(flex.info.gz) How can I expand macros in the input?

Info Catalog

(flex.info.gz) How can I change the matching pattern at run time?

(flex.info.gz) FAQ

(flex.info.gz) How can I build a two-pass scanner?

 
 How can I expand macros in the input?
 =====================================
 
 The best way to approach this problem is at a higher level, e.g., in
 the parser.
 
    However, you can do this using multiple input buffers.
 
 
      %%
      macro/[a-z]+	{
      /* Saw the macro "macro" followed by extra stuff. */
      main_buffer = YY_CURRENT_BUFFER;
      expansion_buffer = yy_scan_string(expand(yytext));
      yy_switch_to_buffer(expansion_buffer);
      }
 
      <<EOF>>	{
      if ( expansion_buffer )
      {
      // We were doing an expansion, return to where
      // we were.
      yy_switch_to_buffer(main_buffer);
      yy_delete_buffer(expansion_buffer);
      expansion_buffer = 0;
      }
      else
      yyterminate();
      }
 
    You probably will want a stack of expansion buffers to allow nested
 macros.  From the above though hopefully the idea is clear.
 

Info Catalog

(flex.info.gz) How can I change the matching pattern at run time?

(flex.info.gz) FAQ

(flex.info.gz) How can I build a two-pass scanner?