src/lib/cc/tokpaste.h

   1 /* Copyright (c) 2001 Matej Pfajfar.
   2  * Copyright (c) 2001-2004, Roger Dingledine.
   3  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   4  * Copyright (c) 2007-2021, The Tor Project, Inc. */
   5 /* See LICENSE for licensing information */
   6
   7 /**
   8  * @file tokpaste.h
   9  * @brief Token-pasting macros.
  10  **/
  11
  12 #ifndef TOR_LIB_CC_TOKPASTE_H
  13 #define TOR_LIB_CC_TOKPASTE_H
  14
  15 /**
  16  * Concatenate `a` and `b` in a way that allows their result itself to be
  17  * expanded by the preprocessor.
  18  *
  19  * Ordinarily you could just say `a ## b` in a macro definition.  But doing so
  20  * results in a symbol which the preprocessor will not then expand.  If you
  21  * wanted to use `a ## b` to create the name of a macro and have the
  22  * preprocessor expand _that_ macro, you need to have another level of
  23  * indirection, as this macro provides.
  24  **/
  25 #define PASTE(a,b) PASTE__(a,b)
  26
  27 /** Helper for PASTE(). */
  28 #define PASTE__(a,b) a ## b
  29
  30 #endif /* !defined(TOR_LIB_CC_TOKPASTE_H) */