Class: Hammer::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/hammer/parser.rb

Overview

Parses ARGV into positional args and an options hash, given a set of ‘Option` definitions.

Instance Method Summary collapse

Constructor Details

#initialize(options) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/hammer/parser.rb', line 7

def initialize(options)
  @options    = options
  @by_switch  = {}
  options.each do |opt|
    register_switch(opt.switch, opt)
    register_switch(opt.negation, opt) if opt.boolean?
    opt.aliases.each { |a| register_switch(a, opt) }
  end
end

Instance Method Details

#parse(argv) ⇒ Object 



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# File 'lib/hammer/parser.rb', line 17

def parse(argv)
  positional = []
  values     = {}
  i = 0
  argv = argv.dup

  while i < argv.length
    token = argv[i]

    if token == '--'
      positional.concat(argv[(i + 1)..])
      break
    end

    if token.start_with?('--') && token.include?('=')
      key, val = token.split('=', 2)
      opt = lookup!(key)
      if opt.boolean? && key.start_with?('--no-')
        values[opt.name] = !opt.cast(val)   # `--no-x=false` -> true
      else
        values[opt.name] = opt.cast(val)
      end
      i += 1
      next
    end

    if @by_switch.key?(token)
      opt = @by_switch[token]
      if opt.boolean?
        values[opt.name] = !token.start_with?('--no-')
        i += 1
      else
        val = argv[i + 1]
        raise Error, "missing value for #{token}" if val.nil?
        values[opt.name] = opt.cast(val)
        i += 2
      end
      next
    end

    # Glued short flag with value: `-pVALUE` (non-boolean short opts only).
    if token.start_with?('-') && !token.start_with?('--') && token.length > 2
      if (opt = @by_switch[token[0, 2]]) && !opt.boolean?
        values[opt.name] = opt.cast(token[2..])
        i += 1
        next
      end
    end

    # Dash-led and not a negative number -> a genuinely unknown flag.
    # Bare `-` and negative numbers (`-5`) fall through to positionals.
    if token.start_with?('-') && token.length > 1 && token !~ /\A-\d/
      raise Error, "unknown option: #{token}"
    end

    positional << token
    i += 1
  end

  # Fill un-set non-boolean opts from positional args in declaration
  # order. Booleans always need an explicit flag. Scalars take one
  # positional each; an :array opt slurps whatever's left, so it's
  # filled last and never starves a later-declared scalar opt.
  array_opt = nil
  @options.each do |opt|
    next if opt.boolean? || values.key?(opt.name)
    if opt.type == :array
      array_opt = opt
      next
    end
    break if positional.empty?
    values[opt.name] = opt.cast(positional.shift)
  end
  if array_opt && !positional.empty?
    values[array_opt.name] = array_opt.cast(positional.shift(positional.size))
  end

  @options.each do |opt|
    values[opt.name] = opt.default if !values.key?(opt.name) && !opt.default.nil?
    raise Error, "missing required --#{opt.name}" if opt.required && !values.key?(opt.name)
  end

  [positional, values]
end