SoundSoftware Code Site

module CodeRay

  # = WordList

  # 

  # <b>A Hash subclass designed for mapping word lists to token types.</b>

  # 

  # Copyright (c) 2006-2011 by murphy (Kornelius Kalnbach) <murphy rubychan de>

  #

  # License:: LGPL / ask the author

  # Version:: 2.0 (2011-05-08)

  #

  # A WordList is a Hash with some additional features.

  # It is intended to be used for keyword recognition.

  #

  # WordList is optimized to be used in Scanners,

  # typically to decide whether a given ident is a special token.

  #

  # For case insensitive words use WordList::CaseIgnoring.

  #

  # Example:

  #

  #  # define word arrays

  #  RESERVED_WORDS = %w[

  #    asm break case continue default do else

  #  ]

  #  

  #  PREDEFINED_TYPES = %w[

  #    int long short char void

  #  ]

  #  

  #  # make a WordList

  #  IDENT_KIND = WordList.new(:ident).

  #    add(RESERVED_WORDS, :reserved).

  #    add(PREDEFINED_TYPES, :predefined_type)

  #  

  #  ...

  #  

  #  def scan_tokens tokens, options

  #    ...

  #    

  #    elsif scan(/[A-Za-z_][A-Za-z_0-9]*/)

  #      # use it

  #      kind = IDENT_KIND[match]

  #      ...

  class WordList < Hash

    # Create a new WordList with +default+ as default value.

    def initialize default = false

      super default

    end

    # Add words to the list and associate them with +value+.

    # 

    # Returns +self+, so you can concat add calls.

    def add words, value = true

      words.each { |word| self[word] = value }

      self

    end

  end

  # A CaseIgnoring WordList is like a WordList, only that

  # keys are compared case-insensitively (normalizing keys using +downcase+).

  class WordList::CaseIgnoring < WordList

    def [] key

      super key.downcase

    end

    def []= key, value

      super key.downcase, value

    end

  end

end