Merge pull request #9 from cdr/pflag

Support POSIX flags

Author: Nathan Potter

.gitignore

@@ -0,0 +1 @@
+vendor

README.md

@@ -7,8 +7,8 @@ A minimal, command-oriented CLI package.
 ## Features
 
 - Very small, simple API.
-- Uses standard `flag` package as much as possible.
-- No external dependencies.
+- Support for POSIX flags.
+- Only external dependency is [spf13/pflag](https://github.com/spf13/pflag).
 - Subcommands.
 - Auto-generated help.
 
@@ -37,7 +37,7 @@ type cmd struct {
     verbose bool
 }
 
-func (c *cmd) Run(fl *flag.FlagSet) {
+func (c *cmd) Run(fl *pflag.FlagSet) {
     if c.verbose {
         fmt.Println("verbose enabled")
     }
@@ -52,7 +52,7 @@ func (c *cmd) Spec() cli.CommandSpec {
     }
 }
 
-func (c *cmd) RegisterFlags(fl *flag.FlagSet) {
+func (c *cmd) RegisterFlags(fl *pflag.FlagSet) {
     fl.BoolVar(&c.verbose, "v", false, "sets verbose mode")
 }
 
@@ -87,7 +87,7 @@ import (
 type subcmd struct {
 }
 
-func (c *subcmd) Run(fl *flag.FlagSet) {
+func (c *subcmd) Run(fl *pflag.FlagSet) {
     fmt.Println("subcommand invoked")
 }
 
@@ -102,7 +102,7 @@ func (c *subcmd) Spec() cli.CommandSpec {
 type cmd struct {
 }
 
-func (c *cmd) Run(fl *flag.FlagSet) {
+func (c *cmd) Run(fl *pflag.FlagSet) {
     // This root command has no default action, so print the help.
     fl.Usage()
 }

command.go

@@ -1,8 +1,9 @@
 package cli
 
 import (
-	"flag"
 	"strings"
+
+	"github.com/spf13/pflag"
 )
 
 // CommandSpec describes a Command's usage.
@@ -38,7 +39,7 @@ type Command interface {
 	// Spec returns metadata about the command.
 	Spec() CommandSpec
 	// Run invokes the command's main routine with parsed flags.
-	Run(fl *flag.FlagSet)
+	Run(fl *pflag.FlagSet)
 }
 
 // ParentCommand is an optional interface for commands that have subcommands.
@@ -52,5 +53,5 @@ type ParentCommand interface {
 // FlaggedCommand is an optional interface for commands that have flags.
 type FlaggedCommand interface {
 	// RegisterFlags lets the command register flags which be sent to Handle.
-	RegisterFlags(fl *flag.FlagSet)
+	RegisterFlags(fl *pflag.FlagSet)
 }

examples/simple/main.go

@@ -1,17 +1,17 @@
 package main
 
 import (
-	"flag"
 	"fmt"
 
+	"github.com/spf13/pflag"
 	"go.coder.com/cli"
 )
 
 type cmd struct {
 	verbose bool
 }
 
-func (c *cmd) Run(fl *flag.FlagSet) {
+func (c *cmd) Run(fl *pflag.FlagSet) {
 	if c.verbose {
 		fmt.Println("verbose enabled")
 	}
@@ -26,8 +26,8 @@ func (c *cmd) Spec() cli.CommandSpec {
 	}
 }
 
-func (c *cmd) RegisterFlags(fl *flag.FlagSet) {
-	fl.BoolVar(&c.verbose, "v", false, "sets verbose mode")
+func (c *cmd) RegisterFlags(fl *pflag.FlagSet) {
+	fl.BoolVarP(&c.verbose, "verbose", "v", false, "sets verbose mode")
 }
 
 func main() {

examples/subcommands/main.go

@@ -1,16 +1,16 @@
 package main
 
 import (
-	"flag"
 	"fmt"
 
+	"github.com/spf13/pflag"
 	"go.coder.com/cli"
 )
 
 type subcmd struct {
 }
 
-func (c *subcmd) Run(fl *flag.FlagSet) {
+func (c *subcmd) Run(fl *pflag.FlagSet) {
 	fmt.Println("subcommand invoked")
 }
 
@@ -25,7 +25,7 @@ func (c *subcmd) Spec() cli.CommandSpec {
 type cmd struct {
 }
 
-func (c *cmd) Run(fl *flag.FlagSet) {
+func (c *cmd) Run(fl *pflag.FlagSet) {
 	// This root command has no default action, so print the help.
 	fl.Usage()
 }

go.mod

@@ -1,3 +1,5 @@
 module go.coder.com/cli
 
 go 1.12
+
+require github.com/spf13/pflag v1.0.3

go.sum

@@ -0,0 +1,2 @@
+github.com/spf13/pflag v1.0.3 h1:zPAT6CGy6wXeQ7NtTnaTerfKOsV6V6F8agHXFiazDkg=
+github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=

help.go

@@ -1,13 +1,14 @@
 package cli
 
 import (
-	"flag"
 	"fmt"
 	"io"
 	"strings"
 	"text/tabwriter"
 	"unicode"
 	"unicode/utf8"
+
+	"github.com/spf13/pflag"
 )
 
 func flagDashes(name string) string {
@@ -36,35 +37,26 @@ func fmtDefValue(value interface{}) string {
 // \xFF is used to escape a \t so tabwriter ignores it.
 const tabEscape = "\xFF"
 
