terraform/vendor/github.com/mitchellh/cli/cli.go

391 lines
10 KiB
Go

package cli
import (
"fmt"
"io"
"os"
"sort"
"strings"
"sync"
"text/template"
"github.com/armon/go-radix"
)
// CLI contains the state necessary to run subcommands and parse the
// command line arguments.
//
// CLI also supports nested subcommands, such as "cli foo bar". To use
// nested subcommands, the key in the Commands mapping below contains the
// full subcommand. In this example, it would be "foo bar".
//
// If you use a CLI with nested subcommands, some semantics change due to
// ambiguities:
//
// * We use longest prefix matching to find a matching subcommand. This
// means if you register "foo bar" and the user executes "cli foo qux",
// the "foo" commmand will be executed with the arg "qux". It is up to
// you to handle these args. One option is to just return the special
// help return code `RunResultHelp` to display help and exit.
//
// * The help flag "-h" or "-help" will look at all args to determine
// the help function. For example: "otto apps list -h" will show the
// help for "apps list" but "otto apps -h" will show it for "apps".
// In the normal CLI, only the first subcommand is used.
//
// * The help flag will list any subcommands that a command takes
// as well as the command's help itself. If there are no subcommands,
// it will note this. If the CLI itself has no subcommands, this entire
// section is omitted.
//
// * Any parent commands that don't exist are automatically created as
// no-op commands that just show help for other subcommands. For example,
// if you only register "foo bar", then "foo" is automatically created.
//
type CLI struct {
// Args is the list of command-line arguments received excluding
// the name of the app. For example, if the command "./cli foo bar"
// was invoked, then Args should be []string{"foo", "bar"}.
Args []string
// Commands is a mapping of subcommand names to a factory function
// for creating that Command implementation. If there is a command
// with a blank string "", then it will be used as the default command
// if no subcommand is specified.
//
// If the key has a space in it, this will create a nested subcommand.
// For example, if the key is "foo bar", then to access it our CLI
// must be accessed with "./cli foo bar". See the docs for CLI for
// notes on how this changes some other behavior of the CLI as well.
Commands map[string]CommandFactory
// Name defines the name of the CLI.
Name string
// Version of the CLI.
Version string
// HelpFunc and HelpWriter are used to output help information, if
// requested.
//
// HelpFunc is the function called to generate the generic help
// text that is shown if help must be shown for the CLI that doesn't
// pertain to a specific command.
//
// HelpWriter is the Writer where the help text is outputted to. If
// not specified, it will default to Stderr.
HelpFunc HelpFunc
HelpWriter io.Writer
once sync.Once
commandTree *radix.Tree
commandNested bool
isHelp bool
subcommand string
subcommandArgs []string
topFlags []string
isVersion bool
}
// NewClI returns a new CLI instance with sensible defaults.
func NewCLI(app, version string) *CLI {
return &CLI{
Name: app,
Version: version,
HelpFunc: BasicHelpFunc(app),
}
}
// IsHelp returns whether or not the help flag is present within the
// arguments.
func (c *CLI) IsHelp() bool {
c.once.Do(c.init)
return c.isHelp
}
// IsVersion returns whether or not the version flag is present within the
// arguments.
func (c *CLI) IsVersion() bool {
c.once.Do(c.init)
return c.isVersion
}
// Run runs the actual CLI based on the arguments given.
func (c *CLI) Run() (int, error) {
c.once.Do(c.init)
// Just show the version and exit if instructed.
if c.IsVersion() && c.Version != "" {
c.HelpWriter.Write([]byte(c.Version + "\n"))
return 1, nil
}
// If there is an invalid flag, then error
if len(c.topFlags) > 0 {
c.HelpWriter.Write([]byte(
"Invalid flags before the subcommand. If these flags are for\n" +
"the subcommand, please put them after the subcommand.\n\n"))
c.HelpWriter.Write([]byte(c.HelpFunc(c.Commands) + "\n"))
return 1, nil
}
// Attempt to get the factory function for creating the command
// implementation. If the command is invalid or blank, it is an error.
raw, ok := c.commandTree.Get(c.Subcommand())
if !ok {
c.HelpWriter.Write([]byte(c.HelpFunc(c.Commands) + "\n"))
return 1, nil
}
command, err := raw.(CommandFactory)()
if err != nil {
return 0, err
}
// If we've been instructed to just print the help, then print it
if c.IsHelp() {
c.commandHelp(command)
return 1, nil
}
code := command.Run(c.SubcommandArgs())
if code == RunResultHelp {
// Requesting help
c.commandHelp(command)
return 1, nil
}
return code, nil
}
// Subcommand returns the subcommand that the CLI would execute. For
// example, a CLI from "--version version --help" would return a Subcommand
// of "version"
func (c *CLI) Subcommand() string {
c.once.Do(c.init)
return c.subcommand
}
// SubcommandArgs returns the arguments that will be passed to the
// subcommand.
