www.pudn.com > LexYaccProgs.zip > MAGIC.L

 
%{ 
 
(* Lex demonstration program for the use of start states, taken from the UNIX 
   manual. This program copies standard input to standard output, and changes 
   the word `magic' to `first', `second' or `third' on any line that starts 
   with the letter a, b or c, respectively. 
 
   Try it out, e.g., by issuing the command `magic' and typing in the following 
   lines: 
 
     This is a magic word. 
     a This is a magic word. 
     b This is a magic word. 
     c This is a magic word. 
 
   The respond should be: 
 
     This is a magic word. 
     a This is a first word. 
     b This is a second word. 
     c This is a third word. 
 
   To compile this program: lex magic 
                            tpc magic 
 
*) 
 
uses LexLib; 
 
%} 
 
%S AA BB CC 
 
%% 
 
^a		begin 
		  echo; start(AA); 
		end; 
^b		begin 
		  echo; start(BB); 
		end; 
^c		begin 
		  echo; start(CC); 
		end; 
\n		begin 
		  echo; start(0); 
		end; 
magic	write('first'); 
magic	write('second'); 
magic	write('third'); 
.		echo; 
 
%% 
 
begin 
  if yylex=0 then ; 
end.