-func renderFlagHelp(fl *flag.FlagSet, w io.Writer) {
-	var count int
-	fl.VisitAll(func(f *flag.Flag) {
-		if count == 0 {
-			fmt.Fprintf(w, "\n%v flags:\n", fl.Name())
-		}
-
-		count++
-		if f.DefValue == "" {
-			fmt.Fprintf(w, tabEscape+"\t%v%v\t%v\n", flagDashes(f.Name), f.Name, f.Usage)
-		} else {
-			fmt.Fprintf(w, tabEscape+"\t%v%v=%v\t%v\n", flagDashes(f.Name), f.Name, fmtDefValue(f.DefValue), f.Usage)
-		}
-	})
+func renderFlagHelp(fullName string, fl *pflag.FlagSet, w io.Writer) {
+	if fl.HasFlags() {
+		fmt.Fprintf(w, "\n%s flags:\n", fullName)
+		fmt.Fprint(w, fl.FlagUsages())
+	}
 }
 
 // renderHelp generates a command's help page.
-func renderHelp(cmd Command, fl *flag.FlagSet, w io.Writer) {
+func renderHelp(fullName string, cmd Command, fl *pflag.FlagSet, w io.Writer) {
 	// Render usage and description.
 	fmt.Fprintf(w, "Usage: %v %v\n\n",
-		fl.Name(), cmd.Spec().Usage,
+		fullName, cmd.Spec().Usage,
 	)
 	fmt.Fprintf(w, "%v\n", cmd.Spec().Desc)
 
 	tw := tabwriter.NewWriter(w, 0, 4, 2, ' ', tabwriter.StripEscape)
 	defer tw.Flush()
 
 	// Render flag help.
-	renderFlagHelp(fl, tw)
+	renderFlagHelp(fullName, fl, tw)
 
 	// Render subcommand summaries.
 	pc, ok := cmd.(ParentCommand)

run.go

@@ -1,17 +1,36 @@
 package cli
 
 import (
-	"flag"
 	"os"
+	"strings"
+
+	"github.com/spf13/pflag"
 )
 
 func appendParent(parent string, add string) string {
-	if parent == "" {
-		return add + " "
-	}
 	return parent + add + " "
 }
 
+// splitArgs tries to split the args between the parent command's flags/args, and the subcommand's
+// flags/args. If a subcommand is found, the parent args, subcommand args, and the subcommand will
+// be returned. If a subcommand isn't found, the args will be returned as is, the subcommand args
+// will be empty, and the subcommand will be nil.
+func splitArgs(subCmds []Command, args []string) (cmdArgs, subArgs []string, subCmd Command) {
+	for i, arg := range args {
+		if strings.HasPrefix(arg, "-") {
+			continue
+		}
+
+		for _, subCommand := range subCmds {
+			if subCommand.Spec().Name == arg {
+				return args[:i], args[i+1:], subCommand
+			}
+		}
+	}
+
+	return args, []string{}, nil
+}
+
 // Run sets up flags, helps, and executes the command with the provided
 // arguments.
 //
@@ -20,37 +39,51 @@ func appendParent(parent string, add string) string {
 //
 // Use RunRoot if this package is managing the entire CLI.
 func Run(cmd Command, args []string, parent string) {
-	fl := flag.NewFlagSet(parent+""+cmd.Spec().Name, flag.ExitOnError)
+	name := parent + cmd.Spec().Name
+	fl := pflag.NewFlagSet(name, pflag.ContinueOnError)
+	// Ensure pflag library doesn't print usage for us automatically,
+	// we'll override this below.
+	fl.Usage = func() {}
 
 	if fc, ok := cmd.(FlaggedCommand); ok {
 		fc.RegisterFlags(fl)
 	}
 
-	fl.Usage = func() {
-		renderHelp(cmd, fl, os.Stderr)
-	}
-
 	if cmd.Spec().RawArgs {
 		// Use `--` to return immediately when parsing the flags.
 		args = append([]string{"--"}, args...)
 	}
-	_ = fl.Parse(args)
 
-	subcommandArg := fl.Arg(0)
+	var (
+		cmdArgs, subArgs []string
+		subCmd           Command
+	)
+	pc, isParentCmd := cmd.(ParentCommand)
+	if isParentCmd {
+		cmdArgs, subArgs, subCmd = splitArgs(pc.Subcommands(), args)
+		if subCmd != nil {
+			args = cmdArgs
+		}
+	}
 
-	// Route to subcommand.
-	if pc, ok := cmd.(ParentCommand); ok && subcommandArg != "" {
-		for _, subcommand := range pc.Subcommands() {
-			if subcommand.Spec().Name != subcommandArg {
-				continue
-			}
+	err := fl.Parse(args)
+	// Reassign the usage now that we've parsed the args
+	// so that we can render it manually.
+	fl.Usage = func() {
+		renderHelp(name, cmd, fl, os.Stderr)
+	}
+	if err != nil {
+		fl.Usage()
+		os.Exit(2)
+	}
 
-			Run(
-				subcommand, fl.Args()[1:],
-				appendParent(parent, cmd.Spec().Name),
-			)
-			return
-		}
+	// Route to subcommand.
+	if isParentCmd && subCmd != nil {
+		Run(
+			subCmd, subArgs,
+			appendParent(parent, cmd.Spec().Name),
+		)
+		return
 	}
 
 	cmd.Run(fl)