shell.l

/*
 *
 * CS-413 Spring 98
 * shell.l: lexical analyzer for shell
 * You have to extend it.
 *
 */

%{

#include <string.h>
#include "y.tab.h"

%}

%%

\n 	{
		return NEWLINE;
	}

[ \t] 	{
		/* Discard spaces and tabs */
     	}	
     	
\|	{
		return PIPE;
	}
	
"&>>"	{
		return ERR;
	}
	
&	{
		return AMPERSAND;
	}

">>" 	{
		return DOUBLEGREAT;
	}

">" 	{
		return GREAT;
	}
	
"<" 	{
		return LESS;
	}
	
"exit"	{
		return EXIT;
	}
	
"cd"	{
		return CD;
	}

[^ \t\n\|&<>][^ \t\n\|&<>]*  {
		/* Assume that file names have only alpha chars */
		yylval.string_val = strdup(yytext);
		return WORD;
	}

%%