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@aviddiviner @kbatten @mboersma @th0114nd
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// Licensed under terms of MIT license (see LICENSE-MIT)
// Copyright (c) 2013 Keith Batten, kbatten@gmail.com
// Copyright (c) 2016 David Irvine
package docopt
import (
"fmt"
"os"
"regexp"
"strings"
)
type Parser struct {
// HelpHandler is called when we encounter bad user input, or when the user
// asks for help.
// By default, this calls os.Exit(0) if it handled a built-in option such
// as -h, --help or --version. If the user errored with a wrong command or
// options, we exit with a return code of 1.
HelpHandler func(err error, usage string)
// OptionsFirst requires that option flags always come before positional
// arguments; otherwise they can overlap.
OptionsFirst bool
// SkipHelpFlags tells the parser not to look for -h and --help flags and
// call the HelpHandler.
SkipHelpFlags bool
}
var PrintHelpAndExit = func(err error, usage string) {
if err != nil {
fmt.Fprintln(os.Stderr, usage)
os.Exit(1)
} else {
fmt.Println(usage)
os.Exit(0)
}
}
var PrintHelpOnly = func(err error, usage string) {
if err != nil {
fmt.Fprintln(os.Stderr, usage)
} else {
fmt.Println(usage)
}
}
var NoHelpHandler = func(err error, usage string) {}
var DefaultParser = &Parser{
HelpHandler: PrintHelpAndExit,
OptionsFirst: false,
SkipHelpFlags: false,
}
// ParseDoc parses os.Args[1:] based on the interface described in doc, using the default parser options.
func ParseDoc(doc string) (Opts, error) {
return ParseArgs(doc, nil, "")
}
// ParseArgs parses custom arguments based on the interface described in doc. If you provide a non-empty version
// string, then this will be displayed when the --version flag is found. This method uses the default parser options.
func ParseArgs(doc string, argv []string, version string) (Opts, error) {
return DefaultParser.ParseArgs(doc, argv, version)
}
// ParseArgs parses custom arguments based on the interface described in doc. If you provide a non-empty version
// string, then this will be displayed when the --version flag is found.
func (p *Parser) ParseArgs(doc string, argv []string, version string) (Opts, error) {
return p.parse(doc, argv, version)
}
// Deprecated: Parse is provided for backward compatibility with the original docopt.go package.
// Please rather make use of ParseDoc, ParseArgs, or use your own custom Parser.
func Parse(doc string, argv []string, help bool, version string, optionsFirst bool, exit ...bool) (map[string]interface{}, error) {
exitOk := true
if len(exit) > 0 {
exitOk = exit[0]
}
p := &Parser{
OptionsFirst: optionsFirst,
SkipHelpFlags: !help,
}
if exitOk {
p.HelpHandler = PrintHelpAndExit
} else {
p.HelpHandler = PrintHelpOnly
}
return p.parse(doc, argv, version)
}
func (p *Parser) parse(doc string, argv []string, version string) (map[string]interface{}, error) {
if argv == nil {
argv = os.Args[1:]
}
if p.HelpHandler == nil {
p.HelpHandler = DefaultParser.HelpHandler
}
args, output, err := parse(doc, argv, !p.SkipHelpFlags, version, p.OptionsFirst)
if _, ok := err.(*UserError); ok {
// the user gave us bad input
p.HelpHandler(err, output)
} else if len(output) > 0 && err == nil {
// the user asked for help or --version
p.HelpHandler(err, output)
}
return args, err
}
// -----------------------------------------------------------------------------
// parse and return a map of args, output and all errors
func parse(doc string, argv []string, help bool, version string, optionsFirst bool) (args map[string]interface{}, output string, err error) {
if argv == nil && len(os.Args) > 1 {
argv = os.Args[1:]
}
usageSections := parseSection("usage:", doc)
if len(usageSections) == 0 {
err = newLanguageError("\"usage:\" (case-insensitive) not found.")
return
}
if len(usageSections) > 1 {
err = newLanguageError("More than one \"usage:\" (case-insensitive).")
