Class: ABNF::Alt

Inherits:
Elt
  • Object
show all
Defined in:
lib/abnf/abnf.rb,
lib/abnf/regexp.rb,
lib/abnf/regexp.rb,
lib/abnf/grammar.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Elt

#*, #+, #empty_sequence?, #remove_left_recursion, #remove_right_recursion, #rep, #|

Constructor Details

#initialize(*elts) ⇒ Alt

Returns a new instance of Alt.



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# File 'lib/abnf/grammar.rb', line 68

def initialize(*elts)
  @elts = elts
end

Instance Attribute Details

#elts ⇒ Object (readonly)

Returns the value of attribute elts.



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# File 'lib/abnf/grammar.rb', line 71

def elts
  @elts
end

Class Method Details

._new ⇒ Object 



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# File 'lib/abnf/grammar.rb', line 41

alias _new new

.new(*elts) ⇒ Object 



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# File 'lib/abnf/grammar.rb', line 44

def Alt.new(*elts)
  elts2 = []
  elts.each {|e|
	if e.empty_set?
	  next
    elsif Alt === e
	  elts2.concat e.elts
	elsif Term === e
	  if Term === elts2.last
 elts2[-1] = Term.new(elts2.last.natset + e.natset)
	  else
 elts2 << e
	  end
	else
	  elts2 << e
	end
  }
  case elts2.length
  when 0; EmptySet
  when 1; elts2.first
  else; Alt._new(*elts2)
  end
end

Instance Method Details

#each_var(&block) ⇒ Object 



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# File 'lib/abnf/grammar.rb', line 77

def each_var(&block) @elts.each {|elt| elt.each_var(&block)} end

#empty_set? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/abnf/grammar.rb', line 73

def empty_set?
  @elts.empty?
end

#recursion(syms, lhs) ⇒ Object 



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# File 'lib/abnf/regexp.rb', line 180

def recursion(syms, lhs)
  @elts.inject(0) {|r, e| r | e.recursion(syms, lhs)}
end

#regexp_tree ⇒ Object 



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# File 'lib/abnf/regexp.rb', line 390

def regexp_tree() RegexpTree.alt(*@elts.map {|e| e.regexp_tree}) end

#remove_just_recursion(n) ⇒ Object 



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# File 'lib/abnf/regexp.rb', line 184

def remove_just_recursion(n)
  Alt.new(*@elts.map {|e| e.remove_just_recursion(n)})
end

#split_left_recursion(n) ⇒ Object 



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# File 'lib/abnf/regexp.rb', line 188

def split_left_recursion(n)
  nonrec = EmptySet
  rest = EmptySet
  @elts.each {|e|
    nonrec1, rest1 = e.split_left_recursion(n)
	nonrec |= nonrec1
	rest |= rest1
  }
  [nonrec, rest]
end

#split_recursion(n) ⇒ Object 



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# File 'lib/abnf/regexp.rb', line 210

def split_recursion(n)
  rest_left = EmptySet
  nonrec = EmptySet
  rest_right = EmptySet
  @elts.each {|e|
    rest_left1, nonrec1, rest_right1 = e.split_recursion(n)
	rest_left |= rest_left1
	nonrec |= nonrec1
	rest_right |= rest_right1
  }
  [rest_left, nonrec, rest_right]
end

#split_right_recursion(n) ⇒ Object 



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# File 'lib/abnf/regexp.rb', line 199

def split_right_recursion(n)
  nonrec = EmptySet
  rest = EmptySet
  @elts.each {|e|
    nonrec1, rest1 = e.split_right_recursion(n)
	nonrec |= nonrec1
	rest |= rest1
  }
  [nonrec, rest]
end

#subst_var(&block) ⇒ Object 



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# File 'lib/abnf/grammar.rb', line 78

def subst_var(&block) Alt.new(*@elts.map {|elt| elt.subst_var(&block)}) end

#useful?(useful_names) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/abnf/abnf.rb', line 120

def useful?(useful_names) @elts.any? {|e| e.useful?(useful_names)} end