external/bsd/flex/dist/examples/manual/eof_rules.lex

   1 /*
   2  * eof_rules.lex : An example of using multiple buffers
   3  *                 EOF rules, and start states
   4  */
   5
   6 %{
   7
   8 #define MAX_NEST 10
   9
  10 YY_BUFFER_STATE include_stack[MAX_NEST];
  11 int             include_count = -1;
  12
  13 %}
  14
  15
  16 %x INCLUDE
  17
  18 %%
  19
  20 ^"#include"[ \t]*\"  BEGIN(INCLUDE);
  21 <INCLUDE>\"          BEGIN(INITIAL);
  22 <INCLUDE>[^\"]+ {      /* get the include file name */
  23           if ( include_count >= MAX_NEST){
  24              fprintf( stderr, "Too many include files" );
  25              exit( 1 );
  26           }
  27
  28           include_stack[++include_count] = YY_CURRENT_BUFFER;
  29
  30           yyin = fopen( yytext, "r" );
  31           if ( ! yyin ){
  32              fprintf( stderr, "Unable to open \"%s\"\n",yytext);
  33              exit( 1 );
  34           }
  35
  36           yy_switch_to_buffer(yy_create_buffer(yyin,YY_BUF_SIZE));
  37
  38           BEGIN(INITIAL);
  39         }
  40 <INCLUDE><<EOF>>
  41         {
  42             fprintf( stderr, "EOF in include" );
  43             yyterminate();
  44         }
  45 <<EOF>> {
  46           if ( include_count <= 0 ){
  47             yyterminate();
  48           } else {
  49             yy_delete_buffer(include_stack[include_count--] );
  50             yy_switch_to_buffer(include_stack[include_count] );
  51             BEGIN(INCLUDE);
  52           }
  53         }
  54 [a-z]+               ECHO;
  55 .|\n                 ECHO;
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