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A simple OptionParser class to parse option flags from the command-line. Use it like so:

parser  = new OptionParser switches, helpBanner
options = parser.parse process.argv

The first non-option is considered to be the start of the file (and file option) list, and all subsequent arguments are left unparsed.

exports.OptionParser = class OptionParser

Initialize with a list of valid options, in the form:

[short-flag, long-flag, description]

Along with an an optional banner for the usage help.

  constructor: (rules, @banner) ->
    @rules = buildRules rules

Parse the list of arguments, populating an options object with all of the specified options, and return it. Options after the first non-option argument are treated as arguments. options.arguments will be an array containing the remaining arguments. This is a simpler API than many option parsers that allow you to attach callback actions for every flag. Instead, you're responsible for interpreting the options object.

  parse: (args) ->
    options = arguments: []
    skippingArgument = no
    originalArgs = args
    args = normalizeArguments args
    for arg, i in args
      if skippingArgument
        skippingArgument = no
      if arg is '--'
        pos = originalArgs.indexOf '--'
        options.arguments = options.arguments.concat originalArgs[(pos + 1)..]
      isOption = !!(arg.match(LONG_FLAG) or arg.match(SHORT_FLAG))

the CS option parser is a little odd; options after the first non-option argument are treated as non-option arguments themselves

      seenNonOptionArg = options.arguments.length > 0
      unless seenNonOptionArg
        matchedRule = no
        for rule in @rules
          if rule.shortFlag is arg or rule.longFlag is arg
            value = true
            if rule.hasArgument
              skippingArgument = yes
              value = args[i + 1]
            options[rule.name] = if rule.isList then (options[rule.name] or []).concat value else value
            matchedRule = yes
        throw new Error "unrecognized option: #{arg}" if isOption and not matchedRule
      if seenNonOptionArg or not isOption
        options.arguments.push arg

Return the help text for this OptionParser, listing and describing all of the valid options, for --help and such.

  help: ->
    lines = []
    lines.unshift "#{@banner}\n" if @banner
    for rule in @rules
      spaces  = 15 - rule.longFlag.length
      spaces  = if spaces > 0 then Array(spaces + 1).join(' ') else ''
      letPart = if rule.shortFlag then rule.shortFlag + ', ' else '    '
      lines.push '  ' + letPart + rule.longFlag + spaces + rule.description
    "\n#{ lines.join('\n') }\n"


Regex matchers for option flags.

LONG_FLAG  = /^(--\w[\w\-]*)/
SHORT_FLAG = /^(-\w)$/
MULTI_FLAG = /^-(\w{2,})/
OPTIONAL   = /\[(\w+(\*?))\]/

Build and return the list of option rules. If the optional short-flag is unspecified, leave it out by padding with null.

buildRules = (rules) ->
  for tuple in rules
    tuple.unshift null if tuple.length < 3
    buildRule tuple...

Build a rule from a -o short flag, a --output [DIR] long flag, and the description of what the option does.

buildRule = (shortFlag, longFlag, description, options = {}) ->
  match     = longFlag.match(OPTIONAL)
  longFlag  = longFlag.match(LONG_FLAG)[1]
    name:         longFlag.substr 2
    shortFlag:    shortFlag
    longFlag:     longFlag
    description:  description
    hasArgument:  !!(match and match[1])
    isList:       !!(match and match[2])

Normalize arguments by expanding merged flags into multiple flags. This allows you to have -wl be the same as --watch --lint.

normalizeArguments = (args) ->
  args = args[..]
  result = []
  for arg in args
    if match = arg.match MULTI_FLAG
      result.push '-' + l for l in match[1].split ''
      result.push arg