/*

 * eof_rules.lex : An example of using multiple buffers

 *                 EOF rules, and start states

 */

%{

#define MAX_NEST 10                   

YY_BUFFER_STATE include_stack[MAX_NEST];

int             include_count = -1;

%}

%x INCLUDE

%%

^"#include"[ \t]*\"  BEGIN(INCLUDE);

<INCLUDE>\"          BEGIN(INITIAL); 

<INCLUDE>[^\"]+ {      /* get the include file name */

          if ( include_count >= MAX_NEST){

             fprintf( stderr, "Too many include files" );

             exit( 1 );

          }

          include_stack[++include_count] = YY_CURRENT_BUFFER;

          yyin = fopen( yytext, "r" );

          if ( ! yyin ){

             fprintf( stderr, "Unable to open \"%s\"\n",yytext);

             exit( 1 );

          }

          yy_switch_to_buffer(yy_create_buffer(yyin,YY_BUF_SIZE));

          BEGIN(INITIAL);

        }

<INCLUDE><<EOF>> 

        {

            fprintf( stderr, "EOF in include" );

            yyterminate();

        }

<<EOF>> {

          if ( include_count <= 0 ){

            yyterminate();

          } else {

            yy_delete_buffer(include_stack[include_count--] );

            yy_switch_to_buffer(include_stack[include_count] );

            BEGIN(INCLUDE);

          }

        }

[a-z]+               ECHO;

.|\n                 ECHO;