return
}
usage := usageSections[0]
options := parseDefaults(doc)
formal, err := formalUsage(usage)
if err != nil {
output = handleError(err, usage)
return
}
pat, err := parsePattern(formal, &options)
if err != nil {
output = handleError(err, usage)
return
}
patternArgv, err := parseArgv(newTokenList(argv, errorUser), &options, optionsFirst)
if err != nil {
output = handleError(err, usage)
return
}
patFlat, err := pat.flat(patternOption)
if err != nil {
output = handleError(err, usage)
return
}
patternOptions := patFlat.unique()
patFlat, err = pat.flat(patternOptionSSHORTCUT)
if err != nil {
output = handleError(err, usage)
return
}
for _, optionsShortcut := range patFlat {
docOptions := parseDefaults(doc)
optionsShortcut.children = docOptions.unique().diff(patternOptions)
}
if output = extras(help, version, patternArgv, doc); len(output) > 0 {
return
}
err = pat.fix()
if err != nil {
output = handleError(err, usage)
return
}
matched, left, collected := pat.match(&patternArgv, nil)
if matched && len(*left) == 0 {
patFlat, err = pat.flat(patternDefault)
if err != nil {
output = handleError(err, usage)
return
}
args = append(patFlat, *collected...).dictionary()
return
}
err = newUserError("")
output = handleError(err, usage)
return
}
func handleError(err error, usage string) string {
if _, ok := err.(*UserError); ok {
return strings.TrimSpace(fmt.Sprintf("%s\n%s", err, usage))
}
return ""
}
func parseSection(name, source string) []string {
p := regexp.MustCompile(`(?im)^([^\n]*` + name + `[^\n]*\n?(?:[ \t].*?(?:\n|$))*)`)
s := p.FindAllString(source, -1)
if s == nil {
s = []string{}
}
for i, v := range s {
s[i] = strings.TrimSpace(v)
}
return s
}
func parseDefaults(doc string) patternList {
defaults := patternList{}
p := regexp.MustCompile(`\n[ \t]*(-\S+?)`)
for _, s := range parseSection("options:", doc) {
// FIXME corner case "bla: options: --foo"
_, _, s = stringPartition(s, ":") // get rid of "options:"
split := p.Split("\n"+s, -1)[1:]
match := p.FindAllStringSubmatch("\n"+s, -1)
for i := range split {
optionDescription := match[i][1] + split[i]
if strings.HasPrefix(optionDescription, "-") {
defaults = append(defaults, parseOption(optionDescription))
}
}
}
return defaults
}
func parsePattern(source string, options *patternList) (*pattern, error) {
tokens := tokenListFromPattern(source)
result, err := parseExpr(tokens, options)
if err != nil {
return nil, err
}
if tokens.current() != nil {
return nil, tokens.errorFunc("unexpected ending: %s" + strings.Join(tokens.tokens, " "))
}
return newRequired(result...), nil
}
func parseArgv(tokens *tokenList, options *patternList, optionsFirst bool) (patternList, error) {
/*
Parse command-line argument vector.
If options_first:
argv ::= [ long | shorts ]* [ argument ]* [ '--' [ argument ]* ] ;
else:
argv ::= [ long | shorts | argument ]* [ '--' [ argument ]* ] ;
*/
parsed := patternList{}
for tokens.current() != nil {
if tokens.current().eq("--") {
for _, v := range tokens.tokens {
parsed = append(parsed, newArgument("", v))
}
return parsed, nil
} else if tokens.current().hasPrefix("--") {
pl, err := parseLong(tokens, options)
if err != nil {
return nil, err
}
parsed = append(parsed, pl...)
} else if tokens.current().hasPrefix("-") && !tokens.current().eq("-") {
ps, err := parseShorts(tokens, options)
if err != nil {
return nil, err
}
parsed = append(parsed, ps...)
