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Lib/Include/CML/core/cml_assert.h

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+/* -*- C++ -*- ------------------------------------------------------------
+ 
+Copyright (c) 2007 Jesse Anders and Demian Nave http://cmldev.net/
+
+The Configurable Math Library (CML) is distributed under the terms of the
+Boost Software License, v1.0 (see cml/LICENSE for details).
+
+ *-----------------------------------------------------------------------*/
+/** @file
+ *  @brief
+ *
+ * Macros and template metaprogramming to implement compile- and run-time
+ * assertions.
+ */
+
+#ifndef cml_assert_h
+#define cml_assert_h
+
+#include <cml/core/cml_meta.h>
+
+namespace cml {
+
+/* Join preprocessor macros into a new preprocessor macro: */
+#define CML_JOIN(X,Y) CML_DO_JOIN(X,Y)
+#define CML_DO_JOIN(X,Y) CML_DO_JOIN2(X,Y)
+#define CML_DO_JOIN2(X,Y) X##Y
+
+/* Change a macro value into a string: */
+#define TO_STRING(X) TO_STRING2(X)
+#define TO_STRING2(X) #X
+
+/** Default undefined compile-time assertion struct. */
+template<bool T> struct STATIC_ASSERTION_FAILURE;
+
+/** Struct instantiated when a true assertion is made at compile-time. */
+template<> struct STATIC_ASSERTION_FAILURE<true> {
+    typedef true_type result;
+    enum { value = true };
+};
+
+/** Create a compile-time assertion.
+ *
+ * @note Compile-time assertions must be expressions that can be evaluated at
+ * comile time.  This means that the expression must only rely on constants,
+ * enums, and/or template parameters, not variables having run-time storage
+ * requirements.
+ *
+ * @warning Enclose expressions that have commas with parens, otherwise the
+ * preprocessor will parse the commas as macro argument separators!
+ *
+ * @sa STATIC_ASSERTION_FAILURE
+ */
+#define CML_STATIC_REQUIRE(_E_) \
+    typedef typename STATIC_ASSERTION_FAILURE<(_E_)>::result \
+        CML_JOIN(__cml_assert_test_typedef_, __LINE__)
+
+
+/** A more meaningful compile-time assertion struct.
+ *
+ * The parameter M is a struct type which has been declared but not
+ * defined; e.g. struct this_is_an_error.
+ *
+ * When used with CML_STATIC_REQUIRE_M(<expr>,M), the compiler errors will
+ * contain the struct name at the point of the error.
+ */
+template<bool T, typename M> struct STATIC_ASSERTION_FAILURE_M {
+    typename M::bogus result;
+};
+
+/** Instantiated for true assertions. */
+template<typename M> struct STATIC_ASSERTION_FAILURE_M<true,M> {
+    typedef true_type result;
+    enum { value = true };
+};
+
+/** Create a compile-time assertion with a message.
+ *
+ * @note Compile-time assertions must be expressions that can be evaluated at
+ * comile time.  This means that the expression must only rely on constants,
+ * enums, and/or template parameters, not variables having run-time storage
+ * requirements.
+ *
+ * @warning Enclose expressions that have commas with parens, otherwise the
+ * preprocessor will parse the commas as macro argument separators!
+ *
+ * @sa STATIC_ASSERTION_FAILURE_M
+ */
+#define CML_STATIC_REQUIRE_M(_E_, _M_) \
+    typedef typename STATIC_ASSERTION_FAILURE_M<(_E_),_M_> \
+        ::result CML_JOIN(__bogus_assert_type_, __LINE__)
+
+} // namespace cml
+
+#endif
+
+// -------------------------------------------------------------------------
+// vim:ft=cpp