From: Jim Freeze <jim@...>
Date: 2003-12-12T05:23:05+09:00
Subject: Re: problems with racc: $end token

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On Friday, 12 December 2003 at  3:55:31 +0900, Luke A. Kanies wrote:

Hi Luke

I took your code and repeated the $end problem.
I removed the problem by putting an optional return
after your define { } block.

See code attached:


-- 
Jim Freeze
----------
Bubble Memory, n.:
	A derogatory term, usually referring to a person's
intelligence.  See also "vacuum tube".

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class CricketParser
 token DEFINE NAME STRING PARAM VALUE RETURN COMMENT WORD
 #INLINECOMMENT EOF
 
rule

start : objects
      ;
 
objects: object             { [val[0]] }
     | objects object       { [val[0], val[1]].flatten }
     ;
 
#object: DEFINE NAME '{' RETURN 
object: DEFINE WORD '{' RETURN 
          vars 
        '}' optreturns      {
                              Cricket.create(
                               val[1],val[3]) 
                            }
     ;
 
vars: var                   { [val[0]] }
     | vars var             { [val[0], val[1]].flatten }
     ;
 
#var: PARAM VALUE returns    { [val[0],val[1]] }
var: WORD WORD returns      { [val[0],val[1]] }
     ;
 
optreturns : /*none*/
           | returns
           ;

returns: return
     | returns return
     ;
 
return: comment RETURN
     ;
 
comment: # nothing
     | COMMENT
     ;
#     | INLINECOMMENT
 
end

---- inner
      
   
def parse(str)
  str.strip!
  str.gsub!(/[\r\f]/, "")
  @orig_lines = str.dup.split("\n")
  @line_no    = 1

  @q = []
  until str.empty? do
    case str

    #
    # Remove comments. Leaves \n
    #
    when /\A[ \t]*[#;].*$/
      str = $'

    #
    # Remove white space
    #
    when /\A[ \t]+/o
      #@q.push [:SPACE, " "]
      str = $'

    #
    # Tokenize new lines. Consolidate multiple NL into one.
    #
    when /\A\n+/o
      @line_no += $&.count("\n")
      unless @q.empty?
        @q.push [:RETURN, "\n"] unless 
          [:RETURN].include?(@q.last[0])
      end
      str = $'

    # keywords
    when /\A(define)\b/o
      id = $&.upcase.intern
      @q << [id, id]
      str = $'

    # WORD
    when /\A[a-zA-Z0-9_.@\-]+/o
      @q.push [:WORD, $&]
      str = $'

    # One character tokens
    else
      c = str[0,1]
      @q.push [c, c]
      str = str[1..-1]
    end#case

puts "@q:  #{@q.inspect}"

  end#until

puts "@q:  #{@q.inspect}" if $DEBUG
  do_parse
end

def next_token
  @q.shift
end


---- footer

if $0 == __FILE__ then
  file = <<-EOT
# a comment
define contact {
 contact_name                   vwf1607 ; inline comment
 alias                          Lawrence-Hubenak
 host_notification_period       none
 host_notification_commands     host-notify-by-email
 service_notification_period    none
 service_notification_commands  notify-by-email
 email                          lawrence.hubenak@hcahealthcare.com
 pager                          lawrence.hubenak@my2way.com
}

EOT

  class Cricket
    def initialize(a,b)
      @a,@b = a,b
    end
    def self.create(a,b)
      Cricket.new(a,b)
    end
  end#class Cricket

  puts 'parsing:'
  print file
  puts
  puts 'result:'
  p CricketParser.new.parse( file )
end



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