} else if optionsFirst {
for _, v := range tokens.tokens {
parsed = append(parsed, newArgument("", v))
}
return parsed, nil
} else {
parsed = append(parsed, newArgument("", tokens.move().String()))
}
}
return parsed, nil
}
func parseOption(optionDescription string) *pattern {
optionDescription = strings.TrimSpace(optionDescription)
options, _, description := stringPartition(optionDescription, " ")
options = strings.Replace(options, ",", " ", -1)
options = strings.Replace(options, "=", " ", -1)
short := ""
long := ""
argcount := 0
var value interface{}
value = false
reDefault := regexp.MustCompile(`(?i)\[default: (.*)\]`)
for _, s := range strings.Fields(options) {
if strings.HasPrefix(s, "--") {
long = s
} else if strings.HasPrefix(s, "-") {
short = s
} else {
argcount = 1
}
if argcount > 0 {
matched := reDefault.FindAllStringSubmatch(description, -1)
if len(matched) > 0 {
value = matched[0][1]
} else {
value = nil
}
}
}
return newOption(short, long, argcount, value)
}
func parseExpr(tokens *tokenList, options *patternList) (patternList, error) {
// expr ::= seq ( '|' seq )* ;
seq, err := parseSeq(tokens, options)
if err != nil {
return nil, err
}
if !tokens.current().eq("|") {
return seq, nil
}
var result patternList
if len(seq) > 1 {
result = patternList{newRequired(seq...)}
} else {
result = seq
}
for tokens.current().eq("|") {
tokens.move()
seq, err = parseSeq(tokens, options)
if err != nil {
return nil, err
}
if len(seq) > 1 {
result = append(result, newRequired(seq...))
} else {
result = append(result, seq...)
}
}
if len(result) > 1 {
return patternList{newEither(result...)}, nil
}
return result, nil
}
func parseSeq(tokens *tokenList, options *patternList) (patternList, error) {
// seq ::= ( atom [ '...' ] )* ;
result := patternList{}
for !tokens.current().match(true, "]", ")", "|") {
atom, err := parseAtom(tokens, options)
if err != nil {
return nil, err
}
if tokens.current().eq("...") {
atom = patternList{newOneOrMore(atom...)}
tokens.move()
}
result = append(result, atom...)
}
return result, nil
}
func parseAtom(tokens *tokenList, options *patternList) (patternList, error) {
// atom ::= '(' expr ')' | '[' expr ']' | 'options' | long | shorts | argument | command ;
tok := tokens.current()
result := patternList{}
if tokens.current().match(false, "(", "[") {
tokens.move()
var matching string
pl, err := parseExpr(tokens, options)
if err != nil {
return nil, err
}
if tok.eq("(") {
matching = ")"
result = patternList{newRequired(pl...)}
} else if tok.eq("[") {
matching = "]"
result = patternList{newOptional(pl...)}
}
moved := tokens.move()
if !moved.eq(matching) {
return nil, tokens.errorFunc("unmatched '%s', expected: '%s' got: '%s'", tok, matching, moved)
}
return result, nil
} else if tok.eq("options") {
tokens.move()
return patternList{newOptionsShortcut()}, nil
} else if tok.hasPrefix("--") && !tok.eq("--") {
return parseLong(tokens, options)
} else if tok.hasPrefix("-") && !tok.eq("-") && !tok.eq("--") {
return parseShorts(tokens, options)
} else if tok.hasPrefix("<") && tok.hasSuffix(">") || tok.isUpper() {
return patternList{newArgument(tokens.move().String(), nil)}, nil
}
return patternList{newCommand(tokens.move().String(), false)}, nil
}
func parseLong(tokens *tokenList, options *patternList) (patternList, error) {
// long ::= '--' chars [ ( ' ' | '=' ) chars ] ;
long, eq, v := stringPartition(tokens.move().String(), "=")
var value interface{}
var opt *pattern
if eq == "" && v == "" {
value = nil
} else {
value = v
}
if !strings.HasPrefix(long, "--") {
return nil, newError("long option '%s' doesn't start with --", long)
}
similar := patternList{}
for _, o := range *options {
if o.long == long {
similar = append(similar, o)
}
}
if tokens.err == errorUser && len(similar) == 0 { // if no exact match
similar = patternList{}
for _, o := range *options {
if strings.HasPrefix(o.long, long) {
similar = append(similar, o)
}
}
}
if len(similar) > 1 { // might be simply specified ambiguously 2+ times?
