spf13--cobra/commander.go

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// Copyright © 2013 Steve Francia <spf@spf13.com>.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Commands similar to git, go tools and other modern CLI tools
// inspired by go, go-Commander, gh and subcommand
package cobra
import (
"fmt"
"io"
"os"
)
// A Commander holds the configuration for the command line tool.
type Commander struct {
// A Commander is also a Command for top level and global help & flags
Command
args []string
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output *io.Writer // nil means stderr; use out() accessor
UsageFunc func(*Command) error // Usage can be defined by application
UsageTemplate string // Can be defined by Application
HelpTemplate string // Can be defined by Application
HelpFunc func(*Command, []string) // Help can be defined by application
HelpCommand *Command
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}
// Provide the user with a new commander.
func NewCommander() (c *Commander) {
c = new(Commander)
c.cmdr = c
c.UsageFunc = c.defaultUsage
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c.HelpFunc = c.defaultHelp
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c.initTemplates()
return
}
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func (c *Commander) initHelp() {
if c.HelpCommand == nil {
c.HelpCommand = &Command{
Use: "help [command to learn about]",
Short: "Help about any command",
Long: `Help provides help for any command in the application.
Simply type ` + c.Name() + ` help [path to command] for full details.`,
Run: c.HelpFunc,
}
}
c.AddCommand(c.HelpCommand)
}
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// Name for commander, should match application name
func (c *Commander) SetName(name string) {
c.name = name
}
// os.Args[1:] by default, if desired, can be overridden
// particularly useful when testing.
func (c *Commander) SetArgs(a []string) {
c.args = a
}
// Call execute to use the args (os.Args[1:] by default)
// and run through the command tree finding appropriate matches
// for commands and then corresponding flags.
func (c *Commander) Execute() (err error) {
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// initialize help as the last point possible to allow for user
// overriding
c.initHelp()
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if len(c.args) == 0 {
err = c.execute(os.Args[1:])
} else {
err = c.execute(c.args)
}
return
}
func (c *Commander) out() io.Writer {
if c.output == nil {
return os.Stderr
}
return *c.output
}
func (cmdr *Commander) defaultUsage(c *Command) error {
err := tmpl(cmdr.out(), cmdr.UsageTemplate, c)
return err
}
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func (cmdr *Commander) defaultHelp(c *Command, args []string) {
cmd, _, e := c.Root().Find(args)
if cmd == nil {
cmdr.Printf("Unknown help topic %#q. Run '%v help'.\n", args, cmdr.Name())
return
}
if e != nil {
cmdr.Printf("Unknown help topic %#q. Run '%v help'.\n", args, cmdr.Name())
} else {
err := tmpl(cmdr.out(), cmdr.HelpTemplate, cmd)
if err != nil {
c.Println(err)
}
}
}
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//Print to out
func (c *Commander) PrintOut(i ...interface{}) {
fmt.Fprint(c.out(), i...)
}
// SetOutput sets the destination for usage and error messages.
// If output is nil, os.Stderr is used.
func (c *Commander) SetOutput(output io.Writer) {
c.output = &output
}
func (c *Commander) initTemplates() {
c.UsageTemplate = `{{ $cmd := . }}
Usage: {{if .Runnable}}
{{.UseLine}}{{if .HasFlags}} [flags]{{end}}{{end}}{{if .HasSubCommands}}
{{ .CommandPath}} [command]{{end}}
{{ if .HasSubCommands}}
Available Commands: {{range .Commands}}{{if .Runnable}}
{{.Use | printf "%-11s"}} :: {{.Short}}{{end}}{{end}}
{{end}}
{{ if .HasFlags}} Available Flags:
{{.Flags.FlagUsages}}{{end}}{{if and (gt .Commands 0) (gt .Parent.Commands 1) }}
Additional help topics: {{if gt .Commands 0 }}{{range .Commands}}{{if not .Runnable}}
{{.CommandPath | printf "%-11s"}} :: {{.Short}}{{end}}{{end}}{{end}}{{if gt .Parent.Commands 1 }}{{range .Parent.Commands}}{{if .Runnable}}{{if not (eq .Name $cmd.Name) }}{{end}}
{{.CommandPath | printf "%-11s"}} :: {{.Short}}{{end}}{{end}}{{end}}
{{end}}
Use "{{.Commander.Name}} help [command]" for more information about that command.
`
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c.HelpTemplate = `{{.Name}}
{{.Long | trim}}
{{if .Runnable}}{{.Usage}}{{end}}
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`
}