Class: Fabulator::Grammar::Expr::CharSet

Inherits:
Object
  • Object
show all
Defined in:
lib/fabulator/grammar/expr/char_set.rb

Direct Known Subclasses

CharClass

Instance Method Summary collapse

Constructor Details

#initialize(cs = "") ⇒ CharSet

Returns a new instance of CharSet.



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# File 'lib/fabulator/grammar/expr/char_set.rb', line 5

def initialize(cs = "")
  @set = BitSet.new
  if cs[0..0] == '-'
    @set.on(('-')[0])
    cs = cs[1..cs.length-1]
  end
  bits = cs.split(/-/) # to pull out ranges
  if bits.size == 1
    bits[0].each_char{ |c|
      @set.on(c[0])
    }
  elsif bits.size > 1
    if bits[0].size > 1
      @set.on(bits[0][0])
    end
    while(bits.size > 1)
      b = bits.shift
      if b.size > 2
        b[1..b.size-2].each_char { |c| @set.on(c[0]) }
      end
      @set.on(b[b.size-1] .. bits[0][0])
    end
    if bits[0].size > 1
      bits[0][1..bits[0].size-2].each_char { |c|
        @set.on(c[0])
      }
    end
  end
  self.compute_regex
end

Instance Method Details

#but_not(c) ⇒ Object 



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# File 'lib/fabulator/grammar/expr/char_set.rb', line 46

def but_not(c)
  @set = @set - c.set
  self.compute_regex
  self
end

#compute_regex ⇒ Object 



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# File 'lib/fabulator/grammar/expr/char_set.rb', line 62

def compute_regex
  # want a compact set of ranges for the regex
  set_def = ''
  @set.to_ary.each do |r|
    if r.is_a?(Range)
      set_def += Regexp.quote(r.begin.to_i.chr) + '-' + Regexp.quote(r.end.to_i.chr)
    else
      set_def += Regexp.quote(r.to_i.chr)
    end
  end
  if set_def == ''
    @regex = %r{.}
  else
    @regex = %r{[#{set_def}]}
  end
end

#or(c) ⇒ Object 



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# File 'lib/fabulator/grammar/expr/char_set.rb', line 40

def or(c)
  @set = @set | c.set
  self.compute_regex
  self
end

#set ⇒ Object 



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# File 'lib/fabulator/grammar/expr/char_set.rb', line 36

def set
  @set
end

#to_regex ⇒ Object 



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# File 'lib/fabulator/grammar/expr/char_set.rb', line 58

def to_regex
  @regex
end

#universal ⇒ Object

for now, we restrict ourselves to 8-bit characters



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# File 'lib/fabulator/grammar/expr/char_set.rb', line 53

def universal
  @set.on(0..0xff)
  self.compute_regex
end