similarLong := make([]string, len(similar))
for i, s := range similar {
similarLong[i] = s.long
}
return nil, tokens.errorFunc("%s is not a unique prefix: %s?", long, strings.Join(similarLong, ", "))
} else if len(similar) < 1 {
argcount := 0
if eq == "=" {
argcount = 1
}
opt = newOption("", long, argcount, false)
*options = append(*options, opt)
if tokens.err == errorUser {
var val interface{}
if argcount > 0 {
val = value
} else {
val = true
}
opt = newOption("", long, argcount, val)
}
} else {
opt = newOption(similar[0].short, similar[0].long, similar[0].argcount, similar[0].value)
if opt.argcount == 0 {
if value != nil {
return nil, tokens.errorFunc("%s must not have an argument", opt.long)
}
} else {
if value == nil {
if tokens.current().match(true, "--") {
return nil, tokens.errorFunc("%s requires argument", opt.long)
}
moved := tokens.move()
if moved != nil {
value = moved.String() // only set as string if not nil
}
}
}
if tokens.err == errorUser {
if value != nil {
opt.value = value
} else {
opt.value = true
}
}
}
return patternList{opt}, nil
}
func parseShorts(tokens *tokenList, options *patternList) (patternList, error) {
// shorts ::= '-' ( chars )* [ [ ' ' ] chars ] ;
tok := tokens.move()
if !tok.hasPrefix("-") || tok.hasPrefix("--") {
return nil, newError("short option '%s' doesn't start with -", tok)
}
left := strings.TrimLeft(tok.String(), "-")
parsed := patternList{}
for left != "" {
var opt *pattern
short := "-" + left[0:1]
left = left[1:]
similar := patternList{}
for _, o := range *options {
if o.short == short {
similar = append(similar, o)
}
}
if len(similar) > 1 {
return nil, tokens.errorFunc("%s is specified ambiguously %d times", short, len(similar))
} else if len(similar) < 1 {
opt = newOption(short, "", 0, false)
*options = append(*options, opt)
if tokens.err == errorUser {
opt = newOption(short, "", 0, true)
}
} else { // why copying is necessary here?
opt = newOption(short, similar[0].long, similar[0].argcount, similar[0].value)
var value interface{}
if opt.argcount > 0 {
if left == "" {
if tokens.current().match(true, "--") {
return nil, tokens.errorFunc("%s requires argument", short)
}
value = tokens.move().String()
} else {
value = left
left = ""
}
}
if tokens.err == errorUser {
if value != nil {
opt.value = value
} else {
opt.value = true
}
}
}
parsed = append(parsed, opt)
}
return parsed, nil
}
func formalUsage(section string) (string, error) {
_, _, section = stringPartition(section, ":") // drop "usage:"
pu := strings.Fields(section)
if len(pu) == 0 {
return "", newLanguageError("no fields found in usage (perhaps a spacing error).")
}
result := "( "
for _, s := range pu[1:] {
if s == pu[0] {
result += ") | ( "
} else {
result += s + " "
}
}
result += ")"
return result, nil
}
func extras(help bool, version string, options patternList, doc string) string {
if help {
for _, o := range options {
if (o.name == "-h" || o.name == "--help") && o.value == true {
return strings.Trim(doc, "\n")
}
}
}
if version != "" {
for _, o := range options {
if (o.name == "--version") && o.value == true {
return version
}
}
}
return ""
}
func stringPartition(s, sep string) (string, string, string) {
sepPos := strings.Index(s, sep)
if sepPos == -1 { // no seperator found
return s, "", ""
}
split := strings.SplitN(s, sep, 2)
return split[0], sep, split[1]
}
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