Class: CodeRay::WordList

Inherits:
Hash
  • Object
show all
Defined in:
lib/coderay/helpers/word_list.rb

Overview

WordList

A Hash subclass designed for mapping word lists to token types.

Copyright © 2006 by murphy (Kornelius Kalnbach) <murphy rubychan de>

License

LGPL / ask the author

Version

1.1 (2006-Oct-19)

A WordList is a Hash with some additional features. It is intended to be used for keyword recognition.

WordList is highly optimized to be used in Scanners, typically to decide whether a given ident is a special token.

For case insensitive words use CaseIgnoringWordList.

Example:

# define word arrays
RESERVED_WORDS = %w[
  asm break case continue default do else
  ...
]

PREDEFINED_TYPES = %w[
  int long short char void
  ...
]

PREDEFINED_CONSTANTS = %w[
  EOF NULL ...
]

# make a WordList
IDENT_KIND = WordList.new(:ident).
  add(RESERVED_WORDS, :reserved).
  add(PREDEFINED_TYPES, :pre_type).
  add(PREDEFINED_CONSTANTS, :pre_constant)

...

def scan_tokens tokens, options
  ...

  elsif scan(/[A-Za-z_][A-Za-z_0-9]*/)
    # use it
    kind = IDENT_KIND[match]
    ...

Direct Known Subclasses

CaseIgnoringWordList

Instance Method Summary collapse

Constructor Details

#initialize(default = false, caching = false, &block) ⇒ WordList

Creates a new WordList with default as default value.

You can activate caching to store the results for every [] request.

With caching, methods like include? or delete may no longer behave as you expect. Therefore, it is recommended to use the [] method only.



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# File 'lib/coderay/helpers/word_list.rb', line 60

def initialize default = false, caching = false, &block
  if block
    raise ArgumentError, 'Can\'t combine block with caching.' if caching
    super(&block)
  else
    if caching
      super() do |h, k|
        h[k] = h.fetch k, default
      end
    else
      super default
    end
  end
end

Instance Method Details

#add(words, kind = true) ⇒ Object

Add words to the list and associate them with kind.

Returns self, so you can concat add calls.



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# File 'lib/coderay/helpers/word_list.rb', line 78

def add words, kind = true
  words.each do |word|
    self[word] = kind
  end
  self
end