From: fdelente@...
Date: 2008-06-22T17:28:22+09:00
Subject: rex: howto use the lexer class?

Hello.

I'm trying to get rex to parse my inputs. After reading some of the sample
files provided with rex, I created this simple(?) file:

file: test.rex------------------------------------------------------------

# -*- ruby -*-
##########################################################################

class Lexer
  macro
    BLANKS \s+
    DIGITS \d+
    LETTERS [a-zA-Z]+
  rule
    {BLANKS}
    {LETTERS} { puts "ID: '@{text}'"; [ :ID, text ] }
    {DIGITS} { puts "NUMBER: '@{text}'"; [ :NUMBER, text.to_f ] }
    .|\n { puts "text: '@{text}'"; [ text, text ] }
  inner
end

##########################################################################
lexer=Lexer.new
while 1
  str=$stdin.gets.strip
  puts "str=@{str}"
  lexer.scan_str(str)
  puts "--------------------------------------------------------------------------"
end

end of file: test.rex-----------------------------------------------------

After 'rex test.rex', and 'ruby -Ku test.rex.rb', I always get errors like

test.rex.rb:60:in scan_evaluate': can not match: '2' (Lexer::ScanError)

when I type input.

Can anybody tell me why? Thanks.

-- 
Fabrice DELENTE