Signed-off-by: Goutham Veeramachaneni <cs14btech11014@iith.ac.in>pull/2868/head
Goutham Veeramachaneni
9 years ago
parent
290c6b2383
commit
e3701077c3
@ -1,176 +0,0 @@ |
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// Copyright 2015 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package cli |
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import ( |
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"bytes" |
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"fmt" |
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"io" |
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"sort" |
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"strings" |
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"text/template" |
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) |
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// Command represents a single command within an application.
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type Command struct { |
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Desc string |
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Run func(t Term, args ...string) int |
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} |
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// Term handles an application's output.
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type Term interface { |
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Infof(format string, v ...interface{}) |
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Errorf(format string, v ...interface{}) |
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Out() io.Writer |
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Err() io.Writer |
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} |
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type basicTerm struct { |
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out, err io.Writer |
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} |
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// Infof implements Term.
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func (t *basicTerm) Infof(format string, v ...interface{}) { |
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fmt.Fprintf(t.err, format, v...) |
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fmt.Fprint(t.err, "\n") |
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} |
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// Errorf implements Term.
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func (t *basicTerm) Errorf(format string, v ...interface{}) { |
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fmt.Fprintf(t.err, format, v...) |
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fmt.Fprint(t.err, "\n") |
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} |
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// Out implements Term.
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func (t *basicTerm) Out() io.Writer { |
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return t.out |
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} |
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// Err implements Term.
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func (t *basicTerm) Err() io.Writer { |
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return t.err |
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} |
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// BasicTerm returns a Term writing Infof and Errorf to err and Out to out.
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func BasicTerm(out, err io.Writer) Term { |
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return &basicTerm{out: out, err: err} |
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} |
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// App represents an application that may consist of multiple commands.
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type App struct { |
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Name string |
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Help func() string |
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commands map[string]*Command |
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} |
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// NewApp creates a new application with a pre-registered help command.
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func NewApp(name string) *App { |
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app := &App{ |
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Name: name, |
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commands: map[string]*Command{}, |
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} |
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app.Register("help", &Command{ |
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Desc: "prints this help text", |
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Run: func(t Term, _ ...string) int { |
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help := app.Help |
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if help == nil { |
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help = BasicHelp(app, tmpl) |
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} |
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t.Infof(help() + "\n") |
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return 0 |
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}, |
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}) |
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return app |
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} |
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// Register adds a new command to the application.
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func (app *App) Register(name string, cmd *Command) { |
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name = strings.TrimSpace(name) |
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if name == "" { |
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panic("command name must not be empty") |
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} |
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if _, ok := app.commands[name]; ok { |
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panic("command cannot be registered twice") |
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} |
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app.commands[name] = cmd |
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} |
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// Run the application with the given arguments. Output is sent to t.
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func (app *App) Run(t Term, args ...string) int { |
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help := app.commands["help"] |
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if len(args) == 0 || strings.HasPrefix(args[0], "-") { |
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help.Run(t) |
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return 2 |
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} |
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cmd, ok := app.commands[args[0]] |
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if !ok { |
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help.Run(t) |
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return 2 |
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} |
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return cmd.Run(t, args[1:]...) |
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} |
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var tmpl = ` |
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usage: {{ .Name }} <command> [<args>] |
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Available commands: |
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{{ range .Commands }}{{ .Name }} {{ .Desc }} |
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{{ end }} |
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` |
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// BasicHelp returns a function that creates a basic help text for the application
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// with its commands.
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func BasicHelp(app *App, ts string) func() string { |
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t := template.Must(template.New("help").Parse(ts)) |
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return func() string { |
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type command struct { |
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Name, Desc string |
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} |
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cmds := []command{} |
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var maxLen int |
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names := []string{} |
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for name := range app.commands { |
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names = append(names, name) |
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if len(name) > maxLen { |
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maxLen = len(name) |
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} |
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} |
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sort.Strings(names) |
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for _, name := range names { |
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cmds = append(cmds, command{ |
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Name: name + strings.Repeat(" ", maxLen-len(name)), |
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Desc: app.commands[name].Desc, |
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}) |
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} |
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var buf bytes.Buffer |
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err := t.Execute(&buf, struct { |
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Name string |
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Commands []command |
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}{ |
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Name: app.Name, |
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Commands: cmds, |
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}) |
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if err != nil { |
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panic(fmt.Errorf("error executing help template: %s", err)) |
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} |
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return strings.TrimSpace(buf.String()) |
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} |
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} |
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