n, err := w.w.Write(b)
if err != nil {
w.err = err
}
return n, err
}
// tmpl executes the given template text on data, writing the result to w.
func tmpl(w io.Writer, text string, data interface{}) {
t := template.New("top")
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t.Funcs(template.FuncMap{"trim": strings.TrimSpace, "capitalize": capitalize, "width": width})
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template.Must(t.Parse(text))
ew := &errWriter{w: w}
err := t.Execute(ew, data)
if ew.err != nil {
// I/O error writing. Ignore write on closed pipe.
if strings.Contains(ew.err.Error(), "pipe") {
SetExitStatus(1)
Exit()
}
Fatalf("writing output: %v", ew.err)
}
if err != nil {
panic(err)
}
}
func capitalize(s string) string {
if s == "" {
return s
}
r, n := utf8.DecodeRuneInString(s)
return string(unicode.ToTitle(r)) + s[n:]
}
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func width(width int, value string) string {
format := fmt.Sprintf("%%-%ds", width)
return fmt.Sprintf(format, value)
}
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// PrintUsage prints usage of cmd to w
func PrintUsage(w io.Writer, cmd *Command) {
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buildCommandText(cmd)
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bw := bufio.NewWriter(w)
tmpl(bw, usageTemplate, makeTmplData(cmd))
bw.Flush()
}
// buildCommandText build command text as template
func buildCommandText(cmd *Command) {
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data := makeTmplData(cmd)
cmd.UsageLine = buildText(cmd.UsageLine, data)
// DO NOT SUPPORT ".Short":
// - It's not necessary
// - Or, we have to build text for all sub commands of current command, like "xray help api"
// cmd.Short = buildText(cmd.Short, data)
cmd.Long = buildText(cmd.Long, data)
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}
func buildText(text string, data interface{}) string {
buf := bytes.NewBuffer([]byte{})
tmpl(buf, text, data)
return buf.String()
}
type tmplData struct {
*Command
*CommandEnvHolder
}
func makeTmplData(cmd *Command) tmplData {
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// Minimum width of the command column
width := 12
for _, c := range cmd.Commands {
l := len(c.Name())
if width < l {
width = l
}
}
CommandEnv.CommandsWidth = width
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return tmplData{
Command: cmd,
CommandEnvHolder: &CommandEnv,
}
}