external/bsd/flex/dist/examples/manual/pas_include.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 %x COMMENT
  18
  19
  20 %%
  21
  22 "{"                          BEGIN(COMMENT);
  23
  24 <COMMENT>"}"                 BEGIN(INITIAL);
  25 <COMMENT>"$include"[ \t]*"(" BEGIN(INCLUDE);
  26 <COMMENT>[ \t]*              /* skip whitespace */
  27
  28 <INCLUDE>")"                 BEGIN(COMMENT);
  29 <INCLUDE>[ \t]*              /* skip whitespace */
  30 <INCLUDE>[^ \t\n() ]+ {      /* get the include file name */
  31           if ( include_count >= MAX_NEST){
  32              fprintf( stderr, "Too many include files" );
  33              exit( 1 );
  34           }
  35
  36           include_stack[++include_count] = YY_CURRENT_BUFFER;
  37
  38           yyin = fopen( yytext, "r" );
  39           if ( ! yyin ){
  40              fprintf( stderr, "Unable to open %s",yytext);
  41              exit( 1 );
  42           }
  43
  44           yy_switch_to_buffer(yy_create_buffer(yyin,YY_BUF_SIZE));
  45
  46           BEGIN(INITIAL);
  47         }
  48 <INCLUDE><<EOF>>
  49         {
  50             fprintf( stderr, "EOF in include" );
  51             yyterminate();
  52         }
  53 <COMMENT><<EOF>>
  54         {
  55             fprintf( stderr, "EOF in comment" );
  56             yyterminate();
  57         }
  58 <<EOF>> {
  59           if ( include_count <= 0 ){
  60             yyterminate();
  61           } else {
  62             yy_delete_buffer(include_stack[include_count--] );
  63             yy_switch_to_buffer(include_stack[include_count] );
  64             BEGIN(INCLUDE);
  65           }
  66         }
  67 [a-z]+               ECHO;
  68 .|\n                 ECHO;
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