func (c *CLI) SubcommandArgs() []string {
c.once.Do(c.init)
return c.subcommandArgs
}
func (c *CLI) init() {
if c.HelpFunc == nil {
c.HelpFunc = BasicHelpFunc("app")
if c.Name != "" {
c.HelpFunc = BasicHelpFunc(c.Name)
}
}
if c.HelpWriter == nil {
c.HelpWriter = os.Stderr
}
// Build our command tree
c.commandTree = radix.New()
c.commandNested = false
for k, v := range c.Commands {
k = strings.TrimSpace(k)
c.commandTree.Insert(k, v)
if strings.ContainsRune(k, ' ') {
c.commandNested = true
}
}
// Go through the key and fill in any missing parent commands
if c.commandNested {
var walkFn radix.WalkFn
toInsert := make(map[string]struct{})
walkFn = func(k string, raw interface{}) bool {
idx := strings.LastIndex(k, " ")
if idx == -1 {
// If there is no space, just ignore top level commands
return false
}
// Trim up to that space so we can get the expected parent
k = k[:idx]
if _, ok := c.commandTree.Get(k); ok {
// Yay we have the parent!
return false
}
// We're missing the parent, so let's insert this
toInsert[k] = struct{}{}
// Call the walk function recursively so we check this one too
return walkFn(k, nil)
}
// Walk!
c.commandTree.Walk(walkFn)
// Insert any that we're missing
for k, _ := range toInsert {
var f CommandFactory = func() (Command, error) {
return &MockCommand{
HelpText: "This command is accessed by using one of the subcommands below.",
RunResult: RunResultHelp,
}, nil
}
c.commandTree.Insert(k, f)
}
}
// Process the args
c.processArgs()
}
func (c *CLI) commandHelp(command Command) {
// Get the template to use
tpl := strings.TrimSpace(defaultHelpTemplate)
if t, ok := command.(CommandHelpTemplate); ok {
tpl = t.HelpTemplate()
}
if !strings.HasSuffix(tpl, "\n") {
tpl += "\n"
}
// Parse it
t, err := template.New("root").Parse(tpl)
if err != nil {
t = template.Must(template.New("root").Parse(fmt.Sprintf(
"Internal error! Failed to parse command help template: %s\n", err)))
}
// Template data
data := map[string]interface{}{
"Name": c.Name,
"Help": command.Help(),
}
// Build subcommand list if we have it
var subcommands []map[string]interface{}
if c.commandNested {
// Get the matching keys
var keys []string
prefix := c.Subcommand() + " "
c.commandTree.WalkPrefix(prefix, func(k string, raw interface{}) bool {
keys = append(keys, k)
return false
})
// Sort the keys
sort.Strings(keys)
// Figure out the padding length
var longest int
for _, k := range keys {
if v := len(k); v > longest {
longest = v
}
}
// Go through and create their structures
subcommands = make([]map[string]interface{}, len(keys))
for i, k := range keys {
raw, ok := c.commandTree.Get(k)
if !ok {
// We just checked that it should be here above. If it is
// isn't, there are serious problems.
panic("value is missing")
}
// Get the command
sub, err := raw.(CommandFactory)()
if err != nil {
c.HelpWriter.Write([]byte(fmt.Sprintf(
"Error instantiating %q: %s", k, err)))
}
// Determine some info
name := strings.TrimPrefix(k, prefix)
subcommands[i] = map[string]interface{}{
"Name": name,
"NameAligned": name + strings.Repeat(" ", longest-len(k)),
"Help": sub.Help(),
"Synopsis": sub.Synopsis(),
}
}
}
data["Subcommands"] = subcommands
// Write
err = t.Execute(c.HelpWriter, data)
if err == nil {
return
}
// An error, just output...
c.HelpWriter.Write([]byte(fmt.Sprintf(
"Internal error rendering help: %s", err)))
}
func (c *CLI) processArgs() {
for i, arg := range c.Args {
if c.subcommand == "" {
// Check for version and help flags if not in a subcommand
if arg == "-v" || arg == "-version" || arg == "--version" {
c.isVersion = true
continue
}
if arg == "-h" || arg == "-help" || arg == "--help" {
c.isHelp = true
continue
}
if arg != "" && arg[0] == '-' {
// Record the arg...
c.topFlags = append(c.topFlags, arg)
}
}
// If we didn't find a subcommand yet and this is the first non-flag
// argument, then this is our subcommand. j
if c.subcommand == "" && arg != "" && arg[0] != '-' {
c.subcommand = arg
if c.commandNested {
// Nested CLI, the subcommand is actually the entire
// arg list up to a flag that is still a valid subcommand.
k, _, ok := c.commandTree.LongestPrefix(strings.Join(c.Args[i:], " "))
if ok {
c.subcommand = k
i += strings.Count(k, " ")
}
}
// The remaining args the subcommand arguments
c.subcommandArgs = c.Args[i+1:]
}
}
// If we never found a subcommand and support a default command, then
// switch to using that.
if c.subcommand == "" {
if _, ok := c.Commands[""]; ok {
args := c.topFlags
args = append(args, c.subcommandArgs...)
c.topFlags = nil
c.subcommandArgs = args
}
}
}
const defaultHelpTemplate = `
{{.Help}}{{if gt (len .Subcommands) 0}}
Subcommands:
{{ range $value := .Subcommands }}
{{ $value.NameAligned }} {{ $value.Synopsis }}{{ end }}
{{ end }}
`