157 lines
3.7 KiB
Go
157 lines
3.7 KiB
Go
package cli
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import (
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"io"
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"os"
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"sync"
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)
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// CLI contains the state necessary to run subcommands and parse the
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// command line arguments.
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type CLI struct {
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// Args is the list of command-line arguments received excluding
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// the name of the app. For example, if the command "./cli foo bar"
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// was invoked, then Args should be []string{"foo", "bar"}.
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Args []string
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// Commands is a mapping of subcommand names to a factory function
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// for creating that Command implementation.
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Commands map[string]CommandFactory
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// Name defines the name of the CLI.
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Name string
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// Version of the CLI.
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Version string
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// HelpFunc and HelpWriter are used to output help information, if
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// requested.
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//
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// HelpFunc is the function called to generate the generic help
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// text that is shown if help must be shown for the CLI that doesn't
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// pertain to a specific command.
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//
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// HelpWriter is the Writer where the help text is outputted to. If
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// not specified, it will default to Stderr.
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HelpFunc HelpFunc
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HelpWriter io.Writer
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once sync.Once
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isHelp bool
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subcommand string
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subcommandArgs []string
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isVersion bool
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}
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// NewClI returns a new CLI instance with sensible defaults.
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func NewCLI(app, version string) *CLI {
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return &CLI{
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Name: app,
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Version: version,
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HelpFunc: BasicHelpFunc(app),
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}
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}
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// IsHelp returns whether or not the help flag is present within the
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// arguments.
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func (c *CLI) IsHelp() bool {
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c.once.Do(c.init)
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return c.isHelp
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}
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// IsVersion returns whether or not the version flag is present within the
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// arguments.
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func (c *CLI) IsVersion() bool {
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c.once.Do(c.init)
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return c.isVersion
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}
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// Run runs the actual CLI based on the arguments given.
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func (c *CLI) Run() (int, error) {
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c.once.Do(c.init)
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// Just show the version and exit if instructed.
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if c.IsVersion() && c.Version != "" {
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c.HelpWriter.Write([]byte(c.Version + "\n"))
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return 1, nil
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}
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// Attempt to get the factory function for creating the command
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// implementation. If the command is invalid or blank, it is an error.
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commandFunc, ok := c.Commands[c.Subcommand()]
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if !ok || c.Subcommand() == "" {
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c.HelpWriter.Write([]byte(c.HelpFunc(c.Commands) + "\n"))
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return 1, nil
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}
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command, err := commandFunc()
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if err != nil {
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return 0, err
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}
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// If we've been instructed to just print the help, then print it
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if c.IsHelp() {
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c.HelpWriter.Write([]byte(command.Help() + "\n"))
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return 1, nil
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}
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return command.Run(c.SubcommandArgs()), nil
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}
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// Subcommand returns the subcommand that the CLI would execute. For
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// example, a CLI from "--version version --help" would return a Subcommand
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// of "version"
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func (c *CLI) Subcommand() string {
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c.once.Do(c.init)
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return c.subcommand
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}
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// SubcommandArgs returns the arguments that will be passed to the
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// subcommand.
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func (c *CLI) SubcommandArgs() []string {
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c.once.Do(c.init)
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return c.subcommandArgs
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}
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func (c *CLI) init() {
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if c.HelpFunc == nil {
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c.HelpFunc = BasicHelpFunc("app")
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if c.Name != "" {
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c.HelpFunc = BasicHelpFunc(c.Name)
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}
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}
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if c.HelpWriter == nil {
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c.HelpWriter = os.Stderr
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}
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c.processArgs()
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}
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func (c *CLI) processArgs() {
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for i, arg := range c.Args {
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// If the arg is a help flag, then we saw that, but don't save it.
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if arg == "-h" || arg == "-help" || arg == "--help" {
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c.isHelp = true
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continue
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}
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// Also lookup for version flag
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if arg == "-v" || arg == "-version" || arg == "--version" {
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c.isVersion = true
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continue
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}
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// If we didn't find a subcommand yet and this is the first non-flag
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// argument, then this is our subcommand. j
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if c.subcommand == "" && arg[0] != '-' {
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c.subcommand = arg
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// The remaining args the subcommand arguments
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c.subcommandArgs = c.Args[i+1:]
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}
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}
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}
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