start autocomplete support

1 files changed, 222 insertions, 0 deletions

diff --git a/complete.go b/complete.go
new file mode 100644
index 0000000..72f964d
--- /dev/null
+++ b/complete.go
@@ -0,0 +1,222 @@
+package arg
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+// has the variables for autocomplete
+type Complete struct {
+	Subcommand []string  // this will be sent from the shell autocomplete scheme
+	Partial    string    // whatever the user has partially entered on the commandline
+	Stderr     io.Writer // this is where Stderr
+	Stdout     io.Writer // this is where Stdout
+}
+
+// same as WriteHelpForSubcommand above, but can flip to STDERR and STDOUT
+// most shell autocomplete behavior usually wants things that way
+func (p *Parser) WriteHelpForAutocomplete(stderr io.Writer, stdout io.Writer, partial string, subcommand ...string) error {
+	var automatch []string
+	if stderr == nil {
+		stderr = os.Stderr
+	}
+	cmd, err := p.lookupCommand(subcommand...)
+	if err != nil {
+		return err
+	}
+
+	var positionals, longOptions, shortOptions, envOnlyOptions []*spec
+	var hasVersionOption bool
+	for _, spec := range cmd.specs {
+		switch {
+		case spec.positional:
+			positionals = append(positionals, spec)
+		case spec.long != "":
+			longOptions = append(longOptions, spec)
+			if spec.long == "version" {
+				hasVersionOption = true
+			}
+		case spec.short != "":
+			shortOptions = append(shortOptions, spec)
+		case spec.short == "" && spec.long == "":
+			envOnlyOptions = append(envOnlyOptions, spec)
+		}
+	}
+
+	// obtain a flattened list of options from all ancestors
+	// also determine if any ancestor has a version option spec
+	var globals []*spec
+	ancestor := cmd.parent
+	for ancestor != nil {
+		for _, spec := range ancestor.specs {
+			if spec.long == "version" {
+				hasVersionOption = true
+				break
+			}
+		}
+		globals = append(globals, ancestor.specs...)
+		ancestor = ancestor.parent
+	}
+
+	if p.description != "" {
+		fmt.Fprintln(stderr, p.description)
+	}
+
+	if !hasVersionOption && p.version != "" {
+		fmt.Fprintln(stderr, p.version)
+	}
+
+	p.WriteUsageForSubcommand(stderr, subcommand...)
+
+	// write the list of positionals
+	if len(positionals) > 0 {
+		fmt.Fprint(stderr, "\nPositional arguments:\n")
+		for _, spec := range positionals {
+			print(stderr, spec.placeholder, spec.help, withDefault(spec.defaultString), withEnv(spec.env))
+		}
+	}
+
+	// write the list of options with the short-only ones first to match the usage string
+	if len(shortOptions)+len(longOptions) > 0 || cmd.parent == nil {
+		fmt.Fprint(stderr, "\nOptions:\n")
+		for _, spec := range shortOptions {
+			p.printOption(stderr, spec)
+		}
+		for _, spec := range longOptions {
+			p.printOption(stderr, spec)
+			//jwc
+			if strings.HasPrefix(spec.long, partial) {
+				automatch = append(automatch, "--"+spec.long)
+			}
+		}
+	}
+
+	// write the list of global options
+	if len(globals) > 0 {
+		fmt.Fprint(stderr, "\nGlobal options:\n")
+		for _, spec := range globals {
+			p.printOption(stderr, spec)
+		}
+	}
+
+	// write the list of built in options
+	p.printOption(stderr, &spec{
+		cardinality: zero,
+		long:        "help",
+		short:       "h",
+		help:        "display this help and exit",
+	})
+	if !hasVersionOption && p.version != "" {
+		p.printOption(stderr, &spec{
+			cardinality: zero,
+			long:        "version",
+			help:        "display version and exit",
+		})
+	}
+
+	// write the list of environment only variables
+	if len(envOnlyOptions) > 0 {
+		fmt.Fprint(stderr, "\nEnvironment variables:\n")
+		for _, spec := range envOnlyOptions {
+			p.printEnvOnlyVar(stderr, spec)
+		}
+	}
+
+	// write the list of subcommands
+	if len(cmd.subcommands) > 0 {
+		fmt.Fprint(stderr, "\nCommands:\n")
+		for _, subcmd := range cmd.subcommands {
+			names := append([]string{subcmd.name}, subcmd.aliases...)
+			print(stderr, strings.Join(names, ", "), subcmd.help)
+			if strings.HasPrefix(subcmd.name, partial) {
+				automatch = append(automatch, subcmd.name)
+			}
+		}
+	}
+
+	if p.epilogue != "" {
+		fmt.Fprintln(stderr, "\n"+p.epilogue)
+	}
+
+	if stdout == nil {
+		fmt.Fprintf(os.Stdout, "err foo")
+	} else {
+		// writes out the shell autocomplete matches
+		if len(automatch) > 0 {
+			fmt.Fprintf(stdout, "%s", strings.Join(automatch, " "))
+		}
+	}
+	return nil
+}
+
+// GetUsageForSubcommand gets the commands for bash shell completetion
+func (p *Parser) GetUsageForSubcommand(stdout io.Writer, stderr io.Writer, partial string, s string) (string, error) {
+	var log []string
+	var final []string
+	cmd, err := p.lookupCommand(s)
+	if err != nil {
+		return "", err
+	}
+
+	var positionals, longOptions, shortOptions []*spec
+	for _, spec := range cmd.specs {
+		switch {
+		case spec.positional:
+			positionals = append(positionals, spec)
+		case spec.long != "":
+			longOptions = append(longOptions, spec)
+		case spec.short != "":
+			shortOptions = append(shortOptions, spec)
+		}
+	}
+
+	// write the option component of the usage message
+	for _, spec := range shortOptions {
+		// prefix with a space
+		log = append(log, fmt.Sprintf(" "))
+		if !spec.required {
+			// log = append(log, fmt.Sprintf("["))
+		}
+		log = append(log, synopsis(spec, "-"+spec.short))
+		if !spec.required {
+			// log = append(log, fmt.Sprintf("]"))
+		}
+	}
+
+	for _, spec := range longOptions {
+		// prefix with a space
+		if !spec.required {
+			// log = append(log, fmt.Sprintf("["))
+		}
+		log = append(log, synopsis(spec, "--"+spec.long))
+		if !spec.required {
+			// log = append(log, fmt.Sprintf("]"))
+		}
+	}
+
+	for _, spec := range positionals {
+		if !spec.required {
+			// log = append(log, fmt.Sprintf("["))
+		}
+		if spec.cardinality == multiple {
+			log = append(log, fmt.Sprintf("%s [%s ...]", spec.placeholder, spec.placeholder))
+		} else {
+			log = append(log, spec.placeholder)
+		}
+	}
+	for _, subcmd := range cmd.subcommands {
+		names := append([]string{subcmd.name}, subcmd.aliases...)
+		if strings.HasPrefix(subcmd.name, partial) {
+			final = append(final, subcmd.name)
+		}
+		log = append(log, strings.Join(names, ", "), subcmd.help)
+		if stderr != nil {
+			print(stderr, strings.Join(names, ", "), subcmd.help)
+		}
+	}
+	fmt.Fprintf(stdout, "%s", strings.Join(final, " "))
+
+	return strings.Join(final, " "), nil
+}