From: mailbox@dmitry-kazakov.de   
      
   On 29 Mar 2007 23:05:56 -0400, Ivan Boldyrev wrote:   
      
   > On 9791 day of my life msully wrote:   
   >> One of the exercises I am doing is writing a grammar for roman   
   >> numerals.   
   > ...   
   >> Comments?   
   >   
   > Now rewrite the grammar as a regular expression :)   
      
   Not in "regulars", but the following more or less obvious pattern   
      
   NOEMPTY   
   ( ['M'['M'['M']]]   
     ['C'['D'|'M'|'C'['C']] | 'D'['C'['C'['C']]]]   
     ['X'['L'|'C'|'X'['X']] | 'L'['X'['X'['X']]]]   
     ['I'['V'|'X'|'I'['I']] | 'V'['I'['I'['I']]]]   
   )   
      
   should do the trick. More complex were to use immediate assignments for   
   evaluation of the numeral's value it gets matched. But it is also doable.   
   Though a hand-written scanner would be faster and cleaner.   
      
   --   
   Regards,   
   Dmitry A. Kazakov   
   http://www.dmitry-kazakov.de   
      
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