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module CodeRay

  # = Duo

  #

  # A Duo is a convenient way to use CodeRay. You just create a Duo,

  # giving it a lang (language of the input code) and a format (desired

  # output format), and call Duo#highlight with the code.

  # 

  # Duo makes it easy to re-use both scanner and encoder for a repetitive

  # task. It also provides a very easy interface syntax:

  # 

  #   require 'coderay'

  #   CodeRay::Duo[:python, :div].highlight 'import this'

  # 

  # Until you want to do uncommon things with CodeRay, I recommend to use

  # this method, since it takes care of everything.

  class Duo

    attr_accessor :lang, :format, :options

    # Create a new Duo, holding a lang and a format to highlight code.

    # 

    # simple:

    #   CodeRay::Duo[:ruby, :html].highlight 'bla 42'

    # 

    # with options:

    #   CodeRay::Duo[:ruby, :html, :hint => :debug].highlight '????::??'

    # 

    # alternative syntax without options:

    #   CodeRay::Duo[:ruby => :statistic].encode 'class << self; end'

    # 

    # alternative syntax with options:

    #   CodeRay::Duo[{ :ruby => :statistic }, :do => :something].encode 'abc'

    # 

    # The options are forwarded to scanner and encoder

    # (see CodeRay.get_scanner_options).

    def initialize lang = nil, format = nil, options = {}

      if format.nil? && lang.is_a?(Hash) && lang.size == 1

        @lang = lang.keys.first

        @format = lang[@lang]

      else

        @lang = lang

        @format = format

      end

      @options = options

    end

    class << self

      # To allow calls like Duo[:ruby, :html].highlight.

      alias [] new

    end

    # The scanner of the duo. Only created once.

    def scanner

      @scanner ||= CodeRay.scanner @lang, CodeRay.get_scanner_options(@options)

    end

    # The encoder of the duo. Only created once.

    def encoder

      @encoder ||= CodeRay.encoder @format, @options

    end

    # Tokenize and highlight the code using +scanner+ and +encoder+.

    def encode code, options = {}

      options = @options.merge options

      encoder.encode(code, @lang, options)

    end

    alias highlight encode

    # Allows to use Duo like a proc object:

    # 

    #  CodeRay::Duo[:python => :yaml].call(code)

    # 

    # or, in Ruby 1.9 and later:

    # 

    #  CodeRay::Duo[:python => :yaml].(code)

    alias call encode

  end

end