stdlib/optparse/version.rb

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# frozen_string_literal: false
# OptionParser internal utility

class << OptionParser
  def show_version(*pkgs)
    progname = ARGV.options.program_name
    result = false
    show = proc do |klass, cname, version|
      str = progname.to_s
      unless (klass == ::Object) && (cname == :VERSION)
        version = version.join('.') if Array === version
        str << ": #{klass}" unless klass == Object
        str << " version #{version}"
      end
      %i[Release RELEASE].find do |rel|
        if klass.const_defined?(rel)
          str << " (#{klass.const_get(rel)})"
        end
      end
      puts str
      result = true
    end
    if (pkgs.size == 1) && (pkgs[0] == 'all')
      search_const(::Object, /\AV(?:ERSION|ersion)\z/) do |klass, cname, version|
        unless (cname[1] == 'e') && klass.const_defined?(:Version)
          show.call(klass, cname.intern, version)
        end
      end
    else
      pkgs.each do |pkg|
        pkg = pkg.split(/::|\//).inject(::Object) { |m, c| m.const_get(c) }
        v = case
            when pkg.const_defined?(:Version)
              pkg.const_get(n = :Version)
            when pkg.const_defined?(:VERSION)
              pkg.const_get(n = :VERSION)
            else
              n = nil
              'unknown'
            end
        show.call(pkg, n, v)
      rescue NameError
      end
    end
    result
  end

  def each_const(path, base = ::Object)
    path.split(/::|\//).inject(base) do |klass, name|
      raise NameError, path unless Module === klass
      klass.constants.grep(/#{name}/i) do |c|
        klass.const_defined?(c) || next
        klass.const_get(c)
      end
    end
  end

  def search_const(klass, name)
    klasses = [klass]
    while klass = klasses.shift
      klass.constants.each do |cname|
        klass.const_defined?(cname) || next
        const = klass.const_get(cname)
        yield klass, cname, const if name === cname
        klasses << const if (Module === const) && (const != ::Object)
      end
    end
  end
end