Dogcows Code - chaz/yoink/blob - src/moof/cml/core/cml_assert.h

   1 /* -*- C++ -*- ------------------------------------------------------------
   2
   3 Copyright (c) 2007 Jesse Anders and Demian Nave http://cmldev.net/
   4
   5 The Configurable Math Library (CML) is distributed under the terms of the
   6 Boost Software License, v1.0 (see cml/LICENSE for details).
   7
   8  *-----------------------------------------------------------------------*/
   9 /** @file
  10  *  @brief
  11  *
  12  * Macros and template metaprogramming to implement compile- and run-time
  13  * assertions.
  14  */
  15
  16 #ifndef cml_assert_h
  17 #define cml_assert_h
  18
  19 #include <cml/core/cml_meta.h>
  20
  21 namespace cml {
  22
  23 /* Join preprocessor macros into a new preprocessor macro: */
  24 #define CML_JOIN(X,Y) CML_DO_JOIN(X,Y)
  25 #define CML_DO_JOIN(X,Y) CML_DO_JOIN2(X,Y)
  26 #define CML_DO_JOIN2(X,Y) X##Y
  27
  28 /* Change a macro value into a string: */
  29 #define TO_STRING(X) TO_STRING2(X)
  30 #define TO_STRING2(X) #X
  31
  32 /** Default undefined compile-time assertion struct. */
  33 template<bool T> struct STATIC_ASSERTION_FAILURE;
  34
  35 /** Struct instantiated when a true assertion is made at compile-time. */
  36 template<> struct STATIC_ASSERTION_FAILURE<true> {
  37     typedef true_type result;
  38     enum { value = true };
  39 };
  40
  41 /** Create a compile-time assertion.
  42  *
  43  * @note Compile-time assertions must be expressions that can be evaluated at
  44  * comile time.  This means that the expression must only rely on constants,
  45  * enums, and/or template parameters, not variables having run-time storage
  46  * requirements.
  47  *
  48  * @warning Enclose expressions that have commas with parens, otherwise the
  49  * preprocessor will parse the commas as macro argument separators!
  50  *
  51  * @sa STATIC_ASSERTION_FAILURE
  52  */
  53 #define CML_STATIC_REQUIRE(_E_) \
  54     typedef typename STATIC_ASSERTION_FAILURE<(_E_)>::result \
  55         CML_JOIN(__cml_assert_test_typedef_, __LINE__)
  56
  57
  58 /** A more meaningful compile-time assertion struct.
  59  *
  60  * The parameter M is a struct type which has been declared but not
  61  * defined; e.g. struct this_is_an_error.
  62  *
  63  * When used with CML_STATIC_REQUIRE_M(<expr>,M), the compiler errors will
  64  * contain the struct name at the point of the error.
  65  */
  66 template<bool T, typename M> struct STATIC_ASSERTION_FAILURE_M {
  67     typename M::bogus result;
  68 };
  69
  70 /** Instantiated for true assertions. */
  71 template<typename M> struct STATIC_ASSERTION_FAILURE_M<true,M> {
  72     typedef true_type result;
  73     enum { value = true };
  74 };
  75
  76 /** Create a compile-time assertion with a message.
  77  *
  78  * @note Compile-time assertions must be expressions that can be evaluated at
  79  * comile time.  This means that the expression must only rely on constants,
  80  * enums, and/or template parameters, not variables having run-time storage
  81  * requirements.
  82  *
  83  * @warning Enclose expressions that have commas with parens, otherwise the
  84  * preprocessor will parse the commas as macro argument separators!
  85  *
  86  * @sa STATIC_ASSERTION_FAILURE_M
  87  */
  88 #define CML_STATIC_REQUIRE_M(_E_, _M_) \
  89     typedef typename STATIC_ASSERTION_FAILURE_M<(_E_),_M_> \
  90         ::result CML_JOIN(__bogus_assert_type_, __LINE__)
  91
  92 } // namespace cml
  93
  94 #endif
  95
  96 // -------------------------------------------------------------------------
  97 // vim:ft=cpp