slow_parsec.rb

class MatchError
  attr_accessor :r
  def initialize(a)
    @r = self
    @match = a
  end
  def >>(a)
    self
  end
  def >=(a)
    self
  end
  def |(a)
    p "match or"
    @match>>a
  end

  def m(a,b)
    self
  end
end

class End
  attr_accessor :r
  def initialize(a)
    @r = a
  end
  def >>(a)
    self
  end
  def >=(a)
    self
  end
  def |(a)
    self
  end

  def m(a,b)
    self
  end
  
end

class Match
  attr_accessor :s,:r
  def initialize(a)
    @init = a
    @s = a
  end
  def |(a)
    p "or"
    End.new(@r)
  end
  def >>(a)
    a.call(self)
  end
  def >=(a)
    @r=a.call(self)
    self
  end
  def m(a,b)
    s=~ a
    if $1 == nil then
      @s=@init
      return MatchError.new(self)
    end
    @s=$2
    singleton_class.class_eval { attr_accessor b }
    send("#{b}=", $1)
    self
  end
end
def int a
  ->s{s.m(/^([0-9]+)(.*$)/,a)}
end
def op a
  ->s{s.m(/^([+-])(.*$)/,a)}
end
def op2 a
  ->s{s.m(/^([*\/])(.*$)/,a)}
end
p ((((Match.new("123/456")>>int(:a)>>op(:o)>>int(:b)>=->s{[s.a,s.o,s.b]}) | int(:a))>>op2(:o)>>int(:b)>=->s{[s.a,s.o,s.b]}).r)
p (((Match.new("123-456")>>int(:a)>>op(:o)>>int(:b))>=->s{[s.a,s.o,s.b]}).r)
p (((Match.new("123-456")>>int(:a)>>op(:o)>>int(:b)>=->s{[s.a,s.o,s.b]}) | int(:a)).r)
p "--------"
p ((((Match.new("123-456")>>int(:a)>>op(:o)>>int(:b)>=->s{[s.a,s.o,s.b]}) | int(:a))>>op2(:o)).r)
p ((((Match.new("123-456")>>int(:a)>>op(:o)>>int(:b)>=->s{[s.a,s.o,s.b]}) | int(:a))>>op2(:o)>>int(:b)>=->s{[s.a,s.o,s.b]}).r)