v1.0.0

main/commands/base/help.go

@@ -0,0 +1,157 @@
+// 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 {
+		tmpl(os.Stdout, helpTemplate, makeTmplData(cmd))
+	}
+}
+
+var usageTemplate = `{{.Long | trim}}
+
+Usage:
+
+	{{.Exec}} <command> [arguments]
+
+The commands are:
+{{range .Commands}}{{if and (ne .Short "") (or (.Runnable) .Commands)}}
+	{{.Name | printf "%-12s"}} {{.Short}}{{end}}{{end}}
+
+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")
+	t.Funcs(template.FuncMap{"trim": strings.TrimSpace, "capitalize": capitalize})
+	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:]
+}
+
+// PrintUsage prints usage of cmd to w
+func PrintUsage(w io.Writer, cmd *Command) {
+	bw := bufio.NewWriter(w)
+	tmpl(bw, usageTemplate, makeTmplData(cmd))
+	bw.Flush()
+}
+
+// buildCommandsText build text of command and its children as template
+func buildCommandsText(cmd *Command) {
+	buildCommandText(cmd)
+	for _, cmd := range cmd.Commands {
+		buildCommandsText(cmd)
+	}
+}
+
+// buildCommandText build command text as template
+func buildCommandText(cmd *Command) {
+	cmd.UsageLine = buildText(cmd.UsageLine, makeTmplData(cmd))
+	cmd.Short = buildText(cmd.Short, makeTmplData(cmd))
+	cmd.Long = buildText(cmd.Long, makeTmplData(cmd))
+}
+
+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 {
+	return tmplData{
+		Command:          cmd,
+		CommandEnvHolder: &CommandEnv,
+	}
+}