Genesis

1 files changed, 25 insertions, 0 deletions

diff --git a/include/__qmacros.h b/include/__qmacros.h
new file mode 100644
index 0000000..d765864
--- /dev/null
+++ b/include/__qmacros.h
@@ -0,0 +1,25 @@
+#ifndef MLIB___QMACROS_H
+#define MLIB___QMACROS_H
+
+/* Macros for qualifier-preserving functions.  These are wrappers around some
+   functions declared above which will return a const-qualified pointer if the
+   input string is const-qualified, and a non-const-qualified pointer otherwise.
+
+   The macros are taken from the N3020 proposal for C23. */
+
+/* clang-format off */
+#define _RUNE_PTR_IS_CONST(P) \
+	_Generic(1 ? (P) : (void *)(P), \
+	         const void *: 1, \
+	         default: 0)
+#define _RUNE_STATIC_IF(P, T, E) \
+	_Generic(&(char[!!(P) + 1]){0}, \
+	         char(*)[2]: T, \
+	         char(*)[1]: E)
+#define _RUNE_Q_PTR(T, F, S, ...) \
+	_RUNE_STATIC_IF(_RUNE_PTR_IS_CONST((S)), \
+	                (const T *)(F)(__VA_ARGS__), \
+	                      (T *)(F)(__VA_ARGS__))
+/* clang-format on */
+
+#endif /* !MLIB___QMACROS_H */