Class: Calyx::Grammar::Production::Concat

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

Constant Summary collapse

EXPRESSION = 
/(\{[A-Za-z0-9_\.]+\})/.freeze
START_TOKEN = 
'{'.freeze
END_TOKEN = 
'}'.freeze
DEREF_TOKEN = 
'.'.freeze

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(expansion) ⇒ Concat

Returns a new instance of Concat.



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# File 'lib/calyx.rb', line 100

def initialize(expansion)
  @expansion = expansion
end

Class Method Details

.parse(production, registry) ⇒ Object 



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# File 'lib/calyx.rb', line 78

def self.parse(production, registry)
  expansion = production.split(EXPRESSION).map do |atom|
    if atom.is_a?(String)
      if atom.chars.first == START_TOKEN && atom.chars.last == END_TOKEN
        head, *tail = atom.slice(1, atom.length-2).split(DEREF_TOKEN)
        rule = NonTerminal.new(head, registry)
        unless tail.empty?
          Expression.new(rule, tail)
        else
          rule
        end
      else
        Terminal.new(atom)
      end
    elsif atom.is_a?(Symbol)
      NonTerminal.new(atom, registry)
    end
  end

  self.new(expansion)
end

Instance Method Details

#evaluate ⇒ Object 



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# File 'lib/calyx.rb', line 104

def evaluate
  @expansion.reduce('') do |exp, atom|
    exp << atom.evaluate